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Area forecast discussion...updated
National Weather Service Baltimore Maryland/Washington District of Columbia
256 PM EDT Sat Oct 21 2017

Synopsis...high pressure will move east into the western Atlantic
through Monday. Low pressure and its attendant cold front will
sweep through the area Tuesday. Troughing will remain overhead
for much of the second half of the week.


Near term /until 6 am Sunday morning/...

High pressure will remain in control surface and aloft. Quite a
bit more of high clouds expected tonight than yesterday. Temps a
bit warmer tonight due to more clouds.


Short term /6 am Sunday morning through Monday night/...

Quiet wx sun-Sun night under high pressure. Clouds begin to
increase Mon with showers expected by midday on the west and
spreading east through the afternoon. Heavy showers with
possible T-storms and gusty winds Mon night as cdfnt enters the


Long term /Tuesday through Saturday/...

Strong front moving through Tuesday is main story in long term. This
system looks potent with potential for a period of heavy, wind swept
rain ahead of and along the primary cold front. Strong southerly
fetch ahead of it should bring copious moisture north, but speed
should limit flood concern. Gusty winds possible with very strong
low level jet, but most likely any winds of a threatening nature
will be limited to the cold frontal passage itself - low topped
squalls possibly embedded within larger rain band is the concern.
Timing remains a bit uncertain but right now, its favoring the am.

Breezy and much cooler behind the front, with the coolest days
likely Wednesday-Thursday. Some freeze issues are possible, though
this cold shot looks very transitory and if it doesn't align with a
good radiational night, it just might be chilly versus freezing.
Upper trough plus wraparound moisture might result in a few showers
Wednesday as well, especially in the mountains. If its cold enough
in the higher terrain, these could well be snow showers.

Drying out and moderating Friday with high pressure building in.


Aviation /19z Saturday through Thursday/...

Quiet wx through Sun night. Clouds increase Mon with showers
expected Mon night. Low level wind shear is also possible.

Primary concern with tafs in long term will be the strong front
moving through Tuesday. Potential for heavy rain and IFR cigs/vis,
along with low level wind shear and gusty winds - perhaps isolated 30-40 knot gusts.
Timing still a bit uncertain but right now favoring the am.

After that, northwest wind may be gusty, but becoming VFR overall for the
rest of the week. A few showers possible, mainly Wednesday, but
cig/vis reductions should be minimal.


Marine...winds will begin to strengthen Mon in srly flow. Small Craft Advisory
conditions likely by late Mon and solid Small Craft Advisory conditions expected

Gales possible Tuesday as strong cold front barrells through. Small Craft Advisory
possible Wednesday as the system moves away and high pressure builds


Lwx watches/warnings/advisories...
District of Columbia...none.



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