Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KRNK 111701
Area Forecast Discussion
National Weather Service Blacksburg VA
1201 PM EST Wed Jan 11 2017
Low pressure will move from the Great Lakes to the northeast
U.S. today, dragging a cold front through the region. This front
will stall near the Virginia/North Carolina border tonight as
high pressure aloft builds across the southeast U.S. This front
will return north as a warm front tonight moving back into the
northeast U.S. Another front will approach the region from the
north by Thursday night, then stall across northern West
Virginia into northern Virginia Friday.
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --AS of 1100 AM EST Wednesday...
Made some minor adjustments in pops and weather to match up
better with WSR-88d Trends. Adjusted temperatures for this
As of 915 AM EST Wednesday...
Adjusted pops with latest radar images and their trends for
this morning. Utilized a blend of HRRR, HiResW-arw-east and
continuity for pops late morning into this afternoon. Added
areas of fog to the isc grids. Modified temperatures with sfc
obs and leaned late morning temperatures towards GLAMP which
captured the cooler pockets better. Temperatures will continue
to increase today as 850mb temperatures are already +5C or
better and will climb to around +8 to 10C by Thursday. High
temperatures this afternoon will range from around 40 in the
mountains to the lower 50s in the Piedmont. More changes
As of 430 AM EST Wednesday...
Going from what has been a true winter pattern into one more
typical of summer as a 590dm upper ridge builds across the
southeast U.S. and a series of fronts moves into or near the
region and then stall, leaving a baroclinic zone in or near the
area for most of the week. Hence, a cloudy, wet pattern.
Temperatures will trend above normal fairly quickly after today
as the region moves into the warm sector. Looking ahead, there
is really no sign of any below freezing temperatures of
significant now until the 24th of January! I guess you could
cause this the January Thaw after the bitter cold and snow of
this past weekend.
Low pressure associated with a northern stream trough will move
through the Great Lakes today fairly quickly and drag a cold
front down into TN and NC. As the low moves into eastern Canada
and an upper ridge builds across the southeast states, the front
will stall just south of the NC/VA border, then return fairly
quickly as a warm front tonight. Rain associated with the front
this morning will drift south and especially southwest toward
the TN/NC/VA borders, then return north during the
afternoon/evening back across the northern parts of the CWA. The
warm frontal associated rainfall will then drift north into
northern VA/WV overnight. This will leave the CWA with likely to
categorical pops at times today, trending toward pops decreasing
toward slight chance tonight from south to north. After midnight
with deep low-level moisture in place, areas of drizzle may
develop from the Shenandoah Valley southwest into the New River
Temperatures have risen above freezing throughout the CWA at
this hour, so any threat of freezing precipitation has ended.
Temperatures will continue to increase today as 850mb temps are
already +5C or better and will to increase toward +10C as the
week continues. However, snow pack currently across most of the
CWA as a result of this last weekend`s snow storm will impact
warming. Have continued to undercut MOS guidance by several
degrees, especially Piedmont areas where the snowpack is deeper,
until the snow pack is gone.
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.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 400 AM EST Wednesday...
The region will be in the southern stream of a split flow regime by
Thursday, with a large cutoff low over the southwest and some flat
ridging over the southeast. This will keep us in a mild and moist
pattern with cold air bottled up well to our north.
With a weak baroclinic zone just off to our west there may be a few
sprinkles west of the Blue Ridge but little in the way of significant
precipitation elsewhere on Thursday. High pressure moving into the
Great Lakes region will push the baroclinic zone closer to us Thursday
night with increasing precipitation chances west of the Ridge. On
Friday, the high will wedge strongly down the east side of the
Appalachians and push the baroclinic zone through the region as a
backdoor cold front with a good chance of showers across the entire
region later Friday into Friday night. Temperatures in the wedge look
to support the possibility of some freezing rain across the Alleghany
Highlands and down the higher elevations of Blue Ridge for a bit late
Friday night. The wedge looks to hold firm into Saturday morning when a
wave of low pressure moves out of the Mississippi valley and brings
another surge of showers to locations west of the Ridge.
Temperatures will be well above normal through the end of the week with
highs in the low to mid 60s east of the Blue Ridge and mid 50s to
around 60 degrees west. However, the developing wedge will bring much
cooler conditions back to the area with highs Saturday in the low to
mid 40s with warmer readings along the western and southern periphery
of the wedge.
.LONG TERM /SUNDAY THROUGH TUESDAY/...
.AS OF 400 AM EST Wednesday...
Behind the wave of low pressure, the wedge will reestablish itself over
the region through the first part of next week, then drift slowly to
the east, eventually pushing a warm front through the area on Tuesday.
The end result will be a persistent chance of showers accompanied by a
gradual warming trend to above normal temperatures.
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --As of 1200 PM EST Wednesday...
Quickly changing conditions with low clouds, rain and fog will
hinder aviation operations into Thursday morning. SCT to BKN
MVFR clouds will continue this afternoon into tonight. Pockets
of IFR and LIFR are possible in low clouds, fog and rain. A warm
front with associated overrunning precipitation will lift north
across the region this afternoon into tonight. As the front
moves north of the region a moist air mass will be left in place
over some snow covered ground this evening into Thursday
morning. Expect widespread fog and drizzle to develop as a
result with attendant IFR-LIFR conditions at most TAF sites
throughout the remainder of the night. Look for ceilings and
visibilities to rise Thursday morning.
Southerly winds at 5-7 kts this afternoon will trend toward calm or
less than 5kts overnight. Southwest winds at 5 to 15 kts will
prevail Thursday. Winds will be gusty along the ridges Thursday
morning into Thursday afternoon.
Medium confidence in ceilings, visibilities and winds through the
TAF valid period.
Extended Aviation Discussion...
Little to no improvement is expected through the period. A
backdoor frontal system will work its way south into the region
Friday into Saturday, maintaining the threat for additional sub-
VFR in low cigs along with light rain and/or drizzle. Unsettled
weather will continue into Sunday with some slow improvement in
conditions as high pressure wedges in from the north, but
likely still MVFR cigs at best.
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