Sunrise 6:07 AM   Sunset 8:41 PM Moonrise 4:01 PM   Moonset 3:03 AM

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FXUS61 KPBZ 191343 AFDPBZ

Area Forecast Discussion National Weather Service Pittsburgh PA 943 AM EDT Sun May 19 2024

SYNOPSIS
High pressure will provide mainly dry weather and a warming trend in temperatures through Tuesday. Showers and storms return Wednesday through late week.

NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:

- Mostly sunny this afternoon. Isolated showers possible on the ridges.
- Above-normal temperatures continue as a warming trend begins.
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The remaining fog/stratus will mix out by 11 AM, leading to a mostly sunny sky CWA-wide under an upper ridge. Model cumulus rule favors the ridges/areas east of Pittsburgh for afternoon mainly scattered convective cloud development, and have shaded the grids in that direction. CAMs are still advertising isolated showers in the ridges, and this seems reasonable with expected elevation-aided convergence. Added a very small PoP to these areas. Afternoon high will climb into the low to mid 80s across much of the area this afternoon, around 10 degrees above normal for this time of year.

Mostly clear skies, light winds, and above-normal temperatures continue straight through tonight with lows expected to remain in the mid to upper 50s across the area.

SHORT TERM /MONDAY THROUGH MONDAY NIGHT/
KEY MESSAGES:

- Dry weather can be expected through Monday night.
- Temperatures continue to climb to 10-15 degrees above normal.
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Dry weather is still forecast for the majority of the region through Monday night as the upper ridge remains in place overhead. Temperatures continue to warm as well, reaching the mid to upper 80s during the afternoon, roughly 10-15 degrees above normal for this time of year. Lows Monday night remain in the 60s for most areas outside of the ridges, where mid to upper 50s remain likely.

LONG TERM /TUESDAY THROUGH SATURDAY/
KEY MESSAGES:

- Dry and quite warm Tuesday.
- Rain chances return for Wednesday and Thursday, with some potential for strong thunderstorms.
- Seasonable temperatures and lower rain chances are expected Friday and Saturday.
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Dry weather prevails through Tuesday night as the upper ridge slowly works its way off of the Atlantic Seaboard. A very weak shortwave moving through its northwest periphery traverses the lower Great Lakes Tuesday afternoon and could bring just enough lift to support a few isolated showers and storms across NW PA and NE OH. This is reflected in the forecast with low-end PoPs (~20%) primarily north of I-80 and across our northernmost tier of Ohio counties. The bigger impact on Tuesday will be temperatures, with plenty of sunshine and dry antecedent conditions pushing values further into the upper 80s and potentially closing in on 90 degrees in some areas. Ensemble probabilities for highs on Tuesday reaching 90+ degrees are >50% in river valleys and urban areas at this time. It's not out of the question for some of the "cooler" daily records (86 at DUJ, 91 at PHD, and 92 at PIT/MGW) to be within reach.

While models continue to show some minor differences with the strength and timing of a series of troughs ejecting from the central Rockies across the Plains during the middle part of the week, the larger overall signal generally favors a deepening upper low over the Upper Great Lakes Wednesday morning and a second shortwave trough subsequently rotating around its southern periphery and across the lower Great Lakes Wednesday night into Thursday. The result of this pattern is increasing chances for showers and thunderstorms both Wednesday and Thursday across the local area, with the highest probabilities (currently 50-70%) coincident with the latter shortwave timing Wednesday night and Thursday morning. We will continue to watch for the potential for severe weather with this system, as CIPS/CSU severe guidance continues to show some potential, particularly on Wednesday. Temperatures on Wednesday, while still expected to run above normal, may be knocked down a few degrees compared to Tuesday due to the increasing cloud cover and coverage in showers and storms.

Model divergence increases as we look beyond the cold front passage on Thursday, but it does appear that the passage of additional weak shortwaves may provide lower-end chances (20-40%) for rain straight through the weekend, with temperatures returning closer to climatology during that time.

AVIATION /14Z SUNDAY THROUGH THURSDAY/
Lingering IFR fog restrictions remain at a few sites (HLG, AGC, ZZV) this morning with river valley fog showing quite nicely on satellite imagery. FKL/DUJ have seen low level moisture manifest as stratus and are still stuck in LIFR to IFR CIGs .
Expect these restrictions to improve within the next couple hours and by 14z or shortly thereafter all sites will return to VFR and remain there with high confidence through today with mostly clear skies and light to calm winds under high pressure.

Patchy fog remains possible (40-60% chance) Sunday night once again, but mainly after 06Z and east of Pittsburgh.

Outlook
VFR and dry weather with high confidence are expected Monday and Tuesday under the influence of high pressure. Precipitation chances and associated restrictions return Wednesday with the passage of a cold front.

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

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