River Flood Warning 17, NWS Morristown, TN

AREA FORECAST DISCUSSION
National Weather Service Morristown TN
109 AM EST Fri Feb 7 2020

.UPDATE...
FOR 06Z AVIATION.

&&

.DISCUSSION...
Updated to extend Winter Weather Advisory into the northern
Plateau and Lee County Virginia. Also, up winds for Friday to near
wind advisory levels.

Satellite shows another short-wave rotating across the lower
Mississippi valley into the Gulf coast states. A 135-140kt 300mb
jet associated with the trough will rotate across the Gulf coast
states toward the southern Appalachians overnight placing the area
under the favored left exit region of the jet. Mosiac radar
already shows an increasing coverage and intensity of
precipitation developing.

Decent dynamics will occur between 04-13Z time-frame spreading
widespread precipitation across the region. Enough dynamic cooling
and closer proximity to colder airmass west and northwest of area
will allow the northern Plateau to change quickly over the snow.
This is being advertised by the SPC HRRR Browser. Expect several
hour period of light to moderate snow there between 06-12Z with
accumulations of 1 to 3 inches possible over mainly grassy and
elevated surfaces. However, secondary roadways and higher
elevations of interstate 75 on Jellico mountain may experience
travel concerns.

As dynamics lifts northeast Friday morning cold air aloft will
steepen the lapse rates with models showing 40-80 J/Kg of CAPE.
This will be enough to keep scattered showers in the forecast.
Also, orographic lift will increase as surface low lifts
northeast and high pressure builds into the region tightening the
pressure gradients. Windy conditions will develop Friday with
westerly winds of 15 to 30 mph.

Made some minor changes to hourly temperature forecast especially
across the northern Plateau.

&&

.AVIATION...
06Z TAF DISCUSSION.

Upper level trough swinging through the area will produce
scattered rain showers at CHA and TYS and some snow at TRI.
Flight conditions will mostly be MVFR/IFR through the night and
into tomorrow morning and then transitioning back to VFR by
tomorrow afternoon at CHA and TYS.

Winds will continue to increase from the west as we go through the
morning hours due to the tightening pressure gradient from the
trough swinging through. Gusts over 25kts are possible at TYS and
TRI.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             42  32  50  31  58 /  30  20  20  10  10
Knoxville McGhee Tyson Airport, TN  39  31  46  29  55 /  50  10  40  20  10
Oak Ridge, TN                       39  30  46  28  55 /  50  10  40  10  10
Tri Cities Airport, TN              38  27  42  28  51 /  70  30  40  30  10

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Winter Weather Advisory until 4 PM EST this afternoon for Blount
     Smoky Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky
     Mountains-Southeast Carter-Southeast Greene-Southeast
     Monroe-Unicoi.

     Winter Weather Advisory until 1 PM EST /noon CST/ this afternoon
     for Bledsoe-Campbell-Claiborne-Morgan-Scott.

VA...Winter Weather Advisory until 4 PM EST this afternoon for
     Russell-Wise.

     Winter Weather Advisory until 1 PM EST this afternoon for Lee.

&&

Hazardous Weather Outlook...UPDATED
National Weather Service Morristown TN
944 PM EST Thu Feb 6 2020

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-080245-
Cherokee-Clay-Scott-Campbell-Claiborne-Hancock-Hawkins-Sullivan-
Johnson-Morgan-Anderson-Union-Grainger-Hamblen-Northwest Cocke-
Cocke Smoky Mountains-Northwest Greene-Southeast Greene-
Washington-Unicoi-Northwest Carter-Southeast Carter-Roane-Loudon-
Knox-Jefferson-Northwest Blount-Blount Smoky Mountains-
North Sevier-Sevier Smoky Mountains-Sequatchie-Bledsoe-Rhea-Meigs-
McMinn-Northwest Monroe-Southeast Monroe-Marion-Hamilton-Bradley-
West Polk-East Polk-Lee-Wise-Russell-
944 PM EST Thu Feb 6 2020 /844 PM CST Thu Feb 6 2020/

This Hazardous Weather Outlook is for portions of southwest North
Carolina...east Tennessee and southwest Virginia.

.DAY ONE...Tonight and Friday

...Accumulating snowfall expected across the northern Plateau and
higher elevations of East Tennessee and southwest Virginia late
tonight and Friday...

Cold air will spill into the region overnight behind a cold
front. Another storm system will also move northeast across the
area tonight and Friday. Widespread precipitation will develop
with the rain mixing with and changing to snow across the northern
Plateau, and higher elevations of east Tennessee and southwest
Virginia.

Snow accumulations of 1 to 3 inches are expected with locally
higher amounts up to 5 inches possible across the highest
elevations of the Smoky Mountains.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

The wet pattern will continue into next week with several rounds
of rainfall expected, mainly Monday and Monday night, and again
next Thursday. Given the saturated soils and high stream levels,
any additional rainfall may cause flooding issues.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.