Flash Flood Warning 46, NWS Morristown, TN

Area Forecast Discussion
National Weather Service Morristown TN
727 AM EDT Fri Sep 27 2024

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 209 AM EDT Fri Sep 27 2024

Key Messages:

1. Flooding risk will continue through this morning. There is an
increased risk for flash flooding near Hamilton, Marion, and
Sequatchie Counties where a heavier band of rainfall is expected
to train.

2. Strong 40+ mph wind gusts expected area-wide. Wind gusts over
60 mph will be possible in the Knoxville metro area and to the
northeast across the Tri-Cities region and southwest Virginia.
Higher elevations of the mountains and foothills may see wind
gusts over 80 mph.

3. These strong winds, when combined with saturated soils, will
likely result in widespread downed trees and power outages. Be
prepared for prolonged power outages.

Discussion:

Strong winds and tropical downpours are expected as remnants of
Hurricane Helene move through the region today. Helene is
currently (2AM EDT) centered over South Central Georgia and
maintains hurricane status with winds up to 90 mph. Helene will
continue to weaken as it moves through Georgia but its remnants
will enter our forecast area this morning because of the quick
forward speed. That means the strong pressure gradient and
associated wind field will still be very intense across portions
of the Tennessee Valley and Southern Appalachians. Due to the
extratropical transition, the strongest winds will be on the
eastern side of the track. This means the highest probability of
60+ mph wind gusts will be near the Knoxville metro and to the
northeast. Even valley locations around Knoxville, Morristown, and
the Tri- Cities may see wind gusts up to 60 mph on Friday morning
through the early afternoon. Locations near the low pressure
center track that don't see the strong 60+ mph wind gusts will
likely still see wind gusts of at least 40 mph. Ridge tops will
likely see the strongest wind gusts. Combine these winds with
saturated soils with trees full of leaves, and widespread downed
trees are expected. Widespread power outages will likely be the
result with the potential for prolonged power outages.

Tropical downpours are expected with PW values are over 2.0
inches across the southern valley and southern plateau. This area
will be the greatest threat for flash flooding as rain continues,
heavy at times through early afternoon. The flash flooding and
river flooding risk continues area-wide with several rivers at
flood stage or forecast to rise to flood stage overnight and into
Friday. 2 to 4 additional inches of rain are expected through
early afternoon in the East Tennessee mountains, Cumberland
plateau area and the Chattanooga Metro. Elsewhere, rain amounts
will be lower but flooding issues will still be possible given
all the recent rainfall.

Rain will move out and into Middle Tennessee early this afternoon
but some showers will return tonight. Shower activity tonight is
expected to be light. Winds will stay elevated until sunset but
winds will peak this morning and early afternoon.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 209 AM EDT Fri Sep 27 2024

Key Messages:

1. Breezy Saturday morning, winds to continue decreasing. Light rain
showers likely on Saturday, no additional impacts expected.

2. Additional light rain possible primarily in the afternoon Sunday
through Tuesday. Drier thereafter with seasonable temperatures
throughout.

Discussion:

As the forecast heads to Saturday and the weekend, Helene will be
absorbed into the resident upper low that's to our west currently.
This merged pair will be significantly weaker and less impactful
than the weather currently going on. A couple of days of scattered
light rain showers are possible, mostly on Saturday and Sunday as
the upper low slowly moves eastward through the Ohio River valley.
Rain forecast during this period is a half inch of additional rain
over the northern Plateau, amounts closer to a tenth of an inch most
everywhere else. Winds Saturday morning will be a tad breezy still
but will subside through the day. Lots of shear still evident on
Saturday afternoon with the upper low spinning nearby, but lack of
instability should prevent any severe threat.

Eventually as we progress to the midweek, the low will exit to our
east, heights will build back in, and we'll fully begin the drying
out period. Temperatures look to remain seasonably warm, as heights
increase on the backside of the low.

&&

.AVIATION...
(12Z TAFS)
Issued at 659 AM EDT Fri Sep 27 2024

Strong winds and tropical downpours are expected as remnants of
Hurricane Helene move through the region today. Rain will start to
clear out by early afternoon. Strong winds will continue until
around sunset but peak winds will be in the morning and early
afternoon hours. CIGs will improve shortly after the rain moves
out. Lightning potential is fairly low but a few random strikes
cannot be ruled out. Low level wind shear will be possible in the morning
hours if winds aren't mixing down as forecast.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             74  64  72  63 / 100  40  60  20
Knoxville McGhee Tyson Airport, TN  76  64  75  63 /  90  40  60  60
Oak Ridge, TN                       74  62  72  62 / 100  50  60  60
Tri Cities Airport, TN              78  60  77  62 / 100  20  20  40

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...Flood Watch until 2 PM EDT this afternoon for Cherokee-Clay.

     Tropical Storm Warning for Cherokee-Clay.

TN...Flood Watch until 2 PM EDT /1 PM CDT/ this afternoon for
     Anderson-Bledsoe-Blount Smoky Mountains-Bradley-Campbell-
     Claiborne-Cocke Smoky Mountains-East Polk-Grainger-Hamblen-
     Hamilton-Hancock-Hawkins-Jefferson-Johnson-Knox-Loudon-
     Marion-McMinn-Meigs-Morgan-North Sevier-Northwest Blount-
     Northwest Carter-Northwest Cocke-Northwest Greene-Northwest
     Monroe-Rhea-Roane-Scott TN-Sequatchie-Sevier Smoky
     Mountains-Southeast Carter-Southeast Greene-Southeast
     Monroe-Sullivan-Unicoi-Union-Washington TN-West Polk.

     High Wind Warning until 8 PM EDT /7 PM CDT/ this evening for
     Anderson-Bledsoe-Blount Smoky Mountains-Bradley-Campbell-
     Claiborne-Cocke Smoky Mountains-East Polk-Grainger-Hamblen-
     Hamilton-Hancock-Hawkins-Jefferson-Johnson-Knox-Loudon-
     Marion-McMinn-Meigs-Morgan-North Sevier-Northwest Blount-
     Northwest Carter-Northwest Cocke-Northwest Greene-Northwest
     Monroe-Rhea-Roane-Scott TN-Sequatchie-Sevier Smoky
     Mountains-Southeast Carter-Southeast Greene-Southeast
     Monroe-Sullivan-Unicoi-Union-Washington TN-West Polk.

VA...Flood Watch until 2 PM EDT this afternoon for Lee-Russell-Scott
     VA-Washington VA-Wise.

     High Wind Warning until 8 PM EDT this evening for Lee-Russell-
     Scott VA-Washington VA-Wise.

&&

SHORT TERM...McD
LONG TERM....Wellington
AVIATION...McD

Hazardous Weather Outlook
National Weather Service Morristown TN
343 AM EDT Fri Sep 27 2024

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-280745-
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-
343 AM EDT Fri Sep 27 2024 /243 AM CDT Fri Sep 27 2024/

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

.DAY ONE...Today and Tonight

...Remnants of Hurricane Helene expected to impact the Tennessee
Valley and Southern Appalachians Today...

...A Tropical Storm Warning is in effect for Cherokee and Clay
Counties in North Carolina through early afternoon...

...High Wind Warning in effect for all of East Tennessee and
southwest Virginia through this Evening...

...A Flood Watch is in Effect for Flash Flooding Across Portions
of East Tennessee, southwest Virginia, and southwest North
Carolina...

The remnants of Hurricane Helene will bring tropical downpours
mainly this morning. Flash flooding will be possible with an
additional 2 to 4 inches expected in some places.

In addition to the rain, strong winds are forecast. The highest
winds are expected across the higher elevations of the east TN,
southwest VA, southwest NC mountains, and Cumberland Plateau.
However strong pressure gradients will exist across the region and
thus the lower elevations of the Tennessee valley will likely
experience some high winds Friday morning. With soils incredibly
saturated, trees are likely to fall during this period of high
winds.

.DAYS THREE THROUGH SEVEN...Saturday through Wednesday

No additional hazardous weather is expected at this time.
Flood waters will be receding and may still pose a threat before
streams retreat back within their banks.

.SPOTTER INFORMATION STATEMENT...

Reports of wind damage or flooding is very appreciated.

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