103
FXUS64 KHUN 080937
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
437 AM CDT Wed May 8 2024

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

.NEAR TERM...
(Today)
Issued at 437 AM CDT Wed May 8 2024

Conditions remain warm, humid and dry across the TN Valley early
this morning, with mild temperatures in the l-m 70s as of this
writing. We are currently watching two areas of convection, with
the first located across KY (which initiated late yesterday
evening in the vicinity of a surface trough/remnant dryline
sagging southeastward into the OH Valley). Present indications are
that this activity should spread generally eastward and will not
have a direct impact on our CWFA through 12Z. The second area of
convection (currently across eastern AR) also developed late
yesterday evening in the vicinity of a separate surface trough
extending southeastward into northern MS/central AL from an area
of low pressure dropping southeastward into western OK. Latest
high-resolution model data suggests that this activity will
gradually weaken as it shifts east-northeastward through 12Z and
should also not have a direct impact on our CWFA aside from
providing high-level anvil debris clouds.

Over the course of the morning, the surface trough to our south
will lift northward through the TN Valley and should become the
effective warm front of the surface low to our west as it ejects
northeastward into central MO by 0Z Thursday. Widespread severe
thunderstorms are expected along and north of this boundary during
the afternoon hours, which will likely lie along an axis from the
Ozarks east-southeastward into the Smoky Mountains. However,
aside from a few morning showers that may occur as the warm front
tracks northward, our region should remain capped and dry for much
of the day, with highs in the mid 80s. That said, we will need to
keep any eye to the southwest late this afternoon, as a few warm
sector supercells may develop across northeastern MS.

&&

.SHORT TERM...
(Tonight through Friday night)
Issued at 437 AM CDT Wed May 8 2024

The forecast for tonight remains rather complicated, largely due
to the weak nature of deep-layer forcing for ascent across our
region and fact that thunderstorms will be tied to processes
occurring well to our northwest. However, at this point, the most
likely scenario seems to be that the risk for severe thunderstorms
across our CWFA may increase as early as the 0-3Z timeframe,
either from isolated cells that develop to our southwest late this
afternoon and spread northeastward, or with development of new
storms along outflow from widespread convection to our north that
may drift southwestward into southern TN/northeast AL. A separate
MCS may also evolve this evening out of convection that develops
late this afternoon along the cyclones cold front (extending from
the low southwestward into north central TX). Precisely where this
system will develop and track is still uncertain, but present
indications are that it would not arrive in our forecast area
until the 6-9Z timeframe at the earliest (and perhaps as much as
3-6 hours later than this). The combination of 40-50 knot WSW flow
aloft and steep mid-level lapse rates atop a moist boundary layer
(featuring dewpoints in the u60s-l70s) will support a risk for
large hail and damaging winds, with a modest SW low-level jet of
25-35 knots providing sufficient shear in the 0-3km layer for a
lower-end risk for tornadoes.

Several CAMs suggest that convective outflow will eventually
outrun the MCS as we move forward in time, with extensive trailing
stratiform rain and embedded thunderstorms expected to gradually
spread southeastward and out of the region by 18Z Thursday. The
actual cold front should shift southeastward late Thursday
afternoon and exit the forecast area during the evening hours, as
another broad complex of thunderstorms tracks eastward along the
central Gulf Coast. Although redevelopment of showers and storms
along the cold front appears unlikely in our region, we have
indicated a low-medium chance POP on Thursday night to account for
some uncertainty regarding the path of the MCS to our south and
potential for the northern edge of the stratiform rain shield to
graze our region.

In the wake of any lingering morning precipitation on Friday, dry
conditions are currently predicted on Friday and Friday night.
However, with a longwave trough expected to cross the region on
Friday and a trailing vort max digging southeastward into the
region Friday night, a fair amount of mid-level cloud cover is
anticipated (and perhaps even a few very light showers). These two
periods will mark the coolest of the forecast, with highs in the
u60s-m70s Friday and lows in the u40s-l50s Friday night.

&&

.LONG TERM...
(Saturday through Tuesday)
Issued at 437 AM CDT Wed May 8 2024

A generally dry weather pattern will continue across the region
this weekend. However, a clipper system diving southeastward into
the western Great Lakes will send a reinforcing cold front through
the region on Saturday, perhaps bringing a few light showers to
locations north of the TN River. Chances for rain will begin to
slowly return to the region as early as Monday, which is when a
series of lower-latitude troughs may initiate the development of
one or more areas of low pressure across the western Gulf of
Mexico that would shift northeastward early next week. Due to
indications of a modifying low-level airmass across the TN Valley,
instability will gradually increase as we move forward to
Tuesday, with a low chance for thunderstorms apparent as well.

&&

.AVIATION...
(06Z TAFS)
Issued at 1248 AM CDT Wed May 8 2024

VFR conditions are currently observed at the HSV/MSL terminals,
but there are indications that low stratus clouds will develop
within the very moist boundary layer, providing MVFR cigs arnd
1500 ft AGL btwn 9-15Z. As the low stratus layer disperses later
this morning, a rapidly destabilizing airmass will support the
development of sct-bkn Cu, with the risk for a few warm sector
TSRA increasing in the 21-03Z timeframe. Although probabilities
for more a more widespread coverage of storms will increase with
time as we approach the end of the TAF period, confidence is not
high enough to introduce anything more than an additional PROB30
group attm. Prevailing sfc flow will remain from the SSW, with
sustained speeds of 5-10 knots (and gusts of 15-20 knots this
aftn).

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...None.
TN...None.

&&

$$

NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...70/DD
AVIATION...70/DD