Severe Thunderstorm Warning 67, NWS Morristown, TN

AREA FORECAST DISCUSSION
National Weather Service Morristown TN
302 PM EDT Thu May 19 2022

.SHORT TERM...(Tonight and Friday)...

Key Messages:

1. Continued high uncertainty of strong/severe storm chances across
northeast Tennessee/southwest Virginia.

2. Hot on Friday with highs near record territory.

Discussion:

We continue to watch for convective development this afternoon.
Visible imagery does show an expansive CU field has developed with
only limited vertical development over the past several hours likely
due to an elevated inversion given warming between 850-700mb. Most
recently however, there seems to be some enhancement in the CU
field with towering CU denoted and cooling cloud tops across
northeast Tennessee likely associated with a boundary slowly
lifting north. Confidence on additional convective development is
still low but should be mainly across far northeast Tennessee,
along the TN/KY state line and across southwest Virginia.
Temperatures across the area have risen into the 80s to near 90
with dewpoints in the upper 60s to lower 70s and contributing to
SBCAPEs in the 3-4k J/kg range. LI's are impressive, near -8 to
-10. Such an environment along with steep low and mid level lapse
rates continues to favor strong vertical development if the
appropriate amount of lift can be achieved. It is possible a few
more hours of heating could do the trick or even residual outflow
boundaries.

High DCAPEs, entrainment, and melting hail favors a damaging wind
threat with any storms that can quickly become severe this afternoon
and evening. Further, large vertical accelerations, high CAPE within
the -10C to -30C layer, and at least some vertical shear supports
large hail potential. Even though coverage is still highly
uncertain, feel it appropriate to continue to message the
potential given the current parameter space these storms could
form in. Tornado potential continues to remain low, but not zero.
Widespread flooding risk is low with this event, although
localized flash flooding is certainly possible in areas that see
training storms.

Otherwise tonight should feature lowering PoPs as the boundary layer
stabilizes. Mostly clear skies are expected with mild overnight lows
in the 60s. On Friday, subtropical ridging nudges northward with
increasing heights across the area. 850mb temperatures are expected
to rise to between 20-22C which would favor high temperatures in the
upper 80s to lower 90s. This would put us near record territory at
several places. Luckily mixing should bring dewpoints lower into the
60s helping to lower RH values into the 40 percents.

Diegan

.LONG TERM...(Friday Night through Wednesday Night)...

Key Messages:

1. Very warm temperatures and isolated to scattered showers and
storms expected on Saturday.

2. Showers and storms are likely Sunday and Monday with a cold front
moving through Sunday night then lingering over the Carolinas.

3. Chances for showers and storms will continue into next week after
a cool down on Monday.

Discussion

Friday Night through Monday

Saturday will be hot with ridging over the Southeast and mostly
sunny skies. Instability will be moderate to high Saturday afternoon
with dew points in the 60s and CAPE around 2500 to 3500 J/kg. With
the cold front well to the west and ridging overhead, showers and
thunderstorms will probably be isolated and pulse type. However,
with good instability a few strong storms cannot be ruled out.
Storms may be more scattered over the higher elevations of east
Tennessee. Shower and thunderstorm coverage will increase on Sunday
as the cold front moves closer. Sunday will be the best chance for
rain and storms with the front moving through Sunday night. Severe
potential looks marginal for Sunday. Cloud cover and rain well ahead
of the front will likely squash instability and upper level support
is lacking with the shortwave moving well to the north near the
Great Lakes. Although, dew points look good in the upper 60s and the
surface front looks pretty good. If we are able to get some sunshine
strong storms may be possible in the afternoon and evening hours.
The cold front will move through Sunday night but it will slow and
possibly stall over the Carolinas bringing scattered showers and
thunderstorms to the region on Monday due to overrunning. Monday
will be cooler with highs in 70s.

Tuesday and Wednesday

A ridge will be over the Southeast on Tuesday and Wednesday. High
pressure centered over the Northeast will bring southerly low level
flow to the region. With southwesterly flow in the upper levels,
deep layer moisture advection will enhance rain chances for Tuesday
and Wednesday with the highest POPs in the afternoon and evening
during peak heating. Temps will begin to rebound on Tuesday as
southerly low level winds return with highs in the lower 80s or near
80 in the Tennessee Valley.

McD

&&

.AVIATION...
18Z TAF DISCUSSION.

VFR conditions will prevail over the next 24 hours. Confidence is
still low on convective potential at TYS and TRI this afternoon.
Better chances of seeing TSRA would be near TRI but even the
probability of that is low so will keep VCTS for a couple hours
this afternoon. Winds should remain out of the SW this afternoon
between 5-10 knots with higher gusts possible. Winds should begin
to subside tonight but will increase again Friday morning.

Diegan

&&

.CLIMATE...

Daily Record High Maximum Temperatures

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge
05-20   97(1962)       93(1941)       89(1962)       92(1998)
05-21   95(1962)       95(1941)       93(1941)       94(1948)

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             69  92  70  91  69 /   0   0   0  30  20
Knoxville McGhee Tyson Airport, TN  68  92  69  90  67 /  10   0   0  40  20
Oak Ridge, TN                       66  91  68  89  67 /  10   0   0  30  20
Tri Cities Airport, TN              61  92  64  89  63 /  20  10   0  60  20

&&

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

Hazardous Weather Outlook
National Weather Service Morristown TN
303 PM EDT Thu May 19 2022

NCZ060-061-TNZ012>018-035>047-067>074-081>087-098>102-VAZ001-002-
005-006-008-201915-
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-
303 PM EDT Thu May 19 2022 /203 PM CDT Thu May 19 2022/

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

.DAY ONE...This Afternoon and Tonight

A round of showers and thunderstorms is expected into tonight.
The primary threat will be strong straight line winds and large
hail. If multiple storms move over the same area it could lead to
isolated flooding of low lying areas.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.
Please relay any information about severe weather to the NWS while
following local, state, and CDC guidelines.

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