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Area Forecast Discussion
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000
FXUS61 KCTP 050246
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1046 PM EDT FRI SEP 4 2015

.SYNOPSIS...

HIGH PRESSURE WILL ENSURE FAIR AND MAINLY DRY WEATHER FOR LABOR
DAY WEEKEND WITH ABOVE NORMAL WARMTH AND JUST THE CHANCE OF AN
AFTERNOON OR EVENING POP-UP SHOWER OR THUNDERSTORM.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...

AS THE SURFACE AND UPPER LEVEL HIGH SLIDES SOUTH ALONG THE NEW
ENGLAND COAST...IT IS FORCING A DEEP EASTERLY FLOW INTO THE AREA.
WEAK LOCAL FORCING...RESIDUAL INSTABILITY AND A GENERAL UPSLOPE
COMPONENT TO THE LOW LEVEL FLOW ARE ALL COMBINING TO KEEP SOME
SCATTERED SHOWERS AND THUNDERSTORMS FLOATING AROUND IN A RATHER
DISORGANIZED FASHION AS OF LATE EVENING.

THE HRRR KEEPS TRYING TO ORGANIZE A SMALL MCS WHICH IT TRACKS
THROUGH THE SOUTH CENTRAL MOUNTAINS BETWEEN ABOUT 5 AND 11Z. THIS
SEEMS OVERDONE AND WILL MORE LIKELY BE ISOLATED LEFT OVER
ACTIVITY... GIVEN THE NEGATIVE TREND IN OBSERVED CAPE AND THE
NORMAL DIURNAL DIE OFF TIME...AND EVEN COULD BE PORTRAYING AN
INCREASE IN LOW CLOUDS/MOISTURE THAT SHOULD START ADVECTING WEST
IN THE MARITIME FLOW.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...

FOR SATURDAY MODEL MID LEVEL TEMPS ARE EXPECTED TO INCREASE TO
VALUES CLOSER TO WHAT WE NORMALLY SEE ACT AS AN EFFECTIVE CAP IN
THE LOCAL AREA. BETWEEN THAT AND MORE IN THE WAY OF LOW
CLOUDINESS...WE SHOULD BE COOLER IN THE LOW LEVELS AND WARMER
ALOFT WHICH WILL EQUATE TO LESS INSTABILITY AND A SMALLER CHANCE FOR
SHOWERS. THE BEST CHANCE FOR AN ISOLATED STORM WILL BE OVER
WESTERN AREAS DURING THE LATTER HALF OF THE DAY.

HIGHS WILL BE A FEW DEGREES COOLER THAN PREVIOUS DAYS AND
DEWPOINTS WILL EVEN NUDGE DOWN A BIT AS LOWER DEWPOINTS START TO
ADVECT IN FORM THE NORTHEAST.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
A RATHER LARGE AREA OF HIGH PRESSURE AT THE SFC...AND A SLOWLY 
FLATTENING UPPER RIDGE OVER THE EASTERN U.S...SHOULD MAINTAIN DRY 
WEATHER SATURDAY NIGHT THROUGH MONDAY. PRECIPITABLE WATER VALUES 
WILL RANGE FROM BELOW NORMAL AND ONLY AROUND ONE-HALF OF AN INCH 
ACROSS FAR NERN PENN...TO SLIGHTLY ABOVE NORMAL ALONG THE SE SHORE 
OF LAKE ERIE SUNDAY SATURDAY NIGHT INTO SUNDAY NIGHT. A FEW SHOWERS 
OR EVEN A BRIEF TSRA COULD BRUSH OUR FAR NW ZONES DURING THIS 
INITIAL 24 HOURS OF THE LONG TERM PERIOD...BUT POPS WILL BE LESS 
THAN 25 PERCENT.   
 
AN INITIAL...WEAK...COLD FRONT WILL SLIDE SLOWLY TO THE ESE FROM THE 
GREAT LAKES/MIDWEST STATES. THIS FEATURE COULD BRING SOME ISOLATED 
SHRA/TSRA TO OUR NW ZONES BEGINNING TUESDAY AFTERNOON AND EVENING.

A SLOWLY AMPLIFYING...BROAD TROUGH FROM THE NRN PLAINS THROUGH THE 
NE U.S. WEDNESDAY AFTERNOON INTO NEXT WEEKEND WILL PUSH A
SECOND...STRONGER CFRONT EAST ACROSS THE COMMONWEALTH WEDNESDAY
NIGHT AND THURSDAY. 

THIS PATTERN TRANSITION WILL BRING A FEW OPPORTUNITIES FOR
SHOWERS AND THUNDERSTORMS...ALBEIT MAINLY OF THE SCATTERED
AFTERNOON AND EVENING VARIETY.

12Z GEFS AND 12Z EC ARE IN GOOD AGREEMENT ON THE LOCATION OF THIS
TROUGH AXIS /FROM LAKE SUPERIOR TO THE MID MISS VALLEY AT 00Z
SAT/...THOUGH AS ONE WOULD EXPECT...THE ENSEMBLE MEAN DAMPENS OUT
THE AMPLITUDE OF THE TROUGH COMPARED TO THE EC.

DETAILS IN THE TIMING OF ANY SPECIFIC SHORTWAVES ROTATING THROUGH 
THIS AMPLIFYING TROUGH ARE SIMPLY TOO MUDDY AT THIS TIME RANGE.

ONE THING MORE CERTAIN IN THIS MEDIUM RANGE FORECAST IS THE COOLING 
TEMPS FOR THE LATTER HALF OF THE WEEK AND NEXT WEEKEND...WHEN BOTH 
MAX AND MIN TEMPS COULD BE UP TO SEVERAL DEG F BELOW NORMAL 
/ESPECIALLY OVER THE NRN AND WESTERN MTNS OF THE STATE...WHERE MORE 
CLOUDS AND COOLER TEMPS ALOFT WILL BE FOUND/.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
THE LOSS OF DAYTIME HEATING/INSTABILITY SHOULD LEAD TO GRADUAL
WEAKENING AND DISSIPATING TREND IN CONVECTIVE ACTIVITY THROUGH
LATE EVENING. THE COSPA/HRRR GUIDANCE IS CURIOUSLY AGGRESSIVE IN
MAINTAINING CONVECTIVE PCPN OVER THE SOUTH-CENTRAL AIRSPACE INTO
LATE TONIGHT...AND HAVE DISCOUNTED THIS FOR NOW AS BLYR BECOMES
MORE STABLE WITH TIME. 

THE MAIN CONCERN OVERNIGHT WILL BE DEVELOPING LOW CLOUDS AND FOG.
A MOIST LOW-LEVEL FLOW FROM THE SOUTHEAST BEHIND THE BACKDOOR
COLD FRONT WILL LIKELY PRODUCE MVFR TO IFR CONDS ACROSS MUCH OF
THE AIRSPACE INTO EARLY SATURDAY MORNING. CIGS MAY BE SLOW TO LIFT
AFTER DAYBREAK BUT EXPECT WIDESPREAD VFR TO RETURN BY THE AFTN. 

SFC HIGH PRESSURE WILL BUILD INTO THE REGION FOR THE REST OF THE
WEEKEND AND PROVIDE MAINLY VFR FLYING THRU EARLY NEXT WEEK.

OUTLOOK...

SUN-TUE...PATCHY FOG IN THE MORNING...OTHERWISE VFR.

WED...COLD FROPA WITH SCT SHRA/TSRA.

&&

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

&&

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



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