Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 122015
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
415 PM EDT SAT JUL 12 2014

.SYNOPSIS...
WEAK HIGH PRESSURE WILL DRIFT EAST OFF THE MID ATLANTIC COAST
THIS AFTERNOON...SETTING UP AN INCREASINGLY HUMID AIR FLOW FROM
THE SOUTH. AN UNSETTLED WEATHER PATTERN WILL DEVELOP ACROSS THE
NORTHWEST PART OF THE STATE LATE TONIGHT...BEFORE SPREADING ACROSS
THE ENTIRE REGION SUNDAY AND MONDAY AS A COLD FRONT PUSHES
SOUTHEAST FROM THE GREAT LAKES. COOLER AND DRIER AIR WILL MOVE IN
BEHIND THE COLD FRONT FOR THE MID TO LATE WEEK PERIOD.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
EXPECT MOSTLY SUNNY SKIES TO PREVAIL ACRS CENTRAL AND WESTERN
SECTIONS OF THE CWA THROUGH THE AFTERNOON HOURS AS 3 DEG C OF
WARMING ALOFT /4-5C AT 700 MB...INCREASING TO 7-8C BY LATE THIS
AFTERNOON/ AND A RELATIVE MIN IN PWAT /AROUND 1.0 INCH/ SPREADS
EAST OVER THE AREA...AND EFFECTIVELY CAPS OFF ANY CU PRIOR TO
REACHING THE TCU STAGE.

AN AREA OF ISOLD/SCATTERED SHOWERS AND A FEW LOW- TOPPED PULSE
TSRA HAVE FORMED ACROSS THE SUSQ VALLEY AND NE MTNS...WHERE MID
LEVEL TEMPS HAVE BEEN SLIGHTLY COOLER AND WHERE A NORTH/SOUTH
RIBBON OF HIGHER PWAT AIR /AROUND 1.5 INCHES/ IS COLLOCATED. HAVE
INCREASED THE POPS AND QPF BASED ON THE TIMING OF THE STORMS.
THESE STORMS HAVE STRONG VILS AND HAVE HAD ALMOST 3 INCHES OF
PRECIPITATION IN SOME AREAS IN EASTERN LEBANON COUNTY.

MID TO LATE AFTERNOON TEMPS WILL PEAK IN THE LOWER 80S ACROSS THE
NRN AND WRN MTNS...AND IN THE 85-87F RANGE ACROSS THE MID AND
LOWER SUSQ VALLEY.

A FAIRLY POTENT VORT MAX/SHORT WAVE TROUGH WILL PUSH EAST THROUGH
THE LOWER LAKES LATE TONIGHT. SHRA/TSRA SHOULD APPROACH THE NWRN
COUNTIES AS A 35-40KT SWRLY LLJET DEVELOPS IN OHIO AND SPREADS
INTO NRN PA.

WILL KEEP CONTINUITY WITH POPS INCREASING TONIGHT...WITH THE
ARRIVAL OF SHOWERS/TSRA MAINLY AFTER 07Z SUNDAY. CLOUD COVER
INCREASES OVERNIGHT...SO TEMPS WILL LIKELY NOT DROP TO NEAR
NORMAL. EXPECT FAIRLY UNIFORM LOWS IN THE 60S.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
SFC COLD FRONT WILL BE SLIDING GRADUALLY SE ACROSS THE GLAKES
SUNDAY...REACHING A LINE FROM NEAR CYYZ TO KTOL TO KIND AROUND 00Z
MONDAY.

REMNANT MID AND HIGH CLOUDS ARE EXPECTED FOR THE MORNING/MIDDAY
HOURS SUNDAY...FROM THE POTENTIAL UPSTREAM MCS. SCATTERED
SHRA/ISOLATED TSRA WILL DRIFT QUICKLY EAST /AT 35-40 KTS/ ACROSS
THE NORTHERN MTNS BETWEEN 12-16 SUNDAY.

AFTERWARD...A COMPLEX CLOUD/LLVL HEATING PATTERN WITH SEVERAL
OUTFLOW BOUNDARIES WILL FIRE OFF NEW /AND LOCALLY STRONG TO SVR
TSRA/ AS MEAN SFC BASED CAPES VIA THE SREF RAMP UP TO BETWEEN
1000-1500 J/KG...WITH POCKETS OF LOCALLY HIGHER INSTABILITY NEAR
2500 J/KG /VIA THE 12Z NAM/.

WHAT SIGNIFICANT POCKETS OF HIGHER CAPES CAN DEVELOP...THEY/LL
HAVE THE OPPORTUNITY TO COMBINE WITH MODERATELY STRONG SPEED AND
DIRECTIONAL SHEAR TO CREATE EHI/S OF 1.5-2.5 M2/S2. SPC ALSO NOTES
THAT MODEL HODOGRAPHS FAVOR BOWING LINE SEGMENTS AND EVEN A FEW
SUPERCELLS/BRIEF TORNADOES ACROSS THE CWA. THEIR DAY 2 SLIGHT RISK
AREA FOR SUNDAY COVERS A LITTLE MORE THAN THE SE HALF OF PENN.

THERE SHOULD BE 2-3 PRIMARY AREAS OF CONVECTION...THE FIRST BEING
DEVELOPING ACROSS CENTRAL/NRN PENN INVOF OF OUTFLOW
BOUNDARIES...THE SECOND NEAR THE LEE TROUGH ACROSS THE CENTRAL
MTNS AND SUSQ VALLEY...AND THE THIRD FORMING ACROSS THE WRN
MTNS...ALONG AND AHEAD OF THE APPROACHING CFRONT.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...

THE FOCUS FOR THE BEST CONVERGENCE SHIFTS SLOWLY EAST ACROSS THE
AREA SUNDAY NIGHT AND MONDAY. HEIGHT FALLS OF 10DAM ARE EXPECTED
MONDAY AS A SIGNIFICANT TROUGH PUSHES FORCIBLY INTO THE NRN GREAT
LAKES. SPC HAS MOST OF THE CWA /EXCEPT FOR THE FAR NW ZONES/ IN
THE SLIGHT RISK AREA FOR MONDAY.

THE STORMS BOTH SUNDAY AND MONDAY WILL BE MOVING PRETTY FAST FROM
WEST TO EAST...BUT TRAINING IS POSSIBLE DUE TO THE E-W BAROCLINIC
ZONE.

PWATS INCREASE TO NEAR 2 INCHES ON MONDAY. THUS...SOME HEAVY RAIN
AND PERHAPS LOCALIZED FLOODING ARE POSSIBLE. CURRENTLY...3HR FFG
ACROSS THE REGION IS IN THE 2.5 TO 3.5 INCH RANGE...WHICH WILL
TEMPER THE RISK OF FLASH FLOODING UNLESS SEVERAL TSRA CAN TRAIN
OVER THE SAME LOCATIONS OVER THE SPAN OF JUST A FEW HOURS. SEVERAL
ROUNDS OF SHOWERS/TSRA SHOULD LOWER THESE FFG VALUES BY MONDAY
WHEN THE CFRONT MOVES THROUGH. WILL NOT MENTION FLOODING IN THE
HWO YET...BUT WILL CONTINUE TO MENTION THE POSSIBILITY OF SEVERE
TSRA MICROBURSTS.

 THE GFS AND NAM GUIDANCE IS MUCH QUICKER TO PUSH THE FRONT
THROUGH...WITH THE ECMWF DEEPENING THE UPPER LEVEL TROUGH...THOUGH
THE LATEST RUN HAS OPENED UP THE CLOSED LOW. HOWEVER THE GFS
BRINGS IN THE DRIER AIR THROUGH QUICKER...KEEPING ALL BUT THE ERN
THIRD OF THE AREA DRY ON TUESDAY. THE EC DEVELOPS A COHERENT SFC
LOW OVER THE MID MS VALLEY AND MOVES IT TO OUR W/N ON TUESDAY AS
IT DEEPENS TO NEAR 1003MB. WILL THEREFORE KEEP ON WITH MENTIONS OF
SHRA/TSRA FOR THE ENTIRE SHORT TERM PERIOD.

HIGH AMPLITUDE RIDGE/TROUGH PATTERN DEVELOPS ACROSS THE MUCH OF
NORTH AMERICA BEGINNING LATE IN THE WEEKEND...AND CONTINUES
THROUGH THE FIRST HALF OF NEXT WEEK.

THE BRUNT OF THE GREATEST 850-700 MB TEMP ANOMALIES AND
ASSOCIATED BELOW NORMAL 500 MB HEIGHTS WILL BE AIMED AT THE LOWER
OHIO VALLEY AND MID MISS VALLEY TUESDAY AND WEDNESDAY...WITH OUR
REGION RESIDING ON THE ACTIVE/EASTERN SIDE OF THIS SLOW MOVING
FEATURE.

AS ADDITIONAL ENERGY IS DRIVEN SSE INTO THE BACK SIDE OF THE HIGH
AMPLITUDE MIDWEST TROUGH...PROLONGED HIGH PWAT AIR /AND LIFT
BENEATH THE RIGHT ENTRANCE REGION OF AN UPPER JET/ MAY LINGER
ACROSS THE SERN ZONES WITH SCATTERED...MAINLY AFTERNOON TSRA
WEDNESDAY AFTERNOON.

THE PATTERN OVER THE NRN CONUS AND SRN CANADA APPEARS TO DE-
AMPLIFY LATER NEXT WEEK AS THE EASTERN U.S. TROUGH BEGINS TO SHEAR
OUT TO THE NE.

THE DRIEST PERIOD OF THE LONG TERM WILL BE THURSDAY AND
FRIDAY...THOUGH SOME ISOLATED CONVECTION STILL CANT BE RULED OUT
EITHER OF THOSE TWO DAYS.

TEMPS START OUT AOA NORMAL PRECEDING THE CFROPA NEXT SUNDAY...AND
PERHAPS MONDAY ACROSS THE SE ZONES...THEN COOL TO AT LEAST  4-6F
BELOW NORMAL FOR DAYTIME HIGHS TUESDAY THROUGH THURSDAY. TEMPS
WILL LIKELY REBOUND TO NEAR NORMAL LATE NEXT WEEK.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
MAINLY VFR WILL PREVAIL FOR THE REGION THROUGH EARLY TONIGHT.
WILL INCLUDE VCSH AT KMDT AND KLNS BUT LEAVE OUT THE POTENTIAL FOR
VERY BRIEF MVFR VSBYS AND CIGS FROM THE ACTUAL TAFS.

SOME HIGH END MVFR FG AND HZ MAY FORM FOR A FEW HOURS ONCE AGAIN
LATE TONIGHT/EARLY SUNDAY MORNING THROUGHOUT THE CENTRAL VALLEYS
AND SUSQ REGION TAF SITES. AN APPROACHING WARM FRONT WILL BRING
THE CHANCE OF TSRA IMPACTS TO THE NW MTNS TOWARD DAWN SUNDAY.

OUTLOOK...

SUN...BRIEF...MAINLY PM...THUNDERSTORM IMPACTS POSSIBLE.

MON-MONDAY NIGHT...NUMEROUS SHOWERS/TSRA WITH MAINLY BRIEF PERIODS
OF IFR TO MVFR /MAINLY 18Z MONDAY THROUGH 02Z TUESDAY/.

WED AND THU...NO SIG WX EXPECTED.

&&

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

&&

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



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