The past couple of days have provided a classic fall feel across the region, but changes loom.
The PNA (Pacific North America Pattern) is forecast negative- at times, strongly so- through the better part of the first half of October.
Accordingly, we would expect to see a deep trough across the west and ridging/ associated warmer pattern across the east. Sure enough, that’s what the modeling is painting.
A prolonged stretch of unseasonably warm and humid weather will be with us through the first couple weeks of the month. Unfortunately, for fall foliage enthusiasts, for the second straight year, this will have a negative impact on the peak color season. Highs in the middle 80s and lows in the upper 60s to around 70° will be common during the period. Summer isn’t finished yet…
The frontal boundary will sweep through the state late Tuesday and allow a cooler and drier air mass to filter into the region Wednesday. You’ll notice a true fall feel out the door Wednesday morning- low to mid 50s. Highs Wednesday afternoon will remain in the 60s.
The culprit? A persistent strong eastern ridge (the same ridge that trapped Florence across the Carolinas after she made landfall).
A positive PNA typically leads to an eastern trough- especially during the fall months into the spring. Something like this kind of upper level pattern usually results.
Sure enough, the models are going to this look.
At the surface, the eastern warmth is reversed in a significant fashion with well below average temperatures. In fact, temperatures will grow cold enough to support high ground snow in the Rockies and northern Great Lakes and the threat of an early frost into the upper Mid West and perhaps portions of the Ohio Valley during the period.
Ah, true pumpkin spice season is right around the corner. 😉