Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 221038
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
639 AM EDT FRI MAY 22 2015

.SYNOPSIS...
HIGH PRESSURE AND MUCH DRIER AIR WILL BUILD INTO REGION AND
CONTINUE INTO THE WEEKEND. HIGH PRESSURE WILL SHIFT OFFSHORE EARLY
NEXT WEEK WITH HIGHER HUMIDITY LEVELS RETURNING TO THE AREA.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 600 AM FRIDAY...A COLD FRONT HAS MOVED WELL OFFSHORE AND
HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE FORECAST AREA FROM
THE NW AND N. AN INVERSION HAS TRAPPED MOISTURE AROUND 5 KFT EARLY
THIS MORNING...KEEPING A GOOD DEAL OF MID CLOUDS ACROSS THE
FORECAST AREA. THIS INVERSION SHOULD ERODE MID TO LATE MORNING...
ALLOWING THESE CLOUDS TO DISSIPATE. AT THE SAME TIME...JET CIRRUS
IS EXPECTED TO BE THINNING. WE MAY SEE SOME FLAT CUMULUS ATOP THE
MIXED LAYER MIDDAY AND THIS AFTERNOON...BUT OTHERWISE IT WILL BE A
MOSTLY SUNNY AFTERNOON.

DEWPOINTS ARE EXPECTED TO DROP INTO THE 40S TODAY...THAT IS A 25
TO 30 DEGREE TURN AROUND FROM THU...SO FOR MOST...IT WILL FEEL
MUCH MORE COMFORTABLE. RELATIVE HUMIDITY VALUES WILL BE AS LOW AS
AROUND 30 PERCENT THIS AFTERNOON. TEMPS AT 850 MB WILL BE COOLING
TO AROUND 10 DEG C AND THIS SHOULD KEEP HIGHS TODAY IN THE MID AND
UPPER 70S.

EXCEPT FOR SOME CIRRUS...SKIES WILL BE CLEAR TONIGHT. HIGH PRESSURE
WILL BE CENTERED ACROSS PENNSYLVANIA AND THE NORTHERN MID-ATLANTIC
OVERNIGHT. WE DO EXPECT WINDS WILL BE LIGHT AND WITH THE DRY AIR
IN PLACE...LOWS SHOULD DROP INTO THE 50S AND AS COOL AS THE LOWER
50S. THE BEACHES WILL BE WARMEST...AROUND 60 DEG.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 200 AM FRIDAY...MID-LEVEL NORTH TO SOUTH TROF LINE INITIALLY
OVER THE FORECAST AREA...WILL SLIDE OFF THE EAST COAST DURING
SATURDAY. AT THE SAME TIME...MODELS INDICATE SOME AMPLIFICATION WITH
THE UPPER TROF/LOW COVERING AN AREA FROM THE WEST COAST OF THE U.S.
TO THE ROCKIES. GIVEN THE YING/YANG PRINCIPLE...THIS AMPLIFICATION
WITH THE UPPER TROF WILL RESULT IN THE AMPLIFICATION OF THE UPPER
RIDGE ACROSS THE EASTERN U.S...WITH THE UPPER RIDGE AXIS EXTENDING
FROM THE SOUTHEAST U.S. TO THE SOUTHERN GREAT LAKES. THE UPPER HIGH
ITSELF WILL REMAIN CENTERED OVER THE SE STATES. AT THE SFC...MODELS
ILLUSTRATE THE CENTER OF THE 1030+ MB SFC HIGH WILL DROP SE-WARD
FROM THE GREAT LAKES TO THE MID-ATLANTIC COAST DURING SATURDAY...AND
BECOME CENTERED OFFSHORE FROM THE ILM NC COAST DURING SUNDAY. THE
SFC RIDGE AXIS FROM THE HIGHS CENTER WILL CONTINUE TO EXTEND
WESTWARD BACK ACROSS THE ILM CWA THROUGH SUNDAY NIGHT. THIS PATTERN
WILL KEEP POPS AT BAY...AND FOR THE MOST PART CLOUDINESS TOO. BY
LATE SUNDAY INTO SUNDAY NIGHT...THE NORTH TO SOUTH UPPER RIDGE AXIS
WILL BE AT ITS CLOSEST APPROACH TO THE ILM CWA....BUT STILL
REMAINING WEST OF THE FA. COULD SEE DEBRIS CLOUDINESS IN THE FORM OF
CI/CS AND POSSIBLY ALTOCU TRACK ACROSS THE UPPER RIDGE AXIS AND
ACROSS THE FA WHILE AT THE SAME TIME SCOURING OUT AS THE CLOUDS
TRACK WITHIN A DOWNSLOPE TRAJECTORY OFF THE APPALACHIANS. THE MAIN
AND DEEPER CLOUD SHIELD WILL REMAIN WEST AND NORTH OF THE ILM CWA
DURING THIS PERIOD. AS FOR TEMPS AND HUMIDITY...THE FA WILL BE
LOOKING AT A WEEKEND WITH TEMPS RUNNING 5 TO AS MUCH AS 10 DEGREES
BELOW NORMAL...ESPECIALLY WITH NIGHTTIME LOWS. IN ADDITION...THE
AIRMASS WILL BE ON THE DRY SIDE THIS WEEKEND...WITH PROGGED
SOUNDINGS INDICATING PWS AROUND 1/2 INCH SATURDAY...AND BETWEEN 0.5
TO LESS THAN 1 INCH ON SUNDAY. THE EAST-SOUTHEAST LOW LEVEL FLOW ON
SUNDAY...MAY BRING ENOUGH LOW LEVEL MOISTURE ACROSS THE FA TO
PRODUCE DIURNALLY DRIVEN CU DURING SUNDAY.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 200 AM FRIDAY...THE STRENGTH OF THE UPPER RIDGING EXTENDING FROM
THE UPPER HIGH OVER THE SE STATES...WILL PEAK MONDAY INTO TUESDAY.
THERE-AFTER...MODELS ONLY DRIFT THE NORTH TO SOUTH UPPER RIDGE AXIS
ACROSS AND JUST EAST OF THE FA BY LATE TUE THRU THU. MODELS ARE
DISSIMILAR WITH THE STRENGTH OF THE UPPER LOW WELL OFFSHORE AND/OR
ACROSS THE HIGH SEAS OF THE ATLANTIC OCEAN...AND ITS MOVEMENT
WESTWARD TOWARD THE U.S. MAINLAND. THIS COULD TEMPORARILY PREVENT
THE UPPER RIDGE AXIS FROM PROGRESSING OFF THE EAST COAST. BUT FOR
NOW...WILL CONTINUE WITH THE THEME OF THE UPPER RIDGE AXIS OFF THE
EAST COAST AND THUS ALLOWING SW FLOW ALOFT TO OVERTAKE THE FA WITH
INCREASING MOISTURE AND WARMING TEMPS IN THE LOW LEVELS AS THE
STRENGTH OF THE SFC HIGH ACROSS THE FA DECREASES BUT NEVERTHELESS
CONTINUES TO RIDGE BACK WESTWARD ACROSS PORTIONS OF THE FA.

OVERALL...WILL BE LOOKING AT WARMER TEMPS AND INCREASING MOISTURE
EACH DAY WITH THE THREAT OF PCPN FROM MAINLY DIURNALLY DRIVEN
CONVECTION...WITH THE DAILY BUT SHALLOW SEA BREEZE SUPPLYING ENOUGH
SFC CONVERGENCE AND DYNAMICS TO GET THINGS STARTED. FOR NOW WILL
INDICATE POPS IN THE LOW CHANCE...WITH GFS MOS GUIDANCE ALSO
CONCURRING.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...LOW PRESSURE HAS MOVED FAIRLY RAPIDLY TO THE NORTHEAST
AND OUT OF THE REGION...REPLACED WITH WEAK HIGH PRESSURE. THE COLD
FRONT IS SOUTH OF THE REGION WITH NORTHERLY WINDS AROUND THE HIGH
EXPECTED. TIME HEIGHT SHOWS SOME MID LEVEL MOISTURE LINGERING
THROUGH THE MORNING HOURS...WITH SCATTERED SKIES EXPECTED THIS
AFTERNOON THROUGH THE END OF THE FORECAST PERIOD. MOISTURE PROFILES
ARE TOO DRY TO SUPPORT FOG OVERNIGHT.

EXTENDED OUTLOOK...VFR. MORNING FOG POSSIBLE MONDAY AND TUESDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 600 AM FRIDAY...A SMALL CRAFT SHOULD EXERCISE CAUTION
HEADLINE REMAINS VALID THIS MORNING...EXCEPT FOR THE SEGMENT FROM
LITTLE RIVER INLET TO MURRELLS INLET. A NORTHERLY SURGE IS
UNDERWAY IN THE WAKE OF A COLD FRONT WITH WINDS FROM THE NNE
AROUND 20 KT AND SEAS OF 4 TO 5 FT. A FEW GUSTS TO 25 KT ARE
EXPECTED THIS MORNING. SEAS WILL BE LOWER WHERE A NNE FETCH IS
SEVERELY LIMITED.

THE SURGE WILL BE BRIEF AND LATE THIS MORNING AND THIS AFTERNOON...
WINDS AND SEAS WILL BE ON A STEADY DECLINE. DURING THE AFTERNOON
AND EVE...NE WINDS WILL DIMINISH TO 10 KT OR LESS. A SLIGHT
REINFORCEMENT OF THE MUCH DRIER AND COOLER AIR TONIGHT SHOULD
ALLOW NE WINDS TO INCREASE TO 10 TO 15 KT LATE. SEAS WILL
RESPOND...SUBSIDING TO AROUND 2 FT DURING THE AFTERNOON AND EVE
AND THEN BUILDING ABOUT A FOOT LATE TONIGHT.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 200 AM FRIDAY...COULD SEE A BRIEF CAA SURGE EARLY
SATURDAY...RESULTING WITH HIER WINDS AT 10 TO POSSIBLY 20+ KT.
COULD SEE BRIEF SCEC OR EVEN SCA CONDITIONS. THIS WILL BE FOLLOWED
BY THE SFC HIGHS 1030+ MB CENTER PROGGED TO MOVE OFF THE MID-
ATLANTIC COAST BY LATE SATURDAY...TO WELL OFFSHORE DURING SUNDAY.
WHILE AT THE SAME TIME...CONTINUING TO RIDGE WESTWARD BACK ACROSS
PORTIONS OF THE AREA WATERS. THIS WILL MAKE THE WIND DIRECTION
FORECAST A BIT TRICKY BASED ON THE POSITIONING OF THIS SFC RIDGE
AXIS ACROSS THE LOCAL WATERS. AT THIS POINT...LOOKING AT AN
ONSHORE FLOW DIRECTION THRU THIS PERIOD. A DECENT FETCH SHAPES UP
WHEN THE CENTER OF THE SFC HIGH MOVES OFFSHORE FROM THE MID-
ATLANTIC COAST. WILL LIKELY SEE THE INFLUENCE OF AN INCREASING
E-SE GROUND SWELL ACROSS THE AREA WATERS BY LATE SUNDAY AND
CONTINUING BEYOND. COULD RIP ACTIVITY INCREASE ACROSS AREA
BEACHES...ESPECIALLY LATE IN THIS PERIOD.

LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 200 AM FRIDAY...SFC RIDGING FROM THE RETREATING SFC HIGH TO THE
HIGH SEAS OF THE ATLANTIC...TO CONTINUE TO EXTEND ACROSS THE FA.
THIS WILL KEEP MAINLY AN ONSHORE TRAJECTORY TO THE SFC WIND FIELD. A
POSSIBLE NEW PLAYER TO THE MARINE FORECAST COMES IN THE FORM OF A
WEAK TO MODEST UPPER LOW AND ITS SFC LOW COUNTERPART...MOVING
WESTWARD ACROSS THE ATLANTIC HIGH SEAS. THIS COULD THROW A WRINKLE
IN THE EXTENDED FORECAST DEPENDING HOW CLOSE IT COMES TO THE LOCAL
WATERS DURING THE LATER PERIODS. RIGHT NOW...WILL INDICATE AN
INCREASE TO THE SIGNIFICANT SEAS DUE THIS BUILDING E-SE GROUND
SWELL. WILL KEEP BOTH WINDS/SIGNIFICANT SEAS JUST BELOW SCEC/SCA
CRITERIA BUT LIKELY WILL HIGHLIGHT ITS POSSIBILITY IN THE HAZARDOUS
WX OUTLOOK.

&&

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

&&

$$

NEAR TERM...RJD
SHORT TERM...DCH
LONG TERM...DCH
AVIATION...43


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