Wednesday, February 10, 2021

Another Two Part Winter Event

The National Weather Service has posted a *Winter Weather Advisory* for most of the area for tonight into tomorrow. All indications are that a slug of snowfall will impact the area from this evening into tomorrow morning. That being said, most guidance has converged on lower snow totals than were seen as being possible earlier in the week. Even so, the Euro model still indicates a shot at low-end warning criteria. In general, I think the NWS call for 1-3 inches of snow tonight is solid. I think it could push into the 2-4 inch range in spots that get better snowfall rates. 

The second wave looks to miss the DC-Baltimore corridor to the south. However, it's not out of the range of possibilities for this to trend back north. This second part of the system would be from later on Thursday and into Friday. 

TL;DR - A general 1-3 inches for much of the area tonight into tomorrow. Roads may be dangerous for travel. Some areas could see a bit higher. The second wave is still uncertain but for now, looks to miss. 

Tuesday, February 9, 2021

Long Duration Winter Storm Possible

Confidence is high that winter weather will impact the region once again this week. Currently, it appears that snow will develop from west to east across the area on Wednesday afternoon or evening. There continues to be some model disagreement with regards to exact details. This storm system is actually two "waves," and one may become dominant while one reduce in intensity. For this reason, while the odds for winter precipitation are high, the confidence in the exact timing or amounts are less certain. 

The 06z NAM model run from early morning on 2/9. This shows the progression that this model thinks is possible for the winter weather event for Wed-Fri. (Source: Pivotal Weather)

The 06z RGEM model from early morning on 2/9. This shows another model's take on what may transpire with the storm system for Wed-Fri. (Source: Pivotal Weather)

The 06z GFS model run from early on 2/9. This is just another example of another forecast model trying to crunch the numbers to determine what may happen for our next winter storm. (Source: Pivotal Weather)

You can see from the above forecast model loops, that the timing and intensity varies from one model to the next. However, there is a good chance at 1" or more of snowfall areawide (with the usual exceptions perhaps being to the areas south and east of the metro corridor). I'd even go farther and say that the chance for 2" or more are also quite high. Beyond that, a lot will rely on how potent each of the waves turns out to be in reality. This could be yet another situation of a winter storm that has a slug of snow, a lull and then perhaps additional snowfall with wave two. 

There is a chance that this could be a 4-8" snowstorm when all is said and done. Some mixing will be possible to the south and east. 

Taking a blend of various models gives the area a very healthy snowstorm. For now...I'd forecast 2+ inches with this system and leave it at that until some additional clarity is given by short term forecasting. 

"National Blend of Models" product from Pivotal Weather. This is a blended map showing what a blend of various weather models thinks will occur. This *could* be on the high end IF the system becomes weaker than modeled.

Looking even further ahead...there appears to be winter storm threats (very low confidence forecast at this time) for the weekend and then again Tue/Wed of next week. There's some early indication that significant ice could be in play for the weekend system...but of course it is too early to say with any sort of certainty. 

The bottom line is that we should continue to see a parade of at least THREATS for winter storms. Whether these pan out remains to be seen. However, the pattern certainly supports continued attacks by Old Man Winter. I'll continue to keep you updated as each system gets closer in time.