Area Forecast Discussion
Issued by NWS State College, PA

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000
FXUS61 KCTP 180849
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
449 AM EDT FRI APR 18 2014

.SYNOPSIS...
A MASSIVE SURFACE AND 500 HPA ANTICYCLONE OVER THE WESTERN
ATLANTIC WILL SLOWLY WEAKEN OVER THE NEXT SEVERAL DAYS AS A RIDGE
TO OUR WEST MOVES OVER OUR REGION. THE RESULT IS ABOVE NORMAL
HEIGHTS INTO EARLY NEXT WEEK. A TROUGH IN THE NORTHERN STREAM
SHOULD WEAKEN THE RIDGE AND COULD TRIGGER SHOWERS TUESDAY-
WEDNESDAY BUT YET ANOTHER RIDGE MOVES IN QUICKLY BEHIND THIS
SYSTEM BY NEXT THURSDAY. NOT A GOOD PATTERN FOR SIGNFICANT
RAINFALL AND NEAR NORMAL TEMPERATURES MOST OF THE PERIOD.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE SLOWLY RETREATING 1040HPA HIGH IS PRODUCING LOW-LEVEL EASTERLY
FLOW. THUS...THE LOW CLOUDS AND MARINE LAYER HAVE MOVED ACROSS
LANCASTER AND LEBANON COUNTIES. THE LEADING EDGE IS NO INTO YORK
AND DAUPHIN COUNTIES. THE WINDS DIED AND IT REMAINED CLEAR ENOUGH
SUCH THAT TEMPERATURES WERE A FEW DEGREES OTHER SIDE OF FREEZING.
WE KEPT THE FROST ADVISORY UP DESPITE THE APPROACHING CLOUDS.

AFTER A COLD START SHOULD TURN OUT TO BE A PRETTY GOOD DAY.
SATELLITE IMAGERY SHOWS CLOUDS IN THE SOUTHERN STREAM AND NORTHERN
STREAM WILL PRODUCED MOSTLY CLOUDY DAY. LEANED TOWARD A NAM/SREF
BLEND IN THE POPS WHICH INDICATED LATER AFTERNOON LIGHT RAIN
SHOWERS ALONG THE NY BORDER. LOWERED THE POPS BELOW THE ENSEMBLE
FREQUENCY DISTRIBUTION. SREF IS TOO WET WITH LOW QPF SO LOWERED
VALUES. MOST AREAS WILL REMAIN RAIN FREE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
THE ONLY RAIN POTENTIAL IS IN THE NORTHWEST 3 HOURS EITHER SIDE OF
ABOUT 7 PM. IT SHOULD BE QUITE LIGHT. AS IN PREVIOUS PERIOD USED
BLEND OF SREF AND NAM FOR FREQUENCY TO MAKE A POP.

THE WEAK FRONT AHEAD OF THE APPROACHING ANTICYCLONE WILL USHER IN
SOME DRY AIR WITH -1 SIGMA PW ANOMALIES. THIS SHOULD HELP REDUCE
CLOUDS. SHOULD BE MOSTLYRAIN EVENT. HEIGHTS SHOULD DROP SLIGHTLY BELOW NORMAL
WEDNESDAY AND 850 HPA TEMPS DROP TO JUST BELOW NORMAL.

HEIGHTS AND TEMPERATURES REBOUND BACK TOWARD NORMAL THURSDAY AND
FRIDAY COULD BE A RELATIVELY WARM DAY. UNCERTAINTY GROWS IN
FORECAST AND SOME ENSEMBLE MEMBERS SHOW SURGE OF MOISTURE IN WARM
AIR AHEAD OF YET ANOTHER POTENTIAL TROUGH. THE CHANCE OF RAIN
SHOULD GRADUALLY INCREASE IN THE FRIDAY OR SATURDAY TIME FRAME.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
A LAYER OF SHALLOW/BKN MVFR-LOW END VFR STRATOCU WILL BE SLIDING
INTO SUSQ VALLEY AIRFIELDS FROM THE SE OVERNIGHT...AND ULTIMATELY
EDGING INTO PORTIONS OF THE CENTRAL MTNS JUST BEFORE SUNRISE.

MAINLY SUNNY SKIES WILL CONTINUE WITH SOUTHEAST TO SOUTH-SOUTHEAST
WINDS AVERAGING TO 8-12 KTS WITH OCCASIONAL GUSTS AROUND 20
KTS. THE WIND WILL SUBSIDE BY 00Z.

DURING THE DAY ON FRI...CHANCE FOR LIGHT RAIN TO IMPACT MAINLY NW
LATE IN THE AFTERNOON INTO THE EVE WITH LOW PROB OF RESTRICTIONS.
VFR ELSEWHERE. LI SUNNY AND WITH 850 HPA TEMPS IN THE +3 TO
0C RANGE EXPECT NEAR NORMAL HIGH TEMPERATURES. 2M TEMPS SUPPORT
WIDESPREAD HIGHS IN THE 50S TO AROUND 60.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...

AT THIS TIME THE ENSEMBLES SUGGEST THE BEST CHANCE OF RAIN IN THE
NEXT WEEK WILL BE IN THE TUESDAY-WEDNESDAY TIMEFRAME. GEFS FAVORS
RAIN AHEAD OF THE DEEPENING TROUGH AND FRONTAL SYSTEM MAINLY
TUESDAY. BUT TIMING COULD CHANGE AND SOME CHANCE LINGERING INTO
EARLY WEDNESDAY.

THE COMING 7 DAYS IN GENERAL...
SATURDAY NIGHT INTO SUNDAY THE REGION WILL BE DOMINATED BY A
STRONG ANTICYCLONE. SHOULD BE GENERALLY FAIR DRY WEATHER. THE
ANTICYCLONE WEAKENS MONDAY BUT STILL IN A RIDGE. VERY WEAK FLOW
AHEAD OF THE APPROACHING FRONTAL BOUNDARY. THERE IS NO PRESSURE
GRADIENT OVER MOST OF THE EASTERN UNITED STATES MONDAY IN THE GEFS
OR NAEFS.

A SHORTWAVE AND FRONT SHOULD TRIGGER SHOWERS AND RAIN TUESDAY INTO
EARLY WEDNESDAY. TROUGH OVER A RIDGE AND NO BIG PW SURGE...NOT A
BIG GHT SOUTHEAST WINDS WILL SHIFT TO THE SOUTH AND
THEN SW THROUGH THE DAY...WITH INCREASES TO 5-10 KTS WITH GUSTS TO
AROUND 15 KTS.

OUTLOOK...
TONIGHT-SAT...REDUCED CIGS/VSBYS POSS WITH CHANCE OF LIGHT RAIN
SHOWERS MAINLY NW HALF. VFR ELSEWHERE.

SUN-MON...NO SIG WX.

TUE...SEVERAL-HOUR PERIOD OF MVFR CIGS POSS WITH BRIEF MVFR VSBYS
IN SHOWERS ACCOMPANYING A COLD FRONTAL PASSAGE.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY UNTIL 8 AM EDT THIS MORNING FOR PAZ057-059-
063>066.

&&

$$
SYNOPSIS...GRUMM
NEAR TERM...LA CORTE
SHORT TERM...DANGELO/LAMBERT
LONG TERM...GRUMM
AVIATION...RXR


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