Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 131302

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
902 AM EDT Wed Sep 13 2017

The remnants of Irma will move across the Ohio Valley today and
into Pennsylvania Thursday. High pressure will return to our
region during the weekend.



Rain showers over northeast MD will continue to track
northeast, but visible satellite shows extensive cloud cover
remains across all except southern VA, so it won`t be until the
afternoon that we encounter a few peeks of sunshine. High
temperatures near 80.

This evening will be predominantly dry with weak high pressure
in control ahead of the last stage of the remnants of Irma.
Models are indicating increasing clouds and chances of showers
after midnight in the Potomac Highlands. Chances will proceed
eastward to the I-81 corridor and the Shenandoah Valley by
daybreak Thursday. Rain amounts would be generally between one
tenth to one quarter of an inch and would be mainly in the
northern Potomac Highlands, along the Mason-Dixon region.


The chance for rain showers persists from west to east Thursday
with a few thunderstorms along the Mason-Dixon region from
around central Maryland east to the northern Chesapeake Bay and
south to around the I-66 corridor. Thunderstorms should be
isolated Thursday afternoon due to daytime heating underneath a
remnant low of Irma. Once evening approaches, any thunderstorms
will lose their punch. High temperatures Thursday will be lower
80s mainly east of I-95, near 80 along and just east of the
Blue Ridge, and mid to upper 70s west.

The chance for lingering rain showers exist Thursday evening before
a quiet period Thursday overnight arrives as the low slides to
the east. Low temps Thursday night will be cooler than Wednesday

Models are indicating that a small piece of energy could wrap around
the departing remnant low Friday and approach us from the north
before departing to the east as well. For this reason, as well as
our high temperatures reaching around 80 once again, we will allow
for a chance of a few rain showers in parts of the region.

Dry conditions should arrive once again Friday night as this final
piece of energy slides to the south and east. Lows will be in
mid 60s.



Extended forecast hinges on the fate of Jose. There is limited
skill at track/intensity forecasts at this timeframe, which is
only magnified by lack of run-to-run forecast consistency
amongst model guidance. Latest official NHC forecast calls for
this cyclone to loop toward coast but stay offshore through
Sunday, which is what the local extended forecast will be based
upon. That still wouldn`t preclude occasional 20-30% PoPs this
weekend into early next week due to onshore flow, vort lobes
and/or an approaching cold front.


IFR at all TAF sites expected to continue through late morning.

VFR expected at all terminals this afternoon into Thursday

MVFR or brief IFR conditions possible at all sites except CHO
Thursday afternoon due to isolated thunderstorms that could
develop due to daytime heating under the remnant low of Irma.
VFR conditions at all terminals Thursday night. Winds shifting
northwest 5 to 10 knots Thursday, becoming light and variable
Thursday night.

VFR conditions for the most part Friday at all terminals.VFR
conditions Friday night. Winds northwest around 5 knots Friday
into Friday night.


No marine hazards expected today through Friday night.

Winds should be mainly 10 kt or less this weekend due to a ridge
of high pressure located near the waters.




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