textproduct: State College

WHAT HAS CHANGED

* Western edge of the showers pushing east of our area. * Nudged high temperatures down Sunday-Tuesday to account for known biases in the NBM forecast in patterns like this.

KEY MESSAGES

1) Showers with gusty winds have ended.

2) Hottest temperatures of the year so far forecast early next week with highs pushing into the 80s and 90s.

3) Strong cold front to bring showers and storms with potential for severe weather on Wednesday followed by colder temperatures.

DISCUSSION

KEY MESSAGE 1: Showers with gusty winds have ended.

The combination of fast moving showers and dry air at low levels resulted in some gusty winds earlier but they showers have moved out of most of the area as of mid evening.

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KEY MESSAGE 2: Hottest temperatures of the year so far forecast early next week with highs pushing into the 80s and 90s.

Daytime high temperatures will be steadily rising today through early in the upcoming week. An anomalous upper ridge building over the east-central U.S. will deliver summerlike conditions this weekend through the first part of the new week. High temperatures will peak in the mid 80s to lower 90s Monday and Tuesday and could challenge daily records in some locations.

Manual adjustments were made to lower NBM maxT by a few degrees due to a known systematic bias correction issue identified during the shoulder seasons. This should also keep max heat indices under 100F for the most part. However, heat risk impacts will continue to be monitored given the quick ramp- up in heat and limited acclimation time. Dewpoints over 60s for many will also feel quite humid relative the recent cool stretch we've had.

With a boundary just to our north and sufficient instability in the warm sector over PA, there will be a chance for some stray afternoon and early evening showers or thunderstorms Monday and Tuesday. Most folks should stay dry, but thunderstorms could drop a quick 0.10 to 0.25" of rain in any one location.

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KEY MESSAGE 3: Strong cold front to bring showers and storms with potential for severe weather on Wednesday followed by colder temperatures.

A cold front (accompanied by more widespread and frequent showers/t-storms) brings relief next Wednesday into Thursday. Some of the AI guidance paints an elevated risk of severe weather across the Lower Susquehanna Valley on Wednesday afternoon in the presence of peak heating and sufficient shear/CAPE profiles. The magnitude & location of the severe threat will be highly dependent on cold front passage timing. The eventual risk area will highlight locations along and downstream of the cold front between 12PM and 8PM on Wednesday.

In the wake of the cold front, high pressure will build in for a short time. Temperatures are forecast to cool down back to historical/climo averages for late May for the end of next week. Early indications show the aforementioned cold front stalling out south of the Mason-Dixon line late in the week and lifting back north across PA as a warm front into Memorial Day weekend. The current outlook favors a cooler/wetter stretch through the holiday weekend thanks to that warm front, but there is still a lot of time for the forecast to trend in a more favorable/optimistic direction for the holiday weekend that marks the unofficial start of summer.

AVIATION /01Z SUNDAY THROUGH THURSDAY/

Currently, weakening scattered showers are making their way across Central PA. These have the potential for some light showery activity at IPT, MDT, and LNS as well as slightly windier conditions as they pass by. Some lowering of ceilings of is possible but VFR expected to prevail through the night, although IPT may see a few hours of MVFR/low end VFR. Drier conditions at the surface and a stabilizing environment make rain impacting the surface less likely but worth mentioning as a possibility.

Uncertainty remains present in extent of fog development for western terminals (BFD and JST). BFD looks more likely to see visibility drops, especially if any showers develop overnight.

Generally conditions improve to VFR region wide by noon with BFD, JST, and UNV most likely to hold onto MVFR restrictions during the morning. The afternoon will see higher cloud bases closer to 10kft.

Outlook...

Mon-Tue...Mainly VFR. Patchy A.M. fog. Isolated P.M. shower or t-storm possible.

Wed...Restrictions probable through Wednesday night with widespread showers/storms along CFROPA.

Thu...Lingering showers across S PA, restrictions possible.

CLIMATE

Daily record max temperature for May 18-19:

5/18 5/19 Harrisburg 94 in 1962 95 in 1962 Williamsport 95 in 1962 96 in 1996 Altoona 91 in 1962/1996/2017 92 in 1996 Bradford 85 in 1962 85 in 1962 State College 92 in 1962 92 in 1934/1996

Please note: State College Co-operative observations are a 24-hour summary taken once per day around 7 AM (7AM-7AM). Therefore, a max temp occurring in the daylight or late in the day is usually reported in the _next_ day's observation. Also, the same min temp may be reported on two consecutive days if the min occurs at observation time.

CTP WATCHES/WARNINGS/ADVISORIES

None.