Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 210545
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
140 AM EDT THU MAY 21 2015

.SYNOPSIS...
DEVELOPING LOW PRESSURE WILL SWEEP ACROSS NORTH CAROLINA ON
THURSDAY PUSHING A COLD FRONT OFFSHORE BY THURSDAY EVENING. HIGH
PRESSURE WILL BUILD IN FROM THE NORTH FRIDAY...BRINGING DRIER AIR
INTO THE REGION OVER THE WEEKEND. THE HIGH WILL MOVE OFFSHORE
SUNDAY INTO MONDAY BRINGING A RETURN OF HUMIDITY BY THE MIDDLE OF
NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
AS OF 1030 PM WEDNESDAY...IN THE WAKE OF THE SEA BREEZE...WHICH
TRAVELED ACROSS THE ENTIRE ILM CWA B4 DISSIPATING...A SHALLOW SFC
BASED STABLE MARINE LAYER CONTINUES TO EXIST FOR THE REMAINDER OF
THIS EVENING...WITH SOME MODIFICATIONS TO THIS LAYER OVERNIGHT.
LATEST CONVECTION ACROSS THE FA CONTINUES TO FALL APART DUE TO THE
MARINE INFLUENCE. WILL ONLY CARRY 20 POPS AT MOST FOR THE
REMAINDER OF THIS EVENING...MAINLY FOR POSSIBLE CONVECTION THAT
MAY AFFECT THE SOUTHERN 1 TO 2 THIRDS OF THE ILM CWA. FOR THE PRE-
DAWN THU HOURS...LOOKS LIKE ENOUGH SUBSIDENCE ALOFT TO EXIST
ACROSS THE FA BETWEEN THE EXITING MID-LEVEL S/W TROF TO THE EAST
AND THE APPROACHING MID-LEVEL S/W TROF FROM THE WEST.
HOWEVER...WITH A STALLED/MEANDERING FRONTAL BOUNDARY IN THE
VICINITY OR ACROSS THE FA...WILL STILL CARRY A LOW CHANCE POP.
WILL INCLUDE OVERNIGHT PATCHY FOG MAINLY ACROSS LOCATIONS THAT
RECEIVED OR WILL RECEIVE RAINFALL.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...BY MID-MAY STANDARDS A PRETTY DYNAMIC
SYSTEM WILL MOVE THROUGH NORTH CAROLINA THURSDAY. SURFACE LOW
PRESSURE NEAR CHARLOTTE AT SUNRISE WILL MOVE EAST-NORTHEASTWARD
TO THE OUTER BANKS BY EARLY EVENING. THIS LOW WILL BE SUPPORTED BY
A SW-NE ALIGNED 300 MB JET STREAK ALONG THE MID- ATLANTIC COAST.

0-6 KM BULK SHEAR WILL INCREASE TO 20-25 KT ACROSS SC TO 30-40 KT
ACROSS NC. 0-1 KM HELICITY WILL ALSO INCREASE AS YOU MOVE
NORTHWARD...AIDED BY LOCALIZED BACKING OF THE LOW-LEVEL FLOW IN
PROXIMITY TO THE SURFACE LOW. WHILE IT APPEARS THE BEST
JUXTAPOSITION OF SHEAR...INSTABILITY AND LOW-LEVEL CONVERGENCE WILL
OCCUR ALONG THE PATH OF THE SURFACE LOW JUST NORTH OF LUMBERTON...
ELIZABETHTOWN AND WILMINGTON...UNDOUBTEDLY THERE WILL BE SCATTERED
THUNDERSTORMS DEVELOPING SOUTH OF THE LOW WHERE CAPE AS HIGH AS
2000 J/KG COULD DEVELOP DURING THE DAY. MY FORECAST POPS THURSDAY
RANGE FROM 40-50 PERCENT FROM LBT EAST TO BURGAW...WITH LOWER POPS
(20-30 PERCENT) TO THE SOUTH.

A BELT OF STRONG 700 MB WINDS (40 KT) SHOULD ADVECT ACROSS THE
AREA DURING THE AFTERNOON. THIS AIR WILL BE QUITE DRY...AND FOR
ANY STORMS ABLE TO DEVELOP THIS SHOULD ENHANCE THEIR ABILITY TO
PRODUCE DAMAGING WINDS.

12Z MODELS ARE PRETTY CONSISTENT WITH THEIR DEPICTION OF WHERE THE
LOW SHOULD TRACK. HOWEVER THE 00Z ECMWF WAS ~50 MILES FARTHER
SOUTH WHICH WOULD SHIFT THE BEST POTENTIAL FOR STORMS INTO THE
BENNETTSVILLE-WHITEVILLE-WILMINGTON CORRIDOR. A FIRST-GLANCE AT
THE NEW 12Z ECMWF SHOWS IT NOW HAS THE LOW TRACKING ALMOST AS FAR
NORTH AS THE 12Z GFS/NAM MODELS...HOPEFULLY KEEPING THE CORRIDOR
OF BEST SEVERE WEATHER POTENTIAL JUST TO OUR NORTH.

THURSDAY NIGHT AND FRIDAY SHOULD BE QUIET AND UNEVENTFUL AS DRIER AND
COOLER AIR ARRIVES ON NORTHERLY WINDS. SURFACE HIGH PRESSURE
CENTERED TO OUR WEST WILL BUILD IN THROUGH THE WEEKEND. I HAVE
ADJUSTED FORECAST TEMPERATURES DOWNWARD BY A FEW DEGREES AS
LATEST MODELS SHOW NEAR-IDEAL RADIATIONAL COOLING CONDITIONS
OCCURRING IN AN UNSEASONABLY CHILLY AIRMASS.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AS OF 300 PM WEDNESDAY...WITH DRY SFC HIGH PRESSURE AND DECENT
RIDGING IN PLACE...EXPECT A FAIRLY QUIET PERIOD INTO EARLY NEXT
WEEK. WILL SEE A GRADUAL INCREASE OF TEMPERATURES THROUGH THE
MEMORIAL DAY WEEKEND FROM LOW/MID 80S TO MID/UPPER 80S ON
MONDAY...WITH OVERNIGHT LOWS IN THE LOW TO MID 60S. AS SFC HIGH
PRESSURE BEGINS TO SHIFT OFFSHORE...WILL SEE A NICE MOISTURE RETURN
BEGINNING AS EARLY AS MONDAY. WITH HIGH TEMPERATURES IN THE MID TO
UPPER 80S ON TUESDAY AND INCREASING HUMIDITY...COULD SEE SOME
ISOLATED TO SCATTERED SHOWERS IN THE AFTERNOON HOURS...WITH A
THUNDERSTORM POSSIBLE...MAINLY INLAND. INTO WEDNESDAY...PRECIPITABLE
WATER VALUES INCREASE TO OVER ONE AND A HALF INCHES...AND AHEAD OF
AN APPROACHING COLD FRONT ON WEDNESDAY. TIME OF ARRIVAL OF THE FRONT
ITSELF IS HARD TO DETERMINE ATTM AS SOME GUIDANCE SUGGESTS ITS
PROGRESSION MAY SLOW DOWN GIVEN WEAK RIDGING STILL IN PLACE. FOR NOW
HAVE CONTINUED SLIGHT CHANCE FOR SHOWERS/THUNDERSTORMS ON WEDNESDAY.
WITH OVERNIGHT LOWS INTO WEDNESDAY MORNING IN THE UPPER 60S...WILL
SEE HIGH TEMPERATURES IN THE MID 80S ALONG THE COAST...AND UPPER 80S
INLAND...WITH A FEW SPOTS POTENTIALLY HITTING 90 DEGREES.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...

AS OF 06Z...SHOWERS AND THUNDERSTORMS WERE LARGELY OFFSHORE...
ALTHOUGH AN ISOLATED SHOWER HAS DEVELOPED WEST OF INTERSTATE 95.
GUIDANCE STILL INSISTING THAT CONVECTION WILL DEVELOP OFFSHORE AND
ADVECT ON SOUTHERLY WINDS INTO KILM. HAVE MAINTAINED TEMPO -SHRA
TOWARDS DAWN FOR THIS ONE TERMINAL.

TOUGHER CHALLENGE CONTINUES TO BE FOG/STRATUS POTENTIAL OVERNIGHT.
GROUND IS SATURATED AND DEWPOINT DEPRESSIONS ARE TRENDING TOWARDS
ZERO. DO NOT EXPECT WIDESPREAD OR DENSE FOG OVERNIGHT THANKS TO
SURFACE WINDS THAT WON`T FULLY DECOUPLE NEAR THE COAST...AND A LLJ
RISING TOWARDS 20 KT. HOWEVER...ENOUGH NEAR-SURFACE SATURATION IS
STILL EXPECTED FOR SOME MVFR FOG...AT KCRE FOR LOCAL EFFECTS...AND
KFLO/KLBT THANKS TO LIGHTER WINDS. KFLO PROBABLY HAS THE BEST CHANCE
FOR IFR OVERNIGHT...BUT HAVE KEPT VSBYS JUST ABOVE IFR THRESHOLDS
SINCE FORECAST PROFILES SUGGEST JUST A VERY SHALLOW SATURATED
LAYER...WHICH COMBINED WITH THE INCREASING WINDS ABOVE THE INVERSION
SHOULD PRECLUDE DENSE FOG. PATCHY LOW STRATUS AT KILM IS NOT
EXPECTED TO BECOME A CEILING THROUGH SUNRISE.

ON THURSDAY...LOW PRESSURE WILL MOVE EAST AND DRAG A COLD FRONT
ACROSS THE AREA. SW WINDS AHEAD OF THE FRONT WILL GUST OVER 20 KT AT
ALL TERMINALS...AND THUNDERSTORMS ARE POSSIBLE IN THE AFTN/EVE. HAVE
NOT MENTIONED ANY TS ATTM...BUT WILL LIKELY SEE AT LEAST SCATTERED
STORMS...FAVORED AT KLBT/KILM...WHICH MAY NEED A TAF MENTION WITH
LATER ISSUANCES. COLD FRONT WILL CROSS OFFSHORE THURSDAY NIGHT
TURNING WINDS TO THE NORTH BY THE END OF THE VALID PERIOD.

EXTENDED OUTLOOK...VFR. FOG POSSIBLE MONDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1030 PM WEDNESDAY...A MEANDERING FRONTAL BOUNDARY TO EXIST
AND OCCUR ACROSS PORTIONS OF THE ILM NC AND SC WATERS THIS EVENING
AND OVERNIGHT. THIS SFC PRESSURE PATTERN COULD MAKE THE WIND
DIRECTION FORECAST A BIT CHALLENGING. WILL CONTINUE TO DOWNPLAY
THE OVERNIGHT EASTERLY WINDS ACROSS THE ILM WATERS NORTH OF CAPE
FEAR...AND TRANSITION TO A S TO SW DIRECTION. IN ADDITION...NOT
MUCH OF A SFC PG ON EITHER SIDE OF THE FRONTAL BOUNDARY
OVERNIGHT...WITH AROUND 10 KT LIKELY TO COVER OVERNIGHT WIND
SPEEDS. THE APPROACHING LOW FROM THE INLAND CAROLINAS LATE TONIGHT
WILL INCREASE THE WIND SPEEDS MAINLY AFTER THIS PERIOD.
SIGNIFICANT SEAS WILL BASICALLY RUN 2 TO 3 FT...AND BE COMPRISED
OF BOTH WEAK WIND DRIVEN WAVES AT 4 TO 5 SECOND PERIODS...AND A
LAZY 1 TO 1.5 FOOT GROUND SWELL AT 8 TO 9 SECOND PERIODS.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 PM WEDNESDAY...LOW PRESSURE WILL MOVE EASTWARD THROUGH
NORTH CAROLINA THURSDAY...BRINGING A BELT OF SOUTHWEST 15-20 KT WINDS
THROUGH THE AREA. A COLD FRONT WILL DIP SOUTH BEHIND THE DEPARTING
LOW THURSDAY EVENING...WITH NORTHERLY WINDS EXPECTED THROUGH
FRIDAY. THE STRONGEST NORTH WINDS ARE EXPECTED THURSDAY NIGHT INTO
EARLY FRIDAY WITH 15-20 KT POSSIBLE AT TIMES. THESE PERIODS OF
RELATIVELY STRONG WINDS SHOULD LAST LESS THAN 12 HOURS EACH...AND
THEREFORE SEAS ARE EXPECTED TO REMAIN BELOW 5 FEET.

LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 330 PM WEDNESDAY...HIGH PRESSURE WILL RESULT IN NE WINDS OF
10 TO 15 KT SATURDAY WHICH WILL VEER TO THE SE BY SUNDAY NIGHT.
SEAS OF 3 FT OR LESS ARE ON TAP FOR THE PERIOD.

&&

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

&&

$$
SYNOPSIS...TRA
NEAR TERM...DCH
SHORT TERM...TRA
LONG TERM...SGL
AVIATION...JDW/RJD


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