Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 060313
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1113 PM EDT SUN JUL 5 2015

.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL DRIFT SLOWLY EAST OF THE REGION
TONIGHT. WARM AND HUMID CONDITIONS WILL MOVE BACK INTO
PENNSYLVANIA EARLY IN THE UPCOMING WEEK...BRINGING SEVERAL CHANCES
FOR SCATTERED SHOWERS AND THUNDERSTORMS THROUGH AT LEAST MID WEEK.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
LATE EVENING SATL AND REGIONAL RADAR LOOPS SHOW UPPER LOW LIFTING
NE UP THE OHIO RIVER VALLEY NR KHTS. MUCH OF THE EARLIER CONVECTION
ASSOC WITH THIS FEATURE WAS DIURNALLY-DRIVEN AND IS DISSIPATING AS
IT APPROACHES SOUTHERN PA. WILL CARRY LOW CHC OF SHOWERS THRU
06Z ACROSS ONLY SOMERSET/BEDFORD/FULTON COUNTIES. SITUATION
CHANGES TOWARD DAWN...AS LL JET AND ASSOC PLUME OF ANOMALOUS
PWATS LIFT INTO SOUTHWEST PA. WILL RAMP POPS UPWARD TO ARND 75 PCT
BTWN 06Z-12Z ACROSS THE SOUTHWEST COUNTIES AS THIS FEATURE MOVES
IN.

CLOUDS WILL GRADUALLY THICKEN OVERNIGHT IN RESPONSE TO THE TN
VALLEY UPPER LOW/SHORTWAVE THAT WILL BE OPENING UP AND SLIDING
INTO THE AREA. THE INCREASING CLOUDS...COMBINED WITH RISING
DWPTS...WILL RESULT IN A MILD NIGHT WITH LOWS IN THE 60S...TO NR
70F ACROSS THE LOWER SUSQ VALLEY.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
THE UPPER LOW IS EXPECTED TO WEAKEN/OPEN UP AS IT SWINGS INTO THE
REGION MONDAY. DIMINISHING LG SCALE FORCING OCCURRING DURING AM
CONVECTIVE MINIMUM WILL LIKELY RESULT IN A DWINDLING AREA OF
SHOWERS MOVING INTO SOUTHERN PA LATE MONDAY MORNING.
HOWEVER...REMNANT SOUTHERLY LL JET AND ASSOC PLUME OF ANOMALOUS
PWATS WILL LIE OVR THE AREA. 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.

MDL BLENDED QPF OF A 1/4 TO 1/2 INCH ON AVERAGE SEEMS REASONABLE.
HOWEVER...CONVECTION-ALLOWING MDLS IMPLY LOCALIZED AMTS IN EXCESS
OF 2 INCHES. GIVEN THE WET GROUND AND 1HR FFG VALUES LESS THAN AN
INCH OVR MUCH OF CENTRAL PA...WILL INTRODUCE 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.

MCLDY SKIES AND NUMEROUS PM SHRA/TSRA SHOULD HOLD TEMPERATURES TO
BTWN 75-80F OVR MOST OF CENTRAL PA. HOWEVER...DWPTS PROGGED TO
CREEP INTO THE UNCOMFORTABLE RANGE BTWN 65-70F.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
THE HEART OF A VERY WARM AND MUGGY AIRMASS WILL BE OVER THE STATE
MONDAY NIGHT 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.

LOW TEMPS EARLY TUESDAY WILL BE IN THE L-M 60S ACROSS THE
MTNS...AND UPPER 60S TO AROUND 70F ACROSS THE CENTRAL AND SE
ZONES. HIGHS TUESDAY AFTERNOON WILL RANGE THROUGH THE 80S.

UPPER FLOW BECOMES FAIRLY ZONAL FOR THE MID TO LATE WEEK PERIOD
AND A WEAKENING CFRONTAL BOUNDARY SHOULD SAG JUST TO THE SOUTH OF
THE MASON DIXON LINE...WITH WEAK SFC RIDGING OVER THE STATE
THURSDAY AND FRIDAY. ANY ORGANIZED CONVECTIVE CLUSTERS MOVING
QUICKLY EAST FROM THE OHIO VALLEY IN FAST MID-UPPER LEVEL WESTERLY
FLOW WILL BE VERY DIFFICULT TO TIME AND NOT WORTH ASSIGNING ANY
MORE THAN 30-40 PERCENT POPS AT THIS POINT.

TEMPS AND SFC DEWPOINTS WILL TREND DOWN TO NEAR...OR JUST SLIGHTLY
BELOW NORMAL FOR THE SECOND HALF OF THE WEEK.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
STORMS TO THE SW HAVE WEAKEN. A FEW SHOWERS OVER SW PA STILL.

BEEN WATCHING A BAND OF SHOWERS AND STORMS OVER NORTHERN VA. SO
FAR...ACTIVITY IS WEAKENING. WILL ADJUST 03Z TAFS AS NEEDED.
MAINLY VFR SO FAR...AOO WAS MVFR FOR A BRIEF TIME IN THE CIG
DEPARTMENT.

EARLIER DISCUSSION.

FEW SHOWERS AND STORMS SOUTH OF JST...IN WV AND MD...BUT LEFT
THEM OUT OF THE JST TAF ON THE 21Z TAF UPDATE. WILL CONTINUE
TO MONITOR.

FOR 00Z TAFS...MAIN SITES FOR SHOWERS OVERNIGHT WILL BE JST
AND AOO.

MAIN THING OVERNIGHT WILL BE FOG.

EXPECT SOME SHOWERS ON MONDAY...MAY TAKE SOME TIME TO REACH
IPT...MDT...AND LNS.

YESTERDAY IT LOOKED LIKE LATE MONDAY INTO EARLY TUE WOULD BE
WET. NOW IT LOOKS LIKE THINGS ARE A FEW HOURS FASTER.

A CLOSED UPPER LOW WILL LIFT NORTHEAST FROM THE TN VALLEY TONIGHT
INTO THE CENTRAL APPALACHIANS BEFORE SHEARING OUT OVER THE NRN MID
ATLANTIC MONDAY INTO TUESDAY. AN INCREASINGLY MOIST SOUTH TO
SOUTH-SOUTHEAST LOW LEVEL FLOW IN ADVANCE OF THIS SYSTEM WILL
BRING WIDESPREAD MVFR OR LOWER CONDITIONS INTO THE AIRSPACE
STARTING LATER THIS EVENING AND OVERNIGHT...ALONG WITH SHOWERS AND
SCATTERED THUNDERSTORMS MONDAY INTO MONDAY NIGHT.

A COLD FRONT SHOULD BRING ANOTHER ROUND OF SHOWERS AND STORMS TO
THE AREA ON TUESDAY INTO WEDNESDAY. THE FRONT IS FCST TO STALL OUT
NEAR THE PA/MD BORDER WHICH WILL ALLOW FOR ADDITIONAL
OPPORTUNITIES FOR PCPN THROUGH THE END OF THE WEEK.

OUTLOOK...

TUE...CHC OF SHOWERS AND THUNDERSTORMS.
WED...MOST AREAS DRY...BUT STILL SOME RISK OF SHOWERS AND
STORMS...MAINLY NEAR THE MD BORDER.
THU-FRI...VFR/MVFR WITH CHC OF SHOWERS/PM TSTMS.

&&

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

&&

$$
SYNOPSIS...LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD/LA CORTE
LONG TERM...LAMBERT/GARTNER
AVIATION...LA CORTE/MARTIN


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