textproduct: State College

WHAT HAS CHANGED

* Elk County added to Flood Watch * Greatest excessive rain and flash flooding risk shifted into western and southwestern Pennsylvania

KEY MESSAGES

1) Localized flash and urban flooding impacts are possible again this afternoon and evening

DISCUSSION

KEY MESSAGE 1: Localized flash and urban flooding impacts are possible again this afternoon and evening

Another round of heavy rain producing convection is anticipated this afternoon and evening. The setup remains supportive for heavy rain with waves of low pressure moving along a wavering stationary frontal zone and interacting with a favorable thermodynamic environment. Thunderstorms will be capable of highly efficient rainfall rates with repeat/training potential.

The greatest risk for flash flooding has shifted from the eastern into the west/southwest portion of the forecast area (based on the HREF and REFS model output) where FFGs are lower and terrain influences are more in-play. However, will opt to maintain current watch status to account for lingering convective uncertainty while adding Elk County per coordination with WFO PBZ. We also considered adding Warren County in coordination with WFO CLE, but decided to hold off for now. On balance, we are leaning/messaging a reduced FF threat for the eastern part of the watch area owing to lower instability and considerably less QPF response in the CAM guidance.

The severe storm threat also does not appear to be as robust as in prior days (54 SVR+TOR warnings in the past 3 days). This is reflected in most of the area in a general or non-severe TSTM outlook and only level 1/5 MRGL risk covering the southwest third of the CWA where higher CAPE and steeper lapse rates will be maximized.

The pattern for the rest of the week can be summarized more or less by typical early July unsettled/humid summertime conditions with a low probability of significant hazardous weather.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Patchy fog will gradually improve through the morning, but low clouds will stick around for much of the day with persistent easterly flow. MVFR or IFR ceilings are likely at most TAF sites, though JST and AOO likely see a period of VFR ceilings this afternoon.

Showers and thunderstorms will develop during the afternoon, but instability will be more limited than it has been the past few days. As a result, we will keep thunder mentions limited to BFD, JST, and AOO for now. Showers and thunderstorms will produce very heavy rainfall, leading to reduced visibility as they move over any airfields. Another night of low clouds and fog appears likely for Monday night behind these showers and storms. Outlook...

Tue...Restrictions possible in A.M. fog and P.M. T-storms. Wed- Fri...Restrictions possible in showers/storms, most widespread on Friday.

CTP WATCHES/WARNINGS/ADVISORIES

Flood Watch through this evening for PAZ010-017>019-024>028- 033>036-042-045-046-049>053-056>059-063>066.