Alert archive / Louisiana / Mesoscale Discussions in 2004
Mesoscale Discussion 1721
The Storm Prediction Center issued this mesoscale discussion at Jul 17, 2004, 2:18 AM CDT for 8 counties in Arkansas; 15 parishes in Louisiana; 11 counties in Mississippi. It was in force for 57 min.
The area
The outline as issued.
The facts
- Issued
- Jul 17, 2004, 2:18 AM CDT (07:18 UTC)
- Expired
- Jul 17, 2004, 3:15 AM CDT
- In force
- 57 min
- Issued by
- the Storm Prediction Center
All 34 counties
Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Cleveland County, AR, Drew County, AR, Lincoln County, AR, Union County, AR, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Richland Parish, LA, Tensas Parish, LA, Union Parish, LA, West Carroll Parish, LA, Adams County, MS, Amite County, MS, Claiborne County, MS, Copiah County, MS, Franklin County, MS, Issaquena County, MS, Jefferson County, MS, Lincoln County, MS, Sharkey County, MS, Warren County, MS, Wilkinson County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 162 km from the middle of the area, began a volume at 07:19 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 nearest sounding before it
Jackson, MS (KJAN), launched 00:00Z, 7.3 hours before the alert went out and 152 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.
- Mixed-layer CAPE
- 227 J/kg
- Mixed-layer CIN
- -153 J/kg
- Mixed-layer LCL
- 1375 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 189 m²/s²
- 0-3 km storm-relative helicity
- 424 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted, in the capitals the NWS used until 2016.
826 ACUS11 KWNS 170719 SWOMCD SPC MCD 170718 MSZ000-LAZ000-ARZ000-170815- MESOSCALE DISCUSSION 1721 NWS STORM PREDICTION CENTER NORMAN OK 0218 AM CDT SAT JUL 17 2004 AREAS AFFECTED...SERN AR / NERN LA / MS CONCERNING...SEVERE THUNDERSTORM WATCH 652... VALID 170718Z - 170815Z ALTHOUGH THUNDERSTORMS CONTINUE ACROSS THE NRN HALF OF WW...SEVERE THREAT OVER MUCH OF WW HAS DECREASED. WW WILL BE ALLOWED TO EXPIRE AT 17/08Z. LATEST RADAR IMAGERY SHOWS STRONGEST STORMS ACROSS SERN AR ATTM...WITHIN AXIS OF MORE UNSTABLE AIR WHICH EXTENDS SWD INTO LA / FAR SWRN MS. MORE STABLE AIRMASS -- AND THUS WEAKER CONVECTION -- IS INDICATED ACROSS THE MS RIVER INTO W CENTRAL MS...WHERE EARLIER CONVECTION OCCURRED. ALTHOUGH SUFFICIENT INSTABILITY EXISTS ACROSS SERN AR / NERN LA AND SWRN MS -- ROUGHLY THE WRN HALF OF WW...DEEP-LAYER WIND FIELD IS SOMEWHAT WEAK -- PARTICULARLY AT MID-LEVELS WHERE ONLY 15 TO 20 KT FLOW IS INDICATED. THIS WOULD SUGGEST THAT LARGE-SCALE CONDITIONS ARE GENERALLY UNFAVORABLE FOR ANY MORE THAN ISOLATED / MARGINALLY-SEVERE STORMS. IF AN ORGANIZED COLD POOL -- AND AN ASSOCIATED LINE OF STORMS ALONG LEADING EDGE -- COULD EVOLVE FROM STORMS OVER SERN AR ATTM...THREAT FOR GUSTY / MARGINALLY SEVERE WIND GUSTS COULD INCREASE SOMEWHAT. WE WILL CONTINUE TO MONITOR THIS REGION FOR ANY MESOSCALE INDICATIONS OF AN INCREASING SEVERE THREAT...BUT ATTM NEW WW IS NOT EXPECTED AFTER THE 17/08Z EXPIRATION OF WW 652. ..GOSS.. 07/17/2004 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...JAN...LIX...LZK...LCH...SHV... 34239179 33529110 31439017 30979098 31169190 32469267 33839262
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 16, 9:18 PM CDT | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 14 more | 87 min |
| Jul 16, 9:45 PM CDT | Severe Thunderstorm Watch | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 17 more | 5 hr |
| Jul 17, 6:25 PM CDT | Mesoscale Discussion | SPC | Bienville, Caldwell, De Soto, Grant, Jackson, LaSalle and 6 more | 2 hr |
Nearby
Mesoscale Discussions in Louisiana, 2004Mesoscale Discussions in Mississippi, 2004Mesoscale Discussions in Arkansas, 2004Every mesoscale discussion in 2004
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.