Alert archive / Oklahoma / Mesoscale Discussions in 2004

Mesoscale Discussion 421

April 21, 200424 counties in Oklahoma

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2004, 7:51 PM CDT for 24 counties in Oklahoma. It was in force for 84 min.

The area

The outline as issued.

The facts

Issued
Apr 21, 2004, 7:51 PM CDT (00:51 UTC)
Expired
Apr 21, 2004, 9:15 PM CDT
In force
84 min
Issued by
the Storm Prediction Center
All 24 counties

Alfalfa County, OK, Blaine County, OK, Choctaw County, OK, Cleveland County, OK, Creek County, OK, Delaware County, OK, Dewey County, OK, Grant County, OK, Hughes County, OK, Kingfisher County, OK, Marshall County, OK, Mayes County, OK, McIntosh County, OK, Murray County, OK, Muskogee County, OK, Oklahoma County, OK, Okmulgee County, OK, Osage County, OK, Pawnee County, OK, Pontotoc County, OK, Pushmataha County, OK, Rogers County, OK, Tulsa County, OK, Wagoner County, OK

The radar

The Norman radar (KTLX), 38 km from the middle of the area, began a volume at 00:54 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.

The nearest sounding before it

Norman, OK (KOUN), launched 00:00Z, 0.9 hours before the alert went out and 46 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-pSkew-T log-p diagram, Norman, OK at 00:00Z on 2004-04-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 415 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Norman, OK at 00:00Z on 2004-04-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 120 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
415 J/kg
Mixed-layer CIN
-82 J/kg
Mixed-layer LCL
1340 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
120 m²/s²
0-3 km storm-relative helicity
357 m²/s²
Significant tornado parameter
0.4
Supercell composite
11.0

Open this sounding in Storm Lab

The text

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

448 
ACUS11 KWNS 220052
SWOMCD
SPC MCD 220051 
OKZ000-ARZ000-TXZ000-KSZ000-220215-

MESOSCALE DISCUSSION 0421
NWS STORM PREDICTION CENTER NORMAN OK
0751 PM CDT WED APR 21 2004

AREAS AFFECTED...OKLAHOMA

CONCERNING...SEVERE THUNDERSTORM WATCH 98...

VALID 220051Z - 220215Z

...TORNADO THREAT CONTINUES...ESPECIALLY ACROSS NORTHWEST AND
SOUTHEAST OKLAHOMA...AT LEAST UNTIL 02Z. AT 02Z...ANOTHER WW WILL
LIKELY BE NEEDED FOR PORTIONS OF NRN AND ERN OK.

SEVERE THUNDERSTORMS ARE MOVING EWD ACROSS NWRN OK WHERE ELY
BOUNDARY LAYER WINDS AT 20 KT ARE RESULTING IN SUFFICIENT LOW/MID
LEVEL SHEAR FOR SUPERCELLS AND POSSIBLY TORNADOES. ALSO THE LOW
LEVEL SELY WINDS HAVE INCREASED TO 20 KT ACROSS SERN OK AND
TORNADOES APPEAR TO BE A SLIGHTLY GREATER THREAT THAN
EARLIER...ESPECIALLY ALONG AND EAST OF THE STORMS THAT CURRENTLY
EXTEND FROM 45 W OF MLC TO 25 S ADM. DEEP LAYER SHEAR AROUND 50 KT
AND MUCAPES AROUND 1500 J/KG INDICATE A THREAT FOR 3/4 TO 2 INCH
SIZED HAIL IN THE MORE INTENSE STORMS.

DRIER AIR HAS SPREAD NWD ACROSS THE SWRN QUARTER OF THE WW WITH THE
THREAT OF STORMS OVER THIS PORTION OF THE STATE.

..IMY.. 04/22/2004

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

ATTN...WFO...OUN...SHV...TSA...FWD...DDC...AMA...

36959869 36869974 35979990 36029877 36779733 

33799475 33909707 35789719 35809999 37040002 36759704
36419459 

33999697 35189653 34939567 34209557 33939633

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 21, 7:06 PM CDTMesoscale DiscussionSPCAlfalfa, Beaver, Blaine, Dewey, Ellis, Harper and 3 more2 hr
Apr 21, 8:35 PM CDTSevere Thunderstorm WatchSPCAlfalfa, Blaine, Dewey, Ellis, Garfield, Grant and 9 more5 hr
Apr 21, 8:35 PM CDTTornado WatchSPCAtoka, Bryan, Choctaw, Coal, Haskell, Hughes and 6 more5 hr
Apr 21, 10:10 PM CDTMesoscale DiscussionSPCAdair, Cherokee, Craig, Creek, Delaware, Mayes and 8 more95 min
Apr 21, 10:26 PM CDTMesoscale DiscussionSPCAtoka, Bryan, Choctaw, Coal, Haskell, Hughes and 7 more64 min
Apr 21, 10:50 PM CDTSevere Thunderstorm WatchSPCAdair, Cherokee, Craig, Creek, Delaware, Haskell and 14 more5 hr
Apr 21, 10:56 PM CDTMesoscale DiscussionSPCAlfalfa, Garfield, Grant, Kay, Kingfisher, Logan and 2 more94 min
Apr 22, 1:43 AM CDTMesoscale DiscussionSPCAdair, Cherokee, Haskell, McIntosh, Mayes, Muskogee and 7 more92 min
Apr 22, 12:32 PM CDTMesoscale DiscussionSPCAdair, Atoka, Cherokee, Coal, Delaware, Haskell and 15 more88 min
Apr 22, 1:40 PM CDTTornado WatchSPCAdair, Atoka, Bryan, Carter, Cherokee, Choctaw and 33 more6 hr
Apr 22, 3:26 PM CDTMesoscale DiscussionSPCAdair, Atoka, Cherokee, Coal, Haskell, Hughes and 16 more64 min
Apr 22, 4:30 PM CDTTornado WatchSPCBryan, Love6 hr
Apr 22, 5:27 PM CDTMesoscale DiscussionSPCAdair, Atoka, Bryan, Choctaw, Coal, Craig and 23 more63 min
Apr 22, 6:23 PM CDTMesoscale DiscussionSPCAdair, Carter, Garvin, Hughes, LeFlore, McCurtain and 10 more67 min

Nearby

Mesoscale Discussions in Oklahoma, 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.