983
FXUS64 KMRX 222325
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
725 PM EDT Sat Jun 22 2024

...New AVIATION...

.SHORT TERM...
(This evening through Sunday)
Issued at 318 PM EDT Sat Jun 22 2024

The familiar high pressure ridge aloft will be moving westward
during this period, allowing a frontal passage ushered in by a
shortwave crossing the Great Lakes. This front will be
accompanied by convection. Rain chances don`t really pick up until
the latter half of Sunday afternoon, with the best precip chances
actually during the evening. This means we will experience one
more hot summer day Sunday before the front arrives with its
Sunday evening storms and slight cool down Monday. More on that
below.

&&

.LONG TERM...
(Sunday night through next Saturday)
Issued at 318 PM EDT Sat Jun 22 2024

.LONG TERM...
(Sunday Night through Saturday)

Key Messages:

1. Frontal boundaries drive scattered to numerous showers and
thunderstorms on Sunday night and Wednesday/Thursday.

2. Above normal temperatures continue into the upcoming week.

Our period beings with a strong upper level ridge off the Atlantic
coast being forced out by a short wave and a corresponding frontal
boundary.  The front will move into our area from Sunday evening
into Monday morning.  We can expect some scattered to numerous
showers and thunderstorms with the frontal passage.  SPC has the NW
section of our CWA in the Day 2 Marginal Risk, with the main risks
being damaging winds and small to marginally severe hail.  With the
NAM suggesting DCAPE values of around 1000 J/kg, MLCAPE values of
1500-2000 J/kg, and SRH values of around 150 m^2/s^2, storm
organization could be possible in the NW counties of the region, and
this potential will continue to be mentioned in the HWO.
Precipitation amounts look to be a tenth to 1/4 inch, with potential
for higher amounts in isolated thunderstorms.

This will see our CWA return to general northwest flow, driving some
drier air into the area.  However, dewpoints continue to trend high
in the NBM runs, so the forecast will bump down the dewpoint values
and high temperatures behind the frontal passage. Northwesterly flow
will keep the air dryer, however this does not bring an end to the
ongoing excessive heat for the period. This pattern continues until
Wednesday when a 800mb jet begins to transport moist air from the
Gulf of Mexico.

A cold front is expected to sweep across the area from the northwest
on Thursday. While less likely to produce any severe weather, we can
expect rain with accumulation up to 1/2 inch. After the passage of
this front, the GFS indicates a return to a ridging pattern off the
Atlantic Coast.  The return to southerly flow will cause afternoon
showers and storms to be the main cause for any precipitation for
the rest of this period.

&&

.AVIATION...
(00Z TAFS)
Issued at 638 PM EDT Sat Jun 22 2024

VFR conditions at all sites through the period. Main impact will
be stronger winds tomorrow compared to the last few days. TYS and
TRI will see gusts around 18kts out of the southwest from early
afternoon through the end of the period.



&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             73  97  74  95 /  10  20  30  10
Knoxville McGhee Tyson Airport, TN  73  94  72  90 /  10  20  50  10
Oak Ridge, TN                       71  93  71  90 /  10  30  50  10
Tri Cities Airport, TN              69  90  70  85 /  10  20  70  20

&&

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

$$

SHORT TERM...GC
LONG TERM....DGS
AVIATION...