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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS64 KMRX 221601
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1201 PM EDT Mon Apr 22 2024

...New UPDATE...

.UPDATE...
-- Changed Discussion --
Issued at 1157 AM EDT Mon Apr 22 2024

Overall, only minimal changes were made with the update. Some
gusty winds were seen in the late morning in southern portions of
the area due to initial mixing and a tightened MSLP gradient.
However, everything has balanced out with weather elements only
changed slightly to reflect the latest high-res model guidance.
The main question will be if/where frost products will be needed
for tonight, which will be considered with the afternoon package.
-- End Changed Discussion --

&&

.SHORT TERM...
(Today and tonight)
Issued at 322 AM EDT Mon Apr 22 2024

1. Patchy frost through sunrise for portions of the area. Frost
Advisory remains in effect.

2. Sunny and slightly warmer today, but highs still 5 to 10 degrees
below normal.

Sheltered valleys across the Cumberland Plateau, east TN mountains,
southwest NC, northeast TN, and southwest VA will see areas of frost
through sunrise. A Frost Advisory remains in effect through 9 AM
EDT for these areas. Soundings show elevations that are above
2000 feet stay well mixed through the rest of the morning which
means frost is unlikely.

With high pressure in control, it will be a beautiful and sun-
filled day across the area. Temperatures will be slightly warmer
than yesterday. However, with northerly flow still in place,
highs remain 5 to 10 degrees below normal. The only real target of
opportunity today was an improvement on dewpoints. NBM is
typically too high under a northerly flow pattern. Went with an
NBM, NBM10, and HRRR blend. This resulted in min RH values this
afternoon in the mid 20s to lower 30s for most areas. Winds should
be on the lighter side though so no real fire weather concerns. A
few areas of patchy frost are possible again tonight but
temperatures will be slightly warmer so frost will be more
isolated. No plans for an additional Frost Advisory for tonight
at this time.

&&

.LONG TERM...
(Tuesday through Sunday)
Issued at 322 AM EDT Mon Apr 22 2024

Key Messages:

1. Gradual warming trend expected Tuesday onwards, with dry and
breezy conditions Tuesday afternoon.

2. Low-end rain chances Tuesday night into Wednesday, focused
further north.

3. Temperatures becoming above normal with breezy conditions late
week and into the weekend. Much uncertainty with low-end
shower/storm chances during this time as well.

Discussion:

For Tuesday, shortwave ridging will lead to mostly dry conditions
throughout the day and the main focus will be on fire weather.
Deepening areas of surface low pressure in the Great Lakes region
and off the East Coast will create a tightening pressure gradient,
leading to breezy conditions. While the wind will be from the
southwest and dewpoints will be trending higher, ambient
temperatures will also be trending higher. Combined with efficient
mixing among a dry vertical profile, recent HRRR runs suggest
afternoon RH will once again fall into the 20s.

By Tuesday night into Wednesday morning an upper level disturbance
will result in a shortwave trough digging into the Ohio Valley and
surface low pressure sliding across the Great Lakes region. An
approaching cold front will bring the chance for light rain. Most
guidance suggest the cold front will be washing out as it swings
through the forecast area and only light precipitation is expected.

A more amplified upper level pattern begins to take shape by the end
of the work week. Deep cyclogenesis will occur on the lee side of
the Rockies as upper level troughing settles in atop the western
half of the CONUS. A boundary draped along the southeast United
States and southerly flow suggest the chance for some showers and
perhaps thunderstorms possible Friday into the weekend for portions
of the southeast United States, however, there is still quiet a bit
of uncertainty on the presence of a warm front draped across the
region and its influence on any convective initiation. Latest NBM
runs have trended drier, restricting PoP chances to just slight
chance and along the higher terrain through the weekend. Given the
uncertainty, see no reason to trend against this at this time. Mean
ensemble data suggest that the probability of CAPE greater than or
equal to 500J/kg is 0%, and organized convection will remain to our
west/northwest.

&&

.AVIATION...
(12Z TAFS)
Issued at 655 AM EDT Mon Apr 22 2024

VFR conditions and light northerly winds continue through the TAF
period.

&&

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --
Chattanooga Airport, TN             42  74  53  75 /   0   0  10   0
Knoxville McGhee Tyson Airport, TN  39  72  54  72 /   0   0  10  10
Oak Ridge, TN                       40  72  53  74 /   0   0  20  10
Tri Cities Airport, TN              36  69  50  68 /   0   0  20  20
-- End Changed Discussion --

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
NC...NONE.
TN...NONE.
VA...NONE.
-- End Changed Discussion --
&&

$$

SHORT TERM...JB
LONG TERM....KRS
AVIATION...KRS