Area Forecast Discussion
Issued by NWS Newport/Morehead, NC
Issued by NWS Newport/Morehead, NC
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634 FXUS62 KMHX 250222 AFDMHX Area Forecast Discussion National Weather Service Newport/Morehead City NC 1022 PM EDT Tue Sep 24 2024 .SYNOPSIS... High pressure will remain anchored to the north through midweek as a warm front approaches eastern North Carolina from the west and stalls. TC Helene will pass through the Southeast US and bring a period of heavy rain and gusty winds to the area. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... As of 2200 Tuesday...The bulk of the forecast remains unchanged as previous iterations are tracking very well. The warm front, currently located near the HWY70 corridor, will continue to meander over the FA through the overnight. Have added mention of patchy fog in the early morning hours to highlight possibility of lower VIS in the morning hours. Best chance will be inland areas where winds are expected to be the weakest, but increased moisture convergence near the lingering boundary could lead to fog development along the front closer to the coast. Have incorporated latest runs of HiRes guidance into the PoP forecast to highlight the SChc of showers popping up along the boundary in the early morning hours as shortwave works overhead and front gets stretched Nward as its parent Low begins lifting N of the Great Lakes. Previous Disco...As of 345 PM Tue...Latest analysis shows mid- level ridge cresting over eastern NC this afternoon as a deep trough with multiple embedded shortwaves digs into the MS River Valley. The ridge is forecast to drift further offshore through the short term but still remain a dominant feature over the region as the aforementioned trough digs further into the southeastern CONUS and eventually cuts off. At the surface, a warm front currently west of Highway 70, abutting high pressure to our north. Any shower activity will fall apart after sunset, giving way to partly to mostly cloudy skies as the moist airmass expands over the entire FA. Like last night, some spotty showers are possible across the coastal plain as weak shortwave energy lifts across the Carolinas. Clouds keep temperatures mild, in the upper 60s to low 70s. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... As of 345 PM Tue...Warm front will gradually lift northward into Virginia tomorrow. Upper ridge will remain offshore but will act to shunt passing shortwave energy to the west, keeping the region sheltered from more robust precipitation. CAMs do hint at a recurrence of some spotty showers and thunderstorms, and although confidence is low opted to put in a broad slight chance PoP to account for this risk. Any activity will be spotty, but with PWATs of 1.5-1.75" and CAPEs around 1000 J/kg there is a risk of heavier rainfall in stronger activity. Highs rise with an increase in low-level thicknesses, hitting the mid 80s inland and around 80 along the coast. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... As of 200 AM Tuesday... - Above normal temperatures mid-week - Watching the tropics late Thursday into Friday Thursday-Friday: The main item of interest during this time will be the track of Potential Tropical Cyclone #9. 00z deterministic and ensemble guidance continue to be fairly well clustered on an inland track through the Southeast U.S. after making landfall along the Gulf Coast of Florida. The most notable change is a slight eastward shift noted in the ensemble mean track. Based on the latest available guidance, it appears that we`re getting some clarity on what the impact to ENC may be. If the current forecast track from the NHC holds, ENC will remain well east of the center of circulation. However, strong moisture advection east of the center should allow a plume of tropical moisture to quickly overspread the coastal Carolinas Thursday night into Friday. At the same time, a broadly diffluent flow aloft plus increasing WAA should support a period of strong forcing, leading to a quick period of moderate to heavy rain and scattered thunderstorms. While quick-hitting, guidance has been showing a consistent signal for heavy rain focused on Thursday night and Friday for at least a portion of ENC. Instability is forecast to be low, but strong shear/helicity to the east of the tropical system will need to be watched for a conditional tornado risk. Additionally, a strengthening pressure gradient, modest mixing, and a strong southerly LLJ should allow a period of gusty winds to accompany the rain and thunderstorms on Friday. This will especially be the case along the coast. With the subtle eastward shift in the guidance, winds and precip have increased some compared to the previous forecast. While this currently appears to be a quick- hitting scenario for ENC, it has been very wet of late, so it may not take as much rain to cause some hydro issues. What`s outlined above appears to be the most likely scenario based on the latest NHC track and model guidance. Stay tuned, though, as any shift west, or east, would lower or increase the impacts, respectively. Saturday-Tuesday: In the wake of the tropical system, a backdoor cold front is forecast to move through ENC on Saturday, and may be accompanied by a few showers. Temperatures will take a step down as well. By early next week, a surface low may develop off the coast of ENC as the Mid-South cutoff low finally opens up and moves east towards the Southeast U.S. coast. This is several days out, but is worth noting as it could bring another round of gusty winds and heavy rainfall. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... SHORT TERM /through 18z Wed/... As of 1900 Tuesday...Primarily VFR flight cats in place with some lingering MVFR CIGs centered to the NW. Warm front currently along a NW to SE line near EWN, will continue to meander over the FA through the period. Risk of showers will be low (10% or less) through the first part of tonight but chance of iso to widely scattered showers focused along the warm front increase in the early morning hours lasting through the evening. Guidance continues to show decreasing CIGs as stratus impacts area terminals. Have included mention of BR this TAF cycle as moisture convergence along the front may be enough to lead to some patchy fog in the early morning hours. Best chance for lowest CIGs over inland terminals with IFR possible. Conditions begin improving with sunrise, VFR returning late. LONG TERM /Wed through Sat/... As of 200 AM Tuesday... - Watching the tropics late Thursday-Friday SCT SHRA and TSRA may be ongoing Wednesday morning, but a general lull in TSRA activity is expected for most of Wednesday and potentially even into Thursday. Thursday night into Friday, a tropical system is forecast to pass well west of eastern NC, but still be close enough to produce a period of gusty winds, RA, TSRA, and sub-VFR conditions. Sub-VFR conditions and SHRA may linger into Saturday. && .MARINE... SHORT TERM /Through Wednesday/... As of 350 PM Tue...Seas continue to outperform guidance north of Cape Hatteras, still sitting at 7-8 feet as swell from a distant offshore low continues to roil the Atlantic. South of Hatteras, seas remain at 2-4 feet. Northeast to easterly winds remain at around 10 kt ahead of an approaching warm front. The warm front is expected to lift north through tomorrow as winds veer from northeasterly to southeasterly through tonight and into Wednesday morning, still holding at around 10 kt. The low responsible for the northeasterly swell will continue to drift further eastward, and waves will finally fall below 6 feet for waters within 10 nm. However, seas will likely be at or exceed 6 feet for outer zones and a SCA remains in effect for the short term. LONG TERM /Wed through Sat/... As of 200 AM Tuesday... - Elevated seas mid-week - Watching the tropics late-week Elevated seas continue across the coastal waters mid-week, especially north of Cape Hatteras, thanks to a persistent northeasterly long-period swell. Winds will remain relatively light during this period, though, and range from 5-15kt. Late Thursday into Friday, we`ll be closely monitoring a potential tropical system that is forecast to move inland across the Southeast U.S. The latest guidance keeps this system well west of ENC. However, a strong gradient east of the system should support a period of moderately impactful winds and seas. With this forecast update, we`ve increased winds Thursday night into Friday, and are now showing a period of 15- 25kt south to southeast winds. Recent guidance suggests some 30-35kt wind gust potential, but this is highly dependent on the track of the tropical system, so stay tuned. For now the key message is to plan ahead for gusty winds and building seas, with the impacts focused on Friday. && .TIDES/COASTAL FLOODING... As of 400 PM Tuesday... The coastal flood threat continues for all of coastal North Carolina into Wednesday as tide levels remain elevated. This includes the added Neuse, Bay, Pamlico, and Pungo Rivers, where waters in Belhaven have only recently receded. Water levels at high tide tomorrow will be slightly lower than yesterday, but could still result in up to a foot of inundation above ground level. Along and north of Ocracoke, persistent northeasterly swell from a distant low offshore will continue to bring minor overwash concerns with maximum inundation around 1-2 feet. Looking ahead, we`ll continue to closely monitor the track of TC Helene as distant coastal impacts could be felt across a portion of ENC thanks to increasing southerly onshore winds. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...Coastal Flood Advisory until 5 PM EDT Wednesday for NCZ080-094- 194>196-199-203>205. Beach Hazards Statement through Wednesday evening for NCZ203- 205. MARINE...Small Craft Advisory until 2 PM EDT Saturday for AMZ150-152- 154. && $$ SYNOPSIS...MHX NEAR TERM...MS/CEB SHORT TERM...MS LONG TERM...RM/RCF AVIATION...RM/CEB/RCF MARINE...RM/MS/RCF TIDES/COASTAL FLOODING...MHX