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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 221033
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
633 AM EDT WED MAY 22 2013

.SYNOPSIS...
-- Changed Discussion --
LOW PRESSURE OVER THE MIDWEST WILL TRACK NORTHEAST THROUGH THE
LOWER GREAT LAKES REGION TODAY AND UP THE ST. LAWRENCE RIVER
VALLEY ON THURSDAY. A COLD FRONT TRAILING THE LOW WILL CROSS THE
REGION ON THURSDAY...FOLLOWED BY A SECONDARY COLD FRONT ON FRIDAY.
A CANADIAN HIGH PRESSURE SYSTEM WILL USHER IN COOLER AND DRIER
AIR THAT WILL KEEP TEMPERATURES BELOW NORMAL FOR MEMORIAL DAY
WEEKEND.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AREA OF MOD/WEAKENING SHOWERS IS CURRENTLY COVERING MOST OF
WARREN COUNTY AS OF 1015Z. THIS AREA OF PCPN SHOULD LIFT N OF THE
PA/NY BORDER SHORTLY AFT 12Z. SATL LOOP SHOWS CONSIDERABLE MID-
HIGH CLOUDS WITH SOME BREAKS. MESO MDL DATA/HRRR INDICATES ANY
CONVECTION OVER CNTRL PA WILL REMAIN ISOLD THRU 18Z.

ALOFT...SUMMER-LIKE UPPER RIDGE OVER THE SE STATES WILL DRIFT EWD
INTO WRN ATLC TDY. MEANWHILE...SHORTWAVES CURRENTLY ROTATING ACRS
HUDSON BAY AND OVER THE N-CNTRL PLAINS INVOF SIOUX FALLS SOUTH
DAKOTA WILL MERGE AND FORM AN EXPANSIVE 500MB TROUGH FROM SERN
CANADA TO THE CENTRAL GULF COAST BY 12Z THU. AT THE SFC...A LOW IS
FCST TO TRACK ENEWD FM THE UPPER MIDWEST ACRS LWR MI INTO THE ERN
GRT LKS WITH TRAILING COLD FRONT PROGRESSING EWD THRU THE OH VLY.

MEAN SWLY FLOW ON NW SIDE OF DEPARTING UPPER-LEVEL RIDGE WILL
BRING ANOTHER VERY WARM DAY TO CNTRL PA WITH AFTN TEMPS IN THE
80S OR ABOUT +10F ABOVE NORMAL. DEEP LAYER MSTR WILL ALSO REMAIN
HIGH/ABOVE NORMAL WITH PWATS 1-1.5 INCHES. SENSIBLE WX CONCERNS IN
THE NEAR TERM REMAIN FOCUSED ON DIURNAL CONVECTION WITH THE NW 1/2
OF THE CWA IN SLGT RISK. WHILE DESTABILIZATION/INSTABILITY IS NOT
EXPECTED TO BE AS ROBUST AS YESTERDAY OWING TO GREATER MID-HIGH
CLOUD CVRG...LG SCALE FORCING SHOULD BE ON THE UP-TICK AS UPPER-
LEVEL TROUGH AND ASSOCD HT FALLS SHIFT EWD INTO THE UPPER OH VLY
BY 00Z. 700MB TEMPS ARE ALSO PROGGED TO BE ABOUT 2-3F COOLER. THE
LLVL FOCUS WILL REMAIN SOMEWHAT NEBULOUS AS THE MAIN SYNOPTIC COLD
FRONT REMAINS WELL TO THE WEST OF THE AREA. A SUBTLE LEE-TROUGH
MAY PROVIDE AN INITIAL FOCUS FOR MULTI-CELL CLUSTERS ACRS
PORTIONS OF CNTRL AND ERN PA. HOWEVER THE MAIN SVR THREAT WILL BE
ACRS WRN SXNS CLOSER TO THE STRONG FLOW ALOFT. 21Z SREF DATA SHOWS
SWLY LLJ INCREASING TO +2-3SD ACRS WRN PA WHICH COULD AID IN
UPSCALE GROWTH OF ORGANIZED TSTMS OR POSSIBLE MCS OVER OH/LWR
MI/LAKE ERIE - WITH PEAK INTENSITY LKLY BTWN APPROX 21-03Z.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
CONTINUED EWD PROGRESSION OF THE EXPANSIVE ERN CONUS TROUGH IS
EXPECTED THIS PERIOD...HOWEVER IT MAY BE AT SLOWER PACE AS SOME
MODEL DATA IS TRENDING SLOWER/SHARPER BY THE END OF THE PERIOD.
THE ATTENDANT COLD FRONT WILL TRAVERSE THE AREA DURING THE AFTN
AND EVENING BEFORE EXITING THE ERN PART OF THE CWA AROUND MIDNIGHT.

GENERALLY WEAK INSTABILITY IS PROGGED IN THE PRE-FRONTAL WARM
SECTOR. HOWEVER...MODERATE FLOW/0-6KM SHEAR AROUND 40 KTS COULD
ALLOW FOR A FEW STRONG STORMS TO ORGANIZE WHERE POCKETS OF GREATER
HEATING/DESTABILIZATION CAN OCCUR. THIS APPEARS MOST LKLY OVER THE
ERN 1/3 OF THE CWA...WHICH IS HIGHLIGHTED BY THE SPC DAY 2 SEE TEXT
CATEGORICAL OUTLOOK.

A LIGHTER...DEFORMATION PCPN AXIS IS PROGGED TO SET UP OVER THE
AREA THURS NIGHT INTO FRI AS A SHORTWAVE EMBEDDED IN THE LARGER-
SCALE TROUGH DIGS FROM THE GRT LKS TWD WV. THERE ARE SOME NOTABLE
MODEL DIFFS HEADING INTO DAY 3 SURROUNDING THE DEPTH AND SPEED OF
THE H5 TROUGH CROSSING THE MID-ATLC REGION. MORE ON THIS IN THE
LONG TERM SECTION.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
THE 22/00Z NAM/GFS AND NOW ECWMF ARE SLOW AND SHARP WITH THE BASE
OF THE H5 TROUGH CROSSING THE MID-ATLC/NORTHEAST STATES FRI-SUN.
THESE DATA ALSO SHOW A CLOSED MID-LEVEL LOW ROTATING WITHIN THE
LARGER-SCALE TROUGH ACRS NRN VA FRI BEFORE PIVOTING NWD INTO NEW
ENGLAND THIS WEEKEND. WPC IS STILL LEANING AWAY FROM THE CLOSED
SOLUTION HOWEVER THEY HAVE GIVEN A LITTLE MORE WEIGHT TO THE OPRN
GFS/ECMWF TRENDS. THE IMPLICATIONS ARE IMPORTANT ESPECIALLY IN THE
DAY 4 PERIOD WHERE THE GUIDANCE SPREAD IS THE GREATEST/MOST
NOTICEABLE. TO COMBAT THIS...USED A INTERMEDIATE APPROACH TAKING A
BLEND OF THE 00Z ECMWF AND GFS...WITH SLIGHTLY MORE WEIGHTING
TOWARD THE GFS GIVEN WPC PREFERENCE TOWARD THE GEFS MEAN AND AN
OVERALL BETTER FIT TO THE OPRN/ENSEMBLE CONSENSUS.

EXPECT PLENTY OF CLOUDS AND LGT RAIN IN THE DEFORMATION ZONE ON
FRIDAY...WITH TEMPS FALLING BACK TO 55-65F. THE ECMWF SOLN WOULD
LINGER LIGHT RAIN OVER THE AREA /ESP IN THE EAST/ ON
SATURDAY...BUT DID NOT FULLY BUY-INTO THIS GIVEN HOW STRONG IT WAS
WITH THE CLOSED H5 LOW COMPARED TO THE OTHER GLOBAL GUIDANCE.
CANADIAN HIGH PRES EXTENDING SWD FROM NUNAVUT INTO THE UPPER
MIDWEST WILL SHIFT EWD ACRS THE GREAT LAKES AND EVENTUALLY TAKE UP
RESIDENCE OVER THE NORTHEAST BY MEMORIAL DAY. ENS DATA CONTINUES
TO SHOW NEGATIVE THERMAL/MOISTURE ANOMS SUPPORTING AN UNSEASONABLY
COOL AND DRY WEEKEND WITH THE POTENTIAL FOR FROST IN THE NRN AND
WRN MTNS SAT/SUN AM. THE GROWING SEASON IS UNDERWAY IN THIS AREA
/AS OF MAY 20TH/ AND THEREFORE WILL CONTINUE TO MENTION FROST IN
HWO. ELSEWHERE LOW TEMPS WILL BE CHILLY BY LATE-MAY STANDARDS...BUT
NOT QUITE COLD ENOUGH FOR FROST.

Q-STNRY/WARM FRONTAL ZONE INITIALLY CENTERED FROM IA-WV SHOULD
SLOWLY RETURN NWD THROUGH THE OH VLY EARLY NEXT WEEK. GFS/EC DIFFS
IN THE PATTERN EVOLUTION CONTINUE INTO THE END OF THE MEDIUM RANGE
PARTICULARLY UPSTREAM. IN GENERAL...THERE SHOULD BE A GRADUAL
EARLY-MID WEEK WARMING TREND WITH HTS RISING AS THE UPPER TROUGH
CONTINUES TO MOVE AWAY FROM THE NORTHEAST.
-- End Changed Discussion --

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
NOT A LOT OF CHANGE. STILL AN ISOLATED STORM POSSIBLE NEAR
THE NY BORDER OVERNIGHT. ALSO MAYBE A BRIEF SHOWER CLOSE
TO JST...LEFT OUT THE FCST FOR NOW.

EARLIER DISCUSSION BELOW.

MAIN FRONT AND ACTION ACROSS NY STATE...TOOK MENTION OF SHOWERS
AND STORMS OUT OF ALL SITES BUT BFD. LEFT VCSH IN BFD UNTIL 03Z.

SOME FOG LATER...BASED MAINLY ON WHAT WENT ON LAST NIGHT.

NOT SEEING MUCH DIFFERENCE FOR WED...VERY SIMILAR TO TODAY...
WILL BE IN THE WARM SECTOR...WITH NOT MUCH GOING ON.

MORE IN THE WAY OF WIDESPREAD SHOWERS AND STORMS LATER THU
INTO THU NIGHT. COULD BY BUSY ACROSS THE FAR SE THU NIGHT...
IF A WAVE FORMS ON THE FRONT.

COOLER AND BREEZY FOR FRIDAY INTO SUNDAY...AS A STRONG COLD
FRONT DROPS SE OF PA.

HO
.OUTLOOK...
THU...SCT THUNDERSTORM IMPACTS POSSIBLE...MAINLY IN THE PM.
FRI-MON...NO SIG WX EXPECTED.

&&

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

&&

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