Sunrise 6:22 AM   Sunset 8:11 PM Moonrise 10:27 PM   Moonset 6:35 AM

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FXUS61 KPBZ 260500 AFDPBZ

Area Forecast Discussion National Weather Service Pittsburgh PA 100 AM EDT Fri Apr 26 2024

SYNOPSIS
Dry and warmer today. The risk for showers returns late tonight and Saturday. Big warmup expected Sunday and Monday.

NEAR TERM /THROUGH TODAY/
KEY MESSAGES:

- Dry and warmer today

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Overnight period in good shape. No major changes needed.

Upper level height rises today as an amplified ridge axis moves across the Upper Midwest. Surface high pressure will drift across the New England States this morning. Low-level flow on the backside the high may push some moisture back over the region this morning. Seeing some differences in the possible cloud cover from this moisture. The NBM keeps the highest probabilities of total cloud cover bottled up on the eastern side of the ridges, showing around 10% prob for >50% cloud cover west of the ridges. HRRR is more bullish with cloud cover particularly later this morning and into the afternoon.
Indicating around 60% prob of >50% cloud cover. Will lean toward the NBM solution as it did a good job with yesterday's persistent cloud cover.

Increased warm air advection will nudge highs back above normal today.

SHORT TERM /TONIGHT THROUGH SUNDAY/
KEY MESSAGES:

- Showers late tonight and Saturday with a warm front - Warmer Sunday with an isolated shower/storm possible in the afternoon

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Upper level ridge axis will slowly move through Ohio tonight and then across the rest of the forecast area on Saturday. A surface warm front will trail just behind the axis and push northward through the region late tonight and Saturday morning. Showers will accompany the passing boundary. Rainfall looks to be light with NBM probs of >0.1 inches around 30 to 40% tonight and 20 to 30% Saturday morning. The highest probs are generally over the I-80 corridor through the period. Showers should end late Saturday morning or early afternoon as the front will move well north of the region. Thunderstorm chances appear minimal as forecast soundings show little to no instability and a strong low level inversion. Warm air advection is anticipated behind the boundary, so temperatures will continue to moderate on Saturday. A limiting factor for highs on Saturday will be cloud cover behind the front associated with a shortwave trough that will push the morning ridge east of the area.

Strong height rises return Saturday night and an impressive ridge will take hold over the region on Sunday. A weak shortwave will try and sneak over top of the ridge bringing a small increase in shower/storm chances Sunday afternoon. The area with the highest probs for measurable precipitation will be north of Pittsburgh where 30 to 40% probs for >0.01 inches rest. With such a strong ridge, and forecast soundings showing a cap, it should be difficult for much activity to develop.

Warm air advection will continue on Sunday and temperatures will rise into the 80s across much of the district.

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
KEY MESSAGES:

- Warm with minimal chances of afternoon thunderstorms Monday.
- More widespread showers and possible thunderstorms with a Tuesday cold front.
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Model ensembles continue to indicate a strong ridge Monday.
The ridge axis is expected to shift slowly eastward later in the day, with slightly better chances for afternoon showers and thunderstorms as a shortwave trough, and associated surface cold front, begin to approach from the Midwest.

Temperatures mainly in the 80-85 degree range (outside of the higher terrain) are expected Monday.

Showers are likely, along with a few thunderstorms, on Tuesday as the trough and cold front cross the region. The precipitation should end Tuesday night as the front exits.

By Wednesday, one thing is more certain; the ridge amplitude will decrease. Clustered variability of the 500mb pattern sits anywhere between a weak 500mb trough to a weak 500mb ridge. This ridge breakdown may lean towards more unsettled weather.

Late next week, a central CONUS ridge may develop (shown in 3 out of 4 clusters). Should it develop, it is favored to move east (as shown in 2 out of 3 clusters) and allow warmer-than- normal temperatures to continue through next weekend. Some alternate scenarios include 1) the ridge not developing, whereby temperature would remain closer to normal in zonal flow and 2) the ridge develops but does not move east and enforces eastern troughing, which would keep temperatures below normal.

AVIATION /06Z FRIDAY THROUGH TUESDAY/
VFR is expected through this evening as the center of surface high pressure moves east of the region. CU rule and model soundings indicate scattered diurnal CU developing after sunrise, as convective temperatures are reached. These should dissipate by evening, though mid level cloud cigs will be increasing ahead of an approaching warm front. A few showers are expected toward the end of the 30 hr TAF period at PIT, though VFR should continue.

Wind will veer overnight from N to ESE by morning. Speeds will increase after sunrise, with some downsloping gusts around 20kt at LBE and DUJ.

Outlook
Showers and restrictions are likely on Saturday with the passage of the warm front. The highest SREF probabilities of persistent MVFR are currently north of PIT. VFR is then expected Saturday night through Monday as a ridge builds across the region, though an isolated afternoon thunderstorm is possible Sunday mainly north of PIT.

More widespread restrictions in showers and thunderstorms are expected with a Tuesday cold front.

PBZ WATCHES/WARNINGS/ADVISORIES
PA...Frost Advisory until 9 AM EDT this morning for PAZ007-013-014- 020-022-077-078.
Freeze Warning until 9 AM EDT this morning for PAZ008-009-015- 016.
OH...Frost Advisory until 9 AM EDT this morning for OHZ039>041- 048>050-057>059-068-069.
WV...Frost Advisory until 9 AM EDT this morning for WVZ001.

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