12:30 p.m. Friday, May 9, 2025, Update: Despite copious amounts of rain between May 3-6, this week's U.S. Drought Monitor update still showed most of the Lower Susquehanna Valley and northern MD in moderate-to-severe drought (see below). However, that should change next week following the ongoing deluge. As expected, showers and locally heavy, drenching thunderstorms erupted last evening, and periods of steadier rain have been soaking the region this morning (see below). Most areas have received 0.50-1.50" of rain since Thursday afternoon, but as much as 3-4" has fallen in isolated pockets. Add it all up, and most of the region has already picked up a month's worth of rain.. or more.. in the first 9 days of May. With more rain ahead over the next two weeks, monthly rainfall totals will end up way above normal, and that will effectively put a major dent in or even wipe out the drought. Against all odds, a series of closed-off, upper-level lows.. not a tropical cyclone or return of El Niño.. will bring an end to the drought. Who would have thought it? Certainly not me! The slow-moving storm system responsible for the rain will lift into southeastern New England by tonight. Rain will continue to taper off from southwest-to-northeast this afternoon, and most areas should be dry by 5 PM. Remain alert for areas of standing water on roadways and flooding in low-lying, urban- and poor-drainage areas over the next few hours, and never drive through a flooded roadway. In addition, reduce speed on the wet roads to minimize the risk of hydroplaning and a vehicle accident. Keep an umbrella and jacket/sweatshirt handy, too. We get at least one day like this.. cloudy, damp, rainy, dreary and cold.. in May virtually every year. Temperatures will be nearly steady in the 50s all afternoon, and that's about 20°F below average in early May (see below). Fortunately, the weather will do a complete 180 just in time for Mother's Day Weekend! I love being the bearer of good news! In the wake of the storm system, skies will gradually clear tonight. Northwesterly winds of 10-20 mph with gusts up to 25 mph will then usher drier air into the Commonwealth on Saturday. A sprawling high pressure system over southeastern Canada will settle into the eastern Great Lakes region and Northeast by Mother's Day and shift into the western Atlantic early next week. The large-scale subsidence, or sinking motion, associated with the high will result in mostly sunny, dry and absolutely beautiful conditions over the holiday weekend! The weather should be nothing short of spectacular tomorrow for commencement activities at universities across the Commonwealth.. including the 171st Commencement Ceremonies at Millersville University. High temperatures will be in the upper 60s to low 70s following early-morning temperatures in the mid-to-upper 40s. Factor in plenty of sunshine, the refreshing breeze and 40-45°F dewpoints, and conditions will be great for pre- or post-graduation pictures with family and friends! The weather on Mother's Day will be virtually identical to and equally as gorgeous as tomorrow. High temperatures may be a few degrees above those on Saturday but still won't exceed the low-to-mid 70s, and winds won't exceed 10 mph (see below). The day will start on a seasonably cool note (mid-to-upper 40s), but temperatures will rise quickly during the morning hours. Thus, it's "all systems go" for outdoor activities with Mom on Sunday. You'll be able to sleep comfortably with the windows open all weekend long, as well, without having to worry about rain. Talk about an A+ weekend! Looking ahead into early next week, we will be treated to partly-to- mostly sunny, dry and pleasantly warm conditions for a 3rd-consecutive day (Monday). Low temperatures will be in the mid-to-upper 40s again Sunday night with highs in the mid-to-upper 70s on Monday. Humidity will still be low, as well, with dewpoints in the upper 40s or low 50s. Quite frankly, it's almost impossible to dial up a nicer stretch of weather than that from tomorrow through Monday. I hope you can get outside and take advantage of it! Unfortunately, clouds and the threat for showers or periods of steadier rain will return during the middle of the week. Yet another upper-level low is currently in the process of closing off, or becoming detached from, the Jet Stream over the Deep South. It will meander over the Southern States and Lower Mississippi Valley through Monday before finally lifting northeastward toward the Ohio Valley, central Appalachians and mid-Atlantic States. The system should weaken dramatically and "open back up" during the middle of next week, but it will take 2-3 days for the broad circulation to reach the western Atlantic. Thus, daily rounds of showers, batches of steadier rain and perhaps a few embedded thunderstorms will plague the Lower Susquehanna Valley from Tuesday- Thursday. The showers/rain will probably arrive later Monday night and be most widespread from Tuesday into Wednesday morning. Due to a lack of instability and the system's disorganization, I don't anticipate any severe weather next week, and rainfall rates/amounts should be much lower than May 3-6. However, a general 1-2" of additional rain seems like a "good bet" next week. It won't be a complete washout each day, but you'll need to keep an umbrella handy at all times. As is often the case in the late-spring and summer months, showers/storms will likely be most widespread during the afternoon and evening hours. Some areas will receive locally higher amounts of rain, while others get less. Persistently, southerly flow will pump Gulf- and Atlantic moisture into the region from Tuesday-Thursday, so dewpoints and overnight lows will be back in the 60s. Daytime highs will be confined to the upper 60s to mid 70s on account of the extensive cloud cover. In terms of continued drought relief, the rain will be a good thing. In terms of outdoor activities and Vitamin D, it will be a bad one. You be the judge! 😊 -- Elliott 6:00 pm. Tuesday, May 6, 2025: Multiple rounds of showers and locally violent thunderstorms have plagued northern MD, southeastern PA and the Lower Susquehanna Valley since Saturday. Against all odds, drought relief has come in the form of a closed-off, upper-level low meandering over the Ohio Valley and eastern Great Lakes region. To its east, south-to-southeasterly flow has drawn ample Gulf- and Atlantic moisture into the mid-Atlantic States, and most areas have received 1-3" of rain since late last week. As much as 6" of rain has fallen near the Adams-Franklin County line, effectively putting a major dent in the moderate-to-severe drought. In addition, severe thunderstorms in northern MD and the I-95 corridor were responsible for dozens of wind damage reports Saturday afternoon and evening, and an EF-0 tornado briefly touched down in Cocalico Township (Lancaster County) on Sunday. One final round of showers and heavy, drenching thunderstorms inundated the region this afternoon, but those have since lifted into northeastern PA. Only a few lingering showers remain across south-central PA at the time of this writing. The aforementioned upper-level low is currently located over PA and western NY, and it will FINALLY be absorbed by the Jet Stream and drawn into New England tomorrow (see below). On its southern flank, a few more showers will dampen the Lower Susquehanna Valley overnight, but additional rainfall amounts should not exceed 0.10". Needless to say, the rain has been largely beneficial and a welcome sight for farmers and those with agricultural interests. A couple of minor tornadoes and localized incidents of wind damage and flash flooding have been the only prices to pay. In the wake of the upper low, west-to-northwesterly winds of 7-14 mph will usher drier and less humid air into the Commonwealth on Wednesday. Any lingering showers should diminish and push east of the I-95 corridor by daybreak, and skies will then turn out partly sunny with highs in the low-to-mid 70s and dewpoints in the low 50s. Unfortunately, the reprieve from the unsettled weather will likely be short-lived. After a mainly clear and comfortable Wednesday night with lows around or just above 50°F, another disturbance dropping southeastward from the Great Lakes region will trigger more scattered showers Thursday afternoon. Most of the day will be dry with light winds and increasing clouds accompanying highs in the low-to-mid 70s, but outdoor activities after work or school could be ruined and the PM commute slowed by convective showers and maybe even an embedded thunderstorm or two. The evolution of the disturbance from Thursday night through Saturday morning is highly uncertain, but it may also briefly detach, or close off, from the Jet Stream. If, where, and to what extent this occurs will determine the outcome of the forecast during this time period. A faster detachment and more amplified system could result in periods of steady rain, as well as cloudy, breezy and unseasonably cool conditions, from Thursday night through Friday night. A slower detachment and less amplified system would mean much less rain (isolated-to-scattered showers) during the period, along with partial sunshine and highs in the mid-to-upper 60s on Friday. Follow @MUweather on Twitter(X) for updates on the late-week forecast.. one tomorrow, and one on Thursday.. Fortunately, confidence in the forecast actually increases over Mother's Day Weekend. Regardless of the outcome late this week, the disturbance should get absorbed back into the main branch of the Jet Stream relatively quickly and lift into northern New England or Atlantic Canada by Saturday. Behind it, northwesterly winds of 10-20 mph will usher another drier and less humid air mass into the Northeast. A sprawling high pressure system over southern Canada on Saturday will settle into the eastern Great Lakes region by Mother's Day and shift into the western Atlantic early next week. The large- scale subsidence, or sinking motion, associated with the high will result in mostly sunny, dry and absolutely beautiful conditions over the holiday weekend! The weather should be nothing short of spectacular on Saturday for commencement activities at universities across the Commonwealth.. including the 171st Commencement Ceremonies at Millersville University. High temperatures will be in the upper 60s to low 70s following early-morning temperatures in the upper 40s to low 50s. Factor in plenty of sunshine, a refreshing breeze and ~45°F dewpoints, and conditions will be great for pre- or post-graduation pictures with family and friends! The weather on Mother's Day will be virtually identical to and equally as gorgeous as on Saturday. High temperatures may be a few degrees higher than Saturday but won't exceed the low-to-mid 70s Sunday afternoon (see below). Thus, it's "all systems go" for outdoor activities with Mom on Sunday! You'll be able to sleep with the windows open all weekend long without having to worry about rain, as well. Lows will be in the comfortable upper 40s to low 50s again both Saturday and Sunday nights, and dewpoints shouldn't climb back into the 50s until Monday afternoon or night. Skies should remain partly-to-mostly sunny on Monday with highs in the comfortable 70s for the 3rd-straight day. Quite frankly, it's almost impossible to dial up a nicer stretch of weather over a holiday weekend. Enjoy it! The threat for showers and thunderstorms won't return until the middle of next week. I'll have more on that this Friday.. -- Elliott