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Area Forecast Discussion
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000
FXUS61 KCTP 042231
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
631 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/...

SAME SCENARIO PLAYING OUT THIS EVENING AS THE LAST SEVERAL...WITH
DIURNALLY FORCED CONVECTION...THIS TIME MAINLY TREKKING EAST TO
WEST...SCATTERED ABOUT THE REGION. THE SHOWERS AND STORMS WILL
GRADUALLY LOSE VIGOR OVER THE NEXT SEVERAL HOURS AS WE LOSE
HEATING. UNTIL THEN...SOME OF THE STRONGER SLOW MOVING STORMS
COULD PRODUCE GUSTY WINDS...DOWNPOURS AND POSSIBLE LOCALIZED
FLOODING.

INTERESTING TO NOTE THE HRRR REALLY LIGHTS THINGS UP AFTER 00Z
OVER THE SOUTH-CENTRAL MOUNTAINS. THIS SEEMS COUNTERINTUITIVE
GIVEN THE WEAK DIURNAL FORCING. 

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
CONVECTION ONGOING AT THE START OF THE PERIOD MAY BE THE LAST OF
THE RAIN FOR A FEW DAYS. EXPECT SHRA/TSRA TO WANE THROUGH THE
EVENING. THE INTERESTING/CHALLENGING PART OF THIS FORECAST MAY BE
THE CLOUD COVER TONIGHT AND SAT MORNING AND RESULTANT MINS/MAXES.
THE NAM IS PRETTY AGGRESSIVE IN ADVECTING LOW CRUD/STRATUS IN FROM
THE EAST/SOUTHEAST TONIGHT AND PILING IT UP IN THE MOUNTAINS.
HOWEVER...THE GFS IS NOT SO BULLISH ON THE LOW LEVEL MOISTURE. IT
STILL MAKES LOWER CLOUDS /BELOW 8H/ BUT IS MORE NORTHEASTERLY WITH
THE WINDS ON THE SRN PERIPHERY OF THE HIGH. THUS...MORE DRY AIR IS
SEEN ADVECTING INTO THE AREA IN THE GFS SOLUTION. THIS ALLOWS THE
MARITIME AIR/CLOUDS TO DRY OUT QUICKLY WITH MINIMAL MIXING. THE
TROUBLE WITH THE DRIER SOLUTION IS THAT WE HAVE BEEN PRETTY MUGGY
AND THE MDL OMEGA FIELDS DO NOT PORTRAY SOME OVERWHELMING DOWN-
MOTION. IN FACT...THEY ARE PRETTY NEUTRAL. VERY ISOLATED DIURNAL
CONVECTION IS POSSIBLE IN THE FAR WEST/SOUTHWEST ON SAT...BUT THE
PWATS WILL BE MUCH LOWER - ONLY RANGING FROM 1 INCH IN THE NE TO
1.25 IN THE WEST. AT THIS POINT...THE MOST PROBABLE SOLUTION IN
OUR WEAK FLOW IS THAT THE SFC HIGH STAYS UP OVER NEW ENGLAND AND
THE DRY AIR MAKES ONLY SLOW PROGRESS TO MOVE ACROSS THE REGION.
WILL KEEP IT MORE CLOUDY AND COOLER IN THE FIRST PART OF THE DAY
AND KEEP MAXES SHORT OF GFS-MOS GUIDANCE.

&&

.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 AMPLYIFYING 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 /22Z FRIDAY THROUGH WEDNESDAY/...
GENERALLY VFR CONDS EXPECTED THROUGH EARLY EVENING HOURS...SAVE
WHERE ISOLATED SHRA/TSRA MAY IMPACT AIRFIELDS...MAINLY ACROSS
SOUTHERN PA. A BRIEF VIS REDUCTION IS POSSIBLE IN A FEW SPOTS FROM
THESE STORMS...MAINLY THRU 05/01Z.

A MOIST SERLY FLOW BEHIND THE COLD FRONT WILL LIKELY PRODUCE SOME
LOW CIGS ACROSS THE MTNS OF CENTRAL PA TONIGHT AND EARLY SAT AM. 

SFC HIGH PRESSURE WILL BUILD INTO THE REGION FOR THE WEEKEND.

OUTLOOK...

SAT...AM LOW CIGS POSS...MAINLY KBFD/KJST. 

SUN-TUE...PATCHY AM FOG POSS...MAINLY KBFD/KIPT.

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

&&

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

&&

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



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