270
FXUS61 KCTP 240346
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1146 PM EDT THU MAY 23 2013

.SYNOPSIS...
A COLD FRONT WILL CROSS THE COMMONWEALTH TONIGHT AND EARLY
FRIDAY. AN UPPER LOW WILL TRAVERSE THE REGION ON FRIDAY PROVIDING
COOL...SHOWERY...AND ALMOST BLUSTERY 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 FRIDAY MORNING/...
SCATTERED TO NUMEROUS LIGHT SHOWERS SHOULD TAPER OFF IN THE NEXT
2-3 HRS IN THE EAST. CURRENT BATCH OF SHOWERS IN THE LAURELS IS
FCST TO DISSIPATE AS IT MOVES EAST OVER THE NEXT FEW HRS...BUT
SHOWERS WILL RETURN TO THE NW CO.S AS THE COLD AIR CONTINUES TO
POUR IN FROM THE NW. WILL KEEP POPS AT 30-50 PCT THERE DUE TO THE
SCT NATURE - BUT ALMOST EVERYONE WILL GET WET OVERNIGHT IN THE
NWRN HALF OF THE CWA. ONLY EXPECTING A FEW HUNDRETHS/TENTH OF AN
INCH OR SO FROM THIS ADDITIONAL RAINFALL.

&&

.SHORT TERM /8 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
RAIN SHOWERS LIKELY FRIDAY MORNING OVER MOST OF THE AREA AND WILL
CONTINUE FOR MOST OF THE DAY IN THE EAST 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 /04Z FRIDAY THROUGH TUESDAY/...
MOST OF THE THUNDER NOW EAST OF THE AREA NOW. PERHAPS
A BRIEF RUMBLE AT MDT OR LNS FOR A FEW MORE HOURS.

CIGS STARTING TO COME DOWN AS EXPECTED.

EXPECT CONDITIONS TO CONTINUE TO GO DOWN HILL OVERNIGHT...
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