379 
FXUS62 KILM 070652
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
152 AM EST 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 /07Z SUNDAY THROUGH THURSDAY/...
MVFR with occasional IFR expected during the pre-dawn Sun hrs as
bands of pcpn move onshore and inland. The worst of the flight
restrictions will occur at the coastal terminals this morning
with gusty NNW-NNE winds compounding the issue at all terminals
through late aftn. After sunset, the constant gustiness in the
wind fields will abate but Northerly winds will remain active 
around 10 kt. The pcpn and clouds will exit the Carolinas from 
west to east today, with the inland terminals seeing dominate 
VFR from midday onward, whereas the coastal terminals may take 
until late aftn to observe dominate VFR conditions.

Extended Outlook...VFR is expected to dominate Sun evening 
through Wed with continued active NNW-NNE winds late Sun night,
with some gusts, up to 15-20 kt, occurring daylight 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.
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...DCH
MARINE...TRA/MBB
TIDES/COASTAL FLOODING...