Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 240308
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1008 PM EST SUN NOV 23 2014

.SYNOPSIS...
MILD TEMPERATURES WITH UNSETTLED WEATHER IS EXPECTED TONIGHT INTO
MONDAY AS A WARM FRONT CROSSES THE AREA.  A COLD FRONT WILL CROSS
THE COAST MONDAY NIGHT AND STALL OFFSHORE TUESDAY. COOL AND WET
CONDITIONS ARE EXPECTED WEDNESDAY...AS DEEPENING LOW PRESSURE MOVES
NORTH ALONG THE STALLED FRONT AND SKIRTS THE COAST. SKIES WILL
CLEAR OUT ON THANKSGIVING...WITH TEMPERATURES RUNNING SEVERAL
DEGREES BELOW NORMAL INTO THE COMING WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AS OF 1000 PM SUNDAY...TWO CONVECTIVE BANDS ARE CROSSING THE AREA
CURRENTLY AND SHOULD DROP A GENERAL 0.4 TO 0.5 INCHES OF RAIN WITH
EMBEDDED HEAVIER AMOUNTS. AT THE SURFACE THE WARM FRONT APPEARS TO
BE THROUGH FLORENCE AND IS APPROACHING MYRTLE BEACH. LATEST HIGH-RES
MODELING INDICATES THE BOUNDARY SHOULD MOVE OR JUMP NORTHWARD VERY
QUICKLY WITH ALL OF OUR FORECAST AREA WITHIN THE WARM SECTOR BY
MIDNIGHT.

CONCERNING SEVERE WEATHER POTENTIAL...INSTABILITY REMAINS THE
LIMITING FACTOR. IN ORDER FOR CONVECTION TO BECOME SURFACE-BASED
ANALYSIS OF THE 03Z SOUNDINGS FROM THE 23Z RUC INDICATES WE NEED A
SURFACE TEMP/DEWPOINT OF 69 DEGREES F...EQUIVALENT TO A SURFACE
THETA-E VALUE OF 333K. ANYTHING LESS THAN THIS SHIFTS THE CONVECTIVE
ORIGIN POINT UPWARD OFF THE SURFACE WITH A CORRESPONDING REDUCTION
IN SEVERE WEATHER RISK. 02/03Z SURFACE OBS INDICATE WE DO NOT HAVE
REQUISITE THETA-E VALUES IN PLACE AT THE SURFACE TO SUPPORT
SURFACE-BASED CONVECTION...AND THEREFORE ALL OF THE CURRENT ACTIVITY
LIKELY REMAINS ELEVATED. THE DRY SLOT IS APPROACHING FROM THE WEST
AND SHOULD SPELL AN END TO THE SOLID PRECIPITATION SHIELD OVER THE
NEXT FEW HOURS...WITH ONLY SCATTERED SHOWERS CONTINUING LATE TONIGHT
INTO MONDAY MORNING. PREVIOUS DISCUSSION FROM 645 PM FOLLOWS...

A WAVE OF HEAVY SHOWERS AND EMBEDDED THUNDERSTORMS ACROSS EASTERN
GEORGIA AND NOW CROSSING THE SANTEE RIVER INTO SOUTH CAROLINA WILL
MOVE ACROSS THE EASTERN CAROLINAS SHORTLY. RAINFALL EARLIER TODAY
WAS MAINLY DUE TO ISENTROPIC UPGLIDE AS MOIST WARM ADVECTION WITHIN
THE 850-700 MB LAYER PRODUCED GENTLE UNIFORM LIFT. THE BATCH OF
PRECIPITATION TO BEGIN SHORTLY IS BEING FORCED BY EXCELLENT UPPER
DIVERGENCE WITHIN THE RIGHT-ENTRANCE REGION OF A 250 MB JET STREAK
MOVING NORTH THROUGH WESTERN NC/VA THIS EVENING.

A WARM FRONT CURRENTLY EXTENDING FROM NEAR BEAUFORT SC WESTWARD
ACROSS AUGUSTA GA WILL MOVE NORTHWARD AT A GOOD CLIP OVER THE NEXT
FEW HOURS...BRINGING A NEARLY TROPICAL AIRMASS NORTHWARD ACROSS THE
AREA. MODEST SURFACE BASED INSTABILITY ON THE ORDER OF 300-600 J/KG
SHOULD DEVELOP ACROSS AREAS WHERE TEMP/DEWPOINTS ARE ABLE TO REACH
70 DEGREES F. WHEN COMBINED WITH 0-1 KM HELICITY VALUES OF 400-600
M^2/S^2 THE POTENTIAL EXISTS FOR SOME OF THESE CELLS TO ROTATE. I
FEEL THE OVERALL SEVERE WEATHER RISK REMAINS LOW SINCE SURFACE-BASED
INSTABILITY SHOULD NOT DEVELOP UNTIL THE WARM FRONT ARRIVES AND
WINDS BELOW 925 MB VEER MORE SOUTHWESTERLY. THIS WILL MAKE THE
VERTICAL WIND PROFILE UNIDIRECTIONAL REDUCING THE POTENTIAL FOR
TORNADIC STORMS. IF TEMPS/DEWPOINTS REMAIN BELOW 70 F MODEL FORECAST
SOUNDINGS INDICATE THE BOUNDARY LAYER WOULD BE STABLE WITH
CONVECTION REMAINING ELEVATED AND THEREFORE INHERENTLY LESS
DANGEROUS. WE WILL MONITOR RADAR CLOSELY THROUGH THE EVENING
WATCHING FOR ANYTHING THAT MIGHT WARRANT A STATEMENT OR SEVERE
WEATHER WARNING.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 4 PM SUNDAY...ODDLY MILD CONDITIONS TO ENGULF THE EASTERN
CAROLINAS MONDAY WITH STRONG WARM AIR ADVECTION PATTERN IN PLACE
AND A COLD FRONT AND UPPER TROUGH WEST OF THE FORECAST AREA. 65-70
TEMPERATURE RANGE TO GREET MOST AREAS DAYBREAK MONDAY...AS MAXIMUM
TEMPERATURES CLIMB INTO THE MIDDLE AND UPPER 70S...LIKELY UNDER A
CANOPY OF CLOUDS DUE TO EXTENT OF UPSTREAM CONVECTION. THE LOW-LVL
WIND FIELD REMAINS STRONG MONDAY...AND ANY SURFACE HEATING MONDAY
AFTERNOON COULD LEAD TO CONVECTION CAPABLE OF DAMAGING WIND...AND
EVEN SHOWERS WILL BRING LOCALLY STRONGER GUSTS. SPC MAINTAIN A LOW
END RISK NEAR THE COAST AHEAD OF A COLD FRONT.

TUESDAY A POST-FRONTAL DAY WHERE WEATHER HAZARDS WANE. THE UPSTREAM
TROUGH ALIGN HOWEVER WILL SUPPORT MORE IMPULSES RISING OUT OF THE
GULF. CYCLOGENESIS OFFSHORE OF NORTHERN FLORIDA OCCUR VERY LATE IN
THE PERIOD AND BECOME A WEATHER PLAYER BEYOND DAYBREAK WEDNESDAY AND
POP VALUES DO GRADUALLY RAMP UP TO THIS FEATURE LATE TUESDAY.

RECORD HIGH TEMPS MONDAY ARE ILM 79...FLO 83...CRE 76...LBT 78.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 4 PM SUNDAY...MAIN FOCUS FOR THE PERIOD REMAINS LOW PRESSURE
PASSING JUST OFF THE COAST WED. SHORTWAVE CROSSING THE WESTERN GULF
LATE TUE WILL ENHANCE SURFACE WAVE JUST OFF THE FL GULF COAST WED
MORNING. THIS LOW WILL TRAVEL NORTHEAST ALONG A STALLED BOUNDARY WED
INTO WED NIGHT WITH DEEP MOISTURE SPREADING OVER THE CAROLINAS. LOW
WILL REMAIN EAST OF THE COASTAL WATERS WITH INCREASING NORTHERLY
FLOW...CLOUD COVER...AND PERIODS OF HEAVY RAIN KEEPING TEMPERATURES
IN THE 40S FOR MUCH OF THE AREA. PRESENCE OF DEEP MOISTURE AND
STRONG LIFT/DIVERGENCE ALOFT WILL ENSURE PLENTY OF RAIN FALLS ACROSS
THE AREA WED. MID LEVEL TROUGH MOVES INTO THE AREA WED EVENING WITH
SIGNIFICANT AMOUNT OF DRY AIR MOVING IN...ENDING THE RAIN THREAT.

SUBTLE MID LEVEL TROUGHING IN THE WAKE OF THE EXITING SYSTEM REMAINS
OVER THE SOUTHEAST FRI...PUSHING A DRY COLD FRONT ACROSS THE AREA.
MID LEVEL PATTERN FLATTENS OUT FOR THE WEEKEND AND FLOW ALOFT
BECOMES PROGRESSIVE. HIGH PRESSURE BUILDING IN FOR THE WEEKEND
QUICKLY SHIFTS OFFSHORE WITH RETURN FLOW DEVELOPING AND TEMPS
CLIMBING BACK CLOSE TO CLIMO.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 00Z...A MIXTURE OF MVFR/IFR/POSSIBLE LIFR EXPECT TONIGHT AND
THROUGH THE OVERNIGHT HOURS AS UNSETTLED WEATHER ALLOWS FOR
SHRA/TSRA TO CREATE PERIODS OF HEAVY RAIN AND WIND...ALONG WITH LOW
CIGS AND FOG...TO AFFECT THE AREA. RAIN TAPERS OFF INTO THE EARLY
MORNING HOURS...THOUGH AREAS OF LOW CIGS AND FOG ARE ANTICIPATED
THROUGH THE PERIOD...WITH IMPROVEMENT TO VFR POSSIBLE INLAND DURING
THE AFTERNOON HOURS ON MONDAY.

LATEST RADAR IMAGERY DEPICTS LIGHT -SHRA MOVING ACROSS THE AREA THIS
EVENING WHILE OBS ARE REPORTING LOW CIGS AND AREAS OF FOG CREATING
MVFR/IFR AT ALL TAF SITES. WHILE ACTIVITY IS LIGHT NOW...SHOWERS AND
THUNDERSTORMS ARE POSSIBLE LATER TONIGHT INTO THE EARLY OVERNIGHT
HOURS...WITH ISOLATED SEVERE STORMS POSSIBLE. WITH ANY STRONGER
STORM COULD SEE HEAVY RAINFALL. AS FOR WINDS EXPECT SOUTHEASTERLY
AROUND 10 KTS WITH GUSTS UP TO 20 KTS...AND HIGHER GUSTS POSSIBLE IN
ANY TSRA. LATE OVERNIGHT...ANY SHRA/TSRA WILL TAPER OFF...BUT WILL
CONTINUING TO SEE DETERIORATED CONDITIONS AS LOW CIGS AND FOG
PERSISTS. WHILE LIFR CANNOT BE RULE OUT...OVERALL ANTICIPATE
MVFR/IFR. INTO MONDAY...WITH GUSTY SOUTHWEST WINDS...LOW CIGS WITH
AREAS OF FOG WILL PERSIST...THUS EXPECT MVFR/IFR. COULD SEE
IMPROVEMENT TO VFR IN THE AFTERNOON HOURS IN SPOTS...BUT TOWARDS THE
END OF THE PERIOD CONDITIONS WILL DETERIORATE BACK TO MVFR/IFR.

EXTENDED OUTLOOK...UNSETTLED WEATHER IS EXPECTED MONDAY AFTERNOON
THROUGH WEDNESDAY NEAR THE COAST...WITH OCCASIONAL SHOWERS AND
MVFR/IFR CONDITIONS. BECOMING VFR WEDNESDAY NIGHT...THROUGH FRIDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 PM SUNDAY...THE WARM FRONT APPEARS TO BE APPROACHING THE
MYRTLE BEACH VICINITY AS WINDS HAVE SHIFTED IN GEORGETOWN BUT
SOUTHEAST WINDS CONTINUE IN MYRTLE BEACH AND POINTS NORTHWARD ALONG
THE COAST. GUSTS OUT AT THE FRYING PAN SHOALS BUOY REMAIN ABOVE
GALE-FORCE...AND WINDS AT THE BEACHES NORTH OF CAPE FEAR ARE
APPROACHING GALE FORCE WITH 33 KNOTS RECENTLY REPORTED ON TOPSAIL
ISLAND (MESONET) AND 30 KNOTS AT MERCER PIER ON WRIGHTSVILLE BEACH.
SEAS ARE ALMOST FULLY DEVELOPED FOR THIS FETCH AND SPEED...13 FEET
OUT AT FRYING PAN SHOALS...10 FEET AT THE HARBOR BUOY SOUTH OF BALD
HEAD ISLAND...AND 9 FEET AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY.
NO SIGNIFICANT CHANGES ARE NEEDED FOR THIS LATE-EVENING UPDATE.
PREVIOUS DISCUSSION FROM 645 PM FOLLOWS...

THE WARM FRONT HAS MOVED THROUGH SAVANNAH AND IS RACING UP THE COAST
AT A PRETTY GOOD CLIP. MOST RECENT MODELS ARE TOO FAST WITH THE
FRONTAL TIMING...BUT AMONG THOSE THAT SEEM TO HAVE A GOOD HANDLE
(21Z HRRR, 22Z RUC, 12Z ECMWF) THE LATEST THINKING IS FOR FRONT TO
CROSS THE SANTEE RIVER 8-9 PM...CAPE FEAR AROUND 11 PM...AND TO BE
NORTH OF TOPSAIL ISLAND BY MIDNIGHT. THE FRONT WILL BE HERALDED BY A
SHIFT FROM SOUTHEAST TO SOUTH WINDS. ANOTHER HEAVY WAVE OF SHOWERS
AND EMBEDDED THUNDERSTORMS IN EASTERN GEORGIA AND NOW CROSSING THE
SAVANNAH RIVER INTO SOUTH CAROLINA SHOULD ARRIVE IN THE NEXT COUPLE
OF HOURS. HEAVY RAINFALL AND LIGHTNING ARE THE LARGEST THREATS.

WINDS HAVE BEEN GUSTING OVER GALE FORCE AT THE FRYING PAN SHOALS
BUOY FOR THE PAST THREE HOURS. BUOY 41004 EAST OF CHARLESTON IS IN
THE SAME ENVIRONMENT AND HAS ALSO GUSTED OVER GALE FORCE EARLY THIS
EVENING. CLOSER TO SHORE THE COLDER OCEAN WATER TEMPERATURE ON THE
SHALLOW CONTINENTAL SHELF IS INDUCED A MUCH MORE STABLE ATMOSPHERIC
BOUNDARY LAYER WITH LESS WIND ABLE TO MIX DOWN FROM ALOFT. DESPITE
WINDS JUST 1000 FEET ABOVE THE SURFACE EXPECTED TO REACH 50 KNOTS
IN JUST A COUPLE HOURS...WIND SPEEDS DOWN AT THE OCEAN SURFACE
SHOULD REMAIN 20-30 KNOTS ACROSS THE SC WATERS...AND 25-35 KNOTS
ACROSS THE NC WATERS WITH A HIGHER GUSTS WELL AWAY FROM SHORE WHERE
WATER TEMPERATURES ARE STILL IN THE RELATIVELY MILD MID 60S.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 4 PM SUNDAY...MONDAY MARINE CONDITIONS REMAIN DANGEROUS WITH
SEAS OF 5-9 FEET LIKELY AND HIGHEST AWAY FROM SHORE AND NEAR THE
FRYING PAN SHOALS. 20-30 KT SSW WINDS MONDAY...BECOMING WEST LATE
TUESDAY NIGHT OR EARLY MONDAY AS A SURFACE COLD FRONT MOVES ACROSS
THE WATERS. STRONG TSTMS REMAIN POSSIBLE MONDAY THROUGH TUESDAY
MORNING ON THE 0-20 NM WATERS. LARGE SSW-SE WAVES WILL MAKE UP THE
SEA SPECTRUM IN MIXED WAVE PERIODS OF 5-6 SECONDS AND 8-9 SECONDS.
IMPROVING CONDITIONS TUESDAY ALTHOUGH WAVE RECOVERY WILL STILL BE
UNDERWAY EARLY TUESDAY.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 4 PM SUNDAY...PERIOD OF HEADLINES SEEMS LIKELY WED INTO
WED NIGHT AS DEEPENING LOW PRESSURE PASSES JUST EAST OF THE
WATERS. WINDS WILL BACK FROM NORTH-NORTHEAST TO WEST WED INTO WED
NIGHT AS THE LOW LIFTS NORTHEAST. SPEEDS WILL PEAK IN THE 20 TO 25
KT RANGE WITH SEAS NEAR 20 NM FLIRTING WITH 6 TO 7 FT. OFFSHORE
FLOW WEAKENS LATE WED NIGHT INTO THU AS SURFACE HIGH TO THE WEST
BUILDS EAST. SPEEDS REMAIN CLOSE TO 15 KT THU WITH A SLIGHT
INCREASE FRI AS DRY COLD FRONT PASSES AND BRIEF COLD ADVECTION
DEVELOPS. AN OFFSHORE COMPONENT WILL KEEP SEAS WITHIN 20 NM IN THE
2 TO 4 FT RANGE THU AND FRI.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR AMZ254-256.

     SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM EST TUESDAY
     FOR AMZ250-252.

     GALE WARNING UNTIL MIDNIGHT EST TONIGHT FOR AMZ250-252.

&&

$$

SYNOPSIS...MJC/TRA
NEAR TERM...TRA
SHORT TERM...MJC
LONG TERM...III
AVIATION...SGL




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