National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KLWX 231350
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
950 AM EDT Sat Sep 23 2017

.SYNOPSIS...
Surface and upper level high pressure will remain in place through
the weekend and into early next week. The high will slowly
weaken its grip over the area by the middle of the week as
Hurricane Maria moves northward through the Western Atlantic.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Aside from a tiny patch around SHD, all early morning fog has
burnt off. No changes required to the going forecast. It will be
another largely sunny and unseasonably warm day. Highs should
be at least a couple degrees warmer than yesterday...mostly in
the mid 80s. Overnight, another possibility for patchy fog to
develop with lows mainly in the 60s, except in the urban
centers, where temperatures may stay around 70.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
On Sunday and Monday, the upper ridge is at its strongest over
our area, which should also yield the warmest (dare I say
hottest?) temperatures of this stretch. Can`t rule out that we
hit 90 in some spots. Even 89 degrees would be the warmest we
have seen in over a month. Dewpoints will start creeping upward
too, and that means uncomfortable humidity levels for late
September, but nothing to spark any precipitation through Monday
night.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The long term period will be dominated by attention to Hurricane
Maria. On Tuesday, ridge axis will be to our north, with Maria
pushing northwest from the south. Latest guidance has shifted a bit
west somewhat, bringing the storm closer to the North Carolina Outer
Banks than previous runs. Guidance now stalls the storm just
southeast of the Outer Banks Wednesday before the next strong upper
trough and cold front moving in from the northwest finally starts
kicking it out to sea on Thursday. While most guidance still does
not show a significant impact in our region, attention should
continue to be paid to this storm until it moves safely out to sea.
Please refer to the latest products from the National Hurricane
Center for the most up-to-date information on Hurricane Maria.

Behind the cold front (which could bring a few showers regardless of
what Maria does), temperatures will drop significantly Friday into
Saturday. The long September warm spell looks likely to end.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
VFR with light winds and just a few clouds through the valid
TAF period, and continuing through Monday. Only exception will
be perhaps some early morning low clouds/fog, primarily
affecting CHO/MRB.

Attention will be on Hurricane Maria during Tuesday and Wednesday.
While sub VFR conditions are not likely, a gusty northwest breeze of
15-20 knots is possible, as are a few showers. A further deviation
northwest in the track of Maria could bring worse conditions. Refer
to latest NHC statements for up-to-date information on Maria.
-- End Changed Discussion --

&&

.MARINE...
High pressure will allow for light winds around 10 knots or less
through the weekend. Perhaps some patchy fog on the waters
overnight.

SCA winds looking likely across the waters on Tuesday and Wednesday
as Hurricane Maria approaches and we get enveloped by its expanding
wind field. A few showers will also be possible. If the storm`s
track deviates further northwest, more significant impacts are
possible (though not likely). Refer to latest NHC statements for up-
to-date information on Maria.

&&

.TIDES/COASTAL FLOODING...
-- Changed Discussion --
September is always a prime month for tidal flooding and this
is proving to be no exception. Minor coastal flooding is
forecast to persist through this morning`s tide cycle and likely
this afternoon`s tide cycle from Annapolis southward on the
western shore of the Bay and on the lower tidal Potomac. Since
departures have not yet decreased, needed to add Washington DC
and Alexandria to the list of sites requiring Coastal Flood
Advisories; went for today and tonight for starters.

Straits Point (St. Mary`s Potomac side) will likely continue to
see tidal flooding around high tide through at least the Sunday
afternoon tide cycle. Elsewhere, things are more in question
due to the light winds. Local research has shown that in light
wind regimes, the tidal anomaly locally is more controlled by
what`s coming in to the lower Bay. Those anomalies are currently
higher than what we have locally, and seem unlikely to drop
much, so our forecast might prove to be optimistically low on
Sunday/Monday.
-- End Changed Discussion --

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...Coastal Flood Advisory until 2 AM EDT Sunday for DCZ001.
MD...Coastal Flood Advisory until 10 PM EDT this evening for MDZ018.
     Coastal Flood Advisory until 1 AM EDT Sunday for MDZ014.
     Coastal Flood Advisory until 9 PM EDT this evening for MDZ017.
VA...Coastal Flood Advisory until 2 AM EDT Sunday for VAZ054.
WV...None.
MARINE...None.
-- End Changed Discussion --

&&

$$
SYNOPSIS...JE
NEAR TERM...JE/HTS
SHORT TERM...JE
LONG TERM...RCM
AVIATION...JE/HTS/RCM
MARINE...JE/RCM
TIDES/COASTAL FLOODING...JE/HTS