Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Wakefield Virginia
1004 PM EDT Sat Apr 19 2014

Synopsis...
low pressure will track off the southeast coast tonight through
Monday...as high pressure builds from the northern Great Lakes
eastward across New England and off the coast. A cold front will
cross the area Tuesday afternoon into Tuesday night.

&&

Near term /until 6 am Sunday morning/...
low pressure will continue to swirl just off the Georgia/SC CST through tonight
while hi pressure settles southeast into new eng. Light rain has
diminished across southern Virginia. A band of -ra has filled in over eastern
NC...and clips mainly Bertie Colorado. Will go with a likely pop for
Bertie...and continue to keep a border of low probability of precipitation elsewhere across NE
NC through the rest of the night. Otherwise...drying from the north will lead
to clearing of middle-clouds north-S (to near the Virginia-NC border)...though
broken cirrus is likely to linger based on current satellite trends. NE
winds will remain gusty (to about 25 kt) near the CST...especially S. Low temperatures from
the l40s inland and on parts of the Eastern Shore...to the M/u40s in
coastal southeast Virginia/NE NC.

&&

Short term /6 am Sunday morning through Tuesday/...
low pressure will continue to be slo to move east of the southeast CST into Monday.
Combo of that low and surface hi pressure east of new eng will be continued low level
flow from the NE. Significant amount of cloudiness expected to remain over mainly coastal southeast
Virginia-NE NC through sun...while elsewhere avgs p/msny. Onshore winds will
remain gusty (to 25-30 kt) near/at the CST. Hi temperatures sun ranging from
55 to 60 at the CST...to 65 to 70f inland/Piedmont.

Upper level ridge builds over the region Sun night through Monday west/ low pressure
continuing to move out to sea. Improving conds expected over coastal NE NC
(albeit sloly)...W/ clear-pcldy weather elsewhere. Cold front tracking into the
Ohio Valley Monday afternoon...continues to the east (and over the mountains Tuesday mrng). That
fnt brings incrsg cloudiness from west-east Tuesday...along west/ next chance at rain. Most
of if not all precipitation may hold off until afternoon west...and evening east on Tuesday.
Continuing west/ slight chance thunderstorm...though dynamics weakening west/ time as fnt
enters the region. Low temperatures Monday night from the m40s to around 50. Hi temperatures
Tuesday ranging from 75 to 80f inland...to the u60s to l70s at the CST.

&&

Long term /Tuesday night through Saturday/...
near seasonable normal temperatures and dry conditions will highlight
the extended period forecast. A cold front will approach the
region late in the extended period.

Trough axis will align along the middle-Atlantic coast Tuesday night-
Wednesday morning. Additional energy will dive down the backside of the
upper trough (aided by 110+ knots jet streak) Wednesday afternoon...likely
only resulting in middle-level cloudiness. Sprinkles may be possible
over the Eastern Shore. Trough will exit the coast Wednesday afternoon as
diffluence aloft Ushers in surface high pressure. Flow will amplify as
a western Continental U.S. Trough progresses eastward into the plains Thursday. An
associated cold front will reach the Ohio Valley Thursday night-Friday
morning. High pressure will slide over the region Thursday...locating
off the southeast coast Thursday night-Friday. A warm front will lift over
the region Thursday night into Friday...as the cold front reaches the
local area late Friday into Friday night. Spatial and timing differences
exist with respect to frontal timing...as well as the evolution of the upper
flow...so confidence is not high at this time. As a
result...predictability is rather low so have only included
slight chance probability of precipitation Friday night.

Near seasonable daytime temperatures Wednesday and Thursday behind the front in
part to northwesterly flow. Highs generally in the upper 60s to near 70.
Warmer Friday and Sat with SW-west flow...highs in the middle-upper 70s.

&&

Aviation /02z Sunday through Thursday/...
strengthening low pressure off the Florida coast will continue to track east-northeast
off the southeast coast through Sunday. Upper level clouds will be
persist over the forecast area through Sun afternoon. Drying high pressure
continues to build in from the northwest...helping to keep precipitation to the
south of kecg.

Strong NE flow...gusting 25-30kt...sun as high pressure north of the
area moves east and wedges south into the middle-Atlantic as the low
pressure system off the Florida coast moves north and helps tighten
the pressure gradient over VA/NC.

Outlook...a cold front will push across the region Tuesday/Tuesday
night...with VFR conds returning Wednesday as high pressure builds into
the region.

&&

Marine...
high pressure will continue to build over southeast
Canada...ridging southward over central Virginia. Meanwhile...surface low pressure
remains nearly stationary off the southeast coast. The result is ongoing
NE flow over the waters. Seas have dropped off slightly over the
northern waters...right around 5 feet...but Small Craft Advisory conditions persist over
the coastal waters. Coastal low will drift slightly northeastward
tonight...strengthening the pressure gradient over the waters. The
result will be slightly increasing northeasterly winds over the waters to
15 to 25 knots. As a result...Small Craft Advisory headlines have been expanded to
include the Northern Bay zones. However...only marginal conditions
expected...so have not included the York and Rappahannock
River...but gusts to 20 knots are possible near the mouth of the
rivers. Small Craft Advisory conditions will continue through sun and into Sun night.
Increasing/persistent northeasterly winds sun-Sun night will build seas to
6-9 feet...up to 10 feet in the southern coastal waters. High pressure will
push off the NE coast Sun night-Monday as the coastal low lifts
farther NE. Winds will become more northerly and diminish as a result.
This will allow seas to finally begin to subside...but remain 4-7
feet through the day Monday. Small Craft Advisory headlines have been extended through Monday
(fourth period) as a result. Flow backs around to the south Tuesday
in advance of a cold front set to cross the region Tuesday afternoon-
evening. Seas will likely drop below 5 feet Monday night-Tuesday with
speeds falling at or below 15 knots. However...Small Craft Advisory conditions again appear
possible behind the front Tuesday night-weds.

&&

Akq watches/warnings/advisories...
Maryland...none.
NC...none.
Virginia...none.
Marine...Small Craft Advisory until 6 am EDT Monday for anz632>634-638.
Small Craft Advisory until midnight EDT Sunday night for
anz630-631.
Small Craft Advisory until 6 PM EDT Monday for anz650-652-654-
656-658.

&&

$$
Synopsis...alb/tmg
near term...alb/tmg/ajz
short term...alb/tmg
long term...Sam
aviation...dap
marine...Sam