Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wakefield Virginia
1012 PM EST Monday Nov 30 2015
low pressure off the North Carolina coast will lift north tonight
through Tuesday...pulling the front back across the area as a warm
front. A cold front will cross the region Wednesday into Wednesday
evening. Cool high pressure will build across the region for the
latter portion of the week into the weekend.
Near term /until 6 am Tuesday morning/...
previous forecast remains on track. Dropped low temperatures tonight down a
degree or two in some spots but other than that still expecting
periods of -ra/-dz. Patchy fog is possible as well but mainly
expecting low stratus.
late this afternoon...one weak low was over eastern Kentucky while a second weak low
was off the NC CST. A frontal boundary connected these two lows
and extended down across SC. Meanwhile...hi pressure was centered just off
the New England CST. Latest radar showed scattered areas of light rain
and drizzle over the County Warning Area. This cool air wedge will dominate the weather
tonight into early Tuesday morng...with a cloudy sky and off and on light
rain or drizzle. Lows will range from near 40 west-northwest...to the lower 50s
near/along the CST.
Short term /6 am Tuesday morning through Thursday/...
during Tuesday...weak low pressure just off the southeast Virginia CST...will lift north-northeast
just off the Delaware-Maryland-Virginia and southern New Jersey csts...pulling the frontal boundary
back across the area as a warm front. Meanwhile...a cold front will
push through the Ohio and Tennessee valleys and into the mountains this will
result in the highest probability of precipitation for rain shifting into the northern half of
the region. Winds turning to the west then SW will help maximum temperatures
climb into the middle 50s to lower 60s (except lower 50s extreme nw).
Tuesday night into Wednesday night...the cold front will approach from the west Tuesday
night into Wednesday morng...then cross the area and move off the CST Wednesday
afternoon/Wednesday night. South-southwest winds in advance of the front will help temperatures
climb into the middle 60s to near 70 over much of the area on Wednesday
before showers accompany the front. Total quantitative precipitation forecast for this event from
tonight into Wednesday eveng...will range from around .25 inch over NE NC...to
1.0-1.5 inches over northern and western counties. The front pushes
offshr/out to sea Wednesday eveng/ngt...with northwest winds ushering
drier/cooler air into the region behind the front. Lows Wednesday night
will range from the upper 30s to upper 40s. Hi pressure will then build in from
the west on Thursday...providing a sunny/mostly sunny sky and maximum temperatures in
the lower to middle 50s.
Long term /Thursday night through Monday/...
medium range period characterized by progression from departing
upper troughing over the eastern Seaboard toward the split flow
regime currently in place across the western Continental U.S.. closed upper low
will push east from northern New England toward Atlantic Canada, with
broad high pressure at the surface and aloft building east from the Ohio
Valley. Meanwhile, models are in good agreement at this time that southern
stream shortwave energy will push across the southeast coast...with
development of any surface features likely to occur along and off
the southeast coast. This would keep any associated rain chances off
the Carolina coast over the weekend. This will translate to dry weather
through the weekend into early next week. An upper low is prognosticated to
develop out west in The Four Corners region by late in the weekend,
pushing east into the Ohio Valley by Monday night. This will likely
result in some increasing clouds/rain chances toward the middle of
Temperatures for the period slowly trend upward...from near normal
at the beginning of the period to around 1 St dev above normal by
early next week.
Aviation /03z Tuesday through Saturday/...
low pressure developing off the coast east of the Virginia/NC border will
move slowly north through Tuesday. This will influence the wind
direction with winds turning to west/northwest by Tuesday at all sites
IFR/LIFR conditions continue widespread as of 00z...except at ksby
where ceilings are currently MVFR. Recent trends as well as MOS data
indicate the ceiling will soon go back to IFR at sby during this
evening. North/northwest winds in the Hampton Roads area were helping to
improve visibility to VFR/MVFR but low ceilings continue. Expecting the IFR
ceilings to hold overnight but some of this may lift to MVFR southeast portions
during the day Tuesday.
Outlook...periods of rain and IFR conditions continue Tuesday night
with gradual improvement Wednesday. A cold front sweeps from west to
east across the Middle Atlantic States Wednesday evening. A period of
dry and VFR weather takes over Thursday through Saturday.
latest observation reflect north-northwest flow across the waters this aftn, with winds
steadily dropping off as gradient slackens between cool air wedge of
high pressure inland and low pressure trough off the southeast coast.
Continue to note some areas of fog creating diminished visibility in
the lower James/ches Bay. Hrrr/narre continues to indicate visibility
will gradually recover from north to S...and some improvement is being
seen on traffic cams. Therefore will hold off with a headline for
dense fog. Instead, will look at another marine weather statement for
local visibility below 1 sm through early evening. Small Craft Advisory over the Bay will be
dropped with the afternoon package for the ches Bay (except mouth of
the Bay zone). Small Craft Advisory flags continue, mainly for hazardous seas, for
all Atlantic coastal waters through Tuesday...and through Tuesday night over
northern waters. Nwps and wavewatch handle wave heights similarly
overnight in the 5-7 feet range along the coastal zones...2-3 feet in
the ches Bay (3-4 in the mouth of the bay). Seas subside a bit
tomorrow...4-6 feet...before dropping below Small Craft Advisory theresholds
gradually tomorrow evening/Wednesday morning. This, too is handled
similarly by 12z/30th nwps and wavewatch...and a blended solution
has been used for seas in the near/short term.
Winds will continue to gradually weaken initially tonight, and will
back to the west-northwest over the Bay and southern coastal waters as low pressure
takes shape just off the northern Outer Banks. Farther north, winds
will remain east-NE tonight, before becoming west-SW by midday Tuesday/Tuesday afternoon
as the low slides NE away from the area. Winds become southerly and
increase again (still sub-sca) tomorrow night as gradient again
tightens ahead of an approaching cold front. That cold front will
cross the waters late Wednesday afternoon through Wednesday eveng. South-southwest winds will turn to
the northwest Wednesday night...with colder air expected to move in behind the
front Thursday and Thursday night. Significant pressure rises and decent cold
surge looks to bring strong Small Craft Advisory conditions early Thursday morning through
midday Thursday. Potential remains for a period of marginal gales across
the northern coastal waters...and will need to monitor potential for gale
headlines for this time frame. Winds diminish back below Small Craft Advisory
thresholds by Friday as high pressure builds in from the west and
remains across the middle-Atlantic region through the early next week.
Marine...Small Craft Advisory until 6 am EST Tuesday for anz634.
Small Craft Advisory until 6 PM EST Tuesday for anz654-656-658.
Small Craft Advisory until 5 am EST Wednesday for anz650-652.