821
FXUS61 KPBZ 211104
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
704 AM EDT THU AUG 21 2025
SYNOPSIS
DAYTIME TEMPERATURES WILL AGAIN BE NEAR NORMAL TODAY BEFORE
GRADUALLY INCREASING TO THE UPPER 80S BY SATURDAY. PRECIPITATION
CHANCES WILL BEGIN TO INCREASE THIS WEEKEND AS LOW PRESSURE
ADVANCES OUT OF THE WEST.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- LARGELY DRY CONDITIONS TODAY.
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AFTER A RELATIVELY WARM START TODAY THANKS TO PERSISTENT CLOUD
COVER BLANKETING THE REGION, TEMPERATURES WILL RISE TO NEAR
NORMAL VALUES BASED OFF LATEST 500MB HEIGHTS AND
THICKNESS VALUES . BOTH THE HREF AND NBM ENSEMBLES SHOW SUB 10%
HOURLY POPS OVER THE COURSE OF THE DAY.
WITH HURRICANE ERIN TO OUR EAST AND HIGH PRESSURE TO THE WEST,
SFC WINDS WILL BE OUT OF THE NORTHEAST, VEERING MORE EASTERLY BY
THIS EVENING.
SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/
KEY MESSAGES:
- DRY WEATHER CONTINUES WITH TEMPERATURES SLIGHTLY HIGHER
(MID-80S) ON FRIDAY.
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DRY CONDITIONS WILL CONTINUE FRIDAY WITH A WARMING TREND IN
TEMPERATURES AS HEIGHTS SLIGHTLY INCREASE ACROSS THE REGION.
FLOW WILL CONTINUE TO BE RELATIVELY LIGHT WITH AN EASTERLY
COMPONENT.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
KEY MESSAGES:
- ABOVE AVERAGE TEMPERATURES BRIEFLY RETURN SATURDAY.
- PRECIPITATION CHANCES RETURN SATURDAY INTO SUNDAY WITH A PASSING
COLD FRONT.
- COOLER WEATHER DURING FIRST HALF OF NEXT WEEK.
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AN APPROACHING COLD FRONT AND ASSOCIATED UPPER-LEVEL TROUGH
WILL INCREASE CHANCES OF PRECIPITATION THROUGH SATURDAY THROUGH SUNDAY.
OVERALL, RAINFALL ACCUMULATION TOTALS REMAIN RELATIVELY LOW
WITH THE CHANCE FOR > 0.25" IS 30%-40% FOR AREAS EAST OF
PITTSBURGH AND LESS THAN 25% CHANCE TO THE WEST.
GENERALLY HIGH CONFIDENCE EXISTS IN A PERSISTENT EASTERN CONUS
TROUGHING BY EARLY NEXT WEEK. THIS SHOULD KEEP TEMPERATURES BELOW
AVERAGE THROUGH THE FIRST HALF OF NEXT WEEK. BY TUESDAY, THERE IS A
FORECAST NORTHWESTERLY FLOW. WITH THE WARM LAKE WATERS ( 20C [68F]
OR WARMER) AND COOLER 850MB TEMPERATURES (5-8C [41-46F]), THERE IS A
CHANCE THAT LAKE-EFFECT RAIN SHOWERS COULD POP-UP TUESDAY AFTERNOON.
AVIATION /12Z THURSDAY THROUGH MONDAY/
SATELLITE AND SURFACE OBSERVATIONS CONFIRM WIDESPREAD STRATUS
COVERING THE REGION WITH HEIGHTS VARYING BETWEEN MVFR TO IFR
LEVELS AS OF 12Z. DIURNAL HEATING AND MIXING WILL FOSTER SLOW
RISES IN CLOUD HEIGHTS WITH HI-RES MODEL PROBABILITIES FAVORING
20Z (LESS THAN 40% CHANCE FOR MVFR) FOR MOST TERMINALS. HOWEVER,
POCKETS OF MVFR STRATOCU MAY LINGER AS THE 00Z SOUNDING SHOWS
ABUNDANT MOISTURE TRAPPED BENEATH A STRONG 850MB INVERSION
(WHICH IS PICKED UP ON BY HR-RES MODELS KEEPING 20-30%
PROBABILITIES FOR MVFR THROUGH 00Z).
MODELS SUGGEST EROSION OF THE STRATOCU DECK SHOULD OCCUR AFT 00Z
TO GIVE WAY AT LEAST TO JUST SCATTERED DECKS BETWEEN 2-5KFT. IF
THIS OCCURS, AREAS OF FOG MAY DEVELOP WITH STRONG RADIATIONAL
COOLING THAT FAVORS THE RIVER VALLEYS. BUT CONFIDENCE ISN'T HIGH
ON WIDESPREAD CLEARING TO OCCUR AS A STAGNATION OF FLOW WOULD
SUGGEST EROSION OF THE BOUNDARY LAYER MOISTURE MAY BE OVERPLAYED
BY DETERMINISTIC MODELS.
OUTLOOK...
VFR RETURNS FRIDAY AFTERNOON WITH DIURNAL HEATING/MIXING AND
CLOUD EROSION AS UPPER FLOW STRENGTHENS FROM THE SW AHEAD OF THE
NEXT UPPER LEVEL.
THAT TROUGH AND ASSOCIATED COLD FRONT WILL CROSS LATE SATURDAY
INTO SUNDAY. EXPECT INCREASED SHOWER/THUNDERSTORM CHANCES
FAVORING WESTERN PA AND THE WV HIGHER TERRAIN, LIKELY MVFR TO
LOCALIZED IFR CIGS AMID COLD ADVECTION IN THE POST FRONTAL
ENVIRONMENT (FAVORING SUNDAY/MONDAY MORNINGS), AND AN EVENTUAL
INCREASE IN W TO NW SURFACE WINDS.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...88
NEAR TERM...88
SHORT TERM...88
LONG TERM...88/LUPO
AVIATION...FRAZIER
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