textproduct: State College

WHAT HAS CHANGED

* Severe and flooding threat for this evening has largely decreased across all of central Pennsylvania. * Included the Marginal Risk for severe thunderstorms across SE PA tomorrow and outlook for the rest of the forecast period.

KEY MESSAGES

1) Severe and flash flooding threat has largely diminished this evening with no widespread hazardous weather expected tonight.

2) Outside of some strong-to-severe storms across Lancaster County on Wednesday, generally tranquil weather expected through the end of the work week.

DISCUSSION

KEY MESSAGE 1: Severe and flash flooding threat has largely diminished this evening with no widespread hazardous weather expected tonight.

Current radar outlines a cluster of showers with some isolated lightning strikes across northern Indiana County with scattered showers behind this cluster that will continue to move into Clearfield/Cambria counties over the next hour. Severe threat has largely waned given stability across the region despite the favorable shear parameters based on the most recent SPC Mesoanalysis parameters. Flooding threat also remains fairly low across the region with the only area of real concern given the overall lack of widespread heavy rainfall this afternoon and evening and a fall off of rainfall rates overall. Some potential for fog formation across the higher elevations of western Pennsylvania where heavy rainfall was observed today; however, the signal is not super strong at this time with overall dew point depressions still having a bit of ways to fall before fog formation occurs tonight. If fog forms across higher elevations, rapidly changing driving conditions could be present across portions of the Allegheny Front into Wednesday morning.

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KEY MESSAGE 2: Outside of some strong-to-severe storms across Lancaster County on Wednesday, generally tranquil weather expected through the end of the work week.

Surface cold front will continue to push eastward across central Pennsylvania tomorrow morning and throughout the afternoon hours, which will bring some potential for showers and storms to Lancaster County during the late afternoon hours depending on the speed of the cold frontal passage. More recent NBM guidance has trended back on precipitation mentions across the region and this is shown in the most recent forecast. If the cold front trends slower, it appears there would be enough moisture and potentially shear in place to bring a threat for marginally strong-to-severe thunderstorms. It is of note that instability will likely not be super sufficient for severe thunderstorms given morning cloud cover in place across the region, which could tamper the severe threat should the slower cold frontal passage solution play out in real time.

Dry conditions prevail Wednesday evening and are generally expected to continue through the Saturday evening based on most recent NBM model guidance. Towards the latter half of the weekend and into the beginning of next week, overall an unsettled pattern appears to take hold of the region with showers and chances of afternoon/evening thunderstorms progged by NBM model guidance. Despite this, no large-scale signals for severe weather at this time.

AVIATION /02Z WEDNESDAY THROUGH SUNDAY/

Current SHRA/TSRA stationed just west of BFD could continue to maintain itself over the next hour or two before running into a layer of more stable air and generally go onto a weakening trend. Current forecast outlines no TSRA mentions throughout the 00Z TAF package; however, VCTS could be possible at BFD through 01Z. The bulk of lightning activity is expected to be south of the airfield; however, so no mentions. SHRA mentions retained further east at UNV/IPT where this complex could sustain itself and bring lower ceilings/visibilities but generally not below IFR thresholds. Secondary complex of SHRA is expected at MDT/LNS brining SHRA and lower ceilings/visibilities with MVFR likely the worst-case scenario at this time.

Overnight, HREF/GLAMP guidance outlines lower ceilings and visibilities most likely across the western terminals (BFD/JST) so have continued to outline this potential in the updated forecast package. Elsewhere, guidance paints a more optimistic picture for flying conditions compared to the 18Z TAF package, likely due precipitation not being as widespread as originally forecast. Some pockets of MVFR/IFR will be possible at UNV/IPT as well; however, will mainly be based on precipitation reaching the airfield and a slight decrease in winds so this remains a lower confidence solution at this time. Gradual improvement of the western airfields is expected after sunrise, with widespread VFR conditions expected to prevail in the 14-16Z Wednesday timeframe with high (~70-80%) confidence. These conditions are likely (~80-90%) confidence to continue after prevailing through the end of the 00Z TAF package.

Outlook...

Thu-Fri...Some potential for valley fog across NW PA Friday morning; otherwise, VFR conditions expected.

Sat...Generally VFR conditions with low-end (< 20%) chance of an afternoon shower/storm across SW PA.

Sun...Increasing chances of PM showers/storms, with some restrictions possible.

CTP WATCHES/WARNINGS/ADVISORIES

None.