173  
FXUS62 KMHX 211349  
AFDMHX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC  
949 AM EDT TUE AUG 21 2018  
   
SYNOPSIS
 
 
A COLD FRONT WILL PASS THROUGH EASTERN NC WED NIGHT, BECOMING  
STATIONARY OVER THE OFFSHORE WATERS THIS WEEKEND, THEN  
DISSIPATING EARLY NEXT WEEK. HIGH PRESSURE WILL PASS TO THE  
NORTH THU AND FRI. THE BERMUDA HIGH WILL EXTEND INTO THE AREA  
BEGINNING EARLY NEXT WEEK.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 945 AM TUE...DEEP CYCLONIC FLOW WILL CONTINUE OVER MUCH  
OF THE EASTERN US TODAY COINCIDING WITH A PLUME OF TROPICAL  
MOISTURE CHARACTERIZED BY PW VALUES AOA 2" AND 850 MB DEWPOINTS  
AOA 14C. WHILE SHEAR CURRENTLY IS MARGINAL, IT SHOULD INCREASE  
LATER THIS AFTERNOON AS A SHORTWAVE ROTATES THROUGH THE MID  
LEVEL TROUGH. SINCE THIS IS FORECAST TO OCCUR DURING PEAK  
HEATING, BOTH COVERAGE AND INTENSITY OF CONVECTION IS EXPECTED  
TO INCREASE THIS AFTERNOON WITH FORECAST MUCAPES 2500-3000 J/KG  
EXPECTED. THIS SUPPORTS CURRENT SPC "MARGINAL" SEVERE OUTLOOK  
WITH DAMAGING WIND GUSTS THE MAIN THREAT, AND ALSO SUPPORTS THE  
WPC FORECAST OF A "MARGINAL" RISK FOR EXCESSIVE RAINS. THE 00Z  
NSSL-WRF INDICATES LOCAL RAINFALL AMOUNTS AROUND 3" POSSIBLE IN  
A SHORT PERIOD OF TIME WHICH COULD PRODUCE FLASH FLOODING. NO  
CHANGE TO FORECAST HIGHS OF 85 TO 90.  
 

 
   
SHORT TERM /WEDNESDAY/
 
 
AS OF 4 AM TUE...SIMILAR CONDITIONS CONTINUE INTO THE  
EVENING. UPPER TROF AXIS APPROACHES FROM THE WEST, DEEP MOISTURE  
IN PLACE AND VORT ENERGY PASSING THROUGH THE SOUTHWEST FLOW.  
WILL KEEP CHANCE POPS OVERNIGHT. LOWS WILL BE IN THE MID TO  
UPPER 70S THROUGHOUT.  
 

 
   
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
 
 
AS OF 4 AM TUE...UNSETTLE WEATHER WILL CONTINUE WEDNESDAY, THEN A  
COLD FRONT WILL PUSH THROUGH THE AREA WEDNESDAY NIGHT INTO THURSDAY.  
DRIER AIRMASS WILL MOVES INTO THE REGION THURSDAY AND FRIDAY  
REDUCING THE CHANCES OF PRECIP TO THE IMMEDIATE COASTLINE. DIURNALLY  
DRIVEN CONVECTION GRADUALLY INCREASE THIS WEEKEND AND EARLY NEXT  
WEEK.  
 
WEDNESDAY...SFC LOW CURRENTLY LOCATED OVER THE MIDWEST WILL CONTINUE  
TO STRENGTHEN AND MOVE INTO THE QUEBEC, CANADA BY WEDNESDAY WITH THE  
ATTENDANT COLD FRONT APPROACHING THE AREA FROM THE WEST. INSTABILITY  
INCREASES WITH CAPE VALUES REACHING NEAR 3500J/KG AND 0-6 KM SHEAR  
20-30 KT, MEANWHILE PRECIP WATER WILL BE APPROXLY AROUND 2 INCHES.  
THIS WILL LEAD TO ISOLATED STRONG TO SEVERE THUNDERSTORMS WITH  
POSSIBLE DAMAGING WIND GUSTS AND LOCALLY HEAVY RAINFALL WEDNESDAY.  
SPC HAS THE AREA IN MARGINAL RISK. HIGHS IN THE MID TO UPPER 80S,  
WITH LOWS IN THE 70S.  
 
WEDNESDAY NIGHT THROUGH FRIDAY...THE COLD FRONT WILL PUSH THROUGH  
THE AREA WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING, THEN STALL  
OFFSHORE THROUGH THE WEEKEND AS STRONG HIGH PRESSURE BUILDS IN FROM  
THE NORTHWEST/NORTH. A DRIER AND PLEASANT AIRMASS WILL BE PLACED  
OVER THE REGION, WHILE CHANCES OF PRECIP DIMINISHES THURSDAY AND  
FRIDAY, THOUGH WILL CONTINUE SC/LOW CHANCE POPS ALONG THE COAST NEAR  
AXIS OF BETTER MOISTURE. EXPECT TEMPS BELOW NORMAL, WITH HIGHS IN  
THE LOW TO MID 80S AND OVERNIGHT LOWS IN THE 60S TO LOW 70S.  
 
SATURDAY THROUGH MONDAY...POPS INCREASES AS THE SFC HIGH PRESSURE  
SLIDES OFFSHORE THIS WEEKEND AND MOISTURE INCREASES ACROSS THE AREA  
FOR THIS WEEKEND. MOSTLY EXPECT DIURNALLY DRIVEN SHOWERS AND  
THUNDERSTORMS EACH AFTERNOON. UPPER RIDGE WILL STRENGTHEN OVER THE  
AREA LATE WEEKEND INTO EARLY NEXT WEEK AS SURFACE HIGH REMAINS  
CENTERED JUST TO THE WEST. TEMPS WILL GRADUALLY WARM WITH PRECIP  
CHANCES RETURNING TO NEAR CLIMO.  
 

 
   
AVIATION /14Z TUESDAY THROUGH SATURDAY/
 
 
SHORT TERM /THROUGH 06Z WED/...  
AS OF 7 AM TUE...MAINLY VFR AGAIN DURING THE DAY TODAY WITH  
SUB-VFR IN SCATTERED TO NUMEROUS SHOWERS AND STORMS MAINLY THIS  
AFTERNOON. SUB-VFR CONDITIONS POSSIBLE CONTINUE TONIGHT WITH  
SCATTERED CONVECTION POSSIBLE. SURFACE WINDS SSW 10-15 KTS  
TODAY, LESS THAN 10 KTS TONIGHT.  
 
LONG TERM /WED THROUGH SAT/  
AS OF 4 AM TUE... SCATTERED SHOWERS AND THUNDERSTORMS WILL PRODUCE  
SUB-VFR CONDITIONS WITH THE HEAVIER SHOWERS. A COLD FRONT WILL PUSH  
THROUGH THE AREA WEDNESDAY NIGHT AND THURSDAY, WITH A DRIER AIRMASS  
MOVING INTO THE AREA...LEADING TO VFR CONDITIONS AFTERWARD.  
 

 
   
MARINE
 
 
SHORT TERM /THROUGH TONIGHT/  
AS OF 945 AM TUE...THE PRESSURE GRADIENT WILL TIGHTEN UP ACROSS  
THE AREA TODAY AND TONIGHT AS AN UPPER TROF/SURFACE COLD FRONT  
APPROACHES FROM THE WEST. WINDS WILL INCREASE TO 15-20 KNOTS ON  
THE COASTAL WATERS AND PAMLICO SOUND TODAY INTO TONIGHT, AND  
10-15 KNOTS ELSEWHERE. SEAS WILL BUILD TO 4-6 FEET LATE TONIGHT  
INTO EARLY WED FOR THE WATERS SOUTH OF OREGON INLET, SO HAVE  
POSTED A SMALL CRAFT ADVISORY FOR THOSE ZONES.  
 
LONG TERM /WED THROUGH SAT/  
AS OF 4 AM TUE...A COLD FRONT WILL APPROACH THE AREA  
WEDNESDAY AND PUSH THROUGH THE WATERS THURSDAY THEN STALL OFF  
THE COAST INTO THE WEEKEND. AHEAD OF THE COLD FRONT, SW WINDS  
15-20 KNOTS WITH HIGHER GUSTS AND SEAS BUILDING 4-6 FT SOUTH OF  
OREGON INLET; SCA WILL BE IN EFFECT DURING THIS TIME PERIOD.  
WINDS WILL THEN SHIFT NE/E 5-15 KT THURSDAY AND FRIDAY, AND BY  
SATURDAY EASTERLY 5-10 KT. SEAS WILL SUBSIDE 2-4 FT THURSDAY AND  
FRIDAY, THEN BECOMING 2-3 FT SATURDAY.  
 

 
   
MHX WATCHES/WARNINGS/ADVISORIES
 
 
NC...NONE.  
MARINE...SMALL CRAFT ADVISORY FROM 5 AM WEDNESDAY TO 1 AM EDT THURSDAY  
FOR AMZ152-154.  
SMALL CRAFT ADVISORY FROM 5 AM TO 10 PM EDT WEDNESDAY FOR  
AMZ156.  
SMALL CRAFT ADVISORY FROM 10 AM TO 10 PM EDT WEDNESDAY FOR  
AMZ158.  
 

 
 

 
SYNOPSIS...JME/HSA  
NEAR TERM...JME/HSA  
SHORT TERM...HSA  
LONG TERM...BM  
AVIATION...HSA/BM  
MARINE...JME/HSA/BM  
 
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