Severe Thunderstorm Warning 177, NWS Morristown, TN

Area Forecast Discussion
National Weather Service Morristown TN
310 PM EDT Sat Jul 29 2023

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(This evening through Sunday)
Issued at 308 PM EDT Sat Jul 29 2023

Key Messages:

1. A few to several strong to severe storms expected this
afternoon/evening. Greatest chances will along I-40 and northward,
especially across northeast TN and southwest VA.

2. Main threats will be isolated damaging wind gusts and localized
flooding due to heavy rainfall.

Discussion:

Thunderstorms are currently ongoing to our north across central KY
within a weak area of surface convergence. CAMs in good agreement
that this activity continues to develop and move south into
southwest VA and northeast TN around 20Z. Thereafter, these storms
will continue to move south into the central East TN Valley. The
highest coverage of storms is expected along and north of I-40, with
more isolated to scattered activity the further south you go into
the southern TN Valley. Current rap analysis on SPC's meso page
shows robust instability across the area with 4000 to 4500 J/kg of
SBCAPE and 2500 to 3000 J/kg MLCAPE. Thankfully shear is non-
existent so these storms will be of the pulse variety and driven by
afternoon heating and outflows.

The main threats with these storms will be isolated damaging winds
gusts and localized flooding. The wind threat is due to a modest
amount of DCAPE with roughly 1000 J/kg in place. The heavy rainfall
is due to high PW values and good warm layer cloud depths of around
10kt feet. The steering flow is also very weak with 850-300 mb mean
winds of 10 to 15kts. This will allow for slow storm motions thus
increasing the flooding threat for areas that get hit by repeated
rounds of storms. Latest WPC QPF puts 0.75 to 1" of rain in for most
areas across northeast TN and southwest VA this afternoon. Some areas
may receive up to 2" of rainfall if they see repeated storms.

The activity that is currently ongoing across the central east TN
Valley was not forecast well by the CAMS. Given that there are
already storms ongoing, and the environment in place, I expect these
storms to continue before additional activity moves in from the
north. Some of these storms may be strong to severe.

CAMS show the bulk of the activity dying off by midnight, with only
isolated showers and storms thereafter. Areas that receive rainfall
will see locally dense fog overnight. Rainfall chances lower
tomorrow with only slight chance to low end chance POPs in place
during the afternoon hours.

&&

.LONG TERM...
(Sunday night through next Saturday)
Issued at 308 PM EDT Sat Jul 29 2023

Key Messages:

1. Drier weather Monday through Wednesday.

2. Chances for showers and storms return late Wednesday through
Saturday.

Discussion:

Not seeing much in the way of changes with the extended. The pattern
generally remains the same, as we start the period with a ridge axis
located across the four-corners. Further north, low pressure will
remain across Quebec, placing the FA within northwest flow aloft.
Surface high pressure will settle across the Ohio Valley, bringing
northerly wind and a much drier atmosphere. Mostly dry weather is
expected Monday through much of Wednesday. Don't want to completely
rule out a stray shower or two across the mountains, but outside of
that the forecast will stay dry. The caveat remains the potential
for any MCS activity that develops to the northwest and how that
propagates but predictability is still very low. Northerly flow will
certainly keep temperatures cooler, more aligned with climatological
normals.

Chances for precipitation begin to increase late Wednesday
associated with a passing disturbance aloft. With high pressure
moving off toward the east, southerly flow will increase bringing
better moisture back into the area. By late this week and into the
weekend, an area of low pressure is progged to lift into the Great
Lakes bringing a cold front through or near the area. This will
provide additional chances of showers and storms.

&&

.AVIATION...
(18Z TAFS)
Issued at 137 PM EDT Sat Jul 29 2023

Increasing chances of thunderstorms this afternoon and evening,
especially for TRI. VFR conditions at CHA through the period. VFR
at TYS except for a tempo MVFR due to this evenings storms. TRI
will begin VFR, then tempo MVFR with the afternoon/evening
storms. TRI will likely see fog tonight due the expected
rainfall with IFR conditions expected late, then a TEMPO for
exceeding runway minimums due to VIS tomorrow morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             96  74  94  71 /  10  30  30  10
Knoxville McGhee Tyson Airport, TN  94  72  91  69 /  40  40  20  10
Oak Ridge, TN                       94  72  90  68 /  40  40  20  10
Tri Cities Airport, TN              92  69  87  65 /  80  50  20  20

&&

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

SHORT TERM...
LONG TERM....
AVIATION...

Hazardous Weather Outlook
National Weather Service Morristown TN
318 PM EDT Sat Jul 29 2023

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-301930-
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-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-Scott VA-Russell-Washington VA-
318 PM EDT Sat Jul 29 2023 /218 PM CDT Sat Jul 29 2023/

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

.DAY ONE...This Afternoon and Tonight

A few to several strong to severe storms are expected this
afternoon/evening. Greatest chances will be along I-40 and
northward, especially across northeast TN and southwest VA.

Main threats will be isolated damaging wind gusts and localized
flooding due to heavy rainfall.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not needed at this time.

Special Weather Statement
National Weather Service Morristown TN
1053 AM EDT Sat Jul 29 2023

VAZ006-008-291545-
Washington VA-Russell VA-
1053 AM EDT Sat Jul 29 2023

...A strong thunderstorm will impact portions of central Russell and
central Washington Counties through 1145 AM EDT...

At 1052 AM EDT, Doppler radar was tracking a strong thunderstorm over
Lebanon, moving southeast at 25 mph.

HAZARD...Winds up to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Abingdon, Lebanon, Glade Spring, Damascus, Lindell, Holston,
Hansonville, Emory-Meadow View and Rosedale.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3661 8183 3662 8187 3682 8223 3701 8201
      3694 8182 3693 8184 3680 8171 3676 8168
TIME...MOT...LOC 1452Z 298DEG 21KT 3686 8208

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

TD

Special Weather Statement
National Weather Service Morristown TN
237 PM EDT Sat Jul 29 2023

TNZ035-067-291930-
Roane TN-Morgan TN-
237 PM EDT Sat Jul 29 2023

...A strong thunderstorm will impact portions of southeastern Morgan
and northern Roane Counties through 330 PM EDT...

At 236 PM EDT, Doppler radar was tracking a strong thunderstorm near
Rockwood, moving east at 25 mph.

HAZARD...Winds in excess of 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Oak Ridge, Kingston, Rockwood, Oliver Springs, Midtown, Harriman,
Oakdale, Coalfield, Bradbury and Pine Orchard.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3587 8472 3589 8471 3590 8468 3598 8471
      3601 8474 3606 8473 3603 8433 3589 8432
      3589 8433 3584 8434 3582 8438 3580 8438
TIME...MOT...LOC 1836Z 281DEG 20KT 3596 8466

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

TD

Special Weather Statement
National Weather Service Morristown TN
246 PM EDT Sat Jul 29 2023

TNZ013-036-037-291930-
Anderson TN-Union TN-Campbell TN-
246 PM EDT Sat Jul 29 2023

...A strong thunderstorm will impact portions of northeastern
Anderson, southeastern Campbell and western Union Counties through
330 PM EDT...

At 246 PM EDT, Doppler radar was tracking a strong thunderstorm near
Jacksboro, or near La Follette, moving east at 20 mph.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
La Follette, Jacksboro, Caryville, Rocky Top, Norris, Norris Dam
State Park, Andersonville, Paulette, Big Ridge State Park and Sharps
Chapel.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3637 8379 3617 8387 3617 8390 3616 8391
      3617 8391 3617 8392 3619 8395 3616 8399
      3620 8427 3640 8421
TIME...MOT...LOC 1846Z 281DEG 18KT 3631 8415

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

TD

Preliminary Local Storm Report
National Weather Service Morristown TN
350 PM EDT Sat Jul 29 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0315 PM     Tstm Wnd Dmg     Kingston                35.87N 84.51W
07/29/2023                   Roane              TN   911 Call Center

            Dispatch reported multiple trees and
            powerlines down in Kingston and Harriman.
            Time estimated from Radar.

&&

BW

Special Weather Statement
National Weather Service Morristown TN
405 PM EDT Sat Jul 29 2023

TNZ085-086-292045-
Northwest Monroe TN-McMinn TN-
405 PM EDT Sat Jul 29 2023

...A strong thunderstorm will impact portions of eastern McMinn and
west central Monroe Counties through 445 PM EDT...

At 405 PM EDT, Doppler radar was tracking a strong thunderstorm near
Athens, moving southeast at 15 mph.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Athens, Madisonville, Etowah, Englewood, Niota and Clear Water.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for
east Tennessee.

&&

LAT...LON 3553 8472 3558 8468 3561 8462 3554 8439
      3551 8432 3532 8450
TIME...MOT...LOC 2005Z 295DEG 14KT 3548 8456

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

SR

Special Weather Statement
National Weather Service Morristown TN
408 PM EDT Sat Jul 29 2023

TNZ036-069-292100-
Anderson TN-Knox TN-
408 PM EDT Sat Jul 29 2023

...A strong thunderstorm will impact portions of northeastern Knox
and northeastern Anderson Counties through 500 PM EDT...

At 408 PM EDT, Doppler radar was tracking a strong thunderstorm near
Clinton, moving southeast at 20 mph.

HAZARD...Winds in excess of 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Knoxville, Clinton, Halls, Norris, Andersonville, Maloneyville,
Powell and Norris Dam State Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

A Severe Thunderstorm Watch remains in effect until 1000 PM EDT for
east Tennessee.

&&

LAT...LON 3610 8424 3623 8409 3610 8377 3591 8394
TIME...MOT...LOC 2008Z 294DEG 16KT 3610 8402

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

SR