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Area Forecast Discussion
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000
FXUS61 KCTP 230029
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
829 PM EDT MON SEP 22 2014

.SYNOPSIS...
A LARGE AREA OF HIGH PRESSURE OVER THE MIDWEST...WILL BUILD EAST
ACROSS THE MID ATLANTIC REGION TUESDAY BEFORE DRIFTING OVER THE
NEW ENGLAND STATES FOR THE LATTER HALF OF THE WEEK. THIS DOMINANT
WEATHER FEATURE WILL PROVIDE GENERALLY FAIR AND COOL WEATHER FOR
THE ENTIRE WEEK.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
HIGH PRESSURE WILL BUILD IN OVERNIGHT...EVENTUALLY LEADING TO THE
GRADIENT SLACKENING UP AND THE WIND DIMINISHING TO LIGHT AND
VARIABLE. FORECAST SOUNDINGS INDICATE THAT THE LOW LEVEL INVERSION
SHOULD LOWER AND WEAKEN...ALLOWING DRIER AIR TO MIX DOWN AND SCOUR
OUT THE LOW CLOUD SHIELD THAT IS STILL RATHER EXTENSIVE AS OF
SUNDOWN. CLOUDS CLOSER TO THE LAKES MAY TALE MUCH OF THE
OVERNIGHT TO ERODE...WHICH SHOULD HELP MITIGATE FROST PROBLEMS.

LOW TEMPS EARLY TUESDAY WILL REACH FROSTY LEVELS ACROSS THE
HIGHER TERRAIN OF SOMERSET COUNTY...WHERE A FROST ADVISORY WAS
POSTED FROM 07-13Z TUESDAY. ELSEWHERE...PATCHY FROST IS POSSIBLE
FOR RURAL VALLEYS...EXCEPT FOR THE LOWER SUSQ VALLEY. LOWS WILL BE
IN THE U30S TO AROUND 40F IN MOST LOCATIONS THROUGHOUT THE CENTRAL
RIDGE AND VALLEY REGION...WITH LOWER 40S IN THE LARGER SERN PENN
METRO AREAS SUCH AS YORK...HARRISBURG...AND LANCASTER.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
HIGH PRESSURE WILL BUILD EAST FROM THE OHIO NE UP THE OHIO VALLEY
AND BECOME CENTERED RIGHT OVER THE REGION TUESDAY AFTERNOON.

AFTER SOME LOCALLY DENSE RIVER VALLEY FOG AND PATCHY FROST IN A
FEW OF THE COLDER SPOTS EARLY TUESDAY...EXPECT ABUNDANT SUNSHINE
AND LIGHT WIND FOR THE LATE MORNING AND AFTERNOON HOURS.

TUESDAY WILL BE A MUCH MILDER DAY WITH TEMPS RISING ABOUT 25F
DURING THE DAY...AND REACHING ABOUT 10F MILDER THAN MONDAY/S HIGHS 
IN THE NW - BUT STAYING SIMILAR TO MONDAY IN THE LOWER SUSQ.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
STRONG HIGH PRESSURE WILL DOMINATE THE WEATHER PATTERN THROUGH THE
REST OF THE WEEK AND INTO EARLY NEXT WEEK WITH HIGHER THAN NORMAL
MSLP ANOMALIES OVER THE REGION. THE MODELS ARE IN FAIR AGREEMENT
THROUGH MOST OF THE PERIOD...THOUGH THEY DIVERGE THIS WEEKEND AND
THROUGH NEXT WEEK. HOWEVER...ALL SOLUTIONS KEEP THE REGION DRY
DUE TO A BLOCKING 500 HPA ANTICYCLONE AND DRY MIDLEVELS.

THE BIG QUESTION IS THE EXTENT OF DIURNAL VALLEY FOG. EXPECT
PATCHY FOG WEDNESDAY AND THURSDAY MORNINGS WITH DENSE FOG AND LOW
CLOUDS POSSIBLE. THE GFS AND EC AND CANADIAN MODELS DIVERGE BUT
THE NEXT CHANCE FOR PRECIPITATION SHOULD/T BE UNTIL MID TO LATE
NEXT WEEK.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
23/00Z...LATEST IR STLT DATA IS SHOWING A MUCH SLOWER CLEARING
TREND THAN EARLIER ANTICIPATED. THEREFORE HAVE PROLONGED MVFR CIGS
AT BFD/JST AND CUT BACK ON REDUCED VISBYS IN FOG TOWARD DAYBREAK
GIVEN LOWER CONFIDENCE. THE FOG DEVELOPMENT IS CONDITIONAL AND
PREDICATED ON SKC WHICH NOW LOOKS TO BE IN JEOPARDY ESP OVER THE
NW 1/2 TO 1/3 OF THE AIRSPACE...AS THE LLVL MSTR GETS TRAPPED
BENEATH SUBSIDENCE INVERSION ASSOCD WITH HP BUILDING EWD FROM THE
OH VLY. AS SUCH...CONFIDENCE IN FOG IS LOW(ER) BUT KEPT VCFG
MENTION FOR CONTINUITY. ANY EARLY MORNING FOG OR LOW CLOUD
RESTRICTIONS WILL GIVE WAY TO ABUNDANT VFR FLYING BY 15Z TUE WITH
FAIR WX CU LKLY IN THE AFTN.

HP GENERALLY REMAINS IN CONTROL OF THE REGIONAL PATTERN INTO THE
WEEKEND. HOWEVER...IT LOOKS LIKE A SETBACK MAY OCCUR LATER WED
INTO THURS AS AN INVERTED TROUGH SETS UP ALONG THE ERN SEABOARD
AND EASTERLY FLOW DEVELOPS SOUTH OF STG HP IN THE GULF OF MAINE. 

OUTLOOK...
WED...PATCHY FOG IN THE MORNING...OTHERWISE VFR. 
THU...LOW CIGS AND AREAS OF -RA/DZ PSBL. 
FRI-SAT...PATCHY FOG IN THE MORNING...OTHERWISE VFR. 

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY FROM 3 AM TO 9 AM EDT TUESDAY FOR PAZ033.

&&

$$
SYNOPSIS...LA CORTE/LAMBERT
NEAR TERM...LA CORTE/LAMBERT
SHORT TERM...LAMBERT
LONG TERM...GRUMM/CERU
AVIATION...STEINBUGL



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