Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 230755

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
355 AM EDT Tue Oct 23 2018

A cold front will push across the region later today. High
pressure will follow for much of the second half of the week.
Low pressure will likely approach the area from the southeastern
United States by this weekend.


Some mid-level and high clouds along the Mason- Dixon region
will linger this morning. Plenty of sunshine expected across
most of the region today in part to high pressure offshore the
East Coast.

A dry front will move through the area later today. Behind the
front, high pressure will build in from the northwest. A gusty
northwest wind will ensue, ushering in chilly air. Highs will
reach the middle 60s, prior to frontal passage.


Temperatures will drop into the upper 30s to lower 40s tonight
as skies become clear and cold air advection becomes the main
story with the building area of high pressure.

High pressure will remain in control Wednesday through Thursday
night. Skies will be mostly sunny, but the chill will still
linger in the air as highs each day will only make it to the
lower to middle 50s and lows each night will drop into the
middle 30s.


Friday into Saturday, a coastal storm will approach our region from
the south.  Both the 00Z GFS and Euro have trended quicker bringing
in the initial chances for precipitation around 18Z on Friday (2pm).
The GFS solution keeps the storm slightly further off coast, while
the European model has the storm hugging the east coast and then
moving northward through the Chesapeake Bay and the Delmarva
peninsula. The difference in locations between the models means that
the GFS solution will be slightly drier than the Euro. The GFS would
also bring less precipitation to the Blue Ridge and a lesser chance
for wet snow in the elevated areas. The coastal storm is
expected to move northward along the east coast on Friday and
start to affect our region by the early afternoon periods. The
most significant part of the precipitation will move through
late Friday into Saturday. The best chance for precipitation
will be the overnight periods Friday into Saturday. The exact
track of this coastal storm is still unknown and any change in
position could lead to changes in snow potential for Saturday
evening and precipitation amounts. Temperatures will slowly
trend downwards through next weekend.

Sunday into Monday, the coastal low will shift northeastward out of
the region. Behind the coastal storm, a weak cold front will move
through the region on Sunday. Showers will linger throughout the day
but remain mostly scattered. By Monday, the worse of the weather
systems will have move out of our region and high pressure will
slowly start to build into the region. There is the potential for
some lingering showers and some these showers may produce a few
inches of snow in the higher elevation areas.


Mainly VFR conditions expected through Wednesday. A wind shift
from southwest to northwest is expected behind a cold front
later today. Winds will become gusty Wednesday, as gusts could
exceed 25 knots.

On Thursday, high pressure will continue to be in place over
the region. Winds will be out of the north and could be a bit
gusty at times, with gusts of 15-20 kts possible. Skies will be
mostly clear with VFR conditions expected.

A coastal storm will approach the region on Friday. Rain is likely
to start during the after noon . Winds will pick up out of the south
as the coastal system approaches. SubVFR conditions will be possible
especially for southern and central VA

On Saturday, the coastal storm will move through the region early on
Saturday. Wind directions will vary but the general flow will become
northerly leading to cooler air being transported into the region.
SubVFR conditions possible.


A lull in the winds expected this morning before the gradient
increases ahead of an approaching cold front. The best low level
winds and mixing appear to be over northern waters so SCA in
effect north of North Beach on the Bay and north of Indian Head
on the tidal Potomac.

NW pressure surge should push winds well into SCA range during
the evening, diminishing over sheltered waters overnight but
persisting over open waters through the night. A few gusts to
near gale force are possible immediately behind the front. SCA
will likely need to be extended into Wednesday.

Gusty northerly winds on Thursday under mostly clear skies.
Current forecast is for wins to gust to SCA criteria, so an SCA
may be warranted on Thursday.

On Friday, a coastal storm will approach the region. Winds will pick
up over the water leading to the need for small craft advisories.
Rain will be likely as the system approaches.

Saturday, the coastal system will move through early on Saturday.
Rain along with strong winds will be possible. Winds will pick up as
the system moves through leading to the need for continued small
craft advisories.


MARINE...Small Craft Advisory until 6 AM EDT early this morning for
     Small Craft Advisory from noon today to 6 AM EDT Wednesday for
     Small Craft Advisory from 6 PM this evening to 6 AM EDT
     Wednesday for ANZ537-542.
     Small Craft Advisory until 6 AM EDT Wednesday for ANZ534-543.
     Small Craft Advisory from noon today to midnight EDT tonight
     for ANZ535.
     Small Craft Advisory until noon EDT today for ANZ537.
     Small Craft Advisory from 6 PM this evening to midnight EDT
     tonight for ANZ536.


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