Area Forecast Discussion
Issued by NWS

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FXUS61 KPBZ 260742
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
342 AM EDT TUE MAY 26 2015

.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL PERSIST THROUGH THE SHORTENED WORK
WEEK...WITH SHOWER AND THUNDERSTORM CHANCES EACH DAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
FIRST IN A SERIES OF SHORTWAVES IS CURRENTLY RIDING NORTHEASTWARD
ACROSS THE AREA WITH SOME SHRA. NO THUNDER SO FAR AS WARM AIR
ALOFT IS KEEPING INSTABILITY IN CHECK. EXPECT THIS ACTIVITY TO
CONTINUE TO LIFT NORTHWARD THIS MORNING...WITH A LULL IN ACTIVITY
DURING THE LATE MORNING HOURS.

DAYTIME HEATING WILL HELP TO INCREASE CAPE DURING THE AFTERNOON
HOURS...BUT A TRIGGER WILL BE LACKING THROUGH MIDAFTERNOON AND
THUS WILL KEEP POPS AT THE LOWER END OF CHANCE. THIS WILL CHANGE
TOWARD THE END OF THE DAY AS A MORE POTENT SHORTWAVE TROUGH
APPROACHES FROM THE SOUTHWEST. HAVE LIKELY POPS SPREADING ACROSS
THE REGION THROUGH TONIGHT AS A RESULT.

SPC HAS A SLIGHT RISK OF SEVERE THUNDERSTORMS UP OVER MOST OF
OHIO. THINK THAT BETTER MIDLEVEL FLOW AND INSTABILITY WILL BE
REALIZED TO THE SOUTH AND WEST OF OUR CWA DURING THE
AFTERNOON/EVENING...TOWARDS THE MIDDLE AND LOWER OHIO VALLEY.
HOWEVER STORMS THAT DEVELOP COULD PROPAGATE TOWARDS THE WV/OH
BORDER LATE TODAY WITH SOME STRONG AND POTENTIALLY DAMAGING WIND
GUSTS. WILL MENTION POTENTIAL IN HWO BUT DO NOT FORESEE A
SIGNIFICANT SEVERE OUTBREAK. STORMS HAVE THE POTENTIAL TO BE
EFFICIENT RAIN PRODUCERS AS WELL. PWATS IN THE 1.5 TO 1.75 RANGE
ARE NEAR THE HIGH END OF CLIMATOLOGY...AND WARM CLOUD DEPTHS WILL
LIKELY EXCEED 10K FEET TONIGHT. IT DOES APPEAR THAT STORMS WILL
MOVE WITH SUFFICIENT SPEED TO DETER EXCESSIVE RAINFALL FOR THE
MOST PART...BUT POOR DRAINAGE LOCATIONS MAY NEED TO BE WATCHED.

TEMPERATURES WERE MAINLY TWEAKED DOWNWARD SLIGHTLY TODAY TO GET
MORE IN LINE WITH MODEL CONSENSUS. LITTLE CHANGE NEEDED FOR
TONIGHT.  CL

&&

.SHORT TERM /WEDNESDAY THROUGH SATURDAY/...
THE FIRST HALF OF THE PERIOD WILL CONSIST OF UNSETTLED WEATHER AS
AN UPPER LEVEL SHORTWAVE TROUGH IS PROGGED TO BE OVER THE GREAT
LAKES AND SHIFT EASTWARD. DEEP MOISTURE WILL BE MAINTAINED OVER
THE REGION ALLOWED BY SOUTHWEST FLOW. THEREFORE...CHANCE TO LIKELY
POPS WERE MAINTAINED AND ADJUSTED SLIGHTLY BASED ON LATEST
GUIDANCE.

A LULL IN PRECIPITATION CAN BE EXPECTED LATE THURSDAY INTO FRIDAY
AS BRIEF HIGH PRESSURE BUILDS UNDER A WEAK RIDGE IN THE WAKE OF
THE SHORTWAVE TROUGH.

PRECIPITATION CHANCES RISE AGAIN ON SATURDAY SUPPORTED BY AN
APPROACHING SURFACE BOUNDARY AND A WEAK SPLIT FLOW ALOFT. THE FRONT
IS EXPECTED TO SLOWLY SAG ACROSS THE FORECAST AREA THROUGH SATURDAY
AS PREDICTED BY ECMWF AND GFS SOLUTIONS.

FORECASTED TEMPERATURES WILL BE ABOVE NORMAL THROUGH THE PERIOD.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
VARIOUS LONG RANGE SOLUTIONS AGREE ON STUBBORN BOUNDARY LAID
ACROSS THE FORECAST AREA THROUGH THE WEEKEND. THEREFORE CHANCE
POPS WERE PRESERVED WITH THE SUPPORT OF A SERIES OF UPPER LEVEL
DISTURBANCES ACROSS THE UPPER OHIO VALLEY. GFS AND ECMWF DIFFER
OVER THE OUTCOME OF AN APPROACHING TROUGH FROM THE MIDWEST IN
TERMS OF MAGNITUDE...POSITION...AND TIMING. THEREFORE PERSISTENCE
WAS HEAVILY USED IN THE LATTER HALF OF THE PERIOD AND LOW CHANCE
POPS WERE INTRODUCED.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
VFR IS FORECAST IN THE MEAN OVER THE NEXT 24 HOURS...BUT THERE
WILL BE OPPORTUNTIES FOR BRIEF RESTRICTIONS. MOIST SOUTHWEST FLOW
WILL ALLOW FOR SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE
PERIOD...MOST NUMEROUS DURING THE AFTERNOON AND EVENING HOURS.
WITH UNCERTAIN TIMING...HAVE ELECTED TO CONTINUE WITH VCSH/VCTS
FOR THE BULK OF THE TAF PERIOD. BRIEF DROPS TO MVFR AND EVEN IFR
CIG/VSBY WILL BE POSSIBLE IN ANY SHOWER OR STORM...BUT DID NOT
WANT TO INCLUDE LONG TEMPO PERIODS. EXPECT COVERAGE TO WANE PAST
SUNSET AS INSTABILITY DROPS. WINDS WILL GENERALLY BE AROUND 10
KNOTS OR LESS OUT OF THE SOUTH AND SOUTHWEST.  CL

.OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/...
ABUNDANT MOISTURE AND DISTURBANCES IN SOUTHWEST FLOW ARE LIKELY
TO SPAWN PERIODIC RESTRICTIONS THROUGH WEDNESDAY.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$


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