Feb 4, 2012: Relatively Quiet Week Ahead

Forecast Highlights:


- Light snow stays south tonight
- 50+ Degrees return briefly for the early week
- Scattered rain/snow showers Wednesday night
- Colder next weekend; storm possibility?


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As the radar to the left shows, a weak storm is currently affecting the central Mid Atlantic region with moderate snow and light accumulations in southern PA, while the area is still dry and cloudy. With the precipitation shield sinking south due to a high pressure over the region, the area will stay dry with no precipitation out of this storm. Temperatures today were chilly yet still noticeably warmer than average across the area, peaking in the mid 40s for most places.

With the storm moving out tonight, skies will clear by tomorrow with slightly cooler temperatures, although a warmer start to next week is expected, with temperatures once again passing 50 degrees in parts of, if not most of the area for Monday. Most of next week will be quiet in terms of storm activity, although there are two potentials for precipitation showing up, first in the form of scattered rain/snow showers on Wednesday night, and then as another potential storm for parts of the region next weekend.


Tomorrow - Tuesday Outlook


With the storm moving out of the region, mostly sunny skies are expected for tomorrow (Sunday), with temperatures similar to those of today, reaching the lower to mid 40s across the area. A light NW wind is expected.

Temperatures will warm up for Monday with partly sunny skies expected, with highs reaching the upper 40s to lower 50s across the area. In the warmer case scenario, places near NYC may get close to 55 degrees. A cold front will approach the region on Tuesday, bringing slightly cooler but still mild temperatures, in the upper 40s across most of the area.


Wednesday - Friday: Slightly Cooler, Light Rain/Snow Possible


With the Alaskan polar vortex displaced and ridging establishing itself temporarily in the western US and western Canada, cooler temperatures will gradually move towards the region during the second half of next week. It appears that a weak shortwave will move through the region on Wednesday night into Thursday, bringing widespread scattered precipitation across the region including the area. 850mb temperatures are supportive of snow, although surface temperatures are mild, modeled to end up around the mid 30s for NYC. As a result, I went with a light rain/snow mix for the 5-day forecast, although the forecast for Wednesday night is subject to slight changes. Temperatures will slightly warm up for Thursday, reaching the mid to upper 40s, before slightly cooling down on Friday back into the lower to mid 40s.


Next Weekend: Storm Potential?


As mentioned over the last couple of days, the displacement of the Alaskan polar vortex, replaced with a large ridge, and the polar vortex becoming displaced into southern Canada, a slightly colder pattern will briefly develop for the weekend, possibly into the start of the week afterwards. The trough axis is located in a position where should a shortwave approach from the southern US to phase with the northern stream, it would be more likely than previous storms this winter to be in a favorable location to produce snow closer to the I-95 corridor and the coast. At this time, the probability of a large phase is low, especially with the cutoff low expected to end up near Baja California expected to drift south, with the more likely result at this time a late developing storm staying offshore and scattered precipitation in the region associated with the cold front. Some models, however, have shown a weak storm, especially the 18z GFS which had light rain/snow for the area. There is still uncertainty with this time frame and the models are likely to have a hard time handling this time frame, however, with several energies slowly drifting near the western US. While at this time, a significant snowstorm is not very likely, there is plenty of time for the solutions on the model guidance to change, and the result may either be a cold and dry scenario, or a scenario where a stronger coastal storm or a slightly inland storm affects the region with rain and/or snow. Stay tuned for more information on the weekend outlook.


Longer Range: Beyond the weekend, the western ridging is expected to significantly weaken; despite this, however, a negative NAO finally develops with stronger ridging likely near Greenland, a factor that has been missing for almost the entire winter. The pattern is likely to moderate, especially due to the weaker western US ridge and the polar vortex starting to drift back north, but the overall time frame for the second half of the month at least from the latest indications does not appear to be as warm as the late January to early February time frame, and at least one snowstorm is possible in the second half of the month should the -NAO become a more dominant aspect of the pattern. More information on the long range will be posted sometime this coming week in the Long Range Outlooks page.