Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 231747 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 147 PM EDT SAT JUL 23 2016 .SYNOPSIS... A ridge of high pressure will expand across the Carolinas bringing increasingly hot and humid conditions through the weekend and much of next week. Isolated showers and thunderstorms are possible each afternoon, and heat advisories will likely be needed each day beginning Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 1000 AM Saturday...Admittedly surprised at the amount of convection this morning along the immediate eastern coast of the ILM CWA. Convection remains in a slowly weakening state, but several SMW`s and even some FLS`s have been issued due to strong storms drifting southward. WV imagery does not show any strong impulses, but there is a 50-60 kt upper jet off the coast into which the RRQ is above the local area. This increased diffluence is likely creating enough lift on residual outflow boundaries from last night to spawn and enhance the tstms across the coast and coastal waters. Fortunately, this jet will push south late this morning and upper diffluence will wane, bringing an end to this round of storms. However, these storms and their associated clouds will create a complex forecast this morning as they leave residual outflows and differential heating boundaries - both of which will likely serve as focus for tstms again this aftn during peak heating. However, clouds may linger long enough along the coast to affect the temperatures, and have dropped highs along the immediate coast back into the upper 80s, while maintaining low 90s inland. Humidity will be on the rise today, but enough dry mixing aloft will allow dewpoints to fall into the low 70s, which will keep heat indices just below the 105 threshold today, more in the 100-103 range. This will still serve as fuel for scattered aftn convection, and with PWATS about 0.25 inches higher on the morning soundings than yesterday, feel the HRRR/NSSL WRF depiction of more widespread sea breeze and piedmont trough will be correct and have schc/low chc pop this aftn/eve. Convection is forecast to wane once again diurnally, and do not see any forcing to drive tstms nocturnally, so have walked pop back to silent by midnight. Another warm night is forecast as Bermuda ridging and SW flow persists. Expect mins falling to a degree or two either side of 75. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 400 AM SATURDAY...A HOT AND HUMID AIRMASS WILL CONTINUE TO DOMINATE THE EASTERN CAROLINAS AS BROAD RIDGING PREVAILS ALOFT AND THE BERMUDA HIGH PERSISTS AT THE SURFACE. BOTH DAYS WILL FEATURE AFTERNOON HEAT INDEX VALUES EXCEEDING 100F, WITH A HEAT ADVISORY QUITE POSSIBLE FOR SUNDAY. MUCH LIKE ON SATURDAY, VERY DRY AIR ALOFT AND LACK OF STRONG FORCING WILL LIMIT CONVECTIVE COVERAGE TO ISOLATED STORMS EACH DAY, PRIMARILY ALONG THE SEA BREEZE FRONT AND ANY OTHER BOUNDRIES THAT HAPPEN BY. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 AM SATURDAY...OVERALL, BERMUDA HIGH AND PIEDMONT TROUGH WILL BE THE MAIN PLAYERS IN FORECAST MUCH OF THE WEEK. THEREFORE PERSISTENT S-SW WINDS WILL CONTINUE TO FEED WARM AND MOIST AIR INTO THE AREA WITH POTENTIAL FOR LOCALIZED SHWRS/TSTMS EACH DAY. THE UPPER RIDGE HELPING TO KEEP CONVECTION MORE LIMITED WILL BREAK DOWN A BIT INTO MID WEEK AS A NORTHERN STREAM TROUGH DIGS DOWN AS IT PUSHES A COLD FRONT SOUTH AND EAST. ALTHOUGH THE FRONT DOES NOT LOOK LIKE IT WILL MAKE IT, IT WILL DROP SOUTH INTO NORTH CAROLINA WHICH IN TURN MAY HELP TO INCREASE THE GRADIENT FLOW AND LOCALIZED CONVERGENCE AROUND THE BERMUDA HIGH AND PIEDMONT TROUGH INLAND. IT WILL ALSO TURN THE N-NE UPPER LEVEL FLOW AROUND THE EAST SIDE OF RIDGE EXTENDING INTO THE CAROLINAS FROM THE MIDWEST TO A MORE W-NW FLOW ALOFT, AROUND BASE OF STRETCHED OUT UPPER TROUGH EXTENDING DOWN FROM THE NORTH. SHOULD ALSO SEE A BIT MORE IN THE WAY OF CLOUDS AND CONVECTION REACHING INTO AREA FROM UPSTREAM. DO NOT EXPECT MUCH IN THE WAY OF UPPER LEVEL SUPPORT AS ATLANTIC RIDGE BUILDS QUICKLY BACK IN FROM THE EAST BY THURS/FRI. BY MID WEEK, THE INFLUENCE OF THE FRONT TO THE NORTH AND RETREAT OF RIDGE EXTENDING IN FROM THE MIDWEST SHOULD INCREASE CHC OF CONVECTION AND CLOUDS ACROSS THE AREA WHICH MAY SHAVE A FEW DEGREES OFF THE MAX TEMPS. BUT RIDGE BUILDS BACK IN FROM ATLANTIC AND OVERALL EXPECT VERY WARM TEMPS MOST OF THE WEEK. RIGHT NOW, IT LOOKS LIKE HEAT ADVISORY CONDITIONS MAY EXIST OVER SEVERAL DAYS NEXT WEEK. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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As of 18Z...Potential for MVFR in afternoon thunderstorms at KLBT and KFLO. Otherwise, expect VFR through the valid TAF period at all the terminals. Scattered showers and thunderstorms are expected to develop along the seabreeze and Piedmont trough as well as along residual outflow boundaries left over from morning convection. The high resolution models are showing the convection developing W of the coastal terminals with only slight movement to the S. Thus, will only include tempo for MVFR ceilings and visibilities at the inland terminals 18-21z. Winds may briefly gust to 25 kt or higher in slow moving thunderstorms, otherwise south winds will be 10 kt or less and up to 11 kt at KMYR and KCRE into early eve. EXTENDED OUTLOOK...Isolated to scattered afternoon convection Tuesday through Thursday may create periods of MVFR/IFR. Otherwise expect VFR.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1000 AM Saturday...Bermuda high will remain the dominant feature through tonight as it expands slowly from the Atlantic. The gradient will remain rather light, so SW winds will be only around 10 kts, rising to 10-15 kts tonight. A SE 9 sec swell will remain in the spectrum but in a slowly deamplifying manner, as a SW wind wave develops. Wave heights will remain at 2-3 ft through the near term, but develop a slightly lower average period tonight. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 400 AM SATURDAY...HIGH PRESSURE OVER THE WESTERN ATLANTIC WILL CONTINUE TO KEEP WINDS FROM THE SW AT 10 TO 15 KTS THROUGH MUCH OF THE THE PERIOD, WITH SEAS OF 2 OR 3 FT. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...SOUTH TO SOUTHWEST WINDS WILL CONTINUE AROUND THE BERMUDA HIGH. WINDS WILL GENERALLY STAY IN THE 10 TO 15 KT RANGE WITH A SLIGHT SPIKE IN LATE AFTN INTO EARLY EVE, ENHANCED BY THE SEA BREEZE AND PIEDMONT TROUGH. BY LATE WED GRADIENT WILL TIGHTEN AS COLD FRONT DROPS INTO NORTH CAROLINA. THIS SHOULD INCREASE WINDS AND SEAS WED NIGHT. OVERALL EXPECT SEAS 2 TO 3 FT BUT INCREASING SLIGHTLY THROUGH WED UP TO 3 TO 4 FT AND MAY SEE A FEW 5 FTERS IN OUTER WATERS IN STIFFER 15 TO 20 KT SW WINDS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...JDW SHORT TERM...REK LONG TERM...RGZ AVIATION...RJD is the U.S. government's official web portal to all federal, state and local government web resources and services.