Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 060948
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
548 AM EDT MON JUL 6 2015

.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL MOVE BACK INTO PENNSYLVANIA EARLY
THIS WEEK. A WEAKENING...BUT MOISTURE LADEN WAVE OF LOW PRESSURE
AT THE SURFACE AND ALOFT WILL DRIFT NORTH INTO THE REGION TODAY
BRINGING WITH IT NUMEROUS...MAINLY AFTERNOON SHOWERS...ALONG WITH
ISOLATED THUNDERSTORMS THAT COULD DUMP LOCALLY HEAVY RAIN. AFTER A
MAINLY RAIN-FREE TUESDAY...A COLD FRONT WILL PUSH SOUTHEAST ACROSS
THE STATE TUESDAY NIGHT. THE COLD FRONT WILL STALL OUT NEAR...OR
JUST SOUTH OF THE MASON DIXON LINE LATER THIS WEAK. THIS BOUNDARY
WILL ACT AS A PATHWAY FOR A FEW WAVES OF LOW PRESSURE TO RIPPLE
EAST ALONG AND BRING A FEW MORE ROUNDS OF SHOWERS AND
THUNDERSTORMS LATE WEDNESDAY...AND AGAIN THURSDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EARLY MORNING RADAR/SATELLITE BLEND SHOWS SHOWERS SPREADING INTO
THE SOUTHERN TIER COUNTIES OF PENN...ASSOCIATED WITH A SLOW
MOVING UPPER TROUGH OVER WEST VA.

ANOMALOUSLY HIGH PWAT AIR OF 45-50MM WILL SPREAD NORTH OVER THE
ENTIRE CWA BY LATE THIS AFTERNOON. MOISTURE FLUX...HELPED ALONG BY
A PLUS 2 SIGMA /20-25 KT/ SOUTHERLY FLOW AT 850 MB...WILL BE
FOCUSED RIGHT ACROSS THE REGION LATE THIS MORNING AND THIS
AFTERNOON.

SREF/S PROB OF CAPE EXCEEDING 1000 J/KG IS LOWEST ACROSS THE NCENT
MTNS THIS AFTERNOON AND THIS EVENING...AND 70-80 PERCENT INVOF
KMDT...KTHV AND KLNS. MODEST HEATING OF THIS AIR MASS SHOULD
PRODUCE NUMEROUS PM SHRA/TSRA. CONTINUE TO LEAN TOWARD SREF AND
GEFS POPS...WHICH SUPPORT CATEGORICAL POPS OVR MUCH OF CENTRAL PA

INCREASING DIFLUENCE AHEAD OF THE AFOREMENTIONED UPPER TROUGH
WILL COMBINE WITH THE MDTLY HIGH MIXED LAYER INSTABILITY AND
SHEAR TO PRODUCE FREQUENT-SHOWERS /AND THE OUTSIDE CHC OF A
THUNDERSTORM/.

MDL BLENDED QPF OF A 1/4 TO 1/2 INCH SEEMS REASONABLE FOR BASIN
AVERAGE AMOUNTS. HOWEVER ...CONVECTION-ALLOWING MDLS IMPLY
LOCALIZED AMTS IN EXCESS OF 2 INCHES IN PLACES THAT SEE A FEW
TRAINING TSRA.

GIVEN THE WET GROUND AND 1HR FFG VALUES LESS THAN AN INCH OVR
MUCH OF CENTRAL PA...WILL MAINTAIN THE MENTION OF LOCAL FLOODING
IN THE HWO. BEST CHC OF LOCALLY EXCESSIVE RAINFALL SHOULD BE
ACROSS THE WESTERN AND SOUTHERN COUNTIES...WHERE MDL INSTABILITY
THE GREATEST. WEAK FLOW ALOFT AND PRACTICALLY NON- EXISTENT DCAPE
DUE TO LACK OF MID LVL DRY AIR SIGNALS A LOW CHC OF SVR WEATHER.

GREATER PROBABILITY FOR HIGH CAPE /EXCEEDING 2000 J/KG/ EXISTS
ACROSS THE LOWER SUSQ VALLEYS AND ADJACENT COMMUNITIES THIS
AFTERNOON AND EARLY THIS EVENING. SPC HAS ACCOUNTED FOR THIS AREA
OF LOCALLY HIGH PRECIP POTENTIAL...INSTABILITY...AND WEAK TO MDT
SOUTHERLY LLVL SHEAR BY PLACING SCENT PENN AND ADJACENT PORTIONS
OF THE LOWER SUSQ VALLEY UNDER A MARGINAL RISK FOR SVR TSRA LATE
THIS AFTERNOON INTO THIS EVENING.

TEMPS WILL START OUT BE MILD EARLY TODAY...WITH DAYBREAK LOWS
RANGING FROM THE U50-L60S ACROSS THE NRN HALF OF PENN...TO NR 70F
OVER THE LOWER SUSQ VALLEY.

HIGHS THIS AFTERNOON /IN THE INCREASING MUGGINESS/ WILL BE IN THE
MID 70S ACROSS THE LAUREL HIGHLANDS AND U70S TO NEAR 80F
ELSEWHERE. DEWPOINTS ARE PROGGED TO CREEP INTO THE UNCOMFORTABLE
RANGE BTWN 65-70F.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
THE HEART OF A VERY WARM AND MUGGY AIRMASS WILL BE OVER THE STATE
TONIGHT AND TUESDAY WITH MAINLY RAIN-FREE CONDITIONS BETWEEN
04-20Z TUESDAY. LATER TUESDAY AFTERNOON ISOLATED TO SCATTERED
CONVECTION WILL FORM INVOF A LEE TROUGH...AND IN ADVANCE OF A SFC
COLD FRONT APPROACHING FROM THE OHIO VALLEY.

MUCH OF THE ENERGY PUSHING THIS FRONT EASTWARD APPEARS THAT IT/LL
BE SHEARING OFF TO THE ENE ACROSS SRN ONTARIO AND QUEBEC. STILL A
CLOSE CALL ENOUGH CALL FOR ADEQUATE DEEP-LAYER SHEAR TO BRING
SCATTERED SHOWERS...AND ISOLATED STRONG TO POSSIBLY SVR TSRA
/MAINLY ACROSS THE WEST/ LATE IN THE DAY TUESDAY AND TUESDAY
NIGHT.

WARMING TEMPS IN THE MID LEVELS /FROM 7C...UP TO 9C TUESDAY
AFTERNOON AND EVENING/ WILL HELP TO GREATLY LIMIT/CAP OFF SHOWERS
AND TSRA ACROSS MUCH OF CENTRAL PENN AND THE SUSQ VALLEY.

HIGH TUESDAY WILL LIKELY BE THE WARMEST THIS WEEK...AND ABOUT 3-4
DEG F ABOVE NORMAL.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
THE 07/00Z MODEL AND ENSEMBLE GUIDANCE IS PROVIDING A FAIRLY
CONSISTENT SIGNAL THAT THE AREA WILL REMAIN IN A LOW AMPLITUDE
QUASI-ZONAL MID/UPPER FLOW PATTERN WITHIN THE NORTHERN STREAM
WESTERLIES. AS MIGHT BE EXPECTED IN THIS PATTERN...THERE IS LOW
PREDICTABILITY/CONFIDENCE GIVEN DEGREE OF SPREAD AND MEANINGFUL
DIFFERENCES ASSOCIATED WITH SHORTWAVE DETAILS. THIS LARGELY
UNSETTLED AND RECENTLY PERSISTENT WEATHER PATTERN FOR THE LOCAL
AREA WILL BE MODULATED TO SOME EXTENT BY RETROGRESSION OF
UNSEASONABLY STRONG UPPER TROUGH/RIDGE COUPLET OFF THE WEST COAST
AND OVER THE SOUTHEAST AND SCENTRL U.S. THERE IS BROAD SUPPORT FOR
ANOTHER MEAN TROUGH TO DEVELOP OVER THE NORTHEAST/MID ATLANTIC
STATES BY NEXT WEEK/JULY 13TH AS ENERGY EJECTING FROM CA UPPER LOW
EVOLVES DOWNSTREAM IN THE WESTERLIES AND TEAMS WITH VORTEX OVER
HUDSON BAY.

IN TERMS OF SENSIBLE WEATHER...A WELL-DEFINED COLD FRONT ENTERS
CENTRAL PA EARLY WEDNESDAY ACCOMPANIED BY SHOWERS/TSTMS...THEN
BECOMES WAVY AS IT STALLS OUT FROM NEAR THE OH RIVER/MASON DIXON
LINE. EXPECT ONE OR MORE EPISODES OF PCPN THRU LATE WEEK MOST LKLY
DUE TO MCS REMNANTS OR CONVECTIVELY INDUCED LOWS TRACKING EWD FROM
THE MID MS/OH VLY...BUT TOO DIFFICULT TO PIN POINT TIMING/LOCATION
AT THIS POINT. FWIW THE MODEL BIAS IS USUALLY TOO FAR NORTH WITH
MCS ACTIVITY. PCPN RISK SHOULD EVENTUALLY BE ENHANCED TOWARD THE
END OF THE PERIOD INTO EARLY NEXT WEEK AS CA LOW ENERGY AND
ASSOCIATED SFC SYSTEM REACHES THE GREAT LAKES.

WHAT WE CAN SAY WITH RELATIVE CERTAINTY IS THAT WE DO NOT EXPECT
ANY HEAT WAVES OR EXTENDED PERIODS OF DRY WEATHER OVER THE NEXT 7+
DAYS.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
07/09Z UPDATE...ADJUSTED TAFS FOR IFR CIGS AT JST/LNS/IPT.

07/06Z...EXPECT SHOWER ACTIVITY TO INCREASE IN COVERAGE AND
SPREAD FROM SOUTH TO NORTH THROUGH THE AFTERNOON...AS AN UPPER
LEVEL LOW CURRENTLY OVER WV/KY AND SFC WARM FRONT LIFTS NEWD ALONG
THE CENTRAL APPALACHIANS. LOW VFR TO MVFR CIGS ARE FCST ACROSS
MUCH OF THE AIRSPACE THRU THE PERIOD. SHOWERS WILL TEND TO BE
SLOW-MOVG AND COULD PRODUCE HEAVY DOWNPOURS AND LCL IFR VISBYS.
THE UPPER LOW WILL WEAKEN OVER CENTRAL PA INTO TNGT BUT STILL
MAINTAIN SCT SHOWER RISK...THEREFORE SIMPLY WENT WITH VCSH AFT
00Z. CIGS/VSBYS SHOULD TREND GRADUALLY LOWER OVERNIGHT GIVEN
DIURNAL COOLING...HIGH LOW LEVEL MSTR/NARROW T-TD SPREADS AND LGT
WINDS...WITH AT LEAST MARGINAL RESTRICTIONS LKLY AT SEVERAL SITES
INTO EARLY TUESDAY. LOWER CONDITIONS TUESDAY MORNING SHOULD
IMPROVE BY AFTN. A COLD FRONT WILL APPROACH THE AIRSPACE FROM THE
LWR LKS/OH VLY BY LATE IN THE DAY AND SHIFT SLOWLY SEWD INTO THE
AIRSPACE TUE NGT/WED BEFORE STALLING OUT NEAR PA/MD BORDER THURS
INTO FRIDAY.

OUTLOOK...

TUE-FRI...VFR/MVFR WITH PERIODS OF SHRA/AFTN TSTMS.

&&

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

&&

$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...LAMBERT
LONG TERM...STEINBUGL
AVIATION...STEINBUGL


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