Mesoscale Discussion 112

Issued

Feb 17, 2021, 5:38 PM CST (23:38 UTC)

Expired

Feb 17, 2021, 8:15 PM CST

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

Counties Jefferson Parish, LA, Lafourche Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Terrebonne Parish, LA, Harrison County, MS

183 
ACUS11 KWNS 172338
SWOMCD
SPC MCD 172338 
MSZ000-LAZ000-180215-

Mesoscale Discussion 0112
NWS Storm Prediction Center Norman OK
0538 PM CST Wed Feb 17 2021

Areas affected...Southeast Louisiana...Far Southern Mississippi

Concerning...Severe potential...Watch possible 

Valid 172338Z - 180215Z

Probability of Watch Issuance...40 percent

SUMMARY...A severe threat may develop across parts of southeast
Louisiana and far southern Mississippi this evening. A tornado
and/or wind damage will be possible with the strongest of cells. As
the storms gradually intensify, weather watch issuance will need to
be considered.

DISCUSSION...The latest water vapor imagery shows an upper-level
trough extending from west Texas southward into northeastern Mexico.
Southwest mid-level flow is present across much of the southern
Plains and lower to mid Mississippi Valley. At the surface, a low is
present in the northern Gulf of Mexico with a warm front located
from near the coast of southeast Louisiana extending eastward into
the far northern Gulf of Mexico. Surface dewpoints near and to the
south of the warm front are in the lower 60s F. This airmass will
spread northward across far southeast Louisiana early this evening
and into far southern Mississippi by late evening. Thunderstorms are
expected to develop along or near the warm front this evening,
tracking eastward across the central Gulf Coast. Although the
strongest instability will remain offshore, RAP forecast soundings
in far southeast Louisiana increase MLCAPE to near 1000 J/kg and
maintain 0-6 km shear near 60 Kt. 0-3 km storm relative helicity in
the 300-400 m2/s2 range will likely support a severe threat, with a
tornado and/or wind damage possible with the strongest of storms.
The severe threat may eventually affect far southern Mississippi as
low-level moisture advection continues into the late evening.

..Broyles/Hart.. 02/17/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LIX...LCH...

LAT...LON   28998877 29418851 29938840 30308849 30488872 30548904
            30149021 29829098 29549140 29389141 29089130 28949055
            28898942 28998877

Mesoscale Discussions in Louisiana, 2021Mesoscale Discussions in Mississippi, 2021Every mesoscale discussion in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.