FXUS61 KCTP 300554
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1254 AM EST MON NOV 30 2009
.SYNOPSIS...
A WEAK LOW PRESSURE AREA MOVING ACROSS LAKE ONTARIO OVERNIGHT
WILL DRAG A TRAILING COLD FRONT ACROSS THE WESTERN PART OF
PENNSYLVANIA MONDAY MORNING...AND THROUGH THE SOUTHEAST COUNTIES
OF THE STATE MONDAY AFTERNOON. NUMEROUS SHOWERS...AND A FEW
PERIODS OF STEADY RAIN...WILL OCCUR ALONG AND AHEAD OF THIS
FRONT. COOLER AIR ARRIVES MONDAY NIGHT AND TUESDAY BEHIND THE
FRONTAL PASSAGE WITH RAIN CHANGING TO SNOW SHOWERS. HIGH PRESSURE
BRIEFLY RETURNS LATE TUESDAY INTO EARLY WED...BEFORE A DEEP STORM
MOVES NORTHWARD FROM THE GULF STATES. GUSTY WINDS AND HEAVY RAIN
WILL BE POSSIBLE ON THU...AS THIS STORM MOVES NORTHWARD INTO NEW
YORK STATE. COLDER TEMPERATURES...ALONG WITH SNOW SHOWERS...WILL
FOLLOW THIS STORM FOR THE LATER PART OF THE WEEK.
&&
.NEAR TERM /UNTIL 8 AM THIS MORNING/...
SFC LOW (APPROX 1002 MB) WAS MOVING EAST ACROSS LAKE ONTARIO
THIS EVENING WITH A COLD FRONT EXTENDING BACK ACROSS WRN LAKE ERIE
AND NW RN OHIO. THE RAIN SHOWERS WERE MOVING ENE AT ABOUT 40 MPH
AHEAD OF THIS FRONT...AND ARE AT LEAST A FEW HOURS FASTER THAN QPF
DEPICTED BY THE 18Z OPERATIONAL GUIDANCE AND 15Z SREFS (AND ALSO A
LITTLE HEAVIER ALONG THE LEADING EDGE).
THE STRONGEST LIFT...AND CORRESPONDING RAINFALL DISTRIBUTION WE
SEE ON THE REGIONAL RADAR MOSAIC ATTM APPEARS TO BEST REFLECT THE
UVVEL ALONG THE 300K ISENTROPIC SFC. UVVEL WITHIN THE 300-305K
THETA CHANNEL INCREASES SOMEWHAT OVERNIGHT...AND THIS LOW TO MID
LEVEL FORCING SHOULD OVERCOME THE FAIRLY LARGE T/TD SPREAD OF
14-17 DEG F CURRENTLY SEEN ACRS CENTRAL AND EASTERN PENN.
HOURLY RAINFALL AMOUNTS THIS EVENING HAVE RANGED FROM JUST A FEW
HUNDREDTHS ACROSS FAR SWRN PENN AND ERN OHIO...TO BETWEEN
0.05-0.10" FURTHER NORTH. EXPECT THE MAIN FOCUS OF THE RAINFALL TO
SHIFT TO THE CENTRAL AND SERN PART OF PENN (SE OF A LINE FROM
KJST...TO KUNV AND KAVP) BY 12Z MONDAY.
TEMPS LOOK LIKE THEY WILL MILD IN MOST AREAS OVERNIGHT.. HOWEVER...
COLD ADVECTION KICKS IN SHORTLY BEFORE DAYBREAK IN THE NW...WHERE
LOWS WILL BE IN THE MID 30S. MIN TEMPS ACROSS THE CENTRAL AND SE
ZONES WILL BE GENERALLY IN THE LOWER 40S...BUT COULD ON DIP TO THE
MID 4OS IN THE LARGER CITIES AND TOWNS IN THE LOWER SUSQ VALLEY.
&&
.SHORT TERM /8 AM THIS MORNING THROUGH 6 PM TUESDAY/...
STEADY...OR EVEN A SLIGHT FALL IN TEMPS WILL OCCUR ACROSS THE NW
MTNS FROM THEIR EARLY MORNING MAXS IN THE MID/UPPER 30S. THE MIDDLE
STRIPE OF COUNTIES WILL HAVE STEADY TEMPS OR ONLY A SLIGHT RISE
INTO THE MID 40S...BEFORE AN MID TO LATE AFTN FALL OCCURS. SE
SHOULD GET TO MAXES AROUND 10-11AM...THEN STAY FAIRLY STEADY IN
THE UPPER 40S TO AROUND 50F.
18 HOUR RAINFALL TOTALS WILL LIKELY BE TWD THE UPPER END OF 15Z
SREF VALUES (CLOSER TO THE WETTER OPERATIONAL GFS)...RANGING FROM
0.2 TO 0.4 ACROSS THE CWA. THE SLIGHTLY HEAVIER RAINFALL AMOUNTS
OF 3-4 TENTHS OF AN INCH WILL OCCUR ACROSS THE NRN AND WRN MTNS.
8H TEMPS DROP FM +3C IN THE HRS BEFORE SUNRISE IN THE NW TO ONLY
-6C BY THE END OF THE DAY. THEY WILL ALSO FALL ABOUT 10C FM 12Z
MON TO 00Z TUE IN THE FAR SE. THUS...BLUSTERY WINDS AND COOLER -
BUT NOT ABNORMAL - TEMPS EXPECTED MON NIGHT. THE SHRA IN THE WRN
HIGHLANDS MON AM WILL TAPER OFF THEN PERHAPS MIX WITH AND CHANGE
TO SNOW BY THE END OF THE DAY. THE REST OF THE REGION WILL MOST
LIKELY WAIT UNTIL MON NIGHT TO COOL ENUF FOR ANYTHING THAT FALLS
TO BE SN. WITH SHORT FETCH OFF THE LAKE MON AFTN AND
EVENING...EXPECT LITTLE/NON- CONSISTENT ACCUMS AND WILL NOT
MENTION ACCUMS UNTIL THE NIGHT TIME PD. EVEN THEN...JUST AN INCH
OR TWO IS LIKELY IN THE NW AS FLOW BACKS TO THE W BY 12Z TUE.
UPSLOPE AREAS OF THE LAURELS COULD GET AN INCH OR TWO AS
WELL...BUT MOST VLY LOCS WILL JUST DUST.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
VERY LITTLE CHANGE FROM WHAT I SAW YESTERDAY.
BY TUE AFTERNOON...WINDS BACK TO THE SW...AND TEMPS START TO WARM.
FOR THE MOST PART...WED STILL LOOKING DRY DURING THE DAY ON WED.
I DID BRING SOME RAIN INTO THE AREA WED AFT...GIVEN HOW FAST THE
GFS IS AND OTHER OFFICES. THE NAM IS AT LEAST 8 HOURS SLOWER.
THE MODELS HAVE BEEN HAVING A HARD TIME WITH THE START TIME.
AS WAS THE CASE YESTERDAY...DECIDED TO LEAVE SOME SNOW IN
WED NIGHT INTO THU. STORM TRACK STILL TRENDING FURTHER WEST...BUT
NOT CLEAR CUT YET.
STILL THINK SYSTEM WILL BE WEAKER AND FASTER EAST THAN SOME MODELS
HAVE IT...BUT STILL EXPECT AN INLAND TRACK. ALSO THERE IS THE
ISSUE OF SPEED OF THE SYSTEM. LEFT THUNDER IN ACROSS THE SE WED
NIGHT AND EAST ON THU...EXPECT AN INTENSE DEWPOINT...WARM
FRONT...TO SET UP ACROSS THE EASTERN PART OF THE CWA OR JUST EAST
OF IT...AND WITH STRONG DYNAMICS...THINK HEAVY DOWNPOURS AND
THUNDER WILL BE POSSIBLE. RIVERS NOT REAL HIGH...AND SPEED OF THE
SYSTEM SHOULD KEEP FLOOD THREAT DOWN. THE LEADING EDGE OF DRY AIR
ALOFT ON THU COULD RESULT IN STRONG WINDS...SOMETHING TO WATCH
THU AFT.
LOOKS LIKE FLOW STAYS SW ALOFT ON THU NIGHT...THUS LAKE EFFECT
WILL BE MAINLY WEST OF THE MTS PRIOR TO FRIDAY MORNING. ANOTHER
SHORT WAVE POSSIBLE FRIDAY EVENING MAY LINGER SOME LAKE EFFECT
INTO SATURDAY MORNING.
MODELS NOW START TO WARM THINGS UP ON SUNDAY INTO MONDAY. WENT
WITH CHC OF SHOWERS WESTERN AREAS. MOST LIKELY WOULD BE RAIN...
BUT WENT WITH RAIN AND SNOW FOR NOW...GIVEN MIN TEMP FCST.
MEAN TROUGH TOO FAR WEST TO KEEP IT COLD HERE...MORE LIKE AN
UP AND DOWN PATTERN WITH SOME CHC FOR PCPN NOW AND THEN.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
CIGS WILL REMAIN REDUCED ACROSS THE ALLEGHENY AIRFIELDS...WITH
MAINLY MVFR TO IFR CONDS EXPECTED BY 10Z. DOWNSTREAM ACROSS THE
SUSQ-VALLEY AIRFIELDS MOISTURE IS SLOWLY LOWERING CIGS TO
MVFR...HOWEVER THINK MDT WILL HOLD AT VFR CONDS THRU MUCH OF THE
OVERNIGHT. SHRA WILL REMAIN LGT FOR ALL SITES...PSBLY JUST A FEW
SPRINKLES FOR MDT. FLOW TURNS NWSTRLY AND TEMPS STEADILY
FALL...BRINGING THE CHC FOR SN TO BFD BY 18Z. JST WILL BE ALL
RAIN IN THE AM...THEN MAY SEE A BREAK UNTIL THE EVENING WHEN SCT
SHSN BECOME PSBL.
OUTLOOK...
TUE...IFR/MVFR W IN POST FRONTAL SHSN. VFR E.
WED...VFR.
WED PM-FRI...MVFR TO IFR CIGS. LGT SHSN NW/RA CENT AND SE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...LAMBERT/MARTIN
NEAR TERM...LAMBERT
SHORT TERM...DANGELO
LONG TERM...MARTIN
AVIATION...BEACHLER
