420  
FXUS62 KILM 180153  
AFDILM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON NC  
953 PM EDT SAT APR 17 2021  
   
SYNOPSIS
 
 
WEAK HIGH PRESSURE WILL KEEP THE AREA DRY THROUGH THE REMAINDER  
OF THE WEEKEND. WEAK LOW PRESSURE MOVING SOUTH OF CAPE FEAR WILL  
BRING SMALL RAIN CHANCES EARLY MONDAY. A DRY COLD FRONT WILL  
CROSS THE COAST LATE WEDNESDAY, WITH COOLER HIGH PRESSURE MOVING  
IN THURSDAY AND FRIDAY. A STORM SYSTEM WILL APPROACH FROM THE  
GULF COAST STATES ON SATURDAY, AND RAIN CHANCES WILL INCREASE.  
 

 
   
UPDATE
 
 
NO CHANGES THIS UPDATE.  
 

 
   
NEAR TERM /THROUGH SUNDAY NIGHT/
 
 
A WEAK POCKET OF SHORTWAVE ENERGY ALONG THE FLORIDA PANHANDLE WILL  
CONTINUE TO PROGRESS ENE OVERNIGHT. THIS ENERGY HAS SPAWNED THE  
DEVELOPMENT OF A SERIES OF WEAK LOW PRESSURE SYSTEMS (PROBABLY  
BETTER DESCRIBED AS WEAK WAVES OF LOW PRESSURE), MOVING OF THE GA  
COAST AND PROGRESSING OFFSHORE OVERNIGHT. THE FINALE OF THESE  
SYSTEMS MAY BRING ISOLATED SHOWERS ALONG THE SC OR EXTREME SOUTHERN  
NC COASTLINE TONIGHT. SOUNDINGS AND ASSOCIATED SATELLITE IMAGERY  
SHOW DRY AIR IN THE LOW-LEVELS WHICH WILL INHIBIT SHOWER DEVELOPMENT  
ON A SCATTERED OR WIDESPREAD SCALE. IF ANY SHOWERS DEVELOP, EXPECT  
ONLY A SMALL AMOUNT OF QPF IF ANY AT ALL (LESS THAN A TENTH OF AN  
INCH). CLOUDS OVERNIGHT WILL IMPACT TEMPERATURES WITH LOWS SCHEDULED  
IN THE MID 50S INLAND TO UPPER 50S ALONG THE COAST.  
 
ON SUNDAY, WEAK SURFACE LOW PRESSURE AND ANY UPPER-LEVEL ENERGY WILL  
CONTINUE TO PUSH OFFSHORE AS SHOWER CHANCES COME TO AN END. MOST OF  
THE DAY WILL REMAIN DRY WITH A GOOD AMOUNT OF CLOUD COVERAGE.  
SOUNDINGS CONTINUE TO SHOW DRY AIR THROUGHOUT THE LOW-LEVELS, BUT  
LINGERING MOISTURE IN THE MID-LEVELS NEAR A SUBSIDENCE INVERSION IS  
LIKELY TO HANG AROUND THROUGH MUCH OF THE DAY. COULD SEE A FEW PEEKS  
OF SUNSHINE DURING THE AFTERNOON AS DRY AIR STARTS TO DESCEND AND  
ERODES SOME OF THE THINNING CLOUD COVER. HIGHS SHOULD REMAIN RIGHT  
AROUND NORMAL: IN THE MID-70S. STRONGER SHORTWAVE WILL APPROACH THE  
AREA FROM THE WEST SUNDAY NIGHT INTO EARLY MONDAY. THE BEST FORCING  
AND ASSOCIATED RAIN CHANCES WILL STAY TO OUR NORTH NEAR THE  
VORTICITY MAXIMUM OVER NORTHERN NC AND SOUTHERN VA. MOISTURE AGAIN  
APPEARS TO BE LIMITED WITH THIS SYSTEM, BUT THE BETTER FORCING MAY  
REQUIRE SLIGHTLY HIGHER POPS THROUGH MONDAY MORNING. OVERNIGHT LOWS  
IN THE LOW 50S WITH MID 50S ALONG THE COAST.  
 

 
   
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
 
 
PROGRESSIVE MID-LEVEL FLOW OVER THE AREA WILL PUSH A WEAK SURFACE  
TROUGH/LOW OFF THE COAST EARLY MONDAY, FOLLOWED BY A LIGHT NORTHERLY  
BREEZE. MAY SEE A FEW LIGHT SHOWERS MONDAY MORNING, HOWEVER MOISTURE  
IS A LIMITING FACTOR, AND IT'S CONFINED BELOW ABOUT 800 MB. A LOW-  
AMPLITUDE 500 MB RIDGE WILL TRAVERSE THE AREA MONDAY NIGHT, AND  
SURFACE WINDS WILL VEER TO THE EAST AS SURFACE HIGH PUSHES OFF  
THE NC/VA COAST. MID-LEVEL MOISTURE WILL INCREASE TUESDAY AS  
SYNOPTIC FLOW TURNS SW AHEAD OF A BROAD TROUGH SWINGING ACROSS  
THE CENTRAL PLAINS. DEEPENING SURFACE LOW WILL LIFT ACROSS THE  
OHIO RIVER VALLEY TUESDAY NIGHT, AND ASSOCIATED SURFACE COLD  
FRONT WILL CROSS THE APPALACHIANS INTO THE WESTERN CAROLINAS  
LATE TUESDAY NIGHT. FORCING WILL BE WEAK BUT COULD SEE A FEW  
SHOWERS POP UP TUESDAY AFTERNOON INTO THE EVENING. MAX TEMPS  
THIS PERIOD SHOULD BE WITHIN A COUPLE OF DEGREES OF NORMAL FOR  
MID APRIL (MID 70S). LOW TEMPS MONDAY NIGHT WILL ALSO BE CLOSE  
TO NORMAL (LOW-MID 50S), THEN A COUPLE OF DEGREES WARMER TUESDAY  
NIGHT WITH ONSHORE FLOW.  
 

 
   
LONG TERM /WEDNESDAY THROUGH SATURDAY/
 
 
A BROAD MID/UPPER TROUGH WILL SHIFT EAST OF THE MISSISSIPPI RIVER  
VALLEY WEDNESDAY, WITH A WEAK EMBEDDED 500 MB SHORTWAVE MAKING ITS  
WAY OFF THE COAST LATE THURSDAY AFTERNOON OR EARLY THURSDAY EVENING.  
THE ASSOCIATED SURFACE LOW WILL LIFT ACROSS THE NORTHEAST CONUS  
WEDNESDAY NIGHT, AND A RESPECTABLE COLD FRONT WILL PUSH ACROSS THE  
AREA EASTERN CAROLINAS WEDNESDAY AFTERNOON. MOISTURE WILL BE  
LACKING, SO POPS, IF ANY, ON WEDNESDAY WILL BE MINIMAL. COOL HIGH  
PRESSURE WILL BUILD IN WEDNESDAY NIGHT AND THURSDAY, WITH A  
SECONDARY DRY COLD FRONT EXPECTED TO PUSH ACROSS THE AREA THURSDAY  
EVENING. THE NEXT SYSTEM WILL BE PUSHING ACROSS THE GULF COAST  
STATES FRIDAY NIGHT INTO SATURDAY, RESULTING IN INCREASING POPS FROM  
SW TO NE DURING THE DAY.  
 

 
   
AVIATION /02Z SUNDAY THROUGH THURSDAY/
 
 
VFR, BUT WITH CLOUDS ABUNDANT TONIGHT AND EARLY SUNDAY ABOVE  
8000 FEET, AS A STREAM OF RAIN PASSES OFFSHORE OF GEORGIA AND  
SOUTHERN SOUTH CAROLINA. CLOUDS TO DECREASE FOR THE LAST 12  
HOURS OF TAF CYCLE DURING SUNDAY, WITH FEW/SCT150 BY MID-  
AFTERNOON. A WEAK SHIFT IS EXPECTED TONIGHT BETWEEN 6-9Z, BUT  
WINDS ARE SO LIGHT THAT THE CHANGE IN WIND DIRECTION WILL HAVE  
LITTLE IMPACT ON AVIATION.  
 
EXTENDED OUTLOOK...VFR, WITH OCCASIONAL MIDDLE AND HIGH CLOUDS  
AS SEVERAL WEAK WAVES TRAVERSE THE REGION. A MODERATELY STRONG  
COLD FRONT WEDNESDAY NIGHT MAY BRING RESTRICTIONS.  
 

 
   
MARINE
 
 
THROUGH SUNDAY NIGHT: WINDS REMAIN LIGHT AND VARIABLE  
THROUGHOUT THE NEAR-TERM PERIOD. SOUTHERLY WINDS THIS EVENING  
AROUND 10 KNOTS WILL BECOME NW BEHIND AN EXITING SURFACE LOW BY  
SUNDAY MORNING. AFTER A BRIEF PERIOD OF OFFSHORE WINDS ON  
SUNDAY, WINDS BECOME SW AHEAD OF THE NEXT WEAK WAVE OF LOW  
PRESSURE TRAVERSING THE APPALACHIANS ON SUNDAY NIGHT. WAVES  
THROUGHOUT THE PERIOD MAINTAIN AROUND 2 FEET DUE TO THE VARIABLE  
WINDS WITH NO SIGNIFICANTLY BUILDING WAVE ENERGY.  
 
MONDAY THROUGH THURSDAY: A WEAK SURFACE TROUGH OVER THE AREA WATERS  
MONDAY WILL LEAD TO VARIABLE WINDS GENERALLY 10 KTS OR LESS. ENE  
WINDS WILL DEVELOP LATE MONDAY AFTERNOON INTO THE EVENING AS THE LOW  
SLIDES EAST AND WEAK HIGH PRESSURE MOVES OFF THE NC/VA COAST. WIND  
SPEEDS WILL REMAIN RELATIVELY LIGHT, WITH AN ONSHORE COMPONENT,  
THROUGH TUESDAY, BECOMING S-SW TUESDAY NIGHT AHEAD OF A COLD FRONT.  
SPEEDS WILL INCREASE TUESDAY NIGHT AND WEDNESDAY AS THE FRONT  
CROSSES THE CAROLINAS, AND IT WILL MOVE ACROSS THE WATERS IN THE  
WEDNESDAY EVENING TIME FRAME. A STRONG POST-FRONTAL GRADIENT LOOKS  
TO PUSH NW WINDS TO 20-25 KTS WEDNESDAY NIGHT. THE GRADIENT WILL  
RELAX BY THURSDAY MORNING, AND ALTHOUGH WINDS WILL REMAIN WNW,  
SPEEDS SHOULD FALL TO 10-15 KTS.  
 

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

 
 

 
 
UPDATE...8  
NEAR TERM...21  
SHORT TERM...CRM  
LONG TERM...CRM  
AVIATION...MJC  
MARINE...21/CRM  
 
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