Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 160218 AAA

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
918 PM EST Fri Dec 15 2017

High pressure will build south of the area through early Sunday.
A weak backdoor cold front will stall over the area Sunday then
lift north as a warm front on Monday. A surface trof will move
across the area Tuesday. Weak high pressure builds over the area
during the second half of next week.



Temperatures have dropped significantly this evening where skies
are clear and winds are light. Stratocumulus are seen over
eastern WV and western MD where winds have picked up from the
west and are gusting over 25 mph. Temperatures in those areas
have jumped dramatically from the low 20s to near freezing in a
short period of time as seen at Martinsburg. Temperatures will
bottom out in the upper teens east of the mtns in the next few
hrs but will likely rise overnight as winds strengthen and
mixing increases. There could be a few snow showers over the
mtns overnight as upslope flow increases potentially dropping as
much as half inch of snow. Any freezing fog this evening is
expected to dissipate by midnight as winds strengthen and mixing
increases. Overall, cold and breezy overnight.


High pressure will remain to our south for Saturday and Saturday
night. A southwest flow around the high will usher in somewhat
milder conditions Saturday afternoon after a chilly start. Max
temps will be in the 40s for most areas.

High pressure will move offshore Sunday and a southerly flow
will usher in more moisture and somewhat milder conditions. Max
temps will be in the 40s for most areas with lower 50s in
central Virginia. An upper-level disturbance will pass through
late Sunday and Sunday night. A few showers are possible...but
forcing from this system will be weak so any precipitation that
does fall will be light.


Mild conditions expected during the long term period with dry
conditions on Monday as we sit between two boundaries and
southerly flow settles over our region. Some showers could
develop over higher elevations later on Monday and into Tuesday,
but still expecting mainly dry conditions over our CWA.

A cold front approaches Tuesday night increasing PoPs over our
area, but QPFs are not impressive. High pressure settles in
behind the front Wednesday into Friday with winds become
northwesterly... then becoming southwesterly Thursday into
Friday as high pressure moves offshore.

Temperatures will be above normal in general with highs reaching
the 50s and 60s in most locations, except on Wednesday. Low
temperatures will be in the 30s and 40s, but colder on Wednesday


VFR conditions are expected tonight through Sunday morning. A
few showers are possible later Sunday and Sunday night along
with MVFR conditions...but confidence in precipitation is low at
this time.

VFR conditions expected Monday into Wednesday. Maybe
sub-VFR conditions on Tuesday night as showers could move
through the terminals. Gusty winds expected on Wednesday, up
to 20 kt.


Low pressure will move out to sea tonight. A Small Craft
Advisory is in effect for the Maryland Chesapeake Bay south of
Drum Point and the lower Tidal Potomac River...closer to the
gradient. High pressure will build to the south for tonight
through Saturday...but a tightening gradient will result in SCA
conditions. The gradient will subside Saturday night and
Sunday. A weak disturbance will pass through Sunday night.

Winds are expected to stay below small craft advisory
threshold Monday into Tuesday. Winds could increase Tuesday
night into Wednesday behind a front, requiring a small craft
advisory over the waters.


MARINE...Small Craft Advisory from midnight tonight to 7 PM EST
     Saturday for ANZ530>534-537-539>541-543.
     Small Craft Advisory from noon to 7 PM EST Saturday for ANZ535-


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