000
FXUS61 KCTP 240938
AFDCTP

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

.SYNOPSIS...
A COLD FRONT EXTENDING FROM THE POCONOS TO THE LOWER SUSQUEHANNA 
VALLEY EARLY TODAY WILL PUSH OFF THE MID ATLANTIC COAST THIS 
AFTERNOON. 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. EARLY MORNING LOWS BOTH SATURDAY AND SUNDAY WILL DIP 
NEAR...OR SLIGHTLY BELOW FREEZING OVER THE NORTHERN AND WESTERN 
MOUNTAINS OF THE STATE.  

&&

.NEAR TERM /THROUGH TONIGHT/...
STRONG...SFC COLD FRONT EXTENDED FROM KAVP...SW TO KSEG AND JUST 
WEST OF KMDT AT 09Z. TEMPS WERE IN THE U50S TO L60S JUST AHEAD OF 
THE FRONT...ACROSS THE LOWER SUSQ VALLEY...WHILE READINGS RANGED 
THROUGH THE 40S ACROSS THE NRN AND WRN MTNS...AND AROUND 50F ACROSS 
THE CENTRAL MTNS.

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.

08Z GFS LAMP GUIDANCE AND 00Z NAM INDICATES THE POTENTIAL FOR SOME 
FLEETING WET SNOW TO BE MIXED IN AT TIMES WITH THE SHOWERS ACROSS 
MAINLY ELEVATION AOA 1800 FT MSL ACROSS THE LAURELS AND NW MTNS 
DURING THE MID TO LATE MORNING HOURS.

ONLY EXPECTING A FEW HUNDREDTHS /TO PERHAPS ONE TENTH OF AN INCH OF 
ADDITIONAL RAINFALL IN A FEW LOCATIONS/ THROUGH THE MID 
MORNING...THEN MORE NUMEROUS AND BRIEFLY HEAVIER SHOWERS ARE LIKELY 
DO DEVELOP IN THE COOL/UNSTABLE AIRMASS FOR THE AFTERNOON HOURS 
BRINGING AN ADDITIONAL TENTH OF AND INCH OR SO TO SOME LOCATIONS. 

TEMPS WILL DIP INTO THE MID AND 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...AND RISE JUST A 
FEW DEGREES THIS AFTERNOON. READINGS 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.

WELL CHANNELED NORTHWEST FLOW AND A TIGHTENING SFC PRESSURE GRADIENT 
WILL RESULT IN A BLUSTERY DAY FOR LATE MAY. NORTHWEST WINDS SHOULD 
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.

THE SHOWERS WILL GRADUALLY DIMINISH LATE TODAY/EARLY THIS EVENING 
ACROSS CENTRAL AND WESTERN SECTIONS OF THE CWA...WITH SOME ISOLATED 
TO SCTD SHOWERS LIKELY LINGERING INTO EARLY SATURDAY ACROSS THE SUSQ 
VALLEY AND POINTS EAST AS THE UPPER LOW CUTS OFF AND PROPAGATES ONLY 
SLOWLY EASTWARD.

THE AIRMASS IS COLD ENOUGH EARLY SATURDAY TO SUPPORT MIN TEMPS 
SETTLING AROUND...OR PERHAPS A FEW DEG F BELOW THE FREEZING MARK 
ACROSS THE NW MTNS AND LAURELS. COORDINATED WITH SURROUNDING OFFICES 
TO POST A FREEZE WARNING FOR THE 06-13Z PERIOD SATURDAY.. 


&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...

MORNING SUNSHINE SATURDAY WILL BECOME MIXED WITH FLAT TO MDT 
AFTERNOON CU ACROSS MOST AREAS. ONE OR TWO POCKETS OF COLDER AIR 
ALOFT AND STEEPER MID-LEVEL LAPSE RATES WILL BE SLIDING SE ACROSS 
THE EASTERN HALF OF PENN DURING THE DAY. THIS EXPECTED BOOST OF 
INSTABILITY ALOFT SHOULD BRING PERIODS OF AT LEAST BKN CLOUDS AND 
ISOLATED SHOWERS TO AREAS NEAR AND TO THE EAST OF THE SUSQ MAINSTEM 
AND NORTH BRANCH.

TEMPS FOR SATURDAY AFTERNOON SHOULD MODERATE BY SOME 8-12F COMPARED 
TO FRIDAY/S HIGHS.  
 
SIMILARLY COLD CONDITIONS /TO THOSE OF EARLY SATURDAY/ ARE VERY 
POSSIBLE FOR EARLY SUNDAY MORNING...AND THE CHANCE FOR FROST WILL 
ALSO BE GREATER ACROSS THE NORTHERN AND WESTERN MTNS GIVEN 
DIMINISHING NW WINDS AND CLEAR TO PTLY CLOUD SKIES. 

PATCHY FROST IS EXPECTED ACROSS THE CENTRAL RIDGE AND VALLEY REGION 
WHERE MIN TEMPS IN THE MID AND UPPER 30S WILL BE COMMON. LOWS ACROSS 
MUCH OF THE LOWER SUSQ VALLEY WILL BE WITHIN A DEG OR TWO OF 40F.   

HEIGHTS GRADUALLY RISE SUNDAY AS THE DEEP UPPER LOW PULLS SLOWLY 
AWAY ACROSS THE NEW ENGLAND STATES. HIGH PRESSURE CENTERED OVER THE 
UPPER GLAKES WILL RIDGE SE ACROSS THE COMMONWEALTH BRINGING ABUNDANT 
SUNSHINE AND A NORTHWEST BREEZE OF 7-12KTS DURING THE LATE MORNING 
AND AFTERNOON.

HIGH PRESSURE WILL BE OVERHEAD SUNDAY NIGHT BRINGING CLEAR 
SKIES...NEAR CALM AIR AND A THIRD...AND FINALLY NIGHT OF CHILLY /AND 
POSSIBLE FROSTY/ CONDITIONS. MIN TEMPS EARLY MONDAY WILL VARY FROM 
THE LOWER 30S ACROSS THE NW MTNS...TO THE LOWER AND MID 40S 
THROUGHOUT THE MIDDLE AND LOWER SUSQ VALLEY.    

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
THE 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 /09Z FRIDAY THROUGH TUESDAY/...
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.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
FREEZE WARNING FROM 2 AM TO 9 AM EDT SATURDAY FOR PAZ004>006-
010-011-017-024-033.

&&

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