Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 240104

Area Forecast Discussion
National Weather Service Wilmington NC
904 PM EDT Wed May 23 2018

A weak cold front approaching from the north will produce a
continued low chance for showers and thunderstorms late this
evening and overnight. The front across or just south of the
local area will dissipate during Friday. Low pressure
developing across the Gulf of Mexico will bring tropical
moisture northward and help fuel a higher probability of showers
and thunderstorms with heavy rain across the eastern Carolinas
Sunday and into early next week.


As of 845 PM Wednesday...The diurnally induced convection across
the FA is waning fast at the moment and is nearly gone. Have
lowered POPs to chance or slight chance for the remainder of
this evening as a result. However, HRRR model runs indicate
that as the sfc cold front drops further south and across the FA
toward daybreak, showers and or tstorms could re-develop given
a better convergence zone for initiation. As a result, have
kept the 20-30 POPs going thruout the night. Some tweaks to
overnight mins and Hrly temps and dewpts based on trends with no
categorical changes.

As of 300 PM Wednesday...A mid-level disturbance along the
Savannah River surrounded by very light steering flow should
move very little over the next 24 hours. Surface high pressure
moving across the Great Lakes will nudge a surface cold front
southward across North Carolina tonight, stalling out across
eastern South Carolina on Thursday. This should be the focus
for another day of showers and thunderstorms.

Today`s thunderstorm activity is developing along multiple
east-west oriented convergence boundaries where the airmass is
uncapped with CAPE of 1500-2500 J/kg. Convective organization
has remained minimal due to very weak wind shear: bulk shear
across the 0-6 km layer is only 10-20 kt. SPC`s marginal severe
weather threat across northeastern NC and southeastern VA is
keyed to the stronger shear and potential for more significant
storm cell organization that exists there.

Convective activity should diminish this evening, however
most recent runs of the synoptic and rapid update models show
convection lingering through the night along the south end of
the higher shear zone across North Carolina, particularly as the
cold front eases its way south overnight and increases low-
level convergence. A relative minimum in convection should occur
Thursday morning, with showers and storms reblossoming Thursday
afternoon mainly across South Carolina near the stalled front
and pooled low-level moisture. Forecast PoPs are as high as 70
percent in the Florence vicinity Thursday afternoon.

Lows tonight should range from 68-71. Highs Thursday are
forecast to reach 80 on the beaches to around 84 inland.


As of 3 PM Wednesday...Weak upper low across GA Thursday night
will drift northward and weaken further across the far western
Carolinas during Friday. In addition, the H5 ridge situated off
the coast will help direct moisture plume back into the
Carolinas and precipitable water will increase during the day in
response. Expect the best convective coverage to be across the
SC zones initially during Friday, then in the LBT zone group
later in the day. During Friday the residual foot print of the
old front will drift northward and finally become absorbed in
the broader scale flow and awash in the sea breeze circulation.
Favor a blend of MAV/MET numbers through the period which
suggests near climatology high temperatures Friday and warmer
than normal low temperatures each night.


As of 3 PM Wednesday...A return to a very wet period appears to
be in order for the extended time frame. A ridge of high
pressure will weaken and the trough will open up across the
eastern half of the United States. The models continue to show a
low developing over the Gulf either as a subtropical or
tropical system. For our area this means we should expect to see
increased moisture and the chance of heavy rain. The models
continue to show a surface low developing over the Gulf of
Mexico, the 12Z ECMWF shows the low moving northward to
Louisiana and slowing off the coast on Tuesday. The GFS is near
the Florida peninsula and the Canadian is in middle. With the
recent rains flood watches may be required Sunday into early
next week.

With cloud cover and rain chances high temperatures are expected
to remain in the middle 80s and lows should be range from 68 to
73 through the period.


As of 23Z...Convection approaching KFLO and KLBT has been
weakening and will continue until dissipating after sunset. Weak
frontal boundary will drop south overnight and result in a wind
shift early Thursday. Scattered convection is expected to
develop early Thursday afternoon along and south of the front.

Extended Outlook...Brief/local IFR visibility is possible in
thunderstorms Thursday afternoon. Tropical moisture returning to
the area Sunday and Monday could bring more widespread
thunderstorms with periods of IFR ceilings/visibility possible.


As of 845 PM Wednesday...Winds ahead of sfc cold front dropping
southward, will drop to 5 to 10 kt with the sfc pg ahead of it
becoming quite relaxed. By daybreak, the cold front`s position
will be near Cape Fear. This front will continue to push
southward and by midday will likely stall just out of the ILM
waters. Have continued the brief veering trend with winds until
it`s final direction of NE-ENE is established. Could see
isolated convection along and ahead of the cold front dropping
southward during this overnight period. Significant seas will
run 2 to 3 ft, with only a few 4 footers possible from Cape Fear
northward. The 8 to 9 second period SE Ground swell will
continue to dominate the overall seas with the higher producing
wave energy via spectral density plots from NDBC.

As of 300 PM Wednesday...High pressure pushing east across the
Great Lakes will ease a cold front southward through North
Carolina tonight. The front should reach the Cape Fear area
shortly after sunrise Thursday, with the boundary slipping south
along the Grand Strand between 8-11 AM. Southwesterly winds
ahead of the front should turn northeasterly behind the front,
but with no significant increase in wind speed expected.
Scattered showers and thunderstorms should end early this
evening south of Cape Fear but may continue overnight north of
Cape Fear. Showers/storms should develop again Thursday
afternoon, mainly south of Cape Fear. Seas currently around 3
feet should diminish by about a foot with lighter wind speeds on

As of 3 PM Wednesday...Onshore flow around 10 knots expected
Thursday night with seas less than 3 ft. As high pressure off
the Southeast U.S. becomes better established the flow will veer
to a southerly wind by Friday night. Chance of showers and
thunderstorms across the waters, more-so during Friday and
Friday night. Seas 3 ft or less expected Friday and Friday

As of 300 PM Wednesday...As high pressure off the coast shifts
eastward and a trough of low pressure exists over the east half
of the United States, the winds will be from the south-
southeast to south-southwest at 10 to 15 knots. This extended
period of fetch will see the seas rising from around 2 to 3 feet
on Saturday to 4 to 6 feet by late in the day on Monday, when a
small craft advisory may be needed.




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