Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 231147
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
747 AM EDT SAT MAY 23 2015

.SYNOPSIS...
HIGH PRESSURE CENTERED TO OUR NORTH WILL CONTINUE TO RIDGE ACROSS
THE FORECAST AREA AS IT SLOWLY SHIFTS OFFSHORE THROUGH THE HOLIDAY
WEEKEND. HIGHER HUMIDITY LEVELS WILL RETURN NEXT WEEK ALONG WITH A
SMALL RISK FOR SHOWERS AND THUNDERSTORMS BEGINNING WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 600 AM SATURDAY...A CLOUDLESS AND COOL START TO THE DAY.

COOL HIGH PRESSURE WAS CENTERED ACROSS PENNSYLVANIA EARLY THIS
MORNING AND WAS RIDGING STRONGLY SOUTHWARD ACROSS THE CAROLINAS. A
FRONT...THE LEADING EDGE OF EVEN DRIER AIR...WAS DROPPING SOUTH
ACROSS VIRGINIA. THIS FRONT WILL LOSE ITS SOUTHWARD PUSH AND
BECOME ILL- DEFINED AS THE CENTER OF HIGH PRESSURE SLOWLY SHIFTS
OFFSHORE OF THE MID-ATLANTIC STATES THROUGH TONIGHT. THE HIGH WILL
RIDGE BACK ACROSS THE EASTERN CAROLINAS TONIGHT. THE LOW-LEVEL
FLOW WILL SHIFT FROM NE THIS MORNING TO E AND ESE THIS AFTERNOON
AND TONIGHT. THE ONSHORE FLOW WILL GRADUALLY INCREASE THE SUPPLY
OF LOW-LEVEL MOISTURE. MINIMUM AFTERNOON RELATIVE HUMIDITY LEVELS
WILL STILL BE LOW INLAND...AROUND 30 PERCENT.

EXCEPT FOR SOME THIN CIRRUS WISPS...IT WILL BE SUNNY TODAY. EVEN
FLAT CUMULUS ATOP THE MIXED LAYER WILL BE HARD TO COME BY DURING
PEAK HEATING. TONIGHT...THE WINDS ABOVE THE BOUNDARY LAYER WILL
INCREASE AND THIS SHOULD BE ENOUGH TO LIMIT ANY WIDESPREAD FOG
CONCERNS. HOWEVER...WOULD EXPECT SOME PATCHY LATE NIGHT FOG TO
DEVELOP. AS MOISTURE INCREASES IN THE 4-6 KFT LAYER...WE MAY BEGIN
TO SEE SOME STRATOCUMULUS DEVELOP OR ADVECT INTO THE AREA FROM
OFFSHORE.

WE WILL BEGIN THE DAY UNSEASONABLY COOL WITH TEMPS IN THE LOWER TO
MID 50S...BUT NOT QUITE AS COOL AT THE BEACHES. BRIGHT SUNSHINE WILL
REBOUND AFTERNOON HIGHS INTO THE COMFORTABLE LOWER 80S. AN ONSHORE
FLOW WILL KEEP HIGHS AT THE BEACHES AND NEARBY ENVIRONS IN THE UPPER
70S. NOT AS COOL TONIGHT WITH LOWS IN THE UPPER 50S TO NEAR 60
DEGREES INLAND AND LOWER TO MID 60S ALONG THE MORE COASTAL LOCATIONS.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED AS NEARLY
PICTURE PERFECT WX FOR THIS MEMORIAL HOLIDAY WEEKEND. NOT TOO HOT
NOR COLD. NO PRECIPITATION...AND...MOSTLY SUNNY SKIES EACH DAY
AND MOSTLY CLEAR SKIES EACH NIGHT.

MID AND UPPER LEVEL RIDGING OVERHEAD TO AFFECT THE FORECAST AREA.
IN FACT...THE MID-UPPER LEVEL HIGH WILL BE ANCHORED JUST OFF THE
SOUTHEAST U.S. COAST...WITH ITS SOUTH TO NORTH RIDGE AXIS JUST
WEST OF THE ILM CWA SUNDAY...WILL DRIFT TO A POSITION THATS NEARLY
OVERHEAD BY MONDAY NIGHT. SFC HIGH PRESSURE CENTERED JUST OFF THE
DELMARVA COAST ON SUNDAY...WILL DRIFT EASTWARD AND FURTHER
OFFSHORE BY MONDAY NIGHT. ITS SFC RIDGE AXIS WILL EXTEND WSW INTO
NC AND FOR THE MOST PART ITS AXIS TO REMAIN NORTH OF THE ILM CWA.
THIS POSITION WILL RESULT WITH AN ONSHORE FLOW PATTERN THAT WILL
EXTEND UPWARDS TO NEAR 850MB. THIS PATTERN WILL RESULT IN THE DAILY
MAX AND MIN TEMPS RUNNING AT OR JUST BELOW CLIMO. THE MOISTURE IN
THE LOWER LEVELS WILL INCREASE DUE TO THE ONSHORE FLOW...AND
LIKELY BE USED TO PRODUCE DIURNALLY DRIVEN SCATTERED CU EACH
DAY...ESPECIALLY ALONG THE DAILY RESULTANT WIND BOUNDARY AKA THE
SEA BREEZE. IN ADDITION TO THE CU...CONVECTIVE DEBRIS CLOUDS IN
THE FORM OF THIN TO OCCASIONALLY OPAQUE CIRRUS WILL OCCASIONALLY
SPILL OVER THE UPPER RIDGE AXIS AND ACROSS THE ILM CWA. AS FOR
TEMPS...STAYED WITH THE MODEL MOS GUIDANCE EXHIBITING THE LOWER
MAX/MINS.

WITH AN ONSHORE FLOW ACROSS A DECENT FETCH FOR BOTH DAYS...EXPECT
AN E TO SE GROUND SWELL TO INCREASE IN SIZE...AND ALSO BECOME
PERPENDICULAR TO THE AREA BEACHES. THIS WILL LIKELY INCREASE THE
RIP CURRENT THREAT FOR AREA BEACHES THRUOUT THE ILM CWA.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 330 AM SATURDAY...THE MID TO UPPER LEVEL RIDGE AXIS TO BE
NEARLY OVERHEAD ON TUESDAY...THEN SLIGHTLY DRIFT JUST OFF THE
SOUTHEAST U.S. COAST TOWARD THE END OF THE WEEK. THIS A RESULT OF
UPSTREAM FORCING TRYING TO PUSH/PROGRESS THIS FEATURE EASTWARD.
HOWEVER...A FLY IN THE OINTMENT IN THE FORM OF A MID-UPPER LOW
OVER THE MID-ATLANTIC OCEAN APPROACHING THE US MAINLAND FROM THE
SOUTHEAST. IT LOOKS OMINOUS ALOFT...HOWEVER AT THE SFC...THERE IS
NO ACCOMPANYING STRONG SFC LOW...JUST A TROF OF LOW PRESSURE. THIS
UPPER LOW WILL SLOW THE PROGRESSION OF THE UPPER RIDGE
EASTWARD...AND THUS ALLOW THE CONTINUANCE OF DECENT WX CONTINUING
THRU THE END OF THE WORK WEEK OF NEXT WEEK. ENOUGH SUBSIDENCE
ALOFT WILL PREVENT WIDESPREAD PCPN...HOWEVER THE FORCING FROM THE
DAILY SEA BREEZE WILL LIKELY BE ENOUGH TO CARRY A LOW CHANCE FOR
CONVECTION. MOISTURE IN THE FORM OF CLOUDS COULD REACH THE COASTAL
CAROLINAS AS THE MID-ATLANTIC UPPER LOW REACHES ITS CLOSEST
APPROACH ON FRI. FOR NOW HAVE KEPT ANY PCPN ASSOCIATED WITH IT
WELL OFFSHORE FROM THE MAINLAND. HAVE ALSO PREVENTED THE PCPN WEST
OF THE ILM CWA FROM MOVING EASTWARD INTO THE ILM CWA...AS THE FA
REMAINS SANDWICHED BETWEEN THE ATLANTIC LOW AND THE MID-UPPER
TROF ALONG THE SPINE OF THE APPALACHIANS. MAX/MIN TEMPS THRU THIS
PERIOD WILL BE JUST ON EITHER SIDE OF CLIMO.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AS OF 12Z...HIGH PRESSURE WILL ALLOW FOR VFR TO PREVAIL THROUGH THE
VALID TAF PERIOD.

LIGHT NORTHEAST WINDS THIS MORNING WILL SHIFT THIS AFTERNOON
BECOMING EAST-SOUTHEAST AND INCREASING TO AOB 10 KTS. SLIGHTLY
HIGHER SUSTAINED WINDS ARE POSSIBLE ALONG THE COAST...WITH GUSTS
AROUND 18 KTS POSSIBLE. NEARLY CLEAR SKIES ARE EXPECTED
THROUGHOUT THE PERIOD...WITH FEW CU AND THIN CIRRUS POSSIBLE.
INTO THE OVERNIGHT HOURS WINDS WILL BECOME LIGHT.

EXTENDED OUTLOOK...MORNING FOG POSSIBLE MONDAY AND WEDNESDAY.
OTHERWISE EXPECT VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 600 AM SATURDAY...A VERY MODEST MINI SURGE WILL END THIS
MORNING AS COOL AND DRY HIGH PRESSURE TO THE NORTH MAKES ITS FINAL
PUSH SOUTHWARD. THE HIGH WILL GRADUALLY SHIFT OFFSHORE OF THE MID-
ATLANTIC STATES THROUGH TONIGHT AS IT RIDGES BACK ACROSS THE
CAROLINA WATERS. NE WINDS EARLY THIS MORNING WILL SHIFT TO E AND
ESE FOR THE REMAINDER OF THE DAY AND TONIGHT. WIND SPEEDS WILL
GENERALLY BE 10 TO 15 KT. SEAS WILL BE 2 TO 3 FT TODAY AND 3 TO 4
FT TONIGHT AS AN INCREASING EASTERLY FETCH AROUND OFFSHORE HIGH
PRESSURE BRINGS A WEAK ESE SWELL INTO THE WATERS ON THE ORDER OF 9
TO 10 SECONDS.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 330 AM SATURDAY...THE SFC RIDGE AXIS FROM THE HIGH OFFSHORE
FROM THE DELMARVA COAST...IS PROGGED TO EXTEND WSW INTO NC BUT
REMAIN FOR THE MOST PART NORTH OF THE ILM WATERS. THIS WILL RESULT
IN AN ONSHORE E-SE FLOW THRU THIS PERIOD. EXPECT A SEMI-TIGHTENED
SFC PG SOUTH OF THE SFC RIDGE AXIS...THUS RESULTING IN SPEEDS
AROUND 15 KT. WITH A DECENT FETCH...EXPECT SIGNIFICANT SEAS TO
BUILD TO 3 TO 4 FT...POSSIBLY A FEW 5 FOOTERS LATE MON NIGHT. IN
ADDITION...LOOK FOR INCREASING PERIODS THAT COULD RESULT IN WIND
DRIVEN WAVES TRANSITIONING INTO A PSEUDO GROUND SWELL.

LONG TERM /TUESDAY THROUGH WEDNESDAY/...
AS OF 330 AM SATURDAY...WEAKENING UPPER RIDGING TO HOLD ON THRU
WEDNESDAY AS IT BECOMES SANDWICHED ACROSS THE AREA WATERS. THIS
DUE TO THE APPROACHING MID-UPPER MID-ATLANTIC LOW FROM THE
SE...AND AN UPPER TROF TRYING TO PROGRESS EASTWARD ACROSS EASTERN
U.S. AND GETS HUNG UP ALONG THE WINDWARD SIDE OF THE APPALACHIANS.
THE SFC PRESSURE PATTERN ACROSS THE LOCAL WATERS WILL RESULT IN SE
WINDS AT 10 TO 15 KT....LIKELY A SOLID 15 KT ACROSS THE
SOUTHERNMOST WATERS DUE TO AN INCREASED SFC PG. NO REAL SFC ENTITY
ACCOMPANYING THE MID-ATLANTIC UPPER LOW...JUST A SFC TROF
EXHIBITED BY THE MODELS. BUT WITH A DECENT E-SE FETCH CONTINUING
TO OCCUR...LOOK FOR A SOLID 3 TO 4 FT SEAS WITH 5 FOOTERS NOT OUT
OF THE QUESTION AS WAVEWATCH3 ILLUSTRATES.

&&

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

&&

$$

NEAR TERM...RJD
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...SGL


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