Special Weather Discussion

Latest Weather Discussion by Kyle Elliott

* Warmer this weekend with gusty showers sunday night *

11:30 a.m. Friday, October 17, 2025, Update:

As expected, frost only developed in rural/outlying areas and deeper valleys across northern MD and south-central PA early this morning. Following a cold start with lows of 32°F at York Airport, 35°F at Lancaster Airport and 36°F at Millersville University, this afternoon will turn out quite nice with highs in the low-to-mid 60s.. just a few degrees below average.. under sunny skies (see below). The high pressure system currently centered over the mid-Atlantic States will shift into the western Atlantic this weekend. On its backside, southerly flow will usher milder air into the region Saturday afternoon with highs in the upper 60s to low 70s. Tonight will still be chilly with lows around 40°F under mainly clear skies, but temperatures should rebound quickly tomorrow morning and reach 60°F by noon. After a calm and comfortably cool Saturday night with lows in the mid 40s to perhaps 50°F, the southerly winds will strengthen on Sunday and gust up to 35 mph at times in advance of an approaching cold front. Thus, even warmer conditions are expected with high temperatures around 10°F above average (mid 70s) in most locations (see below). Sunshine will be filtered through high clouds both Saturday and Sunday, but clouds should not lower and thicken until the late-afternoon or early-evening hours on Sunday. As a result, the weather will be ideal for outdoor activities this weekend with virtually no chance of rain until Sunday evening. Gusty winds may blow loose objects, trash cans and holiday decorations around on Sunday, so make sure those are secure and be alert for their presence on walks, runs, bike rides, etc. 

The aforementioned cold front will traverse the Commonwealth from west-to-east spanning Sunday afternoon to Monday morning and bring showers to northern MD, southeastern PA and the Lower Susquehanna Valley during that time. Showers probably won't reach western parts of the Valley until 6-8 PM and eastern areas until 8-10 PM, and most of the activity will occur overnight. Despite the time of year and timing of the rain, there will be a lot of energy associated with this potent front. Thus, I expect the most intense showers to contain brief, torrential downpours, wind gusts up to 45 mph and even a few rumbles of thunder. It shouldn't rain for more than 4-6 hours in any location, so amounts still appear light and generally below 0.50" (see below). Due to the abnormally dry conditions in place, the rain will be most welcome and highly beneficial. At this point, I expect the front to push east of the I-95 corridor prior to sunrise, so wet roadways should be the only weather-related hazard during the Monday morning commute.

Behind the front, gusty, westerly winds of 12-25 mph with gusts up to 40 mph will direct cooler and drier air into the region Monday afternoon. However, high- and low temperatures will still be "near normal" by late-October standards and in the low-to-mid 60s and low-to-mid 40s, respectively. A weak bubble of high pressure should settle into the region Monday night and cause winds to subside, but it will quickly shift into the western Atlantic. Much like tomorrow, winds will turn southerly Tuesday on the backside of the high, and high temperatures should climb back above normal and top out in the upper 60s to perhaps 70°F under partly sunny skies. However, the fast, zonal (west-to-east) flow across the country will lead to another cold frontal passage Tuesday night into Wednesday. Compared to Sunday night's front, the next one appears much weaker and more starved for moisture. Thus, I only expect a few light showers to accompany its passage, but gusty, westerly winds will usher another shot of cooler air into the mid-Atlantic States next Wednesday/Thursday. High temperatures will likely peel back into the upper 50s or low 60s both days, and the strong winds will make the outdoor air feel even chillier. Needless to say, 80°F days are a thing of the past, and that "fall feeling" in the air is here to stay. -- Elliott

11:45 a.m. Tuesday, October 14, 2025: 

As anticipated, the "Nor'easter" was nothing more than a prolonged and drawn-out "nuisance event" across northern MD, southeastern PA and the Lower Susquehanna Valley. Other than a few showers and areas of drizzle Saturday night and Sunday evening, the weekend actually didn't turn out too bad with highs in the mid-to-upper 60s each afternoon. There weren't too many breaks of sun, but at least it was dry during the daylight hours. Monday turned out to be the only "downright nasty" one with the storm system centered just off the Delaware and New Jersey coastlines. Northerly winds of 12-25 mph accompanied periods of light rain and drizzle throughout the day, and temperatures were stuck in the chilly 50s due to the clouds and wet weather. From Saturday afternoon through early this morning, a general 0.25-0.75" of rain fell across the region with locally higher amounts up to 1.25" (see below). The rain was highly beneficial but probably not enough to influence the U.S. Drought Monitor locally.

The storm system has finally moved out-to-sea this morning and will continue to accelerate into the open waters of the central Atlantic during the middle of the week. In its wake, an area of high pressure over the Ohio Valley and central Appalachians will promote drier and warmer conditions today (see below). Clouds will give way to increasing amounts of sunshine this afternoon, and high temperatures will be back around average (near 70°F). After a mainly clear and comfortable Tuesday night with lows around 50°F, Wednesday will turn out mostly sunny and seasonable with highs in the mid-to-upper 60s. A moisture-starved cold front will then sweep through the Commonwealth from north-to-south Wednesday night, but not even a sprinkle will accompany its passage. Behind it, a Canadian high pressure system will settle into the eastern Great Lakes region on Thursday and bring cooler conditions to the Lower Susquehanna Valley. Despite abundant sunshine, high temperatures will be around 5°F below average Thursday afternoon and only in the low 60s.

A tight pressure gradient, or difference in pressure, between a Canadian high pressure system over the Great Lakes region and the storm system in the west-central Atlantic will be to blame for breezy conditions through Thursday. North-northwesterly winds of 10-20 mph with gusts up to 30 mph will be present each afternoon and then slacken/diminish each night (see below). The breeze will give the outdoor air an added chill on Thursday, so grab a jacket or sweatshirt before heading out the door to work or school. Temperatures will bottom out in the seasonably cool low-to-mid 40s Wednesday night and then the unseasonably cold mid-to-upper 30s Thursday night. The aforementioned high pressure system will settle into the mid-Atlantic States from Thursday night into Friday and cause winds to finally subside. The stage will be set for efficient, radiational cooling Thursday night, so expect another round of patchy frost in rural/outlying areas. Temperatures may bottom out between 32-34°F in the coldest spots early Friday morning, but I don't expect a freeze this go around. Bring tender plants/vegetation inside Thursday evening or apply a protective covering over them to prevent damage. Fortunately, temperatures will rebound quickly after sunrise and ultimately peak in the low-to-mid 60s Friday afternoon under mostly sunny skies. Overall, it'll be a nice end to the week by mid-October standards! Despite Thursday night's frost concerns, aggregate temperatures will still only be around 5°F below average late this week, so the cool shot certainly shouldn't make any headlines.

Looking ahead into the upcoming weekend, a warm front will move through the Commonwealth from southwest-to-northeast from Friday night into Saturday morning. In addition, the high pressure system will shift into the western Atlantic, and south-to-southwesterly flow on its backside will usher much warmer air into northern MD and southeastern PA. After a partly cloudy and cool Friday night with lows in the low-to-mid 40s, Saturday will turn noticeably milder with highs in the upper 60s to perhaps mid 70s. The unseasonably warm conditions should stick around through Saturday night and Sunday, as well, with lows in the low-to-mid 50s and highs in the mid 70s, respectively. However, breezy conditions will probably return on Sunday in advance of a potent cold front moving eastward from the Ohio Valley. Timing of that frontal passage is currently uncertain, but odds favor sometime between Sunday afternoon and Sunday night. Thus, you shouldn't have to worry about wet weather spoiling outdoor plans for most of the weekend. Showers or a period of steadier rain will likely accompany the cold front later Sunday and/or Sunday night, but rainfall amounts appear light at this distance and generally below 0.50". Behind the front, westerly winds of 15-30 mph will likely usher another shot of cooler and drier air into the mid-Atlantic States early next week, so high and low temperatures should peel back into the low-to-mid 60s and low-to-mid 40s, respectively. That's still right around average by late-October standards, though, and another brief burst of warmer air may follow next Wednesday/Thursday. Needless to say, aggregate temperatures through the end of next week will surely be at least a few degrees above normal. It's going to be awhile until persistently colder air arrives.. and I'm perfectly OK with that! -- Elliott