Skip Navigation Linkswww.nws.noaa.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service Forecast Office   NWS logo - Click to go to the NWS homepage
State College, PA banner image
 
 

Area Forecast Discussion
Latest Versions  [Current][-1][-2][-3][-4][-5][-6][-7][-8][-9]



000
FXUS61 KCTP 191951
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
351 PM EDT TUE AUG 19 2014

.SYNOPSIS...
A MASSIVE RIDGE WILL BUILD OVER EAST-CENTRAL CANADA FOR THE NEXT
WEEK. ANOTHER STRONG RIDGE WILL BUILD OVER THE SOUTHERN UNITED
STATES. SHORT-WAVES IN THE WEAK FLOW MOVING UNDER THE CANADIAN
BLOCK WILL SLOW DOWN AND WEAKEN AS THEY MOVE THROUGH OUR REGION.
THIS WILL LEAD TO A POTENTIALLY PROLONGED PERIOD OF UNSETTLED
WEATHER. BUT IT SHOULD PROTECT US FROM THE LATE SEASON HEAT
BUILDING TO OUR SOUTH.

&&

.NEAR TERM /UNTIL 9 PM THIS EVENING/...
A WEAKLY ORGANIZED BROKEN LINE OF SHOWERS AND ISOLATED
THUNDERSTORMS IS TRYING TO WORK ITS AWAY ACROSS OUR WEST-CENTRAL
COUNTIES FROM CENTRE COUNTY DOWN TO THE MARYLAND BORDER. BUMPED UP
POPS AND ADDED TEXTURE TO THE GRIDS WITH 3KM HRRR AND 4KM NAM
ESTIMATED POPS/QPF. 

RADAR SHOWS VERY LIGHT RAIN. LOCAL GAGES SHOW ABOUT 0.10 IN
WESTERN AREAS OF STATE COLLEGE. BUT SOME STREAKS ON RADAR OF 0.1
TO 0.4 INCHES. IN SOMERSET COUNTY...STRONGER CELLS SHOWS CLOSE TO
AN INCH OF ESTIMATED RAINFALL. RADAR AND HRRR IMPLY BEST CHANCE
RAIN WILL BE FROM CAMBRIA AND SOMERSET COUNTIES EASTWARD TO
HUNTINGTON AND FRANKLIN COUNTY AS THE STRONGEST ELEMENTS HEAD
SLOWLY EAST.

THE 3KM AND 4KM MODELS IMPLY MOST OF THIS CONVECTION DIES OFF A
FEW HOURS EITHER SIDE 6 PM.

&&

.SHORT TERM /9 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SREF AND NAM CONTINUE TO SHOW CHANCE TO SLIGHT CHANCE OF SHOWERS
OVERNIGHT. MOST AREAS RAIN FREE IN HRRR AFTER 0000 UTC TONIGHT
THROUGH 0600 UTC.

BUT THE HRRR DOES SHOW OVERNIGHT CONVECTION IN THE MIDWEST MOVING
INTO WESTERN PA AFTER 0600 UTC. CHANCE RAIN WILL CLEARER INCREASE
BEFORE SUNRISE IN WESTERN AREAS.

THE SURGE OF CAPE AND PW INTO WESTERN PA IN THE SREF AND
NAM...SIMILAR TO OLDER GEFS/GFS IMPLY SOME MORE ORGANIZED RAIN
POSSIBLE ON WEDNESDAY. USED A BLEND TO GET THE POPS AND THE 12KM
NAM TO ADD SOME TEXTURE TO CONVECTION AND RAIN AREA THAT APPEARS
TO BE POISED TO MOVE WEST TO EAST ACROSS THE REGION WEDNESDAY.

THE SREF POPS/PDF IMPLIES SHOWERS COMING INTO WEST AROUND 1500 UTC
AND MOST OF CENTRAL TWO THIRDS OF REGION BY LATE EVENING. SREF IS
KIND OF OPTIMISTIC SOUTHEAST PA COULD HAVE YET ANOTHER MOSTLY
RAIN FREE DAY WEDNESDAY.  

THE KEY FEATURES ARE THE RETROGRADING RIDGE OVER EASTERN CANADA
WHICH IS TAKING THE UMPH OUT OF THE SYSTEMS CUTTING UNDER THIS
FEATURE. IN MOST MODELS THE NEAR 1SD ABOVE NORMAL PW SURGES WEAKEN
AS THE MOVE INTO PA. THUS MORE OPTIMISTIC...SREF-LIKE IN THE WEST
THAN THE EAST WITH RAINFALL AND NOT REALLY CONFIDENT GOING LIKELY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...

THE WEAKENING RIDGE OVER EASTERN CANADA WILL ALLOW FOR DIVERGENT
FLOW AS THE UPPER LEVEL LOW SLOWLY MOVES EASTWARD. DAYTIME
HEATING...DECREASING PRESSURE...MOIST SOUTHEASTERLY SFC FLOW...AND
WEST TO NORTHWESTERLY FLOW ALOFT SHOULD ALLOW FOR ENOUGH
SHEAR...FOR CHANCE TO LIKELY POPS EARLY WEDNESDAY EVENING. CAPE
VALUES ARE LOW...WITH AN AVG OF 500-1K J/KG THROUGHOUT MOST OF
CENTRAL PA. SO SCATTERED SHOWERS AND THUNDERSTORMS REMAIN POSSIBLE
EARLY WEDNESDAY EVENING. THESE WILL SLOWLY FADE AS THE EVENING
CONTINUES.

THURSDAY LOOKS LIKE ANOTHER UNSETTLED DAY...AS UPPER LOW MAKES
IT/S CLOSEST PASS TO PA...TRACKING ACROSS UPSTATE NY...WITH THE
850MB LOW MOVING THROUGH PA. COOL TEMPS ALOFT...COMBINED WITH
DIURNAL HEATING...SHOULD YIELD NUMEROUS SHRA AND TSRA BY THE
AFTERNOON. HAVE CONTINUED POPS IN THE LIKELY CATEGORY BASED ON 12Z
OPERATIONAL AND GEFS OUTPUT. DUE TO THE CHANGING POSITION AND
TIMING OF THE LOW...HAVE SLIGHTLY LOWERED POPS ALONG THE SOUTHERN
HALF OF THE CWA. THE SOUTHERLY LL JET AND PLUME OF HIGH PWATS WILL
HAVE PASSED NE OF THE AREA THURSDAY...LIMITING THE THREAT OF ANY
HVY RAINFALL. MODEL BLENDED QPF IS IN THE QUARTER TO HALF INCH
RANGE THURSDAY. BEFORE THE LOW PASSES...TEMPS COULD REACH UP TO
THE LOW 80S. AFTER THURSDAY/S NUMEROUS SHOWERS AND THE ADVECTION
OF COOLER TEMPS ALOFT...HIGH TEMPS SHOULD DROP BELOW NORMAL FOR
AUGUST...WITH MAXES MAINLY IN THE 70S THROUGH THE END OF THE WORK
WEEK INTO THE WEEKEND.

LATEST MED RANGE GUIDANCE POINTING TOWARD DRIER WX FRIDAY INTO
EARLY NEXT WEEK...AS SUBTROPICAL HIGH IS PROGGED TO EDGE TOWARD
THE REGION FROM THE MIDWEST. DAILY RING OF FIRE CONVECTION ON NE
PERIPHERY OF THIS RIDGE WILL THREATEN WESTERN PA DURING THE 
FRI-SUN TIME FRAME...WHILE EASTERN PA IS LIKELY TO REMAIN DRY.
DESPITE APPROACH OF UPPER RIDGE...NO BIG WARM UP EXPECTED...AS
LARGE SFC HIGH OVR THE CANADIAN MARITIMES WILL CIRCULATE AN
EASTERLY FLOW INTO CENTRAL PA. THERE MAY BE ISSUE WITH AM LOW
CLOUDS/FOG DUE TO THE EXPECTED MOISTLY SERLY FLOW OVR THE AREA.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
RADAR SHOWS SOME ORGANIZED SHOWERS AND THUNDERSTORMS FROM NEAR
KFIG SOUTH TO THE MARYLAND BORDER. THESE SHOWERS AND STORMS WILL
SLOWLY MOVE EASTWARD THIS AFTERNOON. AREAS OF MVFR AND LOCALLY IFR
ARE POSSIBLE ALONG THE LINE AND WITHIN THE SHOWERS AND
THUNDERSTORMS. 

MODELS ALL SUGGEST POPCORN SHOWERS POSSIBLE OVER MOST OF CENTRAL
PA AND THE MORE ORGANIZED ACTIVITY OVER THE SOUTHERN HALF OF THE
STATE THROUGH THIS EVENING. 

THINGS SETTLE DOWN OVERNIGHT...MORE PATCHY FOG AND LOW CLOUDS.SO
MORE AREAS OF MVFR AND IFR. 

WEDNESDAY WILL SEE RAIN AND SHOWERS LIKELY IN WESTERN PA BY MID-
LATE MORNING SLOWLY SPREADING EAST. VFR IN EAST BUT AREAS MVFR
LIKELY IN AM FOG AND THEN SHOWERS IN WESTERN AREAS.

OUTLOOK...

TUE...MAINLY VFR...WITH SHRA/TSRA POSSIBLE.
WED...MORNING FOG/LOW CLOUDS SHRA/TSRA LIKELY WEST CHANCE EAST.
THU-FRI...MORNING FOG CHANCES EACH DAY. OVERALL VFR...BUT
INCREASING CHANCES OF MAINLY AFTERNOON SHRA/TSRA AND ASSOCIATED
RESTRICTIONS. SAT...MAINLY VFR. STILL CHANCE OF SHRA...BUT
DECREASING CHANCES.

&&

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

&&

$$
SYNOPSIS...
NEAR TERM...GRUMM
SHORT TERM...GRUMM
LONG TERM...CERU/FITZGERALD 
AVIATION...GRUMM



National Weather Service
Disclaimer Privacy Policy