Weather data updated: 11:00:00 PM
000
FXUS61 KCTP 120145
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
845 PM EST THU MAR 11 2010
.SYNOPSIS...
A LARGE SLOW MOVING STORM OVER THE CENTRAL PLAINS WILL MOVE EAST
INTO THE CENTRAL APPALACHIANS...INDUCING A STRONG LOW PRESSURE
SYSTEM ALONG THE MIDDLE ATLANTIC COAST THIS WEEKEND. THIS SYSTEM
WILL LIKELY BE ACCOMPANIED BY HEAVY RAINFALL. THE COMBINATION OF
HEAVY RAIN AND SNOW MELT MAY RESULT IN FLOODING.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
REGIONAL RADAR LOOP SHOWING BAND OF LGT RAIN WORKING INTO
SOUTHWEST PA ALONG AXIS OF LOW LVL JET. LATEST SHORT RANGE MDL
DATA SUPPORTS LGT RAIN SPREADING NE ACROSS CENTRAL PA
OVERNIGHT...REACHING THE NE COUNTIES ARND 09Z. QPF AMTS SHOULD BE
LOW...AS BEST LG SCALE FORCING WILL REMAIN NR UPPER LOW OVR THE
GRT LKS AND AHEAD OF SHORTWAVE OVR THE COASTAL CAROLINAS.
HOWEVER...HAVE RAISED POPS TO NR 100 PCT OVR MOST OF CENTRAL AND
SOUTHERN PA BASED ON UPSTREAM RADAR AND 21Z SREF.
OVERCAST SKIES AND INCREASING LOW LVL MOISTURE SHOULD RESULT IN A
MILD NIGHT. BASED ON CURRENT DWPTS...EXPECT READINGS GOING NO
LOWER THAN THE L40S ACROSS THE N MTNS...TO U40S SOUTHERN HALF OF
THE STATE.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
FRIDAY WILL FINALLY BE THE CLOUDY DAY WE HAVE BEEN EXPECTING FROM
THIS PLODDING STORM THAT CONTINUES TO TAKE ITS TIME GETTING HERE.
MOIST EASTERLY FLOW SHOULD RESULT IN LOW CLOUDS AND OCCASIONAL LGT
RAIN/DRIZZLE. HOWEVER...LG SCALE FORCING LOOKS WEAK...SUGGESTING
PRECIP AMOUNTS WILL REMAIN ON THE LIGHT SIDE WITH THE BULK OF THE
RAINS HOLDING OFF UNTIL FRI NIGHT AND SAT.
CLOUD COVER AND OCCASIONAL LIGHT RAIN SHOULD HOLD TEMPS FROM RISING
MUCH FROM MORNING LOWS...RESULTING IN HIGH TEMPS SOME 10 TO 15 DEG
COOLER THAN TODAY. THE RECENT STRING OF FINE WEATHER WILL MOST
ASSUREDLY HAVE COME TO AN END.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
MID SHIFT DID UP QPF AMTS FOR THE STORM. WAS LOOKING CLOSE TO
2 INCHES YESTERDAY FOR MOST OF THE AREA...NOW LOOKIING AT
2 INCHES IN MOST AREAS...BUT AROUND 3 INCHES EASTERN PART
OF THE CWA. DID NOT CHANGE MUCH...DID EDGE UP HERE AND THERE.
STILL A LOT OF SPREAD IN THE QPF FIELDS. EASTERN AREAS NEAR
THERMAL RIDGE...A BIG CONCERN. STORM TOTAL QPF GRIDS IN 3
SECTIONS...ONE FOR FRIDAY...ANOTHER FOR SAT...AND ONE FOR
SUNDAY.
MAIN CHANGE WAS TO UP POPS SOME FRIDAY NIGHT ACROSS THE NORTH...
AND AGAIN IN A FEW AREAS SATURDAY NIGHT INTO SUNDAY...GIVEN THAT
STORM WILL LIKELY BE SLOW TO MOVE OUT...EVEN THOUGH QPF AMTS
MAY NOT BE THAT HIGH BY 12Z SUNDAY.
SUPPORT FOR HEAVY RAIN IS STRONG DYNAMICS...NEGATIVE TILT
TO THE SYSTEM...SECONDARY LOW...POSITION OF THERMAL RIDGE...
LLJ...AND ABNORMALLY STRONG EASTERLY FLOW.
SNOW IS NOT IN THE FCST ANYMORE...NOT REALLY COLD ENOUGH AT LOW
LEVELS. IT IS STILL POSSIBLE THAT SOME WET SNOW COULD MIX WITH
THE RAIN ACROSS THE LAURELS...BUT HARD TO SEE IT ACCUMULATING...
GIVEN SUCH STRONG FLOW FROM THE EAST AND NE.
DID NOT CHANGE TEMPS MUCH.
STILL LOOKING AT THE UPPER LEVEL RIDGE EXPANDING EASTWARD
EARLY NEXT WEEK...THUS LOOKING AT CLEARING SKIES AND NO PCPN
AFT 00Z TUE.
TEMPS FOR THE LATER PERIODS TYPICAL OF MID MARCH.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
STRATUS DECK BTWN 2-3KFT OVERSPREADING SOUTHEAST PA THIS EVENING
AS INCREASINGLY MOIST SE FLOW ENVELOPS THE AREA. LATEST RUC13 LOW
LVL RH SUGGESTS ALL CENTRAL PA TERMINALS WILL HAVE AT LEAST MVFR
CIGS BY LATE THIS EVENING...WITH IFR CIGS TO FOLLOW AFTER
MIDNIGHT. LGT RAIN WILL OVERSPREAD THE AREA FROM THE SOUTH
BEGINNING ARND 03Z ACROSS THE SOUTHWEST /JST/ AND REACHING THE
NORTHEAST /KIPT/ ARND 09Z.
MOIST EASTERLY FLOW WILL PRODUCE WIDESPREAD IFR CIGS WITH
OCCASIONAL -RA DURING FRIDAY. A MAJOR STORM IS EXPECTED TO FORM
OVER THE CAROLINAS SATURDAY BEFORE MOVING UP THE COAST AS A
DEVELOPING GALE. IT WILL CREATE WIDESPREAD IFR WITH RAIN AND AND
POSSIBLY EVEN EMBEDDED THUNDERSTORMS...FROM AFTER MIDNIGHT FRIDAY
THRU MUCH OF THE WEEKEND. STRONG EAST-SOUTHEAST FLOW WILL ALSO
SUPPORT LOCAL AREAS OF LLWS.
OUTLOOK...
SAT-SUN...GENERALLY IFR CIGS/VSBY OCNL RA.
MON...DRYING/IMPROVEMENT TO VFR PSBL.
TUE...NO SIG WX EXPECTED.
&&
.HYDROLOGY...
OBSERVATIONS SHOW SEVERAL INCHES OF WATER STILL LOCKED UP IN THE
SNOW PACK OVER SWRN PA. MODELS CONTINUE TO ZERO IN ON A LARGE AREA
OF 2 TO 4 INCH RAINS STARTING AFTER MIDNIGHT FRIDAY LASTING INTO
THE DAY SATURDAY...AND CENTERED ROUGHLY OVER THE AREA SOUTH OF
I-80.
COMBINATION OF SNOW MELT AND STORM RUNOFF WILL LEAD TO THE INCREASING
POTENTIAL OF FLOODING.
AT THIS TIME A FLOOD WATCH IS IN EFFECT FOR THE LAURELS WHERE
THERE IS THE MOST WATER REMAINING IN THE SNOW PACK...AND FLOODING
COULD ENSUE SIMPLY DUE TO SNOW MELT EVEN BEFORE THE BULK OF THE
RAIN ARRIVES.
THE WATCH IS STILL BEING CONSIDERED FOR EXPANSION...BUT WITH SOME
36-48 HOURS REMAINING BEFORE THE HEAVIEST RAINS ARRIVE...WILL
LIKELY HOLD OFF UNTIL LATER TODAY OR OVERNIGHT WHEN WE CAN FURTHER
ZERO IN ON THE HIGHEST THREAT AREAS.
WITH THE AMOUNT OF RAIN EXPECTED...AND SOME AREAS STILL HAVING
CONSIDERABLE AMOUNTS OF HIGH WATER CONTENT SNOW ON THE
GROUND...THIS HAS THE POTENTIAL TO BE A VERY DANGEROUS FLOODING
SITUATION DEVELOPING OVER THE NEXT COUPLE OF DAYS. PERSONS NEAR
FLOOD PRONE AREAS WILL WANT TO KEEP A CLOSE WATCH ON LATER
FORECASTS AND CHANGING WEATHER CONDITIONS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM FRIDAY EVENING THROUGH LATE SATURDAY NIGHT
FOR PAZ025>028-034>036-056>059-063>066.
FLOOD WATCH THROUGH LATE SATURDAY NIGHT FOR PAZ024-033.
&&
$$
SYNOPSIS...LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...LA CORTE/FITZGERALD
LONG TERM...MARTIN
AVIATION...LA CORTE/FITZGERALD
HYDROLOGY...LA CORTE
NWS CTP Office Area Forecast Discussion
