Mesoscale Discussion 557

Issued

Apr 24, 2011, 6:23 PM CDT (23:23 UTC)

Expired

Apr 24, 2011, 8:30 PM CDT

In force

2 hr

Issued by

the Storm Prediction Center

The Little Rock radar (KLZK), 71 km from the middle of the area, began a volume at 23:23 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.

927 
ACUS11 KWNS 242323
SWOMCD
SPC MCD 242323 
TNZ000-MOZ000-ARZ000-OKZ000-TXZ000-250130-

MESOSCALE DISCUSSION 0557
NWS STORM PREDICTION CENTER NORMAN OK
0623 PM CDT SUN APR 24 2011

AREAS AFFECTED...PORTIONS WRN/NRN AR...SERN OK...MO BOOT-HEEL...NWRN
TN.

CONCERNING...TORNADO WATCH 192...197...

VALID 242323Z - 250130Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 192...197...CONTINUES.

SVR TSTMS ARE EXPECTED TO MOVE EWD OUT OF NERN AR INTO MO BOOT-HEEL.
 COUNTIES MAY BE ADDED TO NERN PORTIONS WW 192 IN ADVANCE OF THAT
ACTIVITY.  MEANWHILE...SVR POTENTIAL FCST TO INCREASE ACROSS WRN
PORTIONS WW 192 AFTER SCHEDULED 00Z EXPIRATION.  ULTIMATELY...EITHER
NEW WW COULD BE REQUIRED ACROSS PORTIONS AR E OF WW 197...OR
COUNTIES ADDED TO WW 197...GIVEN INCREASING SVR THREAT FROM W-E THIS
EVENING.

SFC MESOANALYSIS SHOWS QUASISTATIONARY OUTFLOW BOUNDARY BETWEEN
BNA-BWG...ALIGNED WSWWD TO WWD ACROSS NRN TIER TN COUNTIES TO MO
BOOT-HEEL.  SVR TSTMS OVER NERN AR WILL CONTINUE MOVING ALONG AND N
OF THIS BOUNDARY...WHERE LOW-LEVEL SRH AND STORM-RELATIVE INFLOW
WILL BE ENHANCED.  ANOTHER OUTFLOW BOUNDARY EXTENDS SWWD FROM THAT
ACTIVITY ACROSS WHITE/PULASKI/SALINE COUNTIES AR...MOVING SEWD 5-10
KT BUT FCST TO DECELERATE TO QUASISTATIONARY IN NEXT COUPLE HOURS. 
THAT PORTION OF THIS BOUNDARY WWD ACROSS LEFLORE COUNTY OK ALREADY
HAS STALLED.  CORRESPONDING ZONE OF ENHANCED LOW-LEVEL VORTICITY/SRH
WILL ACT TO CONCENTRATE EMBEDDED/SUPERCELLULAR AND/OR LEADING-EDGE
QLCS TORNADO POTENTIAL ASSOCIATED WITH BAND OF SVR TSTMS NOW OVER
ERN OK.  ADDITIONAL DEVELOPMENT...PERHAPS INCLUDING SUPERCELLS...IS
POSSIBLE NEAR SFC LOW MOVING EWD FROM S-CENTRAL OK...AND WARM FRONT
EXTENDING TO ITS ENE ACROSS COAL/SRN PITTSBURG/LATIMER COUNTIES TO
INTERSECTION WITH OUTFLOW BOUNDARY OVER LEFLORE COUNTY.  VWP DATA
AND MODIFIED RUC SOUNDINGS INDICATE 0-1 KM SRH 300-500 J/KG JUST N
OF OUTFLOW BOUNDARY NEAR FSM...AND EFFECTIVE SHEAR MAGNITUDES 45-55
KT SWD OVER ADJACENT WARM SECTOR.  STRONGEST BUOYANCY WILL REMAIN S
OF BOUNDARY WITH MLCAPE IN 1500-2500 J/KG RANGE THROUGH AT LEAST
01Z.  HOWEVER...SFC-BASED EFFECTIVE INFLOW PARCELS ARE EVIDENT 10-20
NM N OF OUTFLOW BOUNDARY AND WARM FRONT.

..EDWARDS.. 04/24/2011

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

ATTN...WFO...PAH...MEG...LZK...SGF...SHV...TSA...FWD...OUN...

LAT...LON   33689457 33949685 34919579 35889329 36499276 36489017
            36468878 35608992 34759240 33689457

Mesoscale Discussions in Arkansas, 2011Mesoscale Discussions in Oklahoma, 2011Mesoscale Discussions in Tennessee, 2011Every mesoscale discussion in 2011

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.