054
FXUS64 KMRX 030036
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
836 PM EDT Thu May 2 2024

...New UPDATE...

.UPDATE...
Issued at 825 PM EDT Thu May 2 2024

POPs were nudged up slightly in the southern Valley and southern
Plateau late tonight into the early morning hours. Consshort and
HRRR guidance is somewhat high in that area but CAMs have very
spotty light activity, so I was hesitant to increase POPs much
before sunrise. That was the only minor change to the forecast for
tonight. Thunder potential is fairly low through sunrise but a
few strikes will be possible. Expect increasing clouds overnight.

&&

.SHORT TERM...
(This evening through Friday)
Issued at 306 PM EDT Thu May 2 2024

Key Messages:

1. Increasing chances for rain and storms tonight and into Friday.


2. While severe weather is not expected, a few instances of 1/4"
hail and wind gusts up to 40 mph are possible tomorrow afternoon with
any stronger storms.

Clouds increase tonight as high pressure shifts east due to a
shortwave pushing in from the west. This shortwave will bring
increasing chances of POPs, mainly after midnight. Precip most
likely arrives onto the Cumberland Plateau somewhere around
daybreak, then spreading further east into the east TN Valley
through mid to late morning. From late morning into early
afternoon we should see enough instability develop to produce a
few scattered thunderstorms. Shear profiles remain very weak so no
threat of severe weather. HREF SBCAPE probabilities of 500 J/kg
or greater is around 50%. This lines up with what the HRRR is
showing for tomorrow afternoon with SBCAPE values ranging from 300
to 800 J/kg. 0-6km shear will generally be around 20kts, so
perhaps just enough to produce some 1/4" sized hail with any
stronger updrafts. Along with wind gusts up to 40 mph. Again,
just garden variety thunderstorms. High temps will be a touch
cooler tomorrow with the scattered showers and cloud cover around
with highs in the upper 70s to low 80s.

&&

.LONG TERM...
(Friday night through next Thursday)
Issued at 306 PM EDT Thu May 2 2024

Key Messages:

1. Near normal to above normal temperatures through the long term.

2. Unsettled pattern with chances for showers and thunderstorms each
day of the long term. More diurnal pattern of convection last three
days of the period Tuesday through Thursday next week.

Discussion:

Showers and a few storms will likely be ongoing at the start of the
long term period as another shortwave rolls in from the west. By
Saturday morning, the shortwave should be somewhere between western
and middle TN. This wave will nearly be cutoff from the upper level
flow and be a slow mover. Meaning, shower and storm chances remain
on the high side through the day. While showers and a few storms
will be in place Saturday morning, it looks like the highest chances
occur Saturday afternoon. This is due to increasing instability and
the shortwave pushing further east into our area. As with Friday, any
stronger storms will have the ability to produce small hail and
gusty winds but no severe threats are anticipated at this time due
to weak shear.

On Sunday, this shortwave will still be impacting the area as it
won`t completely lift off to our northeast until Sunday evening.
This means another day of scattered showers and storms, though less
coverage compared to Saturday. No severe threats, just garden
variety storms.

On Monday, yet another shortwave rolls through. You guessed it, more
chances for showers and storms. Tuesday through Thursday, a broad
and deep upper trough sets up across the western and central U.S.
With high pressure to our south, this puts our region in quasi-
zonal, southwesterly, flow pattern. During this time, shower and
storm chances will be more diurnally driven. Also, stronger upper
level winds are progged to move in from the west with the approach
of the trough, which means higher shear. This will set the stage
for an increase in severe weather chances. We remain too far out
for much detail other than to keep an eye on the forecast in the
coming days to see how next weeks` pattern evolves.

&&

.AVIATION...
(00Z TAFS)
Issued at 718 PM EDT Thu May 2 2024

VFR conditions will prevail this TAF cycle. High clouds will move
into the region this evening, lowering by morning (still VFR).
Isolated to scattered rain showers will begin near CHA and TYS in
the morning hours becoming more scattered or numerous by
afternoon. Thunder potential will be low in the morning,
increasing in the afternoon hours but even then thunder may be
more isolated. Kept PROB30 chance until confidence increases, a
TEMPO may be more appropriate in later TAF issuances.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             66  81  64  81 /  40  60  60  80
Knoxville McGhee Tyson Airport, TN  62  81  64  78 /  10  70  60  90
Oak Ridge, TN                       62  81  63  78 /  10  70  60  80
Tri Cities Airport, TN              58  82  61  75 /   0  40  50  90

&&

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

$$

SHORT TERM...
AVIATION...McD