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FXUS61 KPBZ 010532 AFDPBZ

Area Forecast Discussion National Weather Service Pittsburgh PA 132 AM EDT Sat Jun 1 2024

SYNOPSIS
Dry weather continues through the daytime on Saturday with warming temperatures. Rain will return to the area Saturday night and Sunday with crossing low pressure. Above normal temperature and low probability showers and thunderstorms are favored thereafter until the next system arrives mid to late week.

NEAR TERM /THROUGH TODAY/
KEY MESSAGES:

- Dry weather continues through Saturday.
- Temperatures will warm back above-normal on Saturday.
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Update...
The latest surface analysis shows high pressure centered across the western PA. An upper ridge was also building in from the Midwest, with 1000-500mb height rises of 60 meters across OH, PA and northern WV. The 00Z PIT sounding shows dry air through the column, which will help to maintain mainly clear skies and dry weather overnight. Radiational cooling is expected again tonight, though it will not likely be as efficient as last night with weak warm advection aloft. Still, readings should drop into the lower to mid 40s for most locations, with some upper 30s possible in the usually colder locations.

Previous discussion...
Cloud cover will increase on Saturday as the trough crosses from the Mississippi Valley into the Ohio Valley by late day. Warm advection will boost afternoon temperatures back to just above average, yielding area highs in the upper 70s to lower 80s.

SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/
KEY MESSAGES:

- Showers and low probability thunderstorms arrive late Saturday through Sunday.

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The shortwave trough will near the area late Saturday, crossing on Sunday. Generally light rain showers are expected with this system Saturday night through Sunday. Probability for thunder will be low as even 75th percentile SBCAPE values don't exceed 100 J/kg, though the highest chance for any rumbles will be Sunday afternoon. Showers will continue through the day until the wave exits, becoming more scattered/isolated in the afternoon. Lingering showers should gradually wane through the evening and overnight. Flooding/severe threats should remain minimal due to weak instability and weak deep-layer shear.

Cloud cover and ongoing showers will limit diurnal heating, keeping Sunday afternoon highs ten or so degrees cooler than Saturday.

LONG TERM /MONDAY THROUGH FRIDAY/
KEY MESSAGES:

- Low probability showers and thunderstorms with above normal temperature likely to start the next work week.
- More widespread precipitation favored with mid to late week low pressure system.
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Ensembles generally favor gradual ridge building across the Tennessee and Upper Ohio River Valleys Monday into Tuesday with some shortwave movement to the north as troughing develops over the northern Rockies. This should promote above normal temperature and mainly dry weather for Monday as subsidence and weak flow keep diurnally driven convection very isolated (perhaps a thunderstorm or two in the ridges). The deviation for that forecast could come Tuesday if shortwave movement is more robust/deeper to the north Tuesday, which would increase convective potential during the day (favored ECMWF route).
Either scenario would still be somewhat dependent on storm evolution well west of the region and its impact on the larger scale flow.

The synoptic pattern shows greater variation mid-week as not all model solutions track the northern Rockies trough toward the Great Lakes. Current model consensus, and this forecast package, does trend toward the approaching/passing trough scenario which would promote more widespread showers/thunderstorms during the mid to late week period. If ridging proves to be more stout ahead of the troughs approach, that could delay the uptick in precipitation chances till next weekend while maintaining a more dry and seasonable warm pattern. Nonetheless, the variations remain too wide for any discussion of severe or flooding threats at this time.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
VFR will continue as high pressure moves east across the Upper Ohio Valley region. Light and variable wind tonight will veer to the SSE later this morning with speeds around 5 kt.

Outlook
Restrictions and showers/possible thunderstorms return Sunday with a crossing trough of low pressure. Current ensemble guidance indicate a 60-70% chance of MVFR on Sunday. MVFR to IFR fog/stratus is possible Sunday night with low level moisture in place. VFR returns later Monday and Tuesday under high pressure, before a restriction and shower/thunderstorm potential returns with a Wednesday cold front.

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

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