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Area Forecast Discussion
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000
FXUS61 KPBZ 210523 AAC
AFDPBZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
123 AM EDT SUN SEP 21 2014

.SYNOPSIS...
A COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS TODAY. HIGH
PRESSURE WILL DOMINATE THE REMAINDER OF THE WEEK WITH DRY WEATHER.

&&

.NEAR TERM /THROUGH TODAY/...
FOR THE OVERNIGHT...MINOR ADJUSTMENTS USING LATEST MODEL DATA.
MODELS ARE CONSISTENT IN SHOWING THE ACTIVITY OVERNIGHT WEAKENING
AS IT ENCOUNTERS A STABLE ATMOSPHERE AND THE SHORTWAVE TROUGH
LINKED TO THE ACTIVITY WEAKENS AS WELL.

STILL CONCERNED WITH THE POTENTIAL FOR STRONG TO SEVERE STORMS
LATE TODAY WITH THE PASSAGE OF A COLD FRONT. WIND FIELD IS
IMPRESSIVE AND THE ATMOSPHERE DESTABILIZES AHEAD OF THE BOUNDARY.
NAM IS CLEARLY THE STRONGEST WITH MESOSCALE FEATURES COMPARED TO
OTHER OPERATIONAL MODELS. THIS LEADS ME TO BELIEVE THAT THE NAM
MAY BE ON ITS OWN WITH ITS DEPICTION OF THE SITUATION SO WILL LEAN
AWAY FROM IT. ANY CONVECTION THIS AFTERNOON WILL HAVE THE
POTENTIAL TO PRODUCE GUSTY WINDS. WITH MIXING HEIGHTS RISING AHEAD
OF THE FRONT...COULD STILL SEE STRONGER WIND GUSTS WITHOUT
CONVECTION. OTHER LIMITING FACTORS WILL BE CLOUD COVER AND THE
RISK FOR SCATTERED SHOWERS THIS MORNING. FOR A NAM SOLUTION TO
COME TO FRUITION...WOULD NEED TO SEE CONVECTION FIRE AND GROW OVER
THE GREAT LAKES ALONG THE FRONT AND THEN SUSTAIN ITSELF...THANKS
TO THE HIGH SHEAR VALUES IN ITS SOLUTION. THE OTHER OPERATIONAL
MODELS ARE NOT IN TOTAL AGREEMENT WITH THIS SCENARIO. FORECAST
WILL SHOW SHOWERS THIS MORNING AND THEN SHOWERS/STORMS THIS
AFTERNOON RIGHT ALONG THE FRONT. HAVE INCREASED WIND GUSTS DURING
THE AFTERNOON.

FRONT WILL PICK UP SPEED LATE THIS AFTERNOON AS STRONG SHORTWAVE
TROUGH WILL DIG DOWN FROM THE WESTERN GREAT LAKES.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
SHOWER/STORM CHANCES WITH THE FRONT WILL END IN THE EVENING OVER
THE SOUTH. STRONG CAA WILL FOLLOW ON THE HEELS OF THE BOUNDARY AS
THE TROUGH AXIS MOVE THROUGH LATE SUNDAY NIGHT. 85H TEMPS WILL
DROP SOME 6-8 DEGREES SUNDAY NIGHT AS THE FLOW VEERS TO THE
NORTHWEST. EXPECT A LARGE AREA OF STRTOCU TO QUICKLY COVER THE
REGION. ITS POSSIBLE...WITH THE COLDER AIR AND NORTHWEST FLOW...
SHOWERS COULD REDEVELOP...PARTICULARLY OVER THE NORTH AND RIDGES.

HEART OF THE COLD AIR SETTLES IN OVER THE REGION MONDAY. EXPECT
THE STRATOCU DECK TO REMAIN IN PLACE. LATEST FORECAST SOUNDINGS
ARE SHOWING A THIN LAYER OF SATURATION WHICH WOULD LIKELY PREVENT
ADDITIONAL SHOWER ACTIVITY ON MONDAY. NOTICEABLY COLDER 85H TEMP
FORECAST MONDAY COMPARED TO PREVIOUS RUNS. THIS WILL NECESSITATE
THE LOWERING OF TEMPS ON MONDAY. IF LATEST MODEL OUTPUT IS
CORRECT...HIGHS MONDAY COULD BE 15 TO 20 DEGREES BELOW NORMAL.

COLD AIR WILL QUICKLY RETREAT TO THE NORTHEAST MONDAY NIGHT AS THE
ENTIRE UPPER LEVEL SYSTEM SHIFTS TOWARD THE EAST COAST.

WAA WILL KICK IN MONDAY NIGHT ALLOWING SKIES TO CLEAR.

SURFACE HIGH AND RIDGING ALOFT WILL PROVIDE A SUNNY AND COMFORTABLE
DAY TUESDAY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
DRY AND SEASONABLE PATTERN EXPECTED FOR THE LONG TERM. 

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
GRADUAL CONDITION DETERIORATION TO MVFR/LCL IFR CAN BE EXPECTED
LATE TNGT AND INTO SUNDAY AS A CDFNT APCHS FM THE W. ST DVLPMNT IN
THE WARM...MOIST FLOW UNDR THE INVERSION IS ANTICIPATED AS IS
ELEVATED SHWR DVLPMNT TWD MRNG. THE BTR CHC FOR IFR IS EXPECTED IN
THE MORE WIDESPREAD SHWRS AFTR DAYBREAK.

OUTLOOK.../SUNDAY NGT THROUGH THURSDAY/...
COLD ADVCTN OFF THE GREAT LAKES IS EXPECTED TO SPPRT MVFR STRATOCU
THRU MONDAY. THEREAFTER...GENL VFR IS ONLY EXPECTED TO BE
TARNISHED BY PERIDAWN FOG AND LCL ST.

&&

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

&&

$$






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