-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 221011
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
611 AM EDT TUE JUL 22 2014

.SYNOPSIS...
A RIDGE OF HIGH PRESSURE WILL REMAIN OVER PENNSYLVANIA TODAY. A
POTENT COLD FRONT WILL MOVE SOUTHEAST FROM THE GREAT LAKES AND
CROSS THE COMMONWEALTH LATE WEDNESDAY AND WEDNESDAY NIGHT. A
REFRESHINGLY COOLER AND LESS HUMID AIRMASS WILL OVERSPREAD THE
COMMONWEALTH FOR THE END OF THE WEEK INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
1022 MB SFC HIGH PRES CENTERED NEAR KPHL /WITH A RIDGE EXTENDING
TO ITS NW/ WAS PROVIDING TRANQUIL CONDITIONS ACROSS THE CWA EARLY
THIS MORNING. TEMPS...MAINLY IN THE MID TO UPPER 60S...WERE A FEW
DEG F ABOVE NORMAL FOR AN EARLY MORNING LOW.

A DISTINCT...AND NEARLY NORTH/SOUTH AXIS OF HIGH THETA-E AIR
WITHIN THE 925-850 MB LAYER /AND PWATS AROUND 1.5 INCHES/ CREATED
A RATHER EXTENSIVE LAYER OF STRATUS/STRATOCU ACROSS THE CENTRAL
AND EASTERN ZONES. EXPECT THESE CLOUDS TO PERSIST IN A BKN-OVC
LAYER THROUGH 13 OR 14Z.

AFTER THE EARLY TO MID MORNING LOW CLOUDS AND PATCHY FOG MIXES
OUT...TODAY WILL FEATURE NOTICEABLY WARMER TEMPERATURES AS AN
UPPER RIDGE SLIDES EAST FROM THE GRT LKS.

HIGHS MONDAY WERE IN THE M/U80S UPSTREAM OVR MICHIGAN AND EXPECT
SIMILAR READINGS THROUGHOUT THE VALLEYS OF CENTRAL PA THIS
AFTERNOON. THE HIGHER TERRAIN OF THE ALLEGHENY PLATEAU WILL
LIKELY ONLY REACH THE L80S.

DIURNAL HEATING SHOULD RESULT IN MODERATELY HIGH CAPES THIS
AFTN...HELPING TO DEVELOP JUST A FEW PULSE-TYPE SHRA/TSRA DURING
THE MID TO LATE AFTN. THE BEST CHC FOR THE ISOLATED CONVECTION
SHOULD BE ACROSS SOUTHERN PA AND PERHAPS THE LOWER SUSQ
VALLEY...WHILE SURGING MID LVL TEMPS /EXCEEDING 9C AT 700 MB/ OVR
NW PA MAY COMPLETELY SUPPRESS CONVECTION UP THERE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
SIMILAR /AND PERHAPS EVEN MUGGIER/ CONDITIONS ARE EXPECTED FOR
TONIGHT WITH A LIGHT SOUTHERLY FLOW AND 1.5 INCH PWAT AIR KEEPING
TEMPS ABOUT 6-8F ABOVE NORMAL.

VERY WARM MID LEVEL TEMPS /AVERAGING 9C AT 700 MB OVER CENTRAL
PENN/ WILL KEEP CONDITIONS DRY TONIGHT THROUGH MUCH OF WEDNESDAY
MORNING. THE ARRIVAL OF A STRONG COLD FRONT AND UPPER LEVEL
DISTURBANCE WEDNESDAY AFTERNOON AND EVENING WILL CREATE SEVERAL
BANDS OF DEEP UVVEL...HELPING TO BREAK THIS CAP AND FIRE OFF ONE
OR MORE BKN LINES OF STRONG TO POTENTIALLY SVR TSRA.

SPC HAS THE ENTIRE CWA IN THEIR DAY 2 /SEE TEXT/ OUTLOOK. GIVEN
THE PROJECTED HIGH CAPE AND WEAK-MDT DEEP LAYER SHEAR TYPE OF
ENVIRONMENT THE PRIMARY STORM TYPE WILL BE PULSE AND MULTI-CELL
CLUSTERS CAPABLE OF PRODUCING LOCALIZED SVR HAIL AND WET
MICROBURSTS /WITH A FEW MIN-BOW ECHOES POSSIBLE AS WELL/ WEDNESDAY
AFTERNOON THROUGH EARLY WED EVENING.

THANKS TO A WARMING/LLVL...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 MONDAY/...
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. TODAYS 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. A WARM FRONT WILL BE ON THE DOORSTEP OF PA SUNDAY
MORNING...A BIT SLOWER THAN FORECAST YESTERDAY. HAVE THUS ADJUSTED
POPS/TIME TO SUIT. ASSOCIATED COLD FRONT DOES NOT CROSS THE
STATE TIL MONDAY AT THIS POINT...LEADING TO A POTENTIAL PROLONGED
PERIOD OF SHOWERS AND THUNDERSTORMS. AT THIS TIME FRAME
HOWEVER...A LOT WILL LIKELY CHANGE BEFORE WE REACH NEXT WEEKEND.

&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
22/09Z UPDATE...FOG AND STRATUS HAVE EXPANDED AS EXPECTED EVEN
LOWERING FLGT CATS TO VLIFT AT BFD...IFR AT AOO AND LIFR FOR A
TIME AT IPT. OTHERWISE PREVIOUS FCST STILL GENERALLY ON TRACK WITH
GRADUAL IMPROVEMENT EXPECTED THRU MID-LATE MORNING.

22/06Z...NOCTURNAL COOLING OF RATHER MOIST BLYR /SFC DEWPTS IN
THE LOW- MID 60S/ COMBINED WITH NEARLY CALM WINDS WILL ALLOW FOR
EXPANSION OF LOW CIGS AND REDUCED VISBYS IN FOG/BR EARLY THIS
MORNING ACRS CNTRL PA AIRSPACE. WHILE A PERIOD OF IFR CONDS CANNOT
BE RULED OUT PRIOR TO DAYBREAK...KEPT ALL TERMINALS AOA MVFR USING
A BLEND OF PERSISTENCE AND CURRENT TRENDS WITH GUIDANCE AND LAST
NGTS OBS. EXPECT VISBYS TO IMPROVE FASTER THAN CIGS THIS MORNING
WITH VFR LKLY BY 17-18Z.

WARMING TEMPS ALOFT AND VIRTUALLY NO SYNOPTIC FORCING SUGGESTS
VERY LOW PCPN PROBS FOR THE AFTN/EVE. HOWEVER..THERE WILL LKLY BE
ENOUGH INSTABILITY AND MOISTURE TO PRODUCE AN ISOLD TSTM OR TWO
WITH THE HIGHER TERRAIN PERHAPS ACTING AS TRIGGER. NO MENTION OF
PCPN IN TAFS AS POINT PROBS/CVRG WILL BE VERY LOW/SPARSE. DIURNAL
CU SHOULD FACE AFTER DARK WITH SOME PATCHY FOG DEVELOPING OVRNGT.

OUTLOOK...

WED...SCT TSTM IMPACTS LKLY ASSOCD WITH COLD FRONT.
THU...SCT TSTM IMPACTS PSBL SERN AIRFIELDS AS COLD FRONT SLOWS AS
IT APPROACHES THE MID-ATLC COAST.
FRI-SAT...PATCHY A.M. FOG PSBL. OTHRWISE NO SIG WX.

&&

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

&&

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