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000
FXUS61 KCTP 150751
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
351 AM EDT WED MAY 15 2013

.SYNOPSIS...
A WARM FRONT OVER THE UPPER OHIO VALLEY WILL PUSH EASTWARD ACROSS
CENTRAL PENNSYLVANIA THIS MORNING...FOLLOWED BY A COLD FRONT THAT
WILL DROP SOUTHWARD FROM THE LOWER GREAT LAKES LATE THIS AFTERNOON
INTO EARLY TONIGHT. THE COLD FRONT WILL BECOME QUASI-STATIONARY
OVER THE CENTRAL APPALACHIANS AND SOUTHERN MID-ATLANTIC STATES
INTO THE WEEKEND BEFORE RETURNING BACK TO THE NORTH AS A WARM
FRONT EARLY NEXT WEEK. ANOTHER COLD FRONT SHOULD CROSS THE REGION
AROUND THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
WEAK SHORTWAVE CROSSING LWR MI COMBINED WITH STG 850-700MB
THETA-E ADV/WSWLY FLOW IMPINGING ON NW-SE ORIENTED WARM FRONTAL
ZONE CONTINUES TO PRODUCE LGT SHOWER ACTIVITY INVOF LK ERIE. HI-
RES MDLS HAVE BEEN HANDLING THE WAA PCPN REASONABLY WELL THUS
FAR...AND SHOW THE LGT SHOWERS REACHING THE NW-WRN MTNS BTWN
09-12Z...EXPANDING INTO THE N-CNTRL ZONES BTWN 12-15Z. THE WARM
FRONT SHOULD LIE NEAR KPEO-KIPT-KMDT LINE AROUND 18Z BEFORE
SHIFTING EWD INTO NJ BY 21Z.

EMPHASIS IN THE NEAR TERM FCST CONTINUES TO BE ON SEVERE POTENTIAL
LATER TODAY. AN UPPER-LEVEL TROUGH WILL MOVE EWD ACRS SERN CANADA
WITH TRIPLE-POINT SFC LOW TRACKING EWD ACRS SRN ONT THEN NEWD THRU
THE ST. LAWRENCE VLY. THE TRAILING COLD FRONT WILL BE THE TRIGGER
FOR TSTMS THIS AFTN AS IT PUSHES SEWD ACRS THE LWR LKS INTO WRN
NY/PA. SOME MODELS /I.E. THE NAM/ STILL APPEAR TO BE TOO BULLISH
WITH LLVL MSTR SHOWING DEWPOINTS IN THE MID 60S OVER CNTRL PA
AHEAD OF THE COLD FRONT. UPSTREAM OBS INDICATE SFC DEWPOINTS ARE
MORE LKLY BE IN THE UPPER 50S F RESULTING IN SB CAPE VALUES BTWN
500 TO 1000 J/KG - ABOUT 1/2 OF THE CAPE THE NAM IS GENERATING.
STILL...THIS AMT OF INSTABILITY SHOULD BE SUFFICIENT FOR STORM
INITIATION. THE DEEP-LAYER SHEAR IS MORE ROBUST WITH MEAN 0-6KM
VALUES AROUND 40KTS AND UNIDIRECTIONAL WIND PROFILES. THIS
CAPE/SHEAR ENVIRONMENT SHOULD BE MORE THAN ADEQUATE TO SUPPORT
SOME ORGANIZED STORM STRUCTURES WITH THE MAIN TSTM HAZARD BEING
DAMAGING WINDS. MAY COORDINATE WITH NEIGHBORING OFFICES AND SPC
LATER THIS MORNING TO GET THEIR THOUGHTS ON POSSIBLE CATEGORICAL
UPGRADE TO SLGT RISK.

THE FRONT WILL PUSH SWD ACRS S-CNTRL PA DURING LATE EVE AND SHOULD
REACH THE MASON-DIXON LINE BY 03Z. THE THREAT OF SHOWERS AND TSTMS
WILL DECREASE FROM NORTH-SOUTH FROM LATE AFTN INTO EARLY TONIGHT
WITH POPS TAPERING DOWN TO SCHC AFT 06Z IN THE FAR SRN TIER PER
CONS MDL BLEND.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
W-E ORIENTED Q-STNRY FRONTAL BOUNDARY SHOULD LINGER JUST SOUTH OF
THE PA/MD BORDER EARLY THURS AM BEFORE SLOWLY SINKING SWD INTO
WV/VA. KEPT SOME SCHC TO LOW CHC POPS ALONG/SOUTH OF THE PA
TURNPIKE FOR DAY 2 WITH ANY AFTN CONVECTION REMAINING ISOLD TO SCT
AT BEST. OR TO PUT IT ANOTHER WAY...MOST OF THE CWA SHOULD BE DRY.

A WEAK SECONDARY/BACKDOOR COLD FRONT SHOULD PUSH SWD ACRS CNTRL PA
LATER THURS...BEFORE SFC RIDGING TAKES HOLD OVER THE AREA TOMORROW
NGT INTO DAY 3. DAYTIME MAXES SHOULD RANGE BTWN 70-80F WITH SOME
LOCATIONS OVER THE ERN VALLEYS CLIMBING INTO THE LOW 80S. LOWS
WILL VARY FROM AROUND 40F IN THE NORTH TO THE LOW 50S ALONG THE
SRN TIER ZONES.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
OTHER THAN CHANCE FOR SHOWER/TSTM ACROSS SOUTHERN TIER AS SERIES
OF WEAK SHORTWAVES SLIDE OVER OLD FRONTAL BOUNDARY...FCST SHOULD
BE DRY THU THROUGH SAT. /GFS IS SHOWING PRECIP ACROSS CENTRAL PA
ON SAT...BUT APPEARS TO BE A CONVECTIVE FEEDBACK ISSUE AND WENT
WITH THE PRECIP-FREE ECMWF./ TEMPS HAVE BEEN TEMPERED BACK JUST A
BIT BASED ON NEW GUIDANCE...WITH THE COOLEST TEMPS IN THE NE. BUT
NEAR SEASONAL LEVELS FOR MOST PLACES.

WAVY FRONTAL BOUNDARY WILL RETURN NWD AS WARM FRONT DURING THE
LATE WEEKEND...AND ESP EARLY NEXT WEEK AS LOW PRES OVER N PLAINS
DEVELOPS FURTHER AS IT MOVES INTO THE WRN GRT LKS. SW FLOW WILL
BRING INCREASING WARMTH AND MOISTURE IN THE WARM SECTOR...
RESULTING IN BETTER CHANCES FOR SHOWERS/TSTMS EARLY NEXT WEEK.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
LIGHT SHOWERS AND SPRINKLES ASSOCIATED A WEAK RIPPLE IN THE NW
FLOW ALOFT CONTINUE TO LINGER ACROSS SMALL PORTIONS OF THE LOWER
SUSQ AS OF 2 AM. LOW LEVEL STRATOCU CONTINUES TO LAY ACROSS THE
REGION WITH LIGHT WINDS. THIS WILL TEMPER ANY FOG/MIST FROM
DEVELOPING...THOUGH SOME PATCHY FOG/MIST SHOULD DEVELOP IN THE
LOW LYING REGIONS OVERNIGHT...WHICH CURRENTLY HAS CAUSED UNV TO GO
MVFR.

SHOWERS ASSOCIATED WITH MOISTURE RIPPLING UNDERNEATH A SHORTWAVE
FROM THE NORTHWEST IS CURRENTLY MAKING ITS WAY ACROSS LAKE ERIE.
EXPECT THOSE SHOWERS AND ACCOMPANYING MOISTURE TO REACH THE AREA THIS
MORNING...BETWEEN 11-15Z. THESE SHOWERS WILL CONTINUE THROUGH MID
MORNING. COUPLED WITH THIS WILL BE GRADUALLY LOWERING CEILINGS AS
WARM- MOIST ADVECTION CONTINUES WITH THE APPROACH OF THE SLOW
MOVING WARM FRONT CURRENTLY ENTERING SWRN PA. EXPECT MVFR TO
DEVELOP OVER MUCH OF WESTERN AND CENTRAL PA BETWEEN ABOUT 10-15Z.
AT THIS TIME SUSQ VALLEY TERMINALS LOOK LIKE THEY SHOULD REMAIN
MAINLY ABOVE 3000` CEILINGS.

WEDNESDAY WILL BE TUMULTUOUS AS THE WARM FRONT PASSES
THROUGH...USHERING IN WARMER...MOISTER AND MORE UNSTABLE
CONDITIONS. A COLD FRONT WILL THEN APPROACH LATE IN THE DAY WHICH
WILL LIKELY TRIGGER SHOWERS AND SCATTERED THUNDERSTORMS. SOME OF
THE STORMS COULD BE ACCOMPANIED BY STRONG WINDS AND HAIL.

.OUTLOOK...

THU-FRI...NO SIG WX EXPECTED.

SAT-SUN...MAINLY VFR. PM TSRA PSBL...MAINLY S.

&&

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

&&

$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...RXR
AVIATION...LA CORTE/CERU