Area Forecast Discussion
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FXUS62 KILM 230523
Area Forecast Discussion
National Weather Service Wilmington NC
120 AM EDT Thu Mar 23 2017
Freezing temperatures are expected over portions of the area
tonight as strong Canadian high pressure builds south. As this
high moves offshore Friday and during the weekend, a significant
warm-up will ensue. Minor rain chances are expected Sunday as a
weak upper disturbance passes well to our north.
.NEAR TERM /THROUGH THURSDAY/...
As of 900 PM Wednesday...Scattered to broken mid clouds were
eroding from the N this eve as strong chilly high pressure
centered across the Great Lakes continued to build across the
Carolinas. Skies will be mainly clear overnight.
Temps were still in the 50s at mid eve. However, with clear
skies and lighter winds overnight, we still expect lows to drop
into the 30s. Across North Carolina, all but coastal areas are
still expected to drop to near or just below freezing and a
Freeze Warning will continue. Across South Carolina, lows
should remain above freezing and so no Freeze Warning has been
issued. Frost is not expected throughout given the dry air.
Dewpoints still vary significantly across the Forecast Area.
Dewpoints were in the 20s across our inland zones while still in
the mid 30s to mid 40s at the coast at mid eve. Dewpoints will
level out in the 20s throughout overnight with lower 30s confined
to portions of the immediate coast.
Wind speeds will remain in the 5 to 10 mph range inland overnight.
At the coast, where the gradient was tightest, winds were still
gusting in the 15 to 20 mph range this eve. Wind speeds at the
coast overnight should decrease to 5 to 15 mph as high pressure
Thursday will be dry and unseasonably cool as the coldest air
moves overhead. Expect highs only in the mid to upper 50s.
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...Cold Canadian high pressure will move
eastward shifting from the Mid Atlantic coast farther off shore
through Fri. This will allow a return flow to set up with
increasing moisture and warmth. Initially, though, the dense
shallow cold air mass in place will set the stage for very cold
temps once again Thurs night. Models are showing a coastal
trough becoming more defined overnight Fri as high pressure
wedges in over inland areas with lighter NE winds while just off
shore a more easterly wind develops pushing moisture on shore.
Most places should be a few degrees warmer than previous
night...mid 30s for the low, but would expect some
traditionally cooler spots to drop toward freezing. The moisture
return will bring RH values above 80% overnight Thurs and this
will allow some frost to develop under decent radiational
cooling conditions as skies remain mainly clear and winds drop
off Thurs eve. Upon the expiration of the Freeze Warning for
tonight, there will be an evaluation as to which counties would
need an frost advisory or possibly another Freeze Warning. The
most likely candidates would be Pender and Bladen counties, but
other spots mainly across NC could surely see frost if forecast
remains on track.
As high pressure shifts farther off the Mid Atlantic coast on
Friday, a southeasterly return flow will bring warmer and
moister air into the area while a deeper SW to W flow will
develop aloft. Mid to upper ridge will build up the southeast
coast with heights rising and 850 temps return up near 7C Fri
aftn. This will push temps back up toward normal...closer to 70
most places. The on shore flow will keep places closer to the
cooler waters in the 60s. There may be some clouds around, but
pcp will remain at bay through the period and overall there will
be a good deal of March sunshine. Temps on Fri night will remain
at or above normal.
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 300 AM Wednesday...Return flow underway on Saturday
expected to bring unseasonable warmth. Upper ridge axis should
stay close enough to the coast to keep mid levels fairly dry.
This changes fairly quickly Saturday night into Sunday and
moisture depth may increase. Two large shortwaves try to impinge
upon our upper ridge but appear to largely be shunted over it
to the north. It appears that late period moisture depth may
actually decrease. So while some minor late weekend rain chances
may materialized they should dwindle heading into next week.
Daytime highs will remain above climo, generally in the mid to
upper 70s but trending towards 80 inland late in the period.
Nighttime lows will similarly be mild, and the deviations from
climo will tend to mirror the degree of cloud cover.
.AVIATION /06Z THURSDAY THROUGH MONDAY/...
As of 06Z...Skies have cleared and will remain so through the TAF
cycle. Similarly there will be no visibility restrictions so the
entire forecast will feature VFR. Wind will remain out of the NE to
E as high pressure remains to our north.
Extended outlook...Fog possible Thursday night. Otherwise VFR.
NEAR TERM /THROUGH THURSDAY/...
As of 900 PM Wednesday...Small Craft Advisory will remain in
effect through Thursday as a cold and dry surge works south.
Conditions will begin to moderate Thu afternoon as the center
of a chilly airmass gains proximity and the pressure gradient
slackens. Expect ENE to NE winds of 20 to 25 kt diminishing to
15 to 20 kt during Thu. Seas will peak in the 4 to 7 ft range
and then begin to subside during Thu.
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...High pressure will shift farther off
the Mid Atlantic coast through the period. This will allow a
return flow to set up with winds shifting around from NE Thurs
evening to E-SE through Fri and southerly by Sat morning. The
models are hinting at a coastal trough overnight Thurs which
may act to produce enhance a more NE flow near the coast with a
greater easterly flow off shore. Either way, an on shore flow
will be the rule through much of the period diminishing to 10
kts or less. This will allow seas to subside from near 3 to 4 ft
Thurs eve down to 3 ft or less Fri morning.
LONG TERM /SATURDAY THROUGH MONDAY/...
As of 300 AM Wednesday...The above normal temperatures will
give a clue as to expected marine conditions. That is, the area
will be in a return flow regime around sprawling Atlantic high
pressure. Wind will thus be southerly and for the most part be
capped at 10 kt though a few higher gusts certainly hard to rule
out. A minor increase in the long shore swell energy could make
for an increased presence of 4 ft seas along the outer portions
later Sunday in an otherwise 2 to 3 ft wave environment.
NC...Freeze Warning from 4 AM to 9 AM EDT Thursday for NCZ087-096-
MARINE...Small Craft Advisory until 5 PM EDT Thursday for AMZ250-252-