Area Forecast Discussion
Issued by NWS Wilmington, NC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KILM 301855
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
255 PM EDT SAT MAY 30 2015

.SYNOPSIS...
HIGH PRESSURE CENTERED WELL OFF THE EAST COAST WILL SLOWLY LOSE
ITS INFLUENCE THROUGH MONDAY. A COLD FRONT WILL APPROACH FROM THE
NORTH EARLY NEXT WEEK AND WILL BE IN CLOSE PROXIMITY MID AND LATE
NEXT WEEK. THERE IS A RISK FOR SHOWERS AND THUNDERSTORMS EACH
DAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 200 PM SATURDAY...SYNOPTIC PATTERN REMAINS ONE THAT CAN BE
BEST DESCRIBED AS A "HYBRID SUMMER TYPE SETUP" THANKS TO THE
PERSISTENT HIGH PRESSURE OFFSHORE BEING WELL DISPLACED FROM THE MORE
TYPICAL BERMUDA RIDGE SETUP. WHILE THE NORMAL SETUP IN THE DOLDRUMS
OF SUMMER WOULD HAVE THE HIGH CENTER MUCH FURTHER SW THAN WHERE IT
CURRENTLY RESIDES...THE PATTERN IS BASICALLY THE SAME...WITH THE
MAJOR DIFFERENCE BEING THE AIRMASS ADVECTING INTO THE REGION. AS HAS
BEEN DISCUSSED PREVIOUSLY...AIR PARCELS MOVING INTO THE CAROLINAS
ACTUALLY HAVE ORIGINATED IN SOUTHERN CANADA AND HAVE MADE THE 8 DAY
TRANS-ATLANTIC TRIP AROUND THE SURFACE HIGH BEFORE REACHING THIS
AREA. THIS IS CLEARLY EVIDENT ON HYSPLIT BACK TRAJECTORIES...AND
THIS MODIFIED CONTINENTAL AIRMASS CARRIES MUCH LESS MOISTURE THAN
THE TYPICAL SUB-TROPICAL AIRMASS ENCOUNTERED DURING THE SUMMER. IT
IS PRIMARILY THIS REASON THAT SHOWERS/CONVECTION HAVE BEEN ONLY
ISOLATED IN NATURE.

THAT BEING SAID...LONG RESIDENCE TIMES OVER THE OPEN OCEAN STILL
TRANSPORT MOISTURE LOCALLY...AND ISOLATED SHOWERS HAVE DEVELOPED
ACROSS THE AREA...AND WILL CONTINUE TO DO SO THROUGH NIGHTFALL. THE
BEST CHANCE FOR THIS WILL BE THE CENTRAL PORTIONS OF THE CWA WEST OF
THE RESULTANT...AS WELL AS ALONG THE SEA BREEZE "NOTCH" WHICH WILL
BE ORIENTED SE TO NW ACROSS BRUNSWICK AND COLUMBUS COUNTIES. HAVE
CARRIED ONLY THE ISOLATED WORDING IN THE WX GRIDS...AND DO NOT HAVE
ANY LIGHTNING AS DRY AIR ALOFT WILL SUPPRESS ANY UPDRAFTS FROM
REACHING CHARGE SEPARATION TEMPERATURES.

SHOWER ACTIVITY WILL WANE AFTER DARK WITH LOSS OF HEATING...BUT
RENEWED SHOWER ACTIVITY MAY ONCE AGAIN DEVELOP OFFSHORE AND ADVECT
TOWARDS THE COAST. HAVE KEPT MENTIONABLE POP JUST EAST OF THE CAPE
FEAR REGION...BUT WOULD NOT BE SURPRISED IF A FEW SHOWERS AGAIN
REACH THE SHORE FROM CAPE FEAR NORTH BY SUNRISE. THE OTHER CONCERN
TONIGHT WILL BE FOG POTENTIAL. MOS NUMBERS ARE HIGHLY VARIABLE...BUT
MINS HAVE BEEN COOLER THAN FORECAST THE PAST FEW NIGHTS. HAVE SIDED
WITH THE COOLER MET NUMBERS AGAIN TONIGHT WITH LOW 60S INLAND AND
MID 60S AT THE COAST. THIS IS IMPORTANT BECAUSE CROSSOVER
TEMPERATURES ARE FORECAST TO BE REACHED IN SOME LOCATIONS...AND THE
LOCAL UPS FOG PROCEDURE USING THE MODIFIED RICHARDSON NUMBER DOES
PRODUCE A LARGE AREA OF FOG LOCALLY. HAVE OPTED TO KEEP FOG OUT OF
THE OFFICIAL FORECAST (NOT EXPECTING 2SM VSBY) BUT SOME FOG SEEMS
PLAUSIBLE INLAND FROM THE COAST WHERE WINDS WILL GO CALM AND
HYDROLAPSE RATES APPEAR TO SUPPORT AT LEAST SHALLOW FOG.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 200 PM SATURDAY...WESTERN ATLANTIC RIDGE WILL VERY SLOWLY
LOSE ITS INFLUENCE ACROSS THE EASTERN CAROLINAS THROUGH THE
PERIOD. THIS WILL ALLOW A COLD FRONT TO THE NORTH AND NORTHWEST TO
APPROACH AS WE MOVE INTO TUE. PRECIPITABLE WATER VALUES WILL INCREASE
AS DRIER AIR AND SUBSIDENCE ERODE AND WE BEGIN TO TAP GULF OF
MEXICO MOISTURE AHEAD OF APPROACHING TROUGH. INLAND AREAS WILL
EXPERIENCE THE GREATEST SURGE...CLIMBING IN EXCESS OF AN INCH AND
A HALF. STILL NO SIGNIFICANT UPPER LEVEL SUPPORT...ALTHOUGH A
SUBTLE MID-LEVEL DISTURBANCE DOES REACH THE AREA FROM THE WEST
AND NORTHWEST MON AFTERNOON AND EVE.

MIXED LAYER CAPE VALUES WILL RISE TO NEAR 1000 J/KG EACH
AFTERNOON. WE DO EXPECT AN UPTICK IN SHOWER AND THUNDERSTORM
ACTIVITY AND COVERAGE SHOULD BE AT LEAST SCATTERED WITH THE
GREATEST COVERAGE LIKELY MON AFTERNOON AND EVE. AS WAS THE CASE
THIS MORNING...AT LEAST ISOLATED SHOWERS WILL BE POSSIBLE ALONG
THE COAST AS THE SEABREEZE PUSHES INLAND. THE BEACHES WILL BE MORE
PRONE TO GETTING SOME RAINFALL IN THE MORNING WHILE ELSEWHERE POPS
WILL BE HIGHER MIDDAY AND THROUGH THE AFTERNOON AND EVE.

TYPICAL TEMPS FOR THE LAST DAY OF MAY AND JUNE 1ST. HIGHS INLAND
WILL BE IN THE UPPER 80S TO 90 DEGREES. THE SEABREEZE SHOULD KEEP
THE MORE COASTAL LOCATIONS IN THE LOWER 80S. LOWS WILL BE IN THE
UPPER 60S AND LOWER 70S.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
AS OF 200 PM SATURDAY...MEDIUM RANGE GUIDANCE SHOWS A CUTOFF LOW
MEANDERING ACROSS THE GULF COAST INITIALLY WITH A GENERAL
WEAKENING TREND BY THE END OF THE PERIOD. IN TYPICAL SUMMER TIME
PATTERN FORM...THE LOW ESSENTIALLY BECOMES A WEAKNESS IN THE 500MB
HEIGHT PATTERN. AT THE SURFACE...A WEAK COLD FRONT TRUDGES ACROSS
THE CAROLINAS AND ENDS UP OFFSHORE BY SATURDAY. THESE ELEMENTS
WILL COMBINE TO KEEP UNSETTLED CONDITIONS IN THE FORECAST FOR
MOST IF NOT ALL OF THE PERIOD. THE HIGHEST CHANCES OCCUR TUESDAY
AND TREND DOWN SOMEWHAT THEREAFTER. BY THURSDAY THE FORCING
WEAKENS SUFFICIENTLY TO APPLY A MORE ENHANCED DIURNAL TREND TO THE
POPS. WPC IS PAINTING DECENT RAINFALL AMOUNTS ACROSS THE AREA WITH
SEVEN DAY TOTALS RANGING FROM 2-3 INCHES. THE CAVEAT WITH THE
LATEST GUIDANCE IS THE AXIS OF THE HEAVIEST QPF COULD SET UP JUST
OFFSHORE.

REGARDING TEMPERATURES...READINGS...BEYOND A WARMER TUESDAY...WILL
BE NEAR SEASONABLE VALUES WITH HIGHS IN THE LOWER TO MIDDLE 80S AND
OVERNIGHT LOWS IN THE MIDDLE TO UPPER 60S. DEPENDING ON THE ACTUAL
COVERAGE OF CONVECTION...THESE RANGES MAY END UP SOMEWHAT LOWER.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 18Z...SCT TO OCCASIONALLY BKN VFR LEVEL LOW/MID CLOUDS
THIS AFTERNOON...MAINLY INLAND TERMINALS WITH E-SE WINDS. THERE WILL
BE ISOLATED SHOWERS...ESPECIALLY NEAR KILM...ENDING THIS AFTERNOON
BUT BECOMING POSSIBLE AGAIN LATER THIS EVENING. THIS EVENING WINDS
WILL BECOME LIGHT AND VARIABLE. MODELS AGAIN ARE SUGGESTING MVFR
VSBYS DUE TO BR AT THE INLAND TERMINALS. CONFIDENCE OF OCCURRENCE IS
INCREASING...AND HAVE ADDED MVFR PREDOMINANT AT CRE/FLO/LBT. SOME
SHOWERS MAY PRODUCE BRIEF MVFR CIGS AT ILM OVERNIGHT...BUT HAVE
OPTED TO LEAVE THAT OUT OF THE TAF FOR NOW...AND SINCE SHOWER
ACTIVITY SHOULD BE ISOLATED.

EXPECT THE SAME CONDITIONS AFTER SUNRISE WITH TEMPO MVFR CIGS
POSSIBLE BUT VFR FOR THE MOST PART. VCSH CONTINUES AT THE COASTAL
TERMINALS WITH WINDS BECOMING SE AT ALL TERMINALS LATE IN THE TAF
VALID PERIOD.

EXTENDED OUTLOOK...MORNING MVFR CONDITIONS WITH MAINLY AFTERNOON
ISOLATED/SCATTERED SHOWERS AND THUNDERSTORMS THROUGH THE PERIOD. AN
INCREASED CHANCE FOR CONVECTION TUE AND WED. SHOWERS DECREASING FROM
WEST TO EAST THU.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 200 PM SATURDAY...EXPANSIVE HIGH PRESSURE CENTERED WELL NE OF
BERMUDA CONTINUES TO RIDGE BACK TOWARDS THE CAROLINAS THIS AFTN.
THIS RIDGE IS MAINTAINING ITS INFLUENCE ACROSS THE WATERS...CREATING
RATHER BENIGN MARINE CONDITIONS TODAY. WINDS HAVE BEEN PREDOMINANTLY
FROM THE EAST WITH ONLY SLIGHT FLUCTUATION TO SE OR NE...AT SPEEDS
OF LESS THAN 10 KT OUTSIDE OF THE SEA BREEZE. EVEN WITHIN THE
NEAR SHORE SEA BREEZE...WINDS HAVE BEEN 10-15 KT WITH SIMILAR
DIRECTION. WHILE NEAR-SHORE SEAS ARE LIKELY A BIT CHOPPY...THE
PREDOMINANT WAVE GROUP IS FROM A 4FT/9SEC EASTERLY SWELL...DRIVING
SEAS TO 2-4 FT ACROSS THE WATERS. LITTLE CHANGE IN THESE
CONDITIONS IS EXPECTED THROUGH THE PERIOD...THE EXCEPTION BEING
WITHIN THE WATERS IMPACTED BY THE SEA BREEZE WHERE WINDS WILL EASE
WITH LOSS OF HEATING ALLOWING THE MEAN SYNOPTIC WIND TO TAKE OVER
ONCE AGAIN.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 200 PM SATURDAY...WESTERN ATLANTIC HIGH PRESSURE WILL SLOWLY
LOSE ITS GRIP ON THE WATERS. SSE TO S WINDS THROUGH MONDAY WILL
BECOME SW MON NIGHT AS THE RIDGE FINALLY DEPARTS ALLOWING A FRONT
TO APPROACH. WIND SPEEDS DURING THE PERIOD WILL BE NO HIGHER THAN
10 TO 15 KT...SOME HIGHER GUSTS ARE EXPECTED ACROSS THE NEAR SHORE
WATERS DUE TO SEABREEZE INFLUENCES LATE MORNING THROUGH EARLY EVE
EACH DAY. SEAS WILL BE MAINLY 3 TO 4 FT SUN AND SUN NIGHT...BUT
THE 8 TO 9 SECOND EASTERLY SWELL SHOULD CONTINUE TO SLOWLY
ABATE...ALLOWING SEAS TO SUBSIDE ABOUT A FOOT MON AND MON NIGHT.

LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 200 PM SATURDAY...THE LATEST GUIDANCE HAS SHIFTED/DELAYED
THE BACK DOOR FRONTAL PASSAGE UNTIL WEDNESDAY MORNING. FOR
TUESDAY THE ONSHORE SOUTHEAST FLOW OF AROUND TEN KNOTS CONTINUES.
THE AFOREMENTIONED FRONT ALTHOUGH STILL PROGGED TO MOVE ACROSS THE
WATERS...IS WEAKER AND APPEARS TO WASH OUT WITH A BRIEF
NORTHEASTERLY FLOW BECOMING SOUTHEAST AGAIN BY WEDNESDAY EVENING.
WINDS ATTEMPT ANOTHER RUN AT A NORTHEASTERLY DIRECTION THURSDAY
BUT THE SEA BREEZE INFLUENCE SHOULD TRUMP THE WEAKLY FORCED
FRONT. SEAS WILL BE MODEST THROUGH THE PERIOD AT THE MERCY OF
LOWER WIND SPEEDS AND THE CHANGEABLE FETCH. OVERALL EXPECT 1-3
FEET.

&&

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

&&

$$

NEAR TERM...JDW
SHORT TERM...RJD
LONG TERM...SHK
AVIATION...JDW/MRR


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.