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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 040437
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1137 PM EST MON MAR 3 2014

.SYNOPSIS...
A STRONG COLD FRONT WILL CONTINUE TO PUSH OFFSHORE TONIGHT...WITH
MUCH COLDER AND BLUSTERY CONDITIONS EXPECTED TONIGHT AND TUESDAY.
SOME LIGHT FROZEN PRECIPITATION IS ALSO POSSIBLE. COLD HIGH
PRESSURE WILL WEDGE ACROSS THE AREA INTO THURSDAY...CONTINUING
COOL AND UNSETTLED WEATHER AS A WAVE OF LOW PRESSURE MOVES ALONG
THE COAST. A STRONGER LOW PRESSURE SYSTEM WILL TRACK UP THE COAST
THURSDAY INTO FRIDAY WITH POSSIBLY HEAVY RAINFALL. HIGH PRESSURE
WILL BUILD BACK INTO THE AREA BEHIND THIS SYSTEM FRIDAY AND INTO
THE WEEKEND. ANOTHER COLD FRONT WILL CROSS THE AREA SUNDAY NIGHT.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
-- Changed Discussion --
AS OF 1045 PM MONDAY...CONTINUED UPDATES TO THE HOURLY GRIDS HAVE
BEEN APPLIED AND UPLOADED...PARTICULARLY RELATED TO THE
CONTINUED ADVECTION OF THE ARCTIC AIR ACROSS THE ILM CWA.
LATEST PCPN COVERAGE AND INTENSITY ACROSS THE ILM CWA HAS
DECREASED AND DIMINISHED DURING THIS LATE EVENING. FOR THE
REMAINDER OF THE OVERNIGHT...THE FA WILL BE LOOKING AT A CONTINUED
POST FRONTAL STRATIFORM CLOUD DECK. THE ARCTIC/COLD AIR DEPTH TO
REMAIN QUITE SHALLOW ACROSS THE FA DURING ITS SHORT TENURE ACROSS
THE ILM CWA. LOW LEVEL MOISTURE TO REMAIN ACROSS THE FA OVERNIGHT
...WITH MINIMAL DYNAMICS TO PRODUCE ANY ORGANIZED PCPN...OTHER
THEN THE LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE WITH
MINIMAL IF ANY ACCRUAL OR ACCRETION TO OCCUR. CONTINUED RADAR
ECHOES ACROSS THE ILM CWA...AND LATEST TEMPS FROM SFC OBS
INDICATING PCPN FALLING AS PATCHY ZR- OR XL-...WITH ICE PELLETS
IE. SLEET...ALSO POSSIBLE WHERE THE SFC BASED ARCTIC AIR IS
DEEPER IN DEPTH. OVERALL...HAVE CONTINUED TO BACK OFF ON PCPN
COVERAGE BUT WILL CONTINUE TO INDICATE THE THREAT FOR
WINTRY PCPN OVER PORTIONS OF THE ILM CWA.

FOR THE CLIMATIC DAY...MARCH 3RD 2014...THE LOW TEMPERATURES FOR
TODAY ACROSS THE ILM CWA HAVE BEEN CONTINUALLY RE-SETTING TO A
NEW LOW TEMP FOR THE DAY AS ARCTIC AIR CONTINUES TO ADVECT ACROSS
THE FA THE REMAINDER OF THIS EVENING...AND OVERNIGHT.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
-- Changed Discussion --
AS OF 300 PM MONDAY...A HIGHLY UNSETTLED PERIOD OF WEATHER
THROUGH MID- WEEK AS AN ARCTIC FRONT STALLS OFFSHORE WHILE WAVES
OF LOW PRESSURE MOVE ALONG IT.

PERIOD BEGINS WITH A WEDGE OF HIGH PRESSURE BANKED ALONG THE EAST
COAST BEHIND AN ARCTIC FRONT STALLED JUST OFFSHORE. ALOFT...SW FLOW
AHEAD DOWNSTREAM OF A WEAK TROUGH WILL CONTINUE WARM/MOIST FLOW
ABOVE THE SURFACE WEDGE...WHILE SOME ENHANCED CONFLUENCE WILL
ACTUALLY HELP REINFORCE ITS STRENGTH. THE BIGGEST QUESTION MARK
TUESDAY REVOLVES AROUND WINTRY PRECIP POTENTIAL EARLY TUESDAY
MORNING. NAM/GFS SOUNDINGS ARE IN VERY GOOD AGREEMENT THAT SURFACE
TEMPS TUESDAY MORNING WILL BE BELOW FREEZING ACROSS MOST...IF NOT
ALL...OF THE CWA...WHILE TEMPS BETWEEN 950MB AND 850MB WARM TO +2C
TO +4C. MOIST LOW LEVELS OF THE COLUMN PERSIST ALL OF TUESDAY...BUT
VERY DRY AIR EXISTS ABOVE 850MB...SUCH THAT PWATS REMAIN RATHER
LOW...AROUND ONE-HALF INCH. SO THERE IS STILL CONSIDERABLE
UNCERTAINTY AS TO THE POTENTIAL FOR PRECIP...EVEN MORE DETERMINING
POSSIBILITY OF FREEZING RAIN. SOUNDINGS WOULD SUGGEST SOME LIGHT
FREEZING DRIZZLE CONTINUING SEVERAL HOURS INTO TUESDAY AS TEMPS ONLY
VERY SLOWLY WARM...LIKELY MUCH SLOWER THAN GUIDANCE DUE TO CLOUDS
AND REINFORCING WEDGE. STILL...WILL CARRY XL FOR ALL ZONES INTO
TUESDAY MORNING...LASTING MAYBE A BIT LONGER IN THE NORTH.
AGAIN...AM CONCERNED ABOUT LACK OF FORCING (ISENTROPIC LIFT IS VERY
WEAK) AND THE DRY AIR ALOFT...SO WILL KEEP QPF AT 0 FOR NOW. THIS IS
A VERY BORDERLINE SITUATION HOWEVER...SINCE SIMPLY A TRACE OF ZR
REQUIRES A WW.Y...SO WILL NEED TO MONITOR WHAT WILL LIKELY BE A
FLUID SITUATION OVERNIGHT INTO TUESDAY MORNING FOR POTENTIAL
EXPANSION OF CURRENT WW.Y TO INCLUDE MORE OF THE CWA.

A MORE IMPRESSIVE AREA OF PRECIP WILL BLOSSOM ACROSS THE AREA
TUESDAY NIGHT INTO WEDNESDAY...AS ISENTROPIC LIFT INCREASES
DRAMATICALLY OVERHEAD IN CONJUNCTION WITH AN AREA OF LOW PRESSURE
DEVELOPING OFFSHORE ALONG THE STALLED BOUNDARY. FORECAST PROFILES
SATURATE CONSIDERABLY...AND MOS P12/P24 VALUES SKYROCKET TO THE HIGH
LIKELY/LOW CATEGORICAL RANGE INTO WEDNESDAY. HOWEVER...THE NAM IS
QUITE A BIT DRIER THAN THE GFS ON WEDNESDAY...AND WILL NOT BE AS
AGGRESSIVE AS GFS IS SHOWING FOR QPF...BUT DEFINITELY BETTER RAIN
CHANCES TUESDAY NIGHT/WED THAN TUESDAY MORNING. FORTUNATELY...TEMPS
WILL HAVE WARMED ABOVE FREEZING BY TUESDAY NIGHT...SO JUST A COLD
RAIN IS EXPECTED.

ANOTHER BREAK IN PRECIP IS POSSIBLE AS ISENTROPIC LIFT WEAKENS LATE
WEDNESDAY...BUT RENEWED HEAVIER RAIN IS LIKELY LATE IN THE PERIOD
AND ON THURSDAY AS A SECOND AREA OF LOW PRESSURE DEVELOPS ALONG THE
BOUNDARY OFFSHORE. INHERITED POP SHOWS INCREASING TO HIGH-CHC FROM
SW TO NE TOWARDS THE END OF THE PERIOD...AND FEEL THIS IS WARRANTED
SO WILL MAKE ONLY MINIMAL INCREASE TO THE WED NIGHT PORTION OF THE
FORECAST.

TEMPS WILL BE WELL BELOW NORMAL ON TUESDAY AS THE REINFORCING WEDGE
COMBINED WITH CLOUD COVER AND PRECIP WILL PREVENT MUCH WARMING
THROUGH THE DAY. EXPECT HIGHS WILL PEAK ONLY IN THE 30S MUCH OF THE
AREA...BUT SOME LOW 40S POSSIBLE ALONG THE COAST. THIS IS 20 TO 30
DEGREES BELOW NORMAL FOR THE DATE! LITTLE VARIATION IN TEMPS FOR
MINS TUESDAY NIGHT WITH LOWS IN THE LOW/MID 30S ACROSS THE AREA.
SOME WARMING EXPECTED WEDNESDAY...BUT TEMPS WILL REMAIN WELL BELOW
NORMAL...RISING INTO THE MID/UPPR 40S...WITH LOWS WEDNESDAY NIGHT
DROPPING BACK INTO THE MID/UPPR 30S.
-- End Changed Discussion --

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
AS OF 300 PM MONDAY...A CLASSIC COASTAL LOW SHOULD BE TAKING
SHAPE OFF THE CAROLINA COAST THURSDAY...SPREADING PLENTY OF THICK
CLOUDS AND RAIN ACROSS THE AREA. WITH 12Z GFS WAS IN EXCELLENT
AGREEMENT WITH THE 00Z ECMWF REGARDING THE DEGREE OF ISENTROPIC
LIFT AND LOW-LEVEL TEMPERATURES EXPECTED DURING THE DAY. HIGHS
SHOULD ONLY REACH THE MID TO UPPER 40S. I HAVE RAISED POPS TO 80
PERCENT AND STORM-TOTAL QPF TO NEAR 1 INCH PENDING CONFIRMATION
FROM ANOTHER ROUND OR TWO OF MODEL RUNS.

THE STRONG UPPER LEVEL SYSTEM WILL ROLL ACROSS THE AREA EARLY FRIDAY
MORNING. PLENTY OF MOISTURE ALOFT AND PERIODS OF LIFT SHOULD ALLOW
RAIN TO CONTINUE...ESPECIALLY ALONG THE COAST INTO FRIDAY MORNING...
WITH DRYING CONDITIONS DEVELOPING FROM WEST TO EAST DURING THE DAY.
THE 12Z GFS LOOKED SIMILAR TO THE 00Z ECMWF...BUT THE 12Z ECMWF WAS
MUCH SLOWER WITH THE EASTWARD PROGRESSION OF THE UPPER LEVEL SYSTEM
AS IT BOMBS THE SURFACE LOW OFF THE NC COAST. ROUGHLY 20 PERCENT OF
THE 12Z GFS ENSEMBLE SOLUTIONS SHOWED A STRONG SURFACE LOW LIKE THE
12Z ECMWF SITTING OFF THE COAST FRIDAY...SO THIS IDEA WILL HAVE TO
BE WATCHED CLOSELY. ASSUMING WE GET SOME SUNSHINE BEHIND THE
DEPARTING UPPER TROUGH FRIDAY HIGHS SHOULD REACH 53-57...COOLEST AT
THE COAST. (OF COURSE IF THE 12Z ECMWF IS RIGHT AND WE STAY CLOUDY/
RAINY/WINDY MOST OF THE DAY THESE HIGHS COULD BE 10 DEGREES TOO
OPTIMISTIC)

SURFACE AND UPPER LEVEL RIDGING FINALLY BUILDS IN FRIDAY NIGHT AND
SATURDAY WITH MAINLY CLEAR SKIES AND RISING HEIGHTS AND THICKNESSES.
HIGHS IN THE 60S SATURDAY WILL SEEM WONDERFUL AFTER THURSDAY AND
FRIDAY. THE SURFACE HIGH SHOULD PUSH OFFSHORE SATURDAY AFTERNOON
WITH SOUTHWESTERLY SYNOPTIC WINDS PLUS THE DAYTIME SEABREEZE WORKING
TOGETHER TO KEEP THE BEACHES CONSIDERABLY COOLER COMPARED TO INLAND
LOCATIONS.

SUNDAY...SUBTROPICAL JET STREAM MOISTURE SHOULD INCREASE ALOFT WITH
CONSIDERABLE MID AND HIGH CLOUDS EXPECTED. THE 12Z GFS WAS MUCH
FARTHER EAST THAN EITHER OF TODAY`S ECMWF RUNS WITH AN UPPER LEVEL
SYSTEM CUTTING OFF IN THE DESERT SOUTHWEST SUNDAY. GOING WITH THE
ECMWF SOLUTION MEANS WE SHOULD HAVE LITTLE POTENTIAL FOR
PRECIPITATION EARLY NEXT WEEK...UNLESS A FEW SPRINKLES OR SHOWERS
DEVELOP ALONG A SOUTHWARD-MOVING BACKDOOR COLD FRONT SLIDING DOWN
THE EAST COAST SUNDAY EVENING. THIS BACKDOOR FRONT WILL BE THE
RESULT OF AN UPPER TROUGH MOVING OFF THE NEW ENGLAND COAST
SUNDAY...BUT SHOULD BRING LITTLE AIRMASS CHANGE SUNDAY NIGHT INTO
MONDAY.
-- End Changed Discussion --

&&

.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
AS OF 00Z...KCRE/KMYRKILM TERMINALS ARE CURRENTLY IFR WITH STRONG
N-NNE WINDS GUSTING TO 25-30 KTS. AT KFLO/KLBT FLIGHT CONDITIONS
HAD IMPROVED TO BORDERLINE MVFR. THERE IS STILL A POTENTIAL FOR
SLEET AND/OR FREEZING RAIN/DRIZZLE EARLY THIS EVENING MAINLY AT
KFLO/KLBT WITH MAINLY LIQUID SHOWERS MIXED WITH SOME SLEET AT THE
COASTAL TERMINALS. BUT OVERALL A DECREASING TREND FROM WEST TO EAST
IS INDICATED BY THE MODELS WITH PRECIPITATION ENDING AROUND 05Z AS
DRIER AIR MOVES INTO THE MID AND UPPER LEVELS. BASED ON LATEST
CEILING TRENDS HAVE INDICATED MVFR CIGS DEVELOPING SOUTH AS THE
WEDGE OF COLDER AIR DEEPENS. BUT UNTIL PRECIPITATION ENDS THERE WILL
BE THE THREAT FOR IFR CIGS/VSBYS AT ALL TERMINALS.

AS THE UPPER SYSTEM PASSES HAVE INDICATED PERIODS OF VFR BUT
CONFIDENCE IS LOW AND ANY VFR MAY BE SHORT-LIVED. MOSTLY MVFR
CONDITIONS EXPECTED THROUGH THE REMAINDER OF THE TAF VALID PERIOD
DUE TO COPIOUS AMOUNTS OF LOW-LEVEL MOISTURE. SOME MODELS ARE
SHOWING AN INCREASE IN LIGHT PRECIPITATION BY 18Z AT THE COASTAL
TERMINALS. ALTHOUGH THERE IS WEAK OVA CONFIDENCE OF ANY SIGNIFICANT
PRECIPITATION IS LOW DUE TO DRY AIR IN THE MID LEVELS.

EXTENDED OUTLOOK...MVFR/CHANCE SHOWERS THROUGH THE PERIOD. BEST
CHANCE PRECIPITATION/IFR WED AND THURS ENG THROUGH FRI. VFR SAT.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
NEAR TERM /THROUGH TONIGHT/...
AS OF 1100 PM MONDAY...BORDERLINE POST ARCTIC COLD FRONTAL N-NE GALE
FORCE WINDS WILL RULE THE OVERNIGHT PERIOD. GUSTS TO GALE FORCE
HAVE BEEN OCCASIONAL TO FREQUENT...ESPECIALLY JUST OUTSIDE THE
LOCAL WATERS IE. 41013 GUSTING OVER 40 KT THE PAST COUPLE HOURS.
THE GALE WARNING CRITERIA HAS BEEN SATISFIED FOR FOR THE
REMAINDER OF THE OVERNIGHT. THE TIGHTENING SFC PG AND THE ARCTIC
SURGE WILL CONTINUE OVERNIGHT...WITH THE SFC PG LOOSENING SOME
AFTER DAYBREAK TUESDAY. N-NNE WINDS SUSTAINED AT 20 TO 30
KT...WITH OCCASIONAL GALE FORCE GUSTS...WILL DOMINATE THE
OVERNIGHT PERIOD. SIGNIFICANT SEAS WILL RANGE BETWEEN 5 AND 8
FT...WITH THE HIGHER SEAS OF THIS RANGE OCCURRING ACROSS THE OUTER
WATERS OFF CAPE FEAR...AND THE OUTER WATERS OFF FROM THE MOUTH OF
WINYAH BAY. THE LOCALLY PRODUCED WIND DRIVEN WAVES AT AVERAGE AND
DOMINANT PERIODS OF 6 SECONDS...WILL DOMINATE THE SIGNIFICANT SEAS
OVERNIGHT INTO TUESDAY. AN UNDERLYING AND IDENTIFIABLE 9 TO 10
SECOND PERIOD 1 TO 3 FOOT SE GROUND SWELL...WILL CO-EXIST WITH
THIS BUILDING WIND WAVE.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 PM MONDAY...ARCTIC FRONT WILL BE OFFSHORE AT THE START
OF THE PERIOD...WITH A STRONG WEDGE OF HIGH PRESSURE BUILDING DOWN
ALONG THE COAST BEHIND IT. THIS WEDGE WILL CONTROL THE LOCAL WIND
TRAJECTORY THROUGH THE PERIOD...WITH A NE DIRECTION PERSISTENT
THROUGH MID-WEEK. SPEEDS WILL CHANGE WITH THE FLUCTUATING
GRADIENT...EASING FROM 15-25 KTS EARLY TUESDAY TO 10-15 KTS LATE
TUESDAY...BEFORE INCREASING AGAIN TO 15-20 KTS WEDNESDAY NIGHT.
SEAS WILL BE DRIVEN PRIMARILY BY A 6-7 NE WIND WAVE...WITH
AMPLITUDES FALLING FROM 4-7 FT EARLY...TO 3-5 FT MUCH OF THE
PERIOD...AND RISING AGAIN WEDNESDAY NIGHT TO 3-6 FT. A SMALL CRAFT
ADVISORY WILL LIKELY BE NEEDED FOR PORTIONS OF THE SHORT TERM.

LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 300 PM MONDAY...A CLASSIC COASTAL LOW WILL BE DEVELOPING
OFF THE SOUTHEAST U.S. COAST THURSDAY. VIRTUALLY ALL MODEL
GUIDANCE SHOWS MULTIPLE LOW PRESSURE CENTERS ALONG A LINE FROM
FLORIDA TO NORTH CAROLINA THURSDAY MORNING CONSOLIDATING INTO A
SINGLE LOW ABOUT 100 MILES OFF THE SOUTH CAROLINA COAST THURSDAY
EVENING. THE LOW SHOULD STEADILY DEEPEN AS IT FOLLOWS THE GULF
STREAM NORTHEASTWARD. AN EXTENDED PERIOD OF SMALL CRAFT ADVISORY
CONDITIONS ARE EXPECTED FOR NORTHEAST/NORTH WINDS AND SEAS.

MODELS DIVERGE IN HOW THEY HANDLE THE LOW FRIDAY: THE 12Z GFS AND
00Z ECMWF TAKE THE LOW OUT TO SEA WITH DIMINISHING IMPACTS FRIDAY
AFTERNOON AND EVENING. THE 12Z ECMWF IS MARKEDLY DIFFERENT
HOWEVER...SLOWING THE EASTWARD MOVEMENT OF LOW DOWN SIGNIFICANTLY ON
FRIDAY AS IT BOMBS THE STORM DOWN TO BELOW 1000 MB CENTRAL PRESSURE
WHILE OVER THE WARM WATER SOUTHEAST OF CAPE LOOKOUT. THIS SCENARIO
COULD BRING NEAR-GALE FORCE WINDS ACROSS THE CAROLINA COASTAL WATERS
FRIDAY PERSISTING INTO FRIDAY EVENING. IT APPEARS BY SATURDAY THE
LOW SHOULD BE WELL OFFSHORE WITH HIGH PRESSURE BUILDING OVER THE
AREA FROM THE WEST WITH MUCH LIGHTER WINDS AND QUICKLY DIMINISHING
SEAS.
-- End Changed Discussion --

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR SCZ017-023-
     024.

NC...WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR NCZ087-096-
     105-106.

MARINE...GALE WARNING UNTIL 6 AM EST TUESDAY FOR AMZ250-252-254-256.

&&

$$
SYNOPSIS...JDW
NEAR TERM...DCH
SHORT TERM...JDW
LONG TERM...TRA
AVIATION...MRR