Mesoscale Discussion 71

Issued

Jan 18, 2017, 6:06 PM CST (00:06 UTC)

Expired

Jan 18, 2017, 8:00 PM CST

In force

114 min

Issued by

the Storm Prediction Center

Chance of a watch

5%

Counties Catahoula Parish, LA, Franklin Parish, LA, Grant Parish, LA, LaSalle Parish, LA, Tensas Parish, LA, Claiborne County, MS, Warren County, MS

The Ft Polk radar (KPOE), 151 km from the middle of the area, began a volume at 00:10 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

709 
ACUS11 KWNS 190006
SWOMCD
SPC MCD 190006 
MSZ000-LAZ000-190200-

Mesoscale Discussion 0071
NWS Storm Prediction Center Norman OK
0606 PM CST Wed Jan 18 2017

Areas affected...central Louisiana through southwest Mississippi

Concerning...Severe potential...Watch unlikely 

Valid 190006Z - 190200Z

Probability of Watch Issuance...5 percent

SUMMARY...Threat for a couple of instances of damaging wind and
perhaps a brief tornado will persist through about 02Z. Overall
threat is too marginal for a WW issuance.

DISCUSSION...Early this evening a quasi-stationary front stretches
from south AL through southern MS, central LA, to a weak surface low
in southeast TX. A cold front extends from the low through far
southeast TX and the northwest Gulf. Latest objective analysis shows
the warm sector is only marginally unstable with MLCAPE near or
below 500 J/kg in the presence of weak lapse rates. Showers and
thunderstorms will continue developing in vicinity of the
quasi-stationary front next 2-3 hours. However, overall tendency
should be for storms to begin a gradual, but temporary decrease
through mid evening within zone of weakening forcing for ascent in
wake of low-amplitude shortwave trough moving northeast through the
lower MS Valley. In the meantime, vertical wind profiles with
effective bulk shear from 30-35 kt and modest 0-1 km hodograph size
remain sufficient for a few bowing segments and marginal supercell
structures, especially as storms interact with the stationary front.

..Dial/Edwards.. 01/19/2017

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

ATTN...WFO...JAN...LCH...SHV...

LAT...LON   31929042 31649169 31059313 31529294 32229182 32449063
            31929042

Mesoscale Discussions in Louisiana, 2017Mesoscale Discussions in Mississippi, 2017Every mesoscale discussion in 2017

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; radar from the NEXRAD Level II archive.