Alert archive / Texas / Mesoscale Discussions in 2009

Mesoscale Discussion 708

May 5, 20097 counties in Oklahoma; 8 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 5, 2009, 12:21 PM CDT for 7 counties in Oklahoma; 8 counties in Texas. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued: May 5, 2009, 12:21 PM CDT (17:21 UTC)
Expired: May 5, 2009, 1:45 PM CDT
In force: 84 min
Issued by: the Storm Prediction Center

Counties Atoka County, OK, Bryan County, OK, Choctaw County, OK, Johnston County, OK, Marshall County, OK, McCurtain County, OK, Pushmataha County, OK, Delta County, TX, Fannin County, TX, Franklin County, TX, Grayson County, TX, Hopkins County, TX, Lamar County, TX, Red River County, TX, Titus County, TX

The radar

The Dallas/Ft Worth radar (KFWS), 187 km from the middle of the area, began a volume at 17:21 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.

The watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 245May 5, 1:40 PM CDT

The nearest sounding before it

Fort Worth, TX (KFWD), launched 12:00Z, 5.4 hours before the alert went out and 168 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: 164 J/kg
Mixed-layer CIN: -169 J/kg
Mixed-layer LCL: 560 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 170 m²/s²
0-3 km storm-relative helicity: 268 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 8.1

Open this sounding in Storm Lab

The text

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

000 
ACUS11 KWNS 051722
SWOMCD
SPC MCD 051721 
ARZ000-TXZ000-OKZ000-051845-

MESOSCALE DISCUSSION 0708
NWS STORM PREDICTION CENTER NORMAN OK
1221 PM CDT TUE MAY 05 2009

AREAS AFFECTED...SERN OK THROUGH NERN TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 051721Z - 051845Z

THREAT FOR ISOLATED LARGE HAIL AS WELL AS A MORE CONDITIONAL THREAT
OF ISOLATED DAMAGING WIND MAY INCREASE THIS AFTERNOON. TRENDS ARE
BEING MONITORED FOR A POSSIBLE WW.

EARLY THIS AFTERNOON A WARM FRONT EXTENDS FROM THE SE U.S. THROUGH
NRN LA AND NRN TX. SURFACE BASED INSTABILITY REMAINS CONFINED TO
ALONG AND SOUTH OF THIS BOUNDARY WITH MLCAPE FROM 2000 TO 2500 J/KG
OVER THE TX WARM SECTOR. HOWEVER...OBSERVATIONAL TRENDS HAVE SHOWN
THE LEADING EDGE OF STRONGER ELEVATED INSTABILITY ADVANCING NWD TO
NEAR THE RED RIVER WITH MUCAPE AOA 1000 J/KG ALONG WITH STEEP MID
LEVEL LAPSE RATES. A SLY LOW LEVEL JET WILL PERSIST OVER N-CNTRL TX
THIS AFTERNOON DOWNSTREAM FROM A SHORTWAVE TROUGH ADVANCING EWD
THROUGH THE HIGH PLAINS. INTERSECTION OF LOW LEVEL JET WITH THE
BAROCLINIC ZONE WILL SUSTAIN A ZONE OF LIFT FROM SERN OK INTO NERN
TX. IN ADDITION...LOW LEVEL THETA-E ADVECTION WILL LIKELY CONTRIBUTE
TO DESTABILIZATION A LITTLE FARTHER NWD WITH TIME. WITH TEMPERATURES
STILL IN THE LOW 60S OVER SRN OK...STORMS REMAIN ELEVATED ABOVE A
STABLE LAYER. HOWEVER...AS STORMS DEVELOP SEWD WHERE SURFACE
TEMPERATURES ARE WARMING INTO THE UPPER 60S TO NEAR 70...SUFFICIENT
DESTABILIZATION OF THE BOUNDARY LAYER MAY OCCUR TO SUPPORT A FORWARD
PROPAGATING MCS ALONG WITH AN INCREASING  THREAT OF ISOLATED
DAMAGING WIND.

..DIAL.. 05/05/2009

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

ATTN...WFO...SHV...TSA...FWD...OUN...

LAT...LON   32839510 33399697 34359730 34659595 34129445 32839510

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 5, 6:40 AM CDT	Mesoscale Discussion	SPC	Beckham, Blaine, Caddo, Canadian, Comanche, Cotton and 13 more	2 hr
May 5, 1:38 PM CDT	Severe Thunderstorm Watch	SPC	Atoka, Bryan, Choctaw, Latimer, LeFlore, McCurtain and 2 more	4 hr
May 5, 3:53 PM CDT	Mesoscale Discussion	SPC	McCurtain	97 min
May 5, 3:06 PM CDT	Mesoscale Discussion	SPC	Callahan, Coleman, Eastland, Jones, Nolan, Palo Pinto and 6 more	54 min
May 5, 5:13 PM CDT	Mesoscale Discussion	SPC	Bosque, Brown, Callahan, Coleman, Comanche, Eastland and 14 more	62 min
May 5, 5:46 PM CDT	Tornado Watch	SPC	Bosque, Brown, Callahan, Coke, Coleman, Comanche and 20 more	6 hr

Nearby

Mesoscale Discussions in Texas, 2009 Mesoscale Discussions in Oklahoma, 2009 Every mesoscale discussion in 2009

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; radar from the NEXRAD Level II archive.