Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 222007
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
407 PM EDT TUE JUL 22 2014

.SYNOPSIS...
A COLD FRONT WILL MOVE ACROSS THE COMMONWEALTH LATE WEDNESDAY AND
WEDNESDAY NIGHT. A REFRESHING COOLER AND LESS HUMID AIRMASS WILL
OVERSPREAD THE COMMONWEALTH FOR THE END OF THE WEEK INTO THE
WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
CONVECTIVE MIXING HAS LED TO THE DEMISE OF THE LOW CLOUD
SHIELD...BUT NOW WE ARE SEEING MORE CUMULUS FORM. SATELLITE AND
RADAR INDICATE A COUPLE OF SMALL SHOWERS TRYING TO GET GOING IN
THE WARM HUMID AIRMASS...BUT THE WARM DRY AIR ALOFT IS SO FAR
KEEPING ACTIVITY MAINLY CAPPED.

MESO ANAL SHOWS A TONGUE OF MUCAPES EXCEEDING 2000J NOSING INTO
SWRN PA BUT ALSO INDICATES VERY WARM MID LEVEL AIR PUSHING INTO
THE AREA. THIS WILL HELP SUPPRESS ACTIVITY DESPITE THE
EXPECTATIONS OF A FAIR AMOUNT OF AVAILABLE INSTABILITY THIS
AFTERNOON. THE BEST CHC FOR THE ISOLATED CONVECTION WOULD SEEM TO
BE OVER SOUTHERN AREAS EAST TO THE LOWER SUSQ VALLEY WHERE
SLIGHTLY COOLER MID LEVEL TEMPS ARE FORECAST TO PERSIST.

AFTERNOON HIGHS WILL BE NOTICEABLY WARMER THAN PREVIOUS
DAYS...TOPPING OUT NEAR 90 OVER THE SE AND IN THE MID 80S OVER THE
NW.

THE OVERNIGHT WILL BE SIMILAR TO LAST NIGHT...DRY BUT WITH PATCHY
LOW CLOUDS AND FOG FORMING AFTER MIDNIGHT. IT WILL BE A HUMID
NIGHT FOR SLEEPING.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
A DRY START TO THE DAY WEDNESDAY WILL GIVE WAY TO INCREASING
CHANCES FOR SHOWERS AND THUNDERSTORMS AS FORCING INCREASES
ASSOCIATED WITH THE APPROACHING COLD FRONT. WE ARE NOT OUTLOOKED
FOR SEVERE AT THIS TIME BUT THE AIRMASS CHANGE WILL BE FAIRLY
STARK FOR MID JULY AND FORECAST CAPES IN EXCESS OF 1200J SUGGEST
SPC MIGHT EXPAND THEIR SLIGHT RISK WITH LATER UPDATES. EITHER WAY
IT LOOKS LIKE AN UNSETTLED AND WET DAY AS THE FRONT TRAVERSES THE
REGION.

THANKS TO A WARMING LOW LEVEL WSW DOWNSLOPE FLOW AHEAD OF THE
CFRONT...HIGH TEMPS WED WILL BE THE WARMEST OF THE WEEK...RANGING
FROM THE LOWER 80S ACROSS THE HIGHEST TERRAIN OF THE NORTH AND
WEST...TO THE MID AND UPPER 80S IN THE CENTRAL VALLEY...AND LOWER
90S IN THE GREATER YORK/HARRISBURG AREA.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...

OVERALL SCENARIO REMAINS UNCHANGED IN THE LONG TERM PERIOD AS A
LARGE UPPER RIDGE BUILDING OVER THE FOUR CORNERS REGION IS
FORECAST TO EXPAND NORTH AND EAST INTO THE ROCKIES AND PLAINS
DURING THE PERIOD. DOWNSTREAM...THIS WILL LEAD TO LONG WAVE
TROFFING OVER THE EASTERN THIRD OF THE COUNTRY. UPPER LOW TO THE
EAST OF HUDSON BAY WILL BE STRENGTHENED AT TIMES BY SHORTWAVE
ENERGY IN THE STRONGER JET STREAM FLOW ACROSS CANADA. SOUTHWARD
EXTENSION OF THIS LOW/TROF WILL AT TIMES DURING THE PERIOD
STRENGTHENING THE TROFFING ACROSS THE NORTHEASTERN U.S./OUR
REGION. THE TREND OF MEDIUM RANGE MODEL GUIDANCE IS FOR
STRONGER/DEEPER TROFFING DOWNSTREAM ACROSS THE EASTERN
U.S...DEVELOPING AN ALMOST FULL LATITUDE TROF EXTENDING FROM THE
EASTERN CANADA LOW SWD TO FLORIDA. THIS WILL LIKELY SERVE TO
EXPAND AND PROLONG THE CHANCES FOR PCPN THIS WEEKEND.

GUIDANCE FORECASTS CONTINUE TO BRING A FRONT AND INCREASED
CHANGES FOR PRECIPITATION TOWARD PA IN THE WEDNESDAY/THURSDAY TIME
FRAME AND SHOW A SECOND...POTENTIALLY STRONGER SYSTEM LATE NEXT
WEEKEND. THE TREND OF STRONGER TROUGHING MENTIONED ABOVE HAS LEAD
TO SLOWER ARRIVAL AND DEPARTURE OF THE FRONTAL SYSTEM IN THE DAILY
PROGS. THE ECMWF IN LATEST RUN HAS SLOWED UP THE PROGRESSION OF
THIS UPPER LEVEL LOW...WHERE THE GFS OPERATIONAL AND ENSEMBLES
HAVE SPED UP ITS PROGRESSION THROUGH THE GREAT LAKES REGION. A
WARM FRONT WILL BE ON THE DOORSTEP OF PA SUNDAY...AS THE EC
CONTINUES TO SLOW ITS PROGRESSION SO EXPECT THE WARM FRONT TO MOVE
IN CLOSER TO MIDDAY SUNDAY. HAVE THUS ADJUSTED POPS/TIME.

ASSOCIATED COLD FRONT DOES NOT CROSS THE STATE TIL MONDAY...WHERE
SURPRISINGLY AT THIS POINT...THE EC AND GFS COME CLOSELY IN PHASE.
THIS LARGE UPPER LEVEL LOW COULD BECOME QUASI STATIONARY OVER
SOUTHERN CANADA...GREAT LAKES REGION WHICH COULD LEAD TO A
POTENTIAL PROLONGED PERIOD OF SHOWERS AND THUNDERSTORM THROUGH THE
MIDDLE OF NEXT WEEK.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
ALL TERMINALS ARE VFR AT THIS HOUR...AND WILL REMAIN INTO THE
EVENING. WARMING TEMPS ALOFT AND LACK OF STRONG FORCING SUGGESTS
VERY LOW CHANCES OF AFTERNOON POP-UP SHOWERS OR THUNDERSTORMS. NO
MENTION OF THUNDERSTORMS IN TAFS AS POINT PROBS/PCPN CVRG WILL BE
VERY LOW/SPARSE. THE BEST CHANCE OF A SHOWER OR THUNDERSTORM WILL
BE SOUTH OF I-80 INTO THE EVENING.

DIURNAL CU SHOULD FADE AFTER DARK WITH SOME PATCHY FOG AND ASSOCD
LOWER CIGS/VIZ RE-DEVELOPING OVERNIGHT.

WEDNESDAY WILL FEATURE A STRONG COLD FRONT PASSING THROUGH THE
AREA ALONG WITH NUMEROUS SHOWERS AND THUNDERSTORMS. TERMINALS WILL
BE MAINLY VFR BUT WITH IMPACTS INCREASING ALONG WITH THE COVERAGE
OF THE SHOWERS AND STORMS..ESPECIALLY IN THE AFTERNOON AND
EVENING.

OUTLOOK...

THU...SCT TSTM IMPACTS PSBL SERN AIRFIELDS AS COLD FRONT SLOWS
ALONG THE MID-ATLC COAST.

FRI-SAT...PATCHY A.M. FOG. OTHERWISE NO SIG WX.

&&

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

&&

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



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