FXUS61 KCTP 071206
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
706 AM EST MON DEC 7 2009
.SYNOPSIS...
HIGH PRESSURE OVER DELMARVA WILL MOVE OFF THE MID-ATLANTIC COAST
WHILE A WEAK LOW PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES AND
UP THE SAINT LAWRENCE RIVER VALLEY BY MONDAY NIGHT. A MOISTURE-
STARVED COLD FRONT TRAILING THE LOW WILL SWEEP ACROSS THE REGION
AND MAY BRING SOME SCATTERED SNOW SHOWERS TO THE ALLEGHENIES THIS
AFTERNOON AND TONIGHT. HIGH PRESSURE WILL RETURN FOR TUESDAY BEFORE
A SIGNIFICANT STORM SYSTEM LIFTS NORTHEASTWARD FROM THE CENTRAL
U.S. AND BRINGS A WINTRY MIX OF PRECIPITATION TUESDAY NIGHT INTO
WEDNESDAY...FOLLOWED BY COLDER AIR FOR THE REMAINDER OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRES INITIALLY OVR THE DELMARVA WILL SLIDE OFF THE MID-ATLC
COAST IN ADVANCE OF WEAK LOW AND TRAILING COLD/OCCLD FNT MOVING
EWD ACROSS THE GREAT LKS/OH VLY THIS AFTERNOON. DESPITE DECENT
KINEMATIC FORCING ALOFT ASSOC WITH AN 100KT JET SURGING ENEWD FM
THE MS VLY...VERY LIMITED LLVL MSTR/LOW PWS SUPPORTS BARELY
MEASURABLE QPF WITH THIS SYS. THEREFORE WILL CONFINE CHC POPS ONLY
THE ALLEGHENIES...WHERE OROGRAPHICS WILL PROVIDE SOME ADDITIONAL
LIFT NEEDED TO PERHAPS SQUEEZE OUT A FEW TENTHS. POST-FNTL LK MSTR
TAP MAY TOO AID IN GENERATING SCT SNOW SHOWER ACTIVITY...ESP
HEADING INTO MON NGT.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
CONFIDENCE REMAINS VERY HIGH WITH MID-WEEK STORM...AND WINTER
HEADLINES WILL LIKELY BE NEEDED IN THE NEXT 24 HRS. TUE WILL BE
QUIET WITH WEAK SFC RIDGE PROVIDING ANTI- CYCLONIC FLOW IN THE
BNDRY LYR WITH P-CLOUDY SKIES FOR MUCH OF THE CWA. WEAK
DOWNSLOPING WILL PROVIDE FURTHER EROSION OF CLOUDS LEE- SIDE OF
THE ALLEGHENIES TUE. HIGH LVL MOISTURE QUICKLY POOLS NE AHEAD OF
DEVELOPING STORM TUE NGT.
PRECIP MOVES IN TUE NGT /POSSIBLY BEFORE 00Z WED IN THE SW/ AS A
WEAK FRONTAL BNDRY LIFTS NORTH AHEAD OF DEEPENING SURFACE LOW
WHICH WILL TRACK NE THROUGH OHIO VALLEY. CENTRAL PA WILL REMAIN ON
E SIDE OF THE LOW...WHICH WILL EVENTUALLY PUSH WARM AIR INTO THE
REGION. BUT TUE NIGHT WHEN PRECIP BEGINS TEMPS SHOULD BE COLD
ENOUGH TO START OFF AS SNOW/FREEZING RAIN AS SYSTEM TRENDING JUST
A BIT WARMER THAN IT LOOKED YESTERDAY...SO COULD SEE A COUPLE OF
INCHES ACCUMULATE IN THE NE WITH MAINLY A SNOW/FZRA MIX CENTRAL
AND SOUTH. BUT WARM AIR WILL STREAK IN AS TEMPS WARM ABV FREEZING
BY 12Z WED IN THE SOUTH AND A COUPLE OF HOURS LATER IN THE NORTH.
ENSEMBLES HAVE HELD ONTO QPF ARND .5 TO .8 INCHES. TROUGH DOES
BECOME MORE NEGATIVELY TILTED LATER WED INTO THU AS A COASTAL LOW
TRIES TO ORGANIZE OFF NEW ENGLAND COAST...BUT ENSEMBLE SUGGESTS
SFC VORT SHUD PASS NW OF THE CWA BY THEN. THIS COULD PROVIDE A
BREAK IN PRECIP WED AFTN AHEAD OF FRONTAL PASSAGE.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
FLOW REMAINS VERY PROGRESSIVE WITH SEVERAL GEFS MEMBERS
ADVERTISING A 130-150KT 300MB JET THUR/FRI. THIS SHUD PROVIDE A
GOOD SCENARIO IN THE BNDRY LYR FOR LES ACROSS THE NW MTNS/UPSLOPE
SNOW FOR LAUREL HIGHLANDS. 850MB TEMPS CONSIDERABLY COOLER AT -12
TO -14 DEG C THUR/FRI. ATTM FEEL GIVEN CONSID CLOUD COVER DURING
DAYLIGHT HOURS TEMPS WILL HOLD IN THE 20S/30S FOR THE END OF THE
WEEK...HOWEVER IF SKIES CAN CLEAR TEMPS WILL EASILY COOL
OVERNIGHT.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
VFR CIGS WITH LIGHT AND VARIABLE SFC WINDS WILL PREVAIL THROUGH
MID MORNING AS A MOISTURE STARVED WEATHER SYSTEM TRACKS EASTWARD
FROM THE OHIO VALLEY. ASSOCIATED WK SFC LOW LIFTING NEWD ACROSS
THE GRT LKS AND UP THE ST LAWRENCE VLY WILL PUSH A COLD/OCCLD FNTL
SYS THRU THE REGION BY TONIGHT.
CIGS SHOULD GRADUALLY LOWER THROUGHOUT THE DAY TO MOSTLY MVFR THIS
AFTERNOON AT JST/BFD AND CONTINUE TO DETERIORATE TONIGHT BCMG
MVFR/IFR IN SCT SHSN. CONFIDENCE IS FAIRLY HIGH WRT TO THE LOW CIG
RESTRICTIONS ESP POST FROPA AS LLVL FLOW BECOMES ALIGNED WITH THE
LAKE AND ASCENDS THE HIER TERRAIN. UNV/AOO/IPT SHUD STAY MVFR OR
BETTER WHILE MDT WILL REMAIN VFR.
HIGH PRES MOVES IN FOR TUE BUT LOW CLOUDS LKLY TO HANG TOUGH IN
THE WEST. SIGNIFICANT STORM SYSTEM FCST TO MOVE THROUGH THE GRT
LKS WILL BRING A MIXTURE OF PCPN TUE NGT INTO WED WITH WDSPRD IFR
LKLY. STRONG WINDS ALSO APPEAR A GOOD BET ON THURS THE ATTENDANT
COLD/OCCLD FNT RACES NEWD OFF THE ECOAST. NWLY FLOW IN THE WAKE OF
THIS SYS MAY KEEP REDUCED CIGS AND VSBYS ACROSS THE WESTERN HIGH
TERRAIN ALONG WITH SOME LAKE EFFECT SNOW SHOWERS.
OUTLOOK...
TUE...MVFR/IFR BCMG VFR NORTH/WEST. MVFR BCMG VFR CENTRAL/EAST.
TUENGT/WED...BCMG WDSPRD IFR IN SNOW/ICE. LLWS.
WEDNGT/THUR...MVFR/IFR WEST. IMPRVG CENTRAL/EAST. STRONG WSW WNDS.
FRI...MVFR WEST. VFR EAST.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LA CORTE/RXR
NEAR TERM...LA CORTE/RXR
SHORT TERM...RXR
LONG TERM...BEACHLER/RXR
AVIATION...DEVOIR/LAMBERT
