Jan 7, 2012 Morning: 60 Degrees Today

12 PM: Very Warm Today


The model guidance has once again underestimated the warmth for today, as temperatures have already surged into the lower to mid 50s across a large part of the area, the same temperatures that the models showed as the daytime highs for today. With a warm southwest wind and sunshine, unusually warm temperatures for January are expected today, surging into the mid to upper 50s inland and the upper 50s to lower 60s across the rest of the area. Temperatures may reach 65 degrees near NYC today. These temperatures are 20 degrees warmer than average. Colder temperatures will return for tomorrow although still staying 5-10 degrees warmer than average, reaching the mid 40s for highs across most of the area.


The 5-Day Forecast page has been updated for the area from NYC and further west. A full update for the day will be posted this afternoon, covering the heavy rain for late this week and what may follow afterwards.

Updated Winter 2011-2012 Outlook

Note: Minor revisions have been made to this outlook on January 7.

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As of the time that this was posted, on January 6th, New York City still has not seen snow since October, making this year a likely candidate for the latest first measurable snowfall in the December-February time frame in recorded history. By this time of the year in 2010-2011, the area has already seen a major blizzard, and a cold and snowy pattern was just beginning to unfold. This year, however, the majority of the winter so far has sen warmer than average temperatures, in some cases much warmer than average, and there is still no snow event in sight for the next 7-10 days at least. There are changes unfolding in the pattern, and NYC will see snow this winter, a few inches at the very least, although t he winter will most likely end up with below average snow.


Pattern Change Development


The focus of my winter outlook created in late November and published in early December was the potential for a pattern change towards the middle of January, with a mild pattern through early January with below average snow across the region. The outlook also mentioned that although a colder and snowier pattern could develop afterwards, the best risk of snowstorms would still stay to the north of the area, with some snow events for the area but also including more frequent mixing with sleet and rain. Through early January, the pattern so far has generally followed the expectation, with a warmer than average East and only a few snowstorms across the entire Northeast region, even up to the Great Lakes and northern New England region which typically see much more snow by this time of the year.

The pattern has been very stubborn over the northern hemisphere, with a consistently cold stratosphere, near record cold at times, with a sustained polar vortex near the Greenland and Alaska regions preventing the development of Greenland blocking and a -NAO, needed for Mid Atlantic cold and snow, and an absence of ridging near the west coast and Alaska, needed to provide amplification in the pattern which results in a better chance of cold and snow in the East. There has not been much amplification with this pattern as it remains very progressive, with cold spells staying flat and quickly moving out. The most amplification the East has seen so far this winter was with the cold spell on January 3-5, which also was able to quickly move out and weaken with yet another surge of warmth spreading east. There have been minor changes with the pattern in the US, as the ridge in the southeastern US that resulted in the very mild temperatures throughout November and most of December has significantly weakened. Temperatures are still mostly warmer than average, although significant warm spells with temperatures surging to 55-65 degrees are nowhere near as frequent as they have been earlier in the winter. The large scale pattern, however, has not changed yet, so the eastern half of the US is still seeing few significant snow events with generally above average temperatures.

A change is starting to unfold, however. A round of sudden stratospheric warming began to take place not too long ago, although for now the warming is mostly confined to the 1-10 hPa regions. The reaction from the stratospheric warming to changing the pattern to a cold and snowy one is not instant, especially if the stratospheric warming backs off slightly, which is a possibility. At the same time, the pattern that is in place is still firmly in place, with many indications supporting this, ranging from the MJO struggling to move into the phases favorable for eastern US cold/snow, the lack of ridging near Greenland due to the stubborn polar vortex, and the frequent polar vortex over Alaska as well helping to keep the EPO positive. As the original winter outlook showed, a positive EPO tends to result in above average temperatures, especially for the northern US including the northern Mid Atlantic. Considering that the pattern is still generally locked into place with only occasional minor changes, it will take time for any pattern change to unfold, and it is appearing more likely at this time that while improvements may very well take place with the pattern, the current pattern may never completely fall apart, with signs of a Greenland and Alaskan polar vortex still returning along with difficulty to establish -NAO and blocking. Despite this, however, the changes that are unfolding will help to make the pattern a colder and snowier one, especially with ridging developing near Alaska and more stratospheric warming, along with the potential for slightly negative NAO/AO at times towards the longer range, which will help to bring more cold into the northern US along with more snowstorms for the Great Lakes into the Northeast and the NYC area occasionally.

Another factor to consider is the historical analogs. As I have stated in some of my recent daily discussions, there have only been two Decembers without snow in Central Park in recorded history; 2006 and 1877. Both of these winters ended up with well below average snowfall, with the total winter snowfall ending up near 12.4 inches in 2006-07 and 8.1 inches in 1877-78. The fact that only two other winters had no snow in December in addition to this year shows just how unusual this pattern is; furthermore, both of these winters did not have snow events prior to December, while this year there was an October snowstorm. The fact that there was a significant snowstorm in October but no snow in December in NYC is yet another evidence that so far, this winter is unusual. In addition, in the three other winters in recorded history when snow accumulated in October in NYC, accumulating snow fell in both November and December as well. Only two winters with no snow in December is a small list of analog winters, but even when looking through the 15 winters that had a trace of snow in December, all of them except for one had below average snowfall, with more than half of them ending up with less than 20 inches of snow for the entire winter. While history does not always have to repeat itself, these historical references strongly suggest that probability of reaching average snow this winter is low.


Outlook for January - March

With the factors mentioned above, for now I am thinking that the pattern begins to change in the second half of January, especially towards the end of the month, but with the pattern still locked into place, it is very possible that the pattern as it is now, although changing towards more cold and snow, fails to completely fall apart, with the result ending up as a "gradient" pattern, where the Northeast and Great Lakes are favored for snow events while the northern Mid Atlantic sees some mixed precipitation events but more frequently rain and/or a wintry mix instead of snow. These changes in the pattern will also bring some snow events to the NYC area and the northern Mid Atlantic, especially between the end of January into March, although snowstorms are more likely to stay on the moderate side, with a lower probability of any significant snow event like those of the last two winters. Possible variables of this pattern include a neutral/negative EPO, neutral/negative PNA, and a neutral to slightly positive NAO/AO, dropping to negative at times but at least as of now, not likely to stay negative the majority of the time from late January through February. The changes in the pattern are likely to stick around through February and possibly into March for parts of the region, and although the area will see some snow events, this winter is most likely on track to end up warmer than average with below average snowfall, potentially well below average in the scenario that no significant winter storm affects the northern Mid Atlantic or closer to average if the pattern change is stronger than currently expected.

For the second half of January, gradual changes in the pattern are likely, with the first snow of the meteorological winter expected sometime around this time frame for NYC, along with temperatures potentially ending up near average, possibly slightly below average should more cold be able to drop south from Canada; the near-slightly below average temperature forecast assumes that there will be some changes, although in the case that the NAO/AO remain solidly positive, slightly above average temperatures would continue. With the changes sticking through February and March, temperatures for both months may end up once again averaging near to slightly above average for the NYC area, although more cold and snow is likely for the Great Lakes and Northeast regions, with occasional periods of cold and snow also affecting the NYC area in February and March.


Summary:

Considering that this is still in the longer range, there are still uncertainties in the forecast. It is possible that the pattern stays similar to where it is now through the rest of the winter, the result being very little snow for the entire winter in the Mid Atlantic region, including NYC, with only a few snow events from now through the rest of the winter. Such scenarios, although definitely uncommon, have happened with some of the winters where the patterns were also mild with little snow. In the other scenario, more significant changes with the pattern would take place, and while a cold and snowy pattern like that of the last two winters would not unfold, more snow and cold would take place, with the total winter snow ending up closer to average. The latter scenario is not out of the possibilities, and could happen, although for now I am going with a less extreme change in the pattern given the situation the region is seeing.

Overall, however, the winter is likely to end up with above average temperatures and below average snowfall. The only snowstorm Central Park has seen so far, the late October snowstorm, places this winter's snow to date at 2.9 inches; assuming that some more cold and snow takes place, I am expecting this winter's snow totals to end up in the 13 to 22 inch range. At this time, it appears that the total may lean towards the lower end of this range, although I kept the higher end of the range near 22 inches accounting for the possibility that a colder and snowier pattern than currently expected does set up, in which case total winter snow may be near or possibly slightly above 22 inches, although at least with the latest indications, it appears unlikely that Central Park sees average snow this winter. More information on the medium to long range pattern will be posted with the daily updates throughout the month, along with a few updates in the "Long Range Forecasts" page.

Jan 6, 2012 Poll Results

Over the last month, three polls were open to vote on; one was about the most extreme weather event of 2011, and the other two were about this winter. Below are the results for these three polls:


How Much Snow Will NYC See This Winter? (53 votes)

8 votes - Less than 15 inches
5 votes - 15-20 inches
9 votes - 20-25 inches
7 votes - 25-30 inches (Average)
11 votes - 30-35 inches
1 vote - 35-40 inches
12 votes - 40+ inches


What Was The Most Extreme Event Of 2011? (77 votes)

46 votes - Hurricane Irene
18 votes - October 29-30 Snowstorm
7 votes - January 26-27 blizzard
3 votes - January 11-12 blizzard
3 votes - March 6-11 flooding


When Will NYC See Its Next Snow? (33 votes)

10 votes - Before January 10
10 votes - January 10-20
2 votes - January 20-31
1 vote - February 1-15
10 votes - After February 15



Stay tuned for two more updates to the blog later today, the first discussing the outlook for the rest of this winter, with a discussion later tonight focusing about the storm for late next week.

Jan 5, 2012: New Year, Same Pattern

Note: The blog archive goes back through late December 2009. Considering this, there are posts back from last January with the same dates but with a completely different pattern, as last year's January had plenty of snow potentials at this time of the year, while right now there is still no snow to be found. When checking this website for the latest forecasts, it would be helpful to check the date of the post to confirm that it is from 2012, and not from January 2011.

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The strong cold spell that affected the region over the last few days was no exception to the pattern in place, and the cold quickly started to move out, with warmer temperatures observed today along with partly cloudy skies. High temperatures ended up in the lower 40s across most of the area, which is slightly warmer than average. Widespread record warmth was observed today in the north central US due to an unusually strong warm air mass for this time of the year, and as we have seen plenty of times this winter, the warmth will spread towards the East Coast, with temperatures surging back to 50 degrees in parts of the area for Friday and Saturday. Although temperatures will cool back down to the 40s next week with generally dry conditions, a storm is expected to affect the area around Thursday next week, bringing more rain, potentially heavy, across the region.


Tomorrow's Outlook:


With the temporary break from the stormy weather, dry conditions along with partly sunny skies will continue through the next 6 days, including tomorrow (Friday). Temperatures will be noticeably warmer than they were today with the warmth spreading east, with high temperatures reaching the mid to upper 40s inland and the upper 40s to lower 50s across the area. These temperatures are nearly 10 degrees warmer than average.


Saturday - Wednesday: Dry, Warmer Than Average


With a low pressure moving through the northern Northeast, a cool air mass will slowly slide south from Canada into the region, but no amplification is expected as the pattern remains very progressive. The last day of the brief surge of warmth will be on Saturday, with high temperatures once again reaching the mid to upper 40s inland and the upper 40s to lower 50s across the rest of the area. Temperatures will slightly cool down on Sunday with partly sunny skies again, along with highs in the lower to mid 40s across the area. The storm that was modeled a couple of days ago for Sunday is still gone, with not a single sign of any precipitation even affecting the region, although the models are showing a wave of low pressure moving through parts of the region on Monday. For now, I kept partly to mostly cloudy skies in place for Monday with highs again in the lower to mid 40s, although in the scenario that the wave comes further north, a few isolated showers at most could be possible, although the risk of rain is very low at this time. Mainly sunny skies will return for Tuesday with highs in the mid to possibly upper 40s, and Wednesday will bring similar temperatures with increasing clouds.


Thursday - Longer Range: Rain, Then Colder


A storm is expected to approach the region on Thursday, bringing the potential for widespread moderate rain across the region. There is uncertainty with the exact development of the storm this far out, although there is high confidence that a storm will affect the area around this time frame. The storm will be a cutoff low, with another low pressure closer to the northern US keeping the cold air stuck in Canada and the western US. As a result, with little cold air associated with this storm, rain is likely to be the primary precipitation type for the Mid Atlantic, the I-95 corridor, and parts of the Northeast. Some models show the potential for heavy rain out of this storm, although strong phasing like the ECM model showed a few days ago is not very likely given the pattern, and at least as of now, I am thinking that the storm generally follows the progressive pattern, moving out of the region and towards Greenland instead of completely phasing and sticking over the US for a longer period of time. The CMC shows the latter scenario, although the CMC has a bias where it amplifies storms too much, with that bias most likely coming into play with its latest 12z run. For now, I am going along with a scenario where the low pressure moves through the region, bringing widespread rain, possibly moderate to heavy, along with mild temperatures surging into the 40s and possibly near/slightly above 50 degrees in the warmer case scenario. The forecast could still change, however, so stay tuned for more information on the late week storm potential.

Once the storm moves out, temperatures are likely to briefly stay mild, although a trough is likely to move towards the region by next weekend. Specific details are uncertain due to the time range, although colder temperatures are likely by next weekend. Looking beyond the weekend into the longer range, there are some changes in the current pattern starting to unfold, most noticeably with a round of sudden stratospheric warming, although the pattern is still struggling to change to one that supports more cold and snow in the East, and at this rate, New York City is likely to go snowless through at least the 15th. The updated winter outlook will be posted tomorrow, discussing the pattern outlook for the rest of the winter including an updated snowfall outlook.

Jan 4, 2012: Next Seven Days Mild, Dry

The peak of the strong cold air mass took place today, with very cold temperatures this morning, in the 10s across the entire area. Interior areas were not as cold as expected, with temperatures staying in the upper 0s to lower 10s, although with the wind, wind chills were much colder, generally near to below zero across parts of the area. Cold high temperatures were observed again today, reaching the mid 20s inland, mid to upper 20s in the immediate NYC area, and the upper 20s in Long Island and southern Connecticut. A shortwave moving through the region is currently bringing snow showers to parts of the Mid Atlantic, although any snow tonight will stay to the south of the area.

Although this cold spell was much stronger than the previous ones so far this winter, it is no exception to the pattern in place, and is currently moving out, with temperatures already returning into the upper 30s across most of the area tomorrow, warming back into the upper 40s by Friday and Saturday, nearly 10 degrees warmer than average. Dry conditions will last through the first half of next week with above average temperatures still in place, although the temporary break from the storms will end late next week with the next storm potential for the region.

Tomorrow's Outlook:

With the cold air mass moving out, much warmer temperatures will begin to return into the region. Partly sunny skies are expected tomorrow with warmer high temperatures, reaching the upper 30s inland and the upper 30s to lower 40s across the rest of the area with west/WNW winds expected.

Friday - Wednesday: Dry, Warmer Than Average

With a low pressure moving through the northern parts of the Northeast, warmer temperatures are expected for Friday and Saturday, reaching the mid to upper 40s across the area on both days. Parts of the immediate NYC area may reach and/or slightly pass 50 degrees on either day. Partly sunny skies will continue for both days.

It originally appeared that there was a storm potential for Sunday, with the model guidance showing some sort of a storm affecting the region several days in a row. However, the storm unexpectedly disappeared from the model guidance last night, with no hint of a storm affecting the area other than the DGEX model. As a result, I removed the risk of rain in the forecast and went with partly cloudy skies for Sunday, although later forecasts could slightly increase cloud cover on Sunday. Temperatures will be colder, reaching the lower to mid 40s across the area for highs.

The general pattern will continue through Wednesday with temperatures still slightly warmer than average, reaching the lower to mid 40s for highs on Monday before warming back into the mid to upper 40s on Tuesday. Similar temperatures are expected on Wednesday with increasing cloud cover.

Late Week: Larger Storm Potential?

Considering that this is still a week away, there is uncertainty with the specific details of this time frame, although the model guidance for the last few days has been suggesting that a significant storm could be possible in this time frame. The overall set up is still unfavorable for snowstorms in the I-95 corridor, with no blocking yet and a generally progressive pattern, and the ECM and GFS models have been showing the potential for moderate to heavy rain along with briefly warmer temperatures in this time frame. Some snow is possible outside of the interior Northeast, although the best chance of snow is once again in the Northeast, and considering the pattern in place and the overall set up for this time frame, this storm is more likely to end up as rain than snow for the I-95 corridor. Regardless of what happens in this time frame, colder temperatures may return towards next weekend. Stay tuned for more information on this time frame.

Jan 3, 2012: Cold, Snow Showers Tomorrow

With an amplified set up over the region, the strongest trough so far this winter dropped into the region yesterday, producing widespread lake effect snows and colder temperatures in the area. As the arctic front moved through last night, widespread light snow showers affected parts of the area, especially north and west of NYC, this morning, with most locations receiving these flurries generally seeing a trace to a coating of snow. Although this morning's snow was very light, it is remarkable that some areas that received flurries today have not seen any snow at all throughout December. Central Park has seen its third snowless December on record, and has not officially recorded snow today. The two other years this has happened, 2006 and 1877, ended up with well below average snow for the entire winter; both winters, however, had most of their snows focused later into January and February. More on the impact the current pattern has on the rest of the winter will be posted with the updated winter outlook to be posted this Friday.

With the front behind the area, the area is now seeing the peak of the cold air mass, with 850mb temperatures near -20 degrees Celsius. As a result, temperatures will drop into the single digits across most of the area north and west of NYC, getting close to zero degrees inland. Along with breezy conditions, wind chills are expected to drop into the single digits across the entire area and below zero further north/west from NYC. Temperatures will quickly warm up late this week into the weekend, although another wave of low pressure will move through on Sunday, bringing another risk of rain, followed by slightly above average temperatures once again.


Tomorrow's Outlook:


After the very cold morning, temperatures will warm up by the afternoon into the mid 20s inland and the mid to upper 20s across the rest of the area. Mostly sunny skies are expected in the morning, although cloud cover will increase by the afternoon and evening hours as another shortwave approaches from the west. This shortwave will bring scattered snow showers across a larger part of the area for tomorrow evening into the overnight hours, with another dusting of snow possible. Due to the cloud cover and snow showers, temperatures will only slightly drop tomorrow night, remaining steady in the upper 10s to mid 20s across most of the area.


Thursday - Saturday: Back To Warmer Weather


The cold spell the region is seeing is only temporary, and will quickly be replaced by another approaching warmer air mass. Although there are still no large scale changes with the pattern as a result of this cold spell, the difference from the current pattern and the one in most of December is that the ridge in the southeastern US has significantly weakened. This ridge has been present through most of November and December, keeping storms to the north/west of the area along with persistent above average temperatures. Over the last week or so, however, the ridge has significantly weakened, and although some ridging in the southeastern US is expected over the next 1-2 weeks, it will be weaker and less frequent than we have previously seen; as a result, temperatures from January 5, when the cold spell ends, through about January 15, will still likely end up slightly above average, but not as mild as December has been, with more frequent cool spells and troughs in the region.

One of these brief warm spells will affect the region late this week into the weekend, with temperatures warming back up into the upper 30s to lower 40s on Thursday. Partly sunny skies will continue through Saturday with high temperatures warming into the mid to upper 40s across the area on Friday, with slightly warmer temperatures possible for Saturday, reaching the upper 40s to lower 50s across most of the area.


Sunday - Next Week: Colder, Stormier?


A wave of low pressure is expected to move into the region on Sunday as a colder air mass returns. There is uncertainty with the storm, with impacts ranging from the GFS showing a weak storm with scattered light precipitation, the CMC showing moderate rain, and the ECM showing a significant storm with moderate to locally heavy rain along with heavy snows in the Northeast. Given this pattern, no significant amplification is expected with any storm that comes through, and the ECM's solution appears to be too extreme given this set up, although not completely impossible. For now, I am siding with a scenario where the wave of low pressure moves through, bringing light to moderate rain for Sunday with temperatures in the 40s, although it is possible that the storm ends up stronger with more rain, or weaker with isolated precipitation. Stay tuned for more information on this storm.

After Sunday, colder temperatures will briefly return into the region, although the models are showing the potential for another storm towards the end of next week. The ECMWF shows an intense storm moving through the region, while the GFS is still showing a range of different solutions but most of them siding with a weak storm. While details are still uncertain, the potential is there for rain to affect the area towards the second half of next week, followed by colder temperatures towards next weekend. Some snow could be possible if the storm takes a track supportive of such a scenario, although given the pattern in place, the Northeast is still favored over the area for any decent snow event. Stay tuned for more information on next week's outlook.

Jan 2, 2012 Noon Update

3:55 PM: Lake Effect Snow Showers


With yesterday's cold front out of the region, bringing widespread light to moderate rain across the area in the evening hours, widespread lake effect snow squalls have developed across the region. These squalls are focused over the typical lake effect snow areas, in New York and central/western Pennsylvania, although isolated snow showers are likely to affect the western parts of the area through tonight and into Tuesday, especially focusing over northern New Jersey west of NYC and SE New York.

A brief update will be posted later tonight on the upcoming significant cold spell. A longer discussion including an updated 5-day forecast will be posted tomorrow.