344
FXUS61 KPBZ 210037
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
837 PM EDT SUN APR 20 2025
SYNOPSIS
DRY WEATHER IS EXPECTED THROUGH MIDNIGHT 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 /THROUGH MONDAY/
KEY MESSAGES:
- A FEW THUNDERSTORMS ARE POSSIBLE LATER TONIGHT.
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EVENING UPDATE:
HIGH PRESSURE WILL CONTINUE TO KEEP THE AREA DRY AT LEAST
THROUGH 03Z. THE WARM FRONT WILL BEGIN TO LIFT NORTH DURING THE
OVERNIGHT. THERE WILL BE A BIT OF ELEVATED INSTABILITY AND THUS
THE POTENTIAL FOR A FEW THUNDERSTORMS AFTER 04Z. THIS
DEVELOPMENT WILL CONTINUE THROUGH DAWN. WITH THE INSTABILITY AND
MID AND UPPER LEVEL CLOUD COVER, THIS WILL KEEP FOG TO A
MINIMUM.
PREVIOUS DISCUSSION:
INCREASE SUBSIDENCE IN THE WAKE OF THE COLD FRONT HAS CLEARED A
MAJORITY OF MID AND LOW-LEVEL CLOUDS ACROSS THE REGION.
TEMPERATURES WILL STILL TREND ABOVE-AVERAGE THIS AFTERNOON
DESPITE NORTHERLY FLOW AT THE SURFACE.
SURFACE WINDS WILL GRADUALLY SHIFT FROM NORTH TO SOUTHEAST
THROUGHOUT THE DAY AS A NEW LOW PRESSURE TRACKS INTO THE OHIO
RIVER VALLEY. MID AND UPPER-LEVEL CLOUDS WILL INCREASE FROM
SOUTH TO NORTH THIS EVENING, AHEAD OF AN EXPECTED WARM FRONT.
SHORT TERM /MONDAY NIGHT 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 /01Z MONDAY THROUGH FRIDAY/
VFR WILL CONTINUE THROUGH TOMORROW AFTERNOON. WINDS ARE
EXPECTED TO SHIFT FROM NORTHEAST TO SOUTHEAST AHEAD OF A WARM
FRONT.
A PASSING WARM FRONT EARLY TOMORROW MORNING MAY CREATE ISOLATED
RESTRICTIONS AND THUNDERSTORMS BETWEEN 06Z TO 10Z. PROB30 COVERS
LIGHTNING POTENTIAL IN THE VICINITY OF TERMINALS THAT COULD
EXPERIENCE IMPACTS. DURING THIS TIME, EXPECT BRIEF PERIODS OF
LOW-LEVEL WIND SHEAR FOR ABOUT 2 HOURS AT MOST TERMINALS.
THERE WILL BE A BRIEFING BREAK IN SHOWER AND THUNDERSTORM ACTIVITY
AHEAD OF A COLD FRONT. PROBABILITY OF LIGHTNING AND STRONG WINDS
EMBEDDED WITHIN THUNDERSTORMS INCREASES AFTER 17Z WITH A PRE-FRONTAL
TROUGH FOLLOWED BY THE COLD FRONT.
DURING THE COLD FRONT PASSAGE, EXPECT SOME TEMPORARY PERIODS OF MVFR
CEILINGS. AT FKL AND DUJ, EXPECT MVFR CIGS TO SETTLE INTO THE AREA
THROUGH TUESDAY MORNING.
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...HEFFERAN/SHALLENBERGER
SHORT TERM...HEFFERAN
LONG TERM...FRAZIER
AVIATION...HEFFERAN/LUPO
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