Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
302 am EST Wednesday Dec 11 2013
high pressure moves off the middle Atlantic coast later today. A dry
cold front crosses the area tonight. Canadian high pressure builds
into the region Thursday...then moves off the coast Thursday night
and Friday. Low pressure approaches from the southwest Saturday.
Near term /today/...
high pressure builds over the area ahead of an approaching cold
front. Few if any clouds expected. Despite full sun...850 mb temperatures
support highs from the u30s to m40s.
Short term /tonight through Friday night/...
models agree in moving a dry cold front across the area this evening.
Little in way of clouds expected. Lows in the 20s to near 30 southeast.
Another in a series of 1040+ mb high pressure systems tracks from
the nations middle section into the eastern states Thursday / Friday.
Given the origins of this airmass and the fact that we now have
some snow coverage to the west...have kept high temperatures below guidance
through the period. 850 mb temperatures support highs Thursday in l-m30s north
and m30s-near 40 South. Ridge axis builds over the region Thursday
night. Cold with lows upper teens - m20s. A slow warming trend begins
Friday as the highs shifts east. Highs 40-45.
Models differ on timing of next system ejecting NE out of Texas Friday
night. NAM/sref/ECMWF a bit slower keeping precipitation west of forecast area Friday night.
GFS the outlier and spreads some moisture across the area by 12z
Sat. Kept it dry but indicate increasing clouds. Lows u20s-m30s.
Long term /Saturday through Tuesday/...
models agree that temperatures remain at or below normal through the period.
Leaned toward the slower 00z European model (ecmwf) solution with respect to this weekends system.
Low pressure prognosticated to track from the middle/lower MS valley late Friday night...
NE to just off the New Jersey CST by sun morng. This low and an
associated cold front will bring more rain to the region Sat through Sat
night. The precipitation will end over southeast cnties early sun morng...as the
front pushes out to sea early Sun afternoon. Hi pressure will build back into
and over the area for late Sun night into Tuesday. Min temperatures will be in
the upper 20s to lower 30s Sat morng...range from the lower 30s to the middle
40s sun morng...then range from the lower 20s to the lower 30s Monday and
Tuesday morngs. Maximum temperatures will range from the lower 40s northwest to the upper 50s
southeast Sat...range from the middle 40s to middle 50s sun... range from the upper
30s to middle 40s Monday...then range through the 40s Tuesday.
Aviation /08z Wednesday through Sunday/...
cold front has pushed well offshore tonight as high pressure
builds in from the west. Moisture has also scoured out as dew
points continue to drop into the middle-upper 20s. This will be the
trend through early Wednesday morning...further limiting fog development
regardless of good radiational cooling (clear skies) and wet
soils. The exception will be along the immediate coast...but
expect ksby to remain VFR through Wednesday morning. Otherwise...weakening
gradient will produce westerly winds at or below 10 knots.
For today...expect sunny skies except for few-scattered passing high
clouds at or above 25k feet this afternoon. As high pressure nudges in...surface
winds will become northwesterly this afternoon before high pressure moves
offshore...backing the winds to the SW. However...winds will
remain at or below 10 knots.
Outlook...a stretch of dry/VFR weather conditions is expected
Thursday/Friday with a chance of rain returning over the weekend.
cold front has pushed well offshore early this morning as high
pressure builds in from the west. A weak Lee/thermal trough exists
over central Virginia as high pressure nudges in around the trough. This has
produced westerly winds over the water early this morning. With the high
still to the west...seeing modest cold air advection over the water this morning.
However...the gradient has relaxed...so expect speeds to remain sub
Small Craft Advisory. Seas remain 3-4 feet. High pressure will continue to build over
the Carolinas today as winds briefly turn to the northwest...before the
high moves offshore late today-early tonight backing the winds to
the SW. A weak/dry cold front will cross the waters early
tonight...with the 850 mb front lagging slightly behind. The strongest
cold air advection will arrive after midnight tonight...with winds becoming northwest 15
to 20 knots over the Bay and 20 knots over the coastal waters. Confidence
is high at this time that the Bay will experience Small Craft Advisory conditions...but less
confident over the coastal waters and eastern Virginia rivers. Strongest
gradient winds will occur just behind the front...but models suggest
the gradient will begin to relax shortly thereafter Thursday morning
(925mb winds diminish to 20-25 knots middle morning thurs). Latest
guidance also keeps the rivers under Small Craft Advisory conditions...so will hold
off on Small Craft Advisory headlines at this time. Across the southern coastal waters and
sound...gradient is not forecast to be as strong...so speeds
forecast to remain below Small Craft Advisory conditions. Wavewatch also builds seas
to 5+ feet for the southern coastal zones (south of the bay) Thursday late
morning-afternoon (3rd period)...but with the aforementioned weaker
gradient...will limit seas to 4 feet at this time. High pressure and sub Small Craft Advisory
conditions return Thursday night-Fri. Unsettled conditions return this
weekend as low pressure lifts over the region.
dox radar remains down until further notice due to comms problems.
Local telco continues to work on the problem. Further updates will
be passed along as they become available.
Marine...Small Craft Advisory from 1 am to 6 PM EST Thursday for