Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 240204

Area Forecast Discussion
National Weather Service Wilmington NC
1004 PM EDT Tue May 23 2017

Waves of low pressure will continue to move along stalled cold
front producing a good chance of showers and thunderstorms
through mid week. Another cold front trailing from a deep low
pressure system over the Ohio Valley on Thursday will cross the
area, bringing the final round of showers to the area. High
pressure will build in late Thursday into Friday maintaining
quieter weather for much of the weekend. Low pressure may affect
the area early next week producing more unsettled weather.


As of 1000 PM Tuesday...The initial wave of heavy rain and
thunderstorms this afternoon apparently took more out of the
atmosphere than I realized. Despite model analysis still showing
elevated CAPE on the order of 500 J/kg across the area, showers
have become quite anemic looking on radar. Lighting is
currently confined to a line of convection 30-50 miles offshore
where there is surface-based CAPE over 1500 J/kg.

The synoptic quasi-stationary front current extends across the
Albemarle Sound southwestward to near Greenville NC, Southern
Pines, and on westward toward Charlotte. Deep moisture over the
area should thin out aloft overnight as a dry slot extending
down as low as 5000 feet AGL advects in from the west. This dry
air has already cleared precipitation out of Georgia and South
Carolina south and west of Columbia and Augusta.

Two final curved bands of showers should sweep northeastward
across the eastern Carolinas overnight. Heavy rainfall potential
appears to have waned inland, however along the coast there is
still some potential for heavy rainfall given the possibility of
training along the South Carolina beaches up into Cape Fear
between 11 PM and 2 AM.

Changes to the forecast with this late evening update mainly
centered on adjusting forecast PoPs, QPF, and weather based on
extrapolation of latest radar trends.

Note: A storm survey will be performed Wednesday in the Parkton
community of northern Robeson County where a shower produced
wind damage between 345 and 400 PM this afternoon. The observed
damage near Parkton connects up with a long trail of damage
reports that extends eastward through Cumberland and Sampson
counties that appears to have been tornadic. We`ll have more
details after the survey tomorrow.


As of 300 PM Tuesday...Deep moisture associated with cold front now
progged to get shunted offshore more quickly than previously thought
early Wednesday night and this period should mark the end of
appreciable rainfall. Light shower activity will persist but in a
more spotty fashion thereafter as increasingly strong PVA and height
falls impinge from the west. In fact, the coverage and intensity
should pick up midday Thursday as the fairly impressive 32 s-1 vort
and -21C trough axis swings through at 500mb. In fact this energy
swings through so quickly that the low level CAA shuts off Thursday
night but not before dropping enough to support some lows in the
upper 50s with low 60s along beaches.


As of 300 PM Tuesday...Plenty of dry air will move in with deep
westerly flow on the back end of exiting low pressure system on
Fri. Pcp water values drop down to .75 inches or below early
Fri but do creep back up over an inch by late Friday. Overall
expect a sunny dry day on Friday with temps reaching into the
mid 80s.

High pressure ridge to the south will reach up into the
Carolinas maintaining pleasant weather through much of the
weekend. A shortwave rides across the top of the ridge over the
weekend mainly remaining north of the forecast area. This could
produce some clouds or a spotty shower late Sat into Sat night,
mainly over NC. The GFS builds the ridge a little farther north
and therefore holds any weather farther to the north with a deep
warm southerly flow and sunnier weather overall all weekend. A
deeper mid to upper trough digs down late in the weekend and
could produce an increase of clouds and showers Sun through Tues
timeframe. Will have to see how the models evolve. For now,
will keep chc of shwrs north of area through Sat night but will
include Pops for Sun through Tues.

The building ridge and westerly downslope flow through the mid
levels will produce above normal temps through much of the
period with temps reaching above 90 in spots especially over
the weekend.


As of 00Z Tuesday...Showers and embedded thunderstorms this
evening should move east and offshore after 05-07Z tonight as a
surge of drier air in the mid levels moves overhead. Until then,
convective showers and possibly thunderstorms could produce
MVFR visibilities at times. Plenty of low level moisture should
result in ceilings lowering to 500-1000 feet overnight. The
best potential for these IFR ceilings will be inland affecting
the FLO and LBT airports, with the least potential at MYR and
CRE. Showers and embedded thunderstorms should return after
13-16Z Wednesday as deeper moisture builds back overhead from
the southwest.

Extended Outlook...Reduced flight categories will be possible
in periodic showers and thunderstorms into Thursday.


As of 1000 PM Tuesday...Small craft advisory conditions should
still develop shortly as a wave of low pressure moves along a
stalled front inland. Waves of showers and thunderstorms should
continue through 3-4 AM before drier air building overhead from
the west begins to erode the rain threat.

As of 300 PM Tuesday...Solid small craft advisory conditions
Wednesday night in not only a moderately pinched gradient but also
an environment characterized by increased wind fields aloft leading
to vertical momentum transfer. So now peak wind gusts may attain
35kt but at this time they do not appear to be near frequent enough
to warrant Gale Warning. Frontal passage comes early Thursday
leading to a veering to the west and a gradual decrease in sustained
wind speeds. The upper trough meanwhile may persist the gustiness
factor into the early afternoon. Winds may tick up a category in
speed in the CAA Thursday night, likely continuing the Advisory.

As of 300 PM Tuesday...A stronger off shore westerly flow on
Friday will diminish and back around to the W-SW through the day
as low pressure system exits farther off to the east and high
pressure builds up from the south. Seas of 3 to 5 ft will
diminish to 2 to 4 ft through Friday and down below 3 ft by Fri
night in weakening offshore flow.

High pressure south of the area waters will shift east through
the weekend into early next week producing a persistent SW
return flow. Initially winds will only be 10 kts or so but low
pressure moving by to the north Sat night into Sun and an
approaching cold front late in the weekend into early next week
may produce an increase in SW winds. Seas less than 3 ft
Saturday in lighter winds will rise up to 3 to 5 ft in
increasing SW winds Sat night into Sun.


SC...Flash Flood Watch through Wednesday evening for SCZ017-023-024-
     Beach Hazards Statement through Wednesday evening for SCZ054-
NC...Flash Flood Watch through Wednesday evening for NCZ087-096-099-
     Beach Hazards Statement through Wednesday evening for NCZ106-
MARINE...Small Craft Advisory until 8 AM EDT Thursday for AMZ250-252-



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