Technical Forecast Discussion
Synopsis:
The temperatures will remain cool despite the sunny conditions on Tuesday. Some clouds will start to move in late Tuesday night as a storm system approaches from the Midwest. Wednesday features a possibly for some rain/snow showers due to the aforementioned storm system passes to our south. The showers may continue into Wednesday night and gradually taper off. However, the clouds shall linger throughout much of Thursday with some wintry precipitation finding their way back into the Commonwealth again as another storm system develops along the southeast coast on Friday.
Short-term (Tuesday – Wednesday night)
A high pressure ridge situated over the Great Lakes will continue to usher in cold air from Canada on Tuesday. Despite the emergence of a vorticity maxima near the 500-mb level and spotty low-level moisture, the skies shall remain sunny to mostly sunny for much of the day on Tuesday. Some clouds may start to move in later Tuesday night as a 500-mb shortwave races across the Midwest toward the east coast. Its associated surface low pressure system will throw some moisture into the region, but the models do not show any substantial precipitation to enter the region until Wednesday. Wednesday will feature mostly cloudy skies with a slight chance of rain/snow showers. Any precipitation shall end Wednesday night but clouds will linger over the region.
Mid-term (Thursday – Thursday night)
Thursday will be the break in between two storm systems. The 500-mb shortwave will slide offshore on Thursday, but it will leave some low level moisture behind. Another upper level energy will quickly follow the existing storm system, which will give us another chance of wintry precipitation starting Thursday night.
Long-term (Friday – Saturday)
The models diverge quiet a bit at this point concerning the timing and the formation of the second storm. It seems like the models are still having trouble handling this second piece of upper energy swinging across the central states. First, let's talk about the GFS. The 12Z GFS depicts an area of PVA crashing into the Central Plains on late Thursday night. However, it breaks off another shortwave energy ahead of the amplifying trough, which will spun a weak coast low just offshore South Carolina. The main piece of energy lags behind, but will eventually merge with the first coastal low after crossing the Tennessee Valley on Friday. The two lows will combine into a bigger system but still not too strong in terms of intensity. Expect the main bulk of precipitation confined along the coastal regions if this scenario is true. The WRF also a weak shortwave forming ahead of the much stronger shortwave, but it keeps the shortwave on the weaker side, thus a weaker initial coastal low. This may benefit main storm to intensify stronger once it hits the coastal waters, but the true outcome remains to be seem. The UKMET model is on the extreme side of the solution with a very sharp 500-mb trough to start with. The trough becomes more negatively tilted as it approaches the east coast, eventually close off into a closed 500-mb low once it reaches the Northeast coast. This scenario would spin up a very robust coastal storm, possibly a late-season nor'easter, which will dump large quantities of precipitation to parts of the Northeast. The precipitation type is still uncertain as of now, but we cannot rule out the possibly of some places seeing blizzard conditions this upcoming weekend. However, the main point is that the models do not have a general agreement at this time.
David Wang
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