Special Weather Discussion

Latest Weather Discussion by Kyle Elliott

* pleasant and tranquil through start of meteorological summer *

11:30 a.m. Tuesday, May 26, 2026:

As expected, Memorial Day Weekend turned out to be cloudy, chilly, damp and dreary across the mid-Atlantic States. Saturday was a total washout across the Lower Susquehanna Valley, and Sunday wasn't much nicer despite a dry afternoon. On a positive note, the rainfall was much needed due to the moderate-to-severe drought in place across northern MD and southeastern PA. Most areas received 1.25-2.50" of rain from Friday afternoon through Sunday morning with locally higher amounts up to 3.0" south of the Mason-Dixon Line (see below). Fortunately, the easterly flow was replaced by light, westerly flow on Memorial Day, and Monday afternoon turned out to be mostly cloudy, humid and much warmer with highs in the 70s following a few morning showers. 

Much like yesterday, today will turn out partly-to-mostly cloudy and seasonable with highs in the mid 70s to low 80s from south-to-north across the region. An area of high pressure centered over the Poconos will suppress thicker cloud cover and any showers south of the Mason-Dixon Line this afternoon (see below). It won't be quite as humid as yesterday, though, with dewpoints ranging from the low-to-mid 50s north of the Turnpike to low-to-mid 60s across northern MD. 

A quasi-stationary frontal boundary is currently draped across the southern mid-Atlantic States, and a disturbance will move eastward along it through the Delmarva Region later tonight into Wednesday. A few showers may graze the southern-tier counties of PA between 1 AM and 1 PM Wednesday, but heavier downpours and thunderstorms will likely remain south of the Mason-Dixon Line and perhaps even I-70 tomorrow. Most of the afternoon should be mostly cloudy and dry, but humid, with dewpoints in the mid-to-upper 60s and a temperature distribution similar to today. Due to the clouds, showers and high humidity, tonight will be unseasonably warm with lows in the 60s. Rainfall amounts through Wednesday afternoon are uncertain at this time, but the most likely outcome is for very little rain north of I-76, 0.25" or less between I-76 and the Mason-Dixon Line, and up to 0.50-0.75" near I-70 (see below). Grab an umbrella and rain gear before heading out the door to work or school tomorrow, but you shouldn't need them by the PM commute. Overall, the weather during the middle of this week will be quite "normal" by late-May standards.

In the wake of Wednesday's disturbance, a Canadian high pressure system will settle into the northern Great Lakes region on Thursday. At the same time, a weak cold front will sag southward through the Commonwealth later Wednesday night into Thursday morning. Behind it, north-northwesterly winds of 10-20 mph will usher slightly cooler and much drier air into the Lower Susquehanna Valley. As a result, skies will gradually clear late Wednesday night, and Thursday is expected to be mostly sunny and beautiful with highs in the mid-to-upper 70s and dewpoints in the 50s. Wednesday night will still be rather warm and humid with lows and dewpoints in the upper 50s to mid 60s, but that humidity will go out of the air Thursday morning. The aforementioned high pressure system will then shift into the Ohio Valley and eastern Great Lakes region by the end of the week and promote a beautiful Friday with low humidity. After a mainly clear and crisp Thursday night with lows around 50°F, high temperatures should reach the mid 70s Friday afternoon under sunny skies. Winds will be light, as well, making it the perfect day for outdoor activities in shorts and t-shirts.

Looking ahead into the upcoming weekend and start of June, there are no more 90-degree days on the horizon. An "Omega Block".. or weather pattern featuring a massive, Jet Stream ridge sandwiched between two Jet Stream troughs.. will develop across North America late this week and persist into early June. In this case, the Jet Stream ridge will extend from Central Canada through the Northern Plains and Upper Midwest with the two troughs centered over New England and the Four Corners Region. On the southeastern side of the ridge and backside of the New England trough, persistent, northwesterly flow out of Canada will keep heat at bay and relatively cool conditions locked in place across the Eastern United States through at least the first week of June (see below).

A potent disturbance will move through northern New England from Friday night into Saturday, and a weak cold front extending to its southwest will likely move through the Commonwealth sometime on Saturday. Large-scale subsidence, or sinking motion, on the southwestern periphery of the disturbance and upper-level low should prevent all but a stray shower or two from accompanying the cold frontal passage. Instead, skies will likely be partly-to-mostly sunny on Saturday, and high temperatures will depend on the front's timing. In the event of a Saturday morning frontal passage, highs would only be in the upper 60s to low 70s. However, they'd be in the upper 70s or even low 80s with a late-afternoon or evening frontal passage. At this point, a "middle ground solution" is the most likely outcome.. i.e. an early-to-mid afternoon frontal passage with highs in the mid 70s and increasingly breezy conditions throughout the day. Behind the front, an even cooler and drier air mass will settle into the mid-Atlantic States during the second half of the weekend, and low temperatures could bottom out in the upper 40s early Sunday morning. That being said, the sun is nearly at its highest point in the sky across the Northern Hemisphere, so temperatures should still rebound quickly Sunday morning and peak in the the low 70s Sunday afternoon under mostly sunny skies. Overall, the weekend looks spectacular for outdoor activities and sleeping with the windows wide open at night. Humidity will be about as low as it can be in late May, and winds should be light again on Sunday. If only that had been the case over Memorial Day Weekend..

The forecast then becomes rife with uncertainty early next week. Some numerical computer models show two disturbances joining forces along the mid-Atlantic coastline and creating another wind-driven rain for the first day or two of Meteorological Summer. If so, then June 1st would feel nothing like the season with highs in the 50s or 60s. However, other models simply show a continuation of northwesterly flow and the two disturbances remaining separate from one another. Given early-June climatology, I favor the latter solution and expect a partly sunny, dry and pleasantly cool start to next week with highs in the upper 60s to mid 70s and lows in the upper 40s to mid 50s on Monday and Tuesday. However, it would be foolish to discount the first solution at this distance, so I'll keep an eye on trends this week. Check back Friday for a more confident forecast! -- Elliott