Feb 13, 2013: Snow Tonight, Then Mild Friday

11 PM Update: Parts of the post regarding Friday night-Sat have been revised.

Forecast Highlights:

The first snowstorm to affect the region since the blizzard last Friday will produce some snow and rain across the area tonight, with totals generally up to 2 inches, locally higher. Mild temperatures will make a brief return, with highs reaching the low 50s across parts of the area on Friday. A strong surge of cold air will follow for the weekend, but will quickly give way to another storm early next week with rain and possibly snow.




Tonight’s Outlook: Some Snow, Rain

As the latest radar loop posted to the left shows, widespread moderate precipitation is currently falling across Pennsylvania and Maryland, starting to spread into New Jersey, associated with a 1000mb low pressure currently off the Virginia coast, which will continue to move ENE and intensify; this can be seen with the intensifying precipitation over Delaware and New Jersey.

The precipitation shield so far is stronger and more widespread than some of today’s model runs showed, with localized reports of up to 2 inches of snow under the heavier snow bands in Pennsylvania. In other parts of Pennsylvania, however, the snow has had trouble accumulating with marginal surface temperatures. The heaviest precipitation is expected to spread into southern and central New Jersey; this will have difficulty accumulating initially with the marginal surface temperatures, although an area of higher totals up to 2-3 inches, locally higher, is expected towards those areas.

The NYC area is expected to be near the northern end of the heavier precipitation; despite moderate to locally heavy snow currently over Pennsylvania, precipitation should weaken inland over the next few hours with an increased focus towards the coast as the coastal low pressure intensifies. Based on latest indications, most of the area should generally see up to 2 inches of snow, with locally higher totals above 2 inches in Long Island. Additional updates will be posted on Twitter, and should there be any changes to the forecast accumulations, they will be added into this post as well.

Thursday – Weekend: Mild, Then Cold

Updated at 11 PM

Following tonight’s storm, with a lack of an incoming cold air mass, seasonable to slightly warmer than average temperatures are expected to continue across the region for tomorrow, with partly sunny skies, highs in the low to mid 40s, and light SW winds generally under 10 mph. The warmest temperatures are expected on Friday, with partly sunny skies, SW winds at 5 to 15 mph, and highs peaking in the upper 40s to low 50s from NYC and further west and the mid to upper 40s in Long Island and southern CT. The warmest temperatures are expected in the immediate NYC area, with highs likely to end up in the 50-55 degree range.

Initially, the potential was there for a storm to affect the region over the weekend; there have been recurring signals with the long and medium range model guidance showing a significant nor’easter, although at this point this is no longer likely to occur with the best forcing too far east and too late for a major storm to develop close to the area. However, precipitation is still expected to affect the region but in a somewhat different form than what was originally indicated. A wave of low pressure is expected to develop along the cold front on Friday night, moving through the region as a stronger low pressure develops offshore on Saturday and Sunday approaching Atlantic Canada. There is still some uncertainty regarding exactly what happens, although at this time it appears an organized area of light to moderate precipitation may affect the region on Friday night into Saturday morning, intensifying as it heads towards eastern New England. At this time, I included light rain/snow changing to snow in the 5-day forecast, although this is still subject to change, with some of the latest model runs indicating potential for light snow accumulations.

The warmth will quickly be erased on Friday night with a cold front moving through, being replaced by a strong, albeit short lived, strong cold air mass. Saturday will have much colder with highs in the low to mid 30s across the area. Overnight lows are expected to drop into the mid to upper 10s for most locations west and north of NYC, with low-mid 20s in NYC and parts of Long Island, followed by highs on Sunday only reaching the upper 20s to low 30s. Colder overnight lows are expected with more widespread 10s across the area, approaching 10 degrees for interior parts of the area.

Next Week’s Outlook

The cold spell for the weekend will be short lived; by Monday, a SW flow will develop with highs peaking in the upper 20s to low 30s inland and the low to mid 30s for the rest of the area. The next storm will affect the region on Tuesday; this storm will have its origins further north, with a low pressure tracking through the northern US initially before approaching the region; by this point, some models develop a stronger low pressure overhead with moderate to heavy rain and interior snows, while others such as the ECM and the CMC, with the latter model having gone through a major upgrade today, show a weaker low pressure tracking north of the area with rain. Additional changes are still expected, however, and more information will be posted as details become clearer.

Additionally, there have been strong signals from the latest model guidance regarding a storm potential next Friday, with the GFS model remarkably consistent with this feature throughout the last few days. This is still approximately 9 days away, however, and as this coming weekend has shown, signals for a storm in the longer range do not always reflect to an actual storm the same way as originally modeled. At this time it is way too early to determine exactly what happens in this time frame, but this potential will continue to be monitored, and more information will be posted should the probability of a storm increase for this time frame.

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