textproduct: Pittsburgh

SYNOPSIS

High pressure will result in quiet weather with lower humidity through Thursday. More widespread rain chances return later on Friday and into the weekend.

NEAR TERM /THROUGH TONIGHT/

KEY MESSAGES:

- Mostly clear with some river valley fog S of PGH this morning - Dry and pleasant weather today. ---------------------------------------------------------------

A mostly cloud-free night is underway as high pressure builds over the Ohio Valley. This has allowed valley fog (already present on satellite) to develop across the Morgantown region and into the WV ridges, where earlier rainfall has maintained a low-level moisture pool. Otherwise, a quiet night is in store. Morning low temperatures will fall into the low/mid 50s, which is near the climatologic average.

Dry weather and low humidity is expected today with high pressure. Low-level winds will back more southwesterly, increasing warm advection and boosting afternoon temperatures into the lower 80s under mostly sunny skies. HRRR and RAP smoke models do show an increase in upper level smoke this morning, but this is not expected to have much surface impact at this time.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/

KEY MESSAGES:

- Dry with warming trend through Thursday night. - Rain chance returns Friday. ----------------------------------------------------------------

High pressure will again keep dry weather in the forecast for Thursday, before drifting into the Mid-Atlantic. Increasing moisture advection will nudge dewpoints upwards into the low/mid 60s -- not quite "sticky" territory, but not as pleasant as today. With rising temperatures, heat index values with near 90F in the PGH urban corridor (60-70%) and Ohio River valley near HLG (70-80%).

Continued moisture advection will increase clouds late Thursday into Friday as a weak frontal boundary sets up somewhere west- east across the area. This will allow for moisture pooling and eventual destabilization with diurnal heating on Friday. Zonal flow aloft will be weak, likely supporting only weakly-organized convection Friday with low severe potential. However, PWATs look to approach the daily max for PIT. With little flow and high PWATs, slow-moving and locally heavy pulse to multicellular storms are likely.

Moist and cloudy conditions will keep overnight lows about 10 degrees above average Friday night.

LONG TERM /SATURDAY THROUGH TUESDAY/

KEY MESSAGES:

- Rain chances continue through the weekend and into next week. - Heavy rain and localized flash flooding is possible - Severe threat remains relatively low -------------------------------------------------------------------

An active rainy period continued through the long term as a stalled frontal boundary remains quasi-stationary across the region. PWATs remain very high on Saturday as slow-moving and weakly-forced diurnal storms develop once again. Given antecedent rainfall from the previous day, localized flash flooding potential will increase on Saturday for much of the area. WPC has us outlooked in a Day 4 Marginal Risk for excessive rainfall (Saturday into Sunday).

Unfortunately, little change is expected through Tuesday as the boundary slowly meanders across the region. Briefly-enhanced upper support with a crossing shortwave may further enhance rainfall rates Sunday into Monday. Pittsburgh and areas south are included in a Day 5 Marginal Risk for excessive rainfall (Sun into Mon). Rain chances are likely to continue Tuesday into Wednesday as another series of shortwaves crosses the region.

Temperatures are expected to cool slightly through the weekend before gradually warming into next week. However, daily highs are likely to remain near to just above normal.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

High pressure dominates the 12Z TAF cycle, maintaining VFR conditions with only some passing cirrus and upper-level smoke expected. West-southwest winds will be light during nighttime and early morning hours, increasing to around 7 to 10 knots with gusts to 15 knots during afternoon hours.

Outlook... High pressure and weak flow aloft is favored to maintain VFR and dry weather through Thursday. Weak disturbances within the upper flow may bring increased chances for precipitation and associated restrictions Friday afternoon into the weekend.

PBZ WATCHES/WARNINGS/ADVISORIES

PA...None. OH...None. WV...None.