753  
FXUS62 KILM 240131  
AFDILM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON NC  
931 PM EDT SAT JUN 23 2018  
   
SYNOPSIS
 
 
HOT AND HUMID WEATHER WITH ISOLATED THUNDERSTORMS WILL CONTINUE  
THROUGH MONDAY. HEAT ADVISORIES ARE IN EFFECT SUNDAY, AND ARE  
POSSIBLE MONDAY. A COLD FRONT WILL CROSS THE AREA LATE MONDAY  
AND TUESDAY BRINGING A GOOD CHANCE FOR SHOWERS AND THUNDERSTORMS  
AND A RELIEF FROM THE HEAT THROUGH THURSDAY. TEMPERATURES WILL  
REBOUND TO ABOVE NORMAL AGAIN BY NEXT FRIDAY BUT WITH GOOD  
CHANCES FOR SHOWERS AND THUNDERSTORMS.  
 

 
   
NEAR TERM /THROUGH SUNDAY/
 
 
AS OF 930 PM SATURDAY...BUMPED COASTAL WINDS UP IN THE CAPE FEAR  
AREA FOR THE NEXT FEW HOURS AS PIERS AND BEACHES ARE STILL  
SHOWING GUSTS OVER 20 MPH. NO OTHER SIGNIFICANT CHANGES.  
DISCUSSION FROM 700 PM FOLLOWS...  
 
A 300 MB JET STREAK PROBABLY HELPED SUPPORT A MODEST LINE OF  
CONVECTION ACROSS THE CAPE FEAR REGION EARLIER THIS AFTERNOON.  
THIS FEATURE IS NOW OFF THE COAST, AND A CAPPED MARINE AIRMASS  
WASN'T ABLE TO SUPPORT THE STORMS ANYWAY.  
 
A CLUSTER OF SHOWERS AND STORMS ACROSS EASTERN SC IS ALSO DRYING  
UP AS IT APPROACHES THE SANTEE RIVER. I'VE MAINTAINED A 20 POP  
IN THE GEORGETOWN, SC AREA FOR THE NEXT COUPLE OF HOURS,  
OTHERWISE I'M FORECASTING DRY WEATHER OVERNIGHT. A SOUTHWESTERLY  
LOW LEVEL JET SHOULD AGAIN KEEP THE HOT BOUNDARY LAYER MIXED,  
AND SIMILARLY TO LAST NIGHT LOWS SHOULD RANGE FROM 75 DEGREES  
WEST OF I-95 TO AROUND 80 ON THE BEACHES. MINOR EDITS HAVE ALSO  
BEEN MADE TO POPS FOR SUNDAY, DROPPING THEM INTO THE 20-30  
PERCENT RANGE GIVEN THE MAGNITUDE OF DRY AIR ALOFT ANTICIPATED  
TO MOVE ACROSS THE AREA.  
-TRA  
 
DISCUSSION FROM 300 PM FOLLOWS...  
AN MCV SHOULD DRIVE CONVECTION ACROSS EASTERN GEORGIA AND  
SOUTHERN SOUTH CAROLINA THROUGH MID EVE. ONGOING CONVECTION HAS  
BEEN FAIRLY SHALLOW OWING LARGELY TO THE AMOUNT OF DRY AIR IN  
THE MID LEVELS, BUT A FEW STRONG THUNDERSTORMS ARE STILL  
POSSIBLE LATE THIS AFTERNOON ACROSS OUR FA. WILL FOLLOW THE  
GUIDANCE OFFERED BY THE HIGH RESOLUTION MODELS IN KEEPING THE  
CONVECTION MAINLY ISOLATED WITH AN EMPHASIS ACROSS THE CAPE FEAR  
AREA AS A MID- LEVEL SHORTWAVE SKIRTS THE AREA AS IT MOVES OFF  
THE MID-ATLANTIC LATE THIS EVE. WILL ALSO KEEP THE PREVIOUS  
TREND WITH THE RISK FOR CONVECTION DWINDLING WITH LOSS OF  
HEATING AS A MID-LEVEL SHORTWAVE PIVOTS OFFSHORE OF THE MID-  
ATLANTIC STATES. LOWS TONIGHT WILL BE IN THE MUGGY MID AND UPPER  
70S AND A FEW SPOTS WILL STRUGGLE TO GET AS LOW AS 80 DEGREES.  
 
A HEAT ADVISORY IS IN EFFECT FOR SUN WITH HEAT INDEX VALUES MAINLY  
IN THE RANGE OF 105 TO 109 DEGREES. A FEW SPOTTY 110 VALUES ARE  
POSSIBLE. HIGHS WILL BE IN THE MID AND UPPER 90S AND 100 DEGREES IS  
POSSIBLE, ESPECIALLY ACROSS INLAND AREAS. A FLAT 500 MB RIDGE WILL  
PROMOTE SUBSIDENCE AND DOWNSLOPE FLOW WHICH WILL KEEP THE SEABREEZE  
PINNED, ALLOWING EVEN THE BEACHES TO REACH INTO THE LOWER AND MID  
90S. GIVEN THE ABUNDANCE OF HEAT AND HUMIDITY, EXPECT ISOLATED TO  
PERHAPS SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP WITH AN  
EMPHASIS FOR LATER AFTERNOON SUN AND SUN NIGHT AS THE THUNDERSTORMS  
STRUGGLE TO OVERCOME THE DRIER AIR IN THE MID LEVELS. THE PIEDMONT  
TROUGH AND SEABREEZE SHOULD BE AREAS WHERE CONVECTION INITIATES.  
 

 
   
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
 
 
AS OF 300 PM SATURDAY...BERMUDA HIGH AND FLATTENING MID-LEVEL RIDGE  
WILL HOLD ON INTO MON. A MID-LEVEL SHORTWAVE IS EXPECTED TO MOVE  
ACROSS THE AREA SUN NIGHT AND THIS TROUGH WILL HELP PUSH THE  
PIEDMONT TROUGH TO THE COAST. STRONGER UPPER LEVEL SUPPORT IS  
EXPECTED TO ARRIVE LATE MON AND MON NIGHT. A COLD FRONT WILL SLOWLY  
SAG S AND SHOULD MOVE INTO THE FA MON NIGHT AND IT IS POSSIBLE IT  
WILL BE AS FAR SOUTH AS THE SOUTH SANTEE RIVER DURING THE EARLY  
MORNING HOURS OF TUE AS A 500 MB TROUGH EXITS THE NORTHEAST STATES.  
 
PRECIPITABLE WATER VALUES ARE FORECAST TO BE NEAR OR IN EXCESS OF  
2.25 INCHES SUN NIGHT AND MON AND INSTABILITY IS EXPECTED TO BE HIGH  
WITH MIXED LAYER CAPE VALUES IN EXCESS OF 3000 J/KG. FOR THIS  
REASON, WE HAVE RAISED POPS TO THE LIKELY CATEGORY MON AND MON NIGHT  
AND SHOW POPS TRENDING HIGHER SUN NIGHT AS A CLUSTER OF  
THUNDERSTORMS SHOULD REACH THE AREA DURING THE EVE. POPS MAY NEED TO  
BE BOOSTED WITH LATER ISSUANCES AS TIMING DETAILS ARE IRONED OUT  
GIVEN THE INGREDIENTS FOR A WIDESPREAD AND PERHAPS SIGNIFICANT  
RAINFALL EVENT SEEM TO BE COMING TOGETHER.  
 
CLOUDS AND CONVECTION MON SHOULD ALLOW TEMPS TO BACK OFF AS  
COMPARED TO SUN AND WE ARE CURRENTLY FORECASTING MAINLY LOWER AND  
MID 90S. HOWEVER, GIVEN THE HIGH DEWPOINTS, AT LEAST SOME OF THE  
AREA MAY AGAIN REQUIRE A HEAT ADVISORY. LOWS SUN NIGHT WILL BE IN  
THE MID AND UPPER 70S. LOWS MON NIGHT SHOULD BE SLIGHTLY LOWER,  
MAINLY MID 70S WITH PERHAPS A FEW LOWER 70S IN RAIN COOLED  
ENVIRONMENT.  
 

 
   
LONG TERM /TUESDAY THROUGH SATURDAY/
 
 
AS OF 300 PM SATURDAY...COLD FRONT WILL BE MEANDERING TO THE SOUTH  
EARLY ON TUESDAY BEFORE WASHING OUT CLOSER TO THE GULF COAST ON  
WEDNESDAY. THIS WILL BRING A REPRIEVE FROM THE HEAT AND HUMIDITY,  
BUT WILL ALSO FEATURE GOOD SHOWER AND TSTM CHANCES, ESPECIALLY  
TUESDAY DURING FROPA. THIS FRONT WILL BE FOLLOWED BY CANADIAN HIGH  
PRESSURE BRINGING MUCH COOLER TEMPERATURES AND LOWER HUMIDITY DURING  
WEDNESDAY. THIS WILL ALSO BRING LOWER CONVECTIVE POTENTIAL  
WEDNESDAY, AND CONTINUING INTO THURSDAY AS THE HIGH BEGINS TO  
REBUILD BOTH AT THE SURFACE AND ALOFT. THURSDAY IS INTERESTING  
BECAUSE THE GUIDANCE SHOWS A WEAK SURFACE LOW TRYING TO DEVELOP  
ALONG A REMNANT TROUGH JUST OFFSHORE IN RESPONSE TO PVA ASSOCIATED  
WITH ONE FINAL SHORTWAVE DRIFTING ACROSS THE SE. WHILE LOW PRESSURE  
DEVELOPMENT SEEMS PLAUSIBLE, MOST OF THE PRECIP WILL LIKELY REMAIN  
OFFSHORE AND WILL KEEP POP LOW THURSDAY DESPITE THIS DEVELOPMENT.  
 
THIS RIDGE WILL EXPAND ACROSS THE EASTERN CONUS INTO NEXT WEEKEND,  
BUT THE ORIENTATION IS PROGGED TO DRIVE THE HIGHEST HEAT TO OUR  
NORTH, KEEPING THE CAROLINAS WARM AND HUMID BUT UNSETTLED AS ONSHORE  
FLOW BECOMES ENTRENCHED AND PWATS CLIMB TO WELL ABOVE 2 INCHES  
AGAIN. WILL SHOW TEMPS CLIMBING BACK TO ABOVE NORMAL ALONG WITH  
ABOVE CLIMO PRECIP CHANCES FRIDAY AND SATURDAY.  
 

 
   
AVIATION /00Z SUNDAY THROUGH THURSDAY/
 
 
AS OF 00Z...VFR CONDITIONS SHOULD CONTINUE THROUGH AT LEAST 16Z  
ON SUNDAY, BEFORE ISOLATED SHOWERS AND T-STORMS DEVELOP DURING  
THE HEAT OF THE DAY. COVERAGE SHOULD AVERAGE ONLY 20-30 PERCENT  
DURING THE 16-23Z TIMEFRAME. SOUTHWEST SURFACE WINDS COULD  
EXCEED 15 KNOTS ALONG THE COAST WITH SUNDAY AFTERNOON'S  
SEABREEZE.  
 
EXTENDED OUTLOOK...MOSTLY VFR. MAINLY AFTERNOON SHOWERS AND  
THUNDERSTORMS EACH DAY WITH SHORT DURATION FLIGHT CATEGORY  
RESTRICTIONS POSSIBLE. A COLD FRONT WILL BRING A HIGHER  
PROBABILITY FOR SHOWERS AND THUNDERSTORMS MONDAY INTO TUESDAY.  
 

 
   
MARINE
 
 
NEAR TERM /THROUGH SUNDAY/...  
AS OF 930 PM SATURDAY...I'VE RAISED AN 'EXERCISE CAUTION'  
HEADLINE ON THE COASTAL WATERS FROM MYRTLE BEACH NORTHWARD  
THROUGH CAPE FEAR AND SURF CITY THROUGH 3 AM SUNDAY. THIS IS  
DUE TO SEAS RESPONDING STRONGLY TO THE SW 15-20 KNOT WINDS.  
SEAS WERE RECENTLY REPORTED UP TO 5 FEET AT THE CORMP 'HARBOR'  
BUOY JUST SOUTH OF SOUTHPORT. THE POTENTIAL FOR 4-5 FOOT SEAS  
SHOULD BE WITH US MOST OF THE NIGHT, DIMINISHING LATE AS WIND  
SPEEDS DIMINISH SLIGHTLY. DISCUSSION FROM 700 PM FOLLOWS...  
 
BREEZY WINDS GUSTING UP TO 25 KNOTS ACROSS THE ENTIRE MARINE  
AREA SHOULD CONTINUE OVERNIGHT AWAY FROM SHORE EVEN AFTER THE  
SEABREEZE DIES AWAY. LATEST BUOY REPORTS AGREE CLOSELY WITH OUR  
FORECAST SEA HEIGHTS, AND NO SIGNIFICANT CHANGES ARE BEING MADE  
TO THE FORECAST WITH THIS EARLY EVENING UPDATE. DISCUSSION FROM  
300 PM FOLLOWS...  
 
NOCTURNAL JETTING ON THE ORDER OF 30 KT AT 1500 FT WILL KEEP  
WINDS ELEVATED TONIGHT, MAINLY 15 TO 20 KT. A ROBUST SEABREEZE  
CIRCULATION AND INLAND TROUGH WILL ALLOW WINDS TO PEAK IN THE 15  
TO 20 KT RANGE DURING THE AFTERNOON. SEAS WILL BE 3 TO 4 FT  
WITH A FEW 5 FT SEAS POSSIBLE ACROSS THE OUTERMOST WATERS.  
 
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...  
AS OF 300 PM SATURDAY...SW WINDS WILL DOMINATE SUN AND THROUGH MON  
EVE WITH WINDS THEN SHIFTING TO NE AND NNE LATE MON NIGHT AND TUE  
MORNING IN THE WAKE OF A COLD FRONT SAGGING ACROSS THE WATERS FROM N  
TO S. WIND SPEEDS WILL BE MAINLY 15 TO 20 KT SUN NIGHT WITH  
NOCTURNAL JETTING IN PLACE. WIND SPEEDS MON SHOULD BE SLIGHTLY  
LOWER, MAINLY 10 TO 15 KT. WIND SPEEDS WILL LOWER TO 10 KT OR LESS  
LATE MON NIGHT. SEAS WILL BE 3 TO 4 FT SUN NIGHT WITH PERHAPS SOME 5  
FT SEAS OBSERVED, MAINLY ACROSS THE OUTERMOST WATERS. SEAS ON MON  
SHOULD BE CLOSER TO 3 FT WITH 2 TO 3 FT SEAS CURRENTLY FORECAST LATE  
MON NIGHT. OF COURSE WINDS AND SEAS WILL BE STRONGER IN  
THUNDERSTORMS WHICH WILL BE NUMEROUS, ESPECIALLY MON NIGHT.  
 
LONG TERM /TUESDAY THROUGH THURSDAY/...  
AS OF 300 PM SATURDAY...NE WINDS WILL SURGE BEHIND A COLD FRONT  
TUESDAY TO 10-15 KTS BEFORE VEERING SLOWLY TO THE EAST THROUGH  
NIGHTFALL. HIGH PRESSURE WILL RIDGE INTO THE REGION WEDNESDAY BUT  
MAINTAIN ITS RIDGE AXIS TO THE NORTH. THIS WILL KEEP WINDS FROM THE  
E ON WEDNESDAY BEFORE THE HIGH PUSHES AWAY TURNING WINDS TO THE S AT  
THE END OF THE PERIOD. WIND SPEEDS WED/THU WILL BE AROUND 10 KTS.  
WAVE HEIGHTS WILL BE GENERALLY 2-4 FT THROUGH THE PERIOD, WITH A NE  
WIND WAVE GIVING WAY TO A E/SE WIND WAVE AND SWELL LATER IN THE  
WEEK.  
 

 
   
ILM WATCHES/WARNINGS/ADVISORIES
 
 
SC...HEAT ADVISORY FROM 11 AM TO 8 PM EDT SUNDAY FOR SCZ017-023-024-  
032-033-039-054>056-058-059.  
BEACH HAZARDS STATEMENT FROM 6 AM EDT SUNDAY THROUGH SUNDAY  
EVENING FOR SCZ054-056.  
NC...HEAT ADVISORY FROM 11 AM TO 8 PM EDT SUNDAY FOR NCZ087-096-099-  
105>110.  
BEACH HAZARDS STATEMENT FROM 6 AM EDT SUNDAY THROUGH SUNDAY  
EVENING FOR NCZ106-108.  
MARINE...NONE.  
 

 
 

 
 
SYNOPSIS...JDW  
NEAR TERM...RJD/TRA  
SHORT TERM...RJD  
LONG TERM...JDW  
AVIATION...TRA  
 
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