textproduct: State College

WHAT HAS CHANGED

No significant changes other than focusing the greatest probs for showers/TSRA Monday afternoon through Tuesday.

KEY MESSAGES

1) Pleasant/dry pattern with comfortably low daytime humidity continues into the last weekend of July.

2) Turning more humid with several rounds showers and thunderstorms next week. Perhaps a few strong storms with heavy rain at times.

DISCUSSION

KEY MESSAGE 1: Pleasant/dry pattern with comfortably low daytime humidity continues into the last weekend of July.

Surface high pressure extending from the Lower Great Lakes to the New England states will bring another several days of very pleasant Mid Summer conditions with abundant sunshine today and a mix of sun and clouds for Saturday and Sunday.

While there could be one or two highly isolated showers or a thunderstorm over the region late this weekend (mainly over western portions of the state), the airmass remains quite dry.

High temperatures today and Saturday will range from the mid to upper 70s across the higher terrain, to the low 80s in the Central and Southern Valleys.

KEY MESSAGE 2: Turning more humid with several rounds of showers and thunderstorms next week. Perhaps a few strong storms late Monday and Tuesday afternoon/evening.

Highly diffluent northwesterly flow accentuated by a few shortwaves dropping southeast across the Great Lakes region will lead to an increasing probability for showers and thunderstorms. The highest chance for convection will come Monday afternoon and evening and again on Tuesday as a fairly compact, but potent mid and upper level short wave digs SE and amplifies significantly as it reaches our longitude.

The initial round of SHRA/TSRA will track SE along a slow-moving warm front and could be on the strong to severe side late Monday/Mon evening across parts of Central and Western PA

WPC has a broad level 1/4 marginal excessive rain risk for D5/Monday July 27 that covers most of CPA.

Sfc low tracking from Lake Superior on Monday and deepening by about 6 mb (to around 995 MB) by the time it reaches Lake Ontario at 18Z Tuesday will help to focus TSRA in PA during the day Tuesday along, and ahead of a surface cold front (that will be over NW PA late Tuesday morning with a well-defined lee trough extending down the Susq and Delaware Valleys Tues afternoon/early evening).

AVIATION /09Z FRIDAY THROUGH TUESDAY/

Valley fog formation has largely stayed out of BFD this morning with widespread VFR conditions as of 09Z Friday. There still will remain some potential for MVFR-to-IFR visibilities through 11Z Friday before chances rapidly decrease. In terms of the 12Z TAF package, widespread VFR conditions are virtually certain (over 90% confidence) at all airfields with light winds throughout the day. The main concern in terms of the 12Z TAF package will be the potential for clearing and calm winds between 06Z-12Z Saturday that will bring some potential for valley fog potential across the northern tier terminals with highest potential at BFD after 09Z Saturday. Confidence remains too low to include in the 12Z TAF package based on a persistence forecast but will need to continue to monitor this potential in future TAF packages.

Outlook...

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

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

Mon-Tue...Restrictions possible in showers/storms.

CLIMATE

Multiple record low temperatures were set for July 23rd across central Pennsylvania:

* Altoona set a record low temperature of 47 degrees was set, breaking the previous record of 50 degrees set back in 1981.

* Bradford tied a record low temperature of 38 degrees which was previously set in 1981.

* Johnstown tied a record low temperature of 49 degrees which was previously set in 1983.

CTP WATCHES/WARNINGS/ADVISORIES

None.