Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 101145 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 745 AM EDT THU JUL 10 2014 .SYNOPSIS... A COLD FRONT WILL STALL ACROSS THE REGION TONIGHT...PERSISTING INTO EARLY SATURDAY. THIS WILL BRING GOOD CHANCES FOR THUNDERSTORMS THE NEXT FEW DAYS...WITH PERIODS OF HEAVY RAINFALL. THIS FRONT WILL DISSIPATE LATE IN THE WEEKEND WITH A RETURN TO TYPICAL SUMMERTIME CONDITIONS...WITH A WARMING TREND DEVELOPING EARLY NEXT WEEK. ANOTHER COLD FRONT WILL APPROACH ON WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM THURSDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: THE LIKELIHOOD OF SHOWERS AND THUNDERSTORMS INCREASES TODAY AS THE ATMOSPHERIC COLUMN MOISTENS IN ADVANCE OF A SLOW MOVING COLD FRONT. MODEL SOUNDINGS SHOW THE COLUMN BECOMING NEARLY SATURATED WITH P/W VALUES IN THE 2 INCH RANGE BY THIS AFTERNOON. AT THE UPPER LEVELS A SERIES OF WEAK DISTURBANCES MOVING ALONG THE LEADING EDGE OF AN H/5 LONGWAVE TROUGH WILL ACT ON A MODERATELY UNSTABLE AND MOIST ATMOSPHERE TO KEEP IN THE THREAT OF CONVECTION...WITH THE POSSIBILITY OF HEAVY RAIN AND TRAINING STORMS THROUGH THE AFTERNOON AND EVENING HOURS. EXTENSIVE CLOUD COVER AND LOWERING THICKNESS VALUES WILL ALLOW FOR SIGNIFICANTLY LOWER DAYTIME TEMPERATURES THAN EXPERIENCED OVER THE PAST COUPLE OF DAYS...ESPECIALLY INLAND. EXPECT HIGHS OF AROUND 90 MOST PLACES...WITH UPPER 80S CLOSER TO THE COAST. MODEL CONSENSUS HAS FRONT STALLING OVER THE NORTHWESTERN PORTION OF OUR CWA OVERNIGHT. THE FRONT WILL SERVE AS A CONTINUED FOCUS FOR CONVECTION...SO WILL BE MAINTAINING LIKELY POPS WITH THE POSSIBILITY OF HEAVY RAIN FOR TONIGHT. CONSIDERING RECENT MODEL PERFORMANCE HAVE STAYED ON THE HIGH SIDE OF GUIDANCE FOR OVERNIGHT MINIMUMS. THIS WILL GIVE US LOWS IN THE LOWER TO MID 70S MOST PLACES. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 330 AM THURSDAY...FRIDAY CONTINUES TO LOOK VERY WET LOCALLY AS ELEMENTS COMBINE TO PRODUCE WIDESPREAD CONVECTION WITH HEAVY RAIN. AT THE SURFACE...A WEAKENING COLD FRONT WILL BE WAVERING ACROSS THE CWA...AND THIS...ALONG WITH REMNANT OUTFLOW BOUNDARIES FROM CONVECTION ON THURSDAY...WILL SERVE AS FOCI FOR UPDRAFTS ON FRIDAY. ALOFT...SHEAR LINE DEMARCATING THE LONGWAVE TROUGH AXIS WILL SWING OVERHEAD AND NORTHEAST DURING THE DAY...WHILE 300MB 100KT JET MOVES OVER NEW ENGLAND...LEAVING THE CAROLINAS WITHIN THE FAVORABLE RFQ DIFLUENT REGION...IN A SETUP THAT RESEMBLES QUITE WELL A MADDOX-TYPE EVENT FROM LITERATURE FOR HEAVY RAIN. ALL THIS OCCURS IN A THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY SBCAPE OF 800-1000 J/KG...PWATS OVER 2 INCHES...AND WARM CLOUD DEPTH APPROACHING 11 KFT. THE "LONG SKINNY" CAPE PROFILE SUGGESTS EFFICIENT PRECIPITATION PROCESSES (LONGER PARCEL RESIDENCE TIMES WITHIN STRONG COLLISION-COALESCENCE ENVIRONMENT) IN UPDRAFTS FRIDAY AS WELL...SO ALL SIGNS POINT TO A VERY ACTIVE DAY WITH HEAVY RAINFALL THE PRIMARY THREAT WITHIN THUNDERSTORMS. ALTHOUGH DRIER AIR WILL SLOWLY BEGIN TO FILTER INTO THE MID-LEVELS AS AN EMBEDDED SHORTWAVE PUSHES OFFSHORE LATE FRIDAY...STILL ANTICIPATE A SIGNIFICANT QPF DAY...HIGHEST EASTERN HALF OF THE CWA. TEMPS WILL BE TEMPERED BY THE WIDESPREAD CLOUDS AND RAIN...RISING ONLY INTO THE MID/UPR 80S. LOWS AT NIGHT WILL DROP INTO THE MID 70S AT THE COAST...BUT AROUND 70 WELL INLAND WHERE DRIER AIR WILL BECOME MORE PRONOUNCED LATE. SATURDAY WILL BE A TRANSITIONAL DAY AS RIDGING FROM THE SOUTHWEST TRIES TO BLOSSOM ACROSS THE AREA. IT WILL GET SHUNTED EAST BY THE AFOREMENTIONED LONGWAVE TROUGH...BUT THE WESTERLY FLOW BETWEEN THESE TWO FEATURES WILL HELP TO DRY THE COLUMN FROM FRIDAY. AT THE SAME TIME...THE SUBTLE THICKNESS INCREASE WILL HELP TO FURTHER ERODE THE FRONT WHICH SHOULD BECOME INDISTINGUISHABLE ON SATURDAY. HOWEVER...IT WILL CONTINUE TO HELP DRIVE CONVECTION...ALBEIT IN A LESS SIGNIFICANT MANNER THAN FRIDAY. STILL ANTICIPATE SCATTERED TSTMS SATURDAY AREA-WIDE...WITH TEMPS AGAIN JUST BELOW NORMAL IN THE UPR 80S TO AROUND 90...AND LOWS A FEW DEGREES ABOVE 70. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 330 AM THURSDAY...SEASONABLE CONDITIONS TO BEGIN THE PERIOD AS RIDGING DEVELOPS ALOFT AND HIGH PRESSURE OFFSHORE RIDGES BACK TOWARDS THE COAST. MID-LEVEL WESTERLY FLOW WILL CAUSE A RELATIVELY DRY COLUMN ON SUNDAY...SO ONLY ISOLATED CONVECTION IS ANTICIPATED...LIKELY LESS THAN CLIMATOLOGICALLY NORMAL. WITH HEIGHTS BUILDING ALOFT AND RETURN FLOW DEVELOPING...TEMPS SUNDAY WILL WARM TO SEASONABLE VALUES. THEREAFTER...HEAT WILL SLOWLY BUILD AGAIN THROUGH TUESDAY THANKS TO SUBTLE THICKNESS INCREASE DOWNSTREAM OF A LARGE TROUGH ACROSS THE MIDWEST...AND CONTINUED RETURN FLOW AT THE SURFACE. THIS DRIVES MORE TYPICAL CONVECTION CHANCES MONDAY/TUESDAY...BEFORE A COLD FRONT APPROACHES AND STALLS ACROSS THE AREA BY WEDNESDAY. THIS WILL BRING MUCH MORE WIDESPREAD PRECIP CHANCES FOR THE MIDDLE OF NEXT WEEK...ALONG WITH TEMPERATURES COOLING BACK TO SEASONABLE LEVELS. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 12Z...SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING NEAR THE COASTAL TERMINALS WITH GENERALLY MVFR CIGS AND S-SW WINDS 5-10KT. AT KFLO/KLBT CIGS ARE VFR WITH MVFR VSBYS IN BR AND LIGHT SE-S WINDS. EXPECT LITTLE CHANGE THROUGH MID MORNING EXCEPT VSBYS SHOULD INCREASE AT KFLO/KLBT AS BR BURNS OFF. BY LATE MORNING WINDS WILL INCREASE FROM THE S AT THE COASTAL TERMINALS. SHRA/TSRA SHOULD BECOME MORE LIKELY AT KFLO/KLBT AND LESS LIKELY AT THE COASTAL TERMINALS. DURING THE AFTERNOON THE BULK OF THE CONVECTION WILL AFFECT KFLO/KLBT...MOVING TO THE COASTAL TERMINALS IN THE EVENING. DUE TO UNCERTAINTIES IN TIMING AND COVERAGE WILL INDICATE MVFR CONDITIONS WITH CONVECTION. SHORT TERM IFR IS ALMOST CERTAIN TO OCCUR BUT SHOULD NOT LAST 15-30 MINUTES AT ANY ONE TERMINAL... UNLESS A TERMINAL HAPPENS TO BE UNDER TRAINING CELLS. CONVECTION BECOMES ISOLATED 06-12Z...MOST LIKELY AT KLBT AND NEAR THE COASTAL TERMINALS. MVFR VSBYS IN BR ARE ALMOST CERTAIN TO OCCUR 06-12Z AT KFLO/KLBT. CONFIDENCE OF IFR IS LOW DUE TO CLOUD COVER. EXTENDED OUTLOOK...A FRONT STALLS OVER THE REGION WITH A DECENT CHANCE FOR SHRA/TSRA THROUGH SATURDAY...MAINLY IN THE AFTERNOON. SHRA/TSRA ARE AGAIN POSSIBLE MONDAY. BRIEF IFR CONDITIONS ARE POSSIBLE IN THE HEAVIER SHOWERS AND STORMS. OTHERWISE VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM THURSDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: SOUTHWESTERLY FLOW WILL CONTINUE OVER THE WATERS THROUGH THE NEAR TERM AS HIGH PRESSURE OVER THE WESTERN ATLANTIC INTERACTS WITH AN APPROACHING COLD FRONT WELL INLAND. WINDS WILL STAY IN THE 10 TO 15 KT RANGE FOR MUCH OF THE PERIOD...WITH SEAS AVERAGING 2 TO 4 FT. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 330 AM THURSDAY...A WEAKENING COLD FRONT WILL WAVER IN THE VICINITY THROUGH SATURDAY...LIKELY REMAINING JUST WEST OF THE COASTAL WATERS DURING THIS PERIOD. THAT LEAVES A WEAK GRADIENT...AND S/SE WINDS FRIDAY AND SATURDAY AT 10 KTS OR LESS. LATE SATURDAY THE COLD FRONT WILL WASH OUT...AND AS HIGH PRESSURE BECOMES DOMINANT OFFSHORE...WINDS WILL VEER TO BECOME MORE SWLY...REMAINING AROUND 10 KTS. WAVE HEIGHTS WILL BE HIGHEST ON FRIDAY...THANKS TO WINDS EASING FROM THURSDAY...WITH 3-4 FT SEAS LIKELY ON A SOUTHERLY WIND CHOP. THESE HEIGHTS WILL DROP TO 1-3 FT ON SATURDAY ON THE LIGHTER WINDS. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 330 AM THURSDAY...MORE TYPICAL SUMMERTIME PATTERN WILL DEVELOP LATE IN THE WKND AND EARLY NEXT WEEK AS HIGH PRESSURE OFFSHORE EXERTS ITS INFLUENCE ACROSS THE COASTAL WATERS. SW WINDS WILL SLOWLY INCREASE THROUGH THE PERIOD...BECOMING 15-20 KTS LATE MONDAY. THE COMBINATION OF THESE RISING WINDS AND AN AMPLIFYING GROUND SWELL WILL DRIVE SEAS UP FROM 2-3 FT SUNDAY...TO 3-5 FT MONDAY...AND CAUTIONARY STATEMENTS MAY BE NEEDED EARLY NEXT WEEK. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...REK SHORT TERM...JDW LONG TERM...JDW AVIATION...MRR MARINE...REK/JDW

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