Tornado Threat Increasing for Southern Louisiana

With a landfalling tropical cyclone, we see an increasing tornado threat especially in the left front quadrant, and that will soon be the case across the southern parishes of Louisiana, including southern Terrebonne and Lafourche parishes.

We will deal with a severe weather threat in Alabama tomorrow. More about that in a bit.

Other Central Alabama impacts will include 2-4 inches of rain and wind gusts of up to 40 mph starting tonight and lasting through tomorrow.

Mesoscale Discussion 2051
NWS Storm Prediction Center Norman OK
0719 AM CDT Wed Sep 11 2024

Areas affected…southeastern Louisiana coastal areas

Concerning…Severe potential…Watch possible

Valid 111219Z – 111545Z

Probability of Watch Issuance…60 percent

SUMMARY…The risk for occasional tornadoes may begin to increase
near southeastern Louisiana coastal areas by late morning (10
AM-Noon). Trends are being monitored for the possibility of a
tornado watch.

DISCUSSION…The center of Francine has been migrating across and
northeast of the Gunnison Oil Platform vicinity of the northwestern
Gulf of Mexico during the past hour or so, and is still roughly 170
miles from its forecast south central Louisiana coastal landfall
later today. However, the leading edge of a broader convective
precipitation shield preceding Francine is beginning to overspread
coastal areas, accompanied by saturating thermodynamic profiles with
lapse rates trending moist adiabatic in mid-levels.

In the wake of this regime, and with the continued approach of
Francine, model forecast soundings suggest that a subtle increase in
boundary-layer temperatures and dew points may contribute to modest
destabilization by midday along coastal areas from west of
Boothville into the Vermilion Bay vicinity. It appears that this
will coincide with more notable strengthening of low-level wind
fields, which are forecast to contribute to enlarging low-level
hodographs increasingly supportive of convection with embedded
low-level mesocyclones potentially capable of producing tornadoes.

..Kerr/Edwards.. 09/11/2024

Category: ALL POSTS, Tropical