Scientific Forecaster Discussion
fxus62 kilm 221637 cca
Area forecast discussion
National Weather Service Wilmington NC
1137 am EST Thu Feb 22 2018
high pressure holding offshore, will bring Spring-like weather
until a cold front arrives Monday. This front should bring a chance
of rain, followed by temperatures returning closer to normal early
next week. A warming trend with increasing rain chances Wednesday
and Thursday can be expected, as low pressure approaches from the
west next week.
Near term /through Friday/...
as of 1022 am Thursday...interesting 'differential heating'
boundary/convergence line inland tracking north, a few drops
under it but the narrow, linear feature, has not measured
anywhere, per meso-net and ASOS/AWOS scans. Will keep low end
probability of precipitation here, but convergence should weaken along this meso-scale
feature. As inland stratus transitions to cumulus, weakning the
differential heating circulation. Re-shaped sky grids to show
more clouds western zones versus eastern zones today. Diurnal
cumulus should become widespread, though immediate coastal zones
will receive mostly sunny conditions and sea breeze cooling.
Will take a look at maximum temperatures well inland where this
thick overcast remains very much intact still.
As of 300 am Thursday...dense fog advisory until 10 am. Much of
the same for the forecast through tonight as Bermuda ridge
remains offshore. This will produce a warm and humid southerly
return flow across the area while maintaining plenty of
subsidence and dry air aloft. The very shallow moisture will
once again carry areas of fog through the morning commute
lifting by mid morning with only some strato cu left by late
morning. Subsidence inversion holds around 4-5k ft and therefore
do not count any showers with strato cu mainly between 3500 to
5k ft this afternoon.
Temperatures will once again cruise into the 70s reaching around
80 most places except for the beaches which will experience a
cooler sea breeze. Records are once again poised to be broken
with Wilmington record of 78 in 2003, Florence 80 in 1990,
North Myrtle Beach 75 in 2007 and Lumberton 78 in 2003.
Going with persistence again tonight will lead to areas of fog
with some patchy dense fog developing through the early morning
hours. Any nocturnal showers over the waters will be spotty at
best and therefore do not count on any brushing up over the
land. Overnight lows will drop to between 55 and 60 most
Short term /Friday night through Saturday night/...
as of 300 am Thursday...upper ridge and sfc ridging will continue to
be the main features controlling the area's weather this period.
Friday will basically be a persistence fcst based on the previous
several days. However, Saturday will begin to see the upper ridge
flatten somewhat along with the magnitude of the sfc ridging retreat
back to the east. Successive mid-level short waves will keep trying
to erode the upper ridging as they remain well west but just north
of the forecast area during Sat. Have increased Sat pops to a low chance across
inland counties and have them becoming more isolated across the
coastal counties. For Sat, clouds and possible pcpn may shave off
several degrees from the days progged highs but nevertheless, this
period's Max/min temp fcst will continue to run an amazingly 20
degrees above normal, in Feb no less!! have hit the land fog hard
Friday night but not as hard Sat night due to cloudiness. Sea fog
could partially move onshore Friday thru Sat and will continue with
prefixing the sea fog with patchy except areas for a few hrs Friday
Long term /Sunday through Wednesday/...
as of 300 PM Wednesday...the record-breaking upper level ridge
should retrograde back into the Gulf of Mexico and across
Florida by Saturday. An upper disturbance across the plains
states should damp out as it moves east into the ridge Sunday
and Monday, but should still knock heights down enough to allow
deep moisture pulled off the western Gulf of Mexico to reach
the area Sunday night through Monday.
Bermuda high pressure at the surface will remain off the
Carolina coast through Sunday while continuing to advect an
unseasonably warm and humid airmass into the area. A few record
high temperatures will be possible again Saturday and Sunday.
Sunday's record high of 79 in Florence looks particularly
By Sunday, increasing moisture ahead the front and the
disappearance of the subsidence inversion should spread these
showers chances down to the coast as well. The front itself
should cross the area Monday morning, finally pushing the
tropical airmass out of the area. Long-range models show rain
chances peaking behind the front Monday morning as a ~12 hour
period of isentropic lift overrunning the frontal surface
develops aloft. Once the front pushes down into Georgia the
drier, cooler air from the north should become deep enough to
dry our weather back out, with more seasonable temperatures
expected for Tuesday and Wednesday.
It's interesting to note that the tremendous negative temperature
departures we rang up in early January (15-25 degrees below
normal for seven consecutive days) will almost be cancelled out
by the exceptional warmth we're experiencing now (february
20-25). Since december's temperatures averaged near normal, it's
likely the meteorological winter of 2017-2018 will go down in
the record books as "near normal" for average temperature...
despite the roller coaster ride we've been on seeming anything
Aviation /18z Thursday through Tuesday/...
as of 18z...persistent pattern continues. Look for scattered cumulus
this afternoon. A few cells could produce a sprinkle, but that is
about it. Light winds tonight with mostly clear skies. Fog will once
again form around 08-09z, heaviest around 11z. Friday, becoming VFR
by 14-15z, with light southeast flow. Increasing cloud at the end of
the forecast period.
Extended outlook...morning IFR/br possible through Sat am. Showers
and MVFR conditions possible Sunday through Monday, drying
near term /through tonight/...
as of 1022 am Thursday...wave spectra show southeast waves 3-4 ft every
7 seconds, 2-3 feet inshore. No significant changes made, but
look for wave periods to increase to 9 seconds later today,
easing steepness a little bit. Primary hazard remains sea fog
and potential for reduced visibilities.
As of 300 am Thursday...Bermuda high pressure remains in control
with warm and humid light southerly flow mainly 10 kts or so.
This will once again produce areas of fog over the cooler shelf
waters overnight. Have issued a marine weather statement for
patchy dense fog across the waters through the morning. Seas
will remain right around 3 ft most waters.
Short term /Friday through Saturday night/...
as of 300 am Thursday...models indicate the re-positioning of the
sfc ridge axis extending from the high's center, slightly southward
each day. This will result in a slight veering of the winds to a
more southerly direction Fri and a south-southwest-SW direction for Sat. The sfc
pg will remain somewhat relaxed on Fri and begin to slightly tighten
during Sat. Thus will go with around 10 kt speeds Fri and 10-15 kt
for Sat. Significant seas will run 2 to 3 ft or around 3 ft Fri into
Sat. During this time, the east-southeast ground swell at 9+ second periods
will dominate. For late Sat, 4 to 5 second period wind waves will
begin to influence the sig. Seas, resulting in 4 footers possible l
ate Sat. Sea fog will be hit hardest on fro of the 2 days. As winds
veer to a SW direction, this will cut down on the fetch for the fog
to develop. The local waters from Cape Fear south to Little River
Inlet, this coastal configuration will see the best chance for the
fog to reach the immediate coast.
Long term /Sunday through Monday/...
as of 300 PM Wednesday...unseasonably well-defined Bermuda high
pressure will maintain a south-southwesterly wind across the
waters Sunday. The approach of a cold front from the west Sunday
should accelerate winds to around 20 knots during the day.
There's at least a chance conditions could reach Small Craft
Advisory criteria. The front should finally cross the area early
Monday morning with a shift to northerly winds. Weak high
pressure to our north is expected to push the front down into
Florida Monday night.