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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 181101
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
701 AM EDT TUE JUN 18 2013

.SYNOPSIS...
THE PERSISTENT JUNE PATTERN OF BROAD TROUGHING OVER THE MID-
ATLANTIC AND NORTHEAST STATES IS FORECAST TO TRANSITION AND BE
REPLACED BY A SUMMERTIME UPPER LEVEL RIDGE MIGRATING EASTWARD
FROM THE PLAINS. A SLIGHTLY COOLER AND LESS HUMID AIRMASS WILL
FOLLOW IN THE WAKE OF A COLD FRONT TONIGHT INTO THURSDAY.
INCREASING HEAT AND HUMIDITY WILL ARRIVE ON SCHEDULE WITH THE
OFFICIAL START OF ASTRONOMICAL SUMMER...AND LAST INTO THE
UPCOMING WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
BELT OF STRONGER MID-LVL FLOW ON THE SRN EDGE OF SHORTWAVE TROUGH
MOVG EWD FROM QUEBEC TO THE MARITIMES WILL SHIFT EWD ACRS NEW
ENGLAND THIS MORNING. AN ATTENDANT SFC COLD FRONT DRAPED ALONG THE
LWR LKS IS TEAMING WITH A WELL-DEFINED 300MB JET ENTRANCE REGION
TO MAINTAIN A CLUSTER SHOWERS/TSTMS OVER NW PA...WITH A FEW LONE
CELLS CROSSING LK ERIE. THE LATEST MESO MODELS CONTINUE TO WEAKEN
THIS AREA OF PCPN AS IT SHIFTS EWD ACRS MCKEAN CO THRU 12Z. OUTSIDE
OF THE NW MTNS...MOST AREAS SHOULD REMAIN DRY THRU DAYBREAK.

IR SATL LOOP SHOWS A SHIELD OF LYRD MID-HIGH CLOUDS SPREADING NEWD
ACRS CNTRL PA. THESE CLOUDS ARE ASSOCD WITH A SHORTWAVE LIFTING
THRU THE TN VLY AND WEAK SFC LOW ADVANCING EWD TOWARD THE CNTRL
MID-ATLC COAST. ANOTHER COMPACT SHORTWAVE IS CURRENTLY ROTATING
ACRS MN..AND WILL TRACK SEWD INTO THE LWR-MID OH VLY BY THIS
AFTN. THE APPROACHING SHORTWAVE ENERGY /FROM THE SW/ AND
AFOREMENTIONED SFC COLD FRONT /FROM THE NW/ SHOULD PROVIDE
SUFFICIENT FORCING/LIFT TO FUEL SCT TO NMRS TSTM DEVELOPMENT INTO
THE AFTN. HOWEVER THERE IS SOME QUESTION AS TO WHERE THE BEST
LOCATION/AERIAL CVRG WILL BE. THE LATEST HRRR AND 00Z SPC WRF/SSEO
HIGHLIGHT THE AREA SOUTH OF I-80...WITH THE HRRR SHOWING A NOTABLE
INCREASE IN CONVECTION AROUND THE 17-18Z TIMEFRAME.

THE SVR THREAT APPEARS MARGINAL DUE TO WEAK/MODEST INSTABILITY.
HOWEVER I CANT RULE OUT A FEW ORGANIZED STORMS GIVEN 35-40 KT OF
EFFECTIVE BULK SHEAR. COULD ALSO SEE SOME LOCALLY HEAVY RAINS
WITH THE MAIN SURGE OF ANOMALOUS PWATS OVER SOUTHEAST PA. THE
LATER ARRIVING MESO GUIDANCE SEEMS TO BE FORMING A CONSENSUS THAT
THE SRN 1/2 OF THE CWA SHOULD SEE THE MOST ACTIVITY COINCIDENT
WITH PEAK HEATING. AS SUCH...EXPECT TSTM CVRG TO WANE/TAPER OFF
WITH THE ONSET OF NIGHTFALL/SWD MVMT OF COLD FRONT.

THE FRONT WILL PUSH SOUTH ACRS THE CWA BY LATER TONIGHT WITH MUCH
DRIER/BELOW NORMAL PWAT AIR ARRIVING FROM THE NORTH. WILL HOLD
ONTO SOME LOW POPS ALONG THE MASON DIXON LINE INTO EARLY WEDNESDAY
MORNING BUT MOST AREAS SHOULD BE DRY AFT 06Z...ESPECIALLY TO THE
NORTH OF THE TURNPIKE.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
HIGH PRES WILL PREVAIL ON WEDNESDAY BRINGING PLENTY OF SUNSHINE.
THE WEATHER SHOULD BE RATHER COMFORTABLE AND PLEASANT WITH
COOLER NLY WINDS AND LOW HUMIDITY...WITH TEMPS GENERALLY IN THE
70S. CLR/CALM CONDS WED NIGHT SHOULD ALLOW OVERNIGHT LOWS TO FALL
INTO THE LOW-MID 40S ACRS THE NRN TIER...AND LOW-MID 50S IN THE
SOUTH. SOME OF THE USUAL COLD SPOTS IN THE NRN MTNS COULD DIP
INTO THE UPPER 30S.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
A DEEP CLOSED LOW MOVG ACRS THE PACIFIC NW AND NRN ROCKIES WILL
ALLOW THE CENTRAL PLAINS UPPER RIDGE TO SLIDE EWD WITH RISING HGTS
EXPECTED DOWNSTREAM OVER THE ERN CONUS. CONSENSUS OF MODEL AND
ENSEMBLE DATA CONTINUES TO BUILD THE RIDGE TO 588+DM THRU THE
WEEKEND WITH THE FIRST TASTE OF SUMMERTIME HEAT/HUMIDITY ARRIVING
ON SCHEDULE.

LLVL S-SWLY RETURN FLOW AROUND SFC HIGH PRES DRIFTING OFF THE EAST
COAST WILL BRING AN INCREASE IN LLVL MSTR THRU THE END OF THE WORK
WEEK...WITH JUST A SLGT CHC FOR AN AFTN POP-UP/AIRMASS TYPE SHOWER
OR TSTM ON FRI.

ABOVE NORMAL 500 HPA HEIGHTS OVERSPREAD THE COMMONWEALTH THIS
WEEKEND. THIS SHOULD TRANSLATE INTO WARMER-THAN-NORMAL TEMPS WITH
THE GFS-BASED MOS GUID MORE BULLISH THAN THE EC MOS ON THE HEAT.
PATTERN ALSO HAS A RING-OF-FIRE LOOK TO IT SO WILL NEED TO WATCH
FOR MCS ACTIVITY/RIDGE ROLLERS.

&&

.AVIATION /11Z TUESDAY THROUGH SATURDAY/...

-- Changed Discussion --
QUASI STATIONARY BOUNDARY IS CURRENTLY MEADERING IN THE NW CORNER
OF THE STATE. WEAK SHOWERS ARE MAKING THERE WAY ACROSS THE
NORTHERN HALF OF THE STATE. ANY SHOWERS ARE NOT REDUCING
CONDITIONS. LOW LEVEL MOISTURE HAS CREPT UP INTO THE SOUTHEASTERN
CORNER OF THE STATE. IFR VSBYS AT LNS SHOULD CONTINUE FOR THE NEXT
FEW HOURS BUT SHOULD LIFT BY 15Z AT THE LATEST. AS THE BOUNDARY
MOVES TO THE SOUTH SCATTERED SHRA/TSRA SHOULD DEVELOP THIS AFTN.
VFR CONDS WILL PREDOMINATE...WITH BRIEF VSBY REDUCTION POSSIBLE
WITH ANY SHRA/TSRA. CURRENT MODELS SHOW ANY PRECIPITATION COULD
LINGER ALONG THE MASON DIXON LINE...AND AT LNS...MDT AND JST
THROUGH 06Z WEDNESDAY. IFR CIGS AND VSBYS WILL AGAIN BE A
POSSIBILITY TONIGHT.

OUTLOOK...
WED...EARLY AM LGT RAIN/LOW CIGS POSSIBLE JST/AOO.
THU...NO SIG WX EXPECTED.
FRI-SAT...ISOLD PM TSRA IMPACTS POSSIBLE.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...STEINBUGL
AVIATION...FITZGERALD/CERU