Monday, February 1, 2021

Storm Winding Down - What's Next? [VIDEO]

Note from Pulse Weather: The video that goes along with this video is included both here, and at the bottom of this post for your convenience. The details in the text are covered in the video edition as well.

What's Next for DC's Winter? VIDEO

The current storm is starting to wind down across the area. I'll describe that storm system as a bit of an odd one. This particular type of storm is classified as something called a "Miller B" storm. Miller Bs are characterized by a primary low pressure system heading into the Ohio Valley and then redeveloping or transferring to the coast. Most of the time, the Washington, DC area tends to get a little "screwed" by these types of storms as they often develop the coastal just a little too late. 

Areas along the Mason-Dixon Line were treated to some great wraparound snowfall this afternoon. Totals there have really ramped up. Totals locally in Montgomery County and the DC/Baltimore area have been more tempered. It was an odd storm that spread light wintry precip out in a span of a few full days. 

Snowfall totals as shown by a map from the National Weather Service in Sterling, Virginia (LWX). This image is courtesy of their website. Click for full size image. 

Snow showers may continue through the night and into tomorrow in spots. Some gusty winds may also be  a factor - particularly to the north and east. 

So...What's next? [NOTE: A video is included at the bottom of this video for those not wanting to read a wall of text]

1) Moderating temperatures later in the week: Later this week, in the wake of our current storm system, temperatures will be able to rebound a bit into the 40s. This will be ahead of the next weather maker over the coming weekend. 

2) Significant dump of Arctic air with the potential for an associated batch of snow squalls: During the coming weekend, a significant batch of frigid air will come out of Canada and move eastward to impact the area. There's a chance that a secondary front behind the initial one could produce snow squalls similar to the Valentine's Day snow squalls in 2015. This is discussed in more detail in the video below. 

Robust shot of Arctic air shown dumping out of Canada on the 18z GFS model run. (Source: TropicalTidbits) - Click on the image for the full size. 

3) Storm system for the 2/8 or 2/9 timeframe: After the dump of Arctic air, a potential storm system will develop in the southern half of the country. Depending on the exact evolution of various upper level features, this storm system could pose a threat for significant winter weather in the area. Of course, being seven days out increases the amount of uncertainty. 

4) Follow up storm system for the period around 2/10: Immediately in the wake of the potential storm system for 2/8-9...another storm system may develop in the Gulf Coast states and track along the eastern seaboard. Being 10 or so days out significantly decreases confidence in any one model solution at this time - but this could pose a threat for follow-up winter weather for the region. 

All of these potential winter weather threats are due in part to a very favorable upper air pattern. A favorable -NAO block is forecast to be in place near Greenland. Of course, details will be easier to forecast as we get closer, but the threat is there for long lead winter storms. Occasionally, in this type of pattern, confidence can be higher from longer leads due to blocking and pattern stability. We'll see if things are more clear than they were with this most recent winter storm. 

500mb pattern as depicted by the GFS Ensembles from the 18z run on 2/1/2021. (Source: TropicalTidbits) - Click on the image for the full size. 

The big area of positive height anomalies shown near Greenland is what is referred to as a -NAO. Negative anomalies in this area would be a +NAO. There are other indices to monitor as well. The PNA and AO are other factor. Perhaps a winter storm hunter "crash course" would be an interesting post for the future. 

Check out the video that goes along with this latest post!

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