Area Forecast Discussion
Issued by NWS Wilmington, NC

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696 FXUS62 KILM 240049 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 849 PM EDT Mon Oct 23 2017 .SYNOPSIS... A strong cold front will approach from the west today and slow, finally moving completely offshore Tuesday afternoon. Showers and thunderstorms are expected along and ahead of the front with the possibility for a line of strong to severe thunderstorms this evening and tonight. In the wake of the front, dry and cool air is expected through Thursday as Canadian high pressure takes hold. A warming trend begins Friday. Shower chances increase Saturday as a weak area of low pressure develops ahead of a second cold front. && .NEAR TERM /THROUGH TUESDAY/...
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As of 830 PM Monday...Axis of surface-based instability was moving eastward across the Pee Dee region as of 00Z, with LI`s of -2C to -3C extending from near LBT southward through Kingstree. Modest surface pressure falls were occurring just east of this axis of instability, and will transition eastward and off the coast over the next few hours. Although backing of the surface winds in response to these pressure falls has been modest across the CWA, the shear profiles as evidenced by KLTX VWP will remain conducive for storm rotation through the remainder of the evening. Latest HRRR indicates the thunderstorm activity will move off the coast around 06-07Z. Cool advection lags considerably behind the wind-shift though dewpoints may start dropping Tuesday afternoon temperatures will still warm up into the upper 70s, a solid category above climatology.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM Monday...Very quiet conditions will settle into the area as a deep full latitude mid level trough moves from the Tennessee Valley to just offshore through the period. Precipitable waters dip to near one quarter of an inch by late in the period. At the surface a somewhat blustery pressure gradient will reside across the area and this is reflected n the guidance. There may be some decoupling early Thursday morning allowing temperatures to possibly drop to the coolest readings of the season in some areas with lower to mid 40s area wide. && .LONG TERM /THURSDAY THROUGH MONDAY/... As of 300 PM Monday...Very cool temperatures start the extended as Canadian high pressure settles across the area before pushing offshore Friday. Temps Thursday will likely be about 5 degrees below climo before recovering to more seasonable temps Friday as the surface high shifts offshore. Moisture will begin to increase Saturday on increasing southerly winds as a pre-frontal airmass returns ahead of a deep mid-level trough pushing through the MS VLY. This will drive a cold front across the area Saturday night into Sunday. Ahead of this feature, a weak area of low pressure may develop and move just off the coast, and while total column moisture remains confined below 700mb, showers are possible late Saturday through Sunday morning associated with this feature. This front will bring the potential for the coldest air of the season behind it, as 850mb progs drop below 0C and extended MOS numbers feature values as much as 10 degrees below climo early next week. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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As of 23Z...Latest radar showing precipitation moving up the SC coast soon to impact KMYR and KCRE. Light rain already at KFLO and KLBT with nothing yet at KILM. Forecast for the overnight period still a bit tricky with VAD wind profile showing some veering between 8k and 17k with 35 to 45 kt winds. As front pushes to the east storm motion is moving all cells to the NE at greater than 30 mph. Impacts will affect all terminals through the evening/overnight period with high confidence in MVFR and possible IFR conditions in vsby and ceiling. Have mentioned tstm across the inland terminals but not to confident at the coastal terminals although cannot totally ruled out but will not mention at terminals. Gusty SSE to S winds will prevail overnight until FROPA and will mention low ceilings and vsby across KLBT and KFLO with fog as winds abate behind the front. Weather will improve from west to east across the terminals. Concern might be for some wind shear around 03z near the coast but will keep an eye on this as VAD winds are pretty uniform with the wind speeds from the sfc up to about 4-5K. main concern for all terminals will be between 00Z and 06Z before condition slowly improve. After 25/15z VFR conditions across the region. Extended Outlook... VFR Wednesday through Friday. Slight chance for showers Saturday.
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&& .MARINE...
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NEAR TERM /THROUGH TUESDAY/... As of 830 PM Monday...Latest buoy obs are indicating strong southerly winds across the waters, with gusts of 25-30 knots. Seas at buoy 41013 were running near 8 feet. Latest guidance suggests winds will diminish late tonight across the SC waters, and early Tuesday morning north of Cape Fear. Seas will subside below SCA thresholds beginning early Tuesday south of Little River Inlet, and by early afternoon across the waters north of Little River Inlet in the wake of the wind shift. Won`t make changes to the SCA at this time, but if this timing expectation holds, we may be able to remove the southern waters from the SCA a little earlier on Tuesday than 18Z. SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 300 PM Monday...Northwest winds of 10-15 knots and on occasion 15-20 knots will prevail across the area through the period. The persistence will be provided by a very deep and slow mid level trough at 500mb that trudges across the conus from the Mississippi Valley. Significant seas will be mostly 2-4 feet with the higher values across the outer waters with the offshore flow. LONG TERM /THURSDAY THROUGH SATURDAY/... As of 300 PM Monday...High pressure moving overhead the waters Thursday into Friday will create gusty north winds early Thursday before weakening to less than 10 kts and shifting slowly to NE Friday, and then E on Saturday. A secondary front approaching very late Saturday may cause winds to uptick again at the end of the period. The gusty north winds early will keep seas elevated at 3-4 ft the first half of Thursday, before falling back to 1-3 ft Fri and Sat. The increased winds late Saturday may cause seas to begin to rise again at that time.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until 2 PM EDT Tuesday for AMZ250-252-254- 256. && $$ SYNOPSIS...JDW NEAR TERM...CRM SHORT TERM...SHK LONG TERM...JDW AVIATION...MAC

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