FXUS61 KCTP 090942
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
442 AM EST WED DEC 9 2009
.SYNOPSIS...
STRONG LOW PRESSURE WILL PASS NORTH OF PENNSYLVANIA LATE
TODAY...PUSHING A SHARP COLD FRONT THROUGH THE STATE. A BROAD
UPPER LEVEL TROUGH WILL SET UP OVER THE NORTHERN CONUS THROUGH
SATURDAY...THEN LIFT OUT BY LATE IN THE WEEKEND. A SHORTWAVE WILL
APPROACH FROM THE WEST AROUND NEXT TUESDAY...BRINGING THE NEXT
CHANCE OF WIDESPREAD PRECIPITATION.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
SPOTTER REPORTS INDICATE A WIDE SWATH OF 3-6 INCH SNOW OCCURRED
ACROSS MUCH OF CENTRAL PA WITHIN THE LAST 12 HRS IN REGION OF
STRONG WAA/ISENTROPIC LIFT. HOWEVER...CHANGEOVER RAPIDLY ADVANCING
NORTHWARD AT THIS HOUR WITH ARRIVAL OF LOW LVL JET AND WARMING
ALOFT. SFC OBS INDICATE TEMPS STILL A FEW DEG BLW 0C OVR THE
HIGHER TERRAIN OF THE ALLEGHENIES. KJST REPORTING MODERATE FZRA AT
09Z...AND WITH PLENTY OF PRECIP UPSTREAM...A SIG ICE ACCRETION
STILL APPEARS ON TRACK FOR THE LAURELS. LATEST RUC13/NAM12 SUGGEST
SFC TEMPS WILL CREEP ABV FREEZING EVEN OVR THE RIDGETOPS BTWN 12Z-15Z.
EAST OF THE MTNS...SFC TEMPS ALREADY NEAR OR ABV 0C...SUGGESTING
MAINLY RAIN WILL FALL FOR THE BALANCE OF THIS EVENT. HOWEVER...WILL
LEAVE CURRENT WARNING/ADVISORY CONFIGURATION IN PLACE FOR NOW...AS
TEMPS WILL BE SLOW TO RISE AND ROAD CONDS LIKELY TO REMAIN POOR
FOR SEVERAL MORE HOURS.
ENSEMBLE DATA INDICATING SURGING PWATS OVR THE LOWER SUSQ VALLEY
AT NOSE OF LL JET BTWN 09Z-15Z...WHICH IN COMBINATION WITH
UPSTREAM RADAR DATA...SUPPORTS A PERIOD OF HVY RAIN DOWN THERE
THIS MORNING. LATEST ENS PLUMES SUGGEST RAIN TOTALS APPROACHING
FFH/FFH VALUES...SO HAVE ISSUED A FLOOD WATCH ACROSS OUR SE
ZONES.
DRY SLOT...CURRENTLY OVR THE OHIO VALLEY...WILL PUSH INTO CENTRAL
PA BY LATE AM...SHUTTING OFF THE STEADY PRECIP. HOWEVER...VIGOROUS
SHORTWAVE AND ASSOCIATED SHARP COLD FRONT WILL PUSH THRU THE AREA
LATE TODAY. MARGINAL INSTABILITY AHEAD OF THIS FEATURE...COMBINED
WITH STRONG LG SCALE FORCING...SUGGEST A FEW GUSTY TSRA WILL BE
POSSIBLE...SUCH AS IS CURRENTLY OCCURRING OVR INDIANA ATTM.
HAVE POSTED A WIND ADVISORY FOR THE ALLEGHENY MTNS LATE
TDY/TONIGHT...WHERE BUFKIT PROFILES SHOW THE INCREASINGLY DEEP
MIXED LAYER TAPPING 50-60 KT WINDS FROM JUST A FEW THOUSAND FEET
ABOVE THE SURFACE. HAVE OPTED TO LEAVE AREAS EAST OF THE MTNS OUT
OF ADVISORY FOR NOW...WHERE PROFILES NOT QUITE AS IMPRESSIVE.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM THURSDAY/...
STRONG/GUSTY WESTERLY FLOW WILL ADVECT COLDEST AIRMASS OF THE
SEASON INTO PA TONIGHT. WIND CHILL READINGS LIKELY TO DIP INTO THE
TEENS...WITH SINGLE DIGITS OVR THE ALLEGHENIES.
BLYR FLOW FROM THE WSW SHOULD KEEP FOCUS OF LAKE EFFECT SNOW
NORTH OF THE BORDER...WHERE AN INTENSE SINGLE LES BAND SHOULD
AFFECT WESTERN NY STATE. FURTHER SOUTH...OROGRAPHIC EFFECTS WILL
PRODUCE A CHC OF -SHSN ACROSS THE ALLEGHENIES OF PA WITH LIGHT
ACCUMS OF LESS THAN AN INCH MOST LIKELY.
MAINLY DRY/COLD PATTERN SHOULD HOLD THROUGH THURS...AS LAKE EFFECT
REMAINS FOCUSED NORTH OF BORDER. ENS MEAN 850 TEMPS ARND -14C
SUGGEST HIGHS FROM THE 20S MTNS...TO L30S SUSQ VALLEY. A GUSTY
WEST WIND WILL CONTINUE TO MAKE IT FEEL EVEN COLDER WITH WIND
CHILLS IN THE TEENS/20S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
ACTIVE WEATHER PATTERN CONTINUES THROUGH THE PERIOD.
CORE OF COLD SHOULD MOVE OVR THE REGION THURS NITE/FRIDAY...WHEN
ENS MEAN 850 TEMPS DIP AS LOW AS -20C. WINDS SHOULD REMAIN UP...SO
DON/T SEE SUB ZERO LOWS. HOWEVER...TEMPS LIKELY TO STRUGGLE TO GET
OUT OF THE TEENS FRIDAY AFTN OVR THE HIGH TERRAIN...WHILE EVEN THE
LOWER SUSQ LIKELY TO REMAIN BLW FREEZING. BLYR FLOW STILL APPEARS
TO FAVOR SINGLE BAND JUST NORTH OF THE BORDER...ALTHOUGH IT MAY
GRAZE WARREN COUNTY FRI/FRI NITE.
SFC RIDGE SLIPS IN FROM THE SOUTH SAT/SUN...BUT LOOKS LIKE IT WILL
BREAK DOWN QUICKLY UNDER PROGRESSIVE FLOW. SHORTWAVE SLIDES NE
FROM GULF OF MEXICO STATES AND COULD POTENTIALLY BRING SOME LIGHT
SNOW TO SOUTHERN PA SAT NIGHT/SUN. ALTHOUGH LATEST NAEFS/OPER EC
SUGGEST THIS IS AN INCREASINGLY UNLIKELY EVENT.
SHORTWAVE APPROACHING FROM THE N PLAINS WILL BRING NEXT CHC OF
WIDESPREAD PRECIP ARND TUESDAY OF NEXT WEEK. CURRENT GEFS/OPER EC
TRACK SFC LOW WEST OF PA...INDICATING A BRIEF WARM UP...FOLLOWED
BY SHRASN WITH FROPA.
&&
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
WIDESPREAD IFR/LIFR EXPECTED AT ALL AIRFIELDS OVERNIGHT IN VARYING
COMBINATIONS OF SNOW...SLEET AND FREEZING RAIN THEN CHANGING TO ALL
RAIN AFTER SUNRISE WEDNESDAY. IN ADDITION TO POOR CIGS AND
VSBYS...POSSIBILITY OF LLWS WILL BE PRESENT OVERNIGHT AT ALL
AIRFIELDS WITH STRONG SERLY WINDS AT THE SFC SWITCHING TO STRONG
SRLY ABOVE THE DECK.
WITH VERY STRONG DYNAMICS...AND SW FLOW...SOME CHC FOR JUST A SCT
DECK OF CLDS BY LATE MORNING...OR EARLY AFT...GIVEN DRY SLOT.
WINDS WILL SHIFT TO THE NW LATE THIS AFTN...BUT WITH SUCH DEEP
SYSTEMS...WINDS WILL TEND MORE FROM THE SW THAN OFTEN FCST. THIS
ALONG WITH A LOT OF DIRECTIONAL SHEAR...LAKE EFFECT WILL BE SLOW
TO GET INTO THE AREA IN THE TIME FRAME FROM LATE WED INTO THU AND
FRI. BEST CHC WILL BE LATER ON THU INTO FRIDAY ACROSS THE MTS.
OUTLOOK...
WED NIGHT/THUR...MVFR/IFR NORTH AND WEST IN SNOW SHOWERS
MAINLY IN THE MOUNTAINS. STRONG WESTERLY WNDS.
FRI/FRI NIGHT...MVFR (AND LOCALIZED IFR) WEST WITH SCATTERED
SNOW SHOWERS IN MTNS OF NORTHERN AND WESTERN PA. VFR MOST OF
CENTRAL AND EAST. STILL WINDY.
SAT/SUN...VFR...POSSIBLY DECREASING TO IFR/MVFR SHOULD A SYSTEM
ALONG THE CAROLINA COAST EDGE A LITTLE FARTHER NW...AND PROVIDE
THE REGION WITH LIGHT SNOW.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 AM EST THIS MORNING FOR
PAZ004-010>012-017>019-025>028-034>037-041-042-045-046-049>053-
056>058-063.
WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 6 AM EST THURSDAY
FOR PAZ004>006-010-011-017-024-033.
WINTER STORM WARNING UNTIL 11 AM EST THIS MORNING FOR PAZ005-
006-024-033.
FLOOD WATCH THROUGH THIS AFTERNOON FOR PAZ059-064>066.
&&
$$
SYNOPSIS...FITZGERALD
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD
LONG TERM...FITZGERALD/RXR
AVIATION...GARTNER/MARTIN
