Note: This will be a running blog post where updates are added throughout the day. Please use the timestamps on the left hand side of the update, which will be in CDT.
Final Note: Here’s all the images we ended up posting today. The time (UTC) is the title name.
5:15 PM: After several hours of activity in Alabama a W. Georgia we’re generally in a lull now (SW GA being the exception). I’ve updated the gallery below with all the images taken throughout this afternoon. Here’s a satellite image taken around 5 PM showing where we’re watching for new developing. An expansive CU field is obvious from LA/AR all the way east to AL. We’re just waiting for the storms to pop. All parameters are favorable for significant severe weather including supercells.
12:50 PM: So it begins… We’ll be running with a gallery type system from this point out so we can speed up the process. Stay tuned!
1:30 AM: SPC indicates a Tornado Watch will be issued for MS/AL/GA shortly.
1:25 AM: The new SPC outlook is out and has increased the tornado probabilities across NE MS and AL. Those areas now have a 15% chance of seeing a tornado within 25 miles of any given point. Here’s the new outlook and graphic.
...THERE IS A MDT RISK OF SVR TSTMS PARTS OF CENTRAL AND NORTH AL AND NORTHEAST MS... ...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE LWR MS VLY EWD INTO AL/GA/SC... ..SYNOPSIS S/WV TROUGH CENTRAL PLAINS EMBEDDED IN FAST ZONAL FLOW WILL CONTINUE EAST ACROSS MS INTO TN VALLEY BY THIS EVENING. FROM THE SURFACE LOW OVER SERN OK A NEARLY STATIONARY FRONTAL ZONE EXTENDS EWD ACROSS SRN AR AND NRN GULF STATES JUST TO N OF BHM TO NEAR ATL. COLD FRONT TRAILS SWWD FROM SURFACE LOW ACROSS NWRN INTO SWRN TX. THE WARM SECTOR OVER CENTRAL GULF STATES FROM ERN TX TO AL AND SPREADING EWD INTO SRN GA S OF FRONTAL ZONE IS BECOMING VERY FAVORABLE FOR DEVELOPMENT OF SEVERE THUNDERSTORMS INCLUDING SUPERCELLS THIS AFTERNOON. IN ADDITION TO THE E/W FRONTAL ZONE ACROSS NRN GULF STATES PROVIDING A FOCUS FOR SURFACE BASED CONVECTIVE INITIATION THE WARM SECTOR ACROSS CENTRAL AL/MS THROUGH HEATING WILL LEAD TO POTENTIAL OF DISCRETE SEVERE THUNDERSTORMS AS CINH DISSIPATES BY MID AFTERNOON. STEEP MID LVL LAPSE RATES AND RELATIVELY COOL PROFILES WILL SUPPORT MDT INSTABILITY WITH MLCAPES AOA 2000 J/KG FROM LWR MS VLY TO CENTRAL AL THIS AFTERNOON. ..PARTS OF CENTRAL/NRN AL INTO NRN MS WITH 30-40KT LOW LEVEL WSWLY FLOW VEERING SHEAR PROFILES WILL BE QUITE FAVORABLE FOR SUPERCELLS INCLUDING TORNADOS AND VERY LARGE HAIL. IT NOW APPEARS THAT SURFACE BASED INITIATION WILL BE ABLE TO OCCUR BY MID AFTERNOON IN THE WARM SECTOR WHICH INCREASES THE THREAT OF LONG-LIVED SUPERCELLS AND ASSOCIATED TORNADOES. THE AREA OF GREATEST RISK OF THIS OCCURRENCE HAS BEEN UPGRADED TO A MDT RISK...ALTHOUGH THE GREATER POTENTIAL COULD EXTEND EVEN INTO WRN GA IF SUFFICIENT INSTABILITY DEVELOPS . THERE IS THE THREAT OF STRONG TORNADOES WITH ANY SUSTAINED SUPERCELLS. ..SRN/ERN AR/NRN LA EWD ACROSS AL/GA AND SC FURTHER W THE INITIALLY STRONGER CAP THROUGH THE PROCESS OF HEATING AND ASCENT ALONG THE COLD FRONT WILL WEAKEN BY LATER THIS AFTERNOON TO ALLOW SEVERE THUNDERSTORM DEVELOPMENT FROM SRN AR INTO NRN LA. WHILE LOW LEVEL SHEAR WILL NOT BE QUITE AS FAVORABLE AS FURTHER E...MLCAPES IN EXCESS OF 2000 J/KG...BRN SHEAR OF 40-50KT ALONG WITH THE VERY STEEP MID LEVEL LAPSE RATES WILL ALSO SUPPORT SUPERCELLS. IN ADDITION TO THE VERY LARGE HAIL THREAT...A FEW TORNADOES ARE ALSO LIKELY. OVERNIGHT THE STORMS THAT DEVELOP OVER AL/MS THIS AFTERNOON WILL HAVE SPREAD EWD ACROSS GA WITH AT LEAST A THREAT OF LARGE HAIL AND DAMAGING WINDS IN PARTS OF WRN SC WHERE AIR MASS WILL BE MORE MARGINALLY UNSTABLE. MEANWHILE THE COLD FRONTAL INITIATED ACTIVITY WILL MAINTAIN A SEVERE THREAT INCLUDING SUPERCELLS AND ISOLATED TORNADOES EWD ACROSS CENTRAL MS/AL AND POSSIBLY INTO SRN GA BY EARLY SUN. ..HALES/ROGERS.. 03/26/2011
1:00 AM: SPC and several NWS offices are now using the Palm Sunday Tornado Outbreak back in March of 1994 as an analog to today’s event. Today has the potential to produce devastating tornadoes across MS/AL. Those in mobile homes should spend the day at a more reliable structure, such as a church, city building, or a friend’s house. Today is the day where you could get a lot of fatalities if a tornado goes through a mobile home park.
10:25 AM: The Storm Prediction Center is upgrading their convective outlook to the “Moderate’ level due to an increased tornado threat this afternoon and evening. Reference the graphic and text below.
1630 UTC DAY 1 CONVECTIVE OUTLOOK WILL BE UPGRADING PARTS OF NE MS AND CNTRL/NRN AL TO A MODERATE RISK. CATEGORICAL RISK WILL BE DRIVEN BY 15 PERCENT TORNADO PROBABILITIES. REFER TO GRAPHIC FOR DETAILED AREA. DETAILS WILL BE FORTHCOMING IN SWODY1 BY 1630 UTC.
1:45 AM: The NSSL (National Severe Storms Lab) high resolution WRF shows an extremely dangerous situation across Mississippi and Alabama by 8 PM tonight, with the model actually showing a tornadic supercell with a hook in MS with all the parameters off the chart. Another cell is over Central Alabama at this point. This won’t play out exactly how it is shown on the graphic below, but it is indicative of the dangerous potential today holds.
1:05 AM: The Storm Prediction Center has issued a high-end standard risk of severe weather today from SE Arkansas all the way into Western Georgia. Here’s the discussion and associated risk graphic.
GREATEST POTENTIAL FOR SFC-BASED SVR TSTM DEVELOPMENT...INCLUDING SUPERCELLS WITH TORNADOES...LARGE HAIL AND DAMAGING GUSTS...WILL BE DURING MIDDAY THROUGH EARLY EVENING ACROSS CORRIDOR OF MAX PROBABILITIES...ALONG AND S OF IMMEDIATE SFC FRONTAL ZONE. FRONT SHOULD BE ALIGNED CLOSE TO MEAN WIND VECTOR...IN ENVIRONMENT CHARACTERIZED BY INCREASING DIURNAL INSTABILITY...FAVORABLE DEEP-LAYER SHEAR...AND ENHANCED HODOGRAPH SIZE/SRH ALONG BOUNDARY. AS SUCH...ANY RELATIVELY DISCRETE STORMS THAT CAN INTERACT WITH FRONT MAY SPEND A LONG TIME IN ITS VORTICITY-RICH ENVIRONMENT...WITH ENHANCED TORNADO RISK. MAIN UNCERTAINTY IS IN POSITION OF WARM/STATIONARY FRONT E OF LOW. SOME LATITUDINAL MARGIN FOR ERROR IS NEEDED IN SVR PROBABILITIES ATTM GIVEN WIDE VARIATION IN PROGGED TIMING/COVERAGE OF PRECIP N OF FRONT...IN TURN INFLUENCING EFFECTIVE BOUNDARY LOCATION DURING PEAK CONVECTIVE PERIOD. SCATTERED-NUMEROUS TSTMS IN CLUSTERS ARE PROBABLE ACROSS PORTIONS AR AND MID-SOUTH DURING MORNING AND AFTERNOON...CARRYING OVER FROM BEFORE 26/12Z. ADDITIONAL ACTIVITY MAY FORM THROUGHOUT PERIOD N OF FRONT AS ELEVATED WAA/MOISTURE TRANSPORT REGIME SHIFTS EWD ACROSS SRN APPALACHIANS. S OF FRONTAL ZONE...IN ABSENCE OF APPRECIABLE MID-UPPER PERTURBATIONS...CONVECTIVE INITIATION AND COVERAGE DEPEND ON MESOSCALE SUBTLETIES AND CAPPING ISSUES NOT NECESSARILY WELL FCST BY SYNOPTIC MODELS. VERTICAL SHEAR PROFILES CERTAINLY WILL BE FAVORABLE FOR SUPERCELLS...HOWEVER...SO ANY CONVECTION THAT CAN DEVELOP OVER CENTRAL/SRN PORTIONS AL...WRN GA AND MS S OF FRONT WILL POSE TORNADO/HAIL/WIND THREAT AS WELL. CENTRAL/SRN AL MAY REPRESENT RELATIVE MAX OF POTENTIAL S OF FRONT...SINCE IT WILL RESIDE E OF STRONGEST ELEVATED MIXED LAYER AIR...WHERE CINH WILL BE WEAKENED MOST READILY VIA AFTERNOON HEATING AND CONVECTIVE PROCESSES. SVR PROBABILITIES SHOULD LESSEN WITH TIME AND EWD EXTENT ACROSS GA OVERNIGHT AS INSTABILITY WEAKENS...BUT NOT DISAPPEAR ALTOGETHER. UNCERTAINTIES REGARDING MORE PRECISE FRONTAL POSITION...BAND COVERAGE S OF FRONT...PRECLUDE PROBABILITIES SUPPORTING CATEGORICAL MDT RISK ATTM. HOWEVER...UPPER-END SLGT EASILY MAY BE UPGRADED ONCE SOME OF THESE UNCERTAINTIES ARE BETTER RESOLVED.