Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 231054

Area Forecast Discussion
National Weather Service Wilmington NC
658 AM EDT Fri Mar 23 2018

High pressure will build in across the area through early
Saturday. A quick moving system will move across the area late
Saturday and Sunday. Strong High pressure will build in from
the northeast for much of next week before a warming trend
finally begins late in the period.


As of 330 AM Friday...Freeze Warning will be allowed to continue
and will expire at 9 am. Will send out an updated NPW shortly.
No pcpn expected this period but clouds will increase from the
NW to SE, starting out with High-level Cirrus and eventually
Mid-level Altocu or High Stratocu late tonight. The FA will
remain under the spell of a longwave upper trof, with it`s north
to south axis remaining off the Carolinas Coasts. Models do
indicate a progression of the longwave pattern eastward with an
upper ridge on the doorsteps from the west. The mentioned clouds
are from a mid-level s/w trof that undermines the upper ridge
and more or less gets swallowed up by the dry air associated
with the upper ridge. As for max/min temps, the FA should see
55 to 60 for todays highs, and 35 to 40 for tonights lows. The
possibility for a widespread freeze has diminished for Saturday
morning. However, Frost Advisory conditions are possible which
will roughly depend on low sfc dewpoint depressions and winds
near calm and negligible clouds. The best location for this to
occur will be the NE portions of the ILM CWA, away from the
immediate coast.


As of 300 AM Friday...An unsettled Saturday will transition to a
clearing but cold Sunday as this winter-like pattern continues.

Deep eastern CONUS trough will gradually shift its axis to the east
this weekend, but will then be reinforced by a shortwave digging
through the upper MS VLY early on Saturday and then racing SE to
become off the North Carolina coast Sunday morning. As this occurs,
a weak wave of low pressure will develop as the surface reflection
of this feature, which will then move along a wavering front stalled
near the southern CWA border. In this setup, moisture will steadily
increase within the atmospheric column due to a combination of moist
advection, isentropic lift, and increasing frontogenesis, the latter
two will combine with at least weak PVA to drive rainfall across the
CWA late Saturday through early Sunday. Forecast profiles show PWATs
climbing towards 1.25 inches coincident with peak isentropic lift
near the 300K surface and some pinched isotherms/enhanced
frontogenesis in the 850-700mb layer. Although the heaviest rainfall
is expected to be just north of the area, widespread stratiform will
have the potential to produce 0.25 to 0.50 inches of rainfall, and
will ramp POP up to categorical north zones, high chance south.

Rainfall will come to and end as the weak low pushes away Sunday
morning and forcing weakens as high pressure wedge builds down the
coast. This will bring a drying of the column, but low-level
moisture will become trapped within the subsidence inversion as is
typical in these wedge setups. Do not expect much sunshine on Sunday
despite decreasing showers, and guidance is likely too warm despite
showing highs only in the low 50s. Highs Sunday may climb only into
the upper 40s far north zones, low 50s to the south, which will be
only a few degrees cooler than the still cold mid to upper 50s
forecast for Saturday. Mins Saturday night will be near seasonable
norms, low to mid 40s, but will drop toward the upper 30s Sunday
night. Depending on how quickly moisture can scour out Sunday night,
some frost will be possible as temps crash into Monday morning, but
attm expect mins will be just warm enough and cloud cover dense
enough, to prevent any frost locally.


As of 3 PM THURSDAY...The extended period will feature considerable
amplitude at the mid levels with an omega blocking pattern
across the conus for a few days. This will keep the period
mostly dry with modifying temperatures. Initially however, a
cold front will be settling south embedded within yet another
deep trough across the northeast. Some isentropic lift may
provide a few cool rain showers Sunday but that`s about if for
the period regarding pops. The entrenched surface high will take
some time to modify and this is reflected in the temperature
forecast/grids. HIghs will be stuck in the 50s Sunday and Monday
warming to the 70s by Thursday which is much closer to normal.
Overnight lows will follow the same trend with middle to upper
30s MOnday and Tuesday morning warming to the 50s by the end of
the period.


As of 12Z...Fairly uneventful day aviation wise. High pressure will
dominate with light northwest flow this morning, a bit gusty this
afternoon. Some high clouds will be moving in by late afternoon as a
warm front approaches the area. Fog is not expected, but some ground
fog is possible. A cirrus ceiling will not allow us to fully radiate

Extended outlook...VFR Fri/Sat. MVFR/IFR/Rain developing
Saturday night and persisting into Sunday. VFR Mon/Tue.


As of 330 AM Friday...The local waters will likely see it`s best
conditions to venture out into the Atlantic today and possibly
most of Saturday before winds and seas pick up.

Looking at mainly offshore winds this period, running 10 to 15
kt nearshore waters, and 15 to 20 kt across the outer waters.
Significant seas will follow suit with range from 1 to 2 ft
nearshore waters and 3 to occasionally 4 ft outerwaters. Winds
and resultant seas with common periods of 3 to 5 seconds, will
both diminish and subside-some tonight and heading into
daylight Saturday. This will probably be as good as it gets
considering whats on the doorsteps after this period.

As of 300 AM Friday...A fluctuating boundary will create
variable wind directions Saturday, but this front will sink
southward followed by gusty NE winds and SCA conditions on
Sunday. As the front moves in the vicinity of the waters
Saturday, winds will vary between NE at 10-15 kts NC waters, to
SE 10-15 kts SC waters, but the exact position of the front will
determine where these varying directions will occur. The front
will get pulled southward as a wedge of high pressure builds
south on Sunday, causing winds to become NE across all waters
with speeds rising to 20-25 kts. This NE surge will push seas to
5-7 ft and an SCA is likely on Sunday, after wave heights
climbing slowly from 1-3 ft to 2-4 ft on Saturday.

As of 3 PM THURSDAY...Surface high pressure anchored well to
the northeast will be the primary player for the extended marine
forecast. With a blocking pattern at the mid levels this
feature will remain in place through most of the period
weakening late. Winds from the northeast of 20-25 knots will be
in place ON Monday. By later Tuesday winds diminish
considerably. The prolonged higher winds will produce
significant seas of 3-7 feet and a small craft advisory is a
good bet based on both winds and seas for a good chunk of the


SC...Freeze Warning until 9 AM EDT this morning for SCZ017-023-024-
NC...Freeze Warning until 9 AM EDT this morning for NCZ087-096-099-


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