Special Weather Discussion

Latest Weather Discussion by Kyle Elliott

* relatively tranquil and mild pattern until early next week *

11:30 a.m. Tuesday, November 4, 2025:

Halloween turned out blustery and rather chilly last Friday with wind gusts up to 45 mph and high temperatures in the upper 50s, but the weather over "Halloweekend" was fairly pleasant and quite typical of early November. An area of high pressure settled over the Commonwealth on Sunday and promoted light winds, mostly sunny skies and highs in the low-to-mid 60s. Winds increased again on Monday and gusted up to 30 mph at times during the late-afternoon and evening hours, and the blustery conditions are going to stick around through Thursday. However, the overall weather pattern will be relatively tranquil and mild through the second weekend of November. The only real threats for rain will be on Friday night and Sunday and occur in the form of scattered showers along and just ahead of two cold fronts. In the short term, an area of high pressure over the southeastern United States will bring sunny and seasonable conditions to northern MD, southeastern PA and the Lower Susquehanna Valley this afternoon with highs generally in the low 60s. Westerly winds will gust up to 30 mph at times through 2-3 PM before subsiding, albeit briefly, by the early-evening hours (see below). On Wednesday, winds will turn southwesterly ahead of an approaching cold front and increase throughout the day. They'll gust up to 30 mph again during the afternoon hours but also usher milder air into the region. After a seasonably cold Tuesday night with lows in the mid-to-upper 30s, high temperatures should peak in the mid 60s to perhaps low 70s (western half of the Valley) Wednesday afternoon.

The aforementioned cold front will then sweep through northern MD and southeastern PA Wednesday evening, but no more than a stray shower will accompany its passage. However, a 6-hour period of howling, northwesterly winds will follow immediately behind the front, and gusts could reach 45 mph at times between ~7 PM Wednesday and 1 AM Thursday. A tight pressure gradient, or difference in pressure, will linger across the mid-Atlantic States on Thursday, so northwesterly winds will still gust up to 30 mph during the daylight hours. The northwesterly flow will also direct a cooler and drier air mass into the Commonwealth, so high temperatures will fall back to around average and be in the mid-to-upper 50s. Another high pressure system will settle directly overhead Thursday night and finally cause winds to diminish completely, but low temperatures will plummet into the upper 20s (outlying areas) to mid 30s (urban centers) due to mainly clear skies, light winds and a very dry air mass in place. The area of high pressure will shift quickly into the western Atlantic on Friday. On its backside, a southerly breeze of 12-25 mph will begin to usher milder air into the region, but high temperatures will struggle to get above the upper 50s because of the cold start to the day. As discussed in the first paragraph, a weak cold front will then traverse the Commonwealth from west-to-east Friday night and bring a few showers to the Lower Susquehanna Valley. Rainfall amounts appear light at this distance and on the order of 0.10-0.20" or less, and showers should already have exited southeastern PA by daybreak Saturday. Due to the clouds and showers, low temperatures will be around 10-15 degrees above normal Friday night and generally in the mid-to-upper 40s. Better yet, the air mass behind the front will actually be slightly milder than the one ahead of it, so high temperatures should be in the low 60s Saturday afternoon under partly sunny skies (see below). Overall, it will be an ideal start to the weekend for outdoor activities, and you may even be able to shed the jackets or sweatshirts Saturday afternoon. No complaints here!

A second, much stronger and more potent cold front is then expected to move through the mid-Atlantic States on Sunday. It will be starved for moisture and, therefore, just be accompanied by another round of scattered showers. However, northwesterly winds behind it will draw a cold, Canadian air mass southward into the Central and Eastern States early next week, and high temperatures will likely fail to reach the 50-degree mark both Monday and Tuesday. Factor in the blustery conditions, and wind chills may be stuck in the 30s both afternoons and bottom out in the 20s at night. A deep trough, or dip in the Jet Stream, will amplify over the eastern half of the nation in response to a pronounced ridge over western North America. This large-scale pattern reversal will be the culprit for the unseasonably cold start to the week, and I won't even rule out the first flakes of the season in a few parts of south-central PA. Fortunately, this first "taste of winter" won't last too long, and a significant warming trend should commence by the middle to latter part of the week. That being said, you will definitely need to break out the winter coats and gloves for 2-3 days. Consider it a harbinger of things to come.. -- Elliott