Sunrise 6:02 AM   Sunset 8:30 PM Moonrise 10:50 AM   Moonset 1:07 AM

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FXUS61 KPBZ 140745 AFDPBZ

Area Forecast Discussion National Weather Service Pittsburgh PA 345 AM EDT Tue May 14 2024

SYNOPSIS
Showers and a few thunderstorms will be possible today and Wednesday and again Friday through the weekend as multiple disturbances cross the region. Temperatures will remain slightly above normal.

NEAR TERM /UNTIL 6 PM THIS EVENING/
KEY MESSAGES:

- Shower/thunderstorm chances return today.
- No severe threat.
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Decreasing heights and increased moisture advection ahead of an approaching trough will support isolated to scattered light shower activity today, overspreading the area from the southwest this morning. Minimal shear and instability precludes any severe activity.

SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/
KEY MESSAGES:

- Shower/thunderstorm chances continue through Wednesday.
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As the mentioned upper trough over the Midwest tracks eastward across the Ohio Valley into Wednesday and eventually sliding east of the area by Wednesday night, increasing moisture and ascent will result in a greater coverage of showers and thunderstorms across the entire area through that time, with activity tapering off Wednesday night as an upper ridge begins to build in from the west in the wake of the trough. Rainfall amounts are expected to remain generally light through this system, with widespread amounts forecast to remain in the 0.25-0.75 inch range. Ensemble probabilities of storm total QPF greater than 0.5" is roughly 60-70% south of I-70 and 40-50% farther north. In fact, probabilities for an inch of rain in this 48 hour window are near or less than 30% everywhere. That said, while widespread rainfall amounts will be generally light, locally higher amounts will remain possible if any locations see multiple rounds of thunderstorms during this period, since the heaviest rates can be expected in any storms. The severe weather threat remains low as both instability and bulk shear will be marginal at best during this period.

LONG TERM /THURSDAY THROUGH MONDAY/
KEY MESSAGES:

- Dry conditions briefly return Thursday.
- Ensemble spread is still relatively high, but another trough appears to bring showers and thunderstorms back to the forecast late Thursday through the end of the week.
- Above normal temperatures continue.
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A weak upper ridge quickly builds into the area in the wake of the departing trough, bringing a brief period of dry weather early on Thursday. However, another upstream trough will be hot on its heels, digging into the Great Lakes region and quickly ushering the upper ridge off to the east. This will bring increasing chances for showers and storms back to the area Thursday afternoon through the end of the week.

AVIATION /08Z TUESDAY THROUGH SATURDAY/
Cigs will lower to low VFR/isolated MVFR this morning as a shortwave trough, embedded in SW flow ahead of a parent trough across the Midwest, approaches and crosses the region producing showers. The showers should become scattered again this afternoon as the initial wave exits to the northeast.

Some destabilization is expected by late afternoon into early evening, with HRRR MU CAPE near 500 j/kg south of a line from PHD-BVI-LBE. This could result in a few thunderstorms developing, as another vorticity maximum begins to approach the region. Maintained the prob30 mention for this potential.

Low VFR cigs and scattered showers are expected tonight as the next wave rotates around the main trough. Patchy MVFR cigs are possible, mainly SE-NE of PIT where more favorable low level moisture is progged.

Outlook
Restrictions are likely, along with showers and possible thunderstorms, Wednesday as slow moving low pressure crosses the region. A brief return to VFR is possible Thursday as ridging briefly builds in. Restrictions and showers return Friday and Saturday with another slow moving low pressure system.

PBZ WATCHES/WARNINGS/ADVISORIES
PA...None.
OH...None.
WV...None.

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