Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 301848
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
248 PM EDT SAT APR 30 2016

.SYNOPSIS...
A LARGE LOW PRESSURE AREA OVER THE CENTRAL U.S. WILL SLIDE TO THE
EAST OVER THE NEXT FEW DAYS. EXPECT A PROLONGED PERIOD OF RAIN
THROUGH AT LEAST MONDAY MORNING WHEN THE LOW MOVES TO THE EAST OF
THE STATE. UNSETTLED WEATHER WILL CONTINUE NEXT WEEK WITH SEVERAL
CHANCES FOR RAIN.

&&

.NEAR TERM /THROUGH TONIGHT/...
VERY MUCH WARMER AIR WILL BE MOVING IN FROM THE WEST. THIS WILL
BRING A BIG INCREASE IN MOISTURE AS WELL. BECAUSE OF THE
PERSISTENT CLOUD COVER AND EASTERLY FLOW...THE TEMPS MAY NOT MOVE
MUCH AT ALL THROUGH THE NIGHT...AND IT MAY EVEN NUDGE UP JUST A
DEGREE IN THE WEST BY SUNRISE. THE TIMING OF THE RAIN ONSET SEEMS
TO BE RATHER SIMILAR TO LAST MODEL CYCLE. THE WEST SHOULD GET WET
AROUND OR JUST BEFORE SUNSET...BUT IT MIGHT TAKE UNTIL AFTER
MIDNIGHT FOR THE RAIN TO WORK DOWN INTO THE EASTERN VALLEYS.
HIGHEST PWATS WILL NOT BE UNTIL LATER TONIGHT...WHEN THEY PEAK IN
THE 1.25-1.5 INCH RANGE. LLJET NEVER GETS ALL THAT FAST AND IS
MORE OUT OF THE SW THAN E/SE WHERE THE DEEP AND CLOSE MOISTURE
SOURCE IS. THIS FIRST WAVE OF LIFT LAST ALL NIGHT. THE VISBY MAY
GET LOW IN THE SW/MTNS WHERE THE INVERSION GETS STEEP AND CLOUDS
HUG THE HILL TOPS. KEPT MENTIONS OF FOG AND EXPANDED THEM A BIT AS
WELL.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
THE WAVE GENERATING THE RAIN WILL BE GETTING TO THE EAST OF OUR
LATITUDE IN THE MORNING...BUT RAIN WILL CONTINUE FOR AT LEAST THE
MORNING IN THE EASTERN HALF OF THE AREA. THE WARMER AIR WILL TRY
TO WORK DOWN TO THE SFC DURING THE DAY/AFTN BUT RESIDUAL MOISTURE
MAY KEEP LOTS OF LOW CLOUDS IN PLACE. RAINFALL BY NOON WILL BE
INTO THE 0.5 TO 1 INCH RANGE. THE LOW WILL MOVE INTO OH AND NW PA
ON SUNDAY...OCCLUDING IT/S COLD AND WARM FRONTS AS IT DOES SO. A
SECOND WAVE OF DECENT LIFT WILL COINCIDE WITH THE TRIPLE POINT
INCHING INTO CENTRAL PA SUNDAY EVENING. WE WILL LIKELY BE IN AN
AREA OF NVA AND DRYING ALOFT. SO FOR A WHILE IN THE DAYTIME ON
SUNDAY...WE SHOULD BE IN A LULL. HOWEVER...IF SOME BREAKS CAN
DEVELOP AND SOME MEAGER FORCING PASS OVERHEAD...WE MAY BE ABLE TO
POP A FEW TALL SHRA/SHORT TSRA. BUT THE HEIGHTS WILL NOT HAVE
FALLEN MUCH BY THAT TIME...AND THE CLOUD COVER MAY BE STICKING
TIGHT. THE WARM SECTOR DOES GET RATHER CLOSE...THOUGH. THE WARM
FRONT WILL BE BARELY INTO OR WILL BE HALTING AT THE
LAURELS/ALLEGHENIES. THUS...LLVL SHEAR COULD BE MAXIMIZED THERE. A FEW
ROTATING STORMS ARE POSSIBLE WITH LOWERED BUT PROBABLY ELEVATED
INSTABILITY IN THAT S/W REGION. DUE TO THE PRESENCE OF ELEVATED
INSTABILITY AND POSSIBILITY OF MIXING ACROSS THE REST OF THE
AREA...WILL KEEP CHC/SCT TS IN THE FCST FOR THE AFTN/EVENING.

MAXES WILL BE VERY MUCH DEPENDENT UPON THE AMOUNT OF SUNSHINE
WHICH CAN BREAK THROUGH. A WARM START TO THE DAY WILL HELP US BUT
THE PERSISTENT CLOUDS - ESP IN THE E - WILL LIMIT THE RISE. WILL
GO WITH MAXES ONLY 5-6F HIGHER THAN MORNING TEMPS IN THE
EAST...BUT MORE LIKE 10 OR 12F RISE IN THE WEST. THE WARM AIR MAY
PUSH INTO THE AREA A BIT MORE OVERNIGHT...SO TEMPS SHOULD NOT FALL
PAST THE U40S AND M50S.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
48-HOUR FORECAST RAINFALL TOTALS ENDING 00Z TUESDAY ARE 0.75
NORTH TO 1.25 INCHES SOUTH...WITH HIGHER AMOUNTS OVER THE WESTERN
ALLEGHENIES AND SOUTHERN TIER COUNTIES WHERE MARGINAL INSTABILITY
MAY ALLOW FOR CONVECTIVE ENHANCEMENT. THE FCST RAINFALL SHOULD
HELP THE AREA RECOVER FROM /60-90+ DAY/ DEFICITS GENERALLY ON THE
ORDER OF -2.00 TO -4.00 INCHES. THE LATEST DROUGHT MONITOR NOW HAS
OVER HALF OF PENNSYLVANIA IN ABNORMALLY DRY /D0/ CONDITIONS WITH A
SMALL AREA OF MODERATE DROUGHT /D1/ CONDITIONS FOCUSED OVER
BEDFORD COUNTY.

A PERIOD OF IMPROVING/DRY WEATHER IS LIKELY FROM MONDAY AFTERNOON
THROUGH TUESDAY BEFORE THE PATTERN TURNS UNSETTLED INTO THE
MIDDLE AND SECOND HALF OF NEXT WEEK. THE GLOBAL ENSEMBLE MEANS ALL
SHOW AN AMPLIFIED/ANOMALOUS MEAN UPPER TROUGH DEVELOPING OVER THE
ERN CONUS BUT THERE ARE STILL MULTIPLE SHORTWAVE PIECES OF THE
FCST PUZZLE TO RESOLVE. THE GUIDANCE AGREES IN PRINCIPLE THAT AN
ELONGATED AREA OF SFC LOW PRESSURE WILL BE NEAR OR ALONG THE EAST
COAST/WRN ATLANTIC. HOWEVER QUESTION MARKS WITH THE DETAILS ALOFT
LEADS TO LOW CONFIDENCE/PREDICTABILITY IN THE RAINFALL TIMING AND
COVERAGE PATTERN. BELOW NORMAL HEIGHTS AND DEEPENING UPPER TROUGH
SHOULD FAVOR RELATIVELY COOL TEMPERATURES VS. SEASONAL
CLIMATOLOGY.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
IFR AT JST WILL LIKELY BE SHORT-LIVED AS THE DEWPOINT HAS RISEN
SOME. ELSEWHERE...THE MVFR CIGS IN THE CENTRAL TERMINALS AND VFR
IN THE SE WILL CONTINUE FAIRLY STEADY STATE WITH THE PERSISTENT
FLOW FROM THE E/SE. LOW PRESSURE APPROACHING THE OHIO VALLEY
TONIGHT WILL SPREAD A LARGE SHIELD OF RAIN INTO THE REGION
STARTING IN THE EVENING IN THE SW AND SPREADING TO COVER THE AREA
BY MIDNIGHT. EXPECT THE WORST PERIOD OF CIGS/VIS IN THE LATE NIGHT
UNTIL A FEW HOURS AFTER SUNRISE ON SUNDAY. WARM FRONT EXTENDING IN
FROM THE MAIN LOW WILL TRY TO LIFT INTO THE CENTRAL MTNS...BUT
WILL LIKELY STALL OVER SWRN/WRN PA. HOWEVER...SOME CLEARING IN THE
DAYTIME COULD PRODUCE SCT SHRA/TSRA ACROSS ALL OF THE AREA. THE
MAIN THREAT AREA FOR TSRA IS VCTY JST/AOO. A SECOND WIDE AREA OF
RAIN/LOW CIGS/VIS WILL PUSH ACROSS AS THE MAIN SFC LOW PUSHES
THROUGH SUN NIGHT/EARLY MONDAY MORNING. DRIER AIR WILL WORK IN FOR
A VERY BRIEF TIME ON MONDAY. A WAVE RIDING THROUGH THE DEEP SOUTH
AND MID-ATLANTIC STATES ON TUESDAY WILL PROBABLY SPREAD MORE RAIN
INTO THE SE HALF OF THE AREA MON NIGHT/TUES.

OUTLOOK...

MON PM-TUE...RA POSS SE.

TUE PM...NO SIG WX.

WED...SHRA POSS.

THU...IFR POSS IN RA/FG.

&&

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

&&

$$
SYNOPSIS...LAMBERT
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...LAMBERT/STEINBUGL
AVIATION...DANGELO


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