High Wind and Strong Wind in North Carolina, September 11 to 12, 2017

Area Forecast Discussion
National Weather Service Blacksburg VA
331 PM EDT Mon Sep 11 2017

.SYNOPSIS...
Irma tracks northward into southwest Georgia tonight while
continuing to weaken. Its remnants will head northwest into the
Tennessee Valley, and merge with an upper level disturbance on
Tuesday, before heading eastward across our region later in the
week.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 230 PM EDT Monday...

Shield of rain remains a little faster than most guidance with Irma
moving a bit quicker this afternoon toward southwest Georgia.
Expect this shield to overspread the western zones by this
evening as lift over the cool pool increases while being slower
out east where the wedge/dry air is deeper. Latest guidance even
showing some decrease in coverage after the initial onset early
this evening prior to tropical type PWATs advecting in, including
more banding nature from southeast to northwest overnight. This
along with deepening easterly flow again looks to pivot the
heaviest rainfall into the North Carolina mountains where models
differ from an inch or so off the GFS to the very wet Nam/NCAR
ensembles that have a swath of 2-4 inches along the southern
Blue Ridge. For now will lean on the high side while blending in
the ECMWF which has shown less QPF overall. However given
dryness of late and rather high flash flood guidance values,
will hold off on any watches as expecting higher rate rainfall
including elevated convection to remain closer to the coastal
front through early Tuesday. Otherwise continued slow northward
progression of likely to categorical pops overnight with
heaviest rain along/east of the mountains, and less over the
northwest where likely to be more in an easterly flow
downsloping shadow.

Winds remain a bigger issue overnight as the current pressure
gradient lingers and then increases as stronger winds aloft to the
northeast of Irma swing across after dark into the early morning
hours of Tuesday. However latest guidance a bit weaker with the 850
mb jet aloft, while having the stronger winds across the far
south and west at this point. Had toyed with expanding the wind
advisory across Giles and Floyd counties for the higher
elevations given forecast winds off the Nam earlier, and now for
consistency will go ahead and include all of the New River
Valley in the wind headlines, mainly for impact. Otherwise
little change to going headlines as appears that other than for
the western mountains will be more impact based at this point
for wet soils and toppling trees. Given such a chilly start late
today, bumped down lows into the 50s most spots this evening as
rain arrives, before readings start to rise with the wedge
eroding a bit given the influx of tropical moisture overnight.

Irma heads farther to the west Tuesday with a residual warm front
lifting north toward southern sections by late in the day. Best
expanse of upward motion with the main feeder band to either lift
north or split by midday leaving a more scattered nature to showers
espcly north and east in the afternoon. Guidance still showing some
weak instability working in from the southeast later in the day but
appears that this wont coincide with best shear aloft, and deeper
banding to aid any isolated spin up potential for now. Still looks
like another half to one inch of rain in spots pending where bands
set up with high pops tapering to chance or low likelys late in the
day. Kept highs on the low end of guidance given the lingering wedge
which supports 60s most spots, except around 70 far west as well as
southeast sections.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS of 300 PM EDT Monday...

By Tuesday night, the remnants of Tropical Storm Irma will be
stalled just east of Memphis, TN. Over the next 48 hours, the
system will shift eastward as a post-tropical system in response
to a building upper ridge over the western third of CONUS.
Tuesday evening, the last of what could be considered moisture
feeder bands from off the Atlantic, is progged to shift north of
our region. This will allow for a period of showers during the
evening that dissipate as the night progresses.

On Wednesday, the area will be in a bit of a lull between the
activity from the night before, and showers associated with the
advance eastward of Irma's remnants.  Isolated showers will be
possible in the northeast during the morning, and then again in the
southwest toward the late afternoon. Otherwise, most of the region
on Wednesday will not experience precipitation.

Wednesday night through Thursday night look for scattered showers
across the region, especially during the peak heating of the day
on Thursday as the aforementioned remnant low makes eastward
progress upstream along with the Ohio River basin.

While showers are forecast during this time period, Thursday
afternoon across the far northern and eastern sections of the
region, instability may be great enough to allow for some isolated
thunderstorms.

Low temperatures during this portion of the forecast will experience
limited changes, with mid to upper 50s common across the mountains
and upper 50s to lower 60s common across the Piedmont. High
temperatures will experience a slight cooling trend. On Wednesday
highs will range from around 70 to the mid 70s across the mountains
with upper 70s to around 80 across the Piedmont. On Thursday,
readings will average about two degrees cooler than those expected
Wednesday.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 PM EDT Monday...

On Friday, the back edge of the departing remnant low will still be
across at least eastern sections of the area. Anticipate additional
isolated or scattered showers, especially during the peak heating of
the day.  Model guidance differs as to how quickly the low exits by
Saturday, with some solutions keeping isolated showers over the area
Saturday as well, some with having an upper ridge taking hold
of our weather pattern and shunting any additional showers
eastward. Our forecast will follow persistence of the prior
forecast with a mention of isolated showers on Saturday.

Sunday into Monday there are notable differences in model solutions.
To some degree all are consistent with having Hurricane Jose at some
distance east off the mid-Atlantic coast. Also, there is
consistency in having a cold front approaching through the Great
Lakes/Ohio Valley region. Where the differences impact our
region are just how far off the coast the tropical system is,
and just how close the cold front is in comparison to both our
region and the tropical system. Our forecast will reflect a
consensus solution provided by Superblend of model guidance.
This output allows for some showers associated with the tropical
system to cross parts of the area on Sunday, with some
influence of the approaching cold front in the west on Monday.

Temperatures during this portion of the forecast will not deviate
much during the course of the four days. However, there will be a
small increase in temperatures from Friday into Saturday, and then a
small decrease Sunday into Monday. On average, low to upper 70s
across the mountains and upper 70s to lower 80s across the Piedmont
are expected for high temperatures. The mid to upper 50s across the
mountains and upper 50s to around 60 across the Piedmont are
expected for low temperatures.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
As of 1220 PM EDT Monday...

VFR conditions will gradually deteriorate from south to north
through the rest of the day with showers also progressing in
from the south through sunset. Arrival of lower MVFR cigs along
with the leading edge of the showers appears a bit faster than
previous as expecting rain to reach KDAN in the next few hours,
and a KBLF-KROA line by 20z/4pm unless dry air slows things up.
Showers should not arrive at KLWB/KLYH until around 22-00z/6-8
pm where will linger VFR conditions longer.

As Irma heads a bit faster across SW Georgia, shield of rain
should enhance across the region overnight with widespread MVFR
to IFR cigs including MVFR vsbys. Locally heavy rain with
embedded showers could also result in periods of IFR vsbys
espcly KDAN, while KLWB to KLYH may stay VFR longer into the
overnight.

East winds will also become gusty, sustained at 10-20 kts, with
gusts to 20-30kts, strongest along and south of a KBLF- KDAN
line, especially in the higher elevations. Airports such as MWK
and HLX to GEV and perhaps TNB may see gusts over 35 kts.

Expecting sub-VFR conditions to prevail for most of the time on
Tuesday as bands of showers to the east of a weakening Irma continue
to lift north through the region until late in the day. However
winds turning more southeast may allow improvement to VFR at
times outside of shower bands.

Extended Aviation Discussion...

Will likely see sub-VFR continue into Tuesday night under low
cigs but only isolated showers. Conditions should improve on
Wednesday with high pressure moving offshore and Irma stalling
across western Tennessee. However, scattered showers may return
later in the week as the remnants of Irma merge with an upper
level disturbance and head eastward. This may bring periodic
rounds of sub-VFR, mainly during the afternoon/evening hours of
Thursday and Friday.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Wind Advisory until 9 AM EDT Tuesday for VAZ007-009-010-012-
     015-016-032.
NC...Wind Advisory until 9 AM EDT Tuesday for NCZ001>004-018>020.
WV...Wind Advisory until 9 AM EDT Tuesday for WVZ042.

&&

SYNOPSIS...JH
NEAR TERM...JH/WP
SHORT TERM...DS
LONG TERM...DS
AVIATION...JH/PW/WP

Hazardous Weather Outlook...UPDATED
National Weather Service Blacksburg VA
309 PM EDT Mon Sep 11 2017

NCZ001-002-018-019-121915-
Ashe-Alleghany NC-Watauga-Wilkes-
309 PM EDT Mon Sep 11 2017

...WIND ADVISORY IN EFFECT UNTIL 9 AM EDT TUESDAY...

This Hazardous Weather Outlook is for northwest North Carolina.

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Wind Advisory.

In addition, bands of heavy rainfall will occur tonight which could
lead to localized flooding.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Wind Advisory.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

NCZ003-004-020-VAZ007-009>017-032-WVZ042-121915-
Surry-Stokes-Yadkin-Tazewell-Smyth-Bland-Giles-Wythe-Pulaski-
Montgomery-Grayson-Carroll-Floyd-Patrick-Mercer-
309 PM EDT Mon Sep 11 2017

...WIND ADVISORY IN EFFECT UNTIL 9 AM EDT TUESDAY...

This Hazardous Weather Outlook is for north central North Carolina,
northwest North Carolina, southwest Virginia and southeast West
Virginia.

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Wind Advisory.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Wind Advisory.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

NCZ005-006-VAZ018>020-022>024-033>035-043>047-058-059-WVZ043-044-507-
508-121915-
Rockingham-Caswell-Craig-Alleghany VA-Bath-Roanoke-Botetourt-
Rockbridge-Franklin-Bedford-Amherst-Henry-Pittsylvania-Campbell-
Appomattox-Buckingham-Halifax-Charlotte-Summers-Monroe-
Eastern Greenbrier-Western Greenbrier-
309 PM EDT Mon Sep 11 2017

This Hazardous Weather Outlook is for north central North Carolina,
central Virginia, south central Virginia, southwest Virginia, west
central Virginia and southeast West Virginia.

.DAY ONE...This afternoon and tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.