Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 271950

Area Forecast Discussion
National Weather Service Blacksburg VA
350 PM EDT Mon Mar 27 2017

Moist southerly flow will continue tonight into Tuesday, with
several rounds of showers and thunderstorms possible. Low
pressure in the Ohio Valley with a trailing cold front will lift
eastward tonight into Tuesday. This cold front will approach
us tonight and move east through the area Tuesday into Tuesday
night. Behind the front, drier air will arrive for midweek.


As of 350 PM EDT Monday...

Isolated to scattered convection developing ahead of the cold front
this afternoon in the warm and unstable air. This convection is
developing ahead of a lead shortwave moving ahead of an upper trough.
The convective outlook for Day 1 places the marginal risk of severe
weather to our west with the best instability and dynamics. Highres
models like the HRRR and ARW showed isolated convection developing
this afternoon into tonight, especially along the southern Blue
ridge. Models enhance lift and low level convergence across the
Blue Ridge into the foothills after midnight into the overnight
as the front approach the Appalachians. Low temperatures
tonight will range from the upper 40s in the mountains to near
60 degrees in the Piedmont.

A strong cold front will move across our region Tuesday into Tuesday
night. Scattered showers and Thunderstorms will develop ahead
and along this boundary. The SWODY2 has placed eastern portions
of CWA in a marginal risk for Tuesday. The timing of the
shortwave on Tuesday with a favorable area of forcing for ascent
moving across eastern portions during the afternoon during peak
heating. The shortwave should move offshore around 29/00Z. The
strongest storms could produce hail and locally damaging wind
gusts. High temperatures Tuesday will vary from the upper 50s
in the mountains to the mid 70s in the Piedmont.


As of 349 PM EDT Monday...

A cold front will move across the region Tuesday night with showers
exiting the piedmont during the evening. Some low level moisture may
squeeze out a few showers along western slopes overnight as the
theta-E boundary tracks south across the mountains. There is not
much cold air air behind this front, so any precipitation along
western slopes or across the mountains will be liquid and not frozen.

High pressure will move south out of Canada Wednesday, then wedge
down the east coast Wednesday night into Thursday. This wedge will
initial be dry and mostly clear Wednesday. Wednesday afternoon
temperatures will warm into the 60s west to 70s east. A strong area
of low pressure will track out of the Rockies Wednesday then across
the Midwest Thursday night. This system will throw warm moist air
over the wedge, increasing clouds and eventually the chance for
rain/drizzle. Saturation of the environment should not occur until
late Wednesday night into Thursday morning. Isentropic lift
increases during the day Thursday. With this in mind, we have
delayed the onset of stratiform rain/drizzle until late Thursday
morning and moreso along eastern slopes of the North Carolina High
Country and Grayson Highlands. The combination of rain falling into
a linger wedge will produce cool temperatures with highs in the 50s
areawide Thursday.


As of 349 PM EDT Monday...

A strong area on low pressure will track from the Midwest to the
south-central Appalachian mountains Thursday night into Friday. This
low will erode the wedge of cooler air that moved into the region
Wednesday. Dynamics from this low and with a retreating wedge
boundary, there is the possibility strong storms could develop across
the region Friday into Friday evening. However, timing is everything
with this event. Currently, models have dynamics and retreating
wedge environment occuring during the morning, which lowers the
threat for severe weather. If this event occurs later in the day,
then the threat for severe weather will increase. With an eroding
wedge, temperatures will increase Thursday night and into the day
Friday. Lows Thursday night will occur around midnight (upper 40s),
then rise into the low to mid 60s Friday afternoon.

This low pressure system and associated showers will exit the mid
Atlantic coast Friday night. Dry high pressure and near normal
temperatures will follow for the weekend.


As of 300 PM EDT Monday...

East to southeast flow will push moisture into our region this
afternoon into Tuesday. SCT to BKN MVFR clouds will continue
this afternoon into tonight. Ceiling will hold in many areas
with some breaks in the clouds from time to time. Showers
and thunderstorms will be isolated to scattered over the
mountains this afternoon into tonight. Better rain threat later
tonight ahead of the front, with cigs dropping to mvfr (ISOLD
IFR) towards 12z Tuesday in most areas.

Dominant wind flow into Tuesday will be from a southerly

Extended Aviation Discussion...

Front moves in the mountains after 12z Tuesday with best threat of
showers/some thunder and sub-VFR in the 09z-18z Tuesday time frame.
Cold front exits the Piedmont by 00z Wednesday with lingering sub-
VFR cigs in BLF/LWB with VFR in the EAst.

High pressure builds in from the north Wednesday into Thursday with
next storm system moving in the MS Valley. A threat for Sub-VFR cigs
appears likely as the high wedges southwest Wed night into Thursday
for most sites. Better chances of rain Thursday night into




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