textproduct: State College

WHAT HAS CHANGED

* Severe thunderstorms have moved off to the east. Watch cancelled.

KEY MESSAGES

1) Storms have moved east and left us in the stable air for the night.

2) Chances of showers and storms become more widespread on Sunday and Monday, bringing both severe and flooding concerns for the end of the weekend and into the first of next week.

DISCUSSION

KEY MESSAGE 1: Storms have moved east and left us in the stable air for the night.

Severe storms have moved to the east of the CWA, leaving quite a bit of damage. The stable air overnight will help diminish the showers out there now (10 PM). The wind will become light, and fog is a good bet over most of the area due to the moisture in and just above the ground from rain earlier. A fog advisory may be necessary as the night goes on. Temps are already extremely different/lower than just a couple of hours ago.

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KEY MESSAGE 2: Chances of showers and storms become more widespread on Sunday and Monday, bringing both severe and flooding concerns for the end of the weekend and into the first of next week.

Recent HREF ensemble guidance and hi-res model guidance indicate some precipitation around the area late Sunday morning into the early afternoon hours before a general increase across the board on shower/thunderstorm coverage. The air mass across central Pennsylvania will be fairly moist, with HREF guidance indicating PWATs approaching in the 1.50-1.75" range across N/W PA with some locations in SE PA approaching 1.75-2.00" PWATs by the afternoon and evening hours. For reference to climatology if this solution pans out, this would be in the 90th to 95th percentile for PWATs for the beginning of July. Recent NBM QPF forecast brings 1.50-2.00" of rainfall into portions of SE PA on Sunday, with heaviest rain expected in the afternoon and evening hours with some heavier rain considering overnight into Monday morning. This heavy rain signal is matched in recent HREF ensemble guidance, with 24 hour LPMMs outlining some spot amounts between 3-4" for this same timeframe. This signal for heavy rain will bring some flooding concerns to the more urbanized corridors of SE PA, which is matched in the Slight Risk for Excessive Rainfall from WPC. The main thing that would preclude flooding concerns would be the fact that this area is in Severe (D2) Drought based on the most recent Drought Monitor; however, heavy rain will still very well cause instances of flash flooding. This heavy rain signal will be in place on Monday; however, slightly less rainfall forecast on Monday and will have to see what rainfall this evening though Sunday brings to the region before reading too much into this threat. There also will be some severe threat stationed across southern Pennsylvania, mainly south of the I-80 corridor with damaging winds being the main concern given ample instability in place.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

Any remaining showers will continue to dissipate through about 09Z, giving way to dry conditions for the rest of the night. Fog and low clouds are forming over northwest PA, likely bringing LIFR conditions to BFD for the rest of the night. There is some uncertainty regarding how widespread the fog gets, but UNV and IPT appear to have a greater than 50 percent chance of seeing IFR conditions at some point prior to sunrise. Chances are lower at the other TAF sites. The fog will dissipate by 15Z, giving way to VFR conditions for the rest of the morning.

Showers and thunderstorms will develop during the afternoon and are once again likely to impact all TAF sites through the evening. PROB30s have been included to highlight this potential, though the timing will need to be adjusted as confidence begins to increase. Storms will be capable of producing strong wind gusts, intense rainfall rates, and frequent lightning. Any storms that move directly over an airfield will likely lead to brief periods of IFR conditions.

Rain comes to an end from west to east after 00Z, though showers and storms may linger at MDT and LNS past 06Z. Fog and low clouds appear likely behind these showers and widespread IFR conditions will be possible into Monday morning.

Outlook...

Mon-Tue...Restrictions possible in A.M. fog and P.M. T-storms. Wed-Thu...Improving conditions expected.

CTP WATCHES/WARNINGS/ADVISORIES

None.