Special Weather Discussion

Latest Weather Discussion by Kyle Elliott

* typical august pattern with several shower chances through the weekend *

11:30 a.m. Tuesday, August 18, 2026:

The third week of August kicked off on a partly sunny, hot and humid note in advance of a weak cold front. High temperatures reached the upper 80s to low 90s Monday afternoon with dewpoints in the low-to-mid 70s and peak heat indices in the mid 90s. The front triggered scattered showers and a few drenching thunderstorms across the Lower Susquehanna Valley between 1-8 PM, but there were only a few reports of wind damage in Berks County. As is often the case in summertime convective environments, rainfall amounts varied greatly from neighborhood-to-neighborhood and county-to-county. Some areas received little if any measurable rain, while the hardest-hit ones picked up over an inch. Behind the front, north-northwesterly winds of 6-12 mph will usher slightly cooler and less humid air into the region this afternoon. Under partly-to-mostly sunny skies, high temperatures will be in the seasonably warm mid 80s with dewpoints in the mid 60s (see below). Tonight will be quite comfortable and ideal for sleeping with the windows open with lows in the low-to-mid 60s. An area of high pressure currently centered over the Ohio Valley will shift into the central Appalachians and mid-Atlantic States on Wednesday, so expect a repeat performance of today's weather. Skies should be mostly sunny and humidity relatively low with dewpoints in the low 60s. High temperatures will be similar to or just a bit higher than this afternoon and generally in the mid-to-upper 80s (see below).

Humidity will increase again Wednesday night, and dewpoints will likely be back in the upper 60s to low 70s on Thursday. In addition, a weak disturbance zipping from the Ohio Valley through the mid-Atlantic States may bring showers or periods of rain to northern MD and southeastern PA late Wednesday night through early Thursday evening. However, there is still some uncertainty with respect to its timing and track. That being said, odds favor any heavier thunderstorms remaining south/east of I-95 with little if any thunder at all north of the Mason-Dixon Line (see below). Due to the clouds and wet weather, high temperatures may struggle to reach 80°F across the southern half of PA Thursday afternoon. Grab an umbrella before heading out the door to work or school, and expect some travel delays and standing water on roadways. Rainfall amounts and their distribution will depend entirely on the exact track of the disturbance. 

Behind the system, a Canadian high pressure system will settle into northern New England on Friday and exert its influence down the eastern slopes of the Appalachians. As a result, skies should gradually clear Thursday night, and the week could very well end on a mostly sunny, less humid and beautiful note with high temperatures in the low 80s and dewpoints around 60°F. The forecast then becomes more uncertain over the weekend. Winds may turn east-to-southeasterly Saturday on the southwestern periphery of the aforementioned high pressure system, and that could draw clouds and moisture back into the Lower Susquehanna Valley. If so, then Saturday would likely turn out mostly cloudy and temperate but more humid with dewpoints back in the mid-to-upper 60s. At the same time, a cold front extending southward from a storm system over southeastern Canada will sweep through the mid-Atlantic States later Saturday into Sunday. Thus, more rounds of showers are a "good bet" from Saturday afternoon through at least Sunday morning, but their exact timing/intensity and any risk of thunderstorms are impossible to finesse at this distance. If the front sweeps through the I-81 and I-95 corridors later Saturday night or Sunday morning, then the second half of the weekend could turn out mostly sunny, pleasant and significantly less humid. However, a delayed frontal passage would probably spell another round of scattered showers and thunderstorms Sunday afternoon. Regardless, a deep trough, or dip in the Jet Stream, will likely settle over the Northeast and Great Lakes region early next week and promote mostly sunny, dry and pleasantly cool conditions on Monday and/or Tuesday. There are no more 90-degree days on the horizon, and I doubt many of you will be complaining about that! Check back Friday for an update. -- Elliott