Area Forecast Discussion
Issued by NWS Wilmington, NC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KILM 231454
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1055 AM EDT Mon Oct 23 2017

.SYNOPSIS...
A strong cold front will approach from the west today and slow,
finally moving completely offshore Tuesday afternoon. Showers
and thunderstorms are expected along and ahead of the front with
the possibility for a line of strong to severe thunderstorms
late day and tonight. In the wake of the front, dry and cool
air will filter in mid week as Canadian high pressure takes
hold. Showers in association with developing low pressure may
return to the area this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1040 AM Monday...No changes to the forecast or reasoning
behind it. HSLC severe weather still likely on track for the
overnight hours. In fact, CAPE may not even be as lacking as
previously thought at least according to latest WRF forecast
soundings. Will have to see how much we warm up today given the
extensive cloud cover in place, especially since temperatures will
be atypically slow to fall this evening as the event takes shape.
WRF is a tad slower and a bit stronger with wind fields in
comparison to other guidance and still very much indicative that a
wind/tornado threat should materialize.

As of 300 AM Monday...Weak low-level convergence off the SC coast
associated with a subtle surface trough is helping to generate
widely scattered light showers, which will stream northward through
the pre-dawn hours. Shower activity will increase from west to east
through the afternoon well ahead of a strong, negatively-tilted 500
mb trough, which will be lifting across the OH river valley today.
A 40-50 knot southerly low-level jet will traverse the CWA in
the late afternoon and early evening, and SPC has included
the CWA in a slight risk for severe thunderstorms. There will be
potential for damaging winds gusts as convection may strengthen
in the moist and marginally unstable air in place ahead of the
cold front. Wind fields will also become supportive of rotating
updrafts and provide the potential for a few tornadoes.

The front will enter the western CWA around 06Z Tuesday, and
should be approaching the coast by 12Z. Even outside of convection,
southerly winds will gust to 20-25 mph this afternoon as the
gradient tightens up ahead of the front.

Max temps, and therefore destabilization may be limited by
cloudiness generated by upstream convection early in the day, but
temps will still climb to the upper 70s to near 80. Lows Monday
night will range from around 60 inland to around 70 along the
coast.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 300 AM Monday...Deep low pressure will be located across
the Great Lakes Tue with a strong cold front draped S across the
Eastern Seaboard. This front is expected to exit the eastern
Carolinas later Tue morning through early afternoon. The punch
of dry air behind this negatively tilted system should cut off
any showers across the I-95 corridor by or just after first
light Tue. However, given the orientation of the system, it may
take considerably longer before the last of the showers and some
thunderstorms move completely offshore with the showers
persisting into the afternoon along the Cape Fear coast. The
strongest low level jet will have shifted well N of the area Tue
morning and we do not expect severe weather on Tue across the
eastern Carolinas.

We will see dewpoints drop in the wake of the front with dry air
being reinforced later Tue night into Wed as the wind direction
shifts from SW and W to NW. Dewpoints will drop 20 to 30 degrees,
bottoming out in the upper 30s to around 40 during the later
half of this forecast period.

Skies will be clearing on Tue, first across inland areas with
thick cloud cover hanging on longest along the coast, especially
the Cape Fear coast where it may take a good part of the
afternoon before skies begin to clear. Thereafter, we do expect
mainly clear skies throughout.

Highs on Tue will be in the mid and upper 70s with the cold
advection kicking in strongly by Wed, highs will only reach the
mid to perhaps upper 60s. Lows Tue night will be in the mid and
upper 40s inland and mainly lower to mid 50s at the coast with
40s throughout Wed night. At this time, it does not appear it
will get cold enough, especially given the warm soils, for any
patchy inland frost to develop with this cold snap.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 230 PM Sunday...Initial portion of the Long Term looks to
be dry as high pressure transits east across the eastern
Carolinas in the wake of a cold FROPA. Showers moving in
advance of the next cold front may impact the area as early as
Saturday, but model solutions are still quite divergent as far
as timing goes, with the ECMWF holding off on FROPA until after
the weekend and the GFS being earlier. So, will limit pops to
slight/low chance for this weekend until the picture becomes
clearer. It is possible that the weekend may also end up dry.
Temperatures will start off below normal for late October,
warming to more climatologically-correct levels by Friday.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
As of 18Z...Quite a bit of uncertainty with respect to the timing of
the precip and ceilings. Safe to say the ceilings and visibilities
will be highly variable, especially this evening and through the
overnight hours. Some good dynamics heading our way, with good
frontal lift and decent helicity this evening. Thunder is a good
possibility,but mainly inland as the models tend to weaken the
convection as it reaches the coast. The convection will likely end
at the inland terminals by 03-04Z, however precip could linger along
the coast until around 12Z

Extended Outlook... VFR Wednesday through Friday. Slight chance for
showers Saturday.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 500 AM Monday...Seas building a little quicker than
previously thought and so a Small Craft Advisory is in effect
beginning at 10 am. Latest buoy observations indicate southeast
winds 15 to 20 knots across the waters, and these will veer to
the south and increase through the day as the pressure gradient
tightens well ahead of an approaching cold front. Wind speeds
will increase to 20 to 25 kt with higher gusts and seas will
build to 5 to 8 ft. The worst of the conditions are expected
tonight and into the early morning hours of Tue.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 300 AM Monday...Small Craft Advisory conditions should be
waning on Tue with seas dropping below 6 ft across the outermost
waters, lastly across the northern waters during the afternoon.
Seas will be mainly 4 ft Tue night and 3 to 4 ft for the remainder
of the period. SW winds will be weakening across the waters Tue
as the strong low level jet shifts N and we expect wind speeds
of 15 to 20 kt Tue morning to diminish to 10 to 15 kt Tue
afternoon. The arrival of colder and drier air across the waters
should allow wind speeds to kick back up to 15 to 20 kt for
much of the remainder of this forecast period as the direction
veers to WNW and NW.

LONG TERM /THURSDAY THROUGH FRIDAY/...
As of 230 PM Sunday...High pressure transiting east across the
waters will lead to gradually improving boating conditions with
dry weather through the long term. Period starts out with NW
winds of 15 to 20 kts and 3 to 5 ft seas in the wake of the
previous days FROPA, but expect conditions to be become more
favorable as the high moves overhead, with winds of around 10
kts by Friday and seas of around 2 ft.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory from 10 AM this morning to 2 PM EDT
     Tuesday for AMZ250-252-254-256.

&&

$$

NEAR TERM...mbb/CRM
SHORT TERM...RJD
LONG TERM...REK
AVIATION...43


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.