Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 161356
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
856 AM EST Sun Feb 16 2020

.SYNOPSIS...
A weak wave of low pressure developing off the coast will
spread scattered showers across the eastern Carolinas today.
This system moves offshore Monday. Shower chances increase on
Tuesday in advance of a cold front and again Wednesday as the
front pushes south. Final chance of rainfall Thursday as low
pressure develops to the south. Canadian high pressure will
build into the Carolinas late this week bringing colder
temperatures and dry weather.

&&

.UPDATE...
Only minor changes to the hourly temperatures. No significant
changes in how the near term forecast unfolds.

&&

.NEAR TERM /THROUGH MONDAY/...
Today will be highlighted with increasing, thickening and
lowering cloudiness with stratiform light rain increasing in
coverage by sunset today. There-after looking at
areas/widespread light rain with pockets of moderate rain likely
along the immediate coast. An inverted sfc trof/coastal front
has become established just offshore and parallel to the
Carolina Coasts. Do not anticipate this sfc feature to move
onshore given the current and progged mid-level flow. A weak
embedded low amplitude vort, within the southern westerlies,
will move east along the Gulf Coast today, reaching the SE U.S.
Coast tonight and continuing east and away from the ILM CWA Mon.
The interaction with the coastal trof and dynamics associated
with the mid-level s/w trof, will result in increased rainfall
across the ILM CWA. QPF amounts from the current time thru
sunset Mon, suggests around 0.15 inches along and west of
I-95...to 0.30 inches along the immediate coast. Trended lower
for todays Max temps due to widespread cloudiness blocking any
direct insolation. Kept tonights lows and Mon maxes in line
with latest model MOS Guidance.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
Low pressure developing along a coastal trough will be
positioned off the NC coast on Monday night and slowly trek to
the north and east overnight. Limited remaining moisture will
keep shower chances low, but clouds will significantly affect
overnight low temperatures. Deep southwesterly flow will
develop by midday Tuesday and moisture advection will increase
across the area. This will lead to a decrease in cloud cover
early as winds shift from northeasterly to southwesterly
followed by an increase in cloud cover and shower chances late
in the day. During SW flow events, significant cloud cover is
difficult to develop. This, along with the slight tilt in the
upper-level pattern and the fetch of SW winds, should keep highs
in the low to mid-70s despite guidance showing a fight for 70.
Small and weak perturbations in the large-scale upper-level flow
will lead to weak shower activity across the Southeast into the
Carolinas, increasing Tuesday afternoon as the max PWs advect
into the Carolinas at around 1.5 inches. Cold front approaching
the area will help with the development of more widespread
shower activity Tuesday night into early Wednesday.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Arctic high pressure will build into the central US and push
a cold front through the Carolinas on Wednesday. As the center
of the high is so far to the north and west, expect an
afternoon/evening frontal passage which will maintain highs
in the 60s before the front actually makes it to the area.
This later frontal passage could lead to increase in rain
chances, especially in our southern communities. Cold
front will stall over the Gulf coast through the FL
panhandle and up the US East Coast on a line along the
eastern edge of the Gulf Stream. A lack of dry air advection
will keep clouds around Wednesday night into Thursday
morning and lows will be at the mercy of available shallow
cold air advection under cloudy skies.

Upper-level jet streak will be largely responsible for low
pressure development off the coast of GA during the day on
Thursday with high confidence based on the baroclinic SFC
conditions likely to be in place. This will lead to the
development of areas of heavy rainfall on Thursday afternoon
with higher confidence in the southern half of the CWA.
Previous model runs of both the GFS and ECMWF have hinted at
wintry precip associated with this low pressure system.
Unfortunately, the cold air moving into the area is likely
to be limited to a thin layer near the surface, leaving a
bulbous area between 925-750 mb well above freezing. A lack of
dry air also limits the potential of reaching the freezing mark
through evaporation or other latent heat processes. Sorry, snow-
lovers. Cold air will continue to chase the moisture associated
with the low pressure system as it moves ENE over the North
Atlantic and the propensity for cold air to stall behind our
western mountains will limit any chance of seeing an isolated
flurry as the low zips away. Have adjusted high temps down a
couple of degrees as winds on the north of the deepening low
should provide a constant source of cold air advection
throughout the day.

High pressure will build in solidly overnight Thursday into
Friday with northerly winds 10-20 mph and a few gusts to 25 mph
expected. Temps at 850 will plummet to -8C to -11C across the
area and morning lows will drop to below freezing despite the
breezy conditions. Cold and dry air will dominate the pattern at
the end of the week with below normal conditions likely Friday
and Saturday. The air mass modifies on Sunday and we expect
temps to be near their climo mark, or slightly above, as the
high stalls overhead.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
High pressure will give way to a weak low that will track northeast
along the coast later today. A VFR stratocu ceiling will hang in
through much of the day, lowering to MVFR toward evening. Weak
isentropic lift will cause light to moderate rain to break out,
mainly at the coastal terminals. IFR ceilings are a good bet through
the overnight hours.


Extended Outlook...Intermittent clouds and pcpn Mon thru Thu
will result in sub-VFR conditions at times. A strong cold front
will sweep across the Carolinas late Thu, followed by improving
VFR conditions.

&&

.MARINE...
Today thru Mon:
The development of the coastal front is ongoing and location
just offshore and parallel to the Carolina Coastlines south of
HAT. The low amplitude s/w trof will not be enough to pull that
coastal front onshore and therefore winds will stay from the
NE-E. Wind speeds will increase due to the tightening sfc pg but
should stay below SCA thresholds thruout this period. Expect
reduced visibilities from stratiform light to pockets of
moderate rain later this aftn but mainly during this evening and
overnight time line. During Mon, whats left of the coastal
front, will wash out leaving weak ridging to affect the FA.
Significant seas will commence in the 2 to 4 foot range with the
main input coming from a 9 second period Easterly swell. With
increasing wind driven waves today thru tonight, overall seas
will build to 3 to 5 ft, mainly occurring late today thru
tonight.

Mon Night thru Tue Night:
Improving seas on Monday night as low pressure moves away from
the coast and the pressure gradient relaxes. Southwesterly flow
develops during the day on Tuesday ahead of the next cold front.
Winds will remain 10-15 knots ahead of the front with shower
chances likely ahead and during the cold front passage Wednesday
and Wednesday night. As the front pushes through the area,
expect the front to stall along the eastern edge of the Gulf
Stream. Overnight Wednesday, winds will increase along this
stalled front. High pressure building over the central US will
help with the development of a low pressure system off the GA
coast during the day on Thursday. Shower chances will increase
rapidly throughout the day and winds will increase to 20-25
knots with gusts to near 30 knots. This could bring Small Craft
Conditions as seas increase to 4-6 feet with occasionally higher
waves. Unidirectional flow Thursday night will maintain rough
seas as wind speeds slightly increase.

&&

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

&&

$$

UPDATE...RH
NEAR TERM...DCH
SHORT TERM...21
LONG TERM...21
AVIATION...DCH
MARINE...DCH/21



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