767
FXUS61 KPBZ 091722
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
122 PM EDT TUE AUG 9 2022
SYNOPSIS
SHOWERS AND THUNDERSTORMS CAN BE EXPECTED TODAY AND WEDNESDAY,
MAINLY SOUTH OF PITTSBURGH, WITH THE PASSAGE OF A SLOW MOVING
COLD FRONT. A SECONDARY FRONT ON THURSDAY WILL BRING ISOLATED
SHOWERS, BUT ALSO WILL BRING A DRIER, MORE REFRESHING AIR MASS
THAT WILL REMAIN IN PLACE THROUGH THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/...
THE FRONTAL BOUNDARY HAS DROPPED THROUGH IDI AND PIT AND
CONTINUES A SLOW MARCH SOUTH. SHOWERS AND A FEW THUNDERSTORMS ARE
ALREADY FORMING ALONG AND AHEAD OF THE BOUNDARY AS CAPE
CONTINUES TO BUILD IN AN UNCAPPED COLUMN. THE SEVERE THREAT
CONTINUES TO APPEAR NONEXISTENT WITH WEAK FLOW AND MOIST
SOUNDING PROFILES. HOWEVER, HIGH PWAT, LARGE WARM CLOUD DEPTHS,
AND STORM MOVEMENT PARALLEL TO THE BOUNDARY POINT TO AN AT LEAST
LOCALIZED HEAVY RAIN THREAT AS THE FRONT SLOWLY SINKS SOUTH.
WITHOUT A STRONG SHORTWAVE TO PUSH THE FRONT, THE BOUNDARY
BECOMES QUASI-PARALLEL TO THE MID-LEVEL FLOW AND STALLS OUT
NEAR THE MASON-DIXON LINE BY THIS EVENING, WHICH IS WHERE
LIKELY POPS WILL BE FOCUSED BY 00Z. FLASH FLOOD GUIDANCE VALUES
IN PORTIONS OF THE SOUTHERN CWA ARE BELOW 2 INCHES IN THREE
HOURS, WHICH WILL BE ACHIEVABLE IN LOCATIONS WHERE STORMS TRAIN.
THEREFORE, AFTER COLLABORATION WITH RLX, ELECTED TO HOIST A
FLOOD WATCH FOR THE SOUTHERN CWA FOR POSSIBLE FLASH FLOOD
ISSUES.
COVERAGE OF SHOWERS AND STORMS WILL DIURNALLY DECREASE
DURING THE EVENING, BUT GIVEN THE FRONT AND THE DEEP MOISTURE
AHEAD OF IT, SOME LOW POPS WILL BE MAINTAINED THROUGH THE NIGHT.
A SOMEWHAT COOLER AND DRIER AIR MASS WILL BEGIN TO BUILD IN
OVERNIGHT BEHIND THE BOUNDARY.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
THE FRONT WILL LIKELY CONTINUE TO HANG AROUND THE FAR SOUTHERN
CWA INTO AT LEAST WEDNESDAY AFTERNOON, BEFORE A RELATIVELY WEAK
MID-LEVEL SHORTWAVE GIVES THE BOUNDARY A SOUTHWARD PUSH
BY EVENING. THUS, THE FLOOD WATCH WILL CONTINUE THROUGH THE
DAYLIGHT HOURS AS SHOWERS/STORMS WITH HEAVY RAIN MAY DEVELOP
ONCE AGAIN BEFORE THE FRONT CLEARS THE REGION. AGAIN, THERE IS
VIRTUALLY NO SEVERE THUNDERSTORM THREAT IN THE OVERALL MOIST,
WEAK FLOW PATTERN. RAIN COVERAGE WILL AGAIN DROP OFF WEDNESDAY
EVENING WITH THE LOSS OF HEATING, AND THE DRIER AIR MASS WILL
CONTINUE TO MAKE INCREMENTAL OVERNIGHT PROGRESS.
THE FRONT WILL HAVE FINALLY EXITED THE REGION BY THURSDAY MORNING.
HOWEVER, A MORE SIGNIFICANT SHORTWAVE TROUGH WILL DROP DOWN FROM THE
GREAT LAKES, QUICKLY PUSHING A SECONDARY COLD FRONT INTO THE CWA.
INSTABILITY WILL BE SUFFICIENT FOR SHOWERS AND A FEW THUNDERSTORMS,
BUT OVERALL LIMITED MOISTURE SHOULD KEEP COVERAGE SCATTERED WITH THE
BOUNDARY. A MOSTLY PLEASANT NIGHT IS IN STORE FOR THURSDAY NIGHT AS
THE SKY CLEARS AND AS DEWPOINTS DROP INTO THE 50S.
LONG TERM /FRIDAY THROUGH MONDAY/
THE EXTENDED PERIOD WILL FEATURE TEMPERATURES WHICH WILL AVERAGE OUT
NEAR TO BELOW CLIMATOLOGY INTO EARLY NEXT WEEK. SURFACE HIGH
PRESSURE WILL PROVIDE DRY WEATHER FOR FRIDAY AND SATURDAY AS A
SHORTWAVE TROUGH MOVES EAST OF THE REGION. THE VARIOUS
MODELS/ENSEMBLES SHOW SOME SHORTWAVE ENERGY REINFORCING A NORTHEAST
CONUS TROUGH STARTING ON SUNDAY, WHICH WILL BRING BACK CHANCES OF
ISOLATED TO SCATTERED SHOWERS SUNDAY INTO TUESDAY.
AVIATION /17Z TUESDAY THROUGH SATURDAY/
SCATTERED SHOWERS WITH AN ISOLATED THUNDERSTORM ARE POSSIBLE
AHEAD A SLOW MOVING COLD FRONT THAT WILL STALL SOUTH OF
PITTSBURGH THIS EVENING. ISOLATED SHOWERS WILL POSSIBLE AROUND
MGW THROUGH WEDNESDAY MORNING BEFORE THE UPPER TROUGH COMPLETES
ITS PASSAGE LATER IN THE DAY.
MOISTURE CONVERGENCE AROUND THE BOUNDARY WILL GENERALLY PROMOTE
MVFR/IFR CONDITIONS THROUGH THE PERIOD, THOUGH LOW VFR CIGS ARE
EXPECTED BY THE LATE AFTN WITH HEATING (OR SUBSIDENCE FOR
LOCALES NORTH OF THE FRONT). THE LACK OF DRY AIR AT THE SFC WILL
FOSTER FOG DEVELOPMENT, WITH INTENSITY DICTATED BY THE DEGREE OF
OVERNIGHT CLEARING, WHICH WILL FAVOR NORTHERN TERMINALS.
OUTLOOK
VFR CONDITIONS WILL RETURN TO MOST TERMINALS WEDNESDAY AFTN/EVE
AS THE FRONT FINISHES ITS SOUTHERN PUSH, DRAGGING REMNANT STORMS
WITH IT. ANOTHER COLD FRONT WILL SWEEP THROUGH THURSDAY WITH
ADDITIONAL AREAWIDE PRECIP CHANCES BEFORE A PROLONGED VFR PERIOD
VFR RETURNS UNDER HIGH PRESSURE.
PBZ WATCHES/WARNINGS/ADVISORIES
PA...FLOOD WATCH THROUGH WEDNESDAY EVENING FOR PAZ031-075-076.
OH...FLOOD WATCH THROUGH WEDNESDAY EVENING FOR OHZ068-069.
WV...FLOOD WATCH THROUGH WEDNESDAY EVENING FOR WVZ004-012-021-
509>512.
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