336  
FXUS62 KILM 141512  
AFDILM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON NC  
1112 AM EDT TUE AUG 14 2018  
   
SYNOPSIS
 
 
AS A LOW PRESSURE SYSTEM MOVES SLOWLY AWAY, HOTTER AND GENERALLY  
DRIER WEATHER IS EXPECTED TO DEVELOP TUESDAY THROUGH THURSDAY.  
SHOWERS AND THUNDERSTORMS WILL RETURN LATE IN THE WEEK AND INTO  
THE WEEKEND, AS AN APPROACHING UPPER TROUGH BRINGS INCREASING  
MOISTURE INTO THE AREA.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 1030 AM TUESDAY...LOW STRATUS AND FOG HAS FINALLY  
DISSIPATED. A CU FIELD IS NOW FILLING IN WHERE THIS LOW LEVEL  
MOISTURE PREVAILED. TEMPS SHOULD REBOUND RATHER QUICKLY AFTER  
THE SLOW START THIS MORNING, WHICH WAS ALSO THE CASE YESTERDAY  
MORNING. LATEST WATER VAPOR IMAGERY INDICATES WIDESPREAD DRY AIR  
IN THE MID AND UPPER LEVELS. LATEST SOUNDINGS AND RH TIME HEIGHT  
DISPLAYS FOR LOCATIONS ACROSS THE FA INDICATE PLENTY OF LOW  
LEVEL MOISTURE AVBL. HAVE CONTINUED THE LOW POPS FOR CONVECTION  
MAINLY ACROSS THE ILM NC CWA. EXPECTATION IS FOR THIS CONVECTION  
WILL BE ASSOCIATED WITH 1 OF THE LAST VORTS OR SPEED MAXES  
ROTATING AROUND THE UPPER LOW CENTERED OVER PA, THAT MAY  
EXTEND THIS FAR SOUTH. AS A RESULT, CONVECTION POTENTIAL COULD  
OCCUR FOR SEVERAL HRS AFTER SUNSET ACROSS THE ILM NC CWA...ALBEIT  
IT WILL BE A LOW CHANCE. HAVE INDICATED IN THE HWO FOR 30 TO 40  
MPH WIND GUSTS AND PEA SIZE HAIL POSSIBLE FROM THE STRONGER  
TSTORMS. HAVE CUT BACK THE HIGHS BY SEVERAL DEGREES, ESPECIALLY  
OVER THE ILM SC CWA WHERE MID 90S WAS CUT BACK TO THE LOWER  
90S.  
 
PREVIOUS.....................................................  
AS OF 300 AM TUESDAY...COLD FRONT NEARLY STALLED JUST WEST OF THE  
AREA. IT WILL REMAIN MORE OR LESS IN PLACE WHILE BECOMING MORE  
DIFFUSE THROUGH THE NEAR TERM PERIOD. DESPITE THIS THERE WILL STILL  
BE ENOUGH WESTERLY DEEP LAYER FLOW TO CONTINUE TO IMPORT MOISTURE  
OFFSHORE. SHOWERS AND STORM COVERAGE WILL BE RATHER LOW THIS  
AFTERNOON AND LIKELY NEED MORE DAYTIME HEATING THAN PREVIOUS DAYS.  
COASTAL LOCALES WILL BE MOST FAVORED BUT STORMS MAY ALSO BE FOUND  
ACROSS SOME OF THE PEE DEE. THIS IS MOSTLY IN LINE WITH PREVIOUS  
THINKING THOUGH THE GFS HAS NO MEANINGFUL PRECIPITATION ACROSS THE  
AREA AT ALL THROUGH THE PERIOD. INTERESTINGLY THE WRF (WHICH HAS  
BEEN QUITE HOT HANDED LATELY) HAS NONE EITHER THROUGH THE DAYTIME  
HOURS BUT BLOSSOMS SOME CONVECTION ACROSS MAINLY THE PEE DEE AND  
GRANT STRAND AT NIGHT. THIS HASN'T BEEN OCCURRING LATELY (SAVE FOR  
OFFSHORE) BUT GIVEN THE WRF'S RECENT TRACK RECORD SOME POPS HAVE  
BEEN ADDED.  
 

 
   
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
 
 
AS OF 300 AM TUESDAY...IN THE UPPER LEVELS THE SUBTROPICAL RIDGE  
WILL EXTEND FROM BERMUDA WESTWARD ACROSS FLORIDA AND THE GULF  
COAST. THIS WILL PLACE THE CAROLINAS AT THE SOUTHERN EDGE OF THE  
MID-LATITUDE WESTERLIES WHERE A SHORT-AMPLITUDE TROUGH-RIDGE-  
TROUGH PATTERN WILL EXIST ACROSS THE EASTERN U.S. WEDNESDAY.  
 
THE SHORTWAVE RIDGE SHOULD BECOME OUR MOST SIGNIFICANT FEATURE  
ALOFT WEDNESDAY THROUGH THURSDAY, BRINGING DRY MID-LEVEL AIR AND  
SUPPORTING 850 MB TEMPS AROUND +18C. BERMUDA HIGH PRESSURE AT  
THE SURFACE AND A PIEDMONT TROUGH INLAND SHOULD HELP MAINTAIN A  
LIGHT SOUTHWESTERLY WIND. HIGHS SOARING INTO THE 90S SHOULD  
GUARANTEE A WELL-DEFINED SEABREEZE CIRCULATION BOTH DAYS, WITH  
THE SEABREEZE BOUNDARY PLUS THE PIEDMONT TROUGH INLAND LIKELY  
SERVING AS GENESIS POINTS FOR ISOLATED SHOWERS AND STORMS, EVEN  
DESPITE THE VERY DRY CONDITIONS ALOFT. FORECAST POPS ARE ONLY  
20 PERCENT.  
 
THERE ARE NO SIGNIFICANT SYNOPTIC PATTERN DIFFERENCES BETWEEN  
THE ECMWF, NAM, OR GFS, HOWEVER I DID NOTICE THE ECMWF ISN'T  
QUITE AS DRY AS THE OTHER MODELS WITH MID-LEVEL MOISTURE THROUGH  
THE PERIOD.  
 

 
   
LONG TERM /FRIDAY THROUGH MONDAY/
 
 
AS OF 300 PM MONDAY...TYPICAL SUMMERTIME SETUP WILL EVOLVE LATE WEEK  
AS BERMUDA TYPE HIGH PRESSURE SPINS OFFSHORE. ON THURSDAY, RIDGING  
ALOFT WILL CAP MOST CONVECTION DESPITE SLOWLY INCREASING COLUMN  
MOISTURE. HOWEVER, BY FRIDAY AND INTO THE WEEKEND, A SHORTWAVE WILL  
PUSH EAST ACROSS THE GREAT LAKES AND INTO NEW ENGLAND CAUSING HEIGHT  
FALLS LOCALLY. AT THE SAME TIME, A SURFACE COLD FRONT DRIVEN BENEATH  
THIS FEATURE WILL APPROACH SLOWLY FROM THE NW BEFORE STALLING AND  
DISSIPATING, LIKELY ON SUNDAY. THE COMBINATION OF CONTINUED WARM  
RETURN FLOW, LOWERED HEIGHTS ALOFT, AND THE FRONT ITSELF WILL ALL  
LEAD TO BETTER CONVECTIVE CHANCES LATE WEEK AND THROUGH THE WEEKEND.  
SETUP DOES NOT APPEAR TO SUPPORT WIDESPREAD OR ALL DAY RAIN CHANCES,  
BUT AFTN TSTM CHANCES WILL RAMP UP EACH DAY THROUGH SUNDAY BEFORE  
TAILING BACK TO CLIMO POP EARLY NEXT WEEK. THURSDAY/FRIDAY WILL  
FEATURE ABOVE NORMAL TEMPERATURES BEFORE INCREASED CLOUD COVER AND  
LOWER THICKNESSES CAUSE TEMPS TO DROP BACK TO NEAR NORMAL FOR THE  
WEEKEND AND INTO EARLY NEXT WEEK.  
 

 
   
AVIATION /15Z TUESDAY THROUGH SATURDAY/
 
 
AS OF 12Z...LOW STRATUS AND FOG PRODUCING LIFR CONDITIONS OVER  
THE ILM AIRPORT SHOULD BURN OFF AROUND 14Z. GROUND FOG PRESENT  
IN THE FLO AND LBT VICINITY WILL BURN OFF CONSIDERABLY QUICKER,  
PROBABLY BETWEEN 12-13Z. VFR CONDITIONS SHOULD DEVELOP ACROSS  
ALL OF THE AREA FOR THE BULK OF TODAY WITH LIGHT WINDS.  
SCATTERED THUNDERSTORMS DEVELOPING THIS AFTERNOON ACROSS CENTRAL  
NORTH CAROLINA MAY APPROACH THE LBT OR ILM AIRPORTS DURING THE  
LATE AFTERNOON OR EVENING HOURS, BUT THE POTENTIAL FOR A STRIKE  
ON EITHER AIRPORT IS TOO LOW FOR INCLUSION IN THE FORECAST AT  
THIS TIME.  
 
EXTENDED OUTLOOK...MAINLY VFR CONDITIONS EXPECTED TUESDAY-  
THURSDAY EXCEPT FOR PRE-DAWN GROUND FOG. THE POTENTIAL FOR  
THUNDERSTORMS WITH BRIEF IFR CONDITIONS BECOMES MORE LIKELY BY  
FRIDAY AND SATURDAY.  
 

 
   
MARINE
 
 
NEAR TERM /THROUGH TONIGHT/...  
AS OF 1045 AM TUESDAY...UPDATE HAS VERY LITTLE CHANGES. EXPECT  
SW WINDS TO BOUNCE BACK TO 10 TO 15 KT WITH OCCASIONAL GUSTS TO  
20 KT THIS AFTN AND EVENING. THIS AIDED BY A MID TO LATE AFTN  
SEABREEZE. BEST CHANCE FOR ANY CONVECTION THAT MOVES OFF THE  
MAINLAND WILL BE ACROSS THE ILM NC WATERS LATER THIS AFTN AND  
EVENING. COULD SEE A 30 KT WIND GUST FROM THE STRONGER  
CONVECTION. SIGNIFICANT SEAS WILL RANGE FROM 2 TO 4 FT AND  
PRIMARILY THE FUNCTION OF 4 TO 5 SECOND PERIOD WIND DRIVEN  
WAVES.  
 
PREVIOUS.................................................  
AS OF 300 AM TUESDAY...FRONTAL BOUNDARY WILL REMAIN ABOUT  
STALLED THROUGH THE PERIOD. THIS WILL KEEP WINDS OUT OF THE  
SOUTHWEST AS THEY HAVE BEEN FOR QUITE A WHILE NOW. THE PRESENCE  
OF THE FRONT WILL ALLOW FOR SOME LOW LEVEL JETTING AND THE WARM  
SSTS WILL ENCOURAGE VERTICAL MIXING OF SOME GUSTINESS...USUALLY  
TO THE TUNE OF 20KTS. THIS JETTING AND GUSTINESS SHOULD CONTINUE  
THROUGH THE PERIOD. SEAS WILL AVERAGE 2-4 FT, HIGHEST OFFSHORE.  
 
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...  
AS OF 300 AM TUESDAY...WE'RE EXPECTING A CLASSIC SUMMER WEATHER  
PATTERN WEDNESDAY AND THURSDAY WITH BERMUDA HIGH PRESSURE  
OFFSHORE AND A WEAK PIEDMONT TROUGH A COUPLE HUNDRED MILES  
INLAND. THESE TWO WEATHER FEATURES VIRTUALLY GUARANTEE A MODEST  
SOUTHWESTERLY WIND WILL PREVAIL ALONG WITH SEASONABLY WARM AND  
HUMID CONDITIONS. SEABREEZES SHOULD DEVELOP BOTH DAYS, WITH  
NEARSHORE WIND SPEEDS INCREASING TO 12-15 KNOTS DURING THE  
AFTERNOONS AND EVENINGS. SHOWERS AND THUNDERSTORMS SHOULD BE  
ISOLATED IN COVERAGE WITH DRY AIR ALOFT PREVENTING MORE ACTIVITY  
FROM DEVELOPING.  
 
LONG TERM /FRIDAY THROUGH SATURDAY...  
AS OF 300 PM MONDAY...HIGH PRESSURE OFFSHORE WILL REMAIN THE  
DOMINANT FEATURE, AND A COLD FRONT SLOWLY APPROACHING FROM THE  
NW WILL PINCH THE GRADIENT THROUGH THE PERIOD. SW WINDS WILL BE  
PERSISTENT ACROSS THE WATERS, BUT SPEEDS WILL INCREASE FROM 5-10  
KTS THURSDAY, TO 15-20 KTS BY SATURDAY. THESE INCREASING WINDS  
WILL HELP BUILD SEAS FROM 2-3 FT INITIALLY, TO 3-4 FT THE LATTER  
HALF OF THE PERIOD, WITH AN AMPLIFYING SW WIND WAVE MASKING THE  
2FT/8SEC SE SWELL.  
 

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

 
 

 
SYNOPSIS...TRA  
NEAR TERM...DCH/MBB  
SHORT TERM...TRA  
LONG TERM...JDW  
AVIATION...DCH/TRA  
MARINE...  
 
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