Area Forecast Discussion
Issued by NWS Wilmington, NC

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569 FXUS62 KILM 222005 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 405 PM EDT SUN MAY 22 2016 .SYNOPSIS... An upper level low will move across the eastern Carolinas tonight and Monday bringing a chance for showers and thunderstorms. Upper level ridging will combine with Bermuda high pressure beginning Tuesday. Mainly dry weather and above normal temperatures will follow for the middle of the week through next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 300 PM Sunday...Based on latest 88D Mosaic reflectivity trends and vis satellite imagery, showers have developed within the CU field...mainly along and east of the I-95 corridor. And with additional insolation and an upper s/w trof passing overhead this aftn and early evening, the instability and dynamics should be enough for the showers to further develop into at least isolated convection. Have expanded the CU and POPs fields to cover the remainder of the ILM CWA. Temps aloft will slowly lower as the closed upper low drops further southward, closer to the ILM CWA. This will enhance the various lapse rates conducive for increasing instability. Model consensus places the cold core upper lows furthest southern extent across eastern NC by daybreak Mon. 500 mb temps by morning will have dropped from -14 degrees C early this aftn to -20 degrees C by daybreak Mon. With such cold temps aloft, pea size hail may accompany the convection this aftn and evening...and again late tonight. Another s/w mid-level trof rotating around the upper low is progged to partially push across portions of the FA late in the pre-dawn Mon hours. It is progged to exit the FA during the daylight Mon mid- morning hours. Models have been consistent with this scenario along with an ample supply of avbl moisture for cloud and pcpn development. The question resides, will there be enough instability to mention thunder during the pre-dawn Mon hrs. For now, have kept thunder out until daylight Mon where just enough insolation becomes avbl. Overall, afternoon Max and night-time lows will run 5 to 10 degrees below normal due to the effects from the upper low. With more cloudiness and threat of pcpn overnight, will tweak min temps upwards by a degree or 2, still keeping them within a consensus amongst the avbl model mos guidance. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...For Monday, avbl models are in a consensus with the evolution and now progression of the upper closed low. Initially on Monday, the upper low will be over the Eastern Carolinas. It`s progged to begin lifting northward with a slow acceleration during Monday, reaching off the NJ coast by daybreak Tue. As for sensible wx during Monday thru Monday night, one of the spokes or mid-level s/w trofs rotating around the closed low, will push across the FA Monday morning. The upper s/w trof dynamics, the cold temps aloft with -20 degrees at 500 mb Monday morning, and avbl moisture, will all combine to produce isolated to scattered convection, which will be continuing into this time period from the Near term Period. The morning`s insolation will likely be enough for instability early to mid daytime Mon morning to produce isolated thunder. With cold temps aloft, thunderstorms may produce pea size hail along with brief gusty winds. For the remainder of Monday and Monday night, subsidence aloft in the wake of the exiting s/w trof should keep a partial lid on any additional convection during Monday aftn and evening, but wouldn`t be surprised if a few convective cells develop. Temps thru Monday night will continue to run 5 to 10 degrees below normal. For Tuesday, the upper low will progress further ne, away from the ILM CWA, reaching off Cape Cod by daybreak Wed. As a result, the FA will be under a de-amplifying upper trof, and in addition, upper ridging will be approaching from the west by late Tue. The ILM CWA will no longer see those "spokes" rotating around the upper low moving across the FA. Drying thru the atm column will also be evident as illustrated by the latest various model rh time height displays for locations across the fa. All of this said, spells no POPs and a mostly sunny Tuesday and a clear sky Tue night. A warming trend will ensue, with Max/Min temps reaching normal levels. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 300 PM Sunday...Summer weather for the last week of May as ridging aloft and Bermuda high pressure at the surface combine across the southeast. Each day through the extended will feature above normal temps...widespread mid to upper 80s...although temps will be a bit cooler at the coast thanks to a sea breeze each aftn...with lows in the mid 60s. Subsidence beneath the ridge will preclude even diurnal convection most days...although will maintain a SCHC Thursday as a weak impulse moves atop the ridge...with enough subtle height falls and PVA to generate storms Thursday evening. Otherwise the forecast through the period remains dry and warm. On Sunday...both the ECM and GFS have a broad low pressure moving towards the coast embedded in the easterly flow. This could bring unsettled weather and cooler temperatures...however confidence is low and will keep pop below mentionable for D7. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... As of 18Z...IFR stratus has broken up leaving mainly MVFR/VFR conditions for this afternoon. A cold front will continue to drift farther off shore as a mid to upper low and associated cold pool aloft move into and across area tonight into Monday. This cold pool will produce some convection through this afternoon across the TAF sites but will dissipate into this evening. Light winds with mainly scattered skies will follow for tonight. Included a bit of MVFR fog for coastal terminals. Extended Outlook...Possible MVFR conditions on Monday, otherwise VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 300 PM Sunday...Cyclonic flow thru the atm column around the upper low dropping south, will result in nNW to N winds at 10 to occasionally 15 kt thruout this fcst period. Significant seas will hold around 3 ft for the waters from Cape Fear northward and 2 to 3 ft south of the Cape to South Santee River. A decent 1 to 2 foot ESEground swell at 8 to 9 second periods will primarily dominate thru tonight. The offshore nnw-n wind chop will become more evident the further away from the immediate coast 1 progresses. This wind chop will be limited in growth due to the offshore nature of the wind and resulting small fetch to grow. Showers and isolated storms may move off the mainland later this aftn and evening. A mid-level s/w trof will begin to push across the waters toward daybreak Mon, resulting with another bout of convection moving off the mainland during this time frame. isolated thunderstorms may accompany this pre-dawn Mon pcpn. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 pM Sunday...Surface Low off Cape Hatteras Monday morning will track to the north and eventually will get captured by the upper low also lifting to the north. A weakly tightened sfc pg initially will yield n winds backing to nw at 10 to occasionally 15 kt across the NC waters. With the captured low further departing Monday night thru Tuesday and weak high pressure settling across the area waters, winds will further back to the West Mon night into Tue, and SW late Tue into Tue night. The sfc pg will further relax yielding wind speeds around 10 kt at best. Significant seas will run basically be around 3 feet. Seas will subside from 2 to 3 ft at the start of Tue to around 2 ft Tue night. An ESE ground swell at 8 to occasionally 9 second periods will dominate the significant seas into Tue with locally produced wind waves becoming more evident during Tue thru Tue Night. Convection will be ongoing Monday morning. Any of the isolated thunderstorms that occur will be capable of producing brief wind gusts up to 25 kt, and even pea size hail along the immediate coast only. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS of 300 PM Sunday...Bermuda high pressure will dominate the synoptic regime through the end of the week. This drives persistent S/SW winds across the waters...and as the gradient remains light...speeds will peak around 10 kts each day. Seas within this regime will be rather uniform through the period...2-3 ft with a 2 ft/8 sec SE wave and 2 ft/4 sec SW wave comprising the spectrum. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...JDW NEAR TERM...DCH SHORT TERM...DCH LONG TERM...JDW AVIATION...RGZ MARINE...DCH/JDW

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