Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 170147
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
947 PM EDT Sat Sep 16 2017

.SYNOPSIS...
High pressure will dominate the region through Sunday. Hurricane
Jose is forecast to move north along...but well offshore of...
the Atlantic coast early next week. See the National Hurricane
Center bulletins for the latest information on Jose. High
pressure over New England may extend into our area late next
week.

&&

.NEAR TERM /THROUGH SUNDAY/...
A ridge of high pressure will remain over the eastern United
States through tonight. A small weakness in the ridge remains
over our area in the form of an upper-level low. Instability
under the low has waned with sunset and no further showers are
expected tonight.

An easterly flow will usher in moisture from the Atlantic as
well...and that can be seen currently with dewpoints in the 60s
for most locations. Plenty of moisture underneath the nocturnal
inversion will result in some fog tonight. Fog may be
dense...especially in rural areas and sheltered valleys. Right
now the big question is whether we get dense fog. Given
lingering mid clouds, do not feel confident in a widespread
event, but it will need to be closely monitored overnight.
Clouds are trying to slowly dissipate and in areas where it
clears, fog will be likely.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
Surface high pressure will wedge into the area from the New
England Coast Sunday while a weak upper-level trough remains
overhead within the longwave upper-level ridge. More warm
conditions are expected for this time of year with isolated to
widely scattered popup showers. The best chance for showers will
be near and west of the Blue Ridge and Catoctin Mountains where
terrain circulation may serve as a lifting mechanism.

Jose will track north off the Mid-Atlantic Coast Sunday night
through Monday night. This system is most likely to stay far
enough offshore to prevent any significant impact on our
weather. However...an east to northeast flow around this system
will continue to usher in more moisture across our area. A few
outer band of showers cannot be ruled out...but much of the time
is likely to turn out dry. Please refer to the National
Hurricane Center for updates on the forecast regarding Jose.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Hurricane Jose will be moving north on Tuesday, well
east of the Mid-Atlantic coast. Confidence has increased in its
track, which currently keep its center well offshore with
minimal impacts to our CWA. Current concerns are minor coastal
flooding and/or wind gusts between 30 to 40 mph over the
Chesapeake Bay. The National Hurricane Center is issuing
advisories on Hurricane Jose and can be found at the following
website: http:/www.nhc.noaa.gov.

Jose will continue to track north and then northeast away from
our region Wednesday into Saturday as high pressure builds
into our area. Some afternoon showers possible Wednesday into
Friday due to upper level energy.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
VFR conditions prevail this evening, but areas of fog are
expected overnight into Sunday morning. Fog may be locally dense
with IFR or subIFR conditions possible. The best chance for
dense fog will be across KCHO and KMRB...but there is a high
risk at the other terminals (except probably KDCA) as well, so
added some 2 mile visibilities in elsewhere as well. Given
lingeirng mid clouds, was not confident about going below 2
miles, but some places will likely do so, with 1/4 mile possible
in spots.

A weak onshore flow will continue through Monday night. Areas
of low clouds and/or fog are possible during the overnight and
morning hours each day with isolated afternoon showers.

Tuesday may bring periods of sub-VFR conditions at times due to
showers and/or thunderstorms, with maybe an increase in winds
as Jose moves away from us. Wednesday into Thursday mostly VFR
conditions expected with high pressure building in.

&&

.MARINE...
An onshore flow will continue through Monday...but wind speeds
should remain below SCA criteria, at least through Sunday ight.
Jose is most likely to pass by well offshore Monday night
through Tuesday night. A Small Craft Advisory will likely be
needed for portions of the waters during this time. Will have to
watch Jose...any shift in the track will have a significant
impact on wind speeds. See the National Hurricane Center for the
latest on the forecast of Jose.

Weak high pressure may return for late next week.

&&

.TIDES/COASTAL FLOODING...
A light onshore flow will continue through tonight. Elevated
water levels continue. Most areas should have water levels just
below minor thresholds during the preferred high tide cycle
tonight. However...we expect it to touch minor flooding at
Straits Point so a Coastal Flood Advisory remains in effect.

Later Sunday and especially Monday, the approach of Jose may
further elevate water levels, resulting in minor flooding at
sensitive sites. The nighttime tide cycle is astronomically
preferred. Depending on how close the storm gets, moderate is
not impossible, but uncertainty on this is very high at the
moment.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until 3 AM EDT Sunday for MDZ017.
VA...None.
WV...None.
MARINE...None.

&&

$$
SYNOPSIS...BJL
NEAR TERM...BJL/RCM
SHORT TERM...BJL/RCM
LONG TERM...IMR
AVIATION...BJL/IMR/RCM
MARINE...BJL/IMR/RCM
TIDES/COASTAL FLOODING...BJL/RCM



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