Saturday, March 30, 2013

Mar 30, 2013: Winter Approaching Its End

Forecast Highlights:

After a prolonged period of colder than average temperatures with winter-like conditions continuing beyond the official end of winter, the cold pattern is approaching its end. Temperatures have warmed up well into the 50s today with similar temperatures for Sunday and Monday, but the sustained warmth is not here to stay yet with a final period of cold temperatures next week.

Thursday, March 28, 2013

Mar 28, 2013 Brief Update

Reminder: The next full update will be posted on Saturday, March 30.

Friday - Weekend: Warmer, Some Rain

After a consistent chilly pattern through mid-late March, temperatures have finally warmed enough to pass 50 degrees, although still remaining slightly cooler than average. Mostly sunny skies are expected for Friday and Saturday, with highs on Friday in the low to mid 50s and on Saturday in the mid 50s across most of the area, reaching the upper 50s near NYC. Based on latest indications, temperatures are expected to remain below 60 degrees, making this the first March since 2001 to fail to reach 60 degrees. A cold front is then expected to move through on Sunday, with highs mostly in the low 50s along with occasional periods of rain, mostly in the afternoon and evening hours.

Next Week: Colder Pattern To Return

As another cold front moves through the region, much warmer temperatures are briefly expected on Monday, reaching the upper 50s to mid 60s across the area. This surge of warmth is only short lasting, however, as a strong trough returns for the rest of the week with temperatures again colder than average. A wave of low pressure is expected to move through the region on Monday night into Tuesday morning, producing showers and the possibility for some snow, depending on how much precipitation is left over when temperatures reach freezing. Temperatures through the rest of the week are expected to remain in the 40s to low 50s for highs, with overnight lows in the 20s inland and low to mid 30s for the rest of the area. A gradual warm up is expected towards next weekend with temperatures potentially reaching average again.

Tuesday, March 26, 2013

Mar 26, 2013 Brief Update

Reminder: Due to a very busy schedule, the blog will remain on a limited posting schedule this week. Full daily updates are likely to be resumed on Saturday, March 30. For the remainder of this week, brief forecast updates will be posted on Tuesday and Thursday.

This Week - Weekend: Gradually Warming Up

Partly cloudy skies are expected to persist through Friday, with temperatures gradually warming up, reaching the 50s for the first time since earlier this month. Highs will generally end up in the upper 40s to low 50s, with isolated showers possible especially on Thursday. Overnight lows will also warm up, reaching the upper 20s to low 30s inland and the low to mid 30s across the rest of the area.

By next weekend, a brief warm up is expected with mostly sunny skies as temperatures rise into the low to mid 50s across the area for highs, perhaps reaching the upper 50s on Sunday. Should temperatures fail to reach 60 degrees, this will be the first March to have failed to reach this mark in NYC since 2001.

Longer Range: No Break From Blocking Pattern Yet

The weather pattern appears to pull its own April Fools joke, as despite a brief warm up at the end of March with the most spring-like conditions since early in the month, a trough is expected to return for the beginning of April with another cold air mass likely to drop into the region, continuing the current winter-like pattern that has been in place for the last 2 weeks. The latest models are likely overdoing the intensity of the cold air, but the overall theme is for continued colder than average temperatures, with highs likely in the 40s and possibly 50s. While it is uncertain if this pattern results in any additional widespread snow in the region or simply cold and dry conditions, any persistent spring-like pattern still remains on hold.

Monday, March 25, 2013

Mar 24, 2013: Some Snow Tomorrow

Forecast Highlights:

A late season snowstorm will affect the region tomorrow, continuing the colder and snowier than average pattern that has been in place for the last 10 days. Some snow is expected from this storm in the area, with most of the snow staying to the south. Afterwards, a colder than average pattern will persist through the rest of the month and into April with hardly any precipitation for the following week.

Friday, March 22, 2013

Mar 22, 2013 Brief Update

Note: The blog will be on a limited posting schedule through Monday with occasional brief updates. The next full update will be posted on Tuesday night.

- Weekend Outlook: Mostly to partly sunny skies are expected to continue through the weekend, with highs on Saturday peaking in the low to mid 40s across most of the area, and on Sunday in the mid to upper 40s.

- Monday Storm Update: The latest model guidance remains split on Monday's storm, between the storm scraping the area with rain/snow showers and a more significant snowstorm across the area, especially west of NYC. At this time, at least a light-moderate impact event is likely with widespread rain/snow, especially south of the area, with precipitation type potentially leaning more towards snow west of NYC, although the forecast is still subject to some changes over the next few days.

- Longer Range: Beyond the Monday storm, temperatures are expected to generally remain colder than average, in the 40s for highs and 20s/30s for lows, through at least the last few days of the month.

Thursday, March 21, 2013

Mar 21, 2013: Pattern Likely To Continue Into April

Forecast Highlights:

A coastal low developed well offshore today with scattered snow showers observed and temperatures generally peaking in the 30s across the area, continuing the colder than average in place since the 14th. With the current pattern expected to last through at least early April, temperatures will remain mostly colder than average for the rest of the month, and additional snow events are still likely to affect the region and possibly the area.

Mar 20, 2013: Some Snow Tonight, Next Week's Storm

Forecast Highlights:

Temperatures were once again cooler than average across the area as an abnormally strong blocking pattern continued, with temperatures expected to remain generally colder than average for the remainder of the month into early April. Additional snow is still expected this winter, including scattered snow squalls tonight and another storm potential for Monday.

Tuesday, March 19, 2013

Mar 19, 2013: Winter Pattern Continues Into Spring

This is the second part of tonight's post, which is separated into two parts. The first part is an overview of the March 18 snowstorm, and the second part is a forecast update.

Forecast Highlights:

A snowstorm affected the area yesterday with more snow than expected, adding onto what is already a cold and snowy March compared to recent years. Temperatures today were warmer than those of yesterday, but still remained colder than average. Winter is still not over, however; a highly anomalous blocking pattern remains in place, with temperatures remaining mostly colder than average for the rest of the month, continuing past the first official day of spring, with the potential for more snow events in the region.

Mar 18, 2013 Storm Summary

This is the first part of tonight's post, which is separated into two parts. The first part is an overview of the March 18 snowstorm, and the second part is a forecast update.

Brief Storm Summary:

A late season snowstorm affected the area on March 18-19, the latest snow event with widespread accumulating snow for the area since March 24, 2011. Widespread accumulations were reported across the area, generally ranging from 1 to 4 inches in most of Long Island and NYC, 2 to 5 inches in the north/west suburbs of NYC, 3 to 6 inches in southern CT, and 4 to 7 inches towards NW NJ and southeastern NY.

Monday, March 18, 2013

Mar 18-19, 2013 Storm Updates

Occasional updates will be posted below on the late season rain, snow and ice event currently affecting the region. Yesterday's forecast discussion for this storm can be found here.

Latest Twitter Updates:  (Scroll to the bottom of the post for blog updates)

Blog Updates:

12:40 AM: Since the last update, the sleet/rain line gradually moved north, with NYC, then parts of Long Island and northern NJ changing over to sleet and then rain. The end of the precipitation shield is moving much faster than expected as noted earlier, especially with no precipitation over parts of Pennsylvania where the models originally had moderate-heavy rain that would have resulted in steady moderate rain overnight for the area. While the radar is filling in over New Jersey, it's not doing so to the extent that was originally modeled, and steady precipitation is expected to continue through at least 2-4 AM before becoming lighter, mixing with sleet and freezing rain inland where ice may be a concern for the morning commute. Temperatures will continue to warm on Tuesday afternoon into the low to mid 40s for most of the area with showers ending.

While the timing of the changeover to sleet and rain was generally close to the forecast, a little slower than expected for some locations, the snow that fell was heavier than expected, and while it was expected to be more of a wet snowfall that would struggle to accumulate,  the snow began to accumulate not long after falling and continued to steadily add up unlike typical late March snow events which are typically marginal for snow accumulations, more like a January than a late March snow event. Snow rates of near to locally over 1 inch per hour were observed, which exceeded the forecast. Based on preliminary storm reports from the National Weather Service, snow totals as of 12 AM were anywhere from 1/2 to 5 inches in southern CT, up to 2 inches in Long Island and 3" in Nassau county, 1-4 inches in NYC, 2-5 inches in the north/west suburbs, and 3-6 inches for NW NJ and SE NY.

9:50 PM: Snow, heavy at times, continues to fall across most of the area, although southern areas near NYC are seeing mixing with sleet and some rain. Totals are already reaching 3-5 inches across parts of northern NJ, with just under 2 inches reported in Central Park. Over the next few hours, the mixing line will continue to shift north, with the immediate NYC area changing to rain and interior areas to freezing rain and rain, with precipitation gradually becoming lighter. Snow totals of 1-4 inches are expected in NYC and western LI, 2-5 inches for the north/west suburbs, and 4-7 inches for the interior parts of the area.

8:30 PM: Over the last hour, heavy snow fell over the immediate NYC area, with snow rates of over 1 inch per hour reported in some locations. With these rates of accumulations, the snow is already exceeding the forecast across most of the area. The latest revised snow forecast is for 1-3 inches in NYC, 2-4 inches for the north/west suburbs, and 3-6 inches for interior parts of the area. The snow is expected to gradually mix with and change over to sleet and rain over the next few hours as temperatures begin to gradually climb, but with less rain than initially expected for the overnight hours.

7:15 PM: Currently, widespread moderate snow is falling from NYC and further west, mixing with sleet near NYC and parts of NE NJ. Meanwhile, steadier precipitation is starting to spread into Long Island and Connecticut. Accumulations reported so far are generally under an inch, with another 2-4 hours of moderate snow expected over northern NJ before precipitation gradually continues to change over to sleet and then rain. A development in the forecast is for an earlier than expected ending; based on latest trends, the steady precipitation may end before the early morning hours, with only showers persisting through Tuesday afternoon.

4:30 PM: Throughout the early-mid afternoon hours, snow began developing over western Pennsylvania, gradually spreading east and NE into the rest of the state. As of 4:30 PM, light snow/sleet has started to spread into western parts of the area. The arrival of precipitation so far is slightly slower than expected, while another trend to note is that western Pennsylvania is not seeing any precipitation currently, while most of the 12z models had heavy precipitation falling there at this time. This trend will continue to be monitored tonight in case the forecast snow and precipitation amounts need to be lowered.

The expectation at this time is for snow to continue to spread in and intensify, with moderate snow west of NYC late this evening. Towards 9 PM, NYC and Long Island are expected to change over to rain, with the rain/snow line gradually moving north, reaching the rest of northern NJ towards 11 PM, while NW NJ, interior SE NY and southern CT away from the coast change over to a mix of snow, sleet and freezing rain, later on changing to plain rain towards 2 AM. Forecast snow totals are for little to no accumulations in NYC and Long Island, up to an inch for the immediate N/W suburbs, 1-3 inches for the interior suburbs and 2-5 inches for interior parts of the area.

Sunday, March 17, 2013

Mar 17, 2013: Rain, Snow, Ice Tomorrow Night

Forecast Highlights:

The colder than average pattern continues across the region with no sign of falling apart anytime soon, as the area observed another day with highs in the 30s to low 40s. A storm is expected to affect the region on Monday into early Tuesday, producing snow, ice and rain across the area with accumulations expected north and west of NYC, followed by continued cold temperatures for the rest of the week.

Click here for latest 5-day forecast >>

Saturday, March 16, 2013

Mar 16, 2013: More Snow, Rain For Monday Night

Forecast Highlights:

A late season light snow event affected the area today, with minimal accumulations under 1 inch observed for some locations. Since then, snow has ended across the area, with chilly temperatures expected to continue on Sunday. This is not the last snow event of the winter yet, however, as another storm affects the region on Monday and Tuesday, producing heavy rain as well as accumulating snow across the interior regions and parts of the area.

Mar 16, 2013 Storm Updates

Brief updates will be posted below on the light snow event currently affecting the region. Yesterday's forecast discussion for this and the following storms can be found here.

Latest Twitter Updates:  (Scroll to the bottom of the post for blog updates)

Blog Updates:

2:30 PM: Over the last 2 hours, widespread moderate snow spread into northern NJ and NYC, with light snow falling elsewhere. Temperatures have slightly cooled down due to the precipitation, remaining unseasonably chilly for a mid March afternoon with temperatures in the mid 30s in northern NJ/SE NY and upper 30s further east. The snow is sticking to mostly non-paved surfaces in northern NJ under the moderate band.

Snow is expected to continue falling through this evening, with accumulations in northern NJ from a coating to 2 inches mostly on non-paved surfaces. Other parts of the area are expected to see light snow with minimal accumulations. Chilly temperatures are expected again for Sunday, but the break between storms won't last long until the next storm affects the area on Monday with more accumulating snow expected as the winter-like pattern continues.

12:15 PM: As of 12 PM, the area is mainly cloudy with isolated rain/snow showers for some locations. A narrow band of moderate to heavy snow is located over the I-80 corridor over central Pennsylvania, spreading east/ESE. This precipitation is expected to begin drying up as it reaches the area, but still looks to be capable of supporting a narrow band of moderate snow reaching the area starting at about 2 PM and through the evening hours. The focus of this narrow band of moderate snow looks to be around the I-80 and I-76 corridors in northern NJ, possibly into New York City and parts of western Long Island, with light snow showers elsewhere. Under this band, a coating to 2 inches of snow can be expected, with the highest totals further west in New Jersey, with no accumulations expected in NYC. Other parts of the area will see scattered snow showers, mixing with rain for eastern areas, with little to no accumulations. Due to the cloud cover and precipitation, temperatures will remain chilly today, only peaking in the upper 30s to low 40s across most of the area.

Below is a snow map for today's snow. This map mostly focuses on the placement of the moderate snow band with less emphasis on the exact specifics of the snow placement and accumulations; there will likely be some accumulations outside of the darker blue zone, with snow flurries also falling outside of the highlighted light blue area as well.

Friday, March 15, 2013

Mar 15, 2013: Cold, Stormy Pattern; Snowy For Some

Forecast Highlights:

Starting on Wednesday night, a strong trough moved into the region, marking the beginning of a winter-like pattern in spring, with temperatures generally near to below average persisting through the end of the month and potentially into April. With the pattern in place, additional storminess is expected, including Tuesday and potentially next weekend, and the region will see more snowstorms before the winter ends, potentially in the NYC area as well.

Thursday, March 14, 2013

Mar 13, 2013: Colder Pattern Begins

Forecast Highlights:

Today was the last day of the temporary warm up with highs again in the 40s to low 50s across the area. Following scattered showers this evening, drier conditions will return for Thursday and Friday as a strong trough moves through the region, with temperatures moderately colder than average on both days. With the current pattern in place, no warm pattern is in sight for a while, with several storms expected to affect the region during this time period as well, one of them next Tuesday.

Tuesday, March 12, 2013

Mar 12, 2013: Colder Pattern To Develop, Persist

Forecast Highlights:

After today's heavy rain event, one more day of seasonably mild conditions is left, with highs reaching the upper 40s to mid 50s tomorrow. Winter is not over yet, however; a blocking pattern is expected to develop, with temperatures starting on Thursday staying near to below average across the region for the majority of the foreseeable range. Along with the cold pattern comes the potential for additional snow in the Northeast US and potentially in the NYC area.

Monday, March 11, 2013

Mar 11, 2013: Rain Tomorrow, Then Colder

Forecast Highlights:

Another day of mild temperatures with highs in the 50s for parts of the area was observed, with similar temperatures expected to continue through Wednesday. A cold front will move through the region on Tuesday, producing heavy rain, followed by colder than average temperatures returning for the mid to late week, peaking on Thursday but persisting through the weekend and into the following week.

Sunday, March 10, 2013

Mar 10, 2013: Winter Not Over Yet

Forecast Highlights:

An onshore flow developed today, keeping temperatures cooler near coastal areas in the 40s while interior locations warmed up into the 50s. Similar conditions are expected for Monday ahead of the next storm on Tuesday, with a cold front expected to result in windy conditions for parts of the area and heavy rainfall up to or locally over an inch. This cold front will mark the end of the current spring-like temperatures as a colder pattern returns and persists for a while, putting any warm pattern on hold.

Click here for latest 5-day forecast >>

Mar 9, 2013: Mild Weekend, Then Colder

This post is the second part of tonight's update, which was separated into two parts. The first part is a review of the mid-late week storm, and the second part is a forecast update.

Forecast Highlights:

After the surprise significant snowstorm on Friday, the system that has affected the region since Tuesday left just in time for a mostly sunny and mild weekend, with highs reaching the mid to upper 50s across most of the area. Similar conditions will continue through the early week before a cold front produces rain, possibly heavy, on Tuesday, followed by a colder pattern expected to develop, likely to put a persistent spring-like pattern on hold for a while.

Mar 9, 2013: Mid-Late Week Storm Overview

This post is the first part of tonight's update, which was separated into two parts. The first part is a review of the mid-late week storm, and the second part to be posted shortly is a forecast update.

Mid-Late Week Storm Brief Review

Over the mid-late week period, the area was affected by a long duration storm, with two rounds of precipitation. The first was associated with a coastal low on Wednesday night, while the second was with an inverted trough on Thursday night into Friday. Forecasting these two rounds of precipitation proved to be difficult with variable performance of the model guidance, resulting in less snow than expected with the first storm and more snow than expected with the second storm.

Wednesday, March 6, 2013

Mar 6-8, 2013 Storm Updates

Below, updates will be posted on the rain, snow and wind event affecting the region from Wednesday through Friday. The blog will remain in storm update mode through this time period; the next forecast discussion will be posted on Saturday.

Storm updates will be resumed by 6 PM tonight.

Latest Twitter Updates:  (Scroll to the bottom of the post for blog updates)

Blog Updates:

Friday, March 8

1:15 PM: Snow continued to fall throughout the last few hours, although temperatures are slightly warming up, already above freezing in parts of the area which could result in some more difficulty for the snow to accumulate compared to last night and this morning. The snow bands continue to hold steady over Massachusetts and interior Connecticut, where the storm significantly exceeded all expectations with 20-24 inches of snow possible in some locations, although snow is starting to weaken further west over NYC and NJ. Snow will continue falling through the mid afternoon hours, gradually mixing with light rain in some areas as it ends, with additional light accumulations expected mainly over NE NJ, Connecticut and parts of Long Island.

The next forecast discussion will be posted on Saturday, along with an overview of this storm and what went wrong with both forecasts, for the coastal low when less snow than expected fell, and the inverted trough when much more snow than expected fell.

10:50 AM: Steady light to moderate snow continues to fall across the area, locally heavy over northeastern NJ and parts of Connecticut. As of 10 AM, more widespread totals of over 10 inches have been reported across southern CT and SE NY according to the National Weather Service. With at least a few more hours of snow left, which for southern and western parts of the area may mix with rain as the storm ends, additional accumulations are expected, with totals in northern parts of the area locally as high as 12-16 inches. Totals remain lower in parts of New Jersey, NYC and Long Island, with totals near 1-3 inches generally reported in Manhattan, the lowest across the area.

8:25 AM: As of this morning, snow continues to fall across most of the region. The snow remains generally moderate, locally heavy in some spots and especially towards New England. Unlike the coastal low, when less snow than expected fell, snow totals so far exceeded the forecast, in some cases significantly so, across many parts of the region. The highest total so far is 13 inches in Hortontown, NY (Putnam), with totals of 10" in Armonk, NY (Westchester), Harriman, NY (Orange), and Danbury, CT. Totals locally as high as 6-9 inches have also been reported in Long Island and northern NJ. Not all of the area overperformed, however, with parts of Long Island and NYC still at 1-4 inches so far.

Many models showed a general 2-5 inch snowfall across the region with totals locally over 5 inches north of the area; the NAM was the most bullish, suggesting widespread 12-18 inches across northern New Jersey into eastern NY state. While the NAM's totals are still overdone even compared to the current observations, it was correct with heavier banding over New England into the area with more snow than what most of the models indicated. In this case, however, the NAM's scenario originally appeared to be more of an outlier than usual, especially considering that just 24 hours ago it had a major bust with the coastal storm, showing 1/2 to 1 inch of precipitation near and west of NYC where hardly anything fell.

Snow will continue to fall through the early afternoon hours, gradually mixing with rain and ending by the early-mid afternoon. Additional light to locally moderate accumulations are expected through then, although snow rates could decrease by the end of the storm especially as temperatures slightly increase. Clearing skies and lighter winds are expected tonight giving way to sunny and mild conditions for the weekend as temperatures climb to nearly 50 degrees, which should result in a quick melting of today's snowfall. Total accumulations are likely to end up between 6 and 14 inches across southern CT and SE NY, 3 to 9 inches in northern NJ and Long Island, and 2 to 6 inches in NYC. Totals may be locally lower in some areas and locally higher in other areas.

12:45 AM: Moderate to locally heavy snow continues to fall across most of Connecticut, northern NJ, with heavier snow bands expected to spread into southeastern New York soon. Totals in some locations have already reached the forecast range, with snow expected to continue through the early-mid morning hours. Under these locations in southern CT, SE NY and parts of NE NJ, totals are increasingly likely to reach and locally exceed 6-8 inches. Elsewhere across the area, light to moderate snow continues to fall, with accumulations of at least 2 to 4 inches expected for most.

Thursday, March 7

11:20 PM: Through the evening and early night hours, steady light to moderate snow continued to fall across most of the area, mixing with rain at times in some locations, with the heaviest snow bands so far over the Hartford to New Haven, CT corridor, extending into parts of Long Island.Accumulations have been reported in SE NY, southern CT, and parts of Long Island and northern NJ, with totals locally as high as 3-5 inches already reported in parts of SE NY.

The moderate to heavy snow bands remain over Connecticut and western Long Island, slowly shifting west towards the Hudson Valley into the immediate NYC area. Additional snow is expected to fall through the overnight into the morning hours, with snow gradually mixing with rain and then ending by the late morning to early afternoon hours. Totals are still expected to end up between 3-6 inches in SE NY, southern CT and parts of Long Island, with 2-4 inches elsewhere, locally lower near NYC and western NJ. Given the current snow accumulations, the potential is there for totals to end up locally higher than 6 inches in SE NY and southern CT.

7:15 PM: Steady rain and snow showers have continued to fall throughout the day, and steadily intensified this evening as an inverted trough continues to take shape across the region. Precipitation type earlier was generally rain or non-accumulating snow, although with the time of the day and cooling temperatures, precipitation type is changing over to more widespread snow which is starting to accumulate in parts of northern NJ, SE NY and southern CT.

Light to moderate snow, locally heavy, is generally expected to continue focusing over southern New England, the Hudson Valley, and parts of the area through Friday in the late morning hours. The heaviest snow totals are expected into southern CT and eastern parts of SE NY, with 3 to 6 inches of snow; totals locally above 6 inches are possible in Connecticut. Long Island is expected to see 2 to 5 inches of snow, with 2 to 4 inches for the rest of the area, with amounts below 2 inches in some spots such as NYC and western NJ.

11:30 AM: Since last night's update, the low pressure continued to gradually drift to the east, although precipitation continues to expand northwest into New England and the area. From NYC and further north and west, the forecast last night for the coastal busted on the high side with precipitation failing to spread as far north as expected, with little to no accumulations observed. Some snow is currently falling in these areas, but is struggling to accumulate due to warm surface temperatures and snow rates not heavy enough. East of NYC into most of southern Connecticut, light to moderate snow still fell; amounts busted on the high side as well compared to the original forecast, instead ending up closer to the revised forecast last night for up to 2 inches, locally higher, as totals above 1 inch have been reported across parts of Long Island with amounts locally near/slightly over 2 inches further east where heavier snow fell last night. Rain/snow showers continue to fall in Long Island and CT as of this morning.

Forecast Update: Scattered rain/snow showers are expected to continue today with minimal accumulations considering the warmer surface temperatures and lack of heavy precipitation rates. The next round of the storm is expected tonight as an inverted trough sets up, producing more snow across the region, but north of the coastal low. The focus of tonight's snow is expected north of the area, into New England and eastern NY state, with moderate snow expected over southern CT and possibly Long Island. The main uncertainty at this time is how far west the snow spreads. Last night's update mentioned one bust potential would be if precipitation stays too far north/east for the area to receive widespread moderate accumulations. Some of this morning's models are showing this scenario, keeping accumulations over 3 inches north and east of NYC, with lower totals for NYC, northern NJ and southeastern NY.

The current forecast for tonight is 1 to 3 inches of snow in NYC and northern NJ, with similar totals in Long Island but locally higher, 2 to 4 inches in southeast NY, and 3 to 6 inches in southern CT. These totals are still subject to minor revisions, and more information will be posted throughout the day.

Wednesday, March 6

11:00 PM: As of 10 PM, there is a broad low pressure south of Long Island and east of southeastern VA. The minimum pressure is approximately 994mb, and the system is generally drifting east.

Since this afternoon's update, precipitation has still failed to spread north into most of northern New Jersey, and aside from an earlier period of light snow mixed with some rain, it appears most locations north and west of NYC will fail to see more than scattered light precipitation tonight with less than 1 inch of snow. Last night's update mentioned that only a small difference with the northern end of the heavier precipitation would have a larger impact on the area, and so far this is setting up south of the expectation even from earlier today, resulting in the forecast busting on the high side with snow totals across the area tonight. Locations east of NYC are currently observing rain/snow and are expected to continue seeing light to moderate precipitation through the early-mid overnight hours, with snow accumulations generally up to 1-2 inches. From NYC and north/west, little to no accumulations are expected tonight.

Tonight's bust is unlikely to repeat in a similar style tomorrow night, however. After scattered precipitation through the day on Thursday, generally in the form of light rain/snow, an inverted trough is expected to develop as an upper level low drops southeast through the region, later on phasing with the coastal low once both systems are well offshore. While tonight's forecast had a larger bust potential, there is high confidence on widespread snow on Thursday night with additional accumulations expected. The main uncertainty at this time is exactly how much snow accumulates. The NAM is still being disregarded as an extreme wet outlier, and overall thinking at this time is for 2 to 4 inches of snow along/south of the I-80 corridor into NYC and Long Island, locally lower, with 3 to 5 inches of snow generally north of I-80 into southern Connecticut. Totals especially towards parts of the Hudson Valley and the Catskills may be locally above 5 inches. Some changes are still possible to this forecast, with more information to be posted with the next update on Thursday morning. One possible outcome which would result in less snow is if snow from the inverted trough focuses too far north for widespread moderate snow accumulations in the area, and this possibility will be monitored.

4:10 PM: As of 3 PM, there is a broad area of low pressure located south of NYC and east of southeastern VA. The minimum pressure is approximately 993mb, and the low is generally drifting east.

Since the update earlier today, surface temperatures across the Mid Atlantic have warmed up enough that only portions of central Virginia remain with plain snow, while other areas are generally seeing rain or mixing with some snow/sleet. Strong winds are occurring across coastal areas, with widespread gusts above 40 mph across New Jersey and Long Island. Gusts up to or locally over 60 mph have been reported along the immediate coastal areas in New Jersey.

Update - this map is no longer valid. Refer to the update above for more information.

Precipitation from the coastal low is struggling to expand north, is already verifying south of what the NAM had - the 12z NAM, which showed approximately 0.50" of liquid equivalent precipitation from the coastal low tonight in NYC, already had widespread light to moderate precipitation covering all of NYC and northern NJ by 4 PM with 0.10" of precipitation accumulated by NYC, which as can be seen on the radar posted above, is missing. The NAM is still adjusting south with the precipitation from the coastal low tonight, as its earlier runs significantly exaggerated the precipitation totals in the area. At this time, a general 1-4 inches of snow are expected tonight in the immediate NYC area into Long Island and southern CT, with the high end of this range towards Long Island and southeastern CT. Scattered rain/snow showers are then expected on Thursday.

Thursday Night Update: The main snow event is still expected to take place on Thursday night into Friday morning with an inverted trough. As the coastal low continues to drift more to the east, widespread light to moderate snow is expected to develop over New York state and northern New England towards Thursday evening. Throughout the overnight hours, this band of moderate snow will continue to expand west into east central NY state, then drop south through the area, with moderate snow expected on Friday morning for most of the area especially from the immediate NYC area and further north, including western CT. As the mid levels begin to warm along with surface temperatures, a changeover to sleet/rain is possible from NE to SW on Friday morning precipitation weakens and shifts south of the area, marking the end of the storm by early Friday afternoon with clearing skies and lighter winds just in time for the weekend.

There is some uncertainty regarding exact accumulations, with most models suggesting a light to moderate event while the NAM is the most bullish. Given the NAM's wet bias and performance with today's storm, I am disregarding the NAM as a wet outlier, although snow is expected to fall across the area considering precipitation associated with the inverted trough is expected to be widespread. At this time, I am generally expecting a 2-5 inch event, with the heaviest totals locally over 5 inches likely to end up north of NYC into the Hudson Valley region. These amounts are still subject to minor changes, however. More information on this will be posted with later updates.

12:00 PM: As of 11 AM, the low pressure was located south of New Jersey and east of the southern tip of the Delmarva Peninsula. The minimum pressure is approximately 992mb, and the low is intensifying while tracking to the ENE.

Throughout late last night and this morning, moderate to heavy precipitation spread into the Mid Atlantic region. Initially, this fell as widespread snow, although temperatures warmed up this morning with many locations outside of western Virginia and Maryland changing over to a mix or rain. Later into the early-mid afternoon hours, precipitation is expected to start spreading into the area as well. This will generally be light rain or a rain/snow mix, which will gradually change over to snow towards the evening hours as surface temperatures cool down.

Coastal Low Update: Last night's forecast discussion noted there was still uncertainty regarding how far north the heavy precipitation from the coastal low extends, with minor differences resulting in more significant changes to the forecast. The more bullish models as of last night, the NAM and SREF, have gradually backed to the south, but remain wetter than most other models with near to slightly over 0.50" liquid equivalent precipitation near NYC. Taking the mild surface temperatures and generally moderate snow rates into consideration, such precipitation amounts will not translate to 5 inches of snow as they typically would under normal 10:1 liquid to snow ratios, but generally lighter amounts.

Northwestern parts of the area are expected to be in the edge of the coastal low, and are generally expected to see 2 inches or less. Towards the immediate NYC area and western Long Island/SW CT, a period of moderate snow is likely tonight followed by the snow becoming lighter after about 2 AM. Amounts are generally likely to end up between 1 and 3 inches, locally up to 4 inches. The highest amounts are expected towards central-eastern Long Island and SE CT, where 2 to 5 inches are expected.

Thursday Night Update: After scattered rain/snow showers on Thursday, the second and more significant part of the storm is expected for Thursday night, as an inverted trough takes shape over New York state, later dropping south into the area, producing additional moderate precipitation. Initially, this is expected to be snow across most of the area, but as mid level warming takes place, starting in New England and expanding southwest, snow will gradually mix with and change over to sleet/rain from northeast to southwest towards Friday morning. The storm is finally expected to end on Friday afternoon, with clearing skies towards the evening hours.

How much snow falls and accumulates partially depends on the mid level warming, as the NAM is currently the most bullish with this while the GFS and RGEM keep temperatures cold enough for plain snow. At this time, I sided with a mostly snow approach but with mixed precipitation late overnight into Friday morning, with additional snowfall of 2 to 4 inches likely across most of the area, especially from NYC and further north/west and into western CT. This part of the forecast is still subject to minor revisions.

Mar 5, 2013: Rain, Snow, Wind For Weds-Friday

Forecast Highlights:

More sunshine was observed across the region today with lighter winds and warmer temperatures, peaking in the mid 40s to low 50s across the area. Cloud cover already began to increase across the region with precipitation spreading into the Mid Atlantic, however, as the most significant storm to affect the region since the early February blizzard continues to approach, with a long duration rain, snow, wind and coastal flooding event lasting through Friday.

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Tuesday, March 5, 2013

Mar 5, 2013 Noon Update

12:00 PM: Models Trending Weaker With Storm

The forecast for the mid-late week storm continues to become complicated with several new trends on today's models. Last night's update noted that the GFS was significantly north with the storm while the rest of the models were south. With the other model runs last night and this morning, the rest of the models failed to add support to the GFS; instead, the GFS trended south, especially with its 12z run, no longer supporting a major precipitation event for the NYC area, although the Mid Atlantic and New England still receive moderate to heavy snow.

Model trends have been inconsistent this year, and this sudden change in the GFS needs to be approached  with caution, as with yesterday's GFS runs which were significantly north of the rest of the models, and from what current indications suggest were likely too far north. Yesterday's forecast sided with a compromise of the GFS/ECM, which would have resulted in at least 1/2 to 1 inch of liquid equivalent precipitation across the area with over 1 inch towards parts of Long Island. For the afternoon update, I am lowering forecast precipitation totals, which shows the potential for light snow accumulations from NYC and north/west, with strong winds still expected. I will continue to monitor today's trends, and additional changes will be posted with this evening's update. Precipitation amounts may be lowered further with the next update, and the original solution of light rain/snow showers remains a valid possibility, although the possibility is there for an inverted trough on Thursday night to increase precipitation totals for at least parts of the area.

Regardless of the track, however, strong winds and coastal flooding are still expected for the coast. A strong NE to NNE wind of 20-30 mph across the area, up to 35 mph in Long Island, with gusts generally up to/over 40 mph, perhaps up to 45-50 mph in Long Island. Minor to moderate coastal flooding is also likely for coastal areas, with a storm surge up to 2-4 feet possible. More information on this will be posted tonight.

Mar 4, 2013: Significant Nor'easter Likely Wed-Thu

Forecast Highlights:

Temperatures remained slightly below average today as the same pattern continued of breezy NW winds and partial cloud cover. Temperatures tomorrow will be slightly warmer with winds shifting NE ahead of the next storm, which will produce widespread impacts in the region with rain, wet snow, wind and coastal flooding.

Monday, March 4, 2013

Mar 4, 2013 Noon Update

3:30 PM: Weds-Thurs Storm Update

The last few days have brought yet another round of model inconsistencies with the upcoming storm. Initially, the models suggested a major nor'easter, but then backed down completely to a storm staying well south of the area. At that time, the possibility remained for a further north storm with more impact in the area, which currently appears to be the trend.

The GFS remains the northernmost model and has continued to trend even more north than its previous runs, now showing a major storm affecting the region with heavy rain, snow and wind for the NYC area. The SREFs also support the GFS along with the GFS ensemble members, otherwise the rest of the models remain south, if not well south, with the ECMWF still closer to the southern end of today's models with less precipitation in the area. More information will be posted with this evening's update, but despite a lack of general support for a significant storm aside from the aforementioned models, I am currently leaning closer to the idea of a significant storm than a storm mostly missing the area to the south.

The 5-day forecast has been revised earlier today; high probability of precipitation remains from yesterday's update, with probabilities increased for interior areas, with heavier precipitation now expected. The forecast will be discussed in more details tonight although the storm is expected to be mainly rain for the coast, a heavy rain/snow mix for the immediate NYC area, and a moderate to significant wet snowstorm inland. Strong winds are expected as well with widespread gusts up to 40 mph, perhaps up to 50 mph east and south of NYC, with coastal flooding a concern for coastal areas. Stay tuned for more information tonight.

Sunday, March 3, 2013

Mar 3, 2013: Nor'easter Expected, Impact Uncertain

Forecast Highlights:

After yesterday's unexpected light snow event at night, less cloud cover was observed today with highs peaking in the upper 30s to low 40s across the area. Slightly warmer temperatures are expected for Monday and Tuesday ahead of the next storm, expected to affect the region from Wednesday through Thursday night and possibly Friday. Significant impacts are likely from this storm in the Mid Atlantic region, although there is uncertainty with the exact storm impact in the NYC area.

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Mar 2, 2013: Slightly Chilly Pattern Continues

Forecast Highlights:

A strong trough remains in place over the region, keeping temperatures slightly below average across the region, peaking in the upper 30s to low 40s across the area, while a surprise band of snow in the evening produced. Similar conditions are expected to continue through the middle of next week, when a storm will affect parts of the region, possibly including the area, with rain and snow.

Saturday, March 2, 2013

Mar 2, 2013 Evening Update

8:10 PM: Light Snow Affecting Area

An area of moderate snow is currently affecting the immediate NYC area, focusing on NE NJ, SE NY and NYC, and is slowly drifting to the east. Snow showers in this band are capable of resulting in a coating of snow with locally higher amounts up to 1 inch possible, with the snow showers gradually winding down over the next few hours.

The next forecast update will be posted later tonight.

Friday, March 1, 2013

Mar 1, 2013: Chilly Pattern; Storm Possible Next Week

Forecast Highlights:

Following the mid week storm, drier but partly to mostly cloudy conditions took place over the last two days, and are expected to continue through this weekend into early next week as temperatures slightly cool down. The next potential for a storm is expected towards the middle of next week, with the latest models still not having reached an agreement but pointing towards a potentially significant storm for parts of the region.