Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 181332
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
932 AM EDT Mon Sep 18 2017

.SYNOPSIS...
Warm high pressure will remain over the eastern United States
this week. Meanwhile, Hurricane Jose is expected to track
north off the Mid Atlantic coast tonight through Wednesday.
Refer to the National Hurricane Center`s website hurricanes.gov
for the latest on Jose.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
An upper-level ridge will remain over the eastern United States
today while surface high pressure over New England wedges down
into the Mid-Atlantic.

Low level moisture trapped underneath the subsidence inversion
has resulted in areas of low clouds and fog. The fog in
sheltered valleys west of the Blue Ridge Mountains should burn
off by late this morning. Areas of low clouds will gradually
dissipate late this morning into early this afternoon...but a
broken cu deck will develop for most areas due to the higher
amounts of low-level moisture.

More warm conditions are expected today along with breaks of
sunshine. Max temps will be in the lower 80s across most
locations. Limited instability underneath the subsidence
inversion may be enough for a couple popup showers west of the
Blue Ridge Mountains...but coverage will be isolated and most
areas will be dry.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
By tonight, the forecast will begin to be influenced (indirectly) by
Jose, although the bigger influence (again, relatively speaking)
will be felt on Tuesday. Northeast/north winds will increase
tonight, especially near the Bay, with a fair amount of cloud cover
east of the Blue Ridge as well. Will be bringing a chance of showers
inland to the western shore by dawn Tuesday, with better chances
during the day on Tuesday. The inland reach of these showers likely
won`t spread west of I-95, but that is an aspect that is highly
conditional on the track of Jose, as well as how much the storm
expands as it weakens. A slight nudge westward would increase the
potential that an outer band could spread inland, providing a
soaking rain.

Am still keeping a solution of subsidence in the wake of the
cyclone, which will affect the forecast area Tuesday night and
Wednesday.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Ridge of high pressure surface and aloft will build over the
region Thu through Sun as Jose remains well offshore. Tranquil
conditions are expected as a result. Temperatures will remain a
few degs above normal during this period. By early next week,
the ridge begins to weaken as a weakening post- tropical Jose
likely completes another loop and heads back to the mid-Atlc
coast. We`ll also be watching Hurricane Maria move into the
southwest Atlc during the second half of the week. Recent trends
indicate Maria may stay out to sea, but it is really too early
to tell at this time. Please refer to NHC for the latest on Jose
and Maria.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
Low clouds underneath the subsidence inversion has resulted in
MVFR cigs this morning. MVFR cigs will be slow to
lift...gradually turning to VFR conditions during the early to
middle afternoon hours.

Jose will make its nearest pass to the terminals late tonight
through Tuesday. Significant impacts will likely remain to the east,
but northeast winds tonight suggest there may be another round of
low clouds to deal with.  VFR should prevail Tuesday afternoon
through Friday, aside from perhaps early morning fog.

&&

.MARINE...
The gradient has strengthened a bit...and there have been a few
reports of gusts around 18 knots across the middle portion of
the Maryland Chesapeake Bay and the lower Tidal Potomac River.
A Small Craft Advisory is in effect for these areas today...but
it will be marginal. The gradient will strengthen more tonight
and SCA conditions are expected across these areas. By Tuesday,
the gradient will be at its strongest, with several model
solutions suggesting the gales will be possible on the mid Bay.
That is contingent on the track of Jose. Have added a Small
Craft to all Maryland and DC waters on Tuesday since confidence
in 20+ kt gusts high. Would not rule out an upgrade to Gale
Warning for a portion of this area.

Winds should stay generally below SCA Wednesday through Friday
under ridge of high pressure.

&&

.TIDES/COASTAL FLOODING...
Water levels continue less than a foot above astronomical
predictions. This trend should gradually increase over the next
couple of days. At this point, St George Island will be the only
site forecast to consistently exceed minor flood.

Based on strong confidence in the trends, have extended the Advisory
for St Marys County for another three tide cycles, through the
daytime cycle Tuesday. Elsewhere, model spread precludes action at
this time. While moderate flood possible at sensitive locations,
confidence in this outcome at the low end of the spectrum.

Elevated water levels likely to be a concern through the end of the
week.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until 4 PM EDT Tuesday for MDZ017.
VA...None.
WV...None.
MARINE...Small Craft Advisory from midnight tonight to 8 PM EDT Tuesday
     for ANZ531-539.
     Small Craft Advisory from 6 AM to 8 PM EDT Tuesday for ANZ530-
     535-536-538.
     Small Craft Advisory until 8 PM EDT Tuesday for ANZ532>534-537-
     540>543.

&&

$$
SYNOPSIS...HTS
NEAR TERM...BJL/HTS
SHORT TERM...HTS
LONG TERM...LFR
AVIATION...BJL/HTS
MARINE...BJL/LFR/HTS
TIDES/COASTAL FLOODING...BJL



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