Area Forecast Discussion
Issued by NWS Newport/Morehead, NC
Issued by NWS Newport/Morehead, NC
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085 FXUS62 KMHX 140806 AFDMHX Area Forecast Discussion National Weather Service Newport/Morehead City NC 406 AM EDT Sat Sep 14 2024 .SYNOPSIS... A surface trough off the coast of the Carolinas will weaken today as high pressure remains wedged across the mid-Atlantic and central Carolinas. Low pressure developing off the Southeast U.S. coastline impacts the area over the weekend and into early next week, before moving inland mid-week. Troughing will remain over the Eastern Seaboard through next week as well keeping unsettled conditions across ENC. && .NEAR TERM /TODAY/... As of 335 AM Sat...Mid-level Rex block remains in place over the eastern CONUS this morning as the remnants of Francine continue to swirl over the lower MS River Valley, while upper ridge continues to linger over the Great Lakes and southeastern Canada. Mid-level convergence axis draped over the Carolinas will eventually be shunted southward this evening by a shortwave trough currently diving out of the Gulf of Maine, and the upper ridge is forecast to expand southward ushering in subsidence and drier air. At the surface, weak coastal trough continues to linger and provide enough lift for sporadic shower activity along the coast while wedge of high pressure remains locked in place for yet another day. Although the trough will be weakening through the day, it will continue to be a focal point for shower and isolated thunderstorm activity especially for coastal locations south of Oregon Inlet. Coverage will be at its most abundant during the diurnal maximum. PWATs will not be as high as yesterday, and with weaker upper level support do not expect to replicate the same impressive rainfall totals. In general, totals should remain below an inch but a few isolated higher totals of an inch or two are possible along the immediate coast. Since this is where the heaviest rain fell yesterday, this may be enough to reintroduce some minor flooding issues in vulnerable locations. Cloud cover and brisk northeasterly flow (gusting to 25-30 mph at times) will keep temperatures once again slightly below average for mid-September, in the upper 70s to around 80. && .SHORT TERM /TONIGHT/... As of 340 AM Saturday...The mid-level ridge will continue to slowly expand southward, pushing convergence axis and deeper moisture further south as PWATs fall to 1-1.5" area-wide. Easterly onshore flow means a spotty shower threat is still not out of the question along the coast into Sunday morning, but coverage will be increasingly isolated. Surface wedge still doesn`t budge, keeping low-levels saturated and yet another night of low clouds, especially west of Highway 17. Temperatures linger on the warmer side once again, with lows in the upper 60s to low 70s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... As of 330 AM Sat...An unsettled weather pattern is forecast for the entire period as a rex block will remain over the Eastern Seaboard through Sunday and into early next week keeping a blocking ridge centered to the north and a stalled frontal boundary and associated developing low pressure system off the Southeast coast. On Monday and into Tuesday, low pressure will slowly track northwards potentially impacting ENC during this timeframe. Afterwards troughing will remain over the Eastern Seaboard into Friday keeping things unsettled across the area with daily chances for showers and thunderstorms. With steady onshore flow over the next several days temps will remain at or below avg through the period as well. Sunday into Tuesday... There has been some clarity in the forecast since the previous update though the trend has certainly not been our friend this go around as there is an increasing likelihood of low pressure impacting ENC Mon into Tue bringing a threat for several hazards to the area. Rex block remains in place into Tue as a ridge of high pressure remains centered to the north while troughing remains over the Southeastern CONUS. In addition to this, a mid level low is also forecast to get spun up across the Sargasso Sea Sun into Mon, eventually becoming absorbed into the troughing. This will combine with an incoming shortwave from the west to deepen the aforementioned troughing across the Southeast on Mon and Tue allowing the previously mentioned ridge to weaken slightly on Tue night. At the surface, high pressure ridging will continue to wedge down into the Carolinas while a stalled front remains well off the coast on Sun. The interaction between these two features will continue to keep the pressure gradient tight allowing for blustery E`rly winds Sun and into Mon. Surface low pressure does begin to develop on Sun and it is now looking increasingly likely that it will detach from the front and track N to NW Mon into Tue potentially impacting ENC as a sub-tropical or tropical low during this timeframe. EURO and its ensembles have come on board with the GFS and its ensembles bringing a low pressure system into the Carolinas Mon night into Tue morning before this low pushes further north into the Mid- Atlantic and weakens. While there has been increasing confidence in low development, there remains low confidence in the exact track and strength of the low as it approaches the region with both EURO and GFS ensembles having a broad envelope of solutions for the overall outcome of the system. As of this update the NHC has recently increased 3/7 day development chances to 20%/50% and any development that would occur looks to be fairly rapid so lead time on this systems development will be unusually low given the circumstances. Regardless of if this system is tropical or not, heavy rain, coastal impacts, strong winds, and dangerous marine conditions will still be possible through Tue (SEE COASTAL FLOOD AND HYDRO SECTIONS FOR MORE INFO) Temps will remain at or below avg through Tue as well. Wednesday through end of the week... Previously mentioned upper trough will remain over the Eastern Seaboard through the end of the week while at the surface whatever low develops early this week will have moved to the north and likely dissipated by Wed. Either way, daily chances for showers and thunderstorms will remain possible across ENC into the end of the week as troughing continues to remain a focus for shower and tstm activity. Will note however, winds will finally ease by Wed as the pressure gradient relaxes as a weakness in the ridge centered to our north briefly develops, though a second ridge of high pressure does begin to extend south into the area by Friday. Otherwise continued onshore flow will keep clouds around the region while temps remain at or below avg. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM /through 06z Sun/... As of 135 AM Sat...IFR already solidly locked in across PGV/ISO early this morning as coastal trough lingers and wedge of high pressure attempts to build back in from the north. Signal for IFR is slightly weaker for OAJ and flimsier still for EWN, and favored a more predominant MVFR forecast for these terminals in the overnight hours. Northeasterly winds increase quickly after sunrise, and any IFR will quickly give way to MVFR shortly after 14z, and then VFR prior to 18z as coastal trough decays and drier air filters in from the north. Some lingering shower and thunderstorm activity is possible mainly along and south of a line from EWN to OAJ, but coverage is too isolated to mention in TAFs for now. Gusty conditions prevail across all terminals with gusts to 20-25 kt likely especially across the inner coastal plain. LONG TERM /Sunday through Wednesday/... As of 330 AM Sat... No significant changes in the forecast outside of an increasing likelihood of an impactful low pressure system moving across the region on Mon and Tue. Daily chances for showers and thunderstorms across ENC will once again bring daily chances for sub-VFR conditions through the entire period with the highest threat to see sub-VFR conditions on Mon and Tue as the aforementioned low makes its way across the area. Winds will generally remain NE-E at 5-15 kts with gusts up near 20-25 kts through Monday before winds shift to a more SE`rly direction and become much lighter Tue into Wed as the aforementioned low moves to the north. && .MARINE... SHORT TERM /through Saturday/.. As of 345 AM Sat...Poor boating conditions remain in place through the short term as high pressure wedge and northeasterly wind regime refuse to relent. Area observations show winds of 10-20 kt, with the strongest winds across Raleigh and Onslow Bays which are gusting to 25-30 kt at times. Offshore, seas are hovering at around 5-7 feet. Weather pattern will change little through the day, and as such winds will remain at currently observed levels through the short term. The persistent fetch, however, will act to steadily build seas and by sunrise on Sunday wave weights are likely to reach between 7-10 feet, with the roughest waters focused from Cape Lookout northward. Seas may be a few feet higher along the Gulf Stream. Forecast winds have increased from the previous update. This necessitated adding all remaining inland waters to the suite of Small Crafts, extending through the weekend. All other existing headlines are in good shape and did not need any changes. LONG TERM /Sunday through Wednesday/... As of 345 AM Sat...No significant changes on this update as dangerous marine conditions will continue across our waters through at least Tue and possibly into Wed as a tight pressure gradient and eventually a low pressure system impact our waters. High pressure centered to our north will continue to interact with a stalled front to our south keeping the pressure gradient tight Sun into Mon. This will result in ongoing 15-25 kt E-NE`rly winds with 25-30 kt gusts to start the period with these winds persisting into Mon. Low pressure system develops Sun night and eventually tracks N to NW across our area Mon night into Tue. This low may gain some sub-tropical or tropical characteristics as this occurs, but regardless if this low becomes tropical or not, marine impacts will be the same. Wind gusts closer to 30-35 kts will be possible at times especially as the aforementioned low moves through the area, though confidence is too low to upgrade ongoing SCA`s just yet. High pressure eventually weakens Tue into Wed allowing this aforementioned low to push north away from our waters and allow the pressure gradient to relax resulting in winds easing down to 10-15 kts with gusts up near 20 kts at times coming from a SE- SW direction from Tue afternoon on into the end of the period. Seas will remain rather elevated through just about the entire period with areas north of Cape Lookout seeing 8-12 ft seas on Sun increasing to 11-15 ft seas by Mon. Further south across the more protected waters of Onslow Bay, 4-8 ft seas will build closer to 5-9 ft Sun night into Monday. These elevated seas will persist into Tue morning before rapidly lowering Tue afternoon and evening as the aforementioned low moves through the area and to the north allowing the pressure gradient and therefore winds to finally ease. Expecting seas to lower to 3-6 ft across Onslow Bay by Wed morning while further to the north seas will lower from 11-15 ft Tue morning down to 5-6 ft by Wed morning. Daily chances for showers and thunderstorms will remain possible through the period as troughing remains entrenched over the Southeast. && .HYDROLOGY... As of 800 PM Friday...Threat for flash flooding has diminished for the rest of this evening. Beyond today, there continues to be a solid signal for multiple rounds of heavy rainfall associated with the development of low pressure off the Southeast U.S. coastline. We`ll continue to monitor trends in guidance, as a renewed flooding risk may develop in the coming days. && .TIDES/COASTAL FLOODING... As of 440 PM Fri...Persistent moderate to gusty ENE winds will continue through the weekend and could result in very minor (nuisance, 1 ft agl or less) water level rises for areas adjacent to the western/southern Pamlico Sound, Neuse/Bay/Pamlico/Pungo Rvrs as well as the oceanside. Low pressure system is expected to develop off the SE coast this weekend and early next week. NHC has increased the probability of tropical development to 40%. Regardless of tropical development, this system is expected to bring coastal impacts. Though there is still some uncertainty with respect to timing and magnitude of those impacts, they will likely include: an elevated rip current risk for area beaches, minor coastal flooding, rough surf, beach erosion and localized ocean overwash. Coastal issues could also be exacerbated by the upcoming King Tide. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...Beach Hazards Statement through this evening for NCZ196- 203>205. MARINE...Small Craft Advisory until 8 AM EDT Tuesday for AMZ131-135>137- 230-231. Small Craft Advisory until 8 AM EDT Wednesday for AMZ150-152- 154. Small Craft Advisory until 6 AM EDT Wednesday for AMZ156-158. && $$ SYNOPSIS...MHX NEAR TERM...MS SHORT TERM...MS LONG TERM...RCF AVIATION...MS/RCF MARINE...MS/RCF HYDROLOGY...MHX TIDES/COASTAL FLOODING...MHX