772
FXUS61 KPBZ 200931
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
531 AM EDT SUN APR 20 2025
SYNOPSIS
DRY WEATHER IS EXPECTED TODAY AS HIGH PRESSURE BUILDS IN.
SCATTERED SHOWERS AND THUNDERSTORMS WILL RETURN TONIGHT AS A
WARM FRONT MOVES NORTH ACROSS THE REGION. SHOWERS AND POSSIBLE
GUSTY THUNDERSTORMS ARE EXPECTED WITH A MONDAY COLD FRONT,
BEFORE DRY WEATHER RETURNS BY MID WEEK.
NEAR TERM /UNTIL 6 PM THIS EVENING/
KEY MESSAGES:
- DRY AND COOLER TODAY
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RIDGING WILL BUILD ACROSS THE REGION TODAY, WITH DRY WEATHER
EXPECTED. LOW LEVEL CLOUDS WILL CONTINUE TO ERODE FROM N-S THIS
MORNING, THOUGH MID AND HIGH CLOUDS WILL CONTINUE TO STREAM
ACROSS THE REGION AS WARM ADVECTION ALOFT BEGINS AGAIN LATER
TODAY. HIGH TEMPERATURES WILL BE 15 TO 20 DEGREES COOLER THAN ON
SATURDAY, THOUGH STILL A FEW DEGREES ABOVE SEASONABLE LEVELS.
SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/
KEY MESSAGES:
- WARM FRONT RETURNS SCATTERED SHOWERS/STORMS TONIGHT
- SHOWERS AND GUSTY THUNDERSTORMS MONDAY WITH A COLD FRONT
- DRY TUESDAY AND TUESDAY NIGHT
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THE RIDGE WILL MOVE EAST THIS EVENING, AS A TROUGH OVER THE
UPPER MIDWEST MOVES EAST. THE RESULTING SW FLOW ALOFT AHEAD OF
THE TROUGH WILL BRING A WARM FRONT BACK NORTH TONIGHT. SCATTERED
SHOWERS AND THUNDERSTORMS ARE EXPECTED WITH INCREASING MOISTURE
AND ASCENT IN SW FLOW ALOFT, AND WITH ELEVATED INSTABILITY
(SHOWALTER INDEX AROUND -1.) THE SCATTERED SHOWERS/STORMS
SHOULD END MONDAY MORNING AS THE FRONT LIFTS TO THE NORTH.
THE TROUGH AND ASSOCIATED SURFACE COLD FRONT ARE PROGGED TO
ADVANCE EASTWARD ON MONDAY. A BAND OF SHOWERS AND THUNDERSTORMS
ARE EXPECTED TO DEVELOP ALONG AND AHEAD OF THE FRONT, WITH
INCREASING MOISTURE AND VORTICITY ADVECTION. A PREFRONTAL 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 IN STORMS THAT DEVELOP MONDAY MAINLY IN THE
AFTERNOON.
SHOWER AND THUNDERSTORM CHANCES WILL END FROM W-E MONDAY
EVENING AS FROPA OCCURS. DRY WEATHER WILL THEN CONTINUE TUESDAY
AND TUESDAY NIGHT AS SURFACE HIGH PRESSURE BUILDS ACROSS THE
UPPER OHIO VALLEY REGION, UNDER ZONAL FLOW ALOFT. TEMPERATURES
ARE EXPECTED TO AVERAGE ABOVE SEASONABLE LEVELS THROUGH THE
PERIOD.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
KEY MESSAGES:
- SEASONABLY WARM WEATHER CONTINUES
- PRECIPITATION CHANCES DEPENDENT ON SHORTWAVE MOVEMENT AND
RIDGE LOCATION
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MODEL ENSEMBLES INDICATE A NEARLY ZONAL FLOW ALOFT WILL CONTINUE
THROUGH MID WEEK, AS SURFACE HIGH PRESSURE SLIDES EAST ACROSS
THE UPPER OHIO VALLEY REGION. THIS SHOULD MAINTAIN DRY AND
WARMER THAN AVERAGE WEATHER THROUGH EARLY THURSDAY. THE UPPER
AIR PATTERN IS PROGGED TO BEGIN TO AMPLIFY BY LATE WEEK, AS A
TROUGH DEVELOPS ACROSS THE PLAINS. A LEAD SHORTWAVE IN SW FLOW
ALOFT AHEAD OF THE APPROACHING TROUGH SHOULD RESULT IN
INCREASING SHOWERS CHANCES LATER THURSDAY INTO FRIDAY AS IT
CROSSES THE UPPER OHIO VALLEY REGION.
THE MAIN TROUGH, AND AN ASSOCIATED SURFACE COLD FRONT, IS
EXPECTED TO APPROACH AND CROSS THE REGION FRIDAY AND FRIDAY
NIGHT, WITH SHOWERS LIKELY. THE RAIN COULD LINGER INTO SATURDAY,
DEPENDING ON THE SPEED OF THE TROUGH AND SURFACE FRONT.
TEMPERATURES SHOULD CONTINUE TO AVERAGE ABOVE SEASONABLE LEVELS
THROUGH THE PERIOD.
AVIATION /10Z SUNDAY THROUGH THURSDAY/
A COLD FRONT CONTINUES TO SLOWLY CREEP SOUTHEAST THROUGH THE
AREA TO START THE TAF PERIOD, THOUGH SHOWERS AND THUNDERSTORMS
HAVE COME TO AN END. THERE IS CURRENTLY A MIX OF VFR CEILINGS
SOUTH OF THE FRONT AND MVFR CEILINGS NORTH OF IT, WITH THOSE
LOWER CEILINGS ADVANCING SOUTHWARD IMMEDIATELY BEHIND THE
FRONT. THEREFORE, EXPECTING MOST SITES (SAVE FOR PERHAPS ZZV)
WILL SEE AT LEAST A BRIEF PERIOD OF MVFR BEFORE SUNRISE. THIS
WILL BE FOLLOWED BY QUICK IMPROVEMENT TO VFR BY MID MORNING AS
CLOUDS SCATTER OUT. VFR THEN PREVAILS THEREAFTER THROUGH THE
REMAINDER OF THE TAF PERIOD.
THE COLD FRONT PASSAGE MAY BRING A BRIEF INCREASE IN WINDS AS
THEY SHIFT TO NORTHWESTERLY AROUND 8 TO 12 KNOTS WITH GUSTS TO
18 TO 23 KNOTS. HOWEVER, GUSTS SHOULD SETTLE FAIRLY QUICKLY AND
LIGHT NORTH WINDS THEN PREVAIL DURING THE DAY, SHIFTING TO MORE
NORTHEASTERLY BY THIS EVENING AND THEN EASTERLY OVERNIGHT
TONIGHT.
OUTLOOK...
A PASSING WARM FRONT EARLY MONDAY MAY CREATE ISOLATED
RESTRICTIONS AND THUNDERSTORMS, FOLLOWED BY HIGHER CHANCES FOR
RAIN AND RESTRICTIONS DURING THE DAY MONDAY WITH THE PASSAGE OF
A COLD FRONT. 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...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...CERMAK/CL/SHALLENBERGER
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