Area Forecast Discussion
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FXUS61 KPBZ 270751
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
351 AM EDT WED MAY 27 2015

.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL PERSIST TODAY...WITH INCREASING
SHOWER AND THUNDERSTORM CHANCES TONIGHT. DRIER WEATHER IS EXPECTED
THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
SHORTWAVE CONTINUES TO LIFT ACROSS THE AREA DURING THE PREDAWN
HOURS. THUNDER HAS ALL BUT CEASED WITH THE LOSS OF INSTABILITY.
EASTWARD COMPONENT OF MOTION IS SLOW...SO STILL EXPECT RAIN TO
LINGER ALONG THE RIDGES PAST SUNRISE. THE EXIT OF THE SHORTWAVE
WILL THEN ALLOW FOR A RELATIVE LULL IN ACTIVITY FROM LATE MORNING
INTO THE AFTERNOON...ALTHOUGH KEPT A LOW CHANCE ALONG THE RIDGES
AS A WEAK LOBE OF VORTICITY LINGERS. ALTHOUGH SOME INSTABILITY
BUILDS DURING THE AFTERNOON...THE LACK OF A TRIGGER SUGGESTS
WIDELY SCATTERED AFTERNOON CONVECTION AT BEST WEST OF THE RIDGES.

A MORE POTENT SHORTWAVE WILL ARRIVE IN MICHIGAN LATER TODAY...AND
THEN BEGIN TO SHEAR OUT AS IT CROSSES THE EASTERN GREAT LAKES
TONIGHT. ACCOMPANYING SURFACE BOUNDARY WILL LIKEWISE BE FADING AS
IT APPROACHES. HAVE SKIMMED LIKELY POPS ALONG THE NORTHWEST
FRINGE OF CWA...CLOSER TO SHORTWAVE. SPC HAS ANOTHER SLIGHT RISK
OF SEVERE STORMS IN THIS AREA. EXPECT SOMETHING SIMILAR TO
YESTERDAY. WHILE BEST SHEAR AND INSTABILITY LIE TO THE
WEST...BUFKIT SOUNDINGS AT LOCATIONS LIKE ZZV AND PHD SUGGEST THAT
AROUND 1000 J/KG OF CAPE MAY COMBINE WITH 30-40 KNOTS OF MIDLEVEL
FLOW...ALLOWING FOR A FEW STORMS WITH STRONG TO DAMAGING WIND
GUSTS. LESSER RISK TO THE EAST...WHERE CHANCE POPS ARE MAINTAINED
WITH LESS POTENTIAL LIFT. ACTIVITY WILL BEGIN TO QUICKLY DIE DOWN
AFTER 06Z WITH LOSS OF SUPPORT FROM EXITING SHORTWAVE.

GOING TEMPERATURES WERE VERY CLOSE TO A GUIDANCE CONSENSUS...AND
ONLY MADE MINOR TWEAKS.  CL

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
UPPER-LEVEL WAVE PASSES EAST OF THE AREA THURSDAY MORNING WITH
BRIEF RIDGING ALOFT RESULTING IN A DRYING TREND FOR THE LATTER
PART OF THE WEEK. THE AXIS OF THE UPPER RIDGE MOVES EAST BY MIDDAY
FRIDAY ALLOWING DEEP SOUTHWESTERLY FLOW TO KICK IN. THIS...AND
INCREASED SUNSHINE WILL FUEL TEMPERATURES PUSHING WELL INTO THE
80S...AT LEAST 10 DEGREES HIGHER THAN NORMAL.

THE DRY WEATHER FADES AWAY QUICKLY HEADING INTO THE WEEKEND AS THE
NEXT LOW PRESSURE SYSTEM MOVES INTO THE GREAT LAKES REGION. AS THE
FRONT APPROACHES...SOUTHERLY MOISTURE WILL FEED SATURDAY AFTERNOON
SHOWER AND THUNDERSTORM CHANCES. TEMPERATURES SATURDAY WILL STILL BE
WELL ABOVE NORMAL...BUT THE INCREASED CLOUD COVER ASSOCIATED WITH
THE APPROACHING SYSTEM MAY KEEP HIGHS A FEW DEGREES LOWER THAN
FRIDAYS MARKS.  TAX

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
FRONTAL BOUNDARY CLEARS A MAJORITY OF THE FORECAST AREA LATE
SATURDAY NIGHT...BUT MEETS RESISTANCE CROSSING THE APPALACHIANS.
WITH SOME TIMING DIFFERENCES ACROSS LONG-RANGE MODELS...DECIDED TO
TAKE THE SLOWER FRONTAL PROGRESSION...ULTIMATELY LINGERING RAIN
CHANCES IN THE HIGHER TERRAIN SUNDAY AFTERNOON. ELSEWHERE...SOME
RELIEF FROM THE WELL ABOVE NORMAL TEMPERATURES WILL COME SUNDAY INTO
MONDAY AS A DRY HIGH PRESSURE SYSTEM BUILDS TO THE NORTH. HEADING
INTO NEXT WEEK...LONG-RANGE GUIDANCE HAD MAJOR DIFFERENCES WITH THE
RETURN OF SOUTHERLY MOISTURE ON THE BACKSIDE OF THE HIGH. THE LATEST
00Z GFS HAS COME INTO BETTER AGREEMENT WITH ITS ECMWF AND GFS
ENSEMBLE BRETHREN...KEEPING THE RETURN OF MOISTURE SUPPRESSED
THROUGH THE EARLY PART OF THE WEEK. HAVE LOWERED MONDAY AND TUESDAY
POPS TO REFLECT THIS. AS THE HIGH PUSHES OFF THE COAST TOWARDS THE
MIDDLE OF NEXT WEEK THE ENHANCED SOUTHERLY FLOW WILL ONCE AGAIN
BRING WARM AND WET BACK INTO THE FORECAST.  TAX

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
SHORTWAVE MOVING ACROSS CURRENTLY...WITH MVFR/IFR VISIBILITIES IN
SHRA AND DYING TSRA. THESE WILL PULL ACROSS THE RIDGES TOWARDS
SUNRISE. BEHIND THE RAIN...SOME MVFR/IFR CIGS AND VIS ARE EXPECTED
WITH FOG. LOW CLOUDS WILL LIFT INTO A VFR CU DECK BY MIDDAY. ANY
DAYTIME SHRA/TSRA SHOULD BE QUITE SPOTTY AND DID NOT INCLUDE IN
TAF AT THIS TIME. NEXT SHORTWAVE ARRIVES AFTER 00Z...WITH MORE
RAIN ARRIVING FROM WEST TO EAST. KEPT VFR FOR NOW BUT BRIEF
RESTRICTIONS ARE AGAIN POSSIBLE IN SHRA/TSRA.

.OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
OVERALL IMPROVEMENT IS INDICATED AS PRECIP CHANCES DECLINE
THROUGH FRIDAY. HOWEVER...PRECIP...AND RESTRICTION CHANCES WILL
AGAIN INCREASE WITH AN ENCROACHING FRONTAL SYSTEM THIS WEEKEND.

&&

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

&&

$$



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