269
FXUS61 KPBZ 291935
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
335 PM EDT THU MAY 29 2025
SYNOPSIS
LOW PRESSURE TRACKING ACROSS WEST VIRGINIA WILL BRING SHOWERS
AND POSSIBLY A THUNDERSTORM FRIDAY, ESPECIALLY FROM PITTSBURGH
SOUTHWARD. SHOWERS WILL LINGER INTO SATURDAY AS ANOTHER LOW
PRESSURE AREA DROPS OUT OF THE GREAT LAKES. COOL AND BLUSTERY
WEATHER IS EXPECTED SATURDAY AND READINGS WILL BE ABOUT 10
DEGREES BELOW NORMAL.
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
KEY MESSAGES:
- RAIN CHANCES INCREASE SLIGHTLY IN THE AFTERNOON/OVERNIGHT.
- TEMPERATURES AROUND NORMAL.
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A LOW LEVEL SHORTWAVE RIDING UP THE PREVAILING WESTERLY MID-
LEVEL FLOW WILL ALLOW SOME MEAGER FORCING FOR SHOWER AND
SCATTERED STORM DEVELOPMENT THIS AFTERNOON, THOUGH INTENSE
UPDRAFT DEVELOPMENT SEEMS VERY LOW PROBABILITY WITH AMPLE DRY
AIR IN THE 700MB TO 500MB LAYER AS EVIDENCED BY THE 12Z
SOUNDING. WHILE MOST RAIN WILL BE WARM RAIN, IT IS EXPECTED TO
BE QUITE SHALLOW AND BELOW THIS LAYER. HREF MAXIMUM RAINFALL
RATES ARE AROUND 0.25"/HR AND CONFINED TO ISOLATED, FAIRLY
PROGRESSIVE CELLS. THIS WILL CONTINUE A LOW FLOODING THREAT
LATER TODAY AND TONIGHT AS THIS WAVE MOVES THROUGH.
MID-LEVEL FLOW ACCELERATES OVERNIGHT AHEAD OF THE NEXT WAVE,
BUT THE BEST FORCING DOES NOT ARRIVE UNTIL AFTER SUNRISE. MOSTLY
BROKEN CLOUD DECKS WILL PREVAIL WITH TEMPERATURES RIGHT AROUND
SEASONAL NORMALS.
SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/
KEY MESSAGES:
- WIDESPREAD RAINFALL RETURNS FRIDAY ESPECIALLY PITTSBURGH ON
SOUTH
- THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN NORTHERN WV
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POSITIVELY TILTED TROUGH OVER THE GREAT LAKES WILL PIVOT AND
SWING TOWARD THE UPPER OHIO VALLEY ON FRIDAY. DURING THIS TIME
IT WILL PHASE WITH THE BROADER TROUGH DIGGING OUT OF CANADA,
DEEPENING AS IT CROSSES INTO PA AND SHIFTS TOWARD NEW ENGLAND.
WITH LEFT EXIT JET SUPPORT AND 700MB FRONTOGENESIS INTENSIFYING
FOR A PERIOD OVER NORTHERN WV/SOUTHWESTERN PA, THINK IT IS
REASONABLE TO SEE A PERIOD OF MODERATE RAINFALL, THOUGH PWATS
WON'T BE CLIMATOLOGICALLY HIGH OVER THE AREA. THAT BEING SAID,
PORTIONS OF NORTHERN WV DID RECEIVE 1.50-3.00" OVER THE LAST 48
HOURS, SO EVEN MODERATE RAINFALL ON SATURATED SOILS COULD POSE A
FLOOD CONCERN. WPC HAS EXPANDED THE SLIGHT RISK OF EXCESSIVE
RAINFALL TO ENCOMPASS THESE AREAS, WHICH SEEMS APPROPRIATE.
HREF PROBABILITIES OF >1.00" IN AN HOUR ARE SMALL (GENERALLY
UNDER 10%), BUT THERE IS A SIGNAL NONETHELESS. AT THIS TIME,
WILL OPT NOT TO HOIST A WATCH BUT WILL HIGHLIGHT THE CONCERN IN
THE HWO.
FARTHER NORTH, THERE IS STILL GOOD CONFIDENCE IN MEASURABLE
RAINFALL, PARTICULARLY FROM A LINE FROM ABOUT ZANESVILLE TO
PITTSBURGH, TO NEAR INDIANA. THERE, MEAN PRECIPITATION THROUGH
FRIDAY NIGHT RANGES FROM 0.25 TO 0.75".
THE LOW WILL MOVE OFF TO THE EAST FRIDAY NIGHT, AS A SECONDARY
WAVE DIVES SOUTHWARD INTO THE BASE OF THE TROUGH. SHOWERY
PRECIPITATION WILL LINGER INTO SATURDAY WITH THE OVERNIGHT COLD
FRONT PASSAGE AND AS COLD NORTHWEST FLOW ALLOWS FOR SOME LAKE
ENHANCEMENT. SUBSIDENCE WILL END PRECIPITATION BY LATE SATURDAY
BUT COLD 850HPA TEMPS NEAR 0-2C WILL KEEP TEMPERATURES BELOW
AVERAGE.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
KEY MESSAGES:
- WARMING TEMPERATURES BEGIN SUNDAY AND CONTINUE THROUGH MIDWEEK
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UPPER TROUGH WILL EVENTUALLY BE REPLACED WITH RIDGING AS WE GO
INTO NEXT WEEK. 500MB HEIGHTS WILL BE AROUND 580DAM+ BY TUESDAY
SUPPORTING A WARMING TREND THROUGH THE PERIOD. BY TUESDAY AND
WEDNESDAY, WE WILL LIKELY SEE TEMPERATURES ABOVE NORMAL. NBM
HAS THE PROBABILITY OF >80 DEGREES NEAR 60% OR ABOVE SAVE FOR
THE TERRAIN. BY WEDNESDAY THERE IS GREATER THAN 70% CHANCE OF
EXCEEDING 85 AREAWIDE.
SUBSIDENCE WILL MAINTAIN DRY CONDITIONS THROUGH THE LONG TERM.
AVIATION /20Z THURSDAY THROUGH TUESDAY/
FOR ANY SITES YET TO RETURN TO VFR EARLY THIS AFTERNOON, EXPECT
THAT THAT WILL OCCUR BY 18-19Z WITH STRATUS ERODING AND BECOMING
A DIURNALLY DRIVEN CU DECK WITH CLOUD BASES AROUND 5-6KFT.
OCCASIONAL GUSTS UP TO 20 KTS CAN'T BE RULED OUT THIS AFTERNOON,
BUT WIND IS LIKELY TO REMAIN BETWEEN 5-10 KNOTS OUT OF THE
SOUTHWEST BEFORE CALMING OVERNIGHT.
SOME AREAS OF FOG ARE AGAIN POSSIBLE TOWARD DAWN ON FRIDAY
MORNING WITH HIGHEST PROBABILITY AT MGW AND LBE WHERE WIND IS
EXPECTED TO BE LIGHTEST AND CROSSOVER TEMPERATURES ARE MORE
LIKELY TO BE ACHIEVED. CONFIDENCE IS LOWER AT OTHER SITES, BUT
IF OTHERS WERE TO BE AFFECTED, IT WOULD LIKELY BE AGC, HLG, AND
BVI. AT THIS POINT, OPTED NOT TO MENTION VIS RESTRICTIONS AT
THOSE THREE, BUT FURTHER CONSIDERATION MAY BE NEEDED FOR THE
NEXT UPDATE CYCLE.
WIND WILL PICK UP OUT OF THE WEST TO NORTHWEST TOMORROW MORNING
AS MID AND HIGH LEVEL CLOUDS THICKEN AND LOWER AHEAD OF
APPROACHING AFTERNOON RAIN CHANCES. TOP DOWN SATURATION WILL
NEED TO OCCUR BEFORE APPRECIABLE RAIN REACHES THE GROUND AND
RESTRICTIVE CIGS ARRIVE. PROBABILITY FOR RAIN IS HIGHEST FROM
PIT/AGC SOUTH AFTER 17Z OR SO. MVFR RESTRICTIONS ARE LIKELY
WITHIN THE SHOWERS WITH A 70-90% CHANCE, BUT ASIDE FROM
PIT/MGW/ZZV, IMPACTS ARE LIKELY TO BEGIN JUST OUTSIDE OF THE
CURRENT TAF PERIOD.
OUTLOOK...
TRANSITION TO NW FLOW WILL MAINTAIN PERIODS OF MVFR CLOUDS WITH
SHOWERS SATURDAY BEFORE HIGH PRESSURE AND DRY ADVECTION FAVOR
VFR SATURDAY NIGHT. THERE IS A HIGH PROBABILITY FOR A PROLONGED
PERIOD OF VFR AND DRY WEATHER SUNDAY INTO EARLY NEXT WEEK.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...34
NEAR TERM...MILCAREK
SHORT TERM...34
LONG TERM...34
AVIATION...MLB
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