Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 211922 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 320 PM EDT MON JUL 21 2014 .SYNOPSIS... A STATIONARY FRONT STALLED ACROSS THE INTERIOR CAROLINAS WILL SLOWLY DISSIPATE TONIGHT AND TUESDAY. BERMUDA HIGH PRESSURE WILL BUILD INTO THE AREA WEDNESDAY AND THURSDAY. A COLD FRONT WILL APPROACH FROM THE NORTHWEST LATE IN THE WEEK AND STALL NORTH OF THE AREA FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM MONDAY...THIS IS CERTAINLY AN ATYPICAL SUMMER WEATHER PATTERN ACROSS THE CAROLINAS. AN UPPER LEVEL LOW ACROSS WESTERN GEORGIA AND THE UPPER CENTER OF THE BERMUDA RIDGE WELL OFFSHORE ARE DIRECTING A STREAM OF RICH TROPICAL MOISTURE NORTH ACROSS THE AREA. PRECIPITABLE WATER VALUES ARE IN EXCESS OF 2.1 INCHES WITH THIS MORNING`S 12Z CHS SOUNDING SHOWING 2.23 INCHES...NEAR THE 95TH PERCENTILE FOR JULY. A STATIONARY FRONT WAS RATHER DIFFUSE EARLY THIS MORNING BUT HAS BECOME RENEWED BY COOL CONVECTIVE OUTFLOW AND IS NOW LOCATED FROM NEAR CAPE FEAR TO CONWAY TO SOUTHERN FLORENCE COUNTY. THIS HAS BEEN THE FOCUS FOR NEW CONVECTIVE DEVELOPMENT WITH THE ENVIRONMENTAL SOUTH FLOW ADVECTING RAIN BACK OVER THE COLD DOME. THIS WILL PROBABLY CONTINUE FOR THE NEXT FEW HOURS UNTIL INSTABILITY GETS USED UP. HEAVY RAIN HAS BEEN THE BIG STORY TODAY. RADAR ESTIMATED TOTALS HAVE REACHED 4+ INCHES NEAR WILMINGTON...JUST NORTH OF CONWAY...AND ACROSS NE FLORENCE COUNTY INTO CENTRAL DILLON COUNTY. FLOODING REPORTS HAVE SO FAR BEEN OF THE MINOR VARIETY BUT THAT MAY CHANGE AS TOTALS CONTINUE TO INCREASE. THE ONLY INGREDIENT MISSING FOR A MORE WIDESPREAD FLOOD EVENT IS STRONGER 5000-10000 FOOT WIND SPEEDS. WINDS ARE GENERALLY LESS THAN 10 KNOTS THROUGH THIS LAYER. CONSIDERABLE CONVECTIVE DEBRIS CLOUDINESS IN THE EVENING WILL SLOWLY DECAY OVERNIGHT...ALTHOUGH ANY SIGNIFICANT CLEARING WILL PROBABLY JUST RESULT IN THE DEVELOPMENT OF LOW STRATUS JUST OFF THE SURFACE. LOWS SHOULD FALL INTO THE 70-73 DEGREE RANGE...WARMEST AT THE BEACHES. RECORD RAINFALL TOTALS FOR TODAY: WILMINGTON 3.84 INCHES IN 1939 (2.48 INCHES TODAY AS OF 315 PM) FLORENCE 1.70 INCHES IN 1995 (1.14 INCHES TODAY AS OF 315 PM) && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...DEEP MOISTURE SHOULD CONTINUE TO BE CHANNELED INTO THE COASTAL CAROLINAS ON TUESDAY. DEEPENING UPPER LOW TO OUR WEST WILL BE RETROGRADING SLIGHTLY WHILE RIDGE OFFSHORE BUILDS SLIGHTLY. MODELS SHOW LONG FETCH SOUTHERLY FLOW AT THE SURFACE WITH A COASTAL TROUGH EARLY IN THE DAY THAT MIGRATES INLAND AS THE DAY WEARS ON. THE WRF IN PARTICULAR IMPLIES THAT CONVECTIVE COVERAGE AND QPF PROSPECTS MAY MIRROR THOSE OF TODAY WITH FORECAST PRECIPITABLE WATERS STAYING AS ELEVATED AS THEY ARE NOW OR EVEN INCREASING SLIGHTLY TO 2.25" AND ALTHOUGH THE STRONGER MID LEVEL VORTS PORTRAYED IN THE WRF HAVE THE LOOK OF CONVECTIVE FEEDBACK ANALYSIS OF LOW LEVEL POTENTIAL VORTICITY FIELDS SHOW NO SPURIOUS DATA TO INDICATE SUCH. WEDNESDAY IS A BIT OF A TRANSITIONAL DAY...BUT COULD READILY SEE HOW THE AFTERNOON OFFERS UP HIGHER THAN NORMAL COVERAGE OF STORMS ALBEIT LESSER THAN TODAY/TUESDAY. THE MAIN UPPER LOW TO OUR WEST CONTINUES TO RETROGRADE BUT WE STILL HAVE A MID LEVEL SOUTHERLY COMPONENT...USUALLY A GOOD INDICATOR FOR AN ACTIVE DAY...ESPECIALLY WITH LITTLE IMPETUS FOR LOW LEVELS TO DRY OUT MUCH. && .LONG TERM /THURSDAY THROUGH MONDAY/.... AS OF 300 PM MONDAY...LONGWAVE TROUGH EXPANDING ACROSS THE EAST WILL CAPTURE A RETROGRADING CLOSED 500MB LOW OVER THE GULF COAST LATE IN THE WEEK...AND SWING IT BACK TO THE NORTHEAST. THIS WILL LEAVE BROAD TROUGHING ACROSS THE EAST THROUGH THE WKND. BENEATH THIS TROUGH...A COLD FRONT WILL DROP SLOWLY SOUTHEAST...REPLACING THE HIGH PRESSURE RIDGE THAT WILL BE OVER THE AREA FROM MID-WEEK. WITH STRONG MOIST ADVECTION AHEAD OF THIS BOUNDARY...AND WAVES OF LOW PRESSURE EXPECTED TO DEVELOP ALONG IT...THU/FRI SHOULD ONCE AGAIN FEATURE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS...WITH TEMPS AROUND CLIMO BOTH DAYS. THE COLD FRONT DRIFTS OFFSHORE FOR THE WKND...LEAVING A DRIER COLUMN...BUT STILL TYPICAL SUMMERTIME CONVECTION CHANCES AND TEMPS JUST BELOW NORMAL. BEYOND THE WEEKEND DURING EARLY NEXT WEEK...SIGNALS POINT TO A STRONG RE-AMPLIFICATION OF THE MID-LEVEL PATTERN WITH AN ANOMALOUSLY DEEP TROUGH ACROSS THE EAST. THIS COULD BRING A RENEWED PERIOD OF BELOW NORMAL TEMPS AND ABOVE NORMAL PRECIP CHANCES BEGINNING MONDAY. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... AS OF 18Z...WITH PRECIPITABLE WATER AMOUNTS OVER TWO INCHES AND INSTABILITY AS HIGH AS 2500 J/KG...LOOK FOR CONVECTION WITH HEAVY RAIN TO FIRE ALL AFTERNOON AND A BIT INTO THE EVENING HOURS. THINGS WILL BEGIN TO CALM DOWN BY 02Z AS INSTABILITY DROPS OFF SIGNIFICANTLY. WITH ALL THE HEAVY RAIN...FOG IS A POSSIBILITY... HOWEVER CONVECTIVE DEBRIS CLOUDINESS SHOULD KEEP IT AT MVFR. MVFR CEILINGS ARE ALSO LIKELY GIVEN THE REMAINING LOW LEVEL MOISTURE. TUESDAY...ANOTHER ROUND OF CONVECTION MUCH LIKE TODAY...BEGINNING FAIRLY EARLY DUE TO LARGE MOISTURE VALUES AND NO CAPPING INVERSION ALOFT. EXTENDED OUTLOOK...CHANCE OF SHOWERS/TSTMS PERSISTS THROUGH THE EXTENDED FRIDAY. EXPECT PREDOMINANTLY VFR CONDITIONS WITH BRIEF PERIODS OF MVFR CIGS/VSBYS IN STORMS. VFR SATURDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM MONDAY...A STATIONARY FRONT HAS BEEN RENEWED BY A LARGE AREA OF SHOWER AND THUNDERSTORM ACTIVITY NORTH OF CAPE FEAR AND INLAND...AND THE BOUNDARY APPEARS TO LIE ALONG THE COAST OF BRUNSWICK COUNTY AT THE TIME OF THIS WRITING. EAST-NORTHEAST WINDS NORTH OF THE FRONT CONTRAST WITH A MORE SOUTHEASTERLY FLOW DOWN TO THE SOUTH. THE BOUNDARY IS EXPECTED TO SINK SOUTH THROUGH THE GRAND STRAND LATER THIS EVENING WITH A GENERALLY EAST-NORTHEAST WIND THROUGH THE OVERNIGHT HOURS. OUTSIDE OF THUNDERSTORMS WINDS SHOULD AVERAGE 10 KNOTS OR LESS...ALTHOUGH WE SEE WINDS GUSTING AS HIGH AS 15-20 KNOTS CURRENTLY AT WRIGHTSVILLE BEACH AND SOUTHPORT DUE TO THUNDERSTORM ACTIVITY IN THE AREA. SEAS CONSIST LARGELY OF A SOUTHEASTERLY 7-8 SECOND SWELL...WITH A NORTHEAST CHOP ON TOP NORTH OF CAPE FEAR. COMBINED SEAS ARE AVERAGING 3 FEET WITH SOME 2-FOOTERS NEAR SHORE SOUTH OF CAPE FEAR. LITTLE CHANGE IS ANTICIPATED THROUGH THE NIGHT. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...TUESDAY BRINGS A PREDOMINANTLY SOUTHEASTERLY WIND AS A SURFACE TROUGH INITIALLY NEAR THE COAST MOVES INLAND WHILE WEST ATLANTIC HIGH PRESSURE REMAINS NEARLY STATIONARY. SPECTRAL WAVE BULLETINS SHOW THAT A GENERAL 3 FT DOMINANT SEA STATE TO BE A NEARLY SINGULAR 7 SECOND WAVE SET. A MORE TYPICAL PIEDMONT TROUGH SETS UP ON THURSDAY AND THE ATLANTIC HIGH DOES APPEAR TO FLEX WESTWARD CLOSER TO THE COAST A BIT. THIS SHOULD BE GOOD FOR ABOUT A 5KT INCREASE IN THE RANGE OF WAVE HEIGHTS AND SHOULD INTRODUCE A 4 FT WIND WAVE TO MOST ZONES. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 300 PM MONDAY...PINCHED GRADIENT BETWEEN OFFSHORE HIGH PRESSURE AND A SLOWLY APPROACHING COLD FRONT FROM THE NW WILL DRIVE SW WINDS UP TO 15-20 KTS THURSDAY AND MUCH OF FRIDAY. THIS FRONT IS EXPECTED TO CROSS OVER THE WATERS VERY LATE FRIDAY WITH A WIND SHIFT TO THE WEST...AND A SPEED REDUCTION TO LESS THAN 10 KTS. THIS WILL BE SHORT LIVED HOWEVER...AS THE FRONT PUSHES BACK TO THE NORTH BY THE END OF THE PERIOD WITH A RETURN OF SW WINDS. SEAS THU/FRI WILL RISE TO 4-5 FT AT TIMES THANKS TO THESE STRONGER WINDS AND A SE GROUND SWELL...AND CAUTIONARY STATEMENTS MAY BE REQUIRED. THE WATERS WILL FEATURE LOWER AMPLITUDE SEAS ON SATURDAY OF 2-3 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...HIGH RIP CURRENT RISK THROUGH THIS EVENING FOR NCZ106-108. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...MBB LONG TERM...JDW AVIATION...43/TRA

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