Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 121047
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
648 AM EDT SAT APR 12 2014

.SYNOPSIS...
HIGH PRESSURE WILL CONTROL THE WEATHER PATTERN THROUGH EARLY NEXT
WEEK...SUPPORTING DRY AND MILD CONDITIONS. A COLD FRONT WILL MOVE
ACROSS THE AREA TUESDAY...WITH INCREASING CHANCES FOR SHOWERS. HIGH
PRESSURE WILL RETURN TO THE CAROLINAS WEDNESDAY THROUGH FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...SURFACE HIGH PRESSURE ACROSS THE
WEST-CENTRAL ATLANTIC CONTINUES TO EXTEND A RIDGE AXIS BACK INTO THE
SOUTHEASTERN UNITED STATES. FOR THE PAST TWO DAYS THIS RIDGE WAS
CENTERED ACROSS NORTHERN FLORIDA...BUT THE RIDGE WILL PUSH GRADUALLY
NORTHWARD TODAY AND TONIGHT WITH A SUBSEQUENT BACKING OF OUR
LOW-LEVEL WIND FIELD.

STEEP LAPSE RATES AGAIN TODAY (DRY ADIABATIC UP THROUGH 6000 FEET)
WILL COMBINE WITH A LITTLE HIGHER DEWPOINTS ALONG THE COAST TO
DEVELOP A HEALTHIER CUMULUS FIELD BY EARLY AFTERNOON. THE HRRR MODEL
ACTUALLY SHOWS ISOLATED SHOWERS DEVELOPING 5-25 MILES INLAND FROM
THE BEACHES DURING THE HEAT OF THE DAY. THIS IS INTERESTING SINCE
THE HRRR EXPLICITLY MODELS CONVECTIVE CELLS UNLIKE THE GFS/NAM WHICH
BOTH PARAMETRIZE CONVECTION. VERY LIGHT STEERING FLOW IN THE 750-900
MB LAYER SHOULD PRODUCE LITTLE NET MOVEMENT OF ANY SHOWERS... SO I
AM ONLY INCLUDING A TOKEN 5% POP BETWEEN I-95 AND THE COAST. HIGHS
79-82 ARE EXPECTED INLAND FROM THE BEACHES TODAY.

TONIGHT...GOOD RADIATIONAL COOLING UNDER THE SURFACE RIDGE PLUS
HIGHER DEWPOINTS THAN WE`VE SEEN OVER THE PAST FEW DAYS WILL PRODUCE
PATCHY FOG AND POTENTIALLY SOME LOW STRATUS LATE. LOWS SHOULD FALL
INTO THE MID-UPPER 50S.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS TO 330 AM SATURDAY...WARM WEATHER WILL CONTINUE WITH
INCREASING CHC OF SHOWERS TOWARD THE END OF THE PERIOD...BY LATE
MONDAY...AS HIGH PRESSURE SLIPS FARTHER OFF SHORE AND A COLD FRONT
APPROACHES THE CAROLINAS FROM THE WEST.

ATLANTIC RIDGE HOLDING ON BUT SHIFTING FARTHER EAST AS A DIGGING
MID TO UPPER TROUGH PUSHES A COLD FRONT EAST. THIS WILL PRODUCE AN
INCREASING SOUTHERLY RETURN FLOW WITH WINDS INITIALLY SOUTHEAST
AROUND 5 TO 10 MPH ON SUNDAY BUT VEERING AROUND TO S TO SW BY
LATE MONDAY AND INCREASING UP TO 15 MPH OR SO AT THE SFC AND UP TO
30 TO 40 KTS IN THE LOW LEVELS. THIS WILL HELP TO INCREASE THE
MOISTURE THROUGH THE COLUMN. THE MID LEVELS WILL STAY DRY UNTIL
LATER ON MONDAY WHEN WE BEGIN TO TAP INTO GREATER GULF MOISTURE.
PCP WATER VALUES WILL INCREASE FROM CLOSER TO A HALF INCH ON SUNDAY
UP TO 1.5 INCHES BY MON LATE AFTN. THE INCREASING MOISTURE AND
LIFT LATE SUNDAY INTO MONDAY WILL CAUSE SOME CLOUDS TO DEVELOP BUT
OVERALL BEST CHC OF PCP WILL COME LATE MON AND MORE SO ON TUES AS
COLD FRONT MAKES IT INTO THE CAROLINAS. EXPECT MAIN FORCING TO
COME IN THE WAY OF CONVERGENCE ASSOCIATED WITH SEA BREEZE AND
LARGER SCALE CONVERGENCE AROUND ATLANTIC RIDGE WITH SOME SHOWERS
FEEDING INTO AREA FROM THE ATLANTIC WATERS. TEMPS WILL REACH UP
AROUND 80 WITH OVERNIGHT LOWS UP NEAR 60 OR ABOVE.


&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 AM SATURDAY...INCREASINGLY MOIST AND UNSTABLE AIR MASS
IN PLACE ON TUESDAY AS COLD FRONT MAKES ITS WAY THROUGH THE
CAROLINAS. DEEP LAYER MOISTURE WILL BE PRESENT WITH PCP WATER
VALUES UP AROUND 1.75 INCHES TUES AFTN. DEWPOINT TEMPS WILL SURGE
INTO THE MID 60S WHILE TEMPS WILL REACH INTO THE 80S. DECENT
DYNAMICS ALOFT INCLUDING A STRONG LLJ...DEEPENING MID TO UPPER
TROUGH AND A STRONG UPPER LEVEL JET WILL COMBINE TO PRODUCE SHWRS
AND THUNDERSTORMS ON TUES AHEAD AND ALONG COLD FRONT. WILL WAIT TO
INCLUDE ANY MENTION OF STRONG TO SVR STORMS BUT AT THIS TIME IT
DOES LOOK LIKE THERE WILL BE SOME STRONG STORMS POSSIBLE
ESPECIALLY OVER INLAND PORTIONS OF CWA.

COLD FRONT SHOULD CROSS THE AREA BY TUES NIGHT WITH COOL AND DRY
HIGH PRESSURE BUILDING IN BEHIND IT. MODELS HINTING AT A WEDGE
SIGNATURE DEVELOPING WHICH MAY LEAVE LOW CLOUDS IN THE FORECAST
FOLLOWING THE FRONT FOR MID WEEK. FOR NOW WILL GO WITH SOME PERIODS
OF CLOUDS DEVELOPING AND OVERALL COOLER TEMPS IN STRONGER NORTH TO
NORTHEAST FLOW BEHIND FRONT FOR WED THROUGH FRI. THERE WILL BE A
GRADUAL WARMING EACH DAY.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...A WEAK COLD FRONT WILL DROP SOUTHWARD...BUT WILL WEAKEN
AND NOT MOVE INTO THE REGION. HIGH PRESSURE OFFSHORE WILL GIVE US
SOUTHWESTERLY FLOW TODAY...BECOMING SOUTHERLY AND STRONGER ALONG THE
COAST WITH THE RESULTANT. LIGHT WINDS TONIGHT WITH SOME SCATTERED
CIRRUS IN AND OUT OF THE REGION.

EXTENDED OUTLOOK...MORNING FOG POSSIBLE ON SUNDAY. CHANCE OF
SHOWERS AND MVFR CONDITIONS LATE MONDAY INTO TUESDAY WITH SHOWERS
AND/OR THUNDERSTORMS ALONG A PASSING COLD FRONT. OTHERWISE VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM SATURDAY...ALTHOUGH HIGH PRESSURE IS CENTERED MANY
HUNDREDS OF MILES OFF THE U.S. EAST COAST...A RIDGE AXIS EXTENDING
WEST FROM THIS HIGH LIES ACROSS GEORGIA AND ALABAMA. THIS RIDGE
AXIS SHOULD DRIFT NORTHWARD TONIGHT...WITH LIGHT WINDS GRADUALLY
BACKING MORE SOUTHEASTERLY WITH TIME. OUTSIDE OF THIS AFTERNOON`S
SEABREEZE WIND SPEEDS SHOULD REMAIN UNDER 10 KNOTS...WITH SEAS
ONLY 2 FEET. THE SEABREEZE WILL ADD ABOUT 5 KNOTS NEARSHORE THIS
AFTERNOON INTO THE EARLY EVENING.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS TO 330 AM SATURDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF THE
COAST AS COLD FRONT NEARS THE CAROLINAS BY LATE MONDAY. THIS WILL
PRODUCE AN INCREASING SOUTHERLY RETURN FLOW THROUGH MONDAY. WINDS
WILL START OUT S-SE REMAINING 10-15 KTS OR BELOW KEEPING SEAS NO
HIGHER THAN 2-3 FT. WINDS AND SEAS WILL THEN INCREASE AND BUILD
ON MONDAY AS THE PRESSURE GRADIENT TIGHTENS WITH APPROACH OF COLD
FRONT. SHOULD SEE SEAS BUILD INTO SCA THRESHOLDS BY LATE MONDAY IN
INCREASING SOUTHERLY WINDS UP TO 20 TO 25 KTS.

LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS TO 330 AM SATURDAY...SCA CONDITIONS WILL PERSIST AS STRONG
SOUTHERLY FLOW AHEAD OF APPROACHING COLD FRONT REACHES UP NEAR 25
KTS. THIS WILL PUSH SEAS UP NEAR 6 TO 7 FT THROUGH TUES WITH A
SLIGHT DROP AS FRONT CROSSES THE WATERS TUES EVENING INTO EARLY
WED. ONCE THE FRONT CROSSES THE WATERS A STRONG NORTHERLY SURGE
WILL BRING SEAS BACK UP TO 6 TO 8 FT IN THE OUTER WATERS THROUGH
MID WEEK. A PINCHED GRADIENT WILL DEVELOP AS HIGH PRESSURE WEDGES
DOWN THROUGH THE CAROLINAS PRODUCING A PROLONGED PERIOD OF STRONG
N-NE WINDS.

&&

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

&&

$$

NEAR TERM...TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...43








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