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000
FXUS61 KCTP 240025
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
825 PM EDT THU MAY 23 2013

.SYNOPSIS...
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A COLD FRONT WILL CROSS COMMONWEALTH TONIGHT AND EARLY FRIDAY.
AN UPPER LOW WILL TRAVERSE THE REGION ON FRIDAY...PROVIDING
COOL...SHOWERY...ALMOST BLUSTERY CONDITIONS. CANADIAN HIGH
PRESSURE WILL BUILD OVER PENNSYLVANIA FROM THE GREAT LAKES AND
BRING IMPROVING AND DRIER WEATHER THROUGH THE MEMORIAL DAY
WEEKEND. TEMPERATURES WILL TREND COLDER OVER THE NEXT FEW
DAYS...BEFORE MODERATING THROUGH THE EARLY TO MIDDLE PART OF NEXT
WEEK.
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&&

.NEAR TERM /UNTIL 7 AM FRIDAY MORNING/...
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SHOWERS GREW INTO TSRA FOR MUCH OF THE AREA LATE THIS AFTN...BUT
IT HAS QUIETED DOWN CONSIDERABLY IN THE PAST HOUR OR TWO. LIGHT
RAIN IS ALL THAT IS LEFT TO THE WEST OF THE LINE CURRENTLY THROUGH
BLOOMSBURG/CARLISLE. THE LINE COULD STILL MAKE SOME GUSTS INTO THE
LOWER 40S BEFORE 10 PM...BUT THE LOW-LEVEL STABILITY IS GETTING
HIGH NOW AS RAIN HAS PROCEEDED THE ARRIVAL OF THE LINE IN THE
LOWER SUSQ. FARTHER TO THE WEST...THE FIRST BLAST OF COLDER AIR IS
ALREADY INTO WARREN COUNTY...AND DEWPOINTS DROPPING QUICKLY
THROUGH THE 40S OVER OHIO AND AS LOW AS 39 JUST ACROSS THE POND.
SCATTERED TO NUMEROUS SHOWERS SHOULD CONTINUE INTO THE NIGHT OVER
THE NWRN HALF OF THE AREA...BUT THERE WILL BE BREAKS IN BETWEEN
THE SHOWERS...ESPECIALLY EARLY. DEFORMATION AXIS PIVOTS ACRS
CENTRAL AND NORTHERN PA VERY LATE TONIGHT/EARLY FRIDAY
MORNING...CONTINUING UNSETTLED CONDITIONS. ONLY EXPECTING A FEW
TENS OF AN INCH FROM THIS ADDITIONAL RAINFALL.
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&&

.SHORT TERM /7 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
A GOOD CHC OF RAIN SHOWERS CONTINUES FRIDAY AS UPPER LOW CUTS OFF
AND PROPAGATES EASTWARD. COOL AIR BEHIND THE SFC COLD FRONT WILL
MAKE FOR A VERY UNPLEASANT DAY. KEPT HIGHEST POPS ACROSS THE
NORTH CENTRAL MTNS IN ANTICIPATION OF OROGRAPHIC ENHANCEMENT ALONG
THE SPINE OF THE APPALACHIANS. THE ARRIVAL OF MUCH DRIER AIR
WRAPPING INTO THE WEST SIDE OF DEVELOPING CUT OFF MAY SHUT OFF
ANY SHOWERS EARLY IN THE DAY ACROSS WARREN CO.

WELL CHANNELED NORTHWEST FLOW AND A TIGHTENING SFC PRESSURE
GRADIENT WILL RESULT IN A BLUSTERY DAY FOR LATE MAY. NORTHWEST
WINDS SHUD GUST BTWN 25-30KTS DURING THE AFTN. TEMPS IN THE
50S...COMBINED WITH THESE GUSTY WINDS...WILL LIKELY RESULT IN
APPARENT TEMPS IN THE 40S DURING THE AFTN ACROSS THE ALLEGHENIES.
BRRR...

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
MAIN CONCERN FRIDAY NIGHT WILL BE THE POTENTIAL OF FROST/FREEZE
HEADLINES ACROSS THE ALLEGHENY PLATEAU. AFOREMENTIONED PRESSURE
GRADIENT APPEARS LIKELY TO KEEP THE WINDS UP FRIDAY NIGHT...SO
WIDESPREAD FROST SEEMS UNLIKELY. HARD TO BELIEVE THERE WILL BE A
WIDESPREAD FREEZE THIS LATE IN THE SEASON WITHOUT A CALM WIND...SO
HAVE LEANED ON THE WARM SIDE OF MOS /CLOSER TO EC MOS/ AND KEPT
TEMPS JUST ABV FREEZING FOR MOST OF THE W MTNS FRI NIGHT.

MDL TREND CONTINUES TO SLOW EASTWARD PROGRESSION OF UPPER
LOW...SO HAVE KEPT MENTION OF SHRA IN THE FCST THRU FRI NIGHT
ACROSS THE EASTERN ZONES...AND TAPERED THEM OFF LATER ACROSS THE
CENTRAL COUNTIES.

EASTERN PA WILL REMAIN ON WESTERN PERIPHERY OF UPPER LOW SAT/SAT
NIGHT. SO...HAVE INCREASED THE CLOUD FCST A BIT OVR THE EASTERN
COUNTIES AND CAN/T COMPLETELY RULE OUT A STRAY SHRA OVR SULLIVAN
OR SCHUYLKILL CO. ELSEWHERE...CONFIDENCE IN A MSUNNY SATURDAY IS
FAIRLY HIGH...AS ALL MDL DATA PULLS LOW PWAT AIR SOUTHWARD ACROSS
CENTRAL/WESTERN PA ON SAT. HOWEVER...DESPITE STRONG MAY
SUNSHINE...MDL 8H TEMPS WELL BLW NORMAL SHOULD CAP READINGS IN THE
L/M 60S ACROSS MUCH OF THE AREA...WITH HIGHS IN THE U50S LIKELY
ACROSS THE HIGH TERRAIN. DEEP MIXING SHOULD DRAW SOME GUSTY WINDS
TO THE SFC AGAIN ON SATURDAY. 800MB WIND FIELDS SUGGEST MUCH OF
THE AREA WILL SEE GUSTS BTWN 25-30KTS BY AFTN.

BULK OF MED RANGE GUIDANCE CONTINUES TO INDICATE A HIGH DEGREE OF
CONFIDENCE IN DRY WX HOLDING THRU MEMORIAL DAY...ALONG WITH A
GRADUAL WARMING TREND...AS UPPER LOW OVR NEW ENG SLOWLY LIFTS AWAY
FROM THE AREA. THE MODELS HAVE SLOWED THE PROGRESSION OF THE
EXITING LOW...SO WITH NW FLOW AND COLDER AIR OVER THE REGION WITH
LIGHT WINDS...THERE REMAINS A CHANCE FOR FROST OVER THE NW MTNS
SUNDAY NIGHT/MONDAY MORNING. THE REST OF THE REGIONS WILL BE IN
THE LOW 40S.

BY THE MIDDLE OF NEXT WEEK...A BUILDING UPPER LVL RIDGE IS
ADVERTISED BY THE MED RANGE GUIDANCE OVR THE MISS VALLEY. ACROSS
THE EAST...SFC HIGH WILL PASS OFF THE COAST...RESULTING IN A
WARMER SW FLOW. SOME MDL DIFFS WITH RESPECT TO HOW FAST THE LOW
LVL MOISTURE RETURNS. HOWEVER...HAVE GRADUALLY INTRODUCED A CHC OF
DIURNAL CONVECTION IN THE TUE/WED TIME FRAME.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
ADJUSTED TAFS FOR BANDS OF SHOWERS AND ISOLATED STORMS.
MUCH OF THE AREA JUST HAS MID LVL CLDS AND DECENT VISIBILITY
AT THE CURRENT TIME.

EXPECT CONDITIONS TO GO DOWN HILL LATER TONIGHT...AS THE UPPER
LEVEL SYSTEM DIGS SE AND STARTS TO CLOSE OFF.

FRIDAY WILL BE A WINDY AND COLD DAY...WITH MVFR AND IFR
CONDITIONS IN MANY SPOTS. FOR NOW...DID BRING CONDITIONS
BACK TO VFR LATER IN THE AFT...GIVEN STRONG SUN ANGLE.

WEEKEND LOOKS OK...BUT BREEZY.

MONDAY SHOULD BE DECENT...AS HIGH BUILDS OVER THE AREA.

COULD BE A FEW SHOWERS AND THUNDERSTORMS LATE TUE...AS
STRONG WARM FRONT MOVES ACROSS THE REGION. STRONG STORMS
COULD FORM...GIVEN VERY STRONG WARM ADVECTION AND DIRECTIONAL
WIND SHEAR. BACK TO SUMMER FOR A FEW DAYS.

HAVE A GOOD HOLIDAY WEEKEND.


.OUTLOOK...
SAT-MON...VFR. NO SIG WX EXPECTED.
TUE...CHC OF SHOWERS AND STORMS LATE.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$
SYNOPSIS...DANGELO/DEVOIR
NEAR TERM...DANGELO
SHORT TERM...DEVOIR
LONG TERM...FITZGERALD/CERU
AVIATION...MARTIN