Area Forecast Discussion
Issued by NWS Blacksburg, VA-- Highlight Changed Discussion --
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FXUS61 KRNK 171711
Area Forecast Discussion
National Weather Service Blacksburg VA
1211 PM EST Fri Feb 17 2017
A warm front will move northeast through the area this morning,
winds becoming southwesterly with moderating temperatures.
High pressure centered over the southeastern states will remain
in control through tonight. A weather disturbance over Texas
will move northeast toward the region Saturday with a threat for
rain showers Saturday night and early Sunday. Temperatures will
trend 10 to 20 degrees above normal for the next 7 days.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 947 AM EST Friday...Early-AM cloud clover has shifted
eastward with abundant sunshine. A light southwesterly wind at
the surface increases as you go at elevation but all in all, a
very nice day on tap. As current temperatures are running some
3-6 degrees warmer, I tried to tweak these upward and raised
high temperatures up by a couple degrees. This puts many areas
into the upper 50s with mid/upper 60s across the VA/NC foothills
and Piedmont areas.
Previous near-term discussion issued at 430 AM follows...
A weak upper level disturbance will zip through the area early
this morning. Some of the meso models try to produce some trace
amount of precip over southside VA vcnty of South Boston and
Charlotte Court House. Most of this should be Virga, but if it
does reach the ground, it would be in the form of a brief
flurry. These same models rapidly clear-out all of the
cloudiness by 9AM with widespread sunshine for the later half of
the morning and the entire afternoon.
Warm air advection pattern begins today with southwest winds
promoting increasing warmth. 85H temperatures take a 5 to 10
degree jump during the day with readings starting off near zero
deg C at daybreak and reaching 7 to 10 deg C by sunset. As such,
after a cool start with temperatures near freezing, will rapidly
warm into the 50s/60s for the afternoon.
Surface High pressure is centered over the southeast states, and
will become semi-permanent for the next 5 to 7 days. Clockwise
flow around the high will maintain a warm southwest wind flow
aloft. Only fly in the ointment will be an upper level
southern stream trough of low pressure that will move out of
Texas tonight, crossing the area this weekend, but this will
have little impact to the forecast warm temperature anomaly.
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
As of 400 AM EST Friday...
A southern stream low pressure system will track out of the southern
plains to the Tennessee Valley Saturday. This system will then move
over the southern Appalachains Saturday night and off the southeast
coast Sunday. Light rain will enter extreme southwestern Virginia
Saturday afternoon, then spreads east across the forecast area
Saturday night exiting Sunday morning. The best chance for a wetting
rain will come after midnight Sunday for the mountains with the
deformation zone sliding across the area. Rainfall amounts may range
from a quarter /0.25/ of an inch over southeastern West Virginia to
a tenth or two /0.10-0.20/ across southwestern Virginia mountains.
Less than a tenth of an inch of rainfall is expected east of the
Blue Ridge as the wind veers to the west Saturday night into Sunday
morning. Temperatures will remain above freezing through the event
for all precipitation to fall as rain. High pressure and drier
weather builds in behind the low into early next week.
Being ahead of this southern stream low, Saturday temperatures will
be 15F-20F warmer than normal with 60s across the mountains to near
70F east. Some cool air will filter in behind the low Sunday, but
temperatures will remain 10F-15F warmer than normal. Temperatures
Monday will continue to stay warm with widespread 60s west to lower
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
As of 310 PM EST Thursday...
The upper ridge over the eastern US will flatten as the pattern
transitions to more of a zonal flow, with a closed low slowly weakening
as it moves eastward along the Gulf coast. This will continue our fair
weather and warm conditions into the start of next week. However, high
pressure will wedge in behind a backdoor cold front late Monday into
Monday night. While a sprinkle may accompany the front Monday night,
the main effect will be for a bit of a cool down on Tuesday though
readings will still be above normal. Differences in guidance bring
increasing uncertainty to the forecast heading into midweek as the
upper trof flattens. The most likely scenario will be for an increasing
chance of scattered showers Tuesday night and Wednesday thanks to some
short wave energy and an approaching frontal boundary. However, overall
dynamic support appears limited with little isentropic lift so overall
extent and magnitude of any precipitation will not be great. The track
of the closed low over the Gulf appears to be trending further south,
creating a drier solution for the Appalachians and central mid Atlantic
region with just a slight chance of a shower.
.AVIATION /17Z FRIDAY THROUGH TUESDAY/...
As of 1210 PM EST Friday...
VFR through the TAF period. SKC conditions to prevail until
around 12z Saturday, with a general lowering/thickening of
predominantly mid clouds thereafter.
Southwest winds rest of today around 8-12 kts with gusts to 22
kts. Winds then slacken this evening to 5-8 kts, however as low-
level jet of 35 kts approaches tonight, potential for instances
of low- level wind shear. Winds 4-8 kts from the south
Extended Aviation Discussion...
Next potential for sub-VFR conditions is late Saturday into
Sunday as a disturbance moves into the area from the Deep South.
Warmer temperatures will accompany this system, so any
precipitation should be in the form of rain showers. Lower
ceilings associated with these showers may linger into Sunday
before clearing and return to VFR Sunday night through Tuesday.