textproduct: State College

WHAT HAS CHANGED

* Going forecast very much on track * Keeping a close eye on NBM guidance max temps (may be too warm) for next week

KEY MESSAGES

1) Patchy --SHRA continue over the W early tonight and over the N/NE longer into the night

2) Significant summerlike temperature surge ramps through early next week; highest temperatures of the year so far

DISCUSSION

KEY MESSAGE 1: Patchy --SHRA continue over the W early tonight and over the N/NE longer into the night

18Z radar looks pretty wet with a stripe of -RA sliding through under the base of the upper low/trough. Drying is seen upstream, but the cyclonic circulation aloft will keep sct -SHRA long into the night over the NErn towns. The clouds over the SouthCentral-SErn towns should develop bigger breaks in them, but the W and esp the NE will stay pretty cloudy through mid- morning Fri. Mins tonight will be close to normal with the wind and clouds keeping us from getting too cold (40s, mainly).

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KEY MESSAGE 2: Significant summerlike temperature surge ramps through early next week; highest temperatures of the year so far

After a cool start to May, a significant summerlike warmup is on the horizon for this weekend through early next week. This large scale pattern shift should deliver a rather sudden warm surge with max temps projected to reach well into the 80s and even lower 90s. Daily record highs may be challenged based on the current fcst Monday and Tuesday. Max temps were adjusted lower by a few degrees due to a known systematic bias correction issue identified in the NBM during the shoulder seasons.

There may be some potential heat risk considerations looming for early next week, mainly for Monday and Tuesday. This stems not only with the forecast high temperatures and increased humidity, but also from an acclimation perspective. The summer like heat isn't expected to last long with the next frontal system expected mid to late next week, bringing cooler temps and precip.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Stratus with minimal breaks covers the CWA. However, there is set of diurnal cumulus under a higher deck in the SE third of the CWA. MDT & LNS should (80%) hang out in VFR for much of the night, dipping into MVFR cig for a few hours at most. There is a better chance for prolonged MVFR cig and --SHRA for IPT. But, they have just a 10% chc of going into IFR. The wrn sites (BFD and JST) will get socked in with IFR cigs for much of the night. BFD is getting an early start and JST may follow shortly as --RA is almost to the terminal at 1730Z. Expect UNV and AOO to be in the middle, literally, with the expectation (80%) that they will stay above IFR, but may still have some --SHRA pass thru, esp before 05Z. The SHRA slide east as the deep upper low/trough slides east. The majority of terminals will go VFR for the daytime, but may take until late morning to do so. The W wind will remain 8-12KT (or better) sustained with gusts into the upper teens and 20s, but will veer a little to the NW overnight.

VFR will rule for the rest of Friday with a slowing wind speed as the gradient starts to relax (from W-E thru the day). Calm air and a mainly clear sky is in store for Fri night as a high pressure ridge moves overhead (centered more to our S).

Outlook...

Sat-Sat Night...VFR is likely much of the time, although brief restrictions are expected at BFD and less likely at JST/UNV/AOO/IPT due to isold/sct SHRA/TSRA.

Sun...Sct SHRA/TSRA NW, VFR elsewhere.

Mon...Low cigs/isold --SHRA poss, mainly S.

Tue...Sct SHRA W. Otherwise, no sig wx.

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.