Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 182328 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 728 PM EDT Sat Mar 18 2017 .SYNOPSIS... A cold front will push through tonight and bring some drier air into the area Sunday and Monday. The upcoming week will feature a gradual warmup until the next front arrives Tuesday night or Wednesday. && .NEAR TERM /THROUGH SUNDAY/...
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As of 645 PM Saturday...Have upped the thunderstorm threat mainly for the ILM NC CWA thru this evening. Latest meso-analysis indicates the threat for convection well into the evening hrs. Instability was in question earlier due to lack of insolation but apparently enough, just shy of 1000 CAPE, to support convection let alone strong to isolated severe possibilities. Dynamics aloft in the form of a mid-level s/w trof or potent vort across central NC at the moment, will lift NE away from the ILM CWA later this evening. Will continue the threat for isolated severe for the ILM NC Counties this evening which is now stated in the updated HWO. Previous..................................................... As of 300 PM Saturday...The latest surface observations indicate the cold front is now moving into Western North Carolina. This front will continue to move south and east this afternoon and evening. The mostly mid level induced rainfall is now moving out of the CWA. The forecast challenge is the extent a decent shortwave aligned mostly with the front cranks up another round of showers this evening. Regional radar loops show activity increasing in Eastern Tennessee with even a little lightning in the mix. The forecast shows the lull in pops this afternoon with increasing values in the evening. I also increased overnight lows in respect to recent guidance which has warmed also. Expect very gusty condiitons Sunday under mostly sunny skies.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 300 PM Saturday...An easing gradient Sunday night as high pressure builds in will allow for wind to eventually go near calm. Temperatures will radiate 5-8 degrees below climatology, getting into the upper 30s in most areas. Downsloping NW mid level flow and surface high to our south will bring a sunny and near seasonable day Monday. Increasing surface moisture and cloud cover will keep Monday night very mild with lows near 50. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 300 AM Saturday...The next cold front should arrive in the Carolinas Tuesday evening, sinking south across our area overnight. A weak wave of low pressure moving eastward along the front won`t intensify significantly until it reaches the ocean and begins to feed on the better low-level baroclinicity present there. There is a good deal of difference in timing between the GFS which is faster with the frontal passage and farther south with the low versus the slower/more northern ECMWF. Should either model verify the better shower chances with the front should exist across North Carolina, with generally drier mid- level air across South Carolina limiting rainfall potential there. I have even put the potential of some thunder in the forecast Tuesday evening as there should be small elevated instability coupled with reasonably strong dynamics aloft. PoPs have been raised to 40-60 percent across SE North Carolina, lesser changes to the south. Another cool to cold airmass should follow this system for Wednesday and Thursday. The new 00z ECWMF is quite a bit colder than the 00z GFS and much cooler than our previous forecast. It`s worth mentioning that if this ECMWF solution verifies it could create one or two nights (Wed and Thu nights) with the risk of frost. Our latest forecast has cooled down by about 5-7 degrees versus 12 hours ago for the nighttime lows Wed and Thu, but we`re still closer to the warmer GFS. A moderating trend should develop by Friday. && .AVIATION /23Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...Expect mostly VFR conditions through the period. There is a low chance of MVFR ceilings with some residual moisture this afternoon and once again early this evening with a final weak shortwave and more rainfall. Beyond this expect another round of strong cold air advection through the lower levels which will increase the winds. Expect very strong gusts Sunday starting mid morning especially along the coastal terminals lasting through the early afternoon hours. Extended outlook...Expect VFR thru the period except possible MVFR with isolated IFR conditions from ceilings and pcpn ahead of the next cold frontal passage late Tuesday. && .MARINE... NEAR TERM /THROUGH SUNDAY/... As of 300 PM Saturday...Winds and seas are elevated this afternoon with 41013 hovering around seven feet with southwest winds in a 20-25 knot range. These condiitons will persist through the afternoon and evening hours. A cold front will move across the waters around midnight with winds shifting to the northwest. Speeds remain elevated and even increase Sunday morning to 25-30 knots sustained with some gusts into gale criteria. Small craft condiitons remain through Sunday. SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 300 PM Saturday...As of 300 PM Saturday...As high pressure builds to our west the local pressure gradient and resulting winds will ease as Sunday night progresses. AS they lighten to 10kt or less on Monday they will also back in direction as the center of the high winds up to our south. By Monday night they will have turned to the SW and pick up a few knots in speed as a frontal boundary slowly approaches from the north. LONG TERM /TUESDAY THROUGH WEDNESDAY/... As of 300 AM Saturday...Another cold front will approach from the north Tuesday afternoon, reaching the Carolinas Tuesday night. A wave of low pressure trickling eastward along the front from Tennessee should intensify as it reaches the Carolina coast Tuesday night. As soon as the low moves offshore there should be a surge of northerly winds developing late Tuesday night into Wednesday. Models are not completely in agreement with the timing or strength of this feature. Most notably, this morning`s new ECMWF model is 6-9 hours slower and is also considerably farther north with the low which delays the timing of the surge and attenuates its strength this far south. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until 3 PM EDT Sunday for AMZ250-252-254- 256. && $$ SYNOPSIS...MBB NEAR TERM...DCH/SHK SHORT TERM...MBB LONG TERM...TRA AVIATION...SHK MARINE...TRA is the U.S. government's official web portal to all federal, state and local government web resources and services.