Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 252251 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 651 PM EDT Tue Sep 25 2018 .SYNOPSIS... Low pressure offshore will remain east of Cape Fear this evening before moving across the Outer Banks late tonight. Warm temperatures will prevail this week ahead of a slowly approaching cold front. The front will stall across the area Friday through the weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 700 PM Tuesday...Showers moved as far west as Lumberton, Fair Bluff, and Conway today in the broad outer envelope of a tropical disturbance centered about 100 miles southeast of Cape Fear. Reconnaissance aircraft flying through the disturbance this evening found a 1016 mb low and a closed circulation at the surface, but the system currently has insufficient convection to qualify as a tropical depression. The inland line of showers should die away over the next couple of hours, although I`m keeping a 20-30 PoP going from here to the coast through about 10 PM in case other showers develop within the conditionally unstable airmass and convergent low-level wind regime. Plenty of low-level moisture, gradually drying mid-levels, and light surface winds will set the stage for fog and/or low stratus clouds late tonight, particularly north of Florence, Marion, and Myrtle Beach. Guidance and persistence indicate conditions should begin to deteriorate around 5 AM. Very few changes were needed to the forecast this evening aside from updating the current location of the showers and clouds. Discussion from 300 PM follows... A weak frontal boundary was lingering near the Carolina coast as an area of disturbed weather associated with low pressure well off shore was moving westward toward the Cape Fear coast. This has produced a gusty NE flow across the area. Cu field was blanketing most of the area leaving breaks of sunshine this afternoon. Expect sunshine to continue to increase in spots, while showers continue to rotate around outer circulation of low pressure off shore, with most of them weakening or dissipating as they reach the coast. Dry air and subsidence further outside of low circulation will push inland limiting convection there. Intermittent lines or bands of showers will continue to move toward the Cape Fear coast northward. As these showers move on shore they could produce a brief period of gusty winds and heavy rain. Other showers were developing along convergence associated with weakening frontal boundary or sea breeze front in NE flow backing to the NW further inland. As the low off shore tracks toward the Cape Fear coast, it will come up against increasing mid to upper level SW flow which will help increase shear on the west side and help guide it up toward the north before it reaches the coast this evening into overnight tonight. Expect main convective activity to diminish by late evening as winds back further around to the W-SW with drier air and subsidence increasing over the area. Pcp water will basically run around 1.5 inches through the column overnight with only a slight chc of a shwrs over the adjacent coastal waters. Expect lows Wednesday morning between 70 to 75 most places. Ridge aloft will provide plenty of dry air and subsidence aloft on Wed. Any fog that develops early Wed morning will dissipate leaving just some cu around and with a westerly downslope flow, and subsidence aloft, expect plenty of sunshine and limited shwr activity with warm temps into the mid 80s. Mid to upper trough will push a cold front toward the Carolinas late Wed and moisture pooling out well ahead of the front in deep SW flow will produce some late aftn convection, but counting on much of the activity to remain west of local forecast area. Included lower end pops, mainly over I-95 corridor and west later Wed aftn, toward end of this period. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 300 PM Tuesday...a mid-level pressure trough will move over the eastern 2/3rd of the United States. At the surface a cold front will be in the central Carolinas and the 12 UTC NAM has it becoming stationary farther inland than the 12 UTC GFS which brings this boundary closer to the coast. What this front does is brings a ribbon of 2"+ precipitable water values over our area. With weak synoptic lift along the weak front, scattered showers and thunderstorms are possible through the forecast period and they may become more numerous on Thursday afternoon especially in the counties along Interstate 95. The latest QPF forecast calls for values of 0.50 to 1.00 inches between Wednesday night through Thursday night. Lows will be in the lower 70s inland to the middle 70s at the coast Wednesday night and Thursday night. The highs on Thursday will be in the middle 80s with a few upper 80s over the inland sections of northeast South Carolina. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 300 PM Tuesday...Front nearly stalled across the area Friday into Saturday; with just the slowest of southward drift. Both days will offer considerable rain chances though rainfall amounts do not appear high enough to worsen the ongoing river flooding (though crest recession may be slowed a bit). Thereafter mid level ridge builds overhead while surface high expands up and down the east coast and the area should trend towards drying. The building heights appear to offset the NE to E surface flow to keep temperatures near to a few degrees above climatology. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... As of 00Z...A tropical disturbance centered about 100 miles southeast of Cape Fear will move northward overnight, remaining well east of airports in our forecast area. Shallow moisture, drying mid-level conditions, and light surface winds will promote the development of fog and/or low stratus clouds late tonight. Persistence and latest model guidance indicate conditions should deteriorate around 09Z, with IFR conditions potentially lingering through 14-15Z Wednesday morning. Some afternoon thunderstorms are possible after 18Z Wednesday, but may be too isolated in coverage for inclusion in the forecast at this time. Extended Outlook...A cold front will slowly approach the region, with increased coverage of convection Thursday through Saturday. Morning fog possible each day. && .MARINE... NEAR TERM /THROUGH WEDNESDAY/... As of 700 PM Tuesday...Reconnaissance aircraft flying through the tropical disturbance centered about 100 miles southeast of Cape Fear this evening found a 1016 mb low and a closed circulation at the surface, but the system currently has insufficient convection to qualify as a tropical depression. Our coastal waters are well west of the low and will experience only mild northerly winds this evening, backing around more westerly after midnight as the low moves up toward the Outer Banks. Wind speeds should remain 15 knots or less. Seas 3-5 feet near and north of Cape Fear this evening are largely the result of the tropical disturbance. The Frying Pan Shoals buoy shows virtually all of the wave energy is embodied in an 8-second easterly swell. Seas should begin to diminish after midnight. Discussion from 300 PM follows... A weak front will continue to linger along the coast as low pressure treks toward the Cape Fear coast this evening. This has maintained a E to NE winds across the waters this afternoon 10 to 15 kts. As the low reaches the waters, it will turn northward toward Hatteras. This will shift winds around to the NW-W and eventually SW as it pulls farther off to the north through Wed. Winds should slowly diminish down to 10 kts through tonight. A few 5 fters in the outer waters north of Cape Fear will subside leaving all waters between 2 and 4 ft by morning. SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 300 PM Tuesday...with the tropical low moving north of the waters by Wednesday night and a frontal boundary stalling inland over the Carolina`s, the winds will be from the south to southwest through the period. The speeds will be around 10 to 15 knots through the period. Seas will be 2 to 3 feet south of Little River inlet Wednesday night and 2 to 4 feet to the north. Seas will be 3 to 4 feet through out of Thursday and Thursday night. LONG TERM /FRIDAY THROUGH SUNDAY/... As of 300 PM Tuesday...Southwesterly prefrontal winds will relax as the approaching boundary lightens the gradient. FROPA and the thus veering slated for Friday night. N to NE winds will then last for the remainder of the period. Seas will be slow to build and wave faces could steepen. Even so, conditions should remain below advisory thresholds. && .TIDES/COASTAL FLOODING... As of 300 PM Tuesday...Long fused coastal flood event on the Cape Fear river ongoing. High tides should just exceed warning level (6.7ft MLLW) as the flood wave moves down river combining with astronomical high tides. Please refer to any Coastal Flood Advisories or Coastal Flood Warnings for further details. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...Coastal Flood Warning until 2 AM EDT Thursday for NCZ107. MARINE...None. && $$ SYNOPSIS...MBB NEAR TERM...TRA/RGZ SHORT TERM...RH LONG TERM...MBB AVIATION...TRA TIDES/COASTAL FLOODING...RGZ is the U.S. government's official web portal to all federal, state and local government web resources and services.