Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 221406
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1006 AM EDT Tue May 22 2018

.SYNOPSIS...
Isolated to scattered showers and thunderstorms will become more
numerous Wednesday into Thursday as a cold front sags into the
area from the north before slowly dissipating Friday. The holiday
weekend looks unsettled as a tropical airmass brings the likelihood
for showers and thunderstorms and possibly more heavy rain, especially
Sunday into Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 10 AM Tuesday...models continue to show the lower
precipitable waters (<1.5") through the mid afternoon before
moistening. The 12 UTC HRRR is showing isolated convection
mainly west of a line from Lumberton to Andrews.

The high resolution models are showing the development of a
resultant sea breeze beginning late morning along the Grand
Strand and expanding across the entire coastal area by the
afternoon. The HRRR does not indicate any convective development
with this boundary.

---Previous Discussion---

Atlantic ridge has pushed far enough west to hold the tropical
feed of deep moisture just south and west of local forecast
area. Moisture profiles and sounding data show moisture limited
to near the surface and above 18k ft. Pcp water values were down
near 1.25 inches early this morning. This shallow moisture
should produce some fog and stratus through daybreak. Once
mixing occurs the fog and stratus will break up and dissipate
leaving some stratocu around and cirrus through the afternoon.
Have included isolated convection mainly along sea breeze
boundary today. Should be enough sunshine to push temps into the
mid 80s most places this aftn with light southerly to on shore
winds.

As the ridge slips back to the east later today through tonight,
expect a deeper moisture feed to set up once again as winds
veer around to a more SW direction. As the moisture increases
from the SW, there will be an increasing chc of a shower or
thunderstorm across northeast SC mainly later this afternoon.
Pcp water values increase up to 1.8 inches by late this evening
across the Pee Dee region. The tip of Cape Fear and up the NC
coast toward Hatteras will be the last to see this increase in
moisture with pcp water values only near 1.15 inches through
late this eve but reaching up near 1.75 inches by daybreak Wed.
As this moisture flow increases, mid to upper trough will dig
down from the north edging closer the area. Looks like the
shortwave will remain west of local forecast area overnight and
therefore expect best chc of showers over central and western
Carolinas, but expect an increase in shower activity to return
later today into early Wed. Also expect a nocturnal uptick in
showers over the adjacent coastal waters which could begin to
brush the coast overnight into early Wed. The cloud cover and
increasing moisture will keep overnight lows up around 70.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM Tuesday...Bermuda ridge will weaken across the
area Wed. Upper ridge building across central portions of the
North American continent will help to carve out a trough across
the northeastern United States and down along the east coast.
This should be enough to allow a surface cold front to sag
south and into if not through the area late Wed night and Thu
morning. High pressure to the north will then briefly nose into
the area later Thu and Thu night as the front begins to dissipate
in close proximity.

The result should be a period of unsettled weather. Current
thinking is deep moisture and a frontal boundary will help to
enhance the development of numerous showers and thunderstorms
Wed with seabreeze convergence also a focus for deep convection.
Rainfall rates should be high given precipitable water values
will be very near 2 inches and this may lead to at least some
pockets of minor flooding given the antecedent soil conditions
from recent heavy rainfall. Drier air will struggle to make
inroads into the area later Thu and Thu night and will show POPs
trending downward from N to S, especially later Thu and Thu night.

It will be humid through much of the period, but later Thu and
Thu night, we should see dewpoints slowly trend lower from N to
S. Highs will be near or slightly above normal for late May while
low temps remain mid and late June-like.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 PM Monday...A brief break in the pattern is forecast
to continue into early Fri as a mid-level trough digs into New
England driving a surface cold front through the area. This
front will dissipate on Fri. While scattered showers and storms
will remain possible Fri, it is possible that northern areas of
the FA will get a break from the convection and may see a
little lower humidity for about 24 hours.

As southerly flow returns to the area Friday and through the
weekend, shower and storm chances will ramp back up again for
the holiday weekend. Temperatures through the extended range
will remain in the lower to middle 80s by day and upper 60s to
lower 70s at night.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
As of 12Z...VFR at KILM and KCRE this morning, with MVFR at
KMYR/KLBT, and LIFR fog and low stratus at KFLO. Expect all
terminals to become VFR by 13Z. Afterward there is low
confidence of tempo MVFR cigs through 16Z. Otherwise confidence
of VFR is high today. The chance of convection is low by all
models, thus will not mention precipitation in TAFs. Winds will
be SW 5-10 kt becoming S with speeds around 15 kt at the coastal
terminals. MVFR/IFR with BR/stratus again possible overnight.
Confidence of occurrence is high, but timing low.

Extended Outlook...The potential for MVFR/tempo IFR will increase
late Wed/Thur as a cold front drops across the area and again
during the weekend as tropical moisture returns.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Tuesday...High pressure still in control over the
waters with very weak south to southwest winds less than 10
knots. Seas are running around 2 to 3 feet from a southeast
swell at 10.5 seconds. A slight increase in both winds and seas
will occur near shore in aftn sea breeze.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM Tuesday...Bermuda ridge will weaken across the
waters Wed. Upper ridge building across central portions of the
North American continent will help to carve out a trough across
the northeastern United States and down along the east coast.
This should be enough to allow a surface cold front to sag
south and through the coastal waters Thu morning. High pressure
to the north will then briefly nose into the area later Thu and
Thu night. SW winds Wed and Wed night will shift to NW early Thu
morning and then veer quickly to NE and then E during Thu,
remaining onshore Thu night. The strongest winds this period
will be around 15 kt Wed afternoon and eve. Seas of mainly 3 to
4 ft Wed will subside to 2 to 3 ft Thu.

LONG TERM /FRIDAY THROUGH SATURDAY/...
As of 300 PM Monday...The gradient will ease considerably as a
cold front wavers and then dissipates Fri. E-SE winds Fri will
turn to the S Sat. Winds look to be 15 kt or less with seas of 2
to 3 feet through the period.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.

&&

$$
SYNOPSIS...
NEAR TERM...RGZ
SHORT TERM...RJD
LONG TERM...JDW
AVIATION...MRR
MARINE...



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