542 FXUS62 KILM 070421 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1221 AM EDT Sun Nov 7 2021 .SYNOPSIS... Strong low pressure off the Southeast coast will bring significant coastal flooding and beach erosion, along with periods of rain and breezy winds to the area tonight through Sunday. Calmer weather conditions are expected to develop Monday through Thursday as high pressure builds in. The next rain chance will develop Friday as the next front approaches. && .UPDATE... WWA Section updated. Previous Update... A decent area of rainfall has finally made it to the coast and the latest near term/high resolution guidance shows this may be the best activity for this event. No significant changes with the late evening update. && .NEAR TERM /THROUGH MONDAY/... Though impressive on satellite the area of low pressure just east of Jacksonville, Florida has failed to produce much rainfall locally. This may change overnight into early Sunday as the low begins to move to the northeast but most of the moisture should remain to our east. Similarly there will be a significant west-east gradient in qpf potential. The main impacts from this storm now appear to be the nasty marine conditions and coastal flooding, outlined below. A small diurnal curve heading into tonight with gusty N winds keeping the atmosphere mixed beneath the shallow inversion. This same inversion will be keeping the 50-60kt winds at 925 mph mixing down luckily, though there is still some concern that should rainfall rates get sufficiently high this stability could be overcome. The wind and rain abate Sunday, the speed at which is still uncertain due to the considerable spread in model guidance. Of more certainty is that it will be another cool and breezy day. Faster model solutions may even favor decreasing clouds from west to east. This will allow for a more seasonably cool Sunday night. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... A low amplitude upper ridge centered over the Gulf of Mexico will build toward the Carolinas Monday and Tuesday as the offshore surface low and upper trough move away from the area. Breezy north winds still gusting up to 25 mph along the coast Monday will diminish Tuesday. It's essentially just a temperature forecast both days, and my forecast highs and lows are midway between the GFS (small diurnal range) and ECMWF (large diurnal range). The 12z operational GFS might first appear to be a slow outlier with the offshore low versus the faster/farther east Canadian and ECMWF, but the GFS is consistent with its own ensembles and therefore isn't being discounted. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... The next shortwave trough will eject east of the Rockies early Wednesday, moving into the Plains and western Great Lakes by Thursday and Friday. The GFS is 12-18 hours faster than the ECMWF with the eastward movement of the associated surface cold front, and appears too fast relative to its own ensembles as well. The Canadian is even slower than the ECMWF and suggests the front won't arrive Saturday. This spread leads to low confidence with regard to temperatures, clouds, and rainfall potential Friday and Saturday. Low rain chances (20-30 percent) first appear in the forecast Thursday night, increasing to 40-50 percent Friday, then diminishing Friday night into Saturday due to the aforementioned uncertainty regarding timing of the upper level system. Above normal temperatures in the 70s Wednesday through Friday will probably begin to cool Saturday assuming the front has arrived by then. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... Sites initializing with MVFR this evening and this may be the lowest categories get. Moderate to even heavy rain axis may very well stay offshore overnight seemingly maintaining the current state conditions. Conditions still expected to improve later Sunday. Extended Outlook...VFR is expected Sun evening through Wed with gusty but slowly abating N-NE winds continuing into Mon. && .MARINE... Through Sunday night...Long duration Gale continues with 35-40kt winds and 12ft seas at 41013 but also 6+ ft waves buffeting Masonboro Island buoy 41110, all being driven by both low pressure strengthening east of JAX but also a long NE fetch into the Carolinas around New England high pressure. Monday through Thursday...Strong low pressure several hundred miles southeast of Cape Fear on Monday morning will shift east and away from the Carolinas Monday night into Tuesday with decreasing wind speeds and improving seas expected. Small Craft Advisory conditions should continue through Monday due to winds and seas, and could continue into Tuesday night depending on how quickly a large easterly swell produced by the offshore low remains a factor. Improving weather should be here by Wednesday into Thursday with high pressure. && .TIDES/COASTAL FLOODING... Some impressive tides this morning in the strong NNE fetch around not only the storm off of JAX but also hundreds of miles of E winds into the southeast coast around a SW to NE elongated high over New England States. Beaches will reach advisory levels with this evening's tide, the lower of the two but the event will peak with tomorrow morning's tide. The eastward elongation of the JAX low into its own warm advection zone will increase the length and better align wave energy locally as should the strengthening of the low. Beaches should reach moderate/warming level coastal flooding. Such tides paired with the High Surf-worthy 6 ft breakers will lead to more serious flooding of low lying areas as well as cause beach erosion that may even begin to encroach upon dunes. In fact many places are expected to see tide levels not experienced outside of hurricanes. Confidence was high enough at this point to skip the watch phase and go straight to CF warning. Several more cycles of advisory-level flooding are expected after Sunday morning as the astronomical tides wane, but the bigger and more uncertain factor will be the speed with which the low finally decides to depart to the NE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...Coastal Flood Warning from 7 AM this morning to 1 PM EST this afternoon for SCZ054-056. High Surf Advisory until 7 PM EST this evening for SCZ054-056. NC...Coastal Flood Warning from 7 AM this morning to 1 PM EST this afternoon for NCZ106-108-110. High Surf Advisory until 6 AM EST Monday for NCZ106-108. Coastal Flood Advisory until 1 AM EST early this morning for NCZ107. MARINE...Gale Warning until 7 PM EST this evening for AMZ250-252-254- 256. && $$ SYNOPSIS...TRA UPDATE...DCH/SHK NEAR TERM...MBB SHORT TERM...TRA LONG TERM...TRA AVIATION...SHK MARINE...TRA/MBB TIDES/COASTAL FLOODING...MBB