712
FXUS61 KPBZ 221214 AAB
AFDPBZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
814 AM EDT THU AUG 22 2019
SYNOPSIS
SHOWERS AND STORMS ARE EXPECTED THIS AFTERNOON WITH THE PASSING OF A
COLD FRONT. COOLER, DRIER AIR WILL THEN RETURN FOR THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/
8AM UPDATE...INCREASE MORNING POP ACROSS SOUTHEAST OH AS AN
OVERNIGHT STORM COMPLEX HAS MAINTAINED ENOUGH STRENGTH/ORGANIZATION
TO INCREASE THE LIKELIHOOD OF RAIN IN THE AREA THIS MORNING. NO OTHER
NOTABLE CHANGES MADE, THOUGH CONFIDENCE IS LOW ON THE EFFECTS THIS
COMPLEX WILL HAVE ON THE ANTICIPATED STORM DEVELOPMENT THIS AFTERNOON
WITH THE COLD FRONT.
PREVIOUS DISCUSSION...
A WEAK SHORTWAVE, EMBEDDED IN A BROAD UPPER-LEVEL TROUGH, IS
PROVIDING ENOUGH FORCING WITH JUST ENOUGH INSTABILITY TO ALLOW
SHOWERS TO PERSIST THROUGH CENTRAL OH THIS MORNING. AN MORE STABLE
ENVIRONMENT ACROSS EASTERN OH/WESTERN PA SHOULD CAUSE THESE STORMS TO
DISSIPATE THIS MORNING, BUT UNCERTAIN HAVE FAR IT WILL PROGRESS EAST
BEFORE TAPERING OFF. TO THE NORTH, A SWATH OF LIGHTER RAIN SHOWERS
WILL CONTINUE TO TRAVERSE EAST ALONG THE COLD FRONTAL BOUNDARY THIS
MORNING.
A MORE PROMISING UPPER-LEVEL SHORTWAVE WILL HELP ADVECT DEEPER
MOISTURE INTO THE REGION BY THIS AFTERNOON, WITH PWAT VALUES AROUND 1
SD ABOVE NORMAL. AS THE TROUGH DEEPENS, THE SURFACE COLD FRONT WILL
SAG SOUTH OUT OF LAKE ERIE, HELPING PROVIDE LIFT FOR STORM
INITIATION. THE COMBINATION OF HIGH MOISTURE CONTENT, WESTERLY FLOW
ALOFT, AND AN WEST-EAST ORIENTED FRONT, THERE IS INCREASED POTENTIAL
FOR FLASH FLOODING DUE TO TRAINING OF STORMS THAT PRODUCE HIGHER
RAINFALL RATES. HOWEVER, THE LACK OF STRONGER INSTABILITY DUE TO
CLOUD COVER FROM MORNING CONVECTION WILL MUTE THE THREAT ENOUGH TO
PRECLUDE WATCH ISSUANCE. AT THE MOMENT, AREAS ALONG AND SOUTH OF I-70
WILL HAVE THE BEST CHANCES FOR THE HEAVIEST ACCUMULATIONS DUE TO THE
EXPECTED GREATER INSTABILITY IN THE REGION.
THE COLD FRONT SHOULD COMPLETE ITS PASSAGE BY LATE THURSDAY NIGHT FOR
AREAS NORTH OF I-70.
SHORT TERM /FRIDAY/
A FEW STRAY SHOWERS MAY LINGER IN NORTHERN WV/WESTERN MARYLAND EARLY
FRIDAY MORNING AS THE FRONTAL BOUNDARY EXITS TO THE SOUTHEAST.
TEMPERATURES ARE EXPECTED TO BE NEAR OR JUST BELOW THE CLIMATOLOGICAL
AVERAGE, WITH HIGHS IN THE 70S ON FRIDAY. DEW POINTS TOO ARE
EXPECTED TO DROP INTO THE LOW-50S, UPPER-40S NEAR I-80, AND BRING
COMFORTABLE CONDITIONS.
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
SURFACE HIGH PRESSURE AND NORTHWEST FLOW ALOFT IS ANTICIPATED TO
BRING DRY AND COMFORTABLE WEATHER THROUGHOUT THE WEEKEND.
RETURN, SOUTHWESTERLY FLOW ALOFT ASSOCIATED WITH A DEEPENING CENTRAL
PLAINS TROUGH IS EXPECTED TO SUPPORT AN INCREASE IN BOTH TEMPERATURE
AND MOISTURE BY EARLY NEXT WEEK, WITH HIGH TEMPERATURE REBOUNDING TO
NEAR CLIMATOLOGICAL NORMALS. PRECIPITATION CHANCES WILL BE LARGELY
DETERMINED BY SHORTWAVE ACTIVITY TRAVERSING THROUGH THE BASE OF THE
TROUGH THROUGH MID-WEEK.
AVIATION /12Z THURSDAY THROUGH MONDAY/
AN UPPER LEVEL SHORTWAVE PLUS A SFC COLD FRONT WILL MOVE SLOWLY
THROUGH THE REGION TODAY, BRING SHOWERS/TSTMS TO MOST SITES.
RESTRICTIONS ARE LIKELY WITH ANY STORMS IN ADDITION TO LOWERED CIGS
BEFORE/JUST BEHIND THE COLD FRONTAL PASSAGE. SHOWERS/STORMS WILL
END SHORTLY AFTER THE FRONTAL PASSAGE, WITH THE FRONT EXPECTED TO
STOP SOMEWHERE SOUTH OF I-70.
MOST AREAS WILL REMAIN DRY/VFR OVERNIGHT BEHIND THE FRONT, THOUGH A
PERIOD OF LOW STRATUS/FOG COULD DEVELOP IF ENOUGH CLOUDS CLEAR AND
DRY AIR IS SLOWER TO MOVE IN. AROUND AND SOUTH OF THE STALLED FRONT,
MVFR/IFR RESTRICTIONS WILL BE MORE LIKELY WITH OCCASIONAL WAVES OF
SHOWERS DUE TO PASSING WEAK DISTURBANCES THROUGH FRIDAY MORNING.
THERE REMAINS UNCERTAINTY IN THE TIMING/PROGRESSION OF THE FRONT,
THE AMOUNT OF INSTABILITY AVAILABLE FOR STORM GENERATION, AND THE
DEGREE OF CLEARING BEHIND THE FRONT AS MODELS CONTINUE TO STRUGGLE
WITH THESE DETAILS. IT IS FURTHER COMPLICATED BY THE PRESENCE OF
CONVECTION THAT MOVED THROUGH OH THIS MORNING AND ITS IMPACTS ON THE
ENVIRONMENT.
OUTLOOK
VFR CONDITIONS WILL RETURN FOR ALL LOCATIONS BY FRIDAY AFTERNOON
THROUGH THE WEEKEND.
PBZ WATCHES/WARNINGS/ADVISORIES
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page