Area Forecast Discussion
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FXUS61 KLWX 052001
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
301 PM EST Mon Dec 5 2016
High pressure will briefly build over the region today into
tonight. Coastal low pressure will impact the area Tuesday into
Tuesday night before high pressure briefly returns again for
Wednesday. A potent cold front will pass through Thursday and
arctic high pressure will build overhead during the weekend.
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Mostly clear conditions will continue this afternoon and into
tonight as high pressure approaches the region from the Ohio Valley.
Light winds and clear skies will allow temperatures to drop into the
30s overnight ahead of the next low pressure system.
High pressure will move over New England and filter down into the Mid-
Atlantic by Tuesday morning. A negatively tilted shortwave trough
will move into the gulf coast states overnight and warm
airadvection will increase across the Mid-Atlantic overnight. Mid-
highlevel clouds will increase from the Shenandoah Valley to
northeastMD overnight and into Tuesday morning. As the surface low
moves intothe TN Valley overnight/early Tuesday morning,
precipitation willbegin to move into the VA highlands between
after midnight tonight.As stated above temperatures will drop into
the 30s overnight andnear freezing temperatures are expected at
elevations above 2k feet.Due to the warm air advection aloft a
warm layer will result inmixed precipitation at these higher
elevations. A combination ofsnow and sleet are expected on the
onset of precipitation. The warmlayer will continue and with
temperatures below freezing...fzra isexpected through Tuesday at
higher elevations. A winter weatheradvisory was issued for the
Allegheny Front and VA Highlands.Elsewhere surface temperatures
will be above freezing and the main p-type will be rain however a
brief period of sleet is possible at theon-set. &&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Precipitation will spread northward into Tuesday morning and
pockets of freezing rain are possible further east of the
advisory mainly at higher elevations along the Blue Ridge Mtns
and Catoctin Mtns. An extension to the winter weather advisory
may be needed. Rain will move northward and into the DC metro and
eventually to the Baltimore metro by late morning.
Most of the forcing will be further south as low pressure moves
off the Carolina coastline by Tuesday afternoon/evening. Rain
amounts of around a half inch are expected through Tuesday
however amts up to 0.75 are possible across Central VA/S MD.
The shortwave trough will move across the region Tuesday
night. Temperatures will likely max out in the 30s and around the
low 40s across the I-95 corridor Tuesday afternoon/evening. Temps
will slowly rise into the evening however winds will become NW by
Wed morning and cool dry air will move into the region.
Sunny conditions expected Wednesday with temperatures reaching the
40s and 50s along I-95. A cold front will approach the region
.LONG TERM /THURSDAY THROUGH MONDAY/...
A storm system will approach from the west Thursday and Thursday
night. A chance of rain or snow showers exist across the region each
period. Precipitation should be light in intensity with chilly
High pressure is expected to build in from the west Friday through
Saturday night. This high could bring the chilliest air so far this
season. Some upslope snow showers could also occur in the Potomac
The high will move offshore of the East Coast Sunday ahead of the
next approaching trough of low pressure Sunday night into Monday.
This next storm system could bring a chance of wintry precipitation
at the onset Sunday night, change over to rain, before ending as a
little snow sometime on Monday. The confidence in the timing and
precipitation type is low. The 12z GFS model is moving this storm
system eastward much faster than the 00z European model. We will
have to see how the 12z European model handles the storm.
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
VFR conditions are expected through this evening. Rain is expected
to move into the terminals Tuesday morning. Cigs will lower and
MVFR conditions are expected through Tuesday morning. A brief
period of PL is possible mainly at CHO/MRB/IAD when rain moves
into the region. Cigs will become IFR by Tuesday afternoon. Rain
will move out of the region Tuesday evening however cigs will
likely stay MVFR/IFR through Tuesday evening. VFR conditions
Mvfr to ifr conditions possible in any rain or snow showers Thursday
and Thursday night. Winds variable 5 to 10 knots Thursday becoming
northwest and increasing 10 to 15 knots gusts 20 knots Thursday
NW Winds will continue this afternoon as high pressure approaches
from the west. A Small Craft Advisory is in effect for the waters
during this time...but it will be marginal with gusts around 15 to
20 knots. High pressure will build overhead tonight before coastal
low pressure impacts the waters Tuesday. A Small Craft Advisory is
in effect for portions of the waters Tuesday afternoon.
No marine hazards expected Thursday. Small craft advisories possible
Thursday night. Winds becoming northwest 15 to 20 knots gusts 20 to
25 knots Thursday night.&&
MD...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
VA...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
WV...Winter Weather Advisory from 2 AM to 7 PM EST Tuesday for
MARINE...Small Craft Advisory until 5 PM EST this afternoon for
Small Craft Advisory from noon to 6 PM EST Tuesday for