217 
FXUS62 KILM 250824
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
324 AM EST TUE FEB 25 2014

.SYNOPSIS...
HIGH PRESSURE WILL DRIFT OFFSHORE TODAY. A COLD FRONT WILL MOVE
ACROSS THE AREA TONIGHT INTO WEDNESDAY BRINGING SOME SHOWERS TO
THE AREA. COLD HIGH PRESSURE WILL BRING WELL BELOW NORMAL
TEMPERATURES WEDNESDAY AND INTO THE WEEKEND. A SIGNIFICANT WARM-UP
IS POSSIBLE FOR EARLY NEXT WEEK...ALONG WITH INCREASING RAIN
CHANCES.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM TUESDAY...A RATHER COMPLEX 24 HOURS IS AHEAD OF US
WEATHERWISE. SURFACE HIGH PRESSURE IS MOVING OFF THE VIRGINIA
COAST THIS MORNING...WITH VEERING WINDS ALREADY OBSERVED OFFSHORE.
WARM FRONTOGENESIS IS OCCURRING ALONG THE WESTERN EDGE OF THE GULF
STREAM AS THE AIRMASS QUICKLY MODIFIES OVER WATER TEMPS IN THE MID
TO UPPER 70S. UP AT 300 MB THERE ARE TWO BRANCHES OF THE JET
DISCERNIBLE: THE POLAR JET LIES ACROSS THE CENTRAL APPALACHIANS
AND MID-ATLANTIC REGION...WHILE THE SUBTROPICAL JET COMES OUT OF
NORTHERN MEXICO AND CROSSES THE GULF COAST. CIRRUS CLOUDS COVERING
THE CAROLINAS EARLY THIS MORNING ARE DUE TO A WEAK DISTURBANCE IN
THE SUBTROPICAL JET OVER NORTHERN FLORIDA THAT SHOULD BE OFFSHORE
IN THE NEXT SIX HOURS.

A SECOND SUBTROPICAL JET DISTURBANCE WILL MOVE THROUGH THE SOUTHERN 
MS VALLEY THIS AFTERNOON. OUR OFFSHORE WARM FRONT WILL BE DRAWN 
INLAND TODAY BY SURFACE PRESSURE FALLS OCCURRING AHEAD OF THIS 
DISTURBANCE. WITH SEVERAL HOURS OF MOSTLY SUNNY SKIES EXPECTED EAST 
OF I-95 LATE THIS MORNING THIS SHOULD ALLOW TEMPERATURES TO RISE 
INTO THE 60S AND LOWER 70S BY EARLY AFTERNOON...WARMEST SOUTH OF 
FLORENCE AND CONWAY. DURING THE MID AND LATE AFTERNOON MOISTURE WILL 
INCREASE FROM THE WEST BETWEEN 850 AND 700 MB. COUPLED WITH MODEST 
ISENTROPIC LIFT ALONG THE 295K THETA SURFACE THIS COULD PRODUCE 
ISOLATED SHOWERS. POPS ARE LIMITED TO 20 PERCENT AND MAINLY FOR 
COASTAL LOCATIONS.

THIS EVENING THE BEST PRESSURE FALLS WILL SHIFT OFFSHORE AS A MUCH 
STRONGER POLAR JET DISTURBANCE APPROACHES FROM THE NORTHWEST. THIS 
WILL TAKE THE WARM FRONT ACROSS EAST-CENTRAL NORTH CAROLINA AND PUSH 
IT SOUTHWARD AS A COLD FRONT BEHIND A DEEPENING SURFACE LOW 
OFFSHORE...WITH COOLER AIR SURGING SOUTHWARD TO THE SANTEE RIVER 
OVERNIGHT. ISENTROPIC FIELDS INDICATE LITTLE POTENTIAL FOR 
PRECIPITATION DURING THE EVENING HOURS...HOWEVER INCREASING LIFT 
AGAIN ALONG THE 295K THETA SURFACE VERY LATE TONIGHT SHOULD PRODUCE 
AN AREA OF SHOWERS ACROSS SOUTH CAROLINA SPREADING TO THE NC/SC 
COAST BY DAYBREAK.

THE 00Z NAM MODEL APPEARS TO HAVE A BETTER HANDLE ON THE DEVELOPMENT 
AND MOVEMENT OF THE WARM FRONT TODAY AND THE OFFSHORE LOW TONIGHT. 
THE NAM'S MAX/MIN TEMPERATURES ALSO APPEAR BETTER THAN THE GFS... 
ALTHOUGH IT IS CURIOUS WHY BOTH THE NAM AND GFS MOS PRODUCTS ARE SO 
COOL WITH HIGHS TODAY GIVEN RAW MODELS RUNNING SEVERAL DEGREES 
WARMER. MY FORECAST HIGHS ARE WARMER THAN NAM OR GFS MOS... 
PARTICULARLY NEAR THE COAST.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 300 AM TUESDAY...COLD FRONT WILL BE DRAPED ALONG OR JUST SOUTH 
AND OFFSHORE OF THE CWA AT THE START OF THE PERIOD. MOST DIFFICULT 
PART OF THE FORECAST WILL BE HOW THE INTERACTION OF THIS BOUNDARY 
AND SOME ENHANCED MOISTURE RETURN WILL AFFECT THE CWA WITH RAINFALL 
ON WEDNESDAY. THE COLD FRONT WILL MOVE ONLY VERY SLOWLY SOUTHWARD AS 
THE REGION REMAINS BENEATH THE BASE OF THE EASTERN TROUGH...THUS 
FLOW BECOMES NEARLY BOUNDARY-PARALLEL ON WEDNESDAY. AS THIS FRONT 
STALLS NEAR THE AREA...MOISTURE INCREASES ALONG IT...AND SOME WEAK 
LIFT DUE TO MID-LEVEL IMPULSES WILL TRY TO SPAWN SOME POST-FRONTAL 
RAINFALL ACROSS THE CWA. NAM/GFS ARE WETTER AND IN BETTER AGREEMENT 
THAN THE ECMWF...SO WILL LEAN MORE ON THESE MODELS FOR PRECIP 
POTENTIAL ON WEDNESDAY. THE BEST CHANCES FOR PRECIP WILL BE ALONG 
THE SE THIRD OF THE CWA...CLOSEST TO THE BOUNDARY AND WHERE 
ISENTROPIC LIFT FROM 290-300K IS FOCUSED...BUT SREF PROBS SUGGEST AT 
LEAST 60% 12-HR CHANCE OF 0.01 QPF ACROSS THE ENTIRE CWA. INHERITED 
POP HAS LIKELY ACROSS THE EAST WITH HIGH-CHC WEST...AND WILL BUMP 
THESE NUMBERS BUT KEEP WITHIN THE SAME CATEGORIES FOR WEDNESDAY. 
HIGHEST CHANCES WILL BE WED MORNING INTO THE AFTN...DROPPING FROM NW 
TO SE THROUGH THE EVE AS THE FRONT DRIFTS SLOWLY AWAY AND THE 
MID-LEVEL IMPULSE PUSHES EASTWARD. 

WHILE THE WEAK CAA...CLOUDS...AND RAIN WILL KEEP TEMPS WEDNESDAY 
WELL BELOW NORMAL...AROUND 50 FOR HIGHS...SKY CONDITIONS WILL CLEAR 
RAPIDLY WED NIGHT. AT THE SAME TIME...HIGH PRESSURE FROM THE WEST 
WILL CONTINUE TO RIDGE TOWARDS THE AREA. A RELATIVELY WEAK PRESSURE 
GRADIENT WED NIGHT WILL LEAVE ONLY LIGHT NORTH WINDS AHEAD OF THIS 
HIGH PRESSURE...WHICH COMBINED WITH CLEARING SKY CONDITIONS WILL 
CREATE A COLD NIGHT INTO THU MORNING...AND EXPECT NEARLY THE ENTIRE 
AREA TO FALL BELOW FREEZING...WITH MID 20S POSSIBLE IN THE TYPICALLY 
COLDER SPOTS.

SUBTLE AIR MASS MODIFICATION OCCURS THURSDAY THANKS TO SURFACE HIGH 
PRESSURE RIDGE AXIS BULGING UP TOWARDS THE MID-ATLANTIC. THIS WILL 
BE SOMEWHAT OFFSET BY CONTINUED LOW THICKNESSES SOUTH OF THE COLD 5H 
VORTEX ACROSS NEW ENGLAND...AND THUS WHILE THURSDAY WILL BE WARMER 
THAN WEDNESDAY...TEMPS WILL STAY BELOW NORMAL...RISING ONLY INTO THE 
MID 50S...WITH A FEW UPPER 50S POSSIBLE NEAR THE SOUTH SANTEE RIVER. 
A RENEWED SURGE OF COLD AIR IS NOW PROGGED FOR THURSDAY NIGHT AS A 
SECONDARY DRY COLD FRONT CROSSES AHEAD OF ARCTIC HIGH PRESSURE 
DROPPING OUT OF CANADA. THIS WILL CREATE A COLD AND BREEZY NIGHT 
THURSDAY NIGHT...AS LOW DROP ONCE AGAIN TO FREEZING OR BELOW...WITH 
EVEN COLDER APPARENT TEMPS.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 300 AM TUESDAY...COLD TO START THE EXTENDED AS ARCTIC HIGH 
PRESSURE DEVELOPS INTO A WEDGE ALONG THE EAST COAST. THIS WILL 
CREATE COOL NE WINDS INTO THE FIRST HALF OF THE WKND...WITH TEMPS 
REMAINING SOLIDLY BELOW CLIMO FOR THE END OF FEBRUARY. WHILE 
GUIDANCE HAS BEEN ADVERTISING A SOUTHERN STREAM LOW FOR SEVERAL DAYS 
NOW...THIS FEATURE HAS BECOME LESS INTENSE...AND NOW THE SURFACE 
REFLECTION HAS BASICALLY DISAPPEARED THANKS TO WEAKER MID-LEVEL 
FORCING AND BAROCLINIC INSTABILITY. STILL...THERE IS AT LEAST DECENT 
POTENTIAL FOR SOME SHOWERS ON SATURDAY BENEATH THE MID-LEVEL 
IMPULSE...BUT OVERALL QPF LOOKS LIMITED. ADDITIONALLY...WITH THE 
COOL AIR IN PLACE WITHIN THE WEDGE...THIS OVERRUNNING SCENARIO MAY 
PROMOTE A MIXED P-TYPE EVENT...ESPECIALLY WELL INLAND. TEMPS WILL BE 
MARGINAL AT-BEST FOR ANYTHING OTHER THAN THAT LIQUID...AND WILL KEEP 
-RW AS WX TYPE FOR NOW...BUT THERE IS AT LEAST A SMALL CHANCE FOR 
SOME FROZEN PRECIP FRIDAY NIGHT/SAT AM.

GUIDANCE DIFFERS CONSIDERABLY INTO THE BEGINNING OF NEXT WEEK. GFS 
BREAKS DOWN THE WEDGE QUICKLY AS MID-LEVEL RIDGING 
DEVELOPS...CENTERED OFF THE FLORIDA COAST. ECMWF SHOWS A SIMILAR 
PROCESS BUT WITH A SLOWER TEMPORAL EVOLUTION. THIS CAUSES 15+ DEGREE 
TEMP DIFFERENCES IN THE FORECASTS FOR NEXT WEEK. A QUICK GLANCE AT 
SOME OF THE ENSEMBLES SUGGESTS THAT THE OP-GFS IS WELL TOO WARM AS 
IT IS ON THE HIGH SIDE OF ALL ITS ENSEMBLE THICKNESSES. STILL...THE 
UPPER PATTERN FAVORS WEDGE BREAKDOWN AND AT LEAST A MARGINAL WARMUP 
SUN/MON...SO WILL BUMP TEMPS TOWARDS AND ABOVE CLIMO FOR EARLY NEXT 
WEEK. A MORE IMPRESSIVE LOW PRESSURE SYSTEM MAY APPROACH 
MONDAY...AND WILL KEEP INHERITED CHC POP ATTM.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
AS OF 06Z...THICKENING CIRRUS IS INHIBITING RADIATIONAL COOLING 
EARLY THIS MORNING...AND THE RATE OF TEMPERATURE DECREASE IS SMALL 
AS A RESULT. A VERY THIN LAYER OF MOISTURE NEAR THE SURFACE WITH 
DEWPOINTS IN THE UPPER 30S AND LOWER 40S IS PRODUCING OCCASIONAL 
MVFR VISIBILITIES AT KCRE AND KILM. AS DRIER AIR FILTERS IN FROM THE 
NORTH OVER THE NEXT 3-4 HOURS THIS SHOULD IMPROVE VISIBILITIES 
BEFORE DAYBREAK. OTHERWISE SURFACE HIGH PRESSURE OFF THE VIRGINIA 
COAST WILL MOVE FARTHER OFFSHORE THIS MORNING...WITH SURFACE WINDS 
VEERING FROM NORTHEAST TO EAST AFTER DAYBREAK. SPEEDS SHOULD REMAIN 
RATHER LIGHT REGARDLESS.

RAIN CHANCES MAY INCREASE ALONG THE COAST IN THE LATE AFTERNOON 
HOURS...INFILTRATING INLAND INTO THE EVENING HOURS AND CONTINUING 
THROUGH THE TAF PERIOD. COULD SEE LOW CIGS CREATE MVFR 
CONDITIONS...BUT GIVEN LOWERED CONFIDENCE HAVE NOT INTRODUCED ATTM.

EXTENDED OUTLOOK...MVFR CIGS AND RAIN EXPECTED INTO WEDNESDAY. VFR 
THURSDAY. MVFR CIGS COULD DEVELOP AGAIN LATE FRIDAY INTO SATURDAY 
ALONG WITH ANOTHER CHANCE OF RAIN.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 300 AM TUESDAY...SEASONS WILL CHANGE AT LEAST TWICE ACROSS
THE COASTAL WATERS TODAY AS A FRONT WAVERS ACROSS THE AREA. A WARM
FRONT DEVELOPING ALONG THE WESTERN EDGE OF THE GULF STREAM SHOULD
PUSH INLAND LATER THIS MORNING...WITH NORTHEAST WINDS VEERING TO
THE SOUTH. WINDS SPEEDS WILL INCREASE TO 10-15 KNOTS AS DIRECTIONS
CONTINUE TO VEER SOUTHWESTERLY DURING THE AFTERNOON. THIS VEERING
SHOULD BE IN RESPONSE TO FALLING PRESSURES AS LOW PRESSURE
DEVELOPS ALONG THE COAST TODAY...THEN OFFSHORE THIS EVENING.
CLOCKWISE WINDS BLOWING AROUND THIS LOW SHOULD PUSH THE WARM FRONT
BACK SOUTHWARD AS A COLD FRONT THIS EVENING. THE FRONT MAY PRESS
ALL THE WAY TO THE SANTEE RIVER...WITH NORTH TO NORTHEAST WINDS
STRONGEST ACROSS THE NC WATERS CLOSEST TO THE POSITION OF THE LOW.

SEAS CURRENTLY RANGE FROM 2-3 FEET WITH DOMINANT PERIODS AROUND 9 
SECONDS IN SOUTHEAST SWELL. A SMALL SHORT PERIOD CHOP WILL DEVELOP 
IN THE SOUTH-SOUTHWEST WIND BEHIND THE WARM FRONT...WITH CONFUSED 
SEAS FOR A PERIOD THIS EVENING AS WINDS SHIFT TO THE NORTH AS THE 
FRONT IS PUSHED ACROSS AGAIN. TOTAL SEA HEIGHTS WILL PROBABLY NOT 
EXCEED 4 FEET AT ANY POINT THROUGH TONIGHT.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... 
 AS OF 300 AM TUESDAY...COLD FRONT MOVING OFFSHORE AT THE START OF 
THE PERIOD WILL DRIFT SOUTH OF THE AREA INTO THURSDAY...WITH 
NORTHERLY WINDS INCREASING TO 15-20 KTS...AND REMAINING AT THESE 
SPEEDS INTO THURSDAY MORNING. THESE WINDS WILL EASE AND BACK TO THE 
SW ON THURSDAY AS A RIDGE OF HIGH PRESSURE BRIEFLY ENVELOPS THE 
AREA...BUT WILL QUICKLY RETURN TO THE NORTH AT 15-20 KTS AT THE END 
OF THE PERIOD AS A SECOND COLD SURGE MOVES ACROSS THE WATERS. EVEN 
THOUGH WINDS WILL BE GUSTY ON WEDNESDAY...THE NORTHERLY COMPONENT 
WILL INHIBIT SUBSTANTIAL WAVE GROWTH...AND THUS SEAS WILL RISE TO 
PEAK AT 3-5 FT WEDNESDAY EVE...BEFORE FALLING BACK TO 1-3 FT DURING 
THURSDAY. RENEWED AMPLIFICATION IS EXPECTED AT THE END OF THE SHORT 
TERM AS THE WINDS ONCE AGAIN RISE FROM THE NORTH...WITH WAVE HEIGHTS 
BECOMING 2-4 FT BY FRIDAY MORNING.

LONG TERM /FRIDAY THROUGH SATURDAY/...
AS OF 300 AM TUESDAY...DEVELOPING WEDGE OF HIGH PRESSURE EXTENDING 
DOWN THE EAST COAST WILL CREATE A PROLONGED PERIOD OF NE WINDS OVER 
THE COASTAL WATERS...AND CAUTIONARY STATEMENTS MAY BE REQUIRED ON 
FRIDAY. STRENGTHENING WEDGE FRIDAY FORCES A PINCHED PRESSURE 
GRADIENT...AND NE WINDS RISE TO AROUND 20 KTS ALL OF 
FRIDAY...DRIVING SEAS UP TO 4-5 FT...EXCEPT SW OF BRUNSWICK COUNTY 
WHERE THE WAVE SHADOW REGION WILL PERMIT ONLY MUCH SMALLER WAVE 
HEIGHTS. GRADIENT WILL EASE AT LEAST MARGINALLY ON 
SATURDAY...ALLOWING NE WINDS TO FALL TO 10-15 KTS...WITH SEAS 
FOLLOWING TO 2-4 FT.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...JDW
NEAR TERM...TRA
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...TRA
MARINE...TRA/JDW