FXUS62 KILM 071954
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
254 PM EST MON DEC 7 2009
.SYNOPSIS...
SOMEWHAT UNSETTLED CONDITIONS WILL PERSIST THROUGH WEDNESDAY AS A
WARM FRONT MOVES ACROSS THE REGION LATE TUESDAY FOLLOWED BY A
STRONG COLD FRONT LATER WEDNESDAY. HIGH PRESSURE WILL DOMINATE THE
WEATHER THURSDAY AND FRIDAY FOLLOWED BY A RETURN OF UNSETTLED
CONDITIONS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 2:45 PM MONDAY...IMAGERY THIS AFTERNOON SHOWS SWIFT WSW WIND
FLOW ALOFT TRANSPORTING HIGH CLOUDS OVER THE REGION AHEAD OF A FEW
IMPULSES ALOFT TRACKING INTO THE APPALACHIANS...WITH A PERSISTENT
MARINE LAYER HANGING ON ACROSS THE FORECAST AREA. THIS CLOUD DECK
THROUGH THE DAY HAS DISPLAYED VARIABLE TRENDS OF BREAKS AND FILLING
MAKING NEAR TERM SKY COVER GRIDS NEARLY NIGHTMARISH. APPEARS MOSTLY
CLOUDY CONDITIONS WILL PERSIST INTO EVENING HOURS. A LOW AMPLITUDE
TROUGH AXIS JUST BEYOND THE 20NM WATERS...WITH SOME VERY LIGHT
RETURNS MOVING NORTH TOWARD THE CAPE FEAR REGION. THIS COULD BRING
SPOTTY DRIZZLE TO THE NC COAST INTO THE LATE AFTERNOON AND EARLY
EVENING BUT MEASURABLE RAIN LOOKS LIKE A STRETCH AT THIS TIME.
THE ECHO COVERAGE APPEARS RIGHT NOW TO REPRESENT A COMPROMISE
BETWEEN THE NAM AND GFS PCPN FIELDS. NO PCPN IN THE FORECAST RIGHT
NOW FOR THE NEAR TERM...BUT THIS MAY NEED TO BE INCLUDED IF THE
ECHOS HOLD TOGETHER BEFORE THE EXPECTED DEPARTURE OF THE COASTAL
TROUGH LATER THIS EVENING.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 2:45 PM MONDAY...LATEST FORECAST MODELS REMAIN CONSISTENT WITH THE
OVERALL SCENARIO THROUGH THE SHORT TERM PERIOD WITH A
POTENT/VERTICALLY STACKED SYSTEM MOVING THROUGH THE CENTRAL U.S. THE
ASSOCIATED WARM FRONT WILL MOVE ACROSS OUR AREA TUESDAY EVENING.
BOTH THE NAM AND GFS ARE TRENDING DRIER WITH THE ISENTROPIC LIFT
WITH THIS FEATURE. MAINTAINED THE LIKELY TO CATEGORICAL POPS HOWEVER
AS MOST IF NOT ALL AREAS SHOULD SEE SOME MEASURABLE RAIN WHILE
CUTTING BACK ON THE QPF AMOUNTS. A SECOND ROUND OF SHOWERS AND
POSSIBLY THUNDERSTORMS WILL MOVE ACROSS THE AREA MIDDAY WEDNESDAY
ASSOCIATED WITH THE TRAILING COLD FRONT. SPC HAS THE AREA
HIGHLIGHTED WITH SEE TEXT AS THERE IS AT LEAST SOME SEVERE POTENTIAL
WITH THE FRONT.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 2:45 PM MONDAY...HIGH PRESSURE BUILDS IN FROM THE WEST THROUGH
THE PD. EARLY THURSDAY THERE WILL STILL BE A LINGERING PINCH IN THE
GRADIENT BUT IT WILL QUICKLY EASE AS THE CENTER OF THE SURFACE RIDGE
NEARS. THE EASTWARD TRANSLATION OF THE HIGH WILL BRING VEERING WINDS
LOCALLY INTO FRIDAY AND SATURDAY. A DEVELOPING COASTAL TROUGH WILL
STRENGTHEN THE NORTHEASTERLY GRADIENT WINDS ON SATURDAY WITH AN
INCREASE IN SHORT PERIOD WIND WAVES IN TANDEM. SEAS COULD BUILD HIGH
ENOUGH TO REQUIRE SMALL CRAFT ADVISORY BY SATURDAY AFTERNOON.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
AS OF 18Z THE FLO TERMINAL IS EXPERIENCING MVFR CEILINGS WHILE THE
REMAINING TERMINALS HAVE CEILINGS RANGING FROM 3K-3.5K AT CRE/MYR
AND LBT...TO 5K AT ILM. IFR CEILINGS SOUTH OF THE TERMINALS AT
GEORGETOWN AND CHARLESTON HAVE LIFTED TO MVFR AT 17Z SO THE CHANCE
OF ANY IFR IS VERY LOW. VISIBLE SATELLITE IMAGES SHOW LOW CLOUDS
ERODING FROM SOUTH TO NORTH WELL SOUTH OF THE TERMINALS...WITH
SOME HOLES DEVELOPING IN THE LOW STRATO-CU LAYER LOCALLY BETWEEN
MYR AND FLO/LBT. RADAR INDICATES PATCHY LIGHT RAIN MAINLY EAST OF
FLO AND LBT.
DECREASING OMEGAS AND INCREASED DRYING IN THE MID LEVELS SUGGEST ANY
PRECIPITATION WILL SOON END. COPIOUS AMOUNTS OF MOISTURE SHOULD
REMAIN TRAPPED NEAR AND BELOW A LOW LEVEL INVERSION LOCATED
2K-3.5K...BUT DIURNAL EFFECTS AND RECENT TRENDS SUGGEST CLOUDS AT
THIS LEVEL MAY SCATTER OUT IN THE NEXT SEVERAL HOURS. STILL...TEMPO
MVFR CEILINGS 2-3K MAY STILL HAVE A CHANCE TO OCCUR FOR THE NEXT
SEVERAL HOURS ESPECIALLY AT FLO/MYR AND CRE.
EXPECT SCATTERED TO BROKEN CLOUDS AT 2-3K TO RE-DEVELOP AT THE
COASTAL TERMINALS THIS EVENING...WHILE FLO/LBT WILL HAVE SCATTERED TO
BROKEN MID-LEVEL CEILINGS AS MOISTURE AGAIN INCREASES FROM THE
WEST AT THAT LEVEL. WINDS WILL BE BECOME LIGHT AND VARIABLE. MOS
DATA IS SUGGESTING IFR/LIFR CEILINGS DEVELOPING LATE THIS EVENING
INTO THE EARLY MORNING HOURS AT THE COASTAL TERMINALS...MOST
LIKELY DUE TO THE PROXIMITY TO A COASTAL TROUGH. CEILINGS ARE
INDICATED TO IMPROVE TO MVFR TOWARDS SUNRISE AS WINDS INCREASE IN
RESPONSE TO HIGH PRESSURE RE-ESTABLISHING ITSELF AND PUSHING THE
COASTAL TROUGH AWAY FROM THE COASTAL TERMINALS. FLO/LBT SHOULD
EXPERIENCE TEMPO MVFR VISIBILITIES OVERNIGHT. MVFR CEILINGS WILL
DEVELOP IN THE MID TO LATE MORNING AT ALL TERMINALS.
EXTENDED OUTLOOK...IFR POSSIBLE TUESDAY NIGHT AND WEDNESDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 2:45 PM MONDAY...SEAS RUNNING 3-4 FEET ACROSS THE WATERS...EXCEPT
CLOSER TO 2 FEET NEAR SHORE SOUTH OF CAPE FEAR. THIS SHOULD HOLD
OVERNIGHT WITH AN INCREASE IN NORTHERLY FLOW EXPECTED MAINLY NEAR
OR JUST AFTER DAYBREAK TUESDAY.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 2:45 PM MONDAY...NE FLOW INITIALLY WILL QUICKLY VEER TO
SOUTHEASTERLY AND EVENTUALLY TO THE SOUTHWEST BY WEDNESDAY MORNING
AS A WARM FRONT MOVES ACROSS LATE TUESDAY INTO WEDNESDAY MORNING.
THE GFS SHOWS A LOW LEVEL JET OVER 80 KNOTS AT 850MB MOVING ACROSS
WITH THE COLD FRONT WEDNESDAY WITH OVER 60 KNOTS AT 925MB. HOWEVER
WITH STRONG WARM AIR ADVECTION...THERMAL PROFILES ARE NOT FAVORABLE
FOR GOOD MOMENTUM TRANSFER. INCREASED SURFACE WINDS TO 30-35 KNOTS
BUT SUBSEQUENT SHIFTS WILL NEED TO MONITOR TRENDS CLOSELY TO SEE IF
A GALE WARNING WILL BE NECESSARY. SEAS INCREASE MARKEDLY FOLLOWING
THE SAME TRENDS WITH THE LATEST SWAN MODEL ADVERTISING SOME DOUBLE
DIGIT SEAS JUST OUTSIDE OF THE ZONES WEDNESDAY. ELEMENTS WILL
GRADUALLY SUBSIDE LATE WEDNESDAY AND THURSDAY IN THE WAKE OF THE
COLD FRONTAL PASSAGE.
LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 2:45 PM MONDAY...WITH THE EXCEPTION OF THURSDAY THE GENERAL THEME
OF THE LONG TERM WILL BE TEMPERATURES THAT ARE BELOW CLIMO....ESP
DAYTIME HIGHS. COLD AIR WEDGE BUILDING IN PLACE THURSDAY THROUGH
FRIDAY WITH THE THERMAL ADVECTION STRONGEST ON FRIDAY. MID LEVEL
FLOW QUITE ZONAL SO CLOUD COVER SHOULD BE MINIMIZED THURSDAY AND
FRIDAY. SOUTHERN STREAM FEATURE WILL DEVELOP AND MOVE ACROSS THE
GOMEX AND SHOULD BRING SOME INCREASING MOISTURE AND EVENTUALLY RAIN
CHANCES OVER THE WEEKEND. MODEL GUIDANCE HAS BEEN QUESTIONABLE PAST
FEW RUNS WITH THE SENSE OF TIMING BUT SOME CONVERGENCE IN SOLUTIONS
IS NOW BECOMING APPARENT. THE BEST CHANCES FOR OVERRUNNING PRECIP
APPEARS TO BE SATURDAY NIGHT INTO EARLY SUNDAY. THE ECMWF IS SHOWING
ITS TYPICAL BIAS IN DEPICTING AN APPRECIABLE QPF EVENT BUT THE GFS
LOOKS MUCH MORE REASONABLE IN ITS SUPPRESSION OF THE BIGGEST RAINS
TO OUR SOUTH (EVEN THOUGH ITS TIMING CONTINUES TO BE TOO FAST).
BARRING ANY ADDITIONAL TWEAKS TO TIMING...DRY AIR SHOULD PUSH IN
QUITE STRONGLY AS SUNDAY PROGRESSES. BROAD ZONAL FLOW WILL HELP
PREVENT ANY SIGNIFICANT COLD AIR ADVECTION BEHIND THIS SYSTEM AND
TEMPERATURES MONDAY MAY REMAIN STATUS QUO...IN THE BELOW CLIMO RANGE.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...SHK
NEAR TERM...MJC
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...MRR
