Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 200054
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
754 PM EST Sun Nov 19 2017

.SYNOPSIS...
High pressure will control area weather through Monday.  A coastal
trough and approaching cold front may bring some showers late
Tuesday and Tuesday night. Low pressure is expected to develop in
the eastern Gulf of Mexico mid week and may bring unsettled weather
to the eastern Carolinas Thursday and Friday as it moves northeast.
High pressure early next weekend will be followed by the passage of
a cold front next Sunday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 8 PM Sunday...Have added Columbus County to the Frost
Advisory although this is expected to be a marginal event due to
very dry air over the forecast area. Patchy Frost is a good bet
here and there overnight, but widespread frost may be tough to
get given dry low levels. Previous discussion from this
afternoon follows:

Surface high pressure will build in under a northwest flow
aloft. The airmass is once again just cold enough to cause some
frost/freeze concerns as a good part of our area remains at
least officially in the growing season. It appears via guidance
and some residual low level mixing that any freeze conditions
will be a stretch. There is enough of a threat/concern for frost
especially late when the winds diminish. Will go ahead and
issue a frost advisory for areas where mins are 35 degrees and
under. This will preclude most of the coastal areas. Overnight
lows will general be in the middle 30s. Highs Monday will be
middle to upper 50s under mostly sunny skies.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...High pressure previously overhead takes on a
very west-east elongation Monday night bringing a light onshore flow
to coastal areas, especially SC. The ocean influence paired with the
radiational cooling inhibition could add a few degrees to the
seasonably cool nighttime lows. Neither should hold true over NW
zones and there may be a large than normal NW to SE gradient in low
temps, those areas ending up almost as cool as the previous night.
On Tuesday warm advection will both shoot highs back to climatology
if not a few degrees warmer but also yield increasing cloud cover
and some slowly increasing rain chances.  These rain chances appear
to increase and shift from inland to the coast Tuesday night as the
WAA interacts with stronger vorticity centers in the SW mid level
flow. The WAA and cloud cover will keep Tuesday night lows elevated
a good 10 degrees above climatology.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 PM Saturday...Lingering rain is possible early Wednesday as
an upper trough moves out and a cold front moves out to sea. Another
short wave trough could spawn low pressure development along the old
front off the southeast U.S. coast.  This will bring another chance
of rain to the area Wednesday night into Friday, though the exact
details of this scenario are still in doubt. Dry weather is expected
for the remainder of the long term but light showers are possible
with another frontal passage and vigorous upper trough on Sunday.

Temperatures will be near seasonal normals of mid 60s Wed before
falling back into the mid to upper 50s for Thu and Fri. Slightly
warmer temperatures are expected Sat and Sun with highs in lower
60s. Mins temperatures Wednesday night will fall to the upper 30s to
lower 40s with higher numbers SE and along the immediate coast.
Temperatures in the mid 30s to around 40 are expected Thu night and
Friday night before rebounding to the mid to upper 40s Saturday
night.

&&

.AVIATION /01Z MONDAY THROUGH FRIDAY/...
As of 23Z...VFR through the period as surface high pressure
builds in from the west. Light northerly winds will veer to the
ENE late Monday afternoon along the coast, but remain variable
inland near the center of the high.

Extended Outlook...VFR conditions are expected Sunday through
Tuesday morning. MVFR conditions may develop in low clouds and
light rain Tuesday night through Wednesday morning, then MVFR
to IFR conditions are possible Thursday night into Friday in low
clouds, rain, and fog.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 8 PM Sunday...Have dropped Exercise Caution headlines for
our southern 3 marine zones as conditions continue to improve.
For AMZ250 we are just barely within criteria with 15 to 20 kt
winds and 3 to 5 ft seas, but expect this too will improve by
around midnight. Previous discussion from this afternoon
follows:

Winds and seas on the way down this afternoon as although cold
air advection continues, the stronger low level wind fields were
ahead of the front that has long since passed. North to
northwest winds of 15-20 knots will prevail most of the late
afternoon hours and night. On Monday surface high pressure
settles over the area and winds decrease dramatically, down to
the single digits by late afternoon. Seas are down to just over
six feet at 41013 and I will wait til the last minute but most
likely cancel the small craft advisory just a touch early and
issue an exercise caution statement. Overall seas will settle
into a 2-4 foot range overnight and even less later tomorrow.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Things just about as quiet as they get for the
marine environment for most of the period. West-east elongated high
pressure to keep just a light onshore flow of just a few knots. A
weak coastal trough will develop on the periphery of the high later
Tuesday into Tuesday night veering flow to SE and adding a few knots
of wind speed, bumping the forecast up a category or more. Seas will
be following suit, showing a gradual growing trend.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 300 PM Saturday...N to NE winds INVOF 15 KT are expected
through much of the period though a peak of 15 to 20 KT is possible
Thu night into Friday. On the open waters, seas of 3 to 5 feet are
expected through the period. Depending on low pressure development
off the SE U.S. coast, conditions in this period could be hazardous
and it is possible that winds and seas could exceed thresholds for
Small Craft Advisories, 25 KT winds and/or seas of 6 FT, during this
period.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Frost Advisory from 4 AM to 9 AM EST Monday for SCZ017-023-024-
     032-033-039-053.
NC...Frost Advisory from 4 AM to 9 AM EST Monday for NCZ099.
MARINE...None.

&&

$$

SYNOPSIS...99
NEAR TERM...REK/SHK
SHORT TERM...MBB
LONG TERM...RAN
AVIATION...CRM
MARINE...REK/MBB/SHK/RAN


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