-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 240647
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
247 AM EDT FRI MAY 24 2013

.SYNOPSIS...
A COLD FRONT WILL PUSH ACROSS CENTRAL PENNSYLVANIA AND THE
SUSQUEHANNA VALLEY EARLY TODAY. AN UPPER LOW WILL TRAVERSE THE
REGION DURING THE DAY TODAY PROVIDING UNSEASONABLY COOL...SHOWERY
AND QUITE BREEZY CONDITIONS. CANADIAN HIGH PRESSURE WILL BUILD OVER
PENNSYLVANIA AND BRING DRIER WEATHER ON SATURDAY WHICH SHOULD LAST
THROUGH REST OF THE MEMORIAL DAY WEEKEND. TEMPERATURES WILL TREND
COLDER OVER THE NEXT FEW DAYS...BEFORE MODERATING THROUGH THE EARLY
TO MIDDLE PART OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
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STRONG...SFC COLD FRONT EXTENDED FROM THE FINGER LAKES REGION OF NEW
YORK...SSW TO THE LAUREL HIGHLANDS. TEMPS WERE IN THE U50S TO L60S
AHEAD OF THE FRONT...ACROSS ROUGHLY THE SE HALF OF PENN AT 06Z...AND
SLIDING THROUGH THE 50S ACROSS MUCH OF THE ALLEGHENY PLATEAU. TEMPS
HAVE DIPPED INTO THE LOWER TO MID 40S ACROSS EXTREME NWRN PENN...AND
THE MEAN 925-850 0C WET BULB LINE IS ALONG THE NORTH SHORE OF LAKE
ERIE.

SCATTERED RAIN SHOWERS WILL BE DRIFTING EAST OR NORTHEAST ACROSS THE
ENTIRE CWA THROUGH THE MID MORNING HOURS AS THE CFRONT /AND STRONG
DIFF PVA IN ITS WAKE/ MOVES OVER THE REGION.

900-850MB WET BULB TEMPS WILL FALL TO -1 TO -2C ACROSS THE NRN AND
WRN MTNS OF PENN BEGINNING IN THE 09-12Z PERIOD...AND REMAIN THERE
THROUGH 16Z BEFORE MODERATING A TAD THIS AFTERNOON.

05Z GFS LAMP GUIDANCE AND 00Z NAM INDICATES THE POTENTIAL FOR SOME
WET SNOW TO BE MIXED IN WITH THE SHOWERS ACROSS MAINLY ELEVATION AOA
1800 FT MSL ACROSS THE LAURELS AND NW MTNS DURING THE MID TO LATE
MORNING.

ONLY EXPECTING A FEW HUNDREDTHS /TO PERHAPS ONE TENTH OF AN INCH OF
ADDITIONAL RAINFALL IN A FEW LOCATIONS/ THROUGH THE MID MORNING.

TEMPS WILL DIP INTO THE UPPER 30S FOR SEVERAL HOURS DURING THE LATE
MORNING AND MIDDAY HOURS ACROSS THE NRN AND WRN MTNS BEFORE
REBOUNDING A BIT THIS AFTERNOON. THE MERCURY WILL SLOWLY FALL TO THE
UPPER 40S AND LOWER 50S ACROSS THE CENTRAL MTNS. TEMPS CURRENTLY IN
THE LOWER 60S ACROSS THE SUSQ VALLEY...WILL SLOWLY FALL INTO EARLY
THIS AFTERNOON...REACHING THE LOWER TO MID 50S...THEN STAY STEADY
FOR THE REST OF THE DAY.
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&&

.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM SATURDAY/...
SHOWERS WILL GRADUALLY DIMINISH BY THIS AFTERNOON IN THE WEST...BUT
WILL BE LIKELY FOR MOST OF THE DAY ACROSS THE ERN HALF OF THE CWA
AS THE 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 40S AND
50S...COMBINED WITH THESE GUSTY WINDS...WILL LIKELY RESULT IN
APPARENT TEMPS IN THE 30S DURING THE AFTN ACROSS THE
ALLEGHENIES...AND 40S ELSEWHERE. BRRR...

&&

.LONG TERM /SATURDAY 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 /06Z FRIDAY THROUGH TUESDAY/...
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AN UNSEASONABLY STRONG/DEEP UPPER-LEVEL TROUGH WILL ROTATE EWD
FROM THE LWR GRT LKS/OH VLY THROUGH THE MID-ATLC AND NORTHEAST
STATES OVER THE NEXT 48-72 HOURS. A COLD AND BLUSTERY NNW FLOW
WILL ACCOMPANY WIDESPREAD STRATUS/STRATOCU WITH MVFR AND IFR CONDS
CONTINUING THROUGH THE FIRST PART OF TODAY. PEAK WIND GUSTS THIS
AFTN WILL TOP-OUT IN THE 25-35KT RANGE...WITH THE HIGHEST GUSTS
FCST AT MDT/LNS. GIVEN THE ANOMALOUS PATTERN...GUIDANCE MAY BE TOO
QUICK WITH IMPROVING CIGS ALTHOUGH SHALLOW MIXING AND DRY AIR
ADVECTION SHOULD LIFT BASES OUT OF IFR RANGE. VFR/MVFR CIGS LATE
TODAY WILL EVENTUALLY GIVE WAY TO A PROLONGED PERIOD OF VFR FLYING
OVER THE HOLIDAY WEEKEND...AS CANADIAN HIGH PRESSURE DRIFTS SEWD
FROM THE GREAT LAKES.

.OUTLOOK...
SAT-SUN...VFR. GUSTY NW WINDS.
MON...VFR. NO SIG WX EXPECTED.
TUE...SCT PM TSTM IMPACTS POSSIBLE.
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&&

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

&&

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