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NWS Area Weather Forecast Discussion
County Warning Area [CWA]: RNK
Regional NWS Weather Office: Blacksburg, VA

000
FXUS61 KRNK 252340
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
740 PM EDT Thu May 25 2017

.SYNOPSIS...
A broad area of low pressure extended from Ohio to the Delmarva
Peninsula. High pressure will make a brief visit to our region on
Friday. Wet weather returns to the area over the weekend as a
frontal boundary stalls overhead, and a series of disturbances moves
along it.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 730 PM EDT Thursday...

Upper low and a series of short waves will continue to bring
showers across the area overnight. Eventually, downsloping
northwest winds will limit rain chances east of the Blue Ridge
after midnight. Rainfall amounts overnight should not contribute
much to the already wet ground.


As of 230 PM EDT Thursday...

An upper low was positioned near the Mason-Dixon Line. Flow on the
backside of this low is progged to increase to around 40kts this
evening, and continue as such through the overnight hours. A Wind
Advisory will remain in effect for areas near and west of the crest
of Blue Ridge. While official wind advisory wind level speeds
and gusts are not anticipated, the impact of increasing gusty
winds and saturated soils will allow for trees to be blown down
more easily.

Central and eastern sections of the region have had a decent amount
of sunshine this afternoon. We expect showers and storms to develop
this afternoon and continue into the evening hours, supported by
steep lapse rates aloft associated with the cold pool of the upper
low. The relatively low freezing level will allow for just about
any thunderstorm to have the potential for small hail, as well
as, the stronger rain showers.

By late this evening, flow across the entire region will be from the
northwest, and subsidence will begin to win across eastern parts of
the area. Look for precipitation to end, and for there to be a trend
in clearing skies after midnight. In the west, the northwest flow
will help maintain upslope clouds and scattered rain showers. These
showers will continue through the night and into the morning hours
on Friday. Coverage will decrease during the day Friday as low level
winds start to slow and back. Clouds will also be on the decrease.

Temperatures will continue to be on the cool side overnight. Expect
low temperatures tonight across the mountains to range from the
upper 40s to lower 50s. Across the Piedmont, low to mid 50s are
forecast.

On Friday, sunshine in the east, and sunshine in the west by the
afternoon, will help yield high temperatures close to ten degrees
warmer than those realized today. Expect the low to mid 70s across
the mountains with upper 70s to around 80 across the Piedmont.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 1100 AM EDT Thursday...

Friday night through the weekend, an upper level shortwave ridge
will be positioned across the Tennessee Valley. A closed upper low
will slowly progress from south central Canada towards the Great
Lakes region. During this period, anticipate central U.S. shortwave
troughs to be funneled eastward between the flow of these two
features into the Ohio Valley, all the while the Tennessee ridge
slowly erodes. This will allow for increasing coverage of shower
activity by the end of the weekend, especially by Sunday into Sunday
night with the approach of a cold front.

Temperatures Friday into Sunday will be near normal, with
temperatures about five degrees above normal by Sunday.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 1030 AM EDT Thursday...

During the period of Monday through Wednesday, an upper level low
will gradually progress eastward through the Great Lakes region and
into southeast Canada. A couple of associated cold fronts are
expected to spiral ahead of this system and progress into the
eastern part of the U.S.  Model timing of these front places one
moving through on Monday, and then the second on Wednesday, with the
first of the two the most potent for our region. This scenario
offers scattered showers in the forecast both of these days, with
some isolated thunderstorms more probable on Monday as compared to
Wednesday. Tuesday may not be completely precipitation free,
but very limited on cover and due more to differential heating.

On Thursday, guidance differs on the extent precipitation will be
possible for the area, and much will be determined based upon how
far the front on Wednesday exits the region, and to what extent a
southern stream shortwave trough rides northeast along this front
into, or near the area. Our forecast will reflect a model blend
consensus of solutions, with better chances of showers on Thursday
than not.

Temperatures during this portion of the forecast will be a little
over five degrees above normal on Monday, but trend to near normal
conditions on Thursday.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 140 PM EDT Thursday...

Upper low and a series of short waves will continue to bring
showers across the area overnight. Eventually, downsloping
northwest winds will limit rain chances east of the Blue Ridge.
A broad area of IFR/MVFR cloud cover will remain over the
mountains tonight with improving conditions east of the Blue
Ridge likely to occur by midnight. Visibilities will mainly be
VFR, but pockets of MVFR visibilities are possible across
western slopes.

Wind gusts across the higher elevations will be in the
neighborhood of 25 to 35 kts through Friday afternoon. These
winds will mix down to the lower levels by mid morning.

Extended Aviation Discussion...

We will transition back into a wet pattern over the weekend as a
frontal boundary enters and stalls over the area. A series of
disturbances will bring showers and storms to the area.
Anticipate at least some pockets of sub-VFR conditions.

The coverage of showers and storms decrease early next week, but
remain at least scattered in coverage.

&&

.HYDROLOGY...
As of 100 PM EDT Thursday...

Small streams and creeks have been receding and most are below flood
stage. We are in a river flooding scenario for portions of the
Roanoke and Dan River basins. The New River and Greenbrier river are
expect to stay below flood stage.

The upper level system moving in from the west will bring scattered
to numerous showers and possible thunderstorms. Overall rainfall
amounts on average will be under a quarter to half inch, in this
scenario. Will have to watch for any training or heavier downpours,
as it will not take much to cause flooding again given the saturated
grounds and swollen creeks and rivers.

Currently, we are not expecting enough for a flood/flash flood watch
and activity should diminish/weaken after sunset.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Wind Advisory until noon EDT Friday for VAZ007-009>020-022>024-
     032>035.
NC...Wind Advisory until noon EDT Friday for NCZ001-002-018.
WV...Wind Advisory until noon EDT Friday for WVZ042>044-507-508.

&&

$$
SYNOPSIS...DS
NEAR TERM...DS
SHORT TERM...DS
LONG TERM...DS
AVIATION...DS/RCS
HYDROLOGY...WP

Forecast Discussion from: NOAA-NWS Script developed by: El Dorado Weather