Feb 4: Weekend Storm Update, Preliminary Snow Map

Verification For Wednesday Night: I expected Partly Cloudy skies, with low temperatures in the upper 10s to lower 20s north and west of NYC, in the lower to mid 20s for the north and west suburbs, and in the mid to upper 20s for NYC and closer to the coast. The forecast was too cold in the north and west areas, in the lower to mid 20s, but everything else verified.
Score: 3/4

Verification For Today: I expected Mostly Sunny skies, with high temperatures in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast. The interior was slightly warmer, in the mid 30s, but everything else verified.
Score: 3/4


Tonight: Mostly Clear. Low temperatures will be in the lower to mid 10s north and west of NYC, in the mid to upper 10s for the north and west suburbs, and in the upper 10s to lower 20s for NYC and closer to the coast.

Tomorrow: Increasing Clouds. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast.

Tomorrow Night: Snow, mainly after 10 PM. Low temperatures will be in the upper 10s to lower 20s north and west of NYC, in the lower to mid 20s in the north and west suburbs of NYC, and in the mid 20s for NYC and closer to the coast.

Saturday: Snow. High temperatures will be in the mid to upper 20s across the area.

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Weekend Storm Update: Potentially Historic Blizzard for Mid Atlantic, Lighter Snowfall Further North

I will split this forecast into two parts: The first one will be my thoughts for the New York City Tri-State area (the areas that I usually cover in my forecasts), and the second part will be my thoughts for the rest of the Mid Atlantic, including a preliminary potential snow map.

New York City Area Forecast:

When I made my verification for yesterday morning's storm, I noted how the NAM has trended south. This trend did not end today, but it continued even further south. In its latest run (18z), it showed a dusting of snow at most for the area. Other models have also trended south, including the EURO, the SREF, and also the GGEM, which I think the GGEM could be the outlier as it only has 1-2 inches of snow in Philadelphia, which is likely to see way more than that. However, the GFS model has trended much further north, now showing our area with 0.5 to 0.75 inches of precipitation, or 5 to 7.5 inches of snow.

With the other models well to the south, I am not convinced about it coming too far north, but we do have a very big storm with a lot of moisture that the models may be handling incorrectly, and with a weak SE ridge in place, and if the polar vortex is weaker than expected, then I can see how the storm could trend much further north.

For now, there is still uncertainty but we are starting to get an idea of what this storm will bring to the area, so my first preliminary thought would be about 2 to 4 inches in Sussex/Orange Counties, 3 to 6 inches for northern New Jersey, and 4 to 8 inches for NYC and Long Island. These totals are subject to change, and will probably be different tomorrow when I make my final forecast for the storm.

Mid Atlantic Forecast And Snow Map:

We are seeing what could be remembered as the Blizzard of 2010 in the Mid Atlantic. Blizzard warnings have already been issued in southern NJ, and with near/over 2 inches of liquid possible, we could be looking at as much as 2 feet of snow, if not slightly higher, from Washington DC to Southern New Jersey.

As such, below is my preliminary snow map. These amounts are subject to change, and are not final yet. My final map will be made tomorrow.

Verification For This Morning's Storm

Below is my verification for all of my forecasts for the snowstorm from this morning.

**Note: To prevent confusion, the forecast verifications I do each morning are only for the forecasts that I made in my previous update. So if I said less than 1/2 inch on one day and 1-2 inches the second day, when making my forecast verification on the third day, I would only grade what I did on the previous day's forecast, which here would be the 1-2 inch call.

The 1-2 inches of snow (with some reports of 3-4 inches) that fell across the area this morning seem to have fallen a long time ago, especially considering that most of that snow melted across the region, except for the interior areas.

Long Range Verification: From the longer range, I originally expected a few rain or snow showers with this storm. The models then trended south, and I then expected a possible impact by rain or snow showers.

Shorter Range Verification: As the storm approached, I expected less than 1/2 inch in the area, with up to 1 inch south of NYC. That update was made before the models trended wetter. By yesterday morning, the models were showing 1 to 2.5 inches of snow in the area, so I increased my forecast to show 1-2 inches, which ended up being in the range of the final totals.

Overall, if I was to give myself a score on the forecasts, it would be a B+.

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New Update on Weekend Storm - Too Far South?

The 00z NAM model that just came out completely backed away from the original idea it had. It trended so far south that NYC does not even see any snow out of this storm. We will see what happens tomorrow, but with the rest of the models also not as far north as the NAM was earlier, the trends are really not looking good for any snowstorm potential.

Feb 3: Forecast For This Weekend

Verification for Tuesday Night: I expected Periods of snow, with low temperatures in the lower to mid 20s north and west of NYC, and in the mid to upper 20s for NYC and closer to the coast. I expected snow accumulations between 1 and 2 inches. The forecast was correct.
Score: 4/4

Verification for Today: I expected light snow ending in the morning, with high temperatures in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast. My forecast temperatures were slightly colder than the actual result, with places north and west of NYC in the mid 30s, while NYC was in the upper 30s to the lower 40s.
Score: 3/4


Tonight: Partly Cloudy. Low temperatures will be in the upper 10s to lower 20s north and west of NYC, in the lower to mid 20s for the north and west suburbs, and in the mid to upper 20s for NYC and closer to the coast.

Tomorrow: Mostly Sunny. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast.

Tomorrow Night: Mostly Clear. Low temperatures will be in the lower to mid 10s north and west of NYC, in the mid to upper 10s for the north and west suburbs, and in the upper 10s to lower 20s for NYC and closer to the coast.

Friday: Increasing Clouds. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast.

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Short Term Forecast (Wednesday Night to Friday):

Temperatures tonight will be quite chilly, in the upper 10s to lower 20s north and west of NYC, in the lower to mid 20s for the north and west suburbs, and in the mid to upper 20s for NYC and closer to the coast. Tomorrow will be a mainly sunny day, with high temperatures remaining near average, similar to today. Skies tomorrow night remain mostly clear, with lows being slightly colder than tonight. By Friday, we still get temperatures to warm up early in the day with partly sunny skies, though cloud cover then increases through the afternoon hours, with skies becoming cloudy by the late afternoon to early evening hours.

Forecast for the Upcoming Weekend:

The forecast for this weekend was a very difficult one to make. We could end up with anything from a disruptive heavy snowfall to a light snow accumulation that would be nothing unusual to the area. While I mentioned yesterday that the chances for this storm to impact us are becoming greater, today we are seeing an even greater model spread.

The majority of today's model runs have trended south, decreasing precipitation amounts for the area, with the GGEM only bringing a few flakes at best. The only model that continues to show a big snowstorm for the area is the NAM, which I think is too far north with its solution, considering almost every other model is to its south. Below is the 66 hour frame on the 18z NAM run (under the "850mb Temp, MSLP, 6hr Pcpn" section):

**For those who do not know how to read this map, the green, blue and purple are the areas where precipitation is shown to fall, with the following intensity scale:
Green = light/moderate
Blue = moderate/heavy
Purple = heavy
North of the southernmost blue line, frozen precipitation typically falls, with rain to the south of the blue line. A wintry mix usually happens near that line. In this case, we are well north of the blue line, meaning that any precipitation that does fall will be plain snow.**



As you can see, the NAM would show moderate/heavy snow over the area, with the storm tracking just ESE of Delaware. The total run would bring us between 0.75 and 1.25 inches of precipitation, which would be about 7.5 to 12.5 inches of snow. And this is the northernmost run, so I would put about 10 inches as our maximum potential snowfall at this time.

Now looking at the GFS, this model was further south than the NAM. The GFS is also faster than the NAM, so on its 18z run, on hour 66, the storm is already exiting the area on the GFS while it's in the middle of affecting the area on the NAM, so for comparison purposes I am going to show hour 60 of the GFS below:



It is very easy to tell that this is further south than the NAM showed. On the NAM, New York City would get 0.5 to 0.75 inches of precipitation in 6 hours during the height of the storm, while on the GFS, we only get 0.25 inches of precipitation in 6 hours during the height of the storm. The blue line is also further south on the GFS, well south of southern New Jersey, while the NAM has that line up to southern NJ. And the NAM tracked the storm east southeast of Delaware, when the GFS takes it just east of the Virginia/North Carolina border near the coast.

The total GFS run brings New York City 0.25 to 0.50 inches of precipitation which would be 2.5 to 5 inches of snow, compared to the NAM's 7.5 to 12.5 inches of snow. And considering that both of these runs are the two extremes, this puts our potential snow range between 3 and 10 inches of snow.

You can see the NAM, GFS, and some other weather models in their NWS page: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/.

At this time, I do think that the GFS is slightly underdone with precipitation amounts, and that we could end up seeing a tight precipitation gradient in the northern side of this storm (which happens to be us). That is something we've seen in the late December 09 storm, and also why New York City got 10-15 inches of snow while Bergen County, just to the northwest, ended up with 4-8 inches of snow. The NAM has also been a relatively accurate model this winter, and has correctly forecasted the late December storm before the other models caught on to its potential, so I would also not completely dismiss its solution.

Overall, at this time, I would go for something in between these two models. There is still a lot of uncertainty, so we have quite a big range at this time, which I would put at 3 to 10 inches of snow, with the average being 5 to 6 inches of snow. The rest of the Mid Atlantic could end up with a major to a potentially historic snowstorm, with over a foot of snow for Washington DC and Baltimore possible, but further north than that is still a question. So at this time, I think that we could end up with moderate snow accumulations for this storm, with 4 to 7 inches of snow possible, but remember, nothing is final yet, as there is still a big spread with the model solutions. Stay tuned for the next update tomorrow.

Longer Range Update:

Of course, we can't forget about the longer range. While I am focusing on this weekend for now, our next storm potential will be during the middle of next week, between Tuesday and Thursday. This storm also appears to track to our south with the more likely precipitation type being snow. There is still a lot of uncertainty for that time period, so I will begin focusing on this storm once we get past this weekend, which is when we should have a better idea of what this storm might do.

Feb 2, 2010: Accumulating Snow Tonight

Verification for Monday Night: I expected Partly Cloudy skies, with low temperatures in the mid to upper 10s north and west of NYC, and in the lower to mid 20s for NYC and closer to the coast. The forecast verified.
Score: 4/4

Verification for Today: I expected Mostly Cloudy skies, with high temperatures in the lower to mid 30s north and west of NYC, and in the mid 30s for NYC and closer to the coast. The forecast verified.
Score: 4/4


Tonight: Periods of snow. Low temperatures will be in the lower to mid 20s north and west of NYC, and in the mid to upper 20s for NYC and closer to the coast. Snow accumulations between 1 and 2 inches expected.

Tomorrow: Cloudy. Light snow ending in the morning. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast.

Tomorrow Night: Partly Cloudy. Low temperatures will be in the upper 10s to lower 20s north and west of NYC, and in the lower to mid 20s for the north and west suburbs, and in the mid to upper 20s for NYC and closer to the coast.

Thursday: Mostly Sunny. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast.

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Short Term Forecast (Tuesday to Thursday):

For tonight, a storm that will track to our south should affect our area, the first to do so since January 28. Places further south, such as Washington DC, should get a notable snow accumulation out of this storm, with 3 to 6 inches of snow expected, and our area should be in the northern side of this storm. The latest models trended further north than yesterday, and as a result, we would get a period of moderate snow overnight. Places north of NYC should end up with 1-2 inches of snow, while places south of NYC could potentially even have slightly more than 2 inches of snow.

The snow will end by Wednesday morning, with high temperatures in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast. Thursday will remain with near average temperatures, similar to Wednesday's temperatures.

Forecast for the Upcoming Weekend:

Friday will be similar to Thursday in terms of temperatures, in the 30s across the area, with dry conditions. Then comes our next uncertainty, for next weekend. We will have a storm forming to our south, stronger than Wednesday's storm. The current likely scenario appears to be a storm trying to move into the western side of the Appalachians, however it is prevented from doing so completely and forms a secondary low, with then becomes the main storm, off the coast of either South Carolina, North Carolina or Virginia.

The models have trended north since yesterday in terms of the storm's location. It now appears that even though we still have a few days until the storm and we still have uncertainty, our area is now becoming more likely to see some type of snow this weekend, but it's not certain yet. What we need to know at this time, if it does snow, is whether it will be light, moderate, heavy, or if we end up with mixing issues (with sleet/rain mixing). It is not yet possible to answer this question, but we can determine that while it is uncertain what this storm will do, the chances of the storm impacting our area as of now are better than they were yesterday. Stay tuned for more updates.

Snow Map for Tuesday Night, 2/1/2010

Map Created: February 1, 2010
Time Period: February 2-3, 2010
Precipitation Type: Snow

Storm set up: A relatively weak storm moving to our south will bring periods of light to moderate snow to the Mid Atlantic before exiting the region and going out to sea.

Details: The storm will move into the southern Mid Atlantic tomorrow, bringing with it a wintry mix of snow, sleet and rain to that region. Amounts will generally be in the 1 to 2 inch range. As the storm moves northeast, it will encounter colder air, resulting in light snow in the northern side of the storm. The snow could become moderate between Washington DC and Delaware/southern New Jersey, resulting in a zone of potentially 2 or more inches of snow. The storm will then start heading out to sea, with the heaviest snow out of the storm being offshore. Light snow is possible up to Boston and possibly even southeastern New Hampshire, where less than 1/2 inch of snow is possible.

Forecast for NYC Tri-State Area: Light snow will fall tomorrow night through Wednesday morning, with amounts generally between 1/2 and 1 inch of snow.

Feb 1: Wednesday, Sunday Possible Snows?

Verification For Saturday: I expected Cloudy skies with light snow showers south of NYC. I expected high temperatures to be in the upper 10s to lower 20s north and west of NYC, and in the lower to mid 20s for NYC and closer to the coast. While I made my forecast colder than what it appeared to be due to cloud cover, temperatures ended up being even lower than that, in the mid to upper 10s north and west of NYC, and in the upper 10s to lower 20s for NYC and closer to the coast.
Score: 3/4

Verification For Saturday Night: I expected Partly Cloudy skies, with low temperatures in the mid to upper 0s north and west of NYC, in the lower 10s for the north and west suburbs of NYC, and in the mid 10s for NYC and closer to the coast. Wind chills below 0 degrees are possible north and west of NYC. The forecast was correct.
Score: 4/4

Verification For Sunday : I expected Mostly Sunny skies, with high temperatures in the mid to upper 20s north and west of NYC, and in the upper 20s to lower 30s for NYC and closer to the coast. The forecast was correct.
Score: 4/4

Verification For Sunday Night: I expected Partly Cloudy skies, with low temperatures in the mid to upper 10s north and west of NYC, and in the upper 10s to lower 20s for NYC and closer to the coast. The interior was colder than my expectations, in the lower to mid 10s, while the coast was warmer, in the lower to mid 20s.
Score: 3/4

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Tonight: Partly Cloudy. Low temperatures will be in the mid to upper 10s north and west of NYC, and in the lower to mid 20s for NYC and closer to the coast.

Tomorrow: Mostly Cloudy. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid 30s for NYC and closer to the coast.

Tomorrow Night: Cloudy. Light snow, mainly after midnight. Low temperatures will be in the lower to mid 20s north and west of NYC, and in the mid to upper 20s for NYC and closer to the coast. Snow accumulations less than 1/2 inch expected.

Wednesday: Cloudy. Light snow ending in the morning. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast.

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Short Term Forecast (Monday to Wednesday):

Tonight will be still chilly, but not as cold as previous nights, with low temperatures in the mid to upper 10s north and west of NYC, and in the lower to mid 20s for NYC and closer to the coast. Tomorrow will have more clouds with temperatures in the lower to mid 30s across the area. By tomorrow night, however, a relatively weak storm that will track to our south might end up affecting the area. It will be far south enough to give places such as Washington DC and southern NJ a period of moderate snow with up to 1-2 inches of snow possible, but it's still a question if the storm makes it far north enough to affect our area. At this time, I think that we could get some light snow, with up to 1/2 inch.

Any snow that does fall will end by Wednesday morning, with high temperatures in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast.

Medium Range Forecast (Thursday to Sunday):

Thursday and Friday should end up being the warmest days of this week. High temperatures on both days will be no lower than the mid 30s, and some places near NYC could even pass 40 degrees once again, which is a relief after how cold it has been in the past few days. Low temperatures, however, will still remain cold, in the upper 10s to 20s.

Then comes our next uncertainty, for next weekend. Saturday should still be dry with high temperatures colder, back into the lower 30s, however we then have a storm forming to our south, stronger than Wednesday's storm. The models for this storm are not yet consistent, however there is an agreement that this storm should not be able to track too far north to bring us warmth and rain. The next question is, do we get snow or will it be too far south?

Looking at the latest model runs, the GGEM and EURO models have this far north enough to give us at least a moderate amount of snow. The other models, such as the GFS, take this to our south so that we stay dry. One model, the DGEX, did show 20+ inches for the area this morning, which I consider the outlier solution. It's still too early to go into more details, but at this time, I would give a 50-50 chance of us getting snow or staying dry for next Sunday.

Jan 30: Cold Weather Continues, Next Weekend Storm?

Verification For Friday Night: I expected Partly Cloudy skies, with low temperatures in the mid to upper 0s north and west of NYC, in the upper 0s to lower 10s for the north and west suburbs of NYC, and in the lower to mid 10s for NYC and closer to the coast. I expected wind chills below 0 degrees. The forecast verified.
Score: 4/4


Today: Cloudy, with light snow showers south of NYC. Very Cold. High temperatures will be in the upper 10s to lower 20s north and west of NYC, and in the lower to mid 20s for NYC and closer to the coast. Wind chills below 0 degrees are expected in the morning.

Tonight: Partly Cloudy. Very Cold. Low temperatures will be in the mid to upper 0s north and west of NYC, in the lower 10s for the north and west suburbs of NYC, and in the mid 10s for NYC and closer to the coast. Wind chills below 0 degrees are possible north and west of NYC.

Tomorrow: Mostly Sunny. High temperatures will be in the mid to upper 20s north and west of NYC, and in the upper 20s to lower 30s for NYC and closer to the coast.

Tomorrow Night: Partly Cloudy. Low temperatures will be in the mid to upper 10s north and west of NYC, and in the upper 10s to lower 20s for NYC and closer to the coast.

Monday: Mostly Sunny. Warmer. High temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast.

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Short Term Forecast (Saturday to Monday):

As I mentioned last night, there was some uncertainty with the storm, as it took a last minute north trend on the models. This north trend did slightly continue overnight, with one model, the CRAS, even showing moderate snow for the area. That is not too likely, as the air is too dry. Dew points are below 0 degrees while temperatures are in the single digits to lower 10s, and humidity is between 40 and 60 percent across the area. We'd want to see the dew point near the actual temperature in order for it to snow, and increasing humidity.

With this, here is my final forecast for today. North of I-80 should stay dry and mostly cloudy to cloudy with high temperatures in the upper 10s to lower 20s. NYC should stay cloudy with perhaps a snow shower or two possible, with high temperatures in the lower to mid 20s. South of NYC, cloudy skies with scattered snow showers are expected, with perhaps a brief period of light snow near the coast. And from south of Philadelphia to southern NJ, a steady period of light-moderate snow is likely, with 1-2 inches of snow expected.

Tonight will still be very cold, with low temperatures similar to this morning's temperatures. For tomorrow, mainly sunny skies return, with temperatures rising finally warming past the 30 degree mark in NYC and areas closer to the coast. Monday is even warmer, with high temperatures already in the lower to mid 30s north and west of NYC and in the mid to upper 30s for NYC and closer to the coast.

Medium Range Forecast (Tuesday to Friday):

On Tuesday, high temperatures will be in the lower to mid 30s north and west of NYC, and in the mid to upper 30s for NYC and closer to the coast. There is still some uncertainty for Wednesday, as the models trended slightly north with the weak storm's placement, bringing precipitation from southern NJ and further south. At this time, I think that Wednesday should be mostly cloudy with an isolated rain/snow shower possible. Thursday will have partly sunny skies with high temperatures still in the 30s. Friday could warm up some more, with high temperatures potentially returning into the 40s for some areas.

Next Weekend Potential Storm:

The models are still all over the place with the possible storm for next weekend. Overnight, we saw three completely different solutions, with the DGEX taking the storm through NYC, bringing us rain, the GGEM taking the storm through the benchmark bringing us a lot of snow, and the GFS barely even bringing precipitation into Virginia. Expect this variety of model solutions to continue for the short term, and only in about 2-3 days is when the models should probably start getting more consistent with their solutions. Due to the way how storms were this past month, I'd favor a suppressed storm track at this time than anything too close to bring us rain, but it's still too early to know for sure. Stay tuned for more updates.