238  
FXUS62 KILM 200718  
AFDILM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON NC  
318 AM EDT SAT OCT 20 2018  
   
SYNOPSIS
 
 
WARM AND MOIST AIR WILL RETURN TODAY WITH INCREASING CLOUDS AND  
A CHANCE OF SHOWERS AHEAD OF AN APPROACHING COLD FRONT. THE  
COLD FRONT WILL MOVE THROUGH THE AREA TONIGHT FOLLOWED BY  
CANADIAN HIGH PRESSURE SUNDAY, BRINGING BELOW NORMAL  
TEMPERATURES TO THE REGION THROUGH NEXT WEEK. CHANCES FOR RAIN  
RETURN LATE NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 3 AM SATURDAY...PRE-FRONTAL WARM ADVECTION WILL LEAD TO WEAK  
ISENTROPIC UPGLIDE THAT WILL INCREASE CLOUD COVER AREA-WIDE THROUGH  
MIDDAY SATURDAY. OTHER THAN A GLANCING COASTAL SHOT AT A LITTLE  
LIGHT RAIN MOST PRECIP APPEAR TO STAY OFFSHORE. RAIN CHANCES THEN  
SHIFT TO INLAND ZONES AS COLD FRONT AND HEIGHT FALLS IMPINGE UPON  
THE AREA. THESE HEIGHT FALLS ARE WEAK AS ARE THE EMBEDDED VORTICITY  
CENTERS SO RAIN CHANCES WILL STAY CAPPED IN THE CHANCE RANGE AND QPF  
PROSPECTS ARE QUITE LOW. DEEP LAYER MOISTURE MOVES OFF THE COAST BY  
EVENING AND THE COLD ADVECTION STARTS INTENSIFYING SOON THEREAFTER  
BY ABOUT 03Z. THE COLD ADVECTION IN THE PRESENCE OF A CONTINUED  
MODERATE GRADIENT SHOULD MAKE FOR A BREEZY SATURDAY NIGHT AS WIND  
FIELDS REMAIN ALIGNED THROUGH A DEPTH OF ABOUT 4KFT. AHEAD OF THE  
BOUNDARY THIS AFTERNOON WILL WARM TO NEAR 80 IN MOST PLACES. IN THE  
CAA REGIME TONIGHT TEMPS WILL DIP INTO THE MID TO UPPER 40S, LIKELY  
FASTER THAN PORTRAYED IN GUIDANCE.  
 

 
   
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
 
 
AS OF 3 AM SATURDAY...DRY THROUGH THE SHORT TERM PERIOD AS COOL  
HIGH PRESSURE BUILDS IN FROM THE WEST BEHIND A DEPARTING COLD  
FRONT. WINDS SLOWLY DECREASE THROUGH THE DAY SUNDAY WITH A SUNNY  
SKY AND HIGH TEMPS ONLY IN THE LWR 60S. CHILLY LOWS TO BEGIN  
MONDAY...UPPER 30S INLAND AND 40S ALONG THE COASTAL ZONES,  
ALTHOUGH LIGHTER WINDS, AS THE HIGH NEARS THE AREA. BEING THE  
STRONGEST WINDS SINCE MICHAEL, IT'S POSSIBLE A FEW DANGLING  
LIMBS, LEANED OR WEAKENED TREES COULD STILL DROP OR TOPPLE.  
 

 
   
LONG TERM /TUESDAY THROUGH FRIDAY/
 
 
AS OF 300 PM FRIDAY...HIGH PRESSURE SETTLING OVER THE CAROLINAS  
ON MON WILL KEEP COOL AND DRY WEATHER WITH TEMPS IN THE MID 60S  
UNDER BRIGHT SUNSHINE. BY TUES THE HIGH WILL SHIFT OFF SHORE AS  
A DRY COLD FRONT APPROACHES FROM THE NW. A BIT OF MOISTURE MAY  
BE DRAWN UP AHEAD OF THIS FRONT WITH SOME CLOUDS AND PCP  
POSSIBLE, MAINLY ALONG THE SC COAST OR OFF SHORE. INLAND AREAS  
FROM I-95 WEST, MAY NOT SEE ANY EFFECTS FROM THIS DRY COLD  
FRONT.  
 
ANOTHER LARGE AREA OF HIGH PRESSURE WILL BUILD BEHIND THE FRONT  
THROUGH MID WEEK WITH A PUSH OF COOLER AND DRIER AIR WED INTO  
THURS. MODELS STILL INDICATING A WEDGE PATTERN SETTING UP FOR  
LATE THURS INTO FRI WITH CLOUDS AND PCP SPREADING NORTHWARD AS  
LOW PRESSURE MOVES ACROSS THE SOUTHEAST. LATEST MODEL RUNS SHOW  
LOW DEEPENING OFF THE SOUTHEAST COAST HEADING INTO NEXT WEEKEND  
WITH A DECENT AMOUNT OF RAINFALL POSSIBLE FRI OR SAT. EXPECT  
LOWS IN THE 40S INLAND AND IN THE 50S ALONG THE COAST THROUGH  
MUCH OF NEXT WEEK. TEMPS WILL BE IN THE 60S INLAND TO CLOSER TO  
70 ALONG THE COAST.  
 

 
   
AVIATION /07Z SATURDAY THROUGH WEDNESDAY/
 
 
AS OF 06Z...CEILINGS OVERSPREADING THE AREA BUT WILL TEND TO REMAIN  
MVFR. SOME GUIDANCE HINTING AT LOWER HEIGHTS BUT HAVE BEEN OVERDONE  
AS OF LATE AND GENERALLY DISCOUNTED. SOME LIGHT SHOWER ACTIVITY WILL  
SPREAD WEST TO EAST ACROSS THE REGION BUT THEY WILL BE LIGHT ENOUGH  
TO HAVE LITTLE TO NO MEANINGFUL EFFECTS ON TAFS. GUSTY NW WINDS THIS  
EVENING WILL USHER IN CLEAR SKIES AS COLD AIR POURS INTO THE AREA.  
 
EXTENDED OUTLOOK...EXTENDED OUTLOOK...COLD FRONT PUSHES THROUGH AREA  
AT END OF TAF PERIOD,DRYING OUT CLOUDS AND REMOVING PRECIP CHANCES.  
CONDITIONS IMPROVE TO VFR SUNDAY THROUGH EARLY NEXT WEEK.  
 

 
   
MARINE
 
 
NEAR TERM /THROUGH TONIGHT/...  
AS OF 3 AM SATURDAY...SOUTHWESTERLY PRE-FRONTAL FLOW REGIME TO  
SEE WIND SPEED AND WAVE HEIGHTS BUILD AS THE APPROACHING FRONT  
TIGHTENS THE GRADIENT. SMALL CRAFT ADVISORY CONDITIONS TO BE MET  
BY THIS EVENING. THIS HEADLINE WILL NOT SUFFICE OVER NC WATERS  
HOWEVER AS ONCE THE FRONT PUSHES THROUGH FORECAST SOUNDINGS SHOW  
THAT THE WARM SSTS SHOULD MIX DOWN GALE FORCE GUSTS DUE TO  
STEEP LOW LEVEL LAPSE RATES BEING MAINTAINED. GALE FORCE GUSTS  
WILL ALSO BE POSSIBLE OVER SC WATERS BUT THEY MAY NOT BE QUITE  
FREQUENT ENOUGH TO JUSTIFY THE WARNING.  
 
SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...  
AS OF 3 AM SATURDAY...GALE FORCE GUSTS CONTINUE SUN MORNING,  
AGAIN MOST FREQUENTLY OVER THE NORTH CAROLINA COASTAL WATERS  
WHERE A GALE WARNING IS IN EFFECT. OCCASIONAL GUSTS TO 40 KT  
NOT OUT OF THE QUESTION AS THE COLD AIR BREAKS OUT OVER THE  
MILDER OCEAN WATERS. THE SLIGHT OFFSHORE TRAJECTORY WILL LIMIT  
SEA-HEIGHT GROWTH OVER THE 0-20 NM WATERS, BUT OUTER PORTIONS  
MAY SEE 6-7 FEET. THE SEA SPECTRUM WILL BE DOMINATED BY NORTH  
WAVES EVERY 6 SECONDS, MAKING FOR STEEP AND TREACHEROUS WAVE  
FACES. WINDS WILL EASE BY SUNDAY AFTERNOON, AS THE CENTER OF THE  
APPROACHING HIGH NEARS THE AREA.  
 
LONG TERM /MONDAY THROUGH WEDNESDAY/...  
AS OF 300 PM FRIDAY...COOL CANADIAN HIGH PRESSURE WILL SETTLE  
OVER THE WATERS ON MON WITH THE CENTER JUST INLAND AND NORTH  
BEFORE SHIFTING FURTHER OFF SHORE THROUGH TUES. A DRY COLD FRONT  
WILL CROSS THE WATER TUES NIGHT WITH ANOTHER LARGE AREA OF HIGH  
PRESSURE BUILDING DOWN THROUGH MID WEEK. THIS WILL PRODUCE  
LIGHT AND MORE VARIABLE AND VEERING WINDS MON INTO TUES, 10 KTS  
OR LESS WITH SEAS LESS THAN 3 FT.  
 
A NORTHERLY SURGE BEHIND COLD FRONT WILL PRODUCE A FAIRLY RAPID  
INCREASE IN WINDS AND SEAS LATE WED INTO WED NIGHT. THE COLD  
AIR RUSHING OVER THE WARMER WATERS WILL KEEP THE MARINE LAYER  
WELL MIXED WITH GUSTY NORTHERLY WINDS WED NIGHT INTO THURS. N-NE  
WINDS WILL INCREASE TO 15 TO 25 KTS WITH SCA CONDITIONS POSSIBLE  
WED NIGHT.  
 

 
   
ILM WATCHES/WARNINGS/ADVISORIES
 
 
SC...NONE.  
NC...BEACH HAZARDS STATEMENT FROM 6 AM EDT THIS MORNING THROUGH  
THIS EVENING FOR NCZ110.  
MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 2 PM EDT  
SUNDAY FOR AMZ254-256.  
GALE WARNING FROM 1 AM TO NOON EDT SUNDAY FOR AMZ250-252.  
 

 
 

 
SYNOPSIS...  
NEAR TERM...III/MBB  
SHORT TERM...MJC/MAS/SRP  
LONG TERM...RGZ  
AVIATION...III/MBB/21  
MARINE...  
 
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