Alert archive / Louisiana / Mesoscale Discussions in 2011

Mesoscale Discussion 86

February 3, 201129 parishes in Louisiana; 18 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Feb 3, 2011, 10:36 PM CST for 29 parishes in Louisiana; 18 counties in Mississippi. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Feb 3, 2011, 10:36 PM CST (04:36 UTC)
Expired: Feb 4, 2011, 4:30 AM CST
In force: 6 hr
Issued by: the Storm Prediction Center

All 47 counties

Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Evangeline Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Richland Parish, LA, Saint Landry Parish, LA, Tensas Parish, LA, Vernon Parish, LA, West Carroll Parish, LA, West Feliciana Parish, LA, Winn Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Leake County, MS, Lincoln County, MS, Madison County, MS, Rankin County, MS, Sharkey County, MS, Warren County, MS, Wilkinson County, MS, Yazoo County, MS

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 4.6 hours before the alert went out and 179 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 834 m above ground
0-6 km bulk shear: 87 kt
0-1 km storm-relative helicity: 229 m²/s²
0-3 km storm-relative helicity: 299 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

604 
ACUS11 KWNS 040437
SWOMCD
SPC MCD 040436
MSZ000-LAZ000-ARZ000-TXZ000-041030-

MESOSCALE DISCUSSION 0086
NWS STORM PREDICTION CENTER NORMAN OK
1036 PM CST THU FEB 03 2011

AREAS AFFECTED...SWRN LA NEWD INTO W CENTRAL AND SWRN MS

CONCERNING...FREEZING RAIN

VALID 040436Z - 041030Z

FREEZING RAIN RATES IN EXCESS OF .05"/HR SHOULD SPREAD/EXPAND ACROSS
THE DISCUSSION AREA OVER THE NEXT FEW HOURS...WITH ICE ACCUMULATION
ON ROADS EXPECTED TO RESULT IN HAZARDOUS TRAVEL CONDITIONS.

LOW-LEVEL SLY/SWLY FLOW IN THE 850 TO 700 MB LAYER IS FORECAST TO
CONTINUE INCREASING WITH TIME...AS AN UPPER TROUGH CENTERED OVER
TX/NRN MEXICO PROGRESSES EWD.  EVIDENCE OF INCREASING LARGE-SCALE
ASCENT IS REVEALED BY WV AND RADAR IMAGERY ACROSS CENTRAL AND NRN TX
ATTM...AS INCREASING LOW-LEVEL WARM ADVECTION ASSOCIATED WITH THE
AFOREMENTIONED STRENGTHENING OF THE LOW-LEVEL FLOW CONTINUES BENEATH
MID-LEVEL CVA.

AS THIS ZONE OF FAVORABLE QG FORCING SPREADS EWD...EXPECT
PRECIPITATION ONGOING ACROSS CENTRAL AND NERN LA TO INCREASE OVER
THE NEXT SEVERAL HOURS.  WHILE MOST PRECIPITATION EXPANDING ATTM
FARTHER W ACROSS NRN TX SHOULD REMAIN IN THE FORM OF SNOW GIVEN
COOLER AIR ALOFT...CONTINUED WARM ADVECTION ATOP A SUB-FREEZING
LOWER TROPOSPHERE E OF THE SABINE RIVER WILL ALLOW PRECIPITATION TO
REMAIN LIQUID -- FALLING AS FREEZING RAIN.

AREAS OF NWRN LA -- NW OF A LINE FROM ROUGHLY LFK /LUFKIN TX/ TO ELD
/EL DORADO AR/ -- MAY EXPERIENCE PRIMARILY SNOW...AS THE LOWER
TROPOSPHERE IS LIKELY TO REMAIN BELOW FREEZING ACROSS THIS PORTION
OF THE AREA DESPITE WARM ADVECTION.  HOWEVER...LOCATIONS FARTHER SE
ACROSS MUCH OF LA AND INTO SWRN AND WRN MS WILL LIKELY BE AFFECTED
BY SEVERAL HOURS OF FREEZING RAIN -- WHICH MAY LAST INTO EARLY
MORNING RUSH HOUR IN SOME AREAS.

..GOSS.. 02/04/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

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

LAT...LON   29989285 29999363 30629380 31889320 33189166 33308978
            32788944 31449048 30229200 29989285

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 4, 5:28 AM CST	Mesoscale Discussion	SPC	Avoyelles, Bienville, Bossier, Caddo, Caldwell, Catahoula and 24 more	6 hr

Nearby

Mesoscale Discussions in Louisiana, 2011 Mesoscale Discussions in Mississippi, 2011 Every mesoscale discussion in 2011

Sources

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.