Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 290700 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 300 AM EDT WED JUL 29 2015 .SYNOPSIS... HIGH PRESSURE WILL SLOWLY WEAKEN THROUGH MID WEEK. A PIEDMONT TROUGH WILL FORM THIS AFTERNOON AND LINGER ON THURSDAY AS WEAK LOW PRESSURE REMAINS OFF THE SOUTHEAST COAST. A COLD FRONT WILL MOVE INTO THE AREA FRIDAY AND STALL DURING THE WEEKEND BEFORE FINALLY DISSIPATING ON MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 3 AM WEDNESDAY...VAPOR ANIMATIONS SHOW A DRY INTRUSION ALOFT PUSHING SOUTHWARD ACROSS THE MID-ATLANTIC INTO THE CAROLINAS EARLY THIS MORNING. TIME-HEIGHT ANALYSIS OF RH AND WIND TRAJECTORIES SHOW THIS DRY AIR EMBEDDED BETWEEN H5-H3 IN A 25-35 KT NORTH WIND FLOW. THIS ADVECTION WILL CAP LOCAL CHANCES OF PRECIPITATION FOR MOST AREAS TODAY. THE EXCEPTION AREA RESIDES MAINLY WEST OF I-95 WHERE THE STRONGEST LOW-LEVEL HEATING WILL OCCUR...AND CLOSEST IN PROXIMITY TO DYING DISTURBANCES ALOFT APPROACHING FROM THE NNW BUT EVEN THIS IS UNCERTAIN. MAXIMUMS TODAY 91-94 INLAND...AROUND 90 COASTAL INTERIOR AND UPPER 80S BEACHES AND ICW CORRIDOR. DIURNAL COOLING WHAT FEW SHOWER CROP UP LATER THIS AFTERNOON IN EVENING WITH A DRY LAYER ALOFT COVERING THE AREA. MINIMUM TEMPERATURES AT DAYBREAK THURSDAY LOW TO MID 70S INLAND AND UPPER 70S COAST. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 AM WEDNESDAY...PRECIP CHANCES WILL BE ON THE INCREASE DURING THE PERIOD AS 5H RIDGE BREAKS DOWN AND 5H TROUGH STARTS TO SET UP. ILL DEFINED SURFACE PATTERN ON THU WILL ALLOW SEA BREEZE AND PIEDMONT TROUGH CONVECTION BUT LACK OF SIGNIFICANT SURFACE OR MID LEVEL TRIGGERS WILL KEEP COVERAGE LIMITED. PRECIP CHANCES START TO INCREASE THU NIGHT AS WEAKENING COLD FRONT MOVES IN FROM THE NORTHWEST. FRONT ARRIVES AS INSTABILITY IS WANING WHICH SHOULD KEEP COVERAGE FOR THU NIGHT IN SLIGHT CHC RANGE AT MOST DESPITE THE PRESENCE OF LOW LEVEL CONVERGENCE AND DEEP MOISTURE. FRONT REMAINS IN THE AREA FRI...SERVING AS A FOCAL POINT FOR CONVECTION. DIURNAL INSTABILITY WILL HAVE PLENTY OF DEEP MOISTURE TO WORK WITH...PRECIPITABLE WATERS EXCEED 2 INCHES LATER IN THE DAY. WEAKENING SUBSIDENCE AND INSTABILITY ALONG WITH WHAT APPEARS TO BE SOME SLIGHT PVA FRI AFTERNOON INCREASES PRECIP CHANCES FRI INTO FRI NIGHT. WILL CONTINUE WITH INHERITED LIKELY POP BUT WONDER IF MID LEVEL RIDGING MIGHT HOLD ON A BIT LONGER THAN GUIDANCE IS SUGGESTING. SHOULD THAT BE THE CASE LINGERING SUBSIDENCE COULD KEEP CONVECTION IN CHECK...RESULTING IN SLIGHTLY LOWER POP THAN WHAT IS CURRENTLY FORECAST FOR THE SECOND HALF OF THE PERIOD. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 3 AM WEDNESDAY...STALLED FRONT AND DEEP MOISTURE LINGERS OVER THE AREA SAT KEEPING WEATHER UNSETTLED THROUGH THE WEEKS END. AT THIS POINT UNCERTAINTY IN THE FORECAST REALLY STARTS TO INCREASE. BOTH GFS AND ECMWF SHOW A 5H TROUGH DIGGING DOWN THE EAST COAST. MID LEVEL TROUGH PUSHES THE DEEP MOISTURE OFF THE COAST FOR THE START OF NEXT WEEK WITH THE REGION DRYING OUT. SURFACE PATTERN REMAINS ILL DEFINED AND WHATS LEFT OF THE SURFACE BOUNDARY WILL LINGER IN THE AREA. HOWEVER THE LACK OF DEEP MOISTURE KEEPS PRECIP CHANCES AT OR BELOW THE TYPICAL SUMMERTIME AFTERNOON 30 POP TO START THE WEEK. PREVIOUSLY GUIDANCE HAD BEEN SHOWING A STRONGER SHORTWAVE DROPPING ACROSS THE AREA IN THE DEEP NORTHWEST FLOW TUE. WHILE THIS FEATURE IS STILL DISCERNIBLE...JUST BARELY...IT IS IN A WEAKER STATE. AS THESE SHORTWAVES ARE FREQUENTLY CONVECTIVELY INDUCED/INFLUENCED WILL NOT GO ABOVE CLIMO POP FOR THE END OF THE PERIOD GIVEN THE HEIGHTENED UNCERTAINTY. TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE CLIMO...GENERALLY NEAR CLIMO BY DAY AND SLIGHTLY ABOVE BY NIGHT. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... AS OF 06Z...LITTLE CHANGE IN THE OVERALL PATTERN IS EXPECTED THIS TAF VALID PERIOD WITH HIGH PRESSURE N OF THE TERMINALS AND A LOW PRESSURE TROUGH OFFSHORE. WINDS WILL BE LIGHT NE-E...EXCEPT E-SE 6-12 KT AFTER SUNRISE INTO EARLY EVENING. SCT CU/SC 2-4K EXPECTED THROUGH THE PERIOD DUE TO A PERSISTENT LOW LEVEL ONSHORE FLOW. THERE IS A CONTINUED CHANCE OF FOG DEVELOPMENT EARLY THIS MORNING AS CLOUDS SCATTER. WILL INDICATE TEMPO MVFR VSBYS ATTM AT KFLO/KLBT BUT CONFIDENCE IS LOW SINCE THIS SAME PATTERN HAS YET TO YIELD FOG THE PAST SEVERAL MORNINGS. BUT THERE IS INCREASING CONFIDENCE OF LOW MVFR OR IFR CIGS DEVELOPING BY 10Z AT THE COASTAL TERMINALS. BEST CONFIDENCE OF ANY IFR WOULD BE AT KMYR. SOME SHOWERS MAY DEVELOP IN THE AFTERNOON BETWEEN THE INLAND AND COASTAL TERMINALS. EXTENDED OUTLOOK...PREDOMINANTLY VFR THROUGH THE PERIOD WITH A SLIGHT CHANCE AFTERNOON SHRA/TSRA. BEST CHANCE SHRA/TSRA FRIDAY AND SATURDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 AM WEDNESDAY...E WIND 10-15 KT TO PREVAIL TODAY AND TONIGHT...ACCOMPANIED BY 3-3.5 FOOT SEAS. SEAS PRIMARILY A MIX OF SE WAVES 2-3 FT EVERY 6 SECONDS AND MODERATELY EASTERLY CHOP. SHOWERS AND TSTMS ARE EXPECTED TO REMAIN WELL BEYOND THE 0-20 NM WATERS TODAY AND NO RESTRICTIONS TO VISIBILITY ARE EXPECTED. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 3 AM WEDNESDAY...ILL-DEFINED GRADIENT AND WEAK SURFACE WAVE PASSING EAST OF THE WATERS THU WILL INDUCE LIGHT NORTH TO NORTHEAST FLOW INTO THU NIGHT. WAVE MOVES OFF TO THE NORTHEAST THU NIGHT INTO FRI AS WEAK SURFACE FRONT DROPS IN FROM THE NORTHWEST. LIGHT AND VARIABLE WINDS THU NIGHT GAIN A SOUTHWEST COMPONENT FRI AND FRI NIGHT BUT LACK OF ANY REAL GRADIENT KEEPS SPEEDS AROUND 10 KT THROUGH THE END OF THE PERIOD. SEAS 2 TO 3 FT THROUGH THE PERIOD. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 3 AM WEDNESDAY...SOUTHWEST FLOW WILL CONTINUE OVER THE WATERS THROUGH THE WEEKEND. THE REMAINS OF A STALLED FRONT WILL LINGER NEAR THE COAST AS BERMUDA HIGH TRIES TO BUILD BACK WEST. GRADIENT WILL REMAIN ON THE WEAK SIDE WITH SPEEDS NO MORE THAN 10 TO 15 KT AT ANY POINT DURING THE PERIOD. DAILY SEA BREEZE WILL RESULT IN ENHANCED ONSHORE FLOW NEAR THE COAST BOTH DAYS. SEAS WILL RUN 2 TO 3 FT ON SAT AND 2 TO 4 FT SUN. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...8 SHORT TERM...III LONG TERM...III AVIATION...MRR/8

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