Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 220230 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 930 PM EST Tue Feb 21 2017 .SYNOPSIS... Temperatures will remain well above normal this week. A week trough may bring spotty showers to the region Wednesday and Thursday. Near record highs are possible Friday. A cold front, approaching from the west, will bring a slight chance of showers Saturday. Much cooler and drier air will build into the area Saturday night into early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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As of 9 PM Tuesday...Closed upper low and surface reflection over the Mid-South and Gulf Coast states will drift southeast overnight, while surface high pressure off the New England coast drops south. 00Z soundings from MHX and CHS reveal a dry airmass from about 850 mb up to 400 mb. However high cloud cover will be extensive overnight, and low-level moisture will continue to increase in onshore flow. Few adjustments needed to forecast this period, however have adjusted temps up a tad as they are falling a little slower. As a result, the dewpoint depression is not as supportive for fog development, so forecast coverage has been trimmed back.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... As of 3 PM Tuesday...The center of high pressure Wed will be offshore of the Mid-Atlantic states and will drift further offshore as it ridges back across the eastern Carolinas through Thu night. At the same time, slow moving low pressure will be vertically stacked as it moves across the Florida peninsula and Bahamas. Still looks like there will be too much dry air to support showers on Wed. Yet there will be some shortwave energy migrating from W to E across the area, so hard to rule out an isolated shower although all the guidance has backed off on any showers across the Forecast Area Wed and Wed eve. Therefore, since we can not rule a shower out, will leave the smallest of POPs in the forecast Wed afternoon and early eve. Model soundings and moisture profiles support the development of late night fog late Wed night. Columnar moisture is a little greater Thu, but there are no obvious triggers and transport of deeper moisture to our S will be cutoff by the large circulation center across FL and the Bahamas. Will include a small POP as the seabreeze may provide sufficient lift to support shallow showers. Any afternoon showers Thu should quickly dissipate early in the eve with loss of heating. Highs will be mainly in the mid 70s away from the cooling impacts of the ocean both days, with Thu likely slightly warmer. Near and along the immediate coast, highs will be in the upper 60s to around 70 with lower to mid 60s at the beaches. Lows will be in the mid and upper 50s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 3 PM Tuesday...Period begins with the forecast area between filling 5h low off the east coast of FL and high amplitude 5h trough moving east across the center of the country. Although a strong cold front will move across the area late Sat there is unlikely to be much in the way of convection along the front. The environment ahead of the front is very dry, due to a combination of limited moisture return and strong mid level subsidence. Cannot rule out a few isolated showers but do not feel anything more than a slight chc/silent pop is warranted. Despite low level northeast to east flow ahead of the front Fri into Sat, as a weak surface low passes well off the coast, temperatures will be well above climo with highs approaching 80 each day and lows in the 50s. Sat could end up slightly warmer than Fri as low level flow becomes southwest once the low exits northeast. Following the passage of the front, 850 temps drop as much as 12C. Despite the impressive drop, temperatures Sun will be right around climo. Mid level trough exits Mon and warm advection begins as the surface high shifts off the coast and pattern aloft becomes progressive. Temperatures will jump back above climo Mon, remaining above climo through the end of the period. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... As of 00Z...Patchy areas of MVFR fog possible late overnight into the early morning hours. Otherwise expect VFR. Widespread cirrus cigs along with SCT/BKN mid clouds continue to move across the area this evening, with easterly winds around 5 kts or less. Expect this trend to continue overnight, with latest guidance continuing to suggest the potential for areas of MVFR due to fog to develop late overnight. After daybreak on Wednesday, expect any fog to disperse, giving way to VFR through the rest of the valid TAF period. East- southeasterly winds will increase to 5 to 10 kts throughout the day, with BKN/OVC mid to high clouds expected. Extended Outlook...Isolated showers late Wednesday through Thursday. Showers possible Saturday with a cold front. Otherwise expect VFR. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 9 PM Tuesday...E to ESE winds will prevail tonight as high pressure drifts south along the Mid-Atlantic coast. Wind speeds will be 10 to 15 kt most of the time. Seas will remain 2 to 3 ft. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 3 PM Tuesday...The center of surface high pressure along the Mid-Atlantic coast Wed will drift further offshore as it ridges back across the Carolina waters through Thu night. A vertically stacked area of low pressure will slowly move across FL and the Bahamas during the period. This will tighten the pressure gradient to our S. The wind direction will be mainly E or ESE Wed through Thu with a tendency to back slightly Thu night. Wind speeds during this forecast period will be no higher than 10 to 15 kt. Seas will build gradually, reaching 3 to 4 ft Wed and Wed night and 3 to 5 ft Thu. Small Craft Advisory seas may develop Thu night, from S to N, as seas build to 4 to 6 ft. LONG TERM /FRIDAY THROUGH SUNDAY/... As of 3 PM Tuesday...Weak low pressure moving northeast, well off the coast, and weak high to the west will both contribute to northeast flow around 10 kt Fri into Sat. Winds back to southwest Sat as the low exits and front approaches from the west. Pinched gradient ahead of the front may lead to speeds in excess of 20 kt late Sat into Sat night. Offshore flow behind the front will remain a solid 20 kt, possibly bumping 25 kt early Sun, with cold advection developing. Offshore flow continues Sun but weakens during the day as both gradient and cold advection relax. Seas well away from shore will flirt with 6 ft for at least the first half of the period, a mix of wind wave and swell. Swell component decreases Sat and Sun while the wind component increases a bit Sat before offshore flow Sun knocks seas within 20 nm down for the later half of the period. Headlines will likely be required for Fri and Sat but have low confidence as to which headline will be needed.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ NEAR TERM...RJD/CRM SHORT TERM...RJD LONG TERM...III AVIATION...SGL

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