Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 012220
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
620 PM EDT MON SEP 1 2014

.SYNOPSIS...
WARM AND HUMID CONDITIONS WILL CONTINUE INTO TUESDAY UNTIL A COLD
FRONTAL PASSAGE BRINGS DRIER AND SLIGHTLY COOLER AIR TO CENTRAL
PENNSYLVANIA THROUGH MID WEEK. HUMIDITY WILL RETURN TOWARD THE
END OF THE WEEK AHEAD OF THE NEXT FRONTAL SYSTEM THAT WILL BRING
THE CHANCE OF RAIN FOR THE UPCOMING WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
FAIRLY TRANQUIL LATE SUMMER EVENING TO CLOSE LABOR DAY HOLIDAY
WEEKEND OVER CENTRAL PA...AFTER SOME EARLIER HEAVY DOWNPOURS
TRACKED ACROSS SOME PORTIONS OF THE CENTRAL AND SOUTH CENTRAL
MOUNTAINS. THESE WERE ASSOCIATED WITH A SHORTWAVE TROF WHICH
TRACKED INTO THE CATSKILLS THIS EVENING. FARTHER SOUTH...ANOTHER
SHORTWAVE TROF TRACKING FROM THE WV PANHANLDE TO SOUTHERN MD
TOUCHED OFF ISOLATED COVERAGE OF SHOWERS AND A FEW THUNDERSTORMS
FROM SOUTHEAST PA THROUGH CENTRAL NJ. A THIRD UPPER TROF IS
APPROACHING SOUTHWEST PA FROM NRN KY AND EXTREME SOUTHERN
OH...INITIATING ISOLATED TO SCATTERED SHOWER ACTIVITY ACROSS
SOUTHWEST PA AND EXTENDING INTO THE WEST CENTRAL MOUNTAINS AT THIS
HOUR. MAIN CONVECTIVE ACTIVITY IS FAR WEST OF CENTRAL
PA...OCCURRING WITH THE SFC COLD FRONT EXTENDING FROM SOUTHEAST
MICHIGAN INTO NORTHWEST OHIO AND EASTERN INDIANA THIS EVENING.

UPSTREAM STORMS SHOULD WEAKEN POST SUNSET...WITH FOCUS FOR
CONVECTION SHIFTING WESTWARD TOWARDS THE APPROACHING COLD FRONT...
EXPECTED TO CROSS CENTRAL PA TUESDAY AFTERNOON AND EVENING.

AREAS OF FOG AND LOW CLOUDS WILL FORM ONCE AGAIN LATE TONIGHT WITH
WINDS REMAINING LIGHT AND LLVL MOISTURE ABUNDANT. IT WILL BE MUGGY
WITH LOWS 65-70F.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
A WELL-DEFINED COLD FRONT /WITH SHARP MSTR- PW GRADIENT/ WILL DROP
ACROSS THE REGION TUESDAY AFTERNOON AND EVENING. A CONDITIONAL
RISK FOR STRONG TO ISOLATED SEVERE STORMS WILL EXIST FROM LATE TUE
MORNING THROUGH THE AFTERNOON WITH THE PRIMARY POTNL TSTM HAZARD
BEING DAMAGING WINDS.

CLOUD COVER FROM UPSTREAM CONVECTION LKLY ONGOING AT 12Z ALONG
WITH RESIDUAL OVERNIGHT LOW STRATUS/FOG SHOULD ACT TO LIMIT
DESTABILIZATION EARLY TOMORROW. ALTHOUGH 700-500MB LAPSE RATES
WILL GENERALLY REMAIN WEAK TO POOR...THE MODELS SHOW A BELT OF
STRONGER WESTERLY MID-LVL FLOW AND DEEP LYR SHEAR. THIS SHOULD
HELP TO SUPPORT AN INCREASE IN CONVECTIVE PCPN/INTENSITY AS
RENEWED DEVELOPMENT OCCURS ALONG OUTFLOWS/DIFFERENTIAL HEATING
ZONES BY LATE MORNING INTO THE AFTERNOON...WITH SOME ORGANIZATION
INTO LINE SEGMENTS/CLUSTERS. THIS SHOULD YIELD AT LEAST AN ISOLD
DMGG WIND THREAT...WARRANTING AN UPGRADE BY SPC TO A CATEGORICAL
/SLGT/ RISK DESIGNATION. THIS HAS BEEN REFLECTED IN AN UPDATED
HWO.

EARLY CLOUDS SHOULD BREAK FOR A WARM AND HUMID DAY WITH FCST
HIGHS EXPECTED TO RANGE FROM THE MID 70S OVER THE NW TO NEAR 90
OVER THE LOWER SUSQ VLY. THE SECOND HALF OF THE PERIOD ESPECIALLY
AFTER MIDNIGHT SHOULD FEATURE A COOLER/DRYING TREND BEHIND THE
FRONT WITH PWS FALLING AOB NORMAL BY 12Z WED.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
COLD FRONT EXITING TO THE EAST TUE NIGHT ALONG WITH NORTHWEST
FLOW AROUND BUILDING HIGH PRESSURE AREA OVER OHIO VALLEY WILL
BRING A TRANSITION TO A NOTICABLY DRIER AIRMASS FOR MIDWEEK.
DAYTIME HIGHS WILL REMAIN SLIGHTLY ABOVE NORMAL...BUT LOWER
DEWPOINTS WILL MAKE IT FEEL MORE COMFORTABLE. OVERNIGHT LOWS WED
NIGHT WILL DIP TO NEAR 50F IN THE NORTHERN MTNS TO AROUND 60F IN
THE SE.

THE HIGH WILL MOVE OFF THE EAST COAST THU INTO FRI...ALLOWING MORE
HUMID AIR TO BEGIN RETURNING TO THE REGION. A SURFACE LOW SLIDES
FROM THE NORTHERN PLAINS ACROSS THE GREAT LAKES AND LIFTING INTO
S CANADA ON FRI...DRAGGING A COLD FRONT ALONG BEHIND. AS THIS
FRONT APPROACHES...AN AREA OF HIGHER PWATS /1-2"/ SURGES INTO THE
OHIO VALLEY...AND THEN INTO PA FRI NIGHT INTO SAT. AT SAME TIME A
BROAD UPPER TROUGH SAGS SOUTHWARD. THIS WILL BRING ELEVATED
CHANCES FOR SHOWERS/TSTMS STARTING FRI NIGHT IN THE NW AND
SPREADING AREAWIDE ON SAT.

BEHIND THE FRONT...AIRMASS CHANGE WILL USHER IN MUCH COOLER AND
DRIER AIR FOR LATE WEEKEND INTO EARLY NEXT WEEK. HIGHS WILL FALL
BACK ABOUT 10F...RANGING FROM THE UPPER 60S TO MID 70S. AS LARGE
HIGH PRESSURE AREA TRACKS ACROSS NEW ENGLAND...MORNING LOWS SHOULD
DIP WELL INTO THE 40S ACROSS THE NORTHERN MTNS...AND IN THE LOWER
TO MID 50S ACROSS THE SOUTH.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
18Z...CIGS/VISBYS HAVE IMPROVED TO VFR OR MVFR AS EXPECTED.
HOWEVER DESPITE A GENERAL INCREASE IN SHOWER ACTIVITY THERE IS
STILL LOW CONFIDENCE IN POINT TERMINAL IMPACTS. EVOLUTION OF
CONVECTIVE ACTIVITY AND COLLOCATION OF BEST INSTABILITY SUGGESTS
THE SRN TAFS HAVE THE BEST CHC TO SEE SCT SHOWERS OR A BRIEF TSRA
DOWNPOUR. HAVE ADDED SOME 1HR TEMPS THRU 19Z WITH SHOWERS MOVG
THRU AOO/UNV.

OTHER CONCERN WILL BE CLOUD TRENDS OVERNIGHT WITH MOIST AIRMASS
LKLY PROMOTING ANOTHER PERIOD OF LOW CIGS/FOG INTO TUE MORNING. A
COLD FRONT MOVG EWD THRU THE MIDWEST WILL ALSO BRING THE CHC FOR
SOME SHOWERS TO REACH THE NW 1/4 TO 1/3 OF THE AIRSPACE BY
EARLY TUE MORNING. THIS FRONT WILL BE A FOCUS FOR SCT-NMRS
SHWRS/TSTMS TUES AFTN-EVE AS IT MOVES SEWD ACRS CENTRAL PA. THE
RECENT GUIDANCE SUGGESTS A SLIGHTLY HIGHER PROBABILITY FOR LCL
SVR STORMS AND AT LEAST AN ISOLD THREAT FOR DAMAGING TSTM WIND
GUSTS.

OUTLOOK...
WED-THU...PATCHY AM FOG...OTHERWISE VFR.
FRI...MAINLY VFR. CHC OF PM TSTMS WEST.
SAT...VFR/MVFR WITH SCT SHWRS/TSTMS ASSOCD WITH COLD FROPA.

&&

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

&&

$$
SYNOPSIS...DEVOIR/STEINBUGL
NEAR TERM...DEVOIR/STEINBUGL
SHORT TERM...DEVOIR/STEINBUGL
LONG TERM...RXR
AVIATION...STEINBUGL


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