Scientific Forecaster Discussion
fxus61 klwx 220042
Area forecast discussion
National Weather Service Baltimore Maryland/Washington District of Columbia
842 PM EDT Sat Oct 21 2017
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 resudes across the northeast and mid Atlantic
section of the Continental U.S.. in spite of this, ample upper level
moisture has drifed atop the ridge, resulting in a deck of
cirrus. Skies became mostly cloudy if not cloudy just prior to
sunset, and remains so at this time. Infrared satellite and rap BUFKIT
overview suggest there will be little change until the pre-dawn
hours. Have made these adjustments in the sky grids. Will be
assessing if low temperatures need to be bumped up slightly
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 /01z Sunday through Thursday/...
VFR conditions through Sunday evening. A southerly flow will
strengthen ahead of a cold front overnight Sunday and Monday.
Moisture streaming into the area will cause more clouds along with
the possibility for subvfr cigs. Patchy fog is also possible
overnight. The cold front will pass through overnight Monday
into early Tuesday. Low level wind shear is possible during this time.
A soaking rain is also expected with the frontal passage and there
is a potential for heavy rain and IFR cigs/vis, along with gusty
winds - perhaps isolated 30-40 knot gusts. Timing still a bit
uncertain but right now favoring between 06z-12z early Tuesday.
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.
winds will begin to strengthen Mon in srly flow. Small Craft Advisory conditions
likely by late Mon and solid Small Craft Advisory conditions expected Tue.
Gales possible Tuesday as strong cold front barrells through. Small Craft Advisory
possible Wednesday as the system moves away and high pressure builds
District of Columbia...none.