Area Forecast Discussion
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000
FXUS61 KPBZ 061144
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
744 AM EDT WED MAY 6 2015

.SYNOPSIS...
SCATTERED SHOWERS TODAY WILL GIVE WAY TO A DRIER MID-WEEK WITH
ABOVE AVERAGE TEMPERATURES.

&&

.NEAR TERM /THROUGH THURSDAY/...
SHOWER ACTIVITY REMAINS CONFINED TO NORTH OF I-80 AS THE REMNANTS
OF THE SURFACE BOUNDARY CONTINUES TO DISSIPATE. MID-LEVEL FLOW
IS FROM ALMOST DUE-WEST...SO THE A PUSH SOUTHWARD IS NOT EXPECTED.

CURRENT IR SATELLITE SHOWING AN EXPANSIVE SECTION OF CLEARING
THROUGH THE UPPER OHIO VALLEY. THIS IS A RESULT OF DRIER AIR
PUSHING NORTHWARD AS WHAT IS LEFT OF THE BOUNDARY RETREATS NORTH.
FOG HAS SPORADICALLY DEVELOPED ACROSS THE FORECAST AREA...AND IS
FAIRLY TRANSIENT AT THIS HOUR. WHILE VERY DENSE IN SOME
LOCATIONS...THE FOG HAS BEEN PATCHY ENOUGH THAT AN ADVISORY WAS
NOT WARRANTED. HOWEVER...AN SPS WAS ISSUED FOR DENSE FOG IMPACTING
THE MORNING COMMUTE AROUND THE PITTSBURGH METRO WHERE FOG HAS BEEN
MORE PREVALENT.

THE LAST OF THE REMAINING DEEP MOISTURE WILL SKIRT THE
NORTHEASTERN PERIPHERY OF THE FORECAST AREA WEDNESDAY.
CONSIDERABLE WARMING OF THE LOW-LEVELS WILL ENHANCE LOW-LEVEL
LAPSE RATES AND FEED INSTABILITY TO THE POINT OF THUNDERSTORM
DEVELOPMENT. WITH MOISTURE RETREATING AND ONLY MEAGER FORCING
COMING IN THE FORM OF A WEAK MID-LEVEL WAVE...SHOWER AND
THUNDERSTORM DEVELOPMENT SHOULD BE LIMITED SPATIALLY.

THE AXIS OF THE RIDGE BUILDS IN THROUGH THURSDAY...RESULTING IN A
MUCH DRIER FORECAST AND HIGH TEMPERATURES REACHING WELL ABOVE
NORMAL.
TAX

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
A RELATIVE MAXIMA IN HEIGHTS WILL BECOME RESIDENT OVER THE AREA BY
THE END OF THE WEEK...AS HEIGHTS IN THE INTERMOUNTAIN WEST AND OFF
THE SOUTHEAST COAST BOTH DECLINE. THIS SQUEEZES THE AREA INTO A
FAIRLY TIGHT CORRIDOR OF RIDGING...YET DUE TO THE SLUGGISHNESS OF
ACTIVITY OFF THE SOUTHEAST COAST WITH REGARD TO MOVEMENT...AS WELL
AS THE FACT THAT THERE IS LITTLE IMPETUS FOR ACTIVITY IN THE
INTERMOUNTAIN WEST TO BE EJECTED EASTWARD...IT WOULD SEEM WE
SHOULD REMAIN IN THIS MICRO-RIDGE FOR QUITE A PERIOD.

WHILE THE AIR MASS UNDER THE RIDGE WILL BE SOMEWHAT
UNSTABLE...OWING TO THE LOW LEVEL MOISTURE WE HAVE ALREADY GAINED
THIS WEEK FROM RAINFALL...AND CONTINUE TO WARM AGGRESSIVELY WITH
DECENT INSOLATION AND SOUTHWESTERLY POSITIVE THETA-E ADVECTION...A
LACK OF FORCING MECHANISMS AND SHEAR SHOULD PRECLUDE MUCH IN THE
WAY OF CONVECTIVE DEVELOPMENT THROUGH MUCH OF THE SHORT TERM. SOME
SLIGHT CHANCE POPS WERE INCLUDED FOR DIURNAL
SHOWERS/STORMS...HOWEVER ACTIVITY SHOULD BE FAIRLY ISOLATED.

THE BIG STORY IN THE SHORT TERM WILL BE THE UPWARD RIDE OF THE
TEMPERATURE TRAIN. AS CONSENSUS 500 MB HEIGHTS RISE INTO THE MID
580S...AND 850 MB TEMPERATURES SURPASS 16C...IT WOULD SEEM THAT
MID 80S LOOK TO BECOME INCREASINGLY LIKELY BY LATE IN THE WEEK. IT
WOULD SEEM THE AIR CONDITIONERS MAY GET A PRETTY QUICK START OWING
TO DEWPOINTS LIKELY TO BE IN THE LOWER 60S BY THAT TIME AS WELL.
FRIES

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
RIDGING REMAINS THE LARGE PLAYER IN THE FORECAST RIGHT THROUGH
MONDAY. INCREASING MIXING AND SLIGHTLY HIGHER 850 MB TEMPERATURES
SHOULD OFFSET SLIGHTLY LOWER HEIGHTS BY MONDAY AS THE THE SYSTEM
THAT WILL FINALLY BREAK DOWN THE RIDGE STARTS TO MOVE INTO THE
GREAT LAKES. 00Z GUIDANCE HAS INDICATED A FAIRLY MARKED SLOWING OF
THE EASTWARD PROGRESSION OF THIS SYSTEM RELATIVE TO EARLIER
GUIDANCE...IN LARGE PART DUE TO THE CANADIAN/GFS/GEFS MEMBERS
MAINTAINING A DEEPER UPPER REFLECTION OF THE SYSTEM AS IT EMERGES
INTO THE UPPER MISSISSIPPI VALLEY. THE ECMWF IS FASTER AND FLATTER
WITH THE SYSTEM.

POPS IN THE FORECAST AS WELL AS TEMPERATURE EXPECTATIONS WERE
ADJUSTED FOR A BIT SLOWER ARRIVAL OF THE SYSTEM LIKELY CENTERED
AROUND MONDAY NIGHT. HOWEVER...ONCE THE SYSTEM ARRIVES...THE
CONSENSUS IS STRONG THAT DRYING SHOULD BE FAIRLY AGGRESSIVE BEHIND
IT. LIKEWISE...MUCH COLDER AIR IS EVIDENT ON THE CONSENSUS IN ITS
WAKE. TEMPERATURE EXPECTATIONS WERE ADJUSTED ABRUPTLY DOWNWARD
BEYOND TUESDAY TO ACCOUNT FOR THIS. FRIES

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
BULK OF SHOWER ACTIVITY THIS MORNING MAINLY FROM KFKL TO KDUJ AND
WILL SHIFT EAST TOWARD 14Z.

IFR TO LIFR FOG AT NUMEROUS PORTS WILL SLOWLY IMPROVE TOWARD 14Z.

LATER TODAY...SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED
CLOSER TO THE RIDGES...POSSIBLY NEAR KDUJ AND KLBE. WHILE SPATIAL
COVERAGE IS EXPECTED TO BE LIMITED...DUJ/LBE COULD SEE TEMPORARY
RESTRICTIONS LATE THIS AFTERNOON.

TONIGHT...CLEAR AND CALM CONDITIONS LOOK TO BRING IFR FOG TO SOME
PORTS.

.OUTLOOK.../THURSDAY THROUGH SUNDAY/...
RESTRICTIONS IN FOG CANNOT BE RULED OUT AGAIN FRIDAY MORNING.
SCATTERED SHOWERS AND POSSIBLE RESTRICTIONS FOR SATURDAY AND
SUNDAY.

&&

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

&&

$$



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