Mesoscale Discussion 101

Issued

Feb 21, 2003, 1:43 AM CST (07:43 UTC)

Expired

Feb 21, 2003, 3:45 AM CST

In force

2 hr

Issued by

the Storm Prediction Center

Counties Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Evangeline Parish, LA, Jefferson Davis Parish, LA, Lafayette Parish, LA, Saint Landry Parish, LA, Vermilion Parish, LA, Vernon Parish, LA, Chambers County, TX, Hardin County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Newton County, TX, Orange County, TX

The Lake Charles radar (KLCH), 16 km from the middle of the area, began a volume at 07:42 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.

• Tornado Watch 10Feb 21, 4:25 AM CST

185 
ACUS11 KWNS 210744
SWOMCD
SPC MCD 210743 
TXZ000-LAZ000-210945-

MESOSCALE DISCUSSION 0101
NWS STORM PREDICTION CENTER NORMAN OK
0143 AM CST FRI FEB 21 2003

AREAS AFFECTED...SERN TX / SWRN LA

CONCERNING...SEVERE THUNDERSTORM POTENTIAL...HEAVY RAINFALL 

VALID 210743Z - 210945Z

SOME ORGANIZATION OF ONGOING CONVECTION IS EVIDENT IN RADAR
REFLECTIVITY OVER EXTREME SERN TX / SWRN LA...BUT STORMS LIKELY
REMAIN ELEVATED.  WW NOT ANTICIPATED ATTM.



VERY STRONG DEEP-LAYER WIND FIELD IS OBSERVED ACROSS THIS AREA. 
SELY SURFACE FLOW INDICATED BY SURFACE ANALYSIS VEERS RAPIDLY TO
SWLY AND INCREASES TO 50 KT AT H8 AND TO 75 KT AT H5 ACCORDING TO
LATEST KLCH /LAKE CHARLES LA/ WSR-88D VWP.  ONGOING CONVECTION
ACROSS THIS AREA HAS SHOWN SOME ORGANIZATION / SMALL BOWING
FEATURES OVER THE PAST HOUR.



HOWEVER...EVENING LCH RAOB AND MODEL SOUNDS ACROSS THIS AREA
INDICATE THAT STORMS REMAIN ELEVATED -- PROBABLY BASED ABOVE 850
MB...WHICH SUGGESTS THE POTENTIAL FOR STRONG WINDS REACHING THE
SURFACE REMAINS LOW DESPITE STRONG WIND FIELD.	SATURATED EVENING
SOUNDING AT LCH ALSO SUGGESTS LITTLE THREAT FOR HAIL.



DRIER MID-LEVEL AIR APPEARS TO BE APPROACHING THIS REGION BASED
ON LATEST WV IMAGERY -- WHICH MAY RESULT IN SOME STEEPENING OF
MID-LEVEL LAPSE RATES AND THUS AN INCREASE IN INSTABILITY --
WHICH COULD INCREASE THE THREAT FOR HAIL.  ADDITIONALLY...MODELS
SUGGEST THAT CONTINUED WARMING / MOISTENING BELOW 850 MB WILL
ALLOW STORMS TO BECOME LESS ELEVATED WITH TIME -- PERHAPS
INCREASING THE THREAT FOR DAMAGING WINDS.  WE WILL CONTINUE TO
MONITOR THIS REGION FOR ANY INCREASE IN SEVERE THREAT.



OF GREATER THREAT ATTM APPEARS TO BE THE POTENTIAL FOR HEAVY
RAINFALL.  SATURATED EVENING LCH SOUNDING SHOWS 1.5 INCHES
PRECIPITABLE WATER...AND TRAINING OF ECHOES IS OCCURRING ACROSS
JEFFERSON AND ORANGE COUNTIES IN TX AND CALCASIEU PARISH IN LA AS
STORMS CONTINUE DEVELOP INVOF GALVESTON BAY AND MOVE NEWD. 
EXPECT RAINFALL RATES OF LOCALLY 2 INCHES PER HOUR ACROSS THESE
AND ADJACENT COUNTIES.

..GOSS.. 02/21/2003

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

30629452 31219298 31159174 30339154 29769193 29599222
29619272 29749332 29679406 29429462 29639490 30229486

Mesoscale Discussions in Louisiana, 2003Mesoscale Discussions in Texas, 2003Every mesoscale discussion in 2003

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.