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000
FXUS61 KCTP 180515
AFDCTP

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

.SYNOPSIS...
A RIDGE OF HIGH PRESSURE FROM THE CANADIAN MARITIMES DOWN THROUGH
THE CAROLINAS WILL KEEP FAIR AND DRY WEATHER ACROSS MOST OF THE
REGION THROUGH FRIDAY. A WEAK COLD FRONT WILL BRUSH NORTHWESTERN
PENNSYLVANIA LATE TOMORROW AND TOMORROW NIGHT. ANOTHER AREA OF
HIGH PRESSURE WILL BUILD EAST INTO THE COMMONWEALTH FOR THE
WEEKEND. TEMPERATURES WILL MODERATE THIS WEEKEND AND RISE ABOVE
NORMAL BY EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
SOME LOW CLOUDS MOVED ACROSS THE SOUTHERN AREAS AND APPEARED TO
HAMPER THE FROST ADVISORY BUT WE HAVE HAD SOME CLEARING AS THIS
FEATURE MOVED WEST AND NOW HAVE REPORTS OF TEMPERATURES IN THE
34-37F RANGE THOUGH BIGGER CITIES STILL NEAR 40. SO WILL KEEP
FROST ADVISORY IN EFFECT AS SOME LOCATIONS NOW BELOW THE MAGIC 36F
SHELTER HEIGHT. WINDS HAVE LUFT A BIT TOO.

MOST OF WEST IS CLEAR AND TEMPERATURES RUNNING WARMER THAN LAST
NIGHT. REALLY MASSIVE 1040 HPA HIGH OVER NEW ENGLAND WITH +3 SIGMA
PRESSURE ANOMALIES HAS KEPT COLD AIR IN AT LOW LEVELS BUT NOW
BRINGING SOME MARINE LAYER AIR INTO SOUTHEAST.

SATELLITE IMAGERY SHOWS THE SYSTEM TO OUR WEST WHICH WILL TRY TO
MOVE INTO THIS LARGE ANTICYCLONE. SREF SHOWS SOME CHANCE POPS AS
THE ANEMIC FRONT PUSHES INTO PA LATER TODAY AND THIS EVENING. KEPT
POPS IN NORTHERN TIER AND USED 3-HOUR SREF PROBABILITY DISTRIBUTION
FUNCTION "POPS" TO SHOW PROGRESSIVE EVOLUTION. I LOWERED THE
VALUES AS THESE ARE NOT STATISTICAL POPS AS IN MOS BUT A
DISTRIBUTION FUNCTION IN A SYSTEM WITH A LOW QPF WET BIAS.

HARD TO GET EXCITED ABOUT A TROUGH THAT HAS POSITIVE PRESSURE
ANOMALIES!

ANY RAIN WOULD BE LIGHT AND THE ANTICYCLONE BEHING THIS
SYSTEM AT 1030 HPA IS A BIT WEAKER. ITS A GOOD TIME FOR
ANTICYCLONES.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
THE MEAN BLYR FLOW VEERS A BIT MORE TO THE SSE OR SOUTH DURING
THE DAY FRIDAY...WHICH WILL HELP AN ILL-DEFINED WARM FRONT LIFT
NORTH ACROSS THE REGION AND INTO NEW YORK STATE.

A BROAD...NEARLY NORTH-SOUTH AXIS OF LLVL MOISTURE CONVERGENCE
AND HIGHER DEWPOINTS WILL HELP TO CREATE MORE IN THE WAY OF STRATO
CU...THAN THE NEARLY NON-EXISTENT AMOUNTS THAT WE/VE SEEN IN THE
UNUSUALLY COLD...AND BONE-DRY AIRMASS THE PAST FEW DAYS.

OTHERWISE...THE LLVL RIDGE AXIS STAYS IN PLACE ALONG THE MID
ATLANTIC PIEDMONT AND HELPS TO DEFLECT A WEAK NORTHERN STREAM
SYSTEM TO OUR NORTH. A SIGNIFICANTLY STRONGER SRN STREAM STORM
WILL ALSO BE HELD AT BAY WELL TO THE SOUTH OF THE AREA. A FEW
LIGHT SHOWERS MAY GRAZE THE NWRN COS LATE FRIDAY...OR
FRIDAY NIGHT.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
THE 17/12Z MEDIUM RANGE MODEL AND ENSEMBLE GUIDANCE HAS COME INTO
MUCH BETTER AGREEMENT ON THE LARGE SCALE PATTERN EVOLUTION ACROSS
THE LOWER 48 THIS PERIOD...SUPPORTING INCREASING CONFIDENCE IN
THE FORECAST. THE MAIN THEME FOR CENTRAL PA OVER THE NEXT 7+ DAYS
WILL BE A DRY AND RELATIVELY BENIGN WEATHER PATTERN...WITH NO
SIGNIFICANT RAIN-PRODUCING SYSTEMS ON THE HORIZON. THIS SHOULD
CONTRIBUTE TO INCREASING FIRE WEATHER CONCERNS. TEMPERATURES WILL
MODERATE THROUGH NEXT WEEK...TRENDING WARMER WITH THE ODDS FAVORING
A TILT TOWARD THE WARMER-SIDE OF LATE APRIL CLIMATOLOGY.

NRN STREAM SHORTWAVE TROUGH AND SFC COLD FRONT PUSHING EASTWARD
FROM THE GREAT LAKES REGION INTO THE NORTHEAST STATES WILL BRING
SCT...VERY LIGHT RAIN SHOWERS TO NW/N-CENTRAL PA LATE FRIDAY
NIGHT INTO EARLY SATURDAY MORNING. LIMITED RETURN FLOW AND
RELATIVELY COOL/DRY AIRMASS IN PLACE AHEAD OF THIS SYSTEM SHOULD
LIMIT QPF AMTS TO AOB 0.10 INCH. MODEL CONSENSUS KEEPS PCPN
ASSOCIATED WITH CLOSED SRN STREAM LOW TO THE SOUTH OF THE
AREA...WITH CANADIAN HIGH PRESSURE REGAINING CONTROL OF THE
SYNOPTIC PATTERN THROUGH THE REMAINDER OF EASTER WEEKEND.
GUIDANCE TEMPERATURES APPEAR MARGINAL FOR FROST SUN-MON MORNING
ACROSS THE LOWER SUSQ VLY WHERE THE GROWING SEASON IS OFFICIALLY
UNDERWAY.

THE BEST OPPORTUNITY/HIGHEST PROBABILITY FOR APPRECIABLE RAINFALL
/0.25 TO 0.50 INCH AMOUNTS/ OVER THE NEXT 7 DAYS WILL LIKELY COME
ON TUESDAY...WITH SLIGHTLY BETTER MOISTURE IN PLACE AHEAD OF AN
APPROACHING SHORTWAVE TROUGH AND SFC COLD FRONT. THE ECMWF IS MORE
AGGRESSIVE IN BRINGING HEIGHT FALLS INTO THE NORTHEAST ON DAY
7/WED EVENTUALLY CLOSING OFF A 500MB LOW NEAR SOUTHERN NEW ENGLAND.
MEANWHILE THE GFS/GEFS ARE NOT AS STRONG AND GENERALLY MORE
PROGRESSIVE ALOFT...WHICH LEADS TO FASTER HEIGHT RISES HEADING
INTO THE SECOND HALF OF NEXT WEEK. THE SENSIBLE WEATHER HIGHLIGHT
IS PROBABLY A RELATIVE MINIMUM IN DAYTIME HIGH TEMPERATURES FOR
NEXT WEDNESDAY WITH BOTH MODELS/EFS DEPICTING A WEAK NEGATIVE
H5-H7 ANOMALY INVOF THE NEW ENGLAND COAST.

UPPER TROUGH/CLOSED LOW IS PROGGED TO MIGRATE EWD ACROSS THE NRN
ROCKIES INTO THE UPPER MIDWEST WED-FRI. DOWNSTREAM RIDGE AXIS OVER
THE CENTRAL PLAINS/MS VLY/MID-SOUTH SHOULD REACH THE EAST COAST
BY THE END OF NEXT WEEK. THIS SUGGESTS A WARMING TREND FOLLOWING
THE BRIEF COOL-DOWN MIDWEEK WITH MAX TEMPS POSSIBLY HEADING BACK
TO/OR ABOVE 70F.

&&

.AVIATION /05Z FRIDAY THROUGH TUESDAY/...
A LAYER OF SHALLOW/BKN MVFR-LOW END VFR STRATOCU WILL BE SLIDING
IN FROM THE SE OVERNIGHT ACROSS THE LOWER SUSQ VALLEY
AIRFIELDS...AND REACHING THE CENTRAL MTNS EARLY TOMORROW MORNING.

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.

CHANCE FOR LIGHT RAIN TO IMPACT MAINLY NW LATE FRIDAY AFTERNOON OR
FRIDAY NIGHT WITH LOW PROB OF RESTRICTIONS. VFR ELSEWHERE.

OUTLOOK...
FRI...GENERALLY VFR. AREAS OF MVFR CIGS POSS ACROSS CENTRAL AND SE
PA EARLY.

FRI NIGHT-SAT...REDUCED CIGS/VSBYS POSS WITH CHANCE OF LIGHT RAIN
SHOWERS /MAINLY NW HALF/.

SUN-MON...NO SIG WX.

TUE...A FEW...TO SEVERAL-HOUR PERIOD OF MVFR CIGS 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...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...DANGELO/LAMBERT
LONG TERM...STEINBUGL
AVIATION...LAMBERT/CERU