Strong Wind in Tennessee, March 4, 2025

Area Forecast Discussion
National Weather Service Memphis TN
1157 AM CST Tue Mar 4 2025

...New MESOSCALE UPDATE...

.KEY MESSAGES...
Updated at 1153 AM CST Tue Mar 4 2025

- A strong storm system will move through the region with severe
  thunderstorms possible this afternoon and evening mainly south
  of a Jonesboro, Arkansas to Jackson, Tennessee line. The
  primary risk will be damaging winds.

- Very strong winds with gusts upwards of 50 mph, are expected
  today. Strong winds will continue into Wednesday.

- Mostly dry weather and seasonal temperatures will return to the
  Mid-South for Wednesday and Thursday. Scattered showers return
  for Friday night through Saturday night.

&&

.UPDATE...
Issued at 1035 AM CST Tue Mar 4 2025

Strong gradient winds are the main story this morning. Winds have
gusted to almost 50 mph across parts of eastern AR ahead of an
approaching occluded front. Gusts over 50 mph are likely this
afternoon as the low level jet core pushes into the area.

A tremendous amount of lift associated with the strong upper low
pivoting through the Southern Plains has resulted in a broad area
of showers across Arkansas this morning with an embedded line of
thunderstorms. As a result, the severe weather risk has
diminished across northeast AR and the Missouri Bootheel. The line
is more vigorous over southern AR and northern Louisiana where it
is tapping into some instability. The question for this afternoon
is whether the line can maintain its intensity as it pivots into
east-central AR and north MS and into a poor thermodynamic
environment. There is still a lot of wind to work with so it will
not take much to bring some higher gusts to the surface as the
line moves through. The tornado risk looks very low as any surface
based instability will remain well south of the region.

&&

.MESOSCALE UPDATE FOR SEVERE WEATHER TODAY...
Issued at 1156 AM CST Tue Mar 4 2025

We're watching the primary line of storms moving into the western
portion of the CWA (eastern AR counties) in the next 60+ minutes.
The environment certainly becomes less favorable farther north as
surface-based instability will be minimal. Farther south into
north MS, there is still a potential for surface-based storms
mainly south of a Marianna, AR, to Tupelo, MS, line. Per the 40 km
RAP, we're likely only looking a a few hundred J/kg of MLCAPE,
but that is often enough to support organized convection in
environments with very strong shear (which is the case today).
Deep-layer shear is quite strong with 0-6 km bulk shear near 60
kts. The 0-3 km layer (which is important for QLCS, or linear,
storm modes), bulk shear is 40-50 kts from the southwest, which is
favorable for mesovortex formation in line segments oriented due
N-S or NW-SE. The 0-1 km storm-relative helicity (think of this as
spin) is quite impressive with values ranging from 250 m2/s2 in
the TN Valley to nearly 800 m2/s2 in southern AR. For context, 0-1
km SRH above 200 m2/s2 is often considered favorable for
tornadoes (given good thermodynamics, which we don't really have
today).

Very strong gradient winds will continue ahead of this line of
storms with gusts to around 50 mph. Winds around 2000 ft above the
surface are from the south at ~60 kts. are As the line of storms
moves through the area, there is a potential for some of this
momentum to be forced to the surface, especially during the late
afternoon and early evening hours. The HRRR is really hitting on
this with wind gusts of 60-70 mph. There is still a lot of
uncertainty in this event but the damaging wind potential looks to
be the main player today. The low tornado/hail probs continue, but
will be a secondary concern.

MJ

&&

.DISCUSSION...
(Today through Monday)
Issued at 300 AM CST Tue Mar 4 2025

A windy morning is on the horizon at this hour with current
temperatures in the mid 50s to lower 60s with an overcast alto
stratus deck building in from the west. A potent upper low is
currently moving across the Central Plains, will track into the
Southern Plains by the afternoon, and eventually into the Upper
Mississippi Valley by this evening. A surface low is currently
located out in front of the potent upper low with an attendant
surface frontal system. The pressure gradient out in front of this
large storm system is pretty tight resulting in gusts to 25 mph
across much of Mid-South this morning. Gradient winds will gust up
to 50 mph through today as our storm system pushes across the
Mid-South. Gusts up to 58 mph are not out of the question as the
front and main line of convection moves across the area, reaching
possible High Wind Warning criteria. However, for now, the current
Wind Advisory will remain and will go into effect at 6AM today.

A line of thunderstorms will also be fixated along the
aforementioned frontal system beginning this afternoon. A few
showers could form out ahead of this main line, beginning after
sunrise this morning, along a few shortwaves out ahead of the
main system. The main line of convection will be entering into a
high shear and low CAPE environment. Shear associated with this
system will be very strong with 0-6 km bulk shear upwards of 70
kts with lack luster MUCAPE values less than 500 J/kg. Thus,
damaging winds will be the primary severe threat this afternoon
into this evening. The best MUCAPE and updraft helicity,
thermodynamic setup, will be over the ArkLaMiss region, pinched
off from the Mid-South. Though, a tornado or two cannot be ruled
out today as wind shear values are so high. This will be a fast
moving system leading to not much of a heavy rainfall threat,
though PWATs are upwards of 1.4", nearing the 90th percentile for
this time of year. Thus, rainfall rates will be decently high
likely aggravating urban areas and small streams.

Best timing for the main line of thunderstorms looks to be around 2
PM entering into eastern Arkansas, Memphis around 3-5 PM, and
exiting the Mid-South by 8PM. Not much lingering showers are
expected behind this system as a pretty decent dry slot moves in
behind. Though, gradient winds will remain elevated with gusts up
to 50 mph Wednesday as the pressure gradient remains pretty tight
with the movement of the potent upper low as it tracks from the
Upper Mississippi Valley and into the Ohio Valley. Thus, the
current Wind Advisory will remain in effect through 6PM Wednesday.
As this upper low pushes east, a few wrap around isolated showers
could track over counties along the Tennessee and Kentucky
stateline, though nothing to write home about.

Temperatures behind today's frontal system will fall below normal
for Wednesday and Thursday with highs in the mid 40s to mid 50s.
Thursday morning will be pretty chilly with lows in the upper 20s to
lower 30s. Thursday, winds finally dampen as the upper-low pushes
east and northwest flow falls back over the region and surface high
pressure builds in. Temperatures will also warm closer to normal by
Friday with highs in the mid 60s to lower 70s. A cold front and cut-
off low pressure system looks to move over the Lower Mississippi
Valley from the southwestern CONUS, bringing scattered showers and
cooler temperatures across the area Friday evening and into
Saturday evening. Behind this front, northwest flow aloft and
surface high pressure builds in bringing dry conditions and
slightly above normal temperatures to begin next workweek.

AEH

&&

.AVIATION...
(18Z TAFS)
Issued at 1110 AM CST Tue Mar 4 2025

Showers and a few thunderstorms have begun to move into western
sections of the Mid-South and will continue to spread eastward
through the afternoon and into this evening. Precipitation should
end across the region before midnight. Along with the precipitation.
MVFR ceilings are expected. Very windy conditions are expected
with wind speeds 15 to 25 knots with wind gusts as high as 40
knots. Winds will be southerly this afternoon and tonight then
shift to the west overnight. Low level wind shear remains possible
through early Wednesday morning.

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Wind Advisory until 6 PM CST Wednesday for ARZ009-018-026>028-
     035-036-048-049-058.

MO...Wind Advisory until 6 PM CST Wednesday for MOZ113-115.

MS...Wind Advisory until 6 PM CST Wednesday for MSZ001>017-020>024.

TN...Wind Advisory until 6 PM CST Wednesday for TNZ001>004-019>022-
     048>055-088>092.

&&

MESOSCALE...MJ
PUBLIC FORECAST...SJM
AVIATION...ARS