646
FXUS64 KMRX 190709
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
309 AM EDT Wed Jun 19 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(Today and tonight)
Issued at 249 AM EDT Wed Jun 19 2024

Key Messages:

1. Hot and dry conditions continue with strong ridging in place.

Discussion:

NAFES anomalies depicts a strong upper ridge persists across the
mid-Atlantic states into the Tennessee valley and Appalachians.
Model soundings show PWs in the bottom quartile with a subsidence
inversion between the 850-700mb layer.

A strong dry lapse rate becomes evident this afternoon up to this
layer which will mix drier air to the surface. Blended the NBM and
NBM 10th percentile dewpoints to better reflect this dry airmass.
The easterly flow around the surface ridge across the region will
produce some weak downslope into the valley as well lowering
dewpoints.

Even though a good deal of ci/cs high level cloudiness is expected
today, the dry air will allow temperatures to warm into the lower
90s most locations in the valley. The heat and dry condtions will
increase the threat of flash drought conditions for much of the
area.

The dry air will allow temperatures to cool into the 60s area-wide
tonight under mostly clear sky.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 249 AM EDT Wed Jun 19 2024

.LONG TERM...(Thursday night through Tuesday)

Key Messages:

1. Above average temperatures continue with strong ridging in place.

2. Diurnal convection probabilities increasing Sunday into early
next week.

Discussion:

Anomalously strong ridging continues across the Eastern CONUS late
week through the weekend with 500mb heights of 594 dam across the
Tennessee and Ohio Valleys. NAEFS anomalies show this near the max
of climatology. The 850mb ridge also remains directly over the Ohio
Valley with weak easterly flow resulting in subsidence and limited
moisture transport across the region. This will keep LFC heights
higher each afternoon with limited probabilities for diurnal
convection on Friday and Saturday.

The upper ridge retrogrades and flattens across the Ohio Valley on
Sunday as a shortwave trough and associated surface frontal features
moves eastward across the Great Lakes. The 850mb ridge shifts east
with southerly flow bringing increasing moisture beginning Sunday.
This increased moisture and lower upper heights will increase
instability with higher probabilities for diurnal convection into
early next week.

&&

.AVIATION...
(06Z TAFS)
Issued at 1253 AM EDT Wed Jun 19 2024

VFR conditions at all TAF sites throughout the forecast. Winds
will be light easterly due to surface ridging just north of the
area.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             91  70  92  71 /   0   0   0   0
Knoxville McGhee Tyson Airport, TN  91  67  92  69 /   0   0   0   0
Oak Ridge, TN                       90  67  92  70 /   0   0   0   0
Tri Cities Airport, TN              91  63  90  64 /   0   0   0   0

&&

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

$$

SHORT TERM...DH
AVIATION...DH