FXUS62 KMHX 081514 AFDMHX Area Forecast Discussion National Weather Service Newport/Morehead City NC 1014 AM EST Fri Dec 8 2023 .SYNOPSIS... High pressure over the Southeast pushes offshore later today and gradually moves further into the Atlantic on Saturday. A strong cold front will cross the region late Sunday bringing strong southerly winds and increased chances of showers and thunderstorms. High pressure then builds back in behind the departing front on Monday bringing fair weather back to ENC next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... As of 1000 AM Fri...No significant changes to the previous forecast. Highs forecasted to be in the low 60s across the region as sunlight filters through the high clouds today. Previous discussion...As of 645 AM Fri...Surface trough has moved well into the Atlantic while high pressure ridging continues to extend N from the Georgia Coast into the Carolinas this morning. Winds remain light out of the SW across ENC this morning as well. Biggest challenge has been temperatures as high cirrus ended up keeping portions of the CWA slightly more insulated than expected resulting in widespread low temps ranging from the low 30s to the mid 40s. Otherwise the forecast remains on track today. Continue to expect cirrus to stream in from the west bringing little in the way of impacts with it outside of some partly cloudy skies. . && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/... As of 230 AM Fri... Upper level ridge remains over the Eastern Seaboard on Saturday, however at the surface ridging pushes further into the Atlantic and a weak coastal trough begins to develop by early Saturday morning. Not much in the way of impacts will be felt from this developing coastal through Friday night as any precip that does develop will likely remain well offshore, though thicker cloud cover is forecast to begin to develop especially along the coast and OBX by daybreak on Saturday. With weak southerly flow continuing lows tonight will be a bit warmer than this morning with much of the area seeing temps in the 40s and low 50s. && .LONG TERM /SATURDAY THROUGH THURSDAY/... As of 300 AM Friday... KEY MESSAGES 1) Cold front to bring heavy rain, strong winds, and possibly a few thunderstorms Sunday/Sunday night 2) Turning cold and dry next week FORECAST DETAILS The main focus in the long term period continues to be the strong cold front that is forecast to move through the length of the US East Coast Sunday/Sunday night. This front will move through the region as a potent shortwave lifts northeast across the Southeast US/Mid-Atlantic States. Of note, ensemble guidance have trended a bit stronger with this wave which, at minimum, could support stronger large-scale forcing. Prior to the arrival of that main shortwave, there will be a weaker lead wave that moves through on Saturday. Moisture will begin to get pulled back north into the area as that wave moves through and, in tandem with a developing coastal trough, may lead to a few showers skirting the coast between Surf City and Hatteras. The antecedant airmass is very dry, so it will take some time to sufficiently moisten the column to support precip, and for this reason, I've kept the chance of showers on the low side, and confined only to the above-mentioned coastal areas. By Saturday night, a tightening pressure gradient will lead to an increasing southerly flow, with an uptick in moisture advection into the coastal Carolinas. With increasing WAA, this may allow a chance of showers to work inland through the night. Moisture transport will markedly increase on Sunday as the above-mentioned potent s/w approaches from the west, and begins to take on more of a negative tilt. Moisture advection will be aided by an anomalously strong SSWerly 50-60kt LLJ straight off the Gulf of Mexico/Western Atlantic. Within this flow, an impressive plume of 1.50"+ PWATs will surge north through the eastern Carolinas. There will be multiple sources of lift, including strong WAA, a diffluent flow aloft, moderate to strong frontal forcing, and a pre-frontal convergent axis. The combination of moderate to strong lift and anomalous moisture continues to point towards a solid 1-2" of rain areawide. For the most part, guidance has remained consistent with rainfall amounts. However, there continues to be some differences in where the highest amounts will be, and I suspect this is largely driven by where convection factors in (ie. supporting higher rainfall rates). Where convection occurs, rainfall amounts of 2-3" will be possible. The convective potential remains a forecast and messaging challenge. Despite strong warm/moist advection, lapse rates aloft will be weak, and temps/dewpoints may only top out in the 60s. The southerly flow over the cooler near-shore waters may factor in as well. All-in-all, this points towards a high shear/low CAPE scenario, with instability being a significant limiting factor for a greater severe weather potential. That said, because of the strong winds aloft, even weak convection could help to mix down some of those impressive LLJ winds. The main thunderstorm hazard expected, then, will be wind gusts of 50+ mph. The greater severe threat should stay offshore. Lastly, the strong kinematics at play, and a strong pressure gradient along/ahead of the front, will support a period of strong winds Sunday afternoon into Sunday night. Probabilistic guidance is giving a 50-70% chance of exceeding 45 mph gusts along the coast, and a Wind Advisory will be needed if these probabilities remain high. Inland, it will be windy as well, but 45 mph probabilities are lower (30-50% chance). Inland, the best chance of seeing 45 mph winds may actually come just behind the front as mixing deepens just prior to the stronger winds aloft shifting away from the area. Gusty winds will continue into the day Monday, but will gradually subside by late Monday. A dry and colder airmass then moves back in for next week, with a broad area of high pressure overhead. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... SHORT TERM /through Friday night/... As of 645 AM Friday...High cirrus continues to stream in from the west this morning bringing little in the way of impacts with ceilings above 20 kft. Continue to expect VFR conditions through the day today with light S-SW'rly winds across the entire CWA. As we get into Friday evening high cirrus may finally begin to thicken and lower, but even then expecting VFR conditions tonight as well, as latest forecast keeps cigs above 10 kft across ENC into Saturday morning. LONG TERM /Saturday through Tuesday/... As of 300 AM Friday... The main impact period in the long term will be Sunday-Monday as a cold front moves through. The front will be accompanied by widespread sub-VFR conditions, with periods of IFR, or lower, conditions expected in low CIGs, SHRA, and possible TSRA. Strong south winds will gust as high as 25-35kt Sunday afternoon and Sunday night ahead of the front. Behind the front, gusty northerly winds will continue into Monday. && .MARINE... SHORT TERM /through Friday night/... As of 3 AM Friday... Surface trough offshore continues to push further into the Atlantic this morning while surface ridge of high pressure centered to the south slowly pushes off the coast. This has allowed the gradient to become slightly pinched from the coastal waters of Cape Hatteras south. As a result 15-20 kt winds with 25 kt gusts have been noted over these waters over the last few hours while seas generally remain at 3-5 ft with ocnl 6 ft seas noted. This should come to an end within the next hour or so as the trough pushes further offshore so not expecting to issue any headlines for these slightly elevated conditions. Elsewhere 10-15 kt WSW'rly winds are noted. Winds are forecast to become 10-15 kts across all waters and back to a SW'rly direction by this afternoon. These SW'rly winds will continue through Friday night. Seas will lower as the winds lower as well, down to 2-4 ft by this afternoon and remain at 2-4 ft through the rest of the period. LONG TERM /Saturday through Tuesday/... As of 300 AM Friday... KEY MESSAGES 1) Hazardous marine conditions expected Saturday night into Monday FORECAST DETAILS Looking ahead to the weekend, the best boating conditions will be on Saturday. Winds will be light (5-10kt), and seas will be 2-3 ft. Conditions begin to worsen Saturday night, becoming hazardous Sunday through Monday as a cold front moves through. Ahead of the front, strong southerly Gales will develop, with a few storm force gusts possible over the warmer Gulf Stream waters. Seas will build to 7-14 ft during this time, highest from Cape Hatteras south. Across the cooler waters, winds will be near, or just below, gale force. A Gale Watch was considered for the warmer central and southern waters, but in collaboration with surrounding NWS offices, it was decided to hold off for at least one more forecast cycle to help nail down the magnitude of winds, and where the greatest risk of Gales will be. At some point, marine headlines are likely to be issued for all waters (mix of SCA and Gales). Behind the front, gusty northwesterly winds of 20-30kt will continue into Monday morning before gradually laying down. Seas will take some time to lay down, but should fall to 4-6 ft by Monday night or Tuesday. Along the front, widespread showers and scattered thunderstorms are expected. With such strong winds aloft, any shower or thunderstorm will be capable of producing areas of enhanced winds. Over the warmer waters, the showers and thunderstorms will likely be what helps produce occasional storm- force gusts. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...None. && $$ SYNOPSIS...MHX NEAR TERM...RCF/RJ SHORT TERM...RCF LONG TERM...RM AVIATION...RM/RCF MARINE...RM/RCF