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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 220743
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
343 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.
BEHIND THE SECOND FRONT...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 --
REGIONAL RADAR SHOWS ISOLD SHOWERS/TSTMS MOVG ACRS THE NRN MTS IN
ASSOC WITH 35-40KT SWLY LLJ. THERE COULD BE A DIFFUSE SFC BNDRY
OR MSTR CONVERGENCE AXIS EXTENDING SWWD ALONG THE ALLEGHENY FRONT
FROM WEAK LOW OVER UPSTATE NY. SHOWER ACTIVITY INVOF NRN WV HAS
BEEN DISSIPATING OVER THE LAST 2 HOURS. ASIDE FROM A WDLY SCT
SHOWER OR ISOLD TSTM OVER THE N-CNTRL TO NERN ZONES...EXPECT A
MAINLY DRY PERIOD THROUGH THE PRE-DAWN HOURS INTO THE EARLY
MORNING...WITH SOME PATCHY FOG ACRS THE MID-LWR SUSQ VLY. TEMPS
WILL REMAIN VERY MILD WITH MORNING LOWS IN THE MID-UPR 60S.

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 CITY 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...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 POSSIBLE MCS OVER OH/LWR
MI/LAKE ERIE WITH PEAK INTENSITY 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 GREAT
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 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.

WINDS WILL SHIFT TO THE NNW INTO THE EARLY MORNING HOURS ON
FRIDAY. THIS WILL DIRECT MUCH COOLER AND DRIER AIR MASS TOWARD THE
REGION WHICH SHOULD ARRIVE AROUND DAYBREAK FRIDAY.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
BEHIND THE DEPARTING COLD FRONT...A STG AND LARGE ANTICYCLONE
SHOULD DOMINATE PATTERN IN THE FRI-MON TIMEFRAME...BUILDING SEWD
FROM NUNAVUT CANADA ACROSS THE GRT LKS INTO THE NORTHEAST. AN
UNSEASONABLY COLD/DRY AIRMASS WILL ACCOMPANY THE HIGH RESULTING IN
BELOW NORMAL TEMPS FOR MEMORIAL DAY WEEKEND. ECENS MOS DATA SHOWS
TEMPS ON FRI/SAT STRUGGLING TO CRACK THE 60F MARK LOCALLY...WITH
SEVERAL OPPORTUNITIES FOR A LATE-SEASON FROST OVER THE NRN MTNS
SAT/SUN/MON MORNINGS. HOWEVER CURRENT LOW TEMPS REMAIN ABOVE 40
FOR MOST OF THE REGION WITH THE EXCEPTION BEING ALONG THE NEW YORK
BORDER. WINDS SHOULD REMAIN GUSTY SATURDAY MORNING. THE BETTER
CHANCE FOR FROST WILL BE SUNDAY MORNING...TEMPERATURES WILL BE
SLIGHTLY WARMER BUT THE WINDS SHOULD BE LIGHT TO CALM. THERE
SHOULD BE A MODERATION INTO THE MIDDLE OF NEXT WEEK WITH TEMPS
GETTING BACK TO NEAR NORMAL AROUND 5/28.
-- End Changed Discussion --

&&

.AVIATION /06Z 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...CERU/STEINBUGL
AVIATION...LAMBERT/MARTIN