Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 170531
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1231 AM EST Sun Dec 17 2017

.SYNOPSIS...
A cold front will move into the area and stall Monday and Monday
night. Low pressure from the Gulf coast states will push across
the area Wednesday through Thursday with a chance for substantial
rainfall. High pressure will follow Friday. Another cold front
may arrive on Saturday.

&&

.NEAR TERM /THROUGH TODAY/...
As of 915 PM Saturday...Cirrus discernible on IR satellite loops
is too thin for any impact on radiational cooling. Light winds
and a very dry atmospheric column are allowing excellent
radiational cooling to occur, and temperatures continue to
plunge through the 30s except right on the beaches where some
40s are still showing up. A few more downward revisions have
been made to overnight low temp forecasts based on 9 PM
observations, otherwise no significant changes have been made.
Discussion from 300 PM follows...

Southern stream upper low exiting northern Mexico along with
the belt of stronger winds from the northern rockies into the
Great Lakes and southern New England will maintain an area of
confluence across the Eastern United States. Other than some
thin high clouds the column in our area will remain mostly dry
as a result through tonight. As the upper low lifts across the
Central Plains late tonight and further dampens across the
Midwest during Sunday moisture (generally above H85) will begin
to increase across the Carolinas. Thus clear/mostly clear skies
will give way to increasing cloudiness, especially later in the
near term period. After another night with lows at or below
freezing temperatures will finally recover to near climo for
Sunday`s high temperatures.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...The primary caption for his period is
`Milder With Light Rain Showers Monday Night`. The short-wave
ejecting NE across Texas tonight, forced to move by the diving
trough along the west coast, will de-amplify as it migrates into
the southern Ohio Valley and Virginia Appalachians Sunday
evening. Water vapor channel indicates/confirms this solution is
now underway. A cross- sectional analysis from the vantage
point of our forecast area, shows pronounced 925-750 mb moisture
advection on westerly trajectories late Sunday night. Upper
support appears weak although it is highly kinetic aloft, as we
become positioned near the entrance region of a jetlet Monday
night. This coupled with the expected moisture may result in
light showers, but if so, overall a light QPF output this
period. At the surface, high pressure will slip offshore by
Sunday evening. The resulting warm-air advection, will bring
warming of 12-16 degrees fahrenheit Monday morning, compared to
the chilly air early Sunday morning, thus noticeably milder
daybreak Monday.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 300 PM Saturday...Moisture poised to advect into the area on
Tuesday, perhaps rapidly, ahead of a decelerating front that may
stall over the region. The GFS is quickest with the moisture
advection and is likely too fast. Will ramp POPS more in accordance
with slower guidance like the EC and Canadian, both implying a
Tuesday night into Wednesday rain event. The rain seems to shut off
on Thursday as low pressure developing off Hatteras helps to push
the boundary to our south. There may not be much to scour out cloud
cover while we are in this wedge-like setup. Moisture will then
further increase in a prefrontal southwesterly flow regime on
Friday. This front may arrive on Saturday, with rain chances
seemingly limited to FROPA and not so much ahead of it.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
As of 06Z...VFR conditions expected through the period. We do
expect plenty of mid level ceilings in time emanating from the
storm across the Mississippi Valley. There may also be a brief
period of MVFR BR in Lumberton and Florence similar to this
morning.

Extended Outlook...Sunday VFR. Unsettled weather Monday through
Thursday morning as a near stationary front moves in and out of
the region.

&&

.MARINE...
NEAR TERM /THROUGH SUNDAY/...
As of 915 PM Saturday...A little jet of westerly breezes which
gusted at high as 15 knots north of Cape Fear appears to be
weakening according to latest buoy data. No significant changes
are needed to the forecast for the remainder of the overnight
period. Discussion from 300 PM follows...

Benign marine conditions will prevail through the near term
period. A ridge of high pressure currently exists across the
coastal plains. The ridge will shift east through tonight and
Sunday resulting in a period of light wind. Seas will be 2 to 3
ft this evening, then subside to 2 ft or less later tonight and
Sunday.

SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 200 PM Saturday...A changeable but manageable marine
period as winds transition from NE to SW Sunday night as high
pressure over the area slips offshore. As the high offshore
drops farther south, straddling Florida and the Bahamas, winds
will become more westerly. The west winds will begin to increase
to 15 KT and gusty Monday night, as the high interacts with
deepening low pressure to our north. With offshore winds
however, inshore seas will remain relatively docile, with
exception of moderate choppiness off the Brunswick coast Monday
night, with the winds paralleling shore there. Due to lack of
swell energy this period, and offshore wind, sea heights
generally this period will hold at 2 feet or less, except 3-3.5
feet Monday night across the outer waters. A few light
rainshowers can be expected late Monday night, but should not
restrict visibility a great deal. No fog or TSTMS expected.

LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 300 PM Tuesday...Westerly wind on Tuesday as high
pressure roosts in the Bahamas and Florida peninsula. A cold
front will drop into the waters and likely stall Tuesday night
as a wave of low pressure develops to our west. This low remains
fairly flat as the boundary sinks to our south on Wednesday
allowing a NE wind to spread southward across the waters.
Northerly winds will veer as Thursday progresses as the day
initially starts with a wedge of high pressure that weakens
later in the day.

&&

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

&&

$$
SYNOPSIS...MBB
NEAR TERM...TRA/SRP
SHORT TERM...MJC
LONG TERM...MBB
AVIATION...SHK
MARINE...


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