680
FXUS61 KPBZ 042347
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
747 PM EDT FRI APR 4 2025
SYNOPSIS
AN ACTIVE PATTERN CONTINUES THROUGH THE WEEKEND WITH MULTIPLE
ROUNDS OF SHOWERS AND THUNDERSTORMS. SEVERE STORMS WILL BE
POSSIBLE SATURDAY.
NEAR TERM /THROUGH SATURDAY/
KEY MESSAGES:
- FLOOD WATCH REMAINS IN EFFECT FOR PORTIONS OF THE REGION.
- SHOWERS AND THUNDERSTORMS RESUME TONIGHT.
-
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A BRIEF LULL IN ACTIVITY CONTINUES THIS AFTERNOON AS THE MAIN
AXIS OF PRECIPITATION REMAINS SOUTH OF THE AREA ALONG A STALLED
FRONTAL BOUNDARY. AREAL FLOODING FROM OVERNIGHT RAINFALL HAS
MOSTLY SUBSIDED GIVEN DAYTIME DRY CONDITIONS. HOWEVER,
ADDITIONAL RAINFALL OVERNIGHT AND SATURDAY WILL EXACERBATE
ALREADY WET CONDITIONS, AND WILL LIKELY LEAD TO ADDITIONAL AREAS
OF FLOODING. A FLOOD WATCH REMAINS IN EFFECT FOR THE SOUTHERN
HALF OF THE AREA THROUGH SUNDAY MORNING.
AREAS ALONG AND NORTH OF I-80 SAW PATCHY SUNSHINE LATE THIS
MORNING INTO THE AFTERNOON AS THE LOWER CLOUD DECK SHIFTED TO
THE SOUTH. THIS ALLOWED TEMPERATURES NORTH OF PITTSBURGH TO RUN
SEVERAL DEGREES WARMER THAN SOUTHERN PORTIONS OF THE AREA.
HOWEVER, LOWER CLOUDS ARE BEGINNING TO MOVE BACK INTO THE AREA,
CUTTING OFF MUCH ADDITIONAL HEATING.
UPPER LEVEL HEIGHT RISES ARE EXPECTED THIS AFTERNOON AS A LARGE
UPPER LOW DIGS SOUTH OF THE FOUR CORNERS REGION AND A LARGE
500MB HIGH MOVES OVER THE SOUTHEASTERN US. THE RIDGING WILL PUSH
THE SURFACE HIGH TO THE NORTHEAST AND ALLOW THE STALLED FRONT
TO BEGIN TO SLOWLY MOVE NORTHWARD FROM THE MID-ATLANTIC REGION
AS EVENING APPROACHES. ANOTHER SURFACE LOW IS THEN EXPECTED TO
TRACK NE OUT OF THE MISSISSIPPI VALLEY REGION OVERNIGHT. THIS
WILL ALLOW SHOWERS (AND PERHAPS A RUMBLE OF THUNDER) TO LIFT
NORTHWARDS LATER THIS AFTERNOON AND INTO THE OVERNIGHT. CAMS ARE
FAIRLY SPARSE IN COVERAGE DURING THE AFTERNOON, BUT SHOW BETTER
ORGANIZATION AFTER MIDNIGHT WITH CROSSING WARM FRONT. A FEW
OVERNIGHT STORMS MAY BECOME SEVERE, AND SPC HAS MAINTAINED A
MARGINAL RISK OF SEVERE WEATHER FOR LOCATIONS WEST OF
PITTSBURGH, PRIMARILY FOR HAIL AND DAMAGING WIND.
SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/
KEY MESSAGES:
- ROUNDS OF SHOWERS AND THUNDERSTORMS CONTINUE INTO THE WEEKEND.
- A FLOOD WATCH REMAINS IN EFFECT FOR PORTIONS OF THE REGION.
- SEVERE WEATHER IS POSSIBLE SATURDAY.
- A COLD FRONT ON SUNDAY WILL FINALLY BRING AN END TO THE HEAVY
RAINFALL THREAT.
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ANOTHER ROUND OF CONVECTION WILL CROSS THE AREA AROUND AND AFTER
SUNRISE SATURDAY MORNING WITH THE CROSSING WAVE. ENVIRONMENTAL
PARAMETERS WILL MAINTAIN A MARGINAL SEVERE THREAT, AGAIN
PRIMARILY FOR WIND AND HAIL. SOME CLEARING IS POSSIBLE BY LATE
MORNING/EARLY AFTERNOON AS THIS SHIFTS EAST, SETTING THE STAGE
FOR ANOTHER ROUND LATER SATURDAY AFTERNOON AND EVENING AHEAD OF
THE COLD FRONT.
CAMS HAVE BACKED OFF A BIT ON SEVERE POTENTIAL SATURDAY
AFTERNOON/EVENING WITH THE FRONT, WITH THE THREAT CONTINGENT ON
LATE MORNING CLEARING AND DESTABILIZATION. EARLIER RUNS
HIGHLIGHTED POSSIBLE DISCRETE CELLS AHEAD OF THE FRONT, WHICH
WOULD ENHANCE THE SEVERE RISK, BUT THE TREND HAS BEEN TOWARDS A
MORE LINEAR MODE AND LOWER PROBABILITIES FOR DESTABILIZATION.
STILL, IF STORMS ARE ABLE TO ORGANIZE IN THE LATE AFTERNOON,
HODOGRAPHS ARE SUPPORTIVE OF AT LEAST A MARGINAL TORNADO THREAT.
SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO SATURDAY NIGHT AND
EARLY SUNDAY AS LOW PRESSURE CROSSES, BUT THE STALLED FRONT
REMAINS. RAPID HEIGHT FALLS ON SUNDAY WILL FINALLY SHUNT THE
SURFACE RIDGE OVER THE SOUTHEAST AND ALLOWING A COLD FRONT TO
CROSS THE AREA BY SUNDAY NIGHT/EARLY MONDAY -- FINALLY BRINGING
AN END TO WIDESPREAD RAINFALL. AS TEMPERATURES COOL BEHIND THE
FRONT, LINGERING PRECIPITATION MAY BRIEFLY TRANSITION TO SNOW
FOR AREAS NORTH OF PITTSBURGH AND IN THE RIDGES SUNDAY AFTERNOON
AND OVERNIGHT. GIVEN THE WARM/WET GROUND, ANY ACCUMULATION WILL
BE MINIMAL.
FLOODING POTENTIAL REMAINS HIGHEST ON SATURDAY WITH REPEATED
ROUNDS OF HEAVY RAINFALL ON AN ALREADY SATURATED GROUND. AN
ADDITIONAL 1-2 INCHES IS EXPECTED ACROSS MUCH OF THE AREA FROM
LATE TONIGHT THROUGH SUNDAY, WITH HEAVIEST PERIODS EXPECTED LATE
SATURDAY NIGHT AND EARLY SUNDAY. RISES ARE EXPECTED ON AREA
RIVERS.
LONG TERM /MONDAY THROUGH FRIDAY/
KEY MESSAGES:
- COLDER NEXT WEEK WITH LIGHT RAIN/SNOW CHANCES EARLY WEEK.
- DRY WEATHER BRIEFLY RETURNS MIDWEEK BEFORE ADDITIONAL
PRECIPITATION CHANCES BY LATE WEEK.
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WEAK SURFACE LOW PRESSURE, CROSSING OUT OF THE GREAT LAKES WILL
AID IN STRONG NORTHWESTERLY FLOW BEHIND THE FRONT MONDAY INTO
TUESDAY. THIS COULD BRING A FEW ADDITIONAL SHOWERS TO THE
REGION MONDAY INTO TUESDAY.
UPPER TROUGHING IS EXPECTED TO PERSIST THROUGH MIDWEEK,
RESULTING IN BELOW NORMAL TEMPERATURES. DRY WEATHER LOOKS TO
RETURN BRIEFLY MIDWEEK WITH HIGH PRESSURE BEFORE ADDITIONAL RAIN
CHANCE WITH A SYSTEM LATE WEEK.
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
LARGELY VFR SHOWERS UNDER VFR DECKS HAVE CONTINUED NORTH OF I-70
THIS EVENING. SOUTH OF I-70, PROXIMITY TO A SFC TROUGH AND MORE
ABUNDANT MOISTURE HAS KEPT CIGS BELOW 1000FT. THIS STATUS QUO
IS LARGELY EXPECTED TO HOLD OVERNIGHT UNTIL AFTER 06Z WHEN
FRONTS AND TROUGHS BEGIN TO SURGE NORTH WITH A SFC LOW ADVANCING
THROUGH THE OH VALLEY.
THIS MOVEMENT WILL LIKELY SPARK ANOTHER ROUND OF SHOWERS AND
EMBEDDED THUNDERSTORMS ACROSS THE REGION THROUGH THE REMAINDER
OF THE OVERNIGHT HOURS AND INTO THE MORNING. MODEL UNCERTAINTY
IN EXACT PLACEMENT AND TIMING REMAINS HIGH. THE BEST FORCING
REMAINS CLOSER TO THE LOW AND A LOW-LEVEL JET TO THE NORTH AND
WEST OF PIT. THIS MAKES STORMS FAR LESS OF A CERTAINTY FOR HLG
AND MGW WHERE VCTS HAS BEEN INCLUDED IN THE TAFS.
AS CONVECTIVE ACTIVITY SURGES NORTH CIGS IN THE SOUTH ARE
EXPECTED TO RISE AND MANY MODELS SUPPORT VFR CONDITIONS
ESTABLISHING THEMSELVES IN THE WARM SECTOR BENEATH THE SURGING
WARM FRONT. HOW FAR THIS CLEARING GETS REMAINS A LARGER QUESTION
WITH MODELS SHOWING THE LINE NEAR/JUST SOUTH OF PIT/AGC.
OUTLOOK... THE UPPER OHIO RIVER VALLEY REMAINS POSITIONED
BETWEEN A MOUNTAIN WEST TROUGH AND EAST COAST RIDGE THAT WILL
FOSTER MULTIPLE ROUNDS OF MODERATE TO LOCALLY HEAVY RAIN AND
THUNDERSTORMS THROUGH SUNDAY MORNING. TIMING AND SHAPE OF EACH
PASSING SHORTWAVE TROUGH REMAINS VARIABLE, WHICH CAN ALTER THE
AXIS OF HEAVIEST PRECIPITATION AND LOWEST CLOUDS. CONTINUED
LIMITED WINDOWS OF VFR AND DRY CONDITIONS ARE EXPECTED THROUGH
THE PERIOD AS THE PATTERN CONTINUES TO FAVOR BOUTS OF MVFR/IFR
RESTRICTIONS IN ANY HEAVIER RAIN SHOWERS AND OCCASIONAL
THUNDERSTORMS.
HEAVY RAIN IS LIKELY TO BREAK SUNDAY INTO MONDAY AS AN UPPER-
LEVEL TROUGH IMPINGES UPON THE AREA, SWITCHING US OVER TO A
COOLER PATTERN FEATURING PERIODIC RAIN/SNOW CHANCES. THIS
PATTERN SWITCH LIKELY MEANS A CONTINUED PERIOD OF RESTRICTIONS.
HYDROLOGY
THE POTENTIAL FOR HEAVY RAINFALL WILL EXIST THROUGH SUNDAY. AT
THIS TIME, AREAS ACROSS OHIO HAVE THE POTENTIAL TO SEE THE
HEAVIEST RAINFALL, WHERE A FLOOD WATCH CONTINUES. CURRENT NBM
VALUES INDICATE A 70 PERCENT CHANCE OR GREATER OF AT LEAST 2
INCHES OF RAIN OVER A 72 HR PERIOD IN THIS REGION. LESSER
PROBABILITIES EXIST FURTHER EAST, THOUGH A TREND UP HAS BEEN
NOTED IN THE LATEST ENSEMBLE GUIDANCE AND WILL NEED TO BE
MONITORED FOR ANY POTENTIAL EXPANSION OF THE FLOOD WATCH. THE
EXACT LOCATION OF THE HEAVIEST RAIN WILL DEPEND ON THE POSITION
OF A QUASI-STATIONARY SURFACE FRONT. PRECIPITABLE WATER IS
EXPECTED TO REMAIN ELEVATED THROUGH SUNDAY, WITH SOME PERIODIC
JET ENHANCED ASCENT. EVEN AFTER THE HEAVY RAIN POTENTIAL ENDS,
RIVER LEVELS WILL LIKELY REMAIN ELEVATED FOR A FEW DAYS. CURRENT
ENSEMBLE RIVER FORECAST PROJECTIONS ALSO FOCUS THE MOST
SIGNIFICANT RIVER RISES ACROSS OHIO.
WILL MONITOR FURTHER TRENDS FOR ANY FUTURE ADJUSTMENTS TO THE
WATCH.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH THROUGH SUNDAY MORNING FOR PAZ021-029-031-073>076.
OH...FLOOD WATCH THROUGH SUNDAY MORNING FOR OHZ039-040-048>050-
057>059-068-069.
WV...FLOOD WATCH THROUGH SUNDAY MORNING FOR WVZ001>004-012-021-509-
510.
SYNOPSIS...RACKLEY
NEAR TERM...RACKLEY
SHORT TERM...RACKLEY
LONG TERM...RACKLEY/22
AVIATION...AK
HYDROLOGY...
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