594
FXUS62 KILM 150538
AFDILM
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
138 AM EDT SUN SEP 15 2019
SYNOPSIS
A COLD FRONT WILL MEANDER AROUND THE AREA FOR THE NEXT SEVERAL
DAYS. HIGH PRESSURE WILL BUILD IN FROM THE NORTHEAST DURING THIS
TIME AS THE FRONT GRADUALLY DISSIPATES. HUMBERTO WILL REMAIN
WELL OFFSHORE WITH THE ONLY IMPACTS LOCALLY BEING AN INCREASED
THREAT FOR STRONG RIP CURRENTS.
UPDATE
CHANGES SCANT, SHAVED A FEW POINTS OFF PROBABILITY OF MEASURABLE
RAINFALL TO BELOW 25 PERCENT, INTO ISOLATED RANGE, SHOWERS OFF
THE SEA. NO OTHER AMENDMENTS APPLIED, ONLY TYPICAL, TINY, T/TD
REFINEMENTS. DARN DECENT MIDDLE SEPTEMBER SATURDAY EVENING ON
TAP FOR OUR CORNER OF THE GLOBE.
NEAR TERM /THROUGH MONDAY/
LATEST SFC ANALYSIS SHOWS A WEAK FRONTAL BOUNDARY OVER THE AREA,
1030 MB HIGH PRESSURE WELL OFF TO THE NE, AND TROPICAL STORM
HUMBERTO NEAR THE NORTHERN BAHAMAS. HUMBERTO IS NOT EXPECTED TO HAVE
ANY DIRECT IMPACTS OVER THE LOCAL AREA ASIDE FROM INCREASING SWELL
AND RIP THREAT. ONSHORE FLOW AND RESULTING WEAK CONVERGENCE ALONG
THE WEAK FRONT HAS LED TO ISOLATED/WIDELY SCATTERED WEAK CONVECTION
NEAR THE COAST THUS FAR THIS AFTN, WHICH WILL CONTINUE INTO THE
EVENING BEFORE DISSIPATING OVERNIGHT. NOT EXPECTING AS MUCH COVERAGE
AS YESTERDAY, AND FAR INLAND AREAS SHOULD STAY DRY. NIGHTTIME
LANDBREEZE COULD KEEP SOME SHRAS AROUND OVERNIGHT OVER THE
WTRS...HELD ONTO A 20% CHANCE OF RAIN THERE ALL NIGHT. LOW TEMPS IN
THE LOW/MID 70S TONIGHT.
POPS AGAIN IN THE 20-30% RANGE FOR SUNDAY, HIGHEST NEAR THE COAST.
INLAND AREAS AGAIN EXPECTED TO BE DRY DUE TO SUBSIDENCE FARTHER AWAY
FROM HUMBERTO. ONLY LIGHT PRECIP AMOUNTS EXPECTED WITH JUST A SLIGHT
CHANCE OF THUNDER. HIGH TEMPS IN THE LOW/MID 80S DUE TO ENE FLOW.
HUMBERTO STAYS WELL OFF TO THE SOUTH INTO SUNDAY NIGHT, WITH THE
HIGHEST RAIN CHANCES AGAIN OFFSHORE (30-40% POPS). LOW TEMPS MAINLY
IN THE LWR 70S.
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/
HUMBERTO WILL BE WELL OFF THE SOUTHEAST COAST MON MORNING,
TRACKING EAST, AWAY FROM THE REGION. INCREASING SUBSIDENCE
AROUND THE PERIPHERY OF THE STORM AND AN ABUNDANCE OF MID-LEVEL
DRY AIR SUGGEST MON COULD END UP A GOOD BIT DRIER THAN
PREVIOUSLY EXPECTED. WILL TREND RAINFALL CHANCES DOWNWARD, BUT
FURTHER REDUCTION MAY BE NEEDED WITH SUBSEQUENT UPDATES. CLOUD
COVER MAY NOT BE AS WIDESPREAD AS PREVIOUSLY THOUGHT, WITH
TEMPERATURES A LITTLE WARMER MON AFTERNOON.
EXIT OF HUMBERTO MON NIGHT INTO TUE HELPS DRIVE A COLD FRONT
INTO THE AREA FROM THE NORTH. LOW LEVEL MOISTURE INCREASES WITH
THE ARRIVAL OF THE FRONT, BUT ALOFT DEEP DRY AIR AND SUBSIDENCE
WILL PERSIST. CLOUD COVER IS LIKELY TO INCREASE ON TUE, BUT THE
SHALLOW NATURE OF THE MOISTURE WILL KEEP SHOWER AND THUNDERSTORM
CHANCES ON THE LOW SIDE. TEMPERATURES ABOVE CLIMO ONCE AGAIN
TUE WITH INLAND AREAS RUNNING SEVERAL DEGREES ABOVE CLIMO.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
MID-LEVEL RIDGING OVER THE LOWER MISSISSIPPI VALLEY WILL GRADUALLY
EXPAND EAST LATE NEXT WEEK. AT THE SURFACE HIGH PRESSURE WILL BUILD
IN FROM THE NORTHEAST, SETTING UP AN EARLY SEASON WEDGE PATTERN. AT
FIRST LOW LEVEL DRY AIR WILL KEEP SKIES MOSTLY CLEAR AND LIMIT
RAINFALL CHANCES. PROLONGED PERIOD OF NORTHEAST FLOW WILL LEAD TO
INCREASING LOW LEVEL MOISTURE LATE IN THE WEEK, INCREASING CLOUD
COVER AS WELL AS SHOWER AND THUNDERSTORM CHANCES.
-LOW RAINFALL CHANCES WED AND THU DUE TO DEEP DRY AIR AND SUBSIDENCE.
-INCREASING MOISTURE FRI AND SAT WILL INCREASE RAINFALL CHANCES
LATE IN THE WEEK.
-NORTHEAST FLOW WILL KEEP TEMPS A LITTLE BELOW CLIMO WED/THU.
NEAR CLIMO TEMPS EXPECTED FRI/SAT AS AIRMASS MODIFIES.
AVIATION /06Z SUNDAY THROUGH THURSDAY/
THERE ARE SOME POCKETS OF MVFR CIGS AROUND ONCE AGAIN THIS
MORNING MORESO ALONG THE COAST. CONTINUED TO TREND DOWN TO A
COUPLE OF HOURS OF IFR ONCE AGAIN MAINLY ALONG THE COAST. FOR
LATER TODAY BASICALLY PERSISTENCE CONDITIONS WITH A FEW SHOWERS
POSSIBLE WARRANTING ONLY VCSH UNDER VFR CONDITIONS.
EXTENDED...PREDOMINANTLY VFR CONDITIONS, EXCEPT FOR POSSIBLE
FOG AND/OR LOW STRATUS IN THE EARLY MORNING HOURS.
MARINE
MAIN STORY OVER THE WTRS THIS WEEKEND WILL BE INCREASING SWELL DUE
TO TROPICAL STORM HUMBERTO. GUIDANCE IS ALREADY RUNNING ABOUT A FOOT
TOO LOW AT MANY OF THE AREA BUOYS. ALTHOUGH HUMBERTO IS EXPECTED TO
STAY WELL OFFSHORE, 8-9 SECOND SWELL WILL INCREASE TO 4-6 FT BY
SUNDAY. A SMALL CRAFT ADVISORY HAS THEREFORE BEEN ISSUED SUNDAY
MORNING THROUGH THE END OF THE 4TH PERIOD (MONDAY), AND POTENTIALLY
MAY NEED TO BE EXTENDED IN FUTURE FORECAST UPDATES. WINDS WILL
AVERAGE OUT OF THE ENE AT 10-20 KT THIS WEEKEND, WITH STRONG HIGH
PRESSURE OFF TO THE NE.
COMBINATION OF PINCHED GRADIENT BETWEEN HUMBERTO AND HIGH PRESSURE
TO THE NORTH COUPLED WITH SWELL FROM HUMBERTO IS LIKELY TO CREATE
CONDITIONS AT OR ABOVE SMALL CRAFT ADVISORY THRESHOLDS FOR MUCH OF
NEXT WEEK. MARGINAL SCA CONDITIONS PRESENT MON MORNING, BUT BY
MIDDAY SOLID SCA CONDITIONS EXPECTED FOR ALL WATERS. NORTHEAST FLOW
WILL REMAIN 15 TO 20 KT THROUGH THU WITH PERIODS OF SOLID 20 KT FLOW
AT TIMES. SEAS, RUNNING BETWEEN 4 AND 7 FT, WILL BE A MIX OF AN
INCREASING EAST-NORTHEAST WIND WAVE AND A SOUTHEAST SWELL.
ILM WATCHES/WARNINGS/ADVISORIES
SC...HIGH RIP CURRENT RISK FROM 6 AM EDT THIS MORNING THROUGH THIS
EVENING FOR SCZ054-056.
BEACH HAZARDS STATEMENT FROM 6 AM EDT THIS MORNING THROUGH
THIS EVENING FOR SCZ056.
NC...HIGH RIP CURRENT RISK FROM 6 AM EDT THIS MORNING THROUGH THIS
EVENING FOR NCZ106-108-110.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 6 PM EDT
MONDAY FOR AMZ250-252-254-256.
SYNOPSIS...08
UPDATE...08
NEAR TERM...MAS
SHORT TERM...III
LONG TERM...III
AVIATION...SHK
MARINE...III/MAS
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