Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington NC
252 PM EST Tuesday Dec 1 2015
a front south of the area will lift north as a warm front tonight.
A cold front will cross the Carolina coast late Wednesday. Strong
high pressure behind the front will bring cooler temperatures late
this week into the upcoming weekend.
Near term /until 6 am Wednesday morning/...
as of 255 PM Tuesday...frontal boundary roughly along the Georgia
South Carolina line will rise north this evening reaching the
Cape Fear region in the pre-dawn hours of Wednesday. Low-level
convergence over the coastal waters associated with this feature
will help spawn showers along the NE SC coast around midnight and
spread north into the coastal interior of southeast NC into very early
Wednesday. Concurrently...the showers along the Appalachian
Mountains and foot-hills will approach the I-95 passageway by
12z or a little after daybreak. 0.10-0.20' of rain could drop
overnight into early Wednesday along our coast and coastal
interior...the bulk of it after 6z. Temperatures will fall slow
this evening and may even rise into the pre-dawn hours as the warm
front and southerly flow arrive...with minimums of middle 50s
inland to the around 60 at the coast.
Short term /6 am Wednesday morning through Thursday night/...
as of 255 PM Tuesday...currently a large storm system is on the move
through the Midwest with an elongated and trailing front moving
to the east through the southeast. This front will slowly move
across the area Wednesday as the middle level system is in no hurry.
I have increased probability of precipitation just slightly from previous forecasts based
on numerical guidance. We still remain just below likely criteria
as does most of the guidance. Only a couple of lightning strikes
to be found currently and since I cant completly rule out a strike
or two Wednesday added slight chance of thunder. Quantitative precipitation forecast amounts
should be one quarter inch or less with an isolated area maybe
approaching 0.50. Some consensus on guidance now with the met
numbers in play for Friday morning and this was the only change to
the temperature forecast...slightly cooler. Expect a partly to
mostly sunny cooler day Thursday.
Long term /Friday through Tuesday/...
as of 255 PM Tuesday...low amplitude middle level troughiness in place on
Friday while surface high pressure keeps things too dry for the
feature aloft to bring any weather. Models are showing cold
advection aloft into this feature mainly to our north. This should
favor an increase in mainly diurnal cumulus fields as middle level
lapse rates steepen over the weekend. This feature moves off the
coast Sunday night into Monday allowing for a brief ridge-building.
The next system will be bearing down on the area from the west
though its timing is poorly agreed upon between various guidance.
Some of the faster solutions imply coastal cyclogenesis by late
Monday whereas the more believable solutions target Tuesday for the
same. In addition to the timing differences there are considerable
differences in the prognosticated strength of the system early next week
with results varying from a rather low quantitative precipitation forecast frontal passage to a high quantitative precipitation forecast
coastal storm. Temperatures will begin the long term a little bit
shy of climatology but show a gradual moderating trend both due to solar
insolation and the building ridge aloft.
Aviation /20z Tuesday through Sunday/...
as of 18z...MVFR/IFR expected today due to low ceilings...areas of fog
and vcsh...with intermittent improvements to VFR possible this
afternoon...especially along the coast. LIFR possible overnight into
the early morning hours...with conditions becoming MVFR on Wednesday
and areas of fog/vcsh.
MVFR/IFR prevails across the area this afternoon...mainly
inland...due to low ceilings and areas of fog...as conditions have
improved to VFR along the coast...though expect pockets of VFR to be
short lived. Expect trend to continue into tonight with vcsh/-ra
possible as a warm front lifts northward through the area. Northeast
winds will become east-southeast this afternoon...at or below 8 kts. Into
the evening hours...low ceilings and fog development will allow for
MVFR/IFR/possible to prevail...with dense fog possible early
Wednesday morning. Again...periods of VFR possible on
Wednesday...otherwise expect MVFR with vcsh and low ceilings.
Extended outlook...expect VFR through the extended period.
near term /through tonight/...
as of 255 PM Tuesday...no caution statement or advisory needed for
tonight. Light NE winds will veer to S overnight into early Wednesday
as a warm front lifts north...increasing to S-south-southwest 10-15 knots by
daybreak...strongest offshore. Marine showers into early Wednesday may
reduce visibility...particularly if accompanied by patchy fog
early Wednesday. Seas primarily 2-3 feet except around 4 feet outer
portion...in a mix of east-southeast waves 1-2 feet every 9 seconds...east waves
2 feet every 7-8 seconds...and an increasing S-southeast chop early Wednesday.
Short term /Wednesday through Thursday night/...
as of 255 PM Tuesday...a decent southwest flow will develop across the
waters Wednesday. Wind speeds will increase to 15-20 knots for a few
hours ahead of the front. This front moves across around 0600 UTC
Thursday with a westerly then northerly flow developing. This flow
of 10-15 knots will continue through the end of the period. As for
seas...heights should remain just below small craft thresholds
Wednesday with 3-5 feet. Seas in the wake of the front drop to 2-4
feet. I have also added some patchy sea fog for part of the day
based on what is taking place currently offshore Charleston.
Long term /Friday through Sunday/...
as of 255 PM Tuesday...wind will remain out of the northeast for the
duration of the long term period. High pressure will be well
established across much of the eastern U.S. On Friday with a broad
center over the Ohio Valley and midatlantic region. There will be a
gradual eastward shift of this high through the period possibly
leading to a slight veer to east-northeast. Most zones will likely experience a
general 15 to 20 knots forecast for most if not all of the period. The
strength of the gradient paired with the relative persistence of the
fetch will keep most of the zones very close to advisory thresholds
through the period.