Area Forecast Discussion
Issued by NWS Wilmington, NC

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476 FXUS62 KILM 190519 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1219 AM EST Sun Feb 19 2017 .SYNOPSIS... An upper level disturbance may bring a few light showers tonight. Warmer temperatures this weekend should last through next week. Dry weather during the first part of next week may be interrupted as low pressure passes to the south spreading some clouds and possible showers into the Carolinas late next week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... As of 930 PM Saturday...Precip on radar has almost completely dissipated over the past few hours. Where light rain was reported in ASOS/AWOS observations, only trace amounts fell. I`ll keep a small region of 20 PoPs in the forecast for late tonight with the approach of a vort max, now moving eastward across Georgia where some patchy light rain is breaking out near Atlanta. I`ve also added a little patchy fog across the Pee Dee region where light winds, clearing skies, and just enough boundary layer moisture may coexist just before sunrise Sunday. Discussion from 630 PM follows... Upper level low pressure located over southern Kentucky will weaken as it moves eastward tonight, ending up over Virginia by daybreak Sunday. Moving downward through the atmosphere...the low is still discernible at 700 mb but by the time you get to 850 mb there is very little perturbation left in the wind field. Low-level baroclinicity is naturally maximized near the Gulf Stream this time of year, and this is where surface low pressure should develop late tonight. Satellite and radar show a zone of clouds and light rain extending across the central Carolinas. ASOS cloud bases are generally 10kft where precip is falling. With surface dewpoints in the 30s and 40s I can`t imagine precip rates are going to become heavy enough for measurable amounts to occur. I`ve removed PoPs for this evening, anticipating only non-measurable sprinkles to fall across the Pee Dee region into Lumberton over the next few hours. What could turn out to be a slightly better potential for precip will develop late tonight as a 500 mb vort max currently over Mississippi moves east to the Carolina coast. Models show steepening lapse rates aloft as this feature (and the broader upper low) approach from the west. If low-level winds remain backed enough to maintain a ribbon of moisture along the coast, elevated convection could develop from bases around 6000-7000 feet AGL with tops in the 15000-20000 ft AGL range. I`ll keep a 20 PoP in the 08-11z timeframe along the coast for this potential and will continue to monitor model trends to judge how likely it is we need to keep this in the forecast. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... As of 300 PM Saturday...Time-height cross sections indicate rapid drying early Sunday as winds throughout the column shift quickly to the northwest. The mid-levels will remain quite dry through the period as a mid/upper ridge transitions from the central plains states on Sunday to the eastern seaboard by late Monday night. Mainly clear skies Sunday will start to become filtered by cirrus on Monday and through Monday night, but the period will remain precip- free. There will be some cool advection in the 1000-850 mb layer Sunday behind the front as low pressure strengthens offshore, and this should result in max temps a few degrees cooler than Saturday. As heights rise on Monday, temperatures should bounce a few degrees, though light onshore flow should keep them in check along the coast. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 300 PM Saturday...Medium range guidance continues to point to a very warm and mostly dry scenario for the eastern Carolinas through the period. Overall the mid level pattern is one of west to east with the exception of a closed mid level system trudging very far south through the Gulf of Mexico and out in the Caribbean. This system will have little to no affect on the region. Regarding surface features, high pressure to the north will be the dominant player with a weak coastal trough developing Wednesday and hanging around through Friday. This prevents the forecast from being totally dry with low chance to slight chance pops for these days. A more significant system approaches from the west next weekend. For temperatures its mostly highs in the 70s and lows in the 50s beyond a slightly cooler Tuesday. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... As of 06Z...An upper vort will try to rotate through the area, however the HRRR model keeps dissipating the precip as it tries to enter the CWA. Will keep the current VCSH in place with only a sprinkle possible. Will probably stay with a mid cloud ceiling at most sites. Some MVFR fog is possible after 08Z, confidence mod/low. Sunday, northwest flow on the backside of the surface low pressure, scattered skies. EXTENDED OUTLOOK...VFR conditions are expected. Chance of showers Wednesday and Thursday. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 930 PM Saturday...No significant changes are needed to the forecast at this time. Discussion from 630 PM follows... The 12z Canadian appears to be the winner with wind speeds this afternoon and this evening. Most of the other model guidance was several knots too weak versus observations from buoys, piers, and coastal airports. As weak low pressure develops off the coast tonight southwesterly winds should veer west, then northwesterly late. Seas are generally around 2 feet, although there is some potential for an area of 3 foot seas to develop south of Cape Fear this evening due to the 15 knot southwest winds that have been blowing across Long Bay for the past several hours. SHORT TERM/SUNDAY THROUGH MONDAY NIGHT/... As of 300 PM Saturday...Offshore flow Sunday will veer to the northeast Monday as a large area of high pressure extends southward across the Mid-Atlantic. Although low pressure will develop well off the SC coast Sunday, it will progress eastward rather quickly and the gradient winds across the coastal waters are expected to remain 15 knots or less through the period. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 300 PM Saturday...Expect northeast winds Tuesday on the order of 10-15 knots. By Wednesday the gradient weakens considerably with more of an east to southeast flow developing. The sea breeze will become more of a factor both Wednesday and Thursday. The weak gradient will only produce wind speeds of ten knots or less. Significant seas quite unimpressive through the period as would be expected with the light wind fields with 2-4 feet Tuesday followed by 1-3 feet Wednesday and Thursday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...SHK NEAR TERM...TRA SHORT TERM...CRM LONG TERM...SHK AVIATION...REK/DL MARINE...TRA/SHK/CRM

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