991
FXUS64 KMRX 221116 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
716 AM EDT Sat Jun 22 2024

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 316 AM EDT Sat Jun 22 2024

Key Messages:

1. Still hot.

2. Some showers over the plateau and mountains today. Coverage will
be limited though.

Discussion:

Upper ridging will largely remain in control of the weather across
the southeast during the short term, though it will weaken and shift
slightly westward in response to a weak wave moving through the
central plains and upper midwest.

As expected, afternoon cumulus was more prevalent yesterday than the
day before and a few isolated showers were even able to develop
yesterday afternoon. With the ridge further weakening today, expect
the upward trend in cloud cover and shower activity to continue
today. Some of the CAM guidance shows very high PoPs (upwards of 60
percent) over the higher terrain of the plateau and Appalachians.
While I have high confidence that showers will develop, coverage is
less certain I think. There`s no forcing mechanism other than
daytime heating, and For that reason, I think that capping rain
chances at 20-25 percent will suffice.

Otherwise, not much to talk about. Afternoon temps will be warm once
again, with low 90s forecast. Any showers that develop this
afternoon should dissipate within a few hours of sunset.

&&

.LONG TERM...
(Sunday through Friday)
Issued at 316 AM EDT Sat Jun 22 2024

Key Messages:

1. Chances of showers and storms return to the area.

2. Continued above normal temperatures.

At the beginning of this period on Sunday morning, we will be
transitioning out of the pure upper ridge regime as it relocates to
the west and we will be entering a more active upper northwest flow.
And it doesn`t take long for the first shortwave to move through the
area bringing much needed showers and storms Sunday night.

Along with this shortwave will be a very weak cold front that will
bring slightly drier air into the area Monday and into Tuesday, but
then the winds return to the south and bring in more moisture and
another round of showers and storms ahead of the next slightly
stronger cold front in the Wednesday through Thursday timeframe.

Between these two systems Monday night through Tuesday night look
dry.  And then after the second system, things should be drying out
during the day Thursday and through Friday.  In general, the first
system looks like it will only offer up to about a 1/4 inch, with
the second system offering some areas up to about 1/2 inch.  We`ll
get what we can take.

For severe threats on Sunday, the SPC Day 2 Marginal Risk clips our
NW counties.  This seems reasonable, given that the terrain could
get things started there ahead of when the main line of storms comes
into the area.  Also, with a northwest flow, storms that develop in
more favorable areas to the northwest will move fairly quickly
toward our NW corner.  However, it does look like the greater
threats are northwest of our area, and that the bulk of the showers
and storms will move in Sunday evening and overnight when the
airmass has started to stabilize somewhat.  The storm threats will
be outflow/downburst winds.  The flooding threat looks minimal since
it has been dry and the storms will be progressing steadily with
little chances of training, and as mentioned before, precip amounts
are expected to remain light overall.

Looking ahead to the severe threats for the Wednesday/Thursday
event, this system is a little better organized than the Sunday
system, so it bears watching as that system approaches, but as usual
this time of year, the timing of the storms can make a big
difference--storms near max heating being stronger than storms
overnight.

&&

.AVIATION...
(12Z TAFS)
Issued at 715 AM EDT Sat Jun 22 2024

ISOLD to SCT SHRA and perhaps even a few TSRA should develop over
the Appalachians and the Cumberland plateau areas this afternoon.
Do not expect these to be INVOF any terminals, so will stick with
light and variable winds and SCT060 bases to account for expected
CU field.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             94  73  96  75 /  10   0  10  40
Knoxville McGhee Tyson Airport, TN  92  72  93  72 /  10  10  10  60
Oak Ridge, TN                       92  72  93  71 /  10  10  10  60
Tri Cities Airport, TN              91  69  90  70 /  10  10  10  70

&&

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

$$

SHORT TERM...CD
LONG TERM....GM
AVIATION...CD