Severe Thunderstorm Warning 76, NWS Morristown, TN

Area Forecast Discussion
National Weather Service Morristown TN
327 AM EDT Wed May 24 2017

.Short Term (Today and Tonight)...An active day across the
Tennessee Valley and southern Appalachians. A deep upper trough
will dig southeast into the Tennessee Valley with jet dynamics
moving across the Region. First wave of energy is currently moving
across northern Alabama. This wave will move northeast across the
area this morning with showers and embedded thunderstorms. As
another jet streaks moves across the Region late this morning and
afternoon, pressure falls are expected across the lower
Ohio/northern Tennessee Valleys with a surface low moving
northeast into east Kentucky/southern Ohio.

The pressure falls will help induce a boundary layer jet of 35kts
across the Region improving the shear profile. A surface boundary
will move across the area late this morning and afternoon with
moist and unstable air ahead of the frontal boundary. Main
question is if there will be enough breaks in the cloud cover
today allowing the low-level airmass to destabilize. Latest high
resolution models, such as the HRRR model do show individual
strong convection developing. Due to the expected shear, low-
topped supercell structures are anticipated later today with the
SPC HRRR Browser depicting good updraft helicity for the storms
across the eastern/northern counties between 16-20Z.

Given the above isolated tornadoes are a concern Today for areas
mainly along and east of interstate 75. Besides the tornado
threat, cold air aloft and low-level jet may produce hail and
damaging winds with the stronger storms.

Frontal boundary will move east of the area by early evening with
shower coverage diminishing for tonight. A cool night is in store.

.Long Term (Thursday through Tuesday)...
Confidence in forecast through Saturday is fairly high with models
in good agreement on a largely amplified wave pattern aloft.
GFS Ensemble as well as GFS and ECMWF begin to diverge slightly
Sunday through Tuesday as next fairly broad 500 mb low begins to
drive SE across the Great Lakes area.

By Thursday morning, 500 mb low over central Ohio extends trough
axis south over East TN. As trough axis swings eastward through
Friday morning expect to see some showers and thunderstorms
particularly over the northern half of the area that will diminish
with sunset Thursday night as a broad ridge builds over the area on
Friday.

Shortwave trough is fcst to move across the broad ridge on Saturday.
With it, expect chance for some showers and thunderstorms Saturday
afternoon. Greatest threat for strong storms on Saturday will likely
lie in SW Virginia and NE Tennessee where nose of 300 mb jet pushes
across the ridge axis late Saturday.

Next front approaches the area Sunday before moving through on
Monday. Digging 500 MB trough coupled with surface dewpoint climbing
back into the upper 60s across a large portion of the area, will
result in greater coverage of showers and thunderstorms on Sunday
with potential for more strong to severe storms by afternoon.

Broad trough aloft dominates the eastern third of the US on Monday
into Tuesday with instability on Monday holding up chance POPs into
Tuesday before significant dry air aloft lowers chances on
Tuesday.

Thursday's temperatures expected to be on the cool side with cloudy
skies and the upper trough swinging over the area. However,
temperatures will rebound nicely on Friday to near seasonal norms
through the remainder of the forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             72  55  75  56 /  90  50  30   0
Knoxville McGhee Tyson Airport, TN  73  54  70  54 /  90  40  50  10
Oak Ridge, TN                       72  54  71  55 /  90  40  40  10
Tri Cities Airport, TN              73  53  64  52 /  90  60  70  30

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...None.
VA...None.
&&

Hazardous Weather Outlook
National Weather Service Morristown TN
347 AM EDT Wed May 24 2017

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-250800-
Cherokee-Clay-Scott TN-Campbell-Claiborne-Hancock-Hawkins-
Sullivan-Johnson-Morgan-Anderson-Union-Grainger-Hamblen-
Northwest Cocke-Cocke Smoky Mountains-Northwest Greene-
Southeast Greene-Washington TN-Unicoi-Northwest Carter-
Southeast Carter-Roane-Loudon-Knox-Jefferson-NW 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-Scott-Russell-Washington-
347 AM EDT Wed May 24 2017 /247 AM CDT Wed May 24 2017/

This Hazardous Weather Outlook is for portions of Southwest North
Carolina...East Tennessee and Southwest Virginia.

.DAY ONE...Today and Tonight

...Severe Thunderstorms Possible Today, especially areas along and
east of interstate 75...
...Main concern Today will be isolated tornadoes, hail up to
quarter size, damaging winds and localized heavy rainfall...

A strong upper level storm system will move across the Tennessee
Valley Today. The airmass across the area will be moist and
marginally unstable with favorable turning of the wind. The main
question is how much breaks in the cloud cover occur allowing the
airmass to become unstable.

If the airmass is allowed to become unstable to produce severe
thunderstorms, the main concern will be isolated tornadoes, hail
up to quarter size, damaging winds and localized heavy rainfall.

The greatest threat of severe storms will be along and east of
interstate 75, and between Noon and 5 pm ET. Please stay tuned to
the latest forecast from the National Weather Service.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

...Strong to Severe Thunderstorms are Possible both Saturday and
Sunday Afternoon and Early Evening...

A moist and very unstable airmass will be across the area this
weekend. Scattered showers and thunderstorms are possible each
day. Some of these storms may be severe with damaging winds, hail
and locally heavy rainfall possible with the stronger
thunderstorms.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed Today, and again this weekend.

Special Weather Statement
National Weather Service Morristown TN
449 AM EDT Wed May 24 2017

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-242000-
Cherokee-Clay-Scott TN-Campbell-Claiborne-Hancock-Hawkins-
Sullivan-Johnson-Morgan-Anderson-Union-Grainger-Hamblen-
Northwest Cocke-Cocke Smoky Mountains-Northwest Greene-
Southeast Greene-Washington TN-Unicoi-Northwest Carter-
Southeast Carter-Roane-Loudon-Knox-Jefferson-NW 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-Scott-Russell-Washington-
Including the cities of Murphy, Hayesville, Oneida, La Follette,
Tazewell, Sneedville, Rogersville, Kingsport, Bristol,
Mountain City, Wartburg, Clinton, Oak Ridge, Maynardville,
Rutledge, Morristown, Newport, Cosby, Greeneville, Cedar Creek,
Johnson City, Erwin, Elizabethton, Roan Mountain, Kingston,
Lenoir City, Knoxville, Dandridge, Maryville, Cades Cove,
Sevierville, Gatlinburg, Dunlap, Pikeville, Dayton, Decatur,
Athens, Madisonville, Coker Creek, Jasper, Chattanooga,
Cleveland, Benton, Ducktown, Jonesville, Wise, Norton, Gate City,
Lebanon, and Abingdon
449 AM EDT Wed May 24 2017 /349 AM CDT Wed May 24 2017/

...Severe Thunderstorms Possible Today, especially areas east of
interstate 75...

A strong upper level storm system will move across the Tennessee
Valley Today. The airmass across the area will be moist and
marginally unstable with favorable turning of the wind. The main
question is how much breaks in the cloud cover occur allowing the
airmass to become destabilize.

If the airmass is allowed to become unstable, some of the storms
may become severe. The main concern will be isolated tornadoes,
hail up to quarter size, damaging winds and localized heavy
rainfall.

The greatest threat of severe storms will be east of interstate
75, and between Noon and 5 pm ET. Please stay tuned to NOAA
Weather Radio and other local media for further details or
updates.

Special Weather Statement
National Weather Service Morristown TN
608 AM CDT WED MAY 24 2017

TNZ098-241200-
Marion TN-
608 AM CDT WED MAY 24 2017

...SIGNIFICANT WEATHER ADVISORY FOR MARION COUNTY UNTIL 700 AM CDT...

At 607 AM CDT, Doppler radar was tracking a strong thunderstorm 7
miles northwest of Stevenson, or 9 miles west of Bridgeport, moving
northeast at 35 mph.

Pea size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Jasper, South Pittsburg, Whitwell, Kimball, Monteagle, Powells
Crossroads, Orme, Chimneys S.p., Martin Springs, Fiery Gizzard S.p.,
Foster Falls S.p., Griffith Creek, Haletown (guild), Hicks Gap S.p.,
Sequatchie Cave, New Hope and Lone Oak.

LAT...LON 3524 8585 3524 8582 3522 8577 3522 8574
      3524 8569 3529 8571 3529 8569 3531 8565
      3532 8556 3519 8539 3518 8539 3501 8543
      3498 8548 3499 8586 3522 8586 3522 8587
TIME...MOT...LOC 1107Z 243DEG 35KT 3497 8589

EJH