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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
120 AM EDT TUE APR 21 2015

.SYNOPSIS...
A COLD FRONT WILL MOVE OFF THE COAST AROUND DAYBREAK. DRY AND
SEASONABLE HIGH PRESSURE WILL BUILD ACROSS THE AREA TODAY AND
WEDNESDAY. ANOTHER COLD FRONT WILL CROSS THE COAST THURSDAY...
FOLLOWED BY MORE SEASONABLE WEATHER FRIDAY. A STORM SYSTEM MAY
AFFECT THE AREA SATURDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 130 AM TUESDAY...TRIMMED BACK POPS TO JUST THE CAPE FEAR
COASTAL COUNTIES FOR THE NEXT COUPLE OF HOURS. VEERING WINDS AND
DRIER AIR ADVECTING EASTWARD WITH THE COLD FRONT SHOULD END ANY
REMAINING INSTABILITY IN 2-3 HOURS. OTHERWISE...BIGGEST CHANGE TO
THE FORECAST WAS TO INCREASE FORECAST WIND SPEED AT THE NC BEACHES
WHERE THERE'S QUITE A LOW LEVEL JET BLASTING ONSHORE...WITH WIND
GUSTS OVER 30 MPH AT OCEAN CREST PIER IN THE PAST HOUR. DISCUSSION
FROM 1030 PM FOLLOWS...

THICK CANOPY OF MID TO UPPER LEVEL MOISTURE HAD LIMITED
INSOLATION FROM REACHING THE SFC THIS AFTN AND EARLY EVENING. THIS
HAS RESULTED WITH LESS SFC BASED INSTABILITY AVBL FOR POSSIBLE
CONVECTION AHEAD OF THE APPROACHING SFC COLD FRONT. LOOKING AT THE
CURRENT 88D RADAR MOSAIC ACROSS THE LOCAL FA AND UPSTREAM...SHOWER
AND THUNDERSTORM ACTIVITY HAS DWINDLED TO NEARLY NOTHING. WITH THE
ILM CWA WITHIN THE RIGHT REAR QUADRANT OF AN UPPER LEVEL JET THIS
EVENING...AND IN THE LEFT FRONT REGION OF AN APPROACHING JET
DURING THE PRE-DAWN TUE HRS...AND THE SFC COLD FRONT PUSHING
ACROSS THE FA PRIOR TO DAWN...WILL ALL PROVIDE THE DYNAMICS FOR
CONVECTIVE DEVELOPMENT. HOWEVER...SFC INSTABILITY REMAINS LACKING
ESPECIALLY WITH THE LOSS OF THE DAYS HEATING. WITH ALL THIS
SAID...HAVE ONCE AGAIN RE- ALIGNED THE REMAINDER OF THE EVENING
AND OVERNIGHT POPS AND SKY CONDITIONS. OVERALL...WILL KEEP
ISOLATED POPS ACROSS THE FA...MAINLY ALONG AND AHEAD OF THE CFP.
HAVE TWEAKED MIN TEMPS A DEGREE OR 2 LOWER...WHICH WILL OCCUR
AROUND OR JUST AFTER DAYBREAK TUE BASED ON HOW MUCH CAA OCCURS
AFTER THE CFP DURING THE EARLY AM TUE HRS.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 315 PM MONDAY...SPLIT FLOW PATTERN WILL PREVAIL AT THE MID
LEVELS THROUGH THE PERIOD WITH A GENERAL CYCLONIC PATTERN ACROSS
THE GREAT LAKES AND WESTERLY FLOW ACROSS THE SOUTHERN THIRD OF THE
U.S. THE GREAT LAKES TROUGH STRENGTHENS LATE IN THE PERIOD AND
DROPS SOUTH WITH A COLD FRONT MOVING ACROSS THE AREA BY EARLY
THURSDAY MORNING. I DID MAINTAIN THE SLIGHT CHANCE POPS WITH THIS
FEATURE AS MOST OF THE GUIDANCE IS INDICATING THIS. FOR TUESDAY
AND WEDNESDAY...NICE WEATHER PREVAILS UNDER WEAK HIGH PRESSURE.
THE ONLY ADJUSTMENT TO THE TEMPERATURE FORECAST WAS TO INCREASE
EXPECTED HIGHS FOR WEDNESDAY BASED ON THE LATEST GUIDANCE.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 315 PM MONDAY...SUFFICIENT MOISTURE MAY LINGER OVER MAINLY 
SOUTHERN ZONES AS A COLD FRONT IS SLOW TO EXIT THE AREA. MOISTURE 
WILL ALSO BE LIMITED BY MID LEVEL WESTERLY FLOW.  SOME LOWER 
DEWPOINTS ADVECT IN BEHIND THIS BOUNDARY ON FRIDAY WITH A WEAK HIGH 
TO OUR NORTH. CLOUDS INCREASE FRIDAY NIGHT AS THIS HIGH BEGINS TO 
GET OVERRUN BY SOME WARM AND MOIST ADVECTION. RAIN SHOULD OVERSPREAD 
THE REGION SOON THEREAFTER AS A FLAT WAVE OF LOW PRESSURE MOVES WEST 
TO EAST ACROSS THE FRONT STALLED TO OUR SOUTH. WITH THE EXIT OF THIS 
FEATURE SOME DRIER AIR ONCE AGAIN MANAGES TO PUSH IN FROM POINTS 
NORTH BRINGING BACK A DRY FORECAST IN ADDITION TO TEMPERATURES A 
SOLID CATEGORY BELOW CLIMO BY BOTH DAY AND NIGHT.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...                         
AS OF 06Z...AREA OF HIGH CLOUDS IS EXITING THE COASTAL AREAS WITH
DRIER AIR NOTED IN WATER VAPOR STREAMING INTO THE REGION FROM THE
WEST AND SOUTHWEST. AS A RESULT...HIGH CONFIDENCE THAT VFR
CONDITIONS WILL PREVAIL TONIGHT THROUGH TUESDAY NIGHT.
OTHERWISE... WINDS WILL VEER WITH THE APPROACH OF THE FRONT
THROUGH THE EARLY MORNING HOURS TUESDAY.

EXTENDED OUTLOOK...EXPECT VFR WITH POSSIBLE SHOWERS THURSDAY AND 
SATURDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 130 AM TUESDAY...SMALL CRAFT ADVISORY GUSTS ARE CERTAINLY
OCCURRING ACROSS THE NC WATERS...BUT SHOULD ABATE IN THE NEXT 2-3
HOURS AS THE COLD FRONT APPROACHES AND WIND DIRECTIONS VEER MORE
WESTERLY. ASIDE FROM PUSHING FORECAST WIND SPEEDS TO A SOLID 20
KNOTS...NO SIGNIFICANT CHANGES WERE MADE. DISCUSSION FROM 1030 PM
FOLLOWS...

SOLID SCEC FOR ALL WATERS. BORDERLINE SCA MAINLY FOR SEAS ACROSS
THE WATERS SOUTH OF CAPE FEAR TO LITTLE RIVER INLET.

SFC PRESSURE PATTERN AND TIGHTENED GRADIENT AHEAD OF THE
APPROACHING SFC COLD FRONT LATE THIS EVENING AND OVERNIGHT...
WILL PRODUCE SW WINDS AT 15 TO 20 KT...BECOMING SW-W AT 15 TO 20
KT WITH GUSTS UP TO 25 KT DURING THE PRE-DAWN TUE HOURS. THE
HIGHERRANGE OF SPEEDS TO ESPECIALLY OCCUR ACROSS THE OUTER
WATERS AWAY FROM THE FRICTIONAL AFFECTS OF THE IMMEDIATE COAST.
SIGNIFICANT SEAS WILL BASICALLY RUN 3 TO 5 FT...EXCEPT 4 TO 5 FT
WITH A FEW POSSIBLE 6 FOOTERS ACROSS THE OUTER WATERS SOUTH OF
CAPE FEAR TO LITTLE RIVER INLET. WITH A MORE WESTERLY COMPONENT TO
THE WINDS LATER TONIGHT...THE BETTER FETCH TO PRODUCE THE HIGHER
SEAS...IN THIS CASE THE 6 FOOTERS...MAY BE REALIZED. WIND DRIVEN
WAVES WILL BE THE PRIMARY CONTRIBUTOR TO THE SIGNIFICANT
SEAS...RESULTING IN DOMINANT PERIODS OF 5 TO 6 SECONDS.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 315 PM MONDAY...RELATIVELY WEAK HIGH PRESSURE WILL REMAIN 
ACROSS THE SOUTHEAST WITH A WESTERLY FLOW EMANATING FROM A DEEP 
CYCLONE WELL TO THE NORTH ACROSS THE CAROLINAS. THIS WILL MAINTAIN A 
LIGHT WESTERLY FLOW OF TEN KNOTS OR LESS ACROSS THE WATERS THROUGH 
MIDDAY WEDNESDAY. THE FLOW THEN BACKS TO THE SOUTHWEST AS A FRONT 
APPROACHES FROM THE NORTH. SPEEDS INCREASE AS WELL TO 10-15 KNOTS. 
INITIAL SEAS OF 2-4 FEET WILL DIMINISH TO AROUND TWO FEET EARLY 
WEDNESDAY BEFORE TRENDING UP AGAIN LATE.

LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 315 PM MONDAY...LIGHT WESTERLY FLOW ON THURSDAY AS A COLD FRONT 
ONLY VERY SLOWLY SAGS TO OUR SOUTH. WITH MORE SOUTHWARD PROGRESS OF 
THIS BOUNDARY THURSDAY NIGHT A NORTHERLY COMPONENT SHOULD BE ABLE TO 
MATERIALIZE. NORTH WINDS WILL THEN LIKELY LAST INTO FRIDAY. THE 
FRONT SHOULD RETURN CLOSER TO THE AREA ON SATURDAY AS A FLAT WAVE OF 
LOW PRESSURE TRAVERSES ITS LENGTH WEST TO EAST. WINDS SHALL REMAIN 
QUITE LIGHT BUT THERE MAY BE CONSIDERABLE VARIABILITY OF WIND 
DIRECTION BOTH THROUGH THE DAY AS WELL AS FROM NORTH TO SOUTH. THAT 
IS EASTERLY WINDS OVER NORTHERN WATERS WHILE SOUTHERN ZONES MAY VEER 
MORE TO SOUTHEASTERLY OR EVEN SOUTHERLY.

&&

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

&&

$$

SYNOPSIS...SHK
NEAR TERM...DCH/TRA
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...SRP

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