Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 300717
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
317 AM EDT TUE JUN 30 2015

.SYNOPSIS...
A WARM FRONT WILL MOVE NORTHEAST ACROSS THE STATE OVERNIGHT
BRINGING SHOWERS TO PRIMARILY THE NORTHWEST HALF OF THE STATE.
WARMER AND MORE UNSTABLE AIR WILL ENCOMPASS THE REGION TUESDAY
HELPING TO TRIGGER NUMEROUS SHOWERS AND SCATTERED AFTERNOON
THUNDERSTORMS AS A TROUGH OF LOW PRESSURE AT THE SURFACE AND ALOFT
APPROACHES FROM THE WEST. EXPECT AN UNSETTLED WEATHER PATTERN TO
PERSIST INTO THE UPCOMING HOLIDAY WEEKEND AS A BROAD BUT WEAKENING
UPPER LEVEL TROUGH REMAINS POSITIONED OVER THE LOWER 48 EAST OF
THE CONTINENTAL DIVIDE.

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
MID LVL SHORTWAVE LIFTING NE THRU THE E GRT LKS EARLY THIS
MORNING. SOUTHERLY LL JET AND ASSOC WAA/ISENTROPIC LIFT IN ADVANCE
OF THIS FEATURE IS PRODUCING PERIODS OF RAIN ACROSS
WESTERN/CENTRAL PA AS OF 06Z. LATEST RADAR TRENDS AND HRRR OUTPUT
SUPPORT RAISING OVERNIGHT POPS TO BTWN 80-90 PCT ACROSS THE
ALLEGHENY PLATEAU...WHILE CHC OF RAIN LOOKS MUCH LOWER ACROSS THE
LOWER SUSQ VALLEY...FURTHER FROM SHORTWAVE AND ASSOC LG SCALE
FORCING.

A FEW LIGHTNING STRIKES NOTED AT NOSE OF LL JET ACROSS SW PA AT
06Z AND MDL SOUNDINGS SHOW SOME MARGINAL ELEVATED INSTABILITY
ACROSS MUCH OF CENTRAL PA EARLY THIS AM...AS LL JET SWEEPS
EASTWARD. THEREFORE...WILL MAINTAIN THE SLIGHT CHC OF THUNDERS
ACROSS THE CENTRAL MTNS AND ALLEGHENY PLATEAU EARLY THIS AM.

TEMPS ON TRACK TO BOTTOM OUT EARLY THIS AM FROM THE U50S ACROSS
THE N MTNS...TO THE M60S ACROSS THE SE COUNTIES.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
THE LEAD SHORTWAVE IS FCST TO WEAKEN AS IT LIFTS THRU THE E GRT
LKS LATER TODAY. LATEST HRRR/NAM SIM REFLECTIVITY INDICATE
A DWINDLING BATCH OF SHOWERS ASSOC WITH THIS FEATURE WILL LIFT
THRU THE NE COUNTIES BTWN 12Z-15Z. AT THE SFC...WARM FRONT WILL BE
PUSHING NE ACROSS THE REGION DURING THE LATE AM AND EARLY
AFTN...BRINGING BRIGHTENING SKIES EARLY IN THE DAY ACROSS THE
ALLEGHENIES...AND BY EARLY AFTN ACROSS THE SUSQ VALLEY.

DIABATIC HEATING RESULTS IN MODERATE MODEL CAPES OF ARND 1000
J/KG BY AFTN ACROSS CENTRAL PA...WITH SOMEWHAT GREATER INSTABILITY
NOTED ACROSS THE SUSQ VALLEY...WHERE TRAILING LL JET/PLUME OF
HIGHER PWATS LIE IN ASSOC WITH WEAKENING SHORTWAVE OVR THE E GRT
LKS. HAVE THUS...PLACED THE HIGHEST /LIKELY/ CHC OF PM TSRA ACROSS
THE EASTERN COUNTIES. MDL 0-6KM SHEAR OF ARND 40KTS SUPPORTS THE
POSSIBILITY OF A FEW SUPERCELLS AND A SLIGHT RISK OF DAMAGING
WGUSTS FROM THE CENTRAL MTNS EASTWARD THIS AFTN. WEAKER MID LVL
WINDS IMPLY LESS CHC OF SVR WX ACROSS THE NW MTNS.

OTHER AREA OF CONCERN WILL BE THE POSSIBILITY OF LOCALIZED FLOODING...DUE
TO WET GROUND AND EXPECTATION OF ISOLD RAINFALL AMTS OF ARND 3
INCHES BASED ON OUTPUT FROM CONVECTION-ALLOWING MDLS. WILL MENTION
IN HWO FOR NOW...BUT A FFA COULD BE CONSIDERED FOR THE SUSQ
VALLEY...WHERE PLUME OF HIGHEST MOISTURE WILL LIE.

PTSUNNY SKIES SHOULD PUSH TEMPS INTO THE M70S OVR THE ALLEGHENIES
THIS AFTN...AND THE L80S ACROSS THE SUSQ VALLEY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THE LARGE UPPER LEVEL LOW OVER NORTHERN CANADA THAT WILL BE
DOMINATING THE WEATHER PATTERN OVER THE NEXT WEEK WILL BRING A
DEEPENING TROUGH THAT WILL CONTINUE TO ADVECT WARM MOIST
SOUTHWESTERLY FLOW INTO THE REGION TUESDAY NIGHT INTO WEDNESDAY.
MID LEVEL PERTURBATIONS AND SHORT WAVE TROUGHS SHOULD ENHANCE
LAPSE RATES. DAY 2 OUTLOOK IS CURRENTLY MARGINAL FOR ALMOST ALL OF
PENNSYLVANIA. SO EXPECT ANY TSTMS THAT FORM TUESDAY AFTERNOON INTO
EVENING TO LINGER TUESDAY NIGHT INTO POSSIBLY WEDNESDAY.

AS THE MAIN TROUGH LIFTS AND EXITS THE REGION WEDNESDAY  THE
CONVECTIVE ENVIRONMENT SHIFTS THE BEST INSTABILITY WITH LARGER
VORTICIES DUE TO A SHORT WAVE THAT SHOULD ALLOW FOR LOW LVL LAPSE
RATES TO BE STRONGER THROUGH ALONG A FRONTAL BOUNDARY.

MODELS CONTINUING TO TREND MORE ZONAL FLOW LATE WEDNESDAY NIGHT
INTO THURSDAY. WITH AN AMPLIFYING TROUGH SWINGING THROUGH THURSDAY
AFTERNOON. THIS TREND SHOULD ALLOW FOR MORE A MORE SUMMERTIME
REGIME THURSDAY INTO THE WEEKEND. IN THE WAKE OF THURSDAY/S TROUGH
THE GFS/GEFS/EC BEGIN TO DIVERGE IN SOLUTIONS. HOWEVER WITH DRIER
AIR ADVECTING IN AND THE CONSENSUS, THOUGH THE TIMING DIFFERS,
THAT A RIDGE SHOULD BUILD OVER PA THROUGH THE FIRST HALF OF THE
WEEKEND. THIS COULD LIMIT ANY CONVECTION TO ALONG THE MASON DIXON
LINE AND ONLY A SLIGHT CHANCE FOR PRECIPITATION CURRENTLY SUNDAY
EVENING.

SO DESPITE A SERIES OF MID- LEVEL DISTURBANCES MOVING DOWNSTREAM
FROM THE UPPER/MID MISSISSIPPI VALLEY THROUGH THE MID ATLC
REGION...500MB HEIGHTS SHOULD BE IN RECOVERY MODE WHICH SHOULD
ALLOW DAYTIME TEMPERATURES TO TREND WARMER INTO THE JULY 4TH
HOLIDAY WEEKEND.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS DOMINATING THE REGION EARLY THIS MORNING. LIGHT
SHOWERS ARE INCREASING IN COVERAGE AND MOVING SW TO NE IN ACROSS
ROUGHLY THE WESTERN TWO THIRDS OF THE STATE AS A WELL- DEFINED
SHORT WAVE TROUGH HELPS TO LIFT A WARM FRONT NORTHWARD. MAY SEE AN
ISOLATED TSTM IN FAR WESTERN COUNTIES...BUT VERY UNLIKELY THROUGH
12Z. LOW LEVEL SW JET OF AROUND 30 KTS SWINGS IN FROM THE SW...AND
WILL BRING MARGINAL LLWS TO KJST-KAOO ALONG WITH MVFR CIGS FOR
MAINLY WESTERN HIGHER TERRAIN. SURFACE WINDS WILL REMAIN LIGHT
AREAWIDE.

MVFR CONDITIONS WILL REMAIN LIKELY FOR WESTERN HIGHER TERRAIN
THROUGH LATE MORNING TUE /WITH BRIEF MVFR CIGS POSS CENTRAL MTNS/.
AN UPPER LEVEL DISTURBANCE OFF TO OUR WEST WILL BRING A COUPLE
ROUNDS OF SHOWERS AND SCT AFTERNOON TSRA.

AN UNSETTLED PATTERN WITH A SERIES OF FRONTS WILL BE AFFECTING
THE REGION MUCH OF THIS WEEK. THE BEST CHANCES OF RESTRICTIONS
WILL BE TUESDAY INTO WEDNESDAY.

OUTLOOK...
TUE...MVFR CIGS LIKELY WEST. OTHERWISE MAINLY VFR. LOCAL
RESTRICTIONS IN SHRA/SCT TSRA. ISO TSTMS MAY BE STRONG IN THE
AFTERNOON.

WED...MVFR CIGS LIKELY WEST. OTHERWISE MAINLY VFR. LOCAL
RESTRICTIONS IN SCT SHRA/TSRA.

THU...MAINLY VFR. ISOLATED TSRA MAINLY SOUTH OF I-80.

FRI...MAINLY VFR. ISOLATED TSRA SOUTH.

SAT...MAINLY VFR. CHANCE SHRA/TSRA.

&&

.CLIMATE...
JUNE 2015 HAS BEEN A WET MONTH ACROSS MUCH OF CENTRAL PA. THROUGH
6/28...OUR TWO LCD CLIMATE SITES /HARRISBURG AND WILLIAMSPORT/ ARE
RANKED 8TH AND 6TH RESPECTIVELY FOR THE WETTEST JUNE ON RECORD.

&&

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

&&

$$
SYNOPSIS...LAMBERT
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD/LAMBERT
LONG TERM...CERU/STEINBUGL
AVIATION...GARTNER/RXR
CLIMATE...



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