Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 020321
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1121 PM EDT FRI AUG 1 2014

.SYNOPSIS...
A PERSISTENT MID-LEVEL TROUGH TO OUR WEST AND A STRONG RIDGE OVER
THE WESTERN ATLANTIC WILL ALLOW MOISTURE TO MOVE UP THE EAST
COAST. UNTIL THE TROUGH SURGES TO THE EAST AND PUSHES THE MOISTURE
OFF TO THE EAST...OUR REGION WILL BE ON THE WESTERN EDGE OF THE
MOISTURE PLUME. THE GENERAL TREND OVER THE NEXT SEVERAL DAYS IS
FOR THE MOISTURE PLUME TO SLOWLY SLIDE EAST. CHANCES OF ORGANIZED
RAIN WILL BE GREATER IN THE EAST AND SHOULD SLOWLY DECREASE SUNDAY
INTO TUESDAY.

&&

.NEAR TERM /UNTIL 8 AM SATURDAY MORNING/...
10PM UPDATE...
LITTLE CHANGES MADE...JUST A MINOR TWEAK DOWNWARD TO POPS IN THE
CENTRAL COUNTIES OVERNIGHT...AS CONVECTION IN THE NORTH IS SLIDING
TO THE NORTH. SERN SHOWERS ALMOST NIL AT THIS POINT. BUT THE MAIN
SLUG OF MOISTURE WITH SHARPENING SFC TROUGH HAS YET TO MOVE INTO
THE SERN THIRD OF THE STATE. THIS IS STILL ANTICIPATED TO HAPPEN
LATER TONIGHT AND LAST THROUGH MUCH OF THE MORNING THERE. NWRN
LIMIT OF THE RAIN IS SUSPECT AT THIS POINT...BUT MOST GUIDANCE
KEEPS IT TO THE EAST OF AOO AND UNV. TEMPS ALMOST DOWN TO
DEWPOINTS...SO SOME FOG IS LIKELY IN THE PLACES IT RAINED EARLIER.
TEMPS LOOK GREAT/ON-TRACK.

PREVIOUS...
EARLIER CONVECTION IN THE EAST IS GONE...BUT ADDITIONAL SHRA/TSRA
FORMING NOW UP OVER THE NWRN MTS IN A LINE FROM BRADFORD TO
TIDIOUTE. THIS IS RIGHT WHERE THE NAM FROM 18Z MADE CONVECTION
THIS EVENING. SO...IT HAS MY CONFIDENCE THERE. THE NAM DOES NOT
QUITE HAVE ANY CONVECTION OR STRATIFORM RAIN MOVING INTO THE
OPPOSITE CORNER OF THE CWA NEAR LANCASTER/YORK COS AT THIS TIME.
IT DOES BUBBLE CONVECTION UP FROM THE SE AGAIN LATER
TONIGHT...LIKE THE NARRE AS WAS NOTED BY THE PREV SHIFT.

THE CURRENT RAP SLIDES THE PRECIP IN THE NW TO THE SOUTH - OR VERY
MUCH OPPOSITE THE FLOW AND THE NAM PREDICTION. IT COULD BE THAT
CONVECTION DIES IN PLACE AND ADDITIONAL TOWERS POP UP TO THE
SOUTH. BUT I AM SUSPICIOUS THAT WILL BE THE CASE. SO WILL ADJUST
THE FORECAST TO MATCH THE CURRENT TRENDS AND WEIGHT TOWARD THE NAM
SOLUTION FOR THE NEAR TERM. POPS ARE SET TO INCREASE FROM SE TO NW
OVER THE SE TONIGHT AND WILL KEEP IT THERE AS IT SEEMS TO MATCH
THE CURRENT FLOW AND CONCEPTUAL MODEL. TEMPS AND OTHER PARAMETERS
ON TRACK.

&&

.SHORT TERM /8 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
THE FLOW BETWEEN THE 500 HPA TROUGH TO OUR WEST AND THE 500 HPA
RIDGE TO OUR EAST WILL ALLOW MOISTURE PLUME TO SURGE INTO THE MID-
ATLANTIC REGION SATURDAY.

NAM-GFS-SREF SUGGEST HIGHER POPS IN EAST SATURDAY AM. LOWER POPS
TO WEST THOUGH IMPLIED QPF SHIELDS SHOW A SQUEEZE PLAY WITH A ZONE
OF VERY LOW POPS EXTENDING FROM NY INTO PA. BUT THIS DRY ZONE/S
POSITION VARIES FROM MODEL TO MODEL. THE NAM IS MUCH DRIER IN SW
MOUNTAINS THAN GFS.

DUE TO DEEP MOISTURE BOUNDARY KEPT POPS RELATIVELY HIGH IN
EAST/SOUTHEAST AND SW MOUNTAINS AND LOWER TO NORTH AND WEST. THE
4KM NAM IMPLIES PRETTY QUIET OVER THE REGION AROUND 8 AM AND
NOTHING OF NOTE CONVECTIVELY UNTIL AFTERNOON. THEN IT SHOWS
LITTLE ORGANIZATION AND MOSTLY SCATTERED SHOWERS...WITH THE
HIGHEST CONCENTRATION IN THE WEST-CENTRAL PART OF THE CWA.

MESSAGE...LOTS OF UNCERTAINTY SATURDAY BUT A RELATIVELY DRY
MORNING AFTER 7-8AM IN THE EAST THEN SCATTERED SHOWERS/TSTMS POP
UP AGAIN IN THE AFTERNOON.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
THE FORECAST AREA WILL BE NEAR THE NWRN EDGE OF THE EXTENSIVE
DEEP MOISTURE PLUME STREAMING NNE FROM THE ERN GOMEX AND WRN
ATLANTIC THIS WEEKEND. THE SHORT WAVE TROUGH TO OUR WEST...AND
PERIODS OF WEAK-MDT LARGE SCALE UVVEL ASSOCIATED WITH COMPACT
WAVES AT THE SFC AND ALOFT RIDING NEWD...WILL SPARK ISOLATED TO
SCATTERED NOCTURAL SHOWERS...AND A CHANCE OF A FEW AFTERNOON TSRA
BOTH SUNDAY AND MONDAY.

THE MID AND UPPER FLOW VEERS AROUND TO THE WEST TUESDAY AHEAD OF
SIGNIFICANT UPPER WAVE /AND POTENT SFC CFRONT/ DROPPING SE ACROSS
THE GLAKES. A SECONDARY CFRONT WILL MOVE SE THROUGH THE AREA
DURING THE DAY WEDNESDAY. PWATS WILL BE DROPPING BACK TO NEAR OR
SLIGHTLY BELOW NORMAL /EVEN AHEAD OF THE 2 CFRONTS/.
HOWEVER...850-500 MB LAPSE RATES AHEAD OF BOTH FEATURES WILL BE AS
MUCH AS 6.5C/KM...WHICH WILL LEAD TO SCATTERED...MAINLY AFTERNOON
AND EARLY EVENING TSRA. A FEW OF THE TSRA EACH AFTERNOON COULD BE
ON THE STRONG SIDE. 0-3KM BULK SHEAR WILL BE AOB 15 KTS...SO THE
CFROPAS BOTH DAYS DON/T APPEAR TO POSE A SIGNIFICANT...CONVECTIVE
WIND THREAT ATTM.

FOR LATER NEXT WEEK...A LARGE AREA OF HIGH PRESSURE AT THE SFC
/BENEATH BROAD WESTERLY CONFLUENT FLOW ALOFT/ WILL BUILD IN FROM
THE MIDWEST AND SHOULD BRING AT LEAST A FEW DAY PERIOD OF PARTLY
TO MOSTLY SUNNY WEATHER AND LOW HUMIDITY.

A BLEND OF GEFS...GFS...AND EC GUIDANCE INDICATES SLIGHTLY RISING
HEIGHTS AND A WEAK SHORT WAVE OR TWO EMBEDDED IN THE WESTERLY FLOW
ALOFT. THIS WILL BRING AN INCREASE IN PWATS LATE FRIDAY NIGHT AND
SATURDAY WITH SCATTERED SHRA/TSRA DEVELOPING AS WE HEAD INTO NEXT
WEEKEND.

AFTER A NEAR PERFECT MATCH OF MONTHLY AVG HIGH AND LOW TEMPS TO
NORMAL AT KMDT AND KIPT IN JULY...MAX AND MIN TEMPS IN THE LONG
TERM PERIOD DON/T APPEAR TO STRAY SIGNIFICANTLY FROM NORMAL.
THE WARMEST TEMPS APPEAR TO BE TUESDAY AHEAD OF THE INITIAL CFRONT
AS A DECENT WESTERLY DOWNSLOPE LLVL COMPONENT KICKS IN.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
MVFR CONDITIONS SLOWLY DEVELOPING ACROSS THE REGION...WITH MVFR
VSBYS NOW AT KBFD AND KLNS. SHOWER ACTIVITY NOW CONFINED TO AN
ISOLATED SHOWER IN THE FAR NORTHWEST. HOWEVER...BROADER AREA OF
SHOWERS NOW CREEPING UP FROM VA/MD...AND SHOULD MOVE INTO KLNS AND
KMDT AREAS AFTER 06Z.

OVERALL...LOOK FOR FOG AND HAZE DEVELOPMENT TO CONTINUE
OVERNIGHT...WITH WIDESPREAD MVFR...AND AREAS OF IFR/LIFR. SHOWERS
WILL ALSO LOWER CIGS IN THE EAST.

MODELS CONTINUE TO INDICATE AN AREA OF SHOWERS/LIGHT RAIN WILL
PERSIST INTO EARLY MORNING IN THE SOUTHEAST...THEN EXIT THE REGION
BETWEEN 12Z AND 14Z. IN THE WAKE OF THIS ACTIVITY...PLENTY OF
CLOUDS CAN BE EXPECTED IN THE EAST SATURDAY. DIURNAL HEATING WILL
ALSO TRIGGER MORE CONVECTION DURING THE AFTERNOON...LASTING INTO
SATURDAY EVENING.

OUTLOOK...
SAT-SUN...AM MVFR/IFR...THEN MAINLY VFR BUT WITH SCATTERED
AFTERNOON SHRA/TSRA IMPACTS POSSIBLE.
MON...POSSIBLE AM FOG AREAS MVFR/IFR. OTHERWISE MAINLY VFR.
TUE...SCATTERED SHRA/TSRA WITH APPROACHING COLD FRONT.
WED...SCATTERED SHRA/TSRA.

&&

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

&&

$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...ROSS/LAMBERT
AVIATION...JUNG


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