532
FXUS61 KPBZ 210625
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
225 AM EDT MON APR 21 2025
SYNOPSIS
DRY WEATHER IS EXPECTED EARLY TONIGHT UNDER HIGH PRESSURE.
SCATTERED SHOWERS AND THUNDERSTORMS WILL RETURN EARLY MONDAY
WITH A PASSING WARM FRONT. SHOWERS AND GUSTY THUNDERSTORMS ARE
EXPECTED WITH A COLD FRONT MONDAY AFTERNOON.
NEAR TERM /UNTIL 6 AM THIS MORNING/
KEY MESSAGES:
- DRY EARLY
- A FEW THUNDERSTORMS ARE POSSIBLE LATER TONIGHT.
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A WARM FRONT WILL LIFT NORTH ACROSS THE REGION OVERNIGHT, AS A
VORT MAX ALOFT CROSSES THE UPPER OHIO VALLEY REGION. AFTER
INITIALLY DRY WEATHER, ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF THE
FRONT. ELEVATED INSTABILITY IS EXPECTED, WITH SHOWALTER INDICES
OF -1, THOUGH WITH THIS LIMITED INSTABILITY NO STRONG STORMS
ARE EXPECTED. TEMPERATURES SHOULD REACH THEIR OVERNIGHT LOWS
EARLY TONIGHT, WITH TEMPERATURES RISING IN WARM ADVECTION LATER
TONIGHT.
SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/
KEY MESSAGES:
- WARM FRONT RETURNS EARLY MONDAY MORNING, BEFORE DAWN
- SHOWERS AND GUSTY THUNDERSTORMS MONDAY AFTERNOON/EVENING WITH
A COLD FRONT
- DRY TUESDAY UNDER HIGH PRESSURE
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THE PROBABILITY OF SHOWERS AND ISOLATED THUNDERSTORMS INCREASES
TO 35-50% WITH A PASSING WARM FRONT BETWEEN 2AM TO 4AM MONDAY
MORNING. WITH ELEVATED INSTABILITY RANGING BETWEEN 300J/KG TO
700J/KG AND EFFECTIVE SHEAR NEAR 35KTS, SMALL HAIL COULD BE
OBSERVED IN ISOLATED THUNDERSTORMS. HOWEVER, CONFIDENCE AT THE
MOMENT IS CONSIDERED LOW GIVEN HIGH RESOLUTION MODELS SHOWING A
LARGE RANGE IN THE AVAILABLE INSTABILITY ALOFT, SOME MODELS GO
AS HIGH AS 1000J/KG WHILE OTHERS SUGGEST ONLY 300J/KG. IF ONE
WERE TO SEE EXPERIENCE LIGHTNING AND HAIL, IT WOULD LIKELY BE
NEAR I-80.
IN THE WAKE OF THE WARM FRONT, THERE WILL LIKELY BE A PERIOD
WHERE PRECIPITATION CHANCES REMAIN LOW. MOSTLY BETWEEN 6AM TO
12PM, AHEAD OF A COLD FRONT.
THE TROUGH AND ASSOCIATED SURFACE COLD FRONT ARE PROGGED TO
ADVANCE EASTWARD EARLY MONDAY AFTERNOON. A BAND OF SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF THE
FRONT, WITH INCREASING MOISTURE AND VORTICITY ADVECTION. A
PRE-FRONTAL TROUGH COULD ALSO RESULT IN ADDITIONAL
SHOWERS/STORMS AHEAD OF THE MAIN FRONT. A JET ALOFT WILL ALSO
ENHANCE ASCENT, AS WELL AS SHEAR. CAPE WILL ALSO INCREASE AHEAD
OF THE FRONT, WITH CURRENT HREF PROGS BETWEEN 500 AND 1000 J/KG.
THE AMOUNT OF DESTABILIZATION THAT OCCURS WILL DEPEND ON THE
TIMING OF THE FRONT, AND THE EFFECTS A PREFRONTAL TROUGH WILL
HAVE ON THE ATMOSPHERE, THOUGH AT THIS TIME IT APPEARS THERE IS
AT LEAST SOME POTENTIAL FOR GUSTY WIND (40-45MPH) IN STORMS
BETWEEN 2PM TO 6PM.
SHOWER AND THUNDERSTORM CHANCES WILL END FROM WEST TO EAST
MONDAY EVENING (BETWEEN 7PM TO 9PM) IN THE WAKE OF THE COLD
FRONT.
DRY WEATHER RETURNS TUESDAY AS SURFACE HIGH PRESSURE BUILDS
ACROSS THE UPPER OHIO VALLEY REGION.
TEMPERATURES ARE EXPECTED TO AVERAGE ABOVE SEASONABLE LEVELS
THROUGH THE PERIOD.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
KEY MESSAGES:
- ABOVE NORMAL TEMPERATURE FOR THE END OF THE WEEK BEFORE A
POTENTIAL WEEKEND COOL OFF.
- TRENDING TOWARDS A WETTER LATER HALF OF WEEK AND START TO THE
WEEKEND.
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CONFIDENCE IS FAIRLY HIGH ON SUBTLE TENNESSEE RIVER VALLEY
RIDGING ALOFT COMBINING WITH SURFACE HIGH PRESSURE TO PROMOTE
DRY WEATHER WEDNESDAY. TEMPERATURE IS LIKELY TO BE ABOVE NORMAL,
BUT THE DEGREE OF HEATING WILL DEPEND ON RIDGE STRENGTH
(STRONGER EQUATES TO WARMER) OR INFLUENCE OF SHORTWAVE MOVEMENT
TO THE NORTH (LOWERS HEIGHTS AND INCREASES CLOUD COVER TO
DECREASE TEMPERATURE).
ENSEMBLE MODELS ARE TRENDING TOWARD A WETTER OUTLOOK TO END THE
WEEK AS POTENTIAL SHORTWAVE MOVEMENT INCREASES WITHIN THE
QUASI-ZONAL TO WEAKLY SOUTHWEST FLOW OVERHEAD. THERE REMAINS
VARIATIONS ON SHORTWAVE TIMING AND WHETHER MOVEMENT FROM THE SW
IS ABLE TO PHASE WITH TROUGH ACTIVITY IN SOUTHERN CANADA, BUT
CURRENT CLUSTER ANALYSIS SUGGESTS TOTAL ACCUMULATIONS ARE NOT
LIKELY TO BE IMPACTFUL AND ENVIRONMENTAL CONDITIONS WILL
STRUGGLE TO SUPPORT HAZARDOUS WEATHER.
FROM THERE, ENSEMBLE MEANS SUGGEST A MORE ORGANIZED NORTHERN
STREAM TROUGH WILL DROP TOWARD THE NORTHEAST U.S. NEXT WEEKEND AS
RIDGE DEVELOPMENT OCCURS OVER THE CENTRAL PLAINS. THIS PATTERN
FAVORS NEAR TO SLIGHTLY BELOW AVERAGE TEMPERATURE AND DRIER
WEATHER, BUT LARGE VARIATIONS IN TROUGH DEPTH/PROGRESSION WILL
PLAY ROLE IN THE DEGREE OF COOLING/DRYING AS WELL AS HOW QUICKLY
WARM WEATHER RETURNS THE FOLLOWING WEEK.
AVIATION /06Z MONDAY THROUGH FRIDAY/
A FEW SCATTERED SHOWERS HAVE FORMED GENERALLY NORTH AND WEST OF
THE PIT/AGC/BVI AREA TO START THE TAF PERIOD AS A WARM FRONT
MAKES ITS WAY THROUGH THE AREA. THESE WILL CONTINUE TO MOVE
NORTHEASTWARD, POTENTIALLY BRINGING VERY BRIEF PERIODS OF -RA
AT THESE SITES AS WELL AS FKL AND DUJ THROUGH EARLY MORNING.
HOWEVER, LITTLE IMPACT IS EXPECTED DUE TO DRY NEAR-SURFACE AIR
PROMOTING SUB-CLOUD EVAPORATION AND THEREFORE LIMITING ANY
DROPS IN VISIBILITIES OR CEILINGS. FOR NOW, THE PROBABILITY OF
LIGHTNING OCCURRING IN THESE SHOWERS REMAINS TOO LOW TO WARRANT
INCLUDING IN TAFS, HOWEVER IT IS NOT OUT OF THE REALM OF
POSSIBILITY (~30% CHANCE OR LOWER).
THERE WILL BE A BRIEFING BREAK IN SHOWER AND THUNDERSTORM
ACTIVITY DURING MID TO LATE MORNING HOURS AHEAD OF AN
APPROACHING COLD FRONT. HEAVIER SHOWERS INCREASE IN COVERAGE
AHEAD OF THE FRONT AFTER 17Z (CLOSER TO 15Z AT ZZV) AS A PRE-
FRONTAL TROUGH ENTERS THE AREA. EMBEDDED THUNDERSTORMS WILL ALSO
BE POSSIBLE AS PROBABILITIES FOR THUNDER INCREASE TO 30-50%,
THOUGH THESE ARE STILL TOO LOW TO WARRANT A PREVAILING MENTION
IN TAFS, SO OPTED INSTEAD TO GO WITH PREVAILING -SHRA AND
PROB30'S WITH -TSRA. STRONG WIND GUSTS AND RESTRICTIONS MAY
ACCOMPANY THE HEAVIER SHOWERS AND THUNDERSTORMS.
THE COLD FRONT ITSELF MOVES THROUGH FOLLOWING THE PRE-FRONTAL
TROUGH, WITH SOME POTENTIAL FOR A QUASI-SQUALL LINE FEATURE
ALONG THE FRONT IF INSTABILITY WARRANTS. THE FRONTAL PASSAGE
WILL MARK THE END OF PRECIPITATION AS WINDS VEER TO WESTERLY OR
NORTHWESTERLY. SOME PERIODS OF MVFR CEILINGS MAY FOLLOW THE
FRONT, PARTICULARLY CLOSER TO THE HIGHER TERRAIN AND NORTH OF
I-80 WHERE UPSLOPE FLOW AND INFLUENCE FROM LAKE ERIE,
RESPECTIVELY, WILL CONTINUE TO PROMOTE LOW CLOUD DEVELOPMENT.
OUTLOOK...
VFR AND MOSTLY DRY WEATHER RETURN TUESDAY AND WEDNESDAY,
FOLLOWED BY ANOTHER WEATHER SYSTEM BRINGING INCREASING CHANCES
FOR RAIN AND RESTRICTIONS LATE THIS WEEK.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...HEFFERAN
NEAR TERM...WM
SHORT TERM...HEFFERAN
LONG TERM...FRAZIER
AVIATION...CERMAK
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