Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Wilmington NC
424 am EDT Thursday Apr 17 2014

Synopsis...
a wedge of high pressure will linger across the Carolinas today
through Friday. Rain chances will increase during the weekend as an
area of low pressure moves up along the southeast coast. Another
ridge of high pressure will settle across the Carolinas the first
part of next week.

&&

Near term /through tonight/...
as of 420 am Thursday...water vapor imagery notes dry middle layer air
in place across the Carolinas...while infrared imagery shows some low
clouds working onshore across southeast NC and near Georgetown. Low level
trajectories will direct the offshore low level moisture into the
area during the day and tonight. Meanwhile...southwest flow aloft
will direct some higher level moisture this way as well. The trend
for today will be mostly clear to partly cloudy with increasing
clouds during the day and tonight. A surface ridge will hold across
the Carolinas with cool northeasterly flow in place at the surface.
Although temperatures will be warmer today compared to yesterday
they will remain a few categories below normal. The aforementioned
increasing low level moisture will aid in warmer mins tonight...
especially along the coast where lows are expected to be in the middle
to upper 40s. Farther inland mins will range from 40 to 45.

&&

Short term /Friday through Saturday night/...
as of 420 am Thursday...low pressure will ride up along the
southeast coast Friday into the weekend as high pressure remains
wedged in. Models were still diverging as to the exact track and
intensity of this low but overall expect increasing lift through
late Friday into Saturday to produce increasing clouds and pcp. The
greatest quantitative precipitation forecast may end up being just off shore where trough extends up
through. Still looks like best chance of pcp will come late Friday into
early Saturday...but clouds and pcp may linger through much of the
weekend as this low moves up the coast. GFS looks to the be the
fastest solution but has trended further inland also. Will increase
pcp chances Friday afternoon into Saturday showing a greater chance inland to
account for continued uncertainty.

Temperatures should hold int the 60s on Friday and may end up being lower
than forecast if clouds and pcp overspread the area earlier.
Dropped the highs for Saturday to account for increased cloud
cover and pcp. Although if pcp ends and skies clear...temperatures could
jump into the 70s. Overnight lows will be closer to 50.

&&

Long term /Sunday through Wednesday/...
as of 420 am Thursday...low pressure system will be departing off to
the east northeast as high pressure ridges down from the north
behind it. Expect drying trend through Sunday into Monday with
coastal areas the last place to clear as low clouds and light pcp
may linger depending on how quickly the low moves away. There is
still considerable disagreement between the models with respect to
the speed of the system but should see gusty northerly winds on the
back end bringing drier air in...especially Sun night into Monday.
GFS brings pcp water values down less than a half inch until late
Tuesday when next front approaches the area from the W-NW. The
shortwave will push this front east through the coastal Carolinas
Tuesday evening. Not much in terms of upper level support to produce
anything but showers. As system progresses east high pressure will
build down behind it. Overall warming trend early to middle week. Middle
to upper ridge builds up the East Coast Wednesday and Thursday with height
rises leading to some of the warmest temperatures of the extended period.

&&

Aviation /06z Thursday through Monday/...
as of 06z...11-3.9u satellite imagery and surface observation indicate some
marine stratocu is beginning to reach the coastal terms. Ceilings being
reported now are above 3kft...so will add VFR ceilings to kilm/kmyr/kcre
through daybreak. Tempo MVFR cannot be ruled out...but it does not
appear likely at this time. Kflo/klbt should remain clear overnight.
Northeast winds at or below 10 kts will strengthen during the day...becoming
10-15 kts with gusts of 20 kts. Expect scattered/broken stratocu during the
day with VFR ceilings increasingly likely along the coast after 18z.
Northeast winds will remain around 10 kts through the evening hours.
The coastal terms could see MVFR ceilings develop by the end of the taf
period.

Extended outlook...expect at least periods of MVFR/IFR ceilings Friday
and Saturday as well as increasing rain chances. MVFR ceilings could
linger into Sunday. VFR on Monday.

&&

Marine...
near term /through tonight/...
as of 420 am Thursday...the northeast fetch will continue from the
early morning hours through Thursday night. Winds will be highest
away from the coast and as a result the outer waters will likely see
a continuation of small craft wave conditions. The Small Craft
Advisory has been extended into the short term period given the
persistence of the northeast fetch. Seas will be lowest along the
Brunswick County inshore waters where the fetch is blocked.

Short term /Friday through Saturday night/...
as of 420 am Thursday...wedge of high pressure will persist through
Friday into Saturday as low pressure rides up along the southeast
coast. Overall expect persistent NE flow greatest off shore and
decreasing closer to the coast to near 15 kts but latest wna and
model runs show winds holding up as tightened gradient holds Friday
into Saturday as low pressure strengthens as it moves up along the
southeast coast and off to the northeast by the end of the weekend
as a reinforcing shot of cool and dry high pressure moves in. Local
waters may briefly diminish Friday night into early Saturday before
ramping up again toward the latter half of the weekend in northerly
winds.

Long term /Sunday through Monday/...
as of 420 am Thursday...strong northerly flow on back end of
departing low pressure system through early next week will keep the
winds and seas up above Small Craft Advisory thresholds most likely. Will be highly
dependent on how strong and fast the low moves off further to the
east-NE through the latter half of the weekend as high pressure builds
in behind it. Winds may reach up to 25 to 30 kts once again Sunday
into Monday. This may kick seas up to 8 to 10 feet in local waters
through Sun night. Winds and seas will diminish as low moves farther
away on Monday. Expect seas to drop below Small Craft Advisory thresholds by Monday afternoon.

&&

Ilm watches/warnings/advisories...
SC...none.
NC...none.
Marine...Small Craft Advisory until 6 PM EDT Friday for amz250-252-
254-256.

&&

$$

Near term...srp
short term...rgz
long term...rgz
aviation...srp/bjr