025  
FXUS62 KILM 222004  
AFDILM  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE WILMINGTON NC  
404 PM EDT SUN APR 22 2018  
   
SYNOPSIS
 
 
A SLOW MOVING LOW PRESSURE SYSTEM WILL CROSS THE SOUTHEASTERN  
U.S. AND PRODUCE BENEFICIAL RAINS OF 2 TO 4 INCHES MONDAY  
THROUGH TUESDAY. TEMPERATURES BELOW NORMAL THROUGH TUESDAY WILL  
BOUNCE BACK TO NEAR NORMAL FOR THE REST OF THE WEEK. A COLD  
FRONT MAY DROP DOWN INTO THE CAROLINAS WEDNESDAY NIGHT. ANOTHER  
AREA OF LOW PRESSURE MAY AFFECT THE AREA ON THURSDAY FOLLOWED  
BY HIGH PRESSURE ON FRIDAY WITH BELOW NORMAL TEMPERATURES  
HEADING INTO THE WEEKEND.  
 

 
   
NEAR TERM /THROUGH MONDAY/
 
 
AS OF 330 PM SUNDAY...SURFACE RIDGE IS MAINTAINING INFLUENCE ACROSS  
THE CAROLINAS AT THE MOMENT. MEANWHILE AREAS OF LOW PRESSURE ARE  
ESTABLISHED ACROSS THE MS VALLEY SUPPORTED BY THE OLD UPPER LOW  
ACROSS NORTHERN ARKANSAS. AS LOW PRESSURE DRIFTS EAST THE WEATHER  
WILL CHANGE DRASTICALLY ACROSS THE CAROLINAS DURING MONDAY. A  
STRENGTHENING ONSHORE WIND WILL SUPPORT MARGINAL WIND ADVISORY  
CRITERIA ALONG THE COASTAL ZONES WHILE ADVECTING A LOT OF MOISTURE  
INTO THE REGION. IN FACT, THE PRECIPITABLE WATER SHOULD APPROACH 1.7  
INCHES DURING MONDAY AS CONDITIONS COME TOGETHER FOR A WIDESPREAD  
HEAVY RAIN EVENT. INCREASING LOW-LEVEL CONVERGENCE ALONG WITH AND  
EXCELLENT DIVERGENCE ALOFT WILL CREATE STRONG UPWARD VERTICAL  
VELOCITY. AS A RESULT OF THE COLUMN SATURATION AND STRONG LIFT WE  
ANTICIPATE 2-4 INCHES ACROSS THE FORECAST AREA. WHILE SURFACE BASED  
INSTABILITY IS LACKING THE STRONG DYNAMICS WARRANTS MENTIONING  
ISOLATED EMBEDDED THUNDERSTORMS AS WELL. WHILE SOME FLOOD PRONE/POOR  
DRAINAGE AREAS MAY RECEIVE FLOODING DO NOT THINK FLOOD IMPACTS WILL  
BE WIDESPREAD ENOUGH FOR A FLOOD WATCH AT THIS TIME.  
 

 
   
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/
 
 
AS OF 330 PM SUNDAY...AS THE AREA OF LOW PRESSURE ACROSS TN/KY FILLS  
THE LOW PROGGED TO BE ACROSS GA/SC WILL BECOME DOMINANT AND LIFT  
NORTHEAST ACROSS THE CAROLINAS DURING TUESDAY. AS THE LOW MOVES  
NORTHEAST THE STRONG AXIS OF ONSHORE WINDS WILL SHIFT INTO EASTERN  
NC BY TUESDAY MORNING. THE AXIS OF HEAVIEST RAINFALL WILL ALSO SHIFT  
NORTHWARD AS WELL DURING TUESDAY WITH DRIER MID-LEVEL AIR PUSHING IN  
FROM THE SOUTH AND SOUTHWEST. POPS WILL TREND LOWER BY LATER IN THE  
DAY WITH 20-30 POPS LINGERING FOR TUESDAY NIGHT. FOLLOWED A BLEND OF  
MAV/MET NUMBER FOR TEMPERATURES. WILL NEED TO KEEP AN EYE ON THE  
HIGH TIDE MONDAY NIGHT INTO EARLY TUESDAY MORNING AS WELL - MORE ON  
THE POTENTIAL FOR COASTAL FLOODING BELOW  
 

 
   
LONG TERM /WEDNESDAY THROUGH SATURDAY/
 
 
AS OF 300 PM SUNDAY...AS ONE AREA OF LOW PRESSURE LIFTS OFF TO  
THE NORTHEAST AWAY FROM THE CAROLINAS ON WED, ANOTHER ONE WILL  
FOLLOW BEHIND IT ROTATING AROUND THE MAIN UPPER TROUGH IN A  
FAIRLY PROGRESSIVE PATTERN. THE WINDS WILL VEER AROUND ON WED  
ON THE BACK END OF THE INITIAL LOW AS IT PULLS AWAY AND MAY SEE  
A WEAK BOUNDARY OR FRONT DROP DOWN INTO THE CAROLINAS WED NIGHT  
INTO EARLY THURS. THE WESTERLY DOWNSLOPE FLOW ON WED SHOULD  
COMBINE WITH MIXED SUN AND CLOUDS TO PRODUCE TEMPS CLOSE TO 80  
ON WED.  
 
THE SECOND LOW WILL TRACK DOWN FROM THE UPPER MIDWEST, BECOMING  
AN OPEN WAVE AS IT DIGS DOWN INTO THE LOWER MISSISSIPPI VALLEY  
BY THURS. THE GFS AND ECMWF BOTH SHOW THIS LOW MOVING NORTHEAST  
THROUGH THE COASTAL CAROLINAS THURS NIGHT INTO FRI, BUT THE GFS  
IS DEEPER AND SHOWING GREATER QPF AND WINDS OVERNIGHT THURS. BY  
FRIDAY, THIS SYSTEM WILL LIFT OFF TO THE NORTHEAST WITH A DECENT  
DAY IN STORE. THE GFS AND ECMWF DIFFER QUITE A BIT HEADING INTO  
THE WEEKEND WITH THE GFS SHOWING A MUCH DRIER FORECAST. EITHER  
WAY, A TROUGH WILL MOVE ACROSS THE EAST COAST PRODUCING BELOW  
NORMAL TEMPS THROUGH MUCH OF THE LATE WEEK PERIOD.  
 

 
   
AVIATION /18Z SUNDAY THROUGH FRIDAY/
 
 
AS OF 18Z...GENERAL ONSHORE FLOW WILL PERSIST THROUGH MONDAY AS LOW  
PRESSURE SLOWLY DRIFTS ACROSS THE MID-MISSISSIPPI VALLEY. EXPECT VFR  
CONDITIONS THROUGH THE REMAINDER OF THE AFTERNOON AND INTO THE  
EVENING, THEN CEILINGS LOWERING TO MVFR LATE TONIGHT AS RAINFALL  
OVERSPREADS THE TERMINALS FROM SW TO NE. PRECIP SHOULD BE ON THE  
DOORSTEP OF KILM BY 18Z MON.  
 
EXTENDED OUTLOOK...MVFR AND POSSIBLE IFR WILL PERSIST MONDAY NIGHT  
INTO EARLY TUESDAY ASSOCIATED WITH WIDESPREAD RAINFALL. WED THROUGH  
THURSDAY EXPECT VFR. MVFR POSSIBLE THURSDAY NIGHT WITH A COLD FRONT,  
THEN CLEARING FRIDAY.  
 

 
   
MARINE
 
 
NEAR TERM /THROUGH MONDAY/...  
AS OF 330 PM SUNDAY...HIGH PRESSURE CENTERED JUST EAST OF DELMARVA  
WILL MAINTAIN AN ONSHORE FLOW ACROSS THE ADJACENT COASTAL WATERS  
THROUGH TONIGHT. AS LOW PRESSURE MEANDERS ALONG THE MS VALLEY  
THROUGH MONDAY THE PRESSURE GRADIENT BETWEEN THE HIGH AND LOW WILL  
ALLOW THE ONSHORE FETCH TO INCREASE WITH MARGINAL SUSTAINED GALES  
BECOMING LIKELY. IN REGARDS TO THE SMALL CRAFT ADVISORY WE HAVE MOVED  
THE START TIME EARLIER, AND UPGRADED THE GALE WATCH TO A GALE WARNING.  
SEAS SHOULD HAVE NO PROBLEM EXCEEDING 10 FEET GIVEN THE SIZE,  
ORIENTATION, AND STRENGTH OF THE FETCH. NUMEROUS SHOWERS EXPECTED TO  
DEVELOP BY MONDAY, ESPECIALLY ACROSS THE SOUTHERN WATERS INITIALLY.  
EMBEDDED ISOLATED THUNDERSTORMS ARE ALSO POSSIBLE.  
 
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...  
AS OF 330 PM SUNDAY...GALES WILL CONTINUE AT THE ONSET OF THE SHORT  
TERM PERIOD WITH COMPLEX AREAS OF LOW PRESSURE FROM TN/KY TO SC/GA.  
THE AXIS OF STRONG WINDS WILL GRADUALLY SHIFT ACROSS THE WATERS OFF  
EASTERN NC DURING TUESDAY WHILE THE RESIDUAL SEAS WILL REMAIN HIGH  
THROUGH THE DAY. AT SOME POINT DURING TUESDAY THE GALE WARNING WILL  
NEED TO BE LOWERED IN FAVOR OF ANOTHER SMALL CRAFT ADVISORY UNTIL  
SEAS SUBSIDE LATER IN THE DAY. BY TUESDAY NIGHT, THE SC/GA LOW WILL  
HAVE TRANSLATED TO NORTHEAST NC/SOUTHEAST VA WITH A MUCH WEAKENED  
PRESSURE GRADIENT IN PLACE OVERNIGHT. SEAS WILL BE HIGHEST TUESDAY  
MORNING, THEN GRADUALLY SUBSIDE DURING THE AFTERNOON. SEAS WILL  
CONTINUE TO SUBSIDE TUESDAY NIGHT.  
 
LONG TERM /WEDNESDAY THROUGH FRIDAY/...  
AS OF 300 PM SUNDAY...WINDS WILL DIMINISH AS THEY SHIFT AROUND  
FROM ON SHORE TO OFF SHORE WED ON THE BACK END OF LOW PRESSURE  
SYSTEM, AS IT LIFTS OFF TO THE NORTHEAST. A DRY COLD FRONT MAY  
DROP INTO THE WATERS WED NIGHT INTO THURS WITH WINDS SHIFTING  
AROUND TO A MORE N-NE DIRECTION ON THURS. FAIRLY LOW CONFIDENCE  
FORECAST THURS INTO FRI AS ANOTHER AREA OF LOW PRESSURE MAY  
AFFECT THE WATERS.  
 
AS THE WINDS SHIFT AROUND TO OFF SHORE AND LIGHTEN ON WED, SEAS  
WILL SUBSIDE. SEAS SHOULD BE 3 TO 5 FT WED MORNING DROPPING DOWN  
TO 2 TO 4 FT BY THURS MORNING. WINDS AND SEAS WILL BE DEPENDENT  
ON STRENGTH AND TRACK OF LOW PRESSURE LATE THURS INTO FRI, BUT  
FOR NOW HAVE LEFT THEM IN THE 3 TO 5 FT RANGE, ALTHOUGH THE WNA  
SHOWS POTENTIAL FOR SCA CONDITIONS EARLY FRI.  
 

 
   
CLIMATE
 
 
AS OF 300 PM SUNDAY...  
METEOROLOGICAL SPRING BEGAN ON MARCH 1ST, AND TEMPERATURES SINCE  
THEN HAVE AVERAGED SIGNIFICANTLY BELOW NORMAL. THIS HAS BEEN  
ESPECIALLY TRUE FOR LOW TEMPERATURES WHICH ARE RUNNING AMONG THE  
COOLEST VALUES OBSERVED UP THROUGH THIS POINT IN THE YEAR.  
 
HERE ARE SOME STATISTICS ON LOW TEMPERATURES SINCE MARCH 1ST.  
 
WILMINGTON, NC  
COLDEST AVERAGE DAILY LOW TEMPS MARCH 1 THROUGH APRIL 21  
RANK AVG TEMP YEAR  
1 41.01915  
2 41.61960  
3 42.21971  
4 42.81962  
4 42.82018 <--  
6 43.1 1926  
6 43.11981  
 
WILMINGTON, NC  
MOST NUMBER OF MARCH + APRIL NIGHTS WITH LOWS <=40  
RANK # OF NIGHTS YEAR  
1 34 1915  
2 26 1960  
3 25 1962  
4 24 1971  
5 23 2018 <--  
5 23 1996  
5 23 1983  
5 23 1981  
5 23 1969  
 
FLORENCE, SC  
COLDEST AVERAGE DAILY LOW TEMPS MARCH 1 THROUGH APRIL 21  
RANK AVG TEMP YEAR  
1 38.81966  
2 40.01960  
3 41.81950  
4 42.11971  
5 42.41962  
6 42.61996  
7 43.02014  
8 43.32013  
9 43.52018 <--  
10 43.81984  
10 43.81956  
12 43.92005  
 
FLORENCE, SC  
MOST NUMBER OF MARCH + APRIL NIGHTS WITH LOWS <=40  
RANK # OF NIGHTS YEAR  
1 30 1966  
2 28 1950  
3 27 1960  
4 25 1971  
5 24 2013  
5 24 1962  
7 22 2014  
7 22 1996  
9 21 2005  
9 21 1992  
9 21 1983  
9 21 1956  
13 20 2018 <--  
13 20 1987  
 

 
   
TIDES/COASTAL FLOODING
 
 
AS OF 330 PM SUNDAY...THE STRENGTHENING ONSHORE FETCH MAY LEAD TO  
SOME MINOR OCEAN OVERWASH, ESPECIALLY WITH HIGH TIDE LATE MONDAY  
NIGHT INTO TUESDAY MORNING. CONFIDENCE IS HIGHER WITH MINOR COASTAL  
FLOODING FOR THE NC COASTAL WATERS WHEN THE AXIS OF STRONGEST WINDS  
ARE COINCIDENT WITH THAT PARTICULAR HIGH TIDE. IF CURRENT TRENDS  
CONTINUE THEN A COASTAL FLOOD ADVISORY MAY BE NEEDED LATE MONDAY  
NIGHT. MINOR FLOODING MAY ALSO EXTEND INTO THE DOWNTOWN  
WILMINGTON/BATTLESHIP AREA WITH THE SAME TIDE. FORTUNATELY,  
REGARDING ASTRONOMICAL INFLUENCES THE MOON IS AT THE FIRST QUARTER  
PHASE.  
 

 
   
ILM WATCHES/WARNINGS/ADVISORIES
 
 
SC...WIND ADVISORY FROM 10 AM TO 8 PM EDT MONDAY FOR SCZ054-056.  
NC...WIND ADVISORY FROM 1 PM MONDAY TO 5 AM EDT TUESDAY FOR NCZ106-  
108-110.  
MARINE...SMALL CRAFT ADVISORY FROM 1 AM TO 10 AM EDT MONDAY FOR AMZ250-  
252-254-256.  
GALE WARNING FROM 10 AM MONDAY TO NOON EDT TUESDAY FOR AMZ250-  
252-254-256.  
 

 
 

 
 
NEAR TERM...SRP  
SHORT TERM...SRP  
LONG TERM...RGZ  
AVIATION...SRP/CRM  
CLIMATE...TRA  
TIDES/COASTAL FLOODING...SRP  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab NC Page
The Nexlab SC Page Main Text Page