Monday, February 11, 2013

Feb 11, 2013: Two Storms Coming Up


Forecast Highlights:

After moderate rain fell this morning with freezing rain west and north of NYC, the storm moved out faster than expected, with widespread fog and temperatures in the upper 30s to mid 40s currently observed across the area. An active pattern continues for the region going into the medium range; despite just having gone through a blizzard on Friday, two more storms are coming up; a moderate snowstorm for Wednesday night, and the potential for another storm next weekend.





Tonight - Thursday: Near-Warmer Than Average; Weds Night Snow

Following this morning's rain event, temperatures returned into the upper 30s to mid 40s, with temperatures expected to remain near to slightly warmer than average, roughly around the same range, for highs through Thursday. Partly sunny skies are expected for Tuesday and Wednesday, with cloud cover increasing towards Wednesday afternoon and evening.

The next storm will affect the region on Wednesday night with additional snow expected. Over the last few days, the GFS model has consistently shown a moderate snowstorm affecting the area while the rest of the models, including the ECM, were much further south; since last night's update, however, the majority of the models have trended to the north, with a consensus emerging for light to moderate snow accumulations in the northern Mid Atlantic into southern Northeast region. An intensifying low pressure will track off the Mid Atlantic coast, bringing widespread snow into the region. This storm is associated with a marginal cold air mass, as temperatures leading up to this event peak in the upper 30s and 40s on Wednesday afternoon, with a lack of a high pressure to the north of the storm and a supply of stronger cold air, resulting in snow generally falling with temperatures near to slightly below freezing.

The current forecast is for snow to develop on Wednesday evening, possibly mixing with rain initially, which then changes over to several hours of moderate snow through the overnight hours, ending by early Thursday morning. Preliminary snow forecast at this time is for 3 to 6 inches of snow across the area, with the highest amounts west of NYC. The heaviest snow from this storm is currently likely to be a little south of the area, towards central PA and NJ, where amounts are likely to end up closer to 6 inches. More information will be posted on this with Tuesday's forecast discussion.


Friday - Weekend: Mild, Then Cold With Storm Potential

A cold front will move through the region on Friday night, with mild temperatures briefly returning for Friday. At this time, I sided warmer than the model guidance with high temperatures peaking in the mid to upper 40s across the area, potentially approaching 50 southwest of NYC. Slightly cooler temperatures will then return for Saturday ahead of the next storm potential towards Saturday night and Sunday.

As of yesterday, most of the models showed either scattered snow showers or a low pressure well offshore, although there were occasional hints of a more significant storm; today's model guidance partially trended this way, with the CMC and UKMET models showing a significant storm affecting the region. The ECM still has generally scattered snow showers, while the GFS has been more variable, ranging from a very strong storm on the 6z run to a mostly offshore snowstorm on the 18z run. Considering that this is still 5-6 days away, additional changes are expected with the model guidance; it is possible that any storm that develops stays too far east to affect the region, but the potential remains for this storm to affect the region. More information will be posted on this potential as details become clearer.

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