644
FXUS61 KPBZ 311641
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1241 PM EDT SAT MAY 31 2025
SYNOPSIS
OCCASIONAL LIGHTER RAIN SHOWERS AND UNSEASONABLY COOL
TEMPERATURE IS EXPECTED THROUGH EARLY SATURDAY AFTERNOON IN THE
WAKE OF AN EXITING LOW PRESSURE SYSTEM. DRY WEATHER AND RAPIDLY
RISING TEMPERATURE WILL FOLLOW THROUGH EARLY NEXT WEEK, AS HIGH
TEMPERATURE HITS ABOVE NORMAL READINGS BY TUESDAY.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGES:
- FLOODING RISK IS WANING AS THE LOW PRESSURE SYSTEM DRIFTS EAST
OF THE REGION, THOUGH AREAL RIVER RISES MAY CONTINUE INTO
SATURDAY MORNING.
- ADDITIONAL LIGHTER RAIN SHOWERS AND LOW PROBABILITY THUNDER
REMAIN POSSIBLE INTO EARLY SATURDAY AFTERNOON.
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UPDATED TO ACCOUNT FOR SOUTHEASTWARD-MOVING SHOWERS/ISOLATED
THUNDERSTORMS AHEAD OF THE SURFACE COLD FRONT. IN-PROGRESS 12Z
PBZ SOUNDING SHOWS SKINNY CAPE PROFILES TOPPING OUT IN THE -10C
TO -15C RANGE, ALLOWING FOR SOME LIGHTNING GENERATION. THESE
SHOWERS/STORMS MAY LOCALLY PRODUCE A TENTH OF AN INCH OR TWO OF
RAIN, BUT SHOULD NOT EXACERBATE ANY LINGERING HIGH WATER
CONCERNS.
PREVIOUS DISCUSSION...
WEAK SHORTWAVE MOVEMENT IN NW FLOW COMBINED WITH LAKE
ENHANCEMENT DUE TO COLD ADVECTION AND THE MORNING ARRIVAL OF A
SURFACE COLD FRONT WILL MAINTAIN PERIODIC RAIN CHANCES THROUGH
THE EARLY AFTERNOON. AS 850MB TEMPERATURE FALLS TOWARD 2 TO 4
DEGREES CELSIUS WITH SHORTWAVE MOVEMENT, LAPSE RATES WILL
STEEPEN AND FREEZING LEVELS FALL WHICH MAY ALLOW FOR ISOLATED
THUNDERSTORM GENERATION. CANNOT RULE OUT A STRONGER TO
MARGINALLY SEVERE STORM IN THE FAR SOUTHEASTERN CWA IN THE AREA
OF TUCKER COUNTY IF DEEPER INSTABILITY CAN BE REALIZED THERE
AHEAD OF THE CROSSING COLD FRONT. THE DEEPER MIXING AS A RESULT
OF THAT COLD ADVECTION WILL FOSTER BREEZY CONDITIONS, WITH MANY
LOCATIONS SEEING AFTERNOON GUSTS BETWEEN 25 TO 35 MPH, BEFORE
FALLING AROUND SUNSET.
BY THE EVENING, DRY ADVECTION AND SUBSIDENCE WILL QUICKLY
DISSIPATE SHOWER DEVELOPMENT AND RESULT IN DRY CONDITIONS BY
TONIGHT. DAYTIME TEMPERATURE IS UNLIKELY TO RISE NOTABLY GIVEN
STRONG LATE SEASON COLD ADVECTION AND LIMITED INSOLATION,
LEAVING READINGS UPWARDS OF 20 DEGREES BELOW THE DAILY AVERAGE.
THOUGH RECORDS ARE NOT LIKELY TO BE BROKEN, IT IS LIKELY MANY
SITE SEE READINGS WITHIN THE TOP 5 LOWEST FOR MAXIMUM
TEMPERATURE ON RECORD.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
KEY MESSAGES:
- WARMING TREND WITH PREDOMINANTLY DRY WEATHER.
- SHOWERS LATE MONDAY COULDN'T BE RULED OUT NORTHEAST OF
PITTSBURGH.
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THE SHORT TERM FLOW PATTER REMAINS HIGH CONFIDENCE. A EASTERN
TROUGH WILL BE REPLACED WITH RIDGING, CLEARING SKIES SUNDAY AND
LEADING TO A TEMPERATURE REBOUND. HEATING UNDER SUBSIDENCE WILL
LEAD TO WELL MIXED SURFACE PROFILES, WITH POTENTIALLY A WEAK
SUBSIDENCE INVERSION OVERHEAD. WITH CLEAR SKIES AND TAPPING INTO
THIS LAYER, OPTED TO RAISE TEMPERATURES A COUPLE DEGREES OVER
GUIDANCE DURING THE DAY, AND LOWER DEW POINTS A HAIR. THIS MAY
STILL RESULT IN BELOW NORMAL TEMPERATURES, BUT THE AIR MAY FEEL
QUITE DRY.
INTO SUNDAY NIGHT, CLEAR SKIES ARE EXPECTED TO PREVAIL WITH A
RELAXATION IN WINDS WHICH MAY LEAD TO TEMPERATURES ENDING UP
NEAR FROST CRITERIA NORTH OF PITTSBURGH WITH EFFICIENT
RADIATIVE COOLING. NBM PROBS REMAIN <10%, BUT TEMPERATURES TEND
TO UNDERPREFORM IN VALLEYS AND SHELTERED AREAS WHEN ALL FROST
INDICATORS ARE FAVORABLE.
MONDAY WILL SEE CONTINUED RIDGING AND A RETURN TO NEAR NORMAL
TEMPERATURES, THOUGH THERE IS SOME INDICATION SMOKE ALOFT MAY
RETURN WHICH COULD STAVE A COUPLE OF DEGREES OFF HIGHS. WITH
LOWER DEW POINTS, MORE DRY SURFACE CONDITIONS ARE FORECAST. A
SUBSET OF ENSEMBLE MEMBERS HAVE A FAST WEAK WAVE NORTHEAST OF
PITTSBURGH WHICH MAY RESULT IN A LOW PROBABILITY OF CLOUD COVER
AND PERHAPS A QUICK RAIN SHOWER, BUT WITH SURFACE PROFILES SO
DRY, THERE IS ALSO THE CHANCE THAT EVEN WITH FORCING, THAT
PRECIPITATION WILL NOT MAKE IT TO THE GROUND. STUCK WITH NBM
POPS FOR NOW. FROST CONCERNS ARE NULL MONDAY NIGHT WITH DEW
POINT RISES KEEPING LOWS WELL ABOVE THE 30S NECESSARY FOR
FORMATION.
LONG TERM /TUESDAY THROUGH FRIDAY/
KEY MESSAGES:
- WARM TEMPERATURES THIS WEEK WITH MODERATE HEAT RISK BY
WEDNESDAY AND THURSDAY.
- RAIN AND SEVERE CHANCES AGAIN LATE-WEEK.
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CONTINUED RIDGING IS FORECAST WITH HIGH CONFIDENCE. ENSEMBLE
CLUSTERS HAVE VERY LITTLE VARIABILITY AROUND THE PITTSBURGH
AREA, WITH HEIGHT MAXS AROUND 588 DM LATE TUESDAY INTO
WEDNESDAY. THIS WOULD GENERALLY TRANSLATE TO A FORECAST IN THE
UPPER 80S FOR DAYTIME HIGHS. MODELING THESE RIDGING PATTERNS IN
THE EAST TYPICALLY COME WITH SOME ISSUES MODELING THE EXTEND OF
CLOUD COVER AND MAYBE DAYTIME CONVECTION; ADD ON THERE MAY THE
THE INFLUENCE OF SMOKE ALOFT DURING THIS PERIOD. THIS WILL
CREATE SOME LOWER PROBABILITY "COOLER SOLUTIONS" OF LOW 80S
TUESDAY/THURSDAY WITH MID-80S WEDNESDAY.
THE MORE HIGH PROBABILITY SCENARIO IS MOSTLY CLEAR AND DRY
WEATHER UNDER RIDGING, PUSHING DAYTIME HIGHS INTO THE MID-TO-
UPPER 80S FOR THIS PERIOD, WITH WEDNESDAY LIKELY THE WARMEST
DAY. CHANCES OF >80F ALL THREE DAYS ARE 80% TO 100% APART FOR
THE RIDGES, AND CHANCES OF >90F ARE ~50% FOR PITTSBURGH AND
RIVER VALLEYS WEDNESDAY AND THURSDAY, AND AS HIGH AT 80% FOR THE
OHIO RIVER VALLEY ALONG THE OHIO/WV BORDER. URBAN EFFECTS MAY
INCREASE THESE PROBABILITIES LOCALLY. COMBINE THIS WITH
OVERNIGHT LOWS ONLY GETTING TO THE UPPER 60S TO LOW 70S, HEAT
RISK INCREASES TO MODERATE LEVELS WEDNESDAY AND THURSDAY.
CONFIDENCE IN THE FORECAST IS HIGHER WEDNESDAY THAN THURSDAY
WITH SOME CLOUD AND PRECIPITATION TIMING UNCERTAINTY WITH THE
NEXT DISTURBANCE.
PRECIPITATION SPREAD IS THE HIGHEST THURSDAY AND FRIDAY,
INDICATING SOME SUBTLE DIFFERENCES IN TIMING THE NEXT RAIN
CHANCES. SOME SEVERE CHANCES COME WITH THIS WAVE, AS EVIDENCED
IN A 5% TO 15% CHANCE WITHIN 25MILES ON THE CSU-MLP PRODUCT.
CHANCES OF RAIN >1" ARE LOW (AROUND 15%) FOR NOW, THOUGH LIKELY
A TAD LOW DUE TO THE AFOREMENTIONED TIMING UNCERTAINTY. THIS
SHOULD BRING SOME RELIEF, HEIGHT FALLS, AND A RETURN TO MORE
QUASI-ZONAL FLOW, WITH MOST OF THE TEMPERATURE SPREAD NEXT
WEEKEND ENCOMPASSED IN THE 70S FOR HIGHS.
AVIATION /16Z SATURDAY THROUGH WEDNESDAY/
WIDESPREAD MVFR/IFR CEILINGS ARE IN PLACE, THANKS TO LINGERING
LOW-LEVEL MOISTURE AND CONVERGENCE AHEAD OF THE CROSSING COLD
FRONT. A COUPLE OF ISOLATED THUNDERSTORMS ARE ALSO OCCURING,
GIVEN SKINNY CAPE PROFILES ALLOWING FOR SUFFICIENTLY COLD CLOUD
TOPS FOR LIGHTNING GENERATION.
ADDITIONAL SHORTWAVE MOVEMENT IN NW FLOW PLUS COLD ADVECTION
WILL FOSTER ADDITIONAL SCATTERED RAIN SHOWERS FAVORING PIT AND
SE THROUGH 18Z BEFORE TAPERING OFF. COLD AIR ALOFT MAY ALLOW FOR
ADDITIONAL ISOLATED THUNDERSTORMS DESPITE WEAK INSTABILITY, BUT
CONFIDENCE IN COVERAGE IS TOO LOW TO MENTION. CEILINGS WILL
IMPROVE SLOWLY THIS MORNING, RISING TO MVFR BEFORE IMPROVING TO
VFR THIS AFTERNOON. FRONTAL PASSAGE AND THE RESULTANT
STEEPENING OF LOW- LEVEL LAPSE RATES WILL FOSTER GUSTY NW WIND
BETWEEN 25 TO 35 MPH WITH OCCASIONAL GUSTS UP TO 40 MPH IN THE
HIGHER TERRAIN.
PAST 00Z, DRY ADVECTION AND INCREASING SUBSIDENCE WITH
APPROACHING SURFACE HIGH PRESSURE WILL END ANY LINGERING
PRECIPITATION, AND ALLOW FOR VFR CONDITIONS OVERNIGHT. WILL
NEED TO ASSESS POTENTIAL FOR FOG OVERNIGHT, PARTICULARLY IN
AREAS THAT RECENTLY RECEIVED HEAVY RAIN.
OUTLOOK...
THERE IS HIGH CONFIDENCE (GREATER THAN 90% PROBABILITY) IN VFR
BY 00Z SUNDAY UNDER THE INFLUENCE OF HIGH PRESSURE AND DRY
ADVECTION. THESE CONDITIONS ARE LIKELY TO PERSIST UNDER RIDGE
BUILDING TO START THE NEXT WEEK.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...FRAZIER
NEAR TERM...FRAZIER/CL
SHORT TERM...MILCAREK
LONG TERM...MILCAREK
AVIATION...FRAZIER/CL
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