Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 180748 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 248 AM EST Wed Jan 18 2017 .SYNOPSIS... A cold front will drop south through the region today. Weak high pressure will follow on Thursday. Low pressure will move up from the Gulf Coast and drag a cold front across the area on Friday. High pressure will build in on Saturday before another system brings unsettled weather for late Sunday into Monday. && .NEAR TERM /THROUGH TONIGHT/... As of 245 AM Wednesday...The bulk of the mid-level shortwave energy will swing across the central Appalachians and VA today, before heading out to sea. The southern most spoke of this energy will skirt the northern reaches of the forecast area. 07z Radar shows some light returns showing up along the NC and TN line and then stretching across the VA/NC border. The high resolution model, HRRR, shows some light showers skirting areas along and N of a BBP to ILM line after 15z. These showers will be occurring just ahead of a cold front which should slip S of the area this afternoon, shifting westerly winds to the N. The risk of showers will come to an end prior to dusk. In fact, mostly cloudy skies will begin to clear almost immediately behind the front this afternoon. Given the magnitude of mid-level dry air and with a deep westerly flow in place, it seems reasonable to keep the risk of measurable rainfall low and confined to the northern third or so of the CWA. Where rain does measure, it will be on the order of just a few hundreths, maximum. What most people will notice about today is that when they head out early this morning, it is just too warm for this time of year. We are above the normal high by several degrees already this morning. Consequently, today`s highs will be well above normal, lower to mid 70s. You will also likely notice the gusty winds as 35-45 kt of wind, riding 2-3 kft above the surface, partially mix down. Tonight, skies will clear and high pressure will build toward the area from the W. Winds will gradually become very light which will increase the effects of radiational cooling. Lows will be in the lower to mid 40s with some upper 40s to near 50 along portions of the immediate coast and South Santee River area. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 245 AM Wednesday...High pressure will be in place Thu, moving offshore Thu night. Clouds will begin to increase during Thu afternoon, but it will remain dry with above normal temps, lower to mid 60s. A storm system will be moving across the Midwest with its complex frontal system trailing south across the Tennessee Valley and south to the eastern Gulf Coast Friday morning. Moisture advection into the Carolinas will peak overnight Thu into the first portion of Friday and this is when we will advertise generally likely pops. The mositure return looks a little weaker and briefer as compared to 24 hours ago and this is partially due to weaker jetting. At this time, rainfall amounts should fall between one tenth and one quarter of an inch. Shortwave energy pivoting across the FA may spawn an area of weak low pressure along the North Carolina coast Fri night as the front stalls in close proximity offshore. Will contine to show POPs trending down Fri afternoon and will keep any showers offshore Fri night. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 245 AM Wednesday...An unsettled weekend ahead with the possibility of severe weather highlights the extended forecast. Saturday starts off with a broad southwest flow aloft with weak high pressure at the surface. Weak shortwaves in this flow along with some isentropic lift keep pops in the forecast through the day Sunday when a more organized system approaches from the southwest. Guidance shows a deep vertically stacked cyclone developing in the Mississippi Valley moving east throuigh the Carolinas through the day Monday. A deep subtropical plume of moisture accompanies the cold front late Sunday into Monday morning with accompanying high shear and low cape values. Low level wind speeds reach close to 60 knots at 850mb so any convective cells could translate strong winds to the surface. As is usually the cast this time of year low level instability will be the issue. The mid level low slowly moves across the area Monday into early Tuesday and depending on timing and any heating available some instability showers could develop. Mid levels will be drying out however. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... As of 06Z...Satellite imagery shows partial clearing continuing across the region as warm front has lifted well north of the region. Cold front across eastern TN will move into extreme western NC this morning and continue to move eastward throughout the day. Main issue continues to be the increased low level jet at H8 ahead of this frontal boundary and the threat for low level wind shear of 25-35 knots at about 1500 feet AGL through this morning. Have kept low level wind shear in the forecast for Florence, Wilmington, and Lumberton. Another concern is sea fog developing off the coast, but as of now, it is expected to remain just offshore of the two Myrtle Beach airports. However, a slight shift in the wind direction could bring this fog onshore. It is hard to discern on satellite so will have to wait on surface reports for verification. Not much change from previous discussion regarding stronger westerly winds in advance of a cold front mixing down to the surface during the morning with wind gusts in the 18-25 knot range possible. Again cannot rule our some light showers from a mid-cloud deck near the front as it passes with best chance in the Wilmington area. Still will keep prob in the tafs for the other terminals with a tempo for KILM along with MVFR conditions in ceilings, VFR throughout across all other terminals. Extended Outlook...IFR ceilings are possible in low stratus Friday and Friday night as the next warm front and rainfall event develops. IFR ceilings could continue into Saturday morning as models indicate a cool air wedge possible. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 245 AM Wednesday...We will initialize with a Small Craft Should Exercise Caution headline for the northern waters and keep the headline through the day. The wind direction ahead of a cold front will be SW. The wind will shift to the N with passage of the front this afternoon and lastly across the far southern waters early this eve. Wind speeds today will be up to 20 kt N and 15 to 20 kt S. Seas will be up to 4 to 5 ft, otherwise 3 to 4 ft today. High pressure will build in from the W and NW tonight. The wind direction will veer slightly, from N to NNE/NE overnight. Wind speeds tonight will generally be 15 to 20 kt, but will show a downward trend toward morning. Seas will be up to 3 to 4 ft in the eve with some 5 ft seas across the outer northern waters. Seas will subside to 2 to 3 ft throughout overnight. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 245 AM Wednesday...High pressure Thu will move offshore Thu night. An area of low pressure and its associated frontal system will move across the area Fri. Weak low pressure may develop Fri night as mid-level shortwave energy pivots across a frontal boundary, in close proximity offshore. NE winds Thu will become E and then SE Thu night. The wind direction will further veer to SW during Fri and then W and NW overnight Fri. Wind speeds of 10 to 15 kt will be common through the period. Seas should not exceed 2 to 3 ft during the forecast period. LONG TERM /SATURDAY THROUGH SUNDAY/... As of 245 AM Wednesday...Weak high pressure will lead to benign conditions for Saturday and most of Sunday for that matter. Wind speeds will be mostly ten knots or less and the synoptic direction from the east/northeast. Speeds do pick up a little later Sunday via an approaching front and the direction veers to the southeast. Significant seas will be 2-3 feet. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...SHK NEAR TERM...RJD SHORT TERM...RJD LONG TERM...SHK AVIATION...RJD/MAC

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