Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Wakefield Virginia
935 PM EST Mon Jan 23 2017
low pressure lifts northeast just off the northern mid Atlantic
coast tonight and southern New England coasts through Tuesday.
The low then moves away from the New England coast Tuesday night
into Wednesday, as high pressure builds into the area. A cold
front crosses the region Thursday morning.
Near term /until 6 am Tuesday morning/...
update...sfc low picked up a decent amount of forward speed this
evening as it moved off the Cape Hatteras coast and over the
ocean. Its central pressure is located about 120 miles east of
Ocean City, Maryland as of 915 PM this evening, and it will continue
to track nnewd overnight. Have seen a short-lived surge in winds
(primarily along the ocean side of the Maryland/Virginia eastern shore) this
evening with winds occasionally gusting to 35-40 mph. This is
due to a pseudo-dry slot rotating over these areas with a
90-100kt jet aiding in the ability to mix stronger winds down
over the waters...especially as the mid/upper level low and
shortwave energy enhances instability aloft. The combination of
the elevated instability with low stratus ceilings in place will
continue rain shower/drizzle chances areawide this evening,
which will then become focused more newd after midnight as the
upper low moves offshore and a deformation zone sets up across
the nrn neck/peninsula and Maryland/Virginia Eastern Shore. Only minor
tweaks needed to ongoing forecast.
latest GOES water vapor imagery centers anomalous upper level
low pressure over central North Carolina. Plume of moisture
visible just offshore of the mid-Atlantic coast, spreading
northward into the northeast. At the surface, ~990mb low
pressure has organized over eastern North Carolina, with the
triple point offshore. Earlier clearing across the southeast
forecast area has filled back in as low clouds have pivoted back
over the area. Brunt of the precipitation has pushed north of
the local area, with another area of convection observed across
southeast North Carolina. For the local area, light
precipitation persists from the Piedmont into central Virginia.
Light precipitation will continue to pivot across central
Virginia as the anomalous upper low lifts into the region and
the surface low deepens just offshore. Convection to the south
progged to push toward the North Carolina coast as the local
area remains stable. Have removed any mention of thunder this
evening, but due to the strength of the cold pool, cannot rule
out a few rumbles across northeast North Carolina late afternoon
into the evening.
The surface low progged to locate just offshore of the Delmarva
through late tonight as moisture pivots around the backside of
the stacked low. Have retained likely pops across the northeast
half of the local area through late tonight. Additional rainfall
amounts through tonight will generally be less than one quarter
of an inch. Lows forecast in the upper 30's to low 40's inland
to mid 40's near the coast under a cloudy sky. Northwest wind
generally 10-15 mph with gusts to 25 near the coast.
Short term /6 am Tuesday morning through Thursday/...
upper level low pressure lifts northeastward away from the mid-
Atlantic coast Tuesday as an upper level ridge builds in from
the west. At the surface, low pressure lifts along the northeast
coast as high pressure builds over the eastern Gulf of Mexico,
ridging northward into the Ohio Valley. Expect some lingering
light precipitation Tuesday morning across the Eastern Shore due
to energy in the northwest flow aloft and lingering moisture.
Dry elsewhere, with clearing skies through the day. Breezy, with
highs in the upper 40's northeast to mid 50's inland.
Upper/surface ridge axis locates over the region Tuesday night,
resulting in a clear sky and lows in the mid to upper 30's to
low 40's. Ridge axis slides offshore Wednesday as the next upper
trough approaches from the west. An associated cold front
progged to reach the central Appalachians late Wednesday. Return
flow will push highs into the low to mid 60's (approaching upper
60's inland). Clouds increase late Wednesday and Wednesday
evening ahead of the approaching cold front. Spatial and timing
differences exist, but general model consensus pushes the front
through the region early Thursday morning. A potent shortwave
accompanies the front along with a narrow band of high
precipitable waters. However, the NAM and sref are holding out
on the moisture return so have kept probability of precipitation in the chance range
(30-40%). Front quickly pushes offshore Thursday afternoon, with
dry conditions expected area wide during the afternoon. Mild
Thursday morning with lows in the upper 40's to low 50's.. highs
Thursday generally in the mid to upper 50's.
Long term /Thursday night through Monday/...
a broad trough of low pressure is expected to enter the region
Wednesday night and into Thursday as a surface cold front slides
into the area. Moisture still appears somewhat limited as the front
crosses the region Thursday morning. Continuing to lean closer to a
drier solution with the highest precipitation chances confined to
far southeast portions of the area Thursday morning.
Behind the cold frontal passage Thursday morning, an upper level
trough builds into the eastern half of the US allowing for northwest
flow to dominate the forecast period. Temperatures will return to
more seasonable values by Friday and continue through Monday. Highs
will generally be in the low/mid 40s with lows in the upper 20s to
lower 30s through this period. The positive tilt configuration of
the upper level trough will allow for high pressure to build in from
the south and suppress precipitation chances through Sunday. Models
are hinting at a reinforcing cold front passing through the region
on Monday, but it appears as though moisture will be limited with
Aviation /03z Tuesday through Saturday/...
strong north to northwest winds and poor flight conditions
continue. Winds are strongest at sby where gusts over 30 knots
will continue through the evening. Winds turn to northwest and
remain breezy (especially near the coast) through Tuesday.
Widespread IFR/LIFR ceilings continue this evening which will
slowly improve overnight but remain IFR into Tuesday morning.
Visibilities will improve more quickly. Scattered showers will
occur through Tuesday morning associated with an upper level low
moving north from the Carolina coast. High pressure builds in
later Tuesday with VFR conditions taking over.
Outlook...high pressure builds into the area for Tue evening
into Wed. There will be a chance for showers Wed night into Thu
associated with a cold front with dry conditions expected for
Thu aftn through Sat.
815 PM update...a dense fog advisory is in effect until 1 am
EST for the southern Chesapeake Bay and the coastal waters from
Cape Charles to the Virginia/NC border. A few gusts around 35kt will
also be possible through roughly 1000 PM to midnight from
Fenwick Island to Parramore Island.
a broad area of low pressure will move NE along the mid Atlantic
coast thru tonight. Gradient winds have starting to ease across
the northern coastal waters and will be able to replace the Gale
Warning with an Small Craft Advisory as of 4 PM. Will still have gusts to 30 kt
across the northern coastal waters thru this evening and into
the overnight hours as winds back from east to north then northwest by early
Tue morn. Seas of 7- 15 ft north of Parramore Island will remain
elevated this evening before gradually subsiding to 5-9 ft by
As alluded to above, the broad low moves slowly NE tonight and
will be very slow to lift to the NE along the New Jersey coast Tuesday.
Meanwhile, high pressure builds in from the northwest. The wind becomes
north-northwest and increases to 15-25kt (gusts to ~30kt possible early
Tuesday with the strongest pressure rises) for the Bay/ocean
later tonight into Tuesday, with speeds averaging 15-20kt for
the rivers/sound, with 25kt gusts possible. Scas are now in
effect for all waters thru tues aftn or Tue night. Seas will be
slow to subside on Tue and may not drop below 5 ft until early
High pressure gradually builds into the region Tuesday night and
slides offshore Wednesday ahead of a cold front. This cold front
crosses the coast later Wednesday night into early Thursday. High
pressure builds in from the west Thursday night into Friday.
a high surf advisory remains in effect for the Maryland beaches
thru 1 am and Accomack County Virginia thru 10 PM. Some minor beach
erosion is expected.
Minor tidal flooding is currently ongoing from Wachapreague to
Ocean City on the Atlantic side. Minor flooding is expected for
portions of the west side of the Chesapeake Bay this evening.
This is in response to lingering effects of the strong easterly
flow from early today.
As low pressure slowly moves NE up the coast tonight and
Tuesday, winds will become gusty from the northwest late tonight into
Tuesday. This will cause the excess water on the west side of
the Bay this evening to move back east and impact areas adjacent
to the Easter side of the Bay during Tuesday morning. Additional
coastal flood advisories have been issued to highlight this
Maryland...high surf advisory until 1 am EST Tuesday for mdz025.
Coastal flood advisory until 7 am EST Tuesday for mdz024-025.
Coastal flood advisory until 2 am EST Tuesday for mdz021>023.
Virginia...high surf advisory until 10 PM EST this evening for vaz099.
Coastal flood advisory until 10 am EST Tuesday for vaz099-100.
Coastal flood advisory until 11 PM EST this evening for vaz075-
Marine...Small Craft Advisory until 1 am EST Wednesday for anz654-656-
Dense fog advisory until 1 am EST Tuesday for anz632-634-656.
Small Craft Advisory until 6 am EST Wednesday for anz650-652.
Small Craft Advisory until 1 PM EST Tuesday for anz635>638.
Small Craft Advisory until 4 PM EST Tuesday for anz630>632-634.
Small Craft Advisory until 4 PM EST Tuesday for anz633.