358
FXUS61 KPBZ 291615
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1215 PM EDT THU MAY 29 2025
SYNOPSIS
RELATIVELY QUIET WEATHER IS EXPECTED TODAY WITH READINGS WARMING
TO NEAR NORMAL. LOW PRESSURE TRACKING ACROSS WEST VIRGINIA WILL
BRING SHOWERS FRIDAY ESPECIALLY FROM PITTSBURGH AREA ON SOUTH.
SHOWERS WILL LINGER FRIDAY NIGHT AND 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 /THROUGH TONIGHT/
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 /FRIDAY THROUGH FRIDAY NIGHT/
KEY MESSAGES:
- WIDESPREAD RAINFALL RETURNS FRIDAY ESPECIALLY PITTSBURGH ON
SOUTH
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UPPER TROUGH DIVING SOUTH OUT OF ONTARIO WILL PHASE WITH OHIO
VALLEY TROUGH AND ALLOW IT TO DEEPEN AS IT HEADS EAST. THE
RESULT IS 90-120 METER HEIGHT FALLS ALONG THE MASON-DIXON LINE
ON FRIDAY.
LOW PRESSURE SHOULD DEEPEN AS IT MOVES ACROSS EASTERN KENTUCKY
AND WEST VIRGINIA IN THE MORNING AND HEADS FOR THE CHESAPEAKE
BAY IN THE EVENING. BY THE TIME THE LOW REACHES SOUTHERN NEW
ENGLAND LATE FRIDAY, IT WILL HAVE DROPPED ABOUT 20 MB IN 24
HOURS WHICH IS QUITE IMPRESSIVE FOR THE END OF MAY.
CONFIDENCE IN A SWATH OF RAIN PRODUCING 0.25-0.50" IS
RELATIVELY HIGH FROM ZANESVILLE TO PITTSBURGH TO INDIANA ON
SOUTH. DOWN IN PRESTON AND TUCKER COUNTIES WV, RAINFALL OF
0.50-1.00" IS LIKELY WITH NBM 90TH PERCENTILE PQPF24 PRODUCING
ABOUT 1.75". WPC HAS INTRODUCED A SLIGHT RISK OF EXCESSIVE RAIN
TO TUCKER COUNTY AS A RESULT, GIVEN THE RECENT 2.00-2.50" OF
RAINFALL.
DESPITE THE PRIMARY TROUGH PUSHING EAST TONIGHT AND ENDING UP
AROUND NEW YORK CITY, THE TROUGH DIGGING OUT OF ONTARIO INTO THE
GREAT LAKES SHOULD ARRIVE OVER FORECAST AREA LATE FRIDAY TONIGHT,
WITH HEIGHTS CONTINUING TO FALL ANOTHER 60 METERS TO NEAR 5500
AT 500 MB. THIS TROUGH SHOULD BRING ANOTHER ROUND OF SHOWERS
AFTER MIDNIGHT TO MOST OF THE FORECAST AREA.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
KEY MESSAGES:
- COOL AND BLUSTERY DAY ON SATURDAY WITH READINGS ABOUT 10F
BELOW NORMAL
- WARMING TEMPERATURES BEGIN SUNDAY AND CONTINUE THROUGH MIDWEEK
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850 MB TEMPS ARE FORECAST TO FALL FROM ABOUT +8C SATURDAY
MORNING TO ABOUT 2-3C SATURDAY EVENING. COOL NORTHWEST FLOW
WITH RATHER SIGNIFICANT LOW LEVEL COLD AIR ADVECTION EXPECTED TO
DAMPEN THE DIURNAL CYCLE ON SATURDAY WITH TEMPERATURES REACHING
THE LOWER TO MIDDLE 60S BY MIDDAY AND THEN REMAINING STEADY OR
PERHAPS FALLING STARTING IN THE MIDDLE AFTERNOON HOURS.
SHOWERS ASSOCIATED WITH THE TROUGH ARE MOST LIKELY IN THE
MORNING WITH DRYING EXPECTED IN THE AFTERNOON.
SUNDAY HEIGHTS RISE ABOUT 60 METERS BUT ONLY A MODEST REBOUND IN
TEMPERATURES IS EXPECTED WITH MINIMAL WARMING AT 850 MB TO ABOUT
+4C.
60 TO 100 METER HEIGHT RISES ARE EXPECTED MONDAY AS UPPER RIDGE
BUILDS FROM THE MISSISSIPPI RIVER VALLEY INTO THE GREAT LAKES.
850 MB MEAN TEMPS RISE TO +10C SO A DECENT JUMP IN TEMPERATURES
SHOULD PUSH US BACK TO ABOUT NORMAL.
HEIGHTS LIKELY KEEP RISING ANOTHER 40-70 METERS ON TUESDAY AND
THE UPPER RIDGE WILL LIKELY BE OVERHEAD INTO WEDNESDAY. ENSEMBLE
GUIDANCE HAS BEEN PERSISTENT IN BRINGING TEMPERATURES UP TO
ABOUT 10F ABOVE NORMAL BY MIDWEEK. THERE ARE ALWAYS FLIES IN THE
OINTMENT, AS SOME OF THE GUIDANCE DOES DEVELOP A CLOSED LOW
ALONG THE ATLANTIC COAST WHICH COULD LIMIT THE WARMING SOME. BUT
GIVEN THE RECENT COOL PERIOD, THERE IS STILL HIGH CONFIDENCE IN
MUCH WARMER WEATHER THAN THE 58F HIGH AT PITTSBURGH YESTERDAY.
THE LAST 80 DEGREE DAY AT KPIT WAS MAY 16TH, AND THERE IS A GOOD
SHOT OF 80 DEGREES OR MORE TUESDAY AND WEDNESDAY. NBM 25TH-75TH
PERCENTILE MAXT ON WEDNESDAY IS 84-90. SO IT APPEARS THAT JUNE
WILL BRING A TASTE OF SUMMER IF THE ENSEMBLES ARE ON THE MARK.
AVIATION /16Z THURSDAY THROUGH MONDAY/
VEERING BOUNDARY LAYER WIND AS MID-LEVEL TROUGH CONTINUES TO
SHIFT EAST OF THE REGION IS EXPECTED TO CONTINUE WEAK DRY
ADVECTION DURING THE MORNING HOURS TODAY. ENOUGH RADIATIONAL
COOLING HAS CREATED RAPID ONSET OF IFR OR LOWER FOG/STRATUS AT
MOST SITES SAVE AGC/MGW WHERE WIND HAS REMAINED JUST ELEVATED
ENOUGH TO PREVENT DENSE FOG DEVELOPMENT AND BOUNDARY LAYER
MOISTURE HAS MANIFESTED RATHER AS MVFR STRATUS. EXPECTATION IS
THAT ONCE MIXING COMMENCES AFTER 12Z, VIS SHOULD START TO
IMPROVE AT ALL SITES BUT LIKELY TAKE THE LONGEST TO CLEAR AT
ZZV/FKL/DUJ. CIGS, MEANWHILE, ARE FAVORED TO HOLD ON TO IFR OR
LOWER THROUGH 13-14Z, THOUGH MOST RECENT SATELLITE TRENDS
SUGGEST IT MAY BE SLIGHTLY QUICKER TIMING, AS MIXING ERODES THE
STRATUS DECK. EITHER WAY, A RETURN TO VFR BY LATE MORNING IS
HIGH CONFIDENCE AS CIGS RISE THROUGH THE DAY WITH DIURNAL CU
DECKS AROUND 6KFT. OCCASIONAL GUSTS UP TO 20 KTS CAN'T BE RULED
OUT THIS AFTERNOON BEFORE QUIETING OVERNIGHT.
OUTLOOK...
THE NEXT LOW PRESSURE SYSTEM WILL RETURN RAIN CHANCES AND
AREAWIDE RESTRICTIONS FRIDAY, WITH MODELS FAVORING HIGHEST
AVIATION IMPACTS EAST OF I-79. 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...CRAVEN
NEAR TERM...MILCAREK
SHORT TERM...CRAVEN
LONG TERM...CRAVEN
AVIATION...FRAZIER/MLB
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