083  
FXUS62 KILM 220717  
AFDILM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON NC  
317 AM EDT MON OCT 22 2018  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL MOVE OFF THE NORTH CAROLINA COAST TODAY. A  
SECOND CANADIAN HIGH WILL BUILD INTO THE GREAT LAKES LATE  
TUESDAY, PUSHING ANOTHER COLD FRONT THROUGH THE AREA. LOW  
PRESSURE WILL DEVELOP ALONG THE GULF COAST THURSDAY, BRINGING  
GOOD RAIN CHANCES TO THE CAROLINAS FRIDAY INTO EARLY SATURDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 300 AM MONDAY...COLD ADVECTION SHUTTING OFF AND ACTUALLY SLATED  
TO REVERSE SHORTLY. WITH HIGH PRESSURE STILL NEARBY AND BRINGING A  
LIGHT NE TO VARIABLE WIND HOWEVER MIXING WILL REMAIN QUITE SHALLOW  
AND HEATING UP ALL THE WAY TO CLIMATOLOGY (SOME 30 DEGREES ABOVE  
PREDAWN LOWS) WILL BE TOO TALL AN ORDER. MOST PLACES WILL GET CLOSE  
HOWEVER; HIGHS IN THE UPPER 60S WILL BE GENERALLY 5 DEGREES BELOW  
SEASONABLE NORMS. THE WARM ADVECTION WILL ON THE OTHER HAND PREVENT  
A REPEAT OF THIS MORNING'S CHILL; WITH AREAS GENERALLY REMAINING IN  
THE MID 40S TO LOW 50S ALONG THE COAST.  
 

 
   
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
 
 
AS OF 300 AM MONDAY...AN UPPER LEVEL TROUGH ACROSS SE CANADA AND  
A RIDGE BUILDING ACROSS THE PLAINS STATES WILL MAINTAIN A  
NORTHWESTERLY 500 MB FLOW OVER THE CAROLINAS. AT THE SURFACE,  
HIGH PRESSURE SUPPORTED BY THE UPPER RIDGE WILL BUILD ACROSS THE  
WESTERN GREAT LAKES, PUSHING A COLD FRONT SOUTHWARD THROUGH THE  
CAROLINAS TUESDAY EVENING. MOISTURE RETURN AHEAD OF THIS FRONT  
SHOULD BE MEAGER AND QUITE SHALLOW. IT IS REMINISCENT TO THE  
SYSTEM THAT PASSED THROUGH HERE LAST SATURDAY WHERE SCATTERED  
LIGHT SHOWERS REMAINED OFFSHORE. I'LL MAINTAIN A FORECAST OF  
CONSIDERABLE CLOUDS TUESDAY BUT WITH DRY CONDITIONS CONTINUING  
INLAND FROM THE BEACHES.  
 
GFS/ECMWF WERE FOLLOWED CLOSELY FOR TEMPERATURES THROUGH THE  
PERIOD. HIGHS LOWER TO MID 70S TUESDAY WILL COOL INTO THE UPPER  
60S WEDNESDAY. LOWS AROUND 50 TUESDAY NIGHT SHOULD FALL INTO THE  
MID 40S WEDNESDAY NIGHT. THOSE WEDNESDAY NIGHT LOWS ARE A LITTLE  
UNCERTAIN AS MOST MODELS SHOW DENSE CIRRUS STREAMING THROUGH THE  
UPPER RIDGE FROM THE REMNANTS OF PACIFIC HURRICANE WILLA AS IT  
STREAKS EASTWARD ALONG THE GULF COAST. HOW MUCH IMPACT THIS WILL  
HAVE ON RADIATIONAL COOLING IS UNCERTAIN.  
 

 
   
LONG TERM /THURSDAY THROUGH SUNDAY/
 
 
AS OF 300 PM FRIDAY...CANADIAN HIGH PRESSURE WILL BUILD DOWN  
INTO THE CAROLINAS THROUGH MID WEEK. THIS WILL PRODUCE BELOW  
NORMAL TEMPS WITH ANOTHER SURGE OF COLD AIR AND DRY AIR. TEMPS  
BOTH WED NIGHT AND THURS NIGHT WILL BE DOWN NEAR 40, EXCEPT  
WARMER RIGHT ALONG THE COAST. TEMPS WILL REMAIN IN THE 60S FOR  
MAX TEMPS THROUGH MUCH OF THE LONG TERM PERIOD.  
 
BY FRIDAY, LOW PRESSURE MOVING UP FROM THE GULF COAST WILL BEGIN  
TO SPREAD CLOUDS AND RAIN NORTHWARD. IF CLOUDS MOVE IN EARLIER  
ON FRI, COULD END UP BEING COOLER WITH TEMPS POSSIBLY NOT EVEN  
MAKING IT TO 60 DEGREES IN PLACES, BUT OVERALL EXPECT A CLOUDY,  
COOL AND RAINY WEATHER TO DEVELOP FRI AND SAT AS LOW PRESSURE  
DEEPENS AS IT MOVES UP THE SOUTHEAST COAST. THE SHALLOW COOL  
DENSE AIR WILL BE OVERRUN WITH THE WARMER MOISTER AIR TO  
PRODUCE LOW CLOUDS AND RAIN ACROSS MUCH OF THE FORECAST AREA.  
SOME WARMER AIR MAY REACH COASTAL AREAS IN A MORE EASTERLY FETCH  
ON THE TOP SIDE OF THE LOW IF IT MOVES CLOSE ENOUGH. BUT MOST  
PLACES SHOULD REMAIN IN THE COOLER NORTHERLY FLOW ON BACK END,  
LEAVING ANY CONVECTION CONFINED TO MAINLY OFF THE COAST. MAY SEE  
SOME DRYING ON THE BACK END BY THE END OF THE WEEKEND, BUT ITS  
TOO FAR OUT TO SAY WITH ANY CERTAINTY. IT WILL DEPEND ON HOW THE  
MID TO UPPER LOW DIVING DOWN FROM THE UPPER MIDWEST EVOLVES  
OVER TIME. LOOKS LIKE A FAIRLY SATURATED COLUMN LATE FRI THROUGH  
SATURDAY WITH CLOUDS AND RAIN A LIKELY SCENARIO.  
 

 
   
AVIATION /06Z MONDAY THROUGH FRIDAY/
 
 
AS OF 06Z...VFR WITH CLEAR SKIES. LIGHT N TO NE WINDS WILL BECOME  
LIGHT AND VARIABLE AS HIGH PRESSURE JUST NORTH OF THE REGION EXTENDS  
A RIDGE AXIS OVERHEAD.  
 
EXTENDED OUTLOOK...VFR MON/WED/THU. CHANCE OF MVFR CIGS/ISOLATED  
SHOWERS TUE AT THE COASTAL TERMINALS, MOST LIKELY KMYR, AS A WEAK  
COLD FRONT MOVES THROUGH. MVFR/IFR/RA/WINDY FRI AS LOW PRESSURE  
MOVES UP THE COAST.  
 

 
   
MARINE
 
 
NEAR TERM /THROUGH TONIGHT/...  
AS OF 300 AM MONDAY...WINDS HAVE DROPPED OFF AND WILL REMAIN  
LIGHT AS HIGH PRESSURE BOTH PASSES BY TO THE NORTH AND EXTENDS A  
RIDGE AXIS OVERHEAD. SEAS AS ALWAYS WILL BE SLOWER TO ABATE;  
THOUGH THE RELAXATION HAS ALREADY DROPPED SIG WAVE HEIGHT TO  
3.5FT ALL THE WAY OUT TO 41013. BY LATER TODAY BOTH WIND AND  
SEAS WILL DROP TO ALMOST MINIMAL VALUES; 10KT OR LESS AND  
GENERALLY 2 FT OR LESS.  
 
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...  
AS OF 300 AM MONDAY...A COLD FRONT WILL MOVE ACROSS THE COASTAL  
WATERS TUESDAY EVENING AS HIGH PRESSURE BUILDS INTO THE WESTERN  
GREAT LAKES. NORTHEASTERLY WINDS WILL INCREASE TO 15-20 KT  
WEDNESDAY BEHIND THE FRONT, WITH SEAS BUILDING TO A SOLID 4 FEET  
WITH A CHANCE OF 5-FOOTERS 15-20 MILES FROM SHORE.  
 
LONG TERM /THURSDAY THROUGH FRIDAY/...  
AS OF 300 PM SUNDAY...COOL CANADIAN HIGH PRESSURE WILL BUILD  
DOWN OVER THE WATERS THROUGH MID WEEK. THIS NORTHERLY SURGE WILL  
WILL PRODUCE AN INCREASE IN WINDS AND SEAS WED INTO THURS. THE  
COLD AIR RUSHING OVER THE WARMER WATERS WILL KEEP THE MARINE  
LAYER WELL MIXED WITH GUSTY NORTHERLY WINDS WED NIGHT THROUGH  
THURS NIGHT. WINDS AND SEAS MAY REACH INTO SCA THRESHOLDS WED  
NIGHT INTO EARLY THURS, AS NE WINDS MAY INCREASE UP TO 15 TO 25  
KTS AND SEAS REACH ABOVE 6FT.  
 
BY FRIDAY, LOW PRESSURE WILL BEGIN TO MOVE UP FROM THE GULF  
COAST. MODELS SHOW THIS LOW DEEPENING AS IT TRACKS UP ALONG OR  
JUST OFF THE COAST. THE DEEPENING LOW SHOULD PRODUCE A  
TIGHTENED GRADIENT FLOW ACROSS THE SOUTHEAST COASTAL WATERS.  
EXPECT STRONG NE WINDS, BUT NEED TO SEE EXACTLY HOW THE LOW  
EVOLVES BEFORE WE SAY WITH ANY CERTAINTY.  
 

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

 
 

 
 
SYNOPSIS...TRA  
NEAR TERM...MBB  
SHORT TERM...TRA  
LONG TERM...RGZ  
AVIATION...MBB  
 
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