Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 201032
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
631 AM EDT Sun May 20 2018

.SYNOPSIS...
Scattered showers and thunderstorms can be expected much of
the upcoming week, as humid air of tropical origin remains
across the region. Rain chances will increase late Wednesday
into Thursday, as a cold front slowly crosses the coast. High
pressure to the north, may bring a brief drying trend Friday
and Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 414 AM Sunday...The tropical moisture connection
continues to stream up from the the south around the western
periphery of Atlantic ridge, but the ridge will begin to exert
itself pushing westward through today as shortwave and upper
level jet lifts off to the north. Initially a narrow plume will
remain aligned up from the Grand Strand area up into NC inland
from the coast this morning, but this will get nudged inland and
farther west through today. Therefore places closer to the I-95
corridor this morning will remain quiet, but should see a
better chc of shwrs/iso tstms this afternoon before much of the
area experiences a lull in pcp later this afternoon. Without any
mid to upper level support, showers should remain less intense
today, with plenty of clouds remaining. Pcp water plume much
narrower this morning aligned right along the SC/NC coast with
values up over 2 inches. Inland closer to I-95 corridor, the pcp
water values were near 1.5 inches this morning, but as ridge
nudges westward, so will the moisture and, although it
diminishes slightly tonight, it looks like it will remain over
the area. Overall expect scattered to numerous showers and
isolated thunderstorms, with greater chc along the coast through
this morning and overnight tonight and greater chc inland this
aftn. The steering flow will weaken this afternoon and therefore
any thunderstorms that develop will be slower to move and could
produce some ponding of water or flooding of low lying or flood
prone areas in heavier downpours. Breaks in the clouds this
morning inland will jumpstart temps and should see temps closer
to mid 80s for highs while closer to the coast should be closer
to 80. Tonight will run on the warm side once again up near 70.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 345 AM Sunday...Tropical plume reflected in model PWAT
still meandering in variable orientations across the area due
to Bermuda High landward intrusion Monday afternoon and evening.
Sensible weather impacts may not be vastly different however,
expect perhaps the potential for rain-loading or rain-rates, as
enough moisture will remain present in concert with May warmth,
to generate at least scattered showers and isolated TSTMS. A
rebound in column moisture Tuesday may make this the wettest
day of the 2. Similarities prevail in rain trends as we have
seen recently, ocean convection in the morning near the coast
and Cape Fear, with inland afternoon convection spawned from
diurnal warming across interior NE SC and SE NC. MLCAPE/MUCAPE
plots this period warrant TSTMS isolated in coverage both days.
Daytime highs will run close to climatology, but minimums are
apt to run well above normal due to cloud cover and elevated
moisture of tropical origin, hindering radiational cooling
significantly.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 300 PM Saturday...Guidance differs considerably in the
extended with how much rain may fall during the middle of the week,
leading to lowered confidence in this part of the forecast. The GFS
seems to be the wettest Wed-Thu, while the CMC/ECM are much
drier across the Carolinas. The synoptic setup is comparable
through each model, with the key difference being the timing and
duration of moisture return as model PWATs vary. The GFS may be
a bit too wet, but deserves at least some credence due to the
pattern remaining similar to the past week, and the moisture tap
from the tropics remaining in place. Will maintain CHC POP Wed-
Thu, with Tue likely being the driest of the 3, and Thursday
potentially the wettest thanks to a cold front which will drop
into the region and serve as a focus for convection. Regardless
of how many showers develop, there will be a good chance for
showers/iso tstms each day Wed-Thu with temps slightly above
climo for highs, and well above for lows.

Front will weaken and dissipate friday which should lead to lowered
POP chances as high pressure tries to build into the region for at
least one day. However, this drier air may again be short-lived. All
extended models suggest a low pressure of tropical origin will
develop near the Caribbean and move slowly in that region. This will
again send a plume of tropical moisture towards the Carolinas
bringing a return to unsettled and humid conditions with continued
slightly above normal temperatures.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
s of 12Z...Moisture is beginning to wane with only light showers on
radar at this time. Some heating later today may enhance the plume,
but certainly not the rainfall totals we had yesterday. Southerly
winds will continue today, gusty by late morning. Some fog/stratus
again possible tonight.

Extended Outlook... Possible break in the action on Mon, but rain
returning Tue and Wed. Finally an air mass change on Thu.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 414 AM Sunday...Southerly flow 10 to 15 kts will gust up
near 20 kts as local waters remain on the western periphery of
the Bermuda High through tonight. Seas will drop below 6 ft by
noon today as winds let up a bit and become slightly more S-SW
as Bermuda High nudges westward. Seas will be down to 3 to 5 ft
this afternoon, subsiding slowly into Monday.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 345 AM Sunday...NO SCA flags expected this period, but
marine conditions will not be smooth. Occasional 20 kt SW gusts
this period and generally 4 foot seas to prevail in 8 seconds
wave periods from the SE, co-mingled with moderate southerly
chop. Scattered showers and isolated TSTMS can be expected, and
radar updates are encouraged before heading out. Out side of
synoptic 20 kt gusts, and shower/TSTM wind gusts, expect SW
winds 12-17 kt most of the time.

LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 300 PM Saturday...Continued high pressure offshore will
drive S/SW winds of 10-15 kts across the waters Wed. Early on
Thu, a weak front will drop into the area turning winds to the
W/NW Thu morning, before this front dissipate leaving a weak
gradient and variable winds through the end of the period. Seas
of 3-4 ft will continue Wed thanks to a SE swell and SW wind
wave. However, as the winds ease and become variable Thursday at
the same time the swell begins to deamplify, wave heights will
drop to around 2 ft late.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until noon EDT today for
AMZ250-252-254-256.

&&

$$

SYNOPSIS...MJC
NEAR TERM...RGZ
SHORT TERM...MJC
LONG TERM...JDW
AVIATION...43



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