Area Forecast Discussion
Issued by NWS Sterling, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
FXUS61 KLWX 242256

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
656 PM EDT Sun Sep 24 2017

High pressure will remain in place through the first part of
the week, then slowly weaken its grip over the area by the
midweek as Hurricane Maria moves northward through the Western
Atlantic. A cold front will move through late in the week,
bringing more seasonable temperatures.


High pressure across the Great Lakes extends into the Mid

Dewpoints in the lower to mid 60s should set the stage for
tonight, as skies should remain clear and winds will be light.
Low temperature forecasts follow this cue, with perhaps lows
closer to 70 in the inner cities.


Locally, the synoptic pattern will remain similar through Monday
and Tuesday. Maria turns in the western Atlantic, nearing the
Outer Banks on Monday night, while the ridge overhead becomes
pinched. The only implications to the forecast will be the
extent of clouds spreading inland, and whether there will be
sufficient moisture for any precip. At this point, clouds look
likely Blue Ridge or I-81 east Monday night into Tuesday. Precip
looks iffy...perhaps enough for a 20-30 PoP east of I-95. Of
course, track changes would lead to changes in these details, so
monitoring Maria`s progress via NHC would still be wise.

Monday will still be a warm day. The thermal structure may be a
degree or so cooler. By Tuesday, thicknesses will be lower and
insolation less, supporting highs around 80 degrees east of the
Blue Ridge. Since dewpoints will be the same, low temperature
forecasts will be rather constant through the period.


First part of the long term period will be determined by
Hurricane Maria. Guidance suggests that Maria will be hovering
just off of the North Carolina Outer Banks Wednesday into
Thursday. This could somewhat increase winds over the
southeastern portion of our CWA, but not expecting them to be
particularly strong, maybe some gusts around 30 mph range in
southern MD and over parts of the bay, Some showers from outer
rain bands possible as well. The rest of our CWA can expect less
impacts as we will remain in a warm air mass.

Upper trough and its associated cold front should push the hurricane
eastward away from the coast Thursday into Friday. This cold front
will put an end to our above normal temperatures for late September
and a more seasonable air mass will arrive behind it sometime
Thursday or Friday. The fropa doesn`t look that moist, so expecting
just some showers with it.

Another -weaker- cold front approaches on Saturday and high pressure
builds behind it into Sunday.


VFR flight conditions will prevail through most of the valid
TAF period. Early morning fog possible Mon and Tue, clipping
MRB and CHO. Have kept that risk in the TAF at MVFR. Will also
need to watch for low clouds sneaking inland Monday night-
Tuesday morning.

Clouds will be more prevalent Tuesday. Flight restrictions
possible, depending on what advects inland that early morning.

Some sub-VFR conditions possible Wednesday into Thursday with
maybe some showers around. VFR conditions expected later on
Thursday and into Friday with high pressure building in


Winds will be light (at or below 10 kt) through Monday. Winds
will generally be from the northeast, with some variation
between north and east. Winds will increase Monday night and
Tuesday as Maria nears. At this time Small Craft conditions
possible in the mid Bay Tuesday, and expected Wednesday into
Thursday with Hurricane Maria nearby. That could change
contingent on the path/strength of Maria. Consult NHC products
for updates.


Straits Point fell just below minor stage with the latest high
tide. As the Monday morning high tide is astronomically lower
this was dropped.

It`s possible that tides will be peaking at the threshold
between caution and minor flood for a couple of cycles.
Eventually, water levels should be rising as Maria nears, but
there is ample spread in the guidance by that point.




PREVIOUS...HTS/IMR is the U.S. government's official web portal to all federal, state and local government web resources and services.