Special Weather Discussion

Latest Weather Discussion by Kyle Elliott

* a beautiful, summer weekend before storm chances return *

11:30 a.m. Friday, July 24, 2026, Update:

The weather over the last two days has been nothing short of spectacular! Following Wednesday morning's cold frontal passage, west-northwesterly winds of 12-25 mph ushered a cooler and much drier air mass into the Commonwealth. In fact, dewpoints plummeted into the 40s Thursday afternoon, and afternoon highs were in the refreshing upper 70s to low 80s under perfectly sunny skies. A sprawling high pressure system of Canadian origin was responsible for the beautiful weather, and it will continue to promote pleasant conditions through the weekend despite shifting into the Canadian Maritimes. This morning was the chilliest since June 3rd in many spots with lows of 49°F at York Airport, 53°F at Lancaster Airport, 54°F at Millersville University and 56°F at Harrisburg International Airport. However, temperatures rebounded quickly after sunrise, and afternoon highs will top out just a few degrees below normal under mostly sunny skies (see below). Humidity will remain low with dewpoints in the low-to-mid 50s, as well.

We'll be treated to a "repeat performance" of today's weather this weekend. With the high pressure system still in control, skies will stay mainly clear through Sunday night. The pressure gradient, or difference in pressure, over the region will also be very weak, so winds speeds should not exceed 4-8 mph each afternoon. Overall, the weather will be picture-perfect for outdoor activities and sleeping with the windows wide open at night! High temperatures will generally be in the mid 80s both Saturday and Sunday with overnight lows in the mid-to-upper 50s tonight, upper 50s to low 60s Saturday night, and low-to-mid 60s Sunday night (see below). Cooling demands will be well below average by late-July standards, and that's just what the weather doctor ordered after the brutal, early-month heatwave. Get outside and enjoy this early taste of autumn, but make sure to lather on the sunscreen!

The threat for showers and thunderstorms will return early next week, but the overall evolution, coverage, timing and intensity of the storms is still nebulous. A weak, upper-level disturbance along a surface warm front will likely trigger at least some showers and storms Monday afternoon. That being said, they will most certainly be widely scattered and remain below severe limits. Dewpoints will still only be in the low-to-mid 60s with light winds both at the surface and aloft. Thus, both wind shear and atmospheric moisture content will be low, so lightning and brief downpours will be the only real threats from Monday's storms. High temperatures should be similar to or just a couple degrees higher than Sunday and generally in the mid-to-upper 80s. 

Behind the warm front, winds will turn south-southwesterly from Monday night into Tuesday and pump hotter and more humid air into northern MD, southeastern PA and the Lower Susquehanna Valley. Dewpoints should surge back into the upper 60s to perhaps low 70s by Tuesday morning with highs in the mid 80s to perhaps 90°F Tuesday afternoon. However, a cold front will sweep through the Commonwealth from Tuesday afternoon into Tuesday night and put an abrupt end to the sultry conditions. In addition, it will trigger another round of showers and storms, primarily during the afternoon and evening hours, and be the culprit for our next severe weather threat. The system won't be as robust or potent as the last two, but the most intense storms will still produce locally damaging wind gusts, torrential downpours and small hail. Details surrounding the coverage of storms and extent of any severe weather will become clearer on Monday, so check back then for a video update! Regardless of the exact outcome on Tuesday, winds will turn northwesterly behind the frontal passage and usher another cooler and much drier air mass into the mid-Atlantic States during the second half of next week. An upper-level low trailing the surface cold front may keep clouds and the threat for a few showers in the forecast on Wednesday, but there should be big improvements in the weather late next week as another sprawling high pressure system settles into the region. If so, then July will go out on a mostly sunny and seasonably warm note next Thursday and Friday with high temperatures in the 80s and dewpoints back down in the 50s or low 60s. I'll take it! -- Elliott

1:00 p.m. Tuesday, July 21, 2026:

The week kicked off on a mostly sunny and pleasant note across northern MD and southeastern PA with high temperatures in the comfortable low-to-mid 80s Monday afternoon. Unfortunately, the tranquil conditions will be replaced by volatile weather and another round of severe storms this afternoon and evening. Much like Saturday, the Storm Prediction Center (SPC) has placed most of PA and the Delmarva Region in an "enhanced risk" for severe weather. A vigorous, upper-level disturbance and its associated storm system will sweep through southeastern Canada and New England over the 24-36 hours. To its south, a trailing cold front will serve as the "triggering mechanisms" for widespread showers and scattered strong-to-severe thunderstorms across the Lower Susquehanna Valley between 2-9 PM. This morning's round of showers and storms failed to materialize for most of the region, but "anvil blowoff" from Monday night's Ohio Valley thunderstorm complex, or "Mesoscale Convective System," overspread the region during the mid-morning hours and has since limited sunshine. Overall, this may be a good thing in terms of thunderstorm coverage through the rest of the afternoon and evening. The mid- and upper-level cloud deck may act as a "cap," or shield, to limit explosive thunderstorm develop and eventual coverage of severe weather (see below). Time will tell! 

With temperatures in the 80s and dewpoints in the low-to-mid 70s, the atmosphere will still be sufficiently moist and unstable for thunderstorm development and growth this afternoon. However, wind shear.. or a change in wind speed and/or direction with height above the ground.. will actually remain quite low across northern MD and south-central PA. Farther east, directional shear will be noticeably higher, so the threat for an isolated tornado or two should be greatest from eastern MD through DE, NJ and eastern PA (Philadelphia metro through the Lehigh Valley). Elsewhere, frequent lightning, torrential downpours and straight-line wind damage from gusts of 60-70 mph will be the main threats, but isolated incidents of large hail (>1" in diameter) also cannot be ruled out. Downed trees and powerlines, as well as power outages and roof damage, are all expected in hardest-hit areas (see below). In addition, rainfall rates will exceed 2" per hour in the heaviest storms, and areas hit repeatedly by torrential downpours could receive as much as 2-4" of rain. This flash flooding threat of low-lying, urban- and poor-drainage areas will generally be co-located with the higher risk for tornadoes. As such, a Flood Watch is in effect for far southeastern PA, northern DE and much of NJ through 2 AM Wednesday (see below). Have multiple ways to receive severe weather alerts and warnings through this evening, and seek shelter immediately in an interior room or basement if a warning is issued for your location! Be alert for standing water and debris on some roadways during the afternoon commute. The storms should push south/east of the I-95 corridor between 8-9 PM with no more than a lingering shower or two overnight. Overnight lows and dewpoints will generally be in the mid-to-upper 60s under mostly cloudy skies.. quite typical of late-July.

The aforementioned cold front won't actually move through the I-81 and I-95 corridors until Wednesday. That being said, it will probably be somewhere near I-95 by the early-afternoon hours, so any second round of storms should be confined to areas farther south/east. Other than an isolated shower, the day will generally turn out partly-to-mostly sunny and dry with high temperatures in the low 80s along I-81 to upper 80s from Baltimore to Philadelphia. Humidity will also drop rapidly during the afternoon hours in the wake of the frontal passage. Thereafter, we'll be treated to an extended stretch of mainly clear, dry, cooler and refreshing conditions from Thursday through the upcoming weekend. A high pressure system of Canadian origin will settle into the Ohio Valley and eastern Great Lakes region from Wednesday night into Thursday and then shift into the Northeast by Friday. It will slide into the Canadian Maritimes over the weekend but still remain in control of our weather. In the upper-levels of the atmosphere, a slight trough, or dip in the Jet Stream, will take shape over the Eastern States along the northern and eastern peripheries of a "heat down" in the Four Corners region (see below). The dry, northwesterly flow aloft will keep humidity low, aggregate temperatures around 5°F below average, and showers/thunderstorms at bay from Thursday-Sunday.

Overall, the weather will be perfect for outdoor activities and sleeping with the windows wide open at night. Some may even consider this an "early taste of autumn" with temperatures more typical of early-September than late-July. High temperatures will only be in the upper 70s on Thursday, low 80s on Friday, low-to-mid 80s Saturday, and mid 80s on Sunday. Dewpoints will hover in the 50s from Wednesday night through Saturday night and still not exceed the low-to-mid 60s Sunday into Monday. Best yet, overnight lows will be around 60°F Wednesday night and then bottom out in the mid-to-upper 50s Thursday, Friday and perhaps even Saturday nights. They'll rise early next week but may still end up in the seasonable low-to-mid 60s on Sunday and Monday nights. Not until Monday or Tuesday might another disturbance bring the threat for showers or storms back to the region. Details with regard to timing remain nebulous at this distance, but the disturbance should be much weaker than today's and fail to produce much, if any, severe weather. Check back Friday for an update! -- Elliott