Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 170720
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
320 AM EDT WED SEP 17 2014

.SYNOPSIS...
A COLD FRONT WILL PUSH OFFSHORE EARLY THIS MORNING. HIGH PRESSURE
WILL EXTEND DOWN INTO THE CAROLINAS FROM THE NORTH BEHIND THIS
FRONT...PROVIDING FALL-LIKE WEATHER FOR THE REMAINDER OF THE WEEK.
THE NEXT COLD FRONT WILL MOVE THROUGH BY MONDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM WEDNESDAY...PRECIPITATION ASSOCIATED WITH A COLD FRONT
DROPPING SOUTH ACROSS THE FORECAST AREA IS MOVING EAST AND
TRANSITIONING TO A MORE STRATIFORM EVENT AS THE ATMOSPHERE
CONTINUES TO STABILIZE. HOWEVER..THERE IS STILL SOME
SHOWER/THUNDERSTORM ACTIVITY AS AN UPPER DISTURBANCE IMPINGES UPON
THE AREA. THIS DISTURBANCE IS INDUCING CYCLOGENESIS ALONG THE
FRONT...LIKELY OVER OUR FAR WESTERN COUNTIES...WHERE THE STRONGEST
CONVECTION IS OCCURRING.

A CONSENSUS OF GUIDANCE JUMPS FRONT OFFSHORE AND SOUTH OF THE
EASTERN CAROLINAS BY DAYBREAK AS CYCLOGENESIS STRENGTHENS OFF THE
COAST. FOR THE REMAINDER OF THE DAY AND OVERNIGHT...THE COMBINATION
OF HIGH PRESSURE BUILDING IN FROM THE NORTH AND LOW PRESSURE
OFFSHORE WILL BRING A SEASONALLY COOL EAST TO NORTHEASTERLY FLOW TO
THE AREA. HIGHS WILL RANGE FROM THE LOWER 80S UP NORTH TO THE MID
80S FURTHER SOUTH. WILL RETAIN THE LOW CHANCE OF CONVECTION TODAY
AND THIS EVENING AS MODEL SOUNDINGS INDICATE A MARGINALLY TO
MODERATELY UNSTABLE AIRMASS IN CONJUNCTION WITH A SERIES OF WEAK
UPPER IMPULSES DROPPING INTO THE BASE OF THE H/5 LONGWAVE TROUGH
LINGERING OVER EASTERN CONUS. A ADDITIONAL FACTOR FAVORING
PRECIPITATION TODAY WILL BE THE LOW LEVEL CONVERGENCE RESULTING FROM
WESTERLY WINDS ALOFT RIDING OVER EASTERLY WINDS BELOW.

OVERNIGHT LOWS WILL CONTINUE IN THE SEASONAL VEIN...WITH LOW RANGING
FROM THE LOWER 60S INLAND TO THE MID 60S CLOSER TO THE COAST AND
UPPER 60S AT THE BEACHES.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...SURFACE HIGH OVER THE GREAT LAKES THU WILL
SHIFT EAST TO NEW ENGLAND FRI...SETTING UP A CLASSIC WEDGE. LIGHT
NORTHEAST FLOW THU AND LIMITED LOW LEVEL MOISTURE MAY ALLOW FOR SOME
SUNSHINE BUT INCREASED NORTHEAST FLOW AND LOW LEVEL MOISTURE FRI
WILL LIKELY LEAD TO AN INCREASE IN CLOUD COVER. PRECIP CHANCES ARE
RATHER LIMITED EACH DAY WITH WEAK SUBSIDENCE ALOFT KEEPING THE MID
LEVELS DRY. THE ONLY REAL THREAT APPEARS TO BE ALONG THE IMMEDIATE
COAST WHERE LOW LEVEL MOISTURE IS HIGHEST...ESPECIALLY FRI...AND
SOME LIGHT RAIN COULD DEVELOP. MEASURABLE RAINFALL WILL BE DIFFICULT
TO COME BY EVEN IF LIGHT RAIN DEVELOPS SO PLAN TO CONTINUE CARRYING
SLIGHT CHC/LOW CHC ALONG THE COAST WITH POP AROUND 10 INLAND.

NORTHEAST FLOW WILL HELP KEEP HIGH TEMPERATURES ALONG THE COAST A
LITTLE BELOW CLIMO THROUGH THE PERIOD. FARTHER INLAND HIGHS WILL BE
NEAR CLIMO WITH A LITTLE MORE SUN AND A LITTLE LESS MARINE
INFLUENCE. LOW TEMPERATURES WILL END UP A LITTLE ABOVE CLIMO DUE TO
CLOUDS AND BOUNDARY LAYER MIXING.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM WEDNESDAY...HIGH PRESSURE WEDGE IN PLACE AT THE START OF
THE PERIOD WILL HOLD ON INTO AT LEAST THE SECOND HALF OF THE
WEEKEND...KEEPING TEMPERATURES IN MOST AREAS A LITTLE BELOW CLIMO.
GUIDANCE IS SHOWING HINTS THE WEDGE COULD HOLD ON INTO MON GIVEN THE
LACK OF SURFACE AND MID LEVEL FEATURES. THIS WOULD MAINTAIN LOW
CLOUDS AND LIGHT PRECIP...MAINLY ALONG THE COAST...INTO NEXT WEEK.
FARTHER INLAND THERE IS LIKELY TO BE A NARROW GRADIENT BETWEEN
MOSTLY CLOUDY AND MOSTLY SUNNY. THIS IS COMPLICATED SOMEWHAT BY
POTENTIAL WEAK LOW PRESSURE DEVELOPING ALONG THE FRONT STALLED
OFFSHORE. THIS FEATURE COULD ENHANCE THE WEDGE AS IT MOVES UP THE
COAST BEFORE HELPING TO BREAK THE WEDGE AS IT EXITS NORTHEAST.
HOWEVER ITS INFLUENCE ON THE AREA REMAINS IN QUESTION WITH MANY OF
THE MEDIUM RANGE SOLUTIONS KEEPING THIS FEATURE ON THE WEAK SIDE AND
FARTHER OFF THE COAST.

COLD FRONT APPROACHES FROM THE NORTHWEST MON...DRIVEN SOUTH BY
STRONG MID LEVEL TROUGH DIVING SOUTH ACROSS THE GREAT LAKES AND
CANADIAN HIGH PRESSURE. FROPA DURING THE DAY MON WILL HAVE SOME
DIURNAL INSTABILITY TO WORK WITH...BUT HOW MUCH REMAINS A QUESTION.
EXPECT CONVECTION AHEAD OF THE FRONT BUT STRENGTH AND COVERAGE WILL
PARTLY DEPEND ON TIMING. FRONT STALLS OFFSHORE MON NIGHT INTO
TUE...SIMILAR TO THIS WEEKS COLD FRONT AS SURFACE HIGH BUILDS IN
FROM THE GREAT LAKES.

&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
AS OF 06Z...THE HRRR SUGGESTS SLOW-MOVING SHOWER/TSTM ACTIVITY
ALONG THE COLD FRONT MAY STILL PLAGUE OUR INLAND TAF SITES AT THE
START OF THE PERIOD. THEREFORE WILL INCLUDE VCSH FOR KFLO/KLBT
FROM 06-08Z. INCREASING DEBRIS CLOUDS FROM FRONTAL CONVECTION WILL
LIKELY LIMIT FOG POTENTIAL OVERNIGHT. HAVE JUST INCLUDED TEMPO
MVFR VSBYS... MAINLY EARLY IN THE PERIOD AS THE NORTHEASTERLY
SURGE AFTER 09Z OR SO SHOULD MIX OUT ANY LINGERING BR. COULD ALSO
SEE SOME MVFR CIGS DEVELOP BEHIND THE FRONT THIS MORNING...BUT IFR
POTENTIAL APPEARS LOW EVEN FOR THE INLAND TERMS. MVFR CIGS COULD
LINGER THROUGH THE LATE MORNING HOURS BEFORE IMPROVING TO VFR BY
MIDDAY. EXPECT NE WINDS AOB 10 KT BEHIND THE FRONT TO PERSIST
THROUGH THE PERIOD.

EXTENDED OUTLOOK...EARLY MORNING MVFR/IFR CIGS POSSIBLE ON THU.
GUSTY NORTHEAST WINDS EXPECTED FRI/SAT AS THE COOL AIR WEDGE
STRENGTHENS OVER THE CAROLINAS. VFR ON SUNDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 3 AM WEDNESDAY...A LIGHT EAST TO NORTHEASTERLY FLOW OF
AROUND 10 KTS WILL DEVELOP OVER THE WATERS TODAY AND TONIGHT AS A
COLD FRONT DROPS SOUTH OF THE AREA. WIND WAVES WILL BE IN THE
MODEST 1 TO 2 FT RANGE...BUT WILL BE SUPPLEMENTED BY SWELL FROM
DISTANT HURRICANE EDOUARD...BRINGING A COMBINED SEA HEIGHT RANGING
FROM 2 TO 4 FT.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY....LIGHT NORTHEAST FLOW ON THU WILL INCREASE
SIGNIFICANTLY FRI AS HIGH PRESSURE BUILDS DOWN THE COAST AND
GRADIENT BECOMES PINCHED. THU NORTHEAST FLOW WILL BE IN THE REALM OF
10 KT BUT BY MIDDAY FRI SOLID 20 KT WITH HIGHER GUSTS IS EXPECTED.
SEAS 2 TO 4 FT THU FLIRTS WITH HEADLINE CRITERIA FRI...ESPECIALLY
NORTH OF CAPE FEAR...BUILDING TO 4 TO 5 FT WITH POTENTIAL FOR 6 FT
ACROSS PARTS OF NC WATERS.

LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 3 AM WEDNESDAY....ELEVATED NORTHEAST FLOW CONTINUES SAT AS
HIGH PRESSURE RIDGES DOWN THE COAST. GRADIENT WILL MAINTAIN 15 TO 20
KT WINDS SAT BUT WEAKENING GRADIENT SUN WILL ALLOW FOR A REDUCTION
IN SPEEDS. WEAK LOW PRESSURE PASSES EAST OF THE WATERS SUN. IN THE
WAKE OF THIS LOW SUN NIGHT LIGHT SOUTHWEST FLOW WILL DEVELOP. SEAS 3
TO 5 FT WITH OCCASIONAL 6 FT POSSIBLE SAT DECREASE TO 2 TO 4 FT SUN.

&&

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

&&

$$

NEAR TERM...REK
SHORT TERM...III
LONG TERM...III
AVIATION...BJR





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