Severe Weather Thread: March 25 - March 28

[Thundersnow12]

[tornadotony]

Tomorrow looks like an interesting case. You're going to have quite an unstable atmosphere with lots of moisture and shear, with good low-level shear along the warm front. What's particularly interesting is that the storm motion will be parallel to the front, a situation which, in the south, has historically led to training tornadic supercells.

[tornadotony]

00z SPC WRF has an intense supercell outbreak from 21z to about 09z across MS/AL/GA tomorrow...

[thewxmann]

Tomorrow's defin one of the more interesting days this year thus far. As I mentioned in my earlier post, the severity and location of the event will hinge a lot on latitude of frontal zone and edge of capping inversion. 0Z NAM paints a much more volatile setup than previous runs with more moisture, more backed winds, and stronger windfields aloft.

Preliminarily it does look like NE AL/NW GA may be under the greatest gun... we'll see how morning/early aftn convection plays out. A secondary zone of development may ensue in the MEG area. One important thing to note - the risk area is in the right-entrance region of one upper jet and the left exit region of another, an area favored for uplift. That may be enough for surface-based development in the warm sector.

[SmokeEater]

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1253 AM CDT SAT MAR 26 2011

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS MID-SOUTH/LOWER MS

VALLEY REGIONS TO AL/GA...

...SYNOPSIS...

IN MID-UPPER LEVELS...SPLIT-FLOW PATTERN FCST TO CONTINUE ACROSS

CENTRAL/N-CENTRAL NORTH AMERICA...LEAVING MUCH OF CONUS IN BROAD

BELT OF NEARLY ZONAL FLOW. MID-UPPER LOW...NOW EVIDENT IN MOISTURE

CHANNEL IMAGERY OFFSHORE PAC NW -- IS FCST TO DEAMPLIFY TO OPEN-WAVE

TROUGH AND BECOME NEGATIVELY TILTED...WHILE MOVING INLAND WA/ORE.

SERN LOBE OF THIS PERTURBATION MAY REACH 4-CORNERS REGION BY END OF

PERIOD. MEANWHILE...SHORTWAVE TROUGH NOW CROSSING PORTIONS

CENTRAL/SRN ROCKIES IS FCST TO MOVE EWD ACROSS LOWER MO VALLEY

REGION TO LOWER OH VALLEY...AMPLIFYING AS IT ENTERS CONFLUENT FLOW

ASSOCIATED WITH CYCLONE OVER CANADIAN MARITIMES.

AT SFC...LOW NOW OVER SRN OK IS EXPECTED TO DEEPEN SOMEWHAT EARLY IN

PERIOD...AS SRN FRINGE OF MID-UPPER WAVE APCHS. FRONTAL ZONE -- NOW

EXTENDING FROM THAT LOW ESEWD ACROSS ARKLATEX REGION TO CENTRAL MS

-- IS FCST TO SHARPEN PARTIALLY FROM WEAK NONCONVECTIVE

FRONTOGENESIS...BUT MAINLY VIA REINFORCEMENT OF BAROCLINICITY BY

PRECIP TO ITS N. SFC LOW IS EXPECTED TO TRACK EWD ALONG FRONT TO

NERN LA/SERN AR/W-CENTRAL MS AREA BY 27/00Z...WHILE FRONT GENERALLY

LIFTS NWD ACROSS FOREGOING PORTIONS NRN MS AND CENTRAL/NRN AL.

TRAILING COLD FRONT BY THEN SHOULD EXTEND ACROSS NWRN LA...E TX AND

S-CENTRAL TX. BY END OF PERIOD...COLD FRONT SHOULD REACH

MIDDLE-UPPER TX COASTAL PLAIN AND CENTRAL MS...WITH LOW OVER

N-CENTRAL/NWRN GA.

...MID-SOUTH/LOWER MS VALLEY REGIONS TO AL/GA...

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.

...SERN KS/NERN OK TO WRN OZARK REGION...

ELEVATED CONVECTIVE REGIME AND RELATED HAIL POTENTIAL MAY CARRY OVER

FROM PREVIOUS DAY AND SHIFT EWD ACROSS THIS REGION...WITH HAIL BEING

POSSIBLE. LAPSE RATES AND BUOYANCY EACH SHOULD BE FAVORABLE DUE TO

COMBINATION OF RELATIVELY COLD AIR ALOFT AND NWRN LIMB OF LOW LEVEL

WARM/MOIST ADVECTION REGIME...CONTRIBUTING TO MUCAPE 1000-1500 J/KG.

WITH 50-60 KT EFFECTIVE SHEAR...TSTMS MAY BE SUFFICIENTLY ORGANIZED

FOR HAIL THREAT.

..EDWARDS/DEAN.. 03/26/2011

[Stebo]

Tomorrow's defin one of the more interesting days this year thus far. As I mentioned in my earlier post, the severity and location of the event will hinge a lot on latitude of frontal zone and edge of capping inversion. 0Z NAM paints a much more volatile setup than previous runs with more moisture, more backed winds, and stronger windfields aloft.

Preliminarily it does look like NE AL/NW GA may be under the greatest gun... we'll see how morning/early aftn convection plays out. A secondary zone of development may ensue in the MEG area. One important thing to note - the risk area is in the right-entrance region of one upper jet and the left exit region of another, an area favored for uplift. That may be enough for surface-based development in the warm sector.

I'd agree that warm front will be pretty good, though I think the Western end of it stalls across the MS/AL border with TN tomorrow, could be action from Huntsville to Tupelo maybe as far West Northwest as Memphis.

[Thundersnow12]

nicely done write up by Roger, best three words of it are "vorticity-rich environment" lol

[David Reimer]

I'm going to be going nuts with the social media today. Here's a graphic representing today's risk from the 06Z outlook.

[ksstormhunter]

Here is my latest threat areas for severe weather for the next 12 hours. Seeing the strongest instability across the N. MS through Central Alabama areas. Seeing potential for 70-80KT winds and hail running about 1.5" possible. Right now the most prime area Greenwood to Greenville to Louisville, MS to Tuscaloosa, AL areas. Some of the shear and severe wx indices indicated potential for F1 type tornado possible. Any thoughts for these areas. Severe weather specifics are at http://smartwxmodel.net/severe.pdf

[SmokeEater]

Not as bullish as the overnight outlook.

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0755 AM CDT SAT MAR 26 2011

VALID 261300Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE LWR MS VLY

EWD INTO AL/GA...

...SYNOPSIS...

LARGELY ZONAL FLOW WILL PREVAIL ACROSS THE SRN TWO-THIRDS OF THE

NATION THROUGH SUN...SOUTH OF NEARLY STATIC OMEGA BLOCK PATTERN

ANCHORED BY UPR HIGH OVER NRN SK/MB. IN THE ZONAL JET...IMPULSE NOW

OVER THE CNTRL HI PLNS SHOULD REACH MO BY THIS EVE. THE FEATURE

LIKELY WILL DEAMPLIFY AS IT CONTINUES E INTO CONFLUENT FLOW OVER THE

OH VLY EARLY SUN. ELSEWHERE...DIFFLUENT NEG TILT TROUGH NOW ALONG

THE W CST SHOULD PROGRESS E INTO THE GRT BASIN/SRN RCKYS BY 12Z SUN.

AHEAD OF THIS FEATURE...SUBTROPICAL JET NOW OVER SRN/CNTRL TX MAY

EDGE SLIGHTLY ENE INTO LA AND THE LWR MS VLY.

AT LWR LVLS...LOW NOW OVER SRN OK EXPECTED TO BE SHUNTED ESE ALONG

THE RED RVR TODAY BY SPRAWLING SFC HIGH EXTENDING S FROM MB/WRN ONT.

THE LOW SHOULD REACH THE ARKLATEX BY THIS EVE...BEFORE CONTINUING E

OR ENE INTO N GA EARLY SUN. FRONT EXTENDING E FROM THE LOW MAY MIX

OR EDGE A BIT NWD ACROSS SRN AR AND PARTS OF MS... AL...AND GA LATER

TODAY/TONIGHT...BUT NO WHOLESALE NWD MOVEMENT APPEARS LIKELY. THIS

BOUNDARY...AND PARTS OF THE WARM SECTOR TO ITS S AND SE...SHOULD

SERVE AS THE MAIN FOCUS FOR STRONG/SVR STORMS THROUGH THE PERIOD.

...SRN/ERN AR AND NRN LA EWD INTO AL/GA/SC...

AFOREMENTIONED WARM/STNRY FRONT WILL BE ALIGNED ROUGHLY PARALLEL TO

40-50 KT DEEP W TO WNWLY SHEAR TODAY AS SFC HEATING AND CONTINUED

MOISTURE INFLOW /WITH PW UP TO 1.25 INCHES/ DESTABILIZE REGION.

THIS SETUP SHOULD PROVE SUPPORTIVE OF SVR STORM

DEVELOPMENT...INCLUDING SOME SFC-BASED SUPERCELLS...DURING THE

MIDDAY THROUGH EARLY EVE. STORMS ALSO MAY FORM S OF FRONT...

ESPECIALLY IN AL AND GA...WHERE WSWLY LOW-LVL FLOW WILL IMPINGE ON

SHALLOWER FRONTAL REMNANT OVER REGION.

STEEP MID LVL LAPSE RATES/EML PLUME AND RELATIVELY COOL PROFILES

WILL BE FAVORABLE FOR LARGE HAIL...ESPECIALLY IN WRN HALF OF SLIGHT

RISK. AND...GIVEN POTENTIAL FOR STORMS TO REMAIN WITHIN ZONE OF

ENHANCED LOW-LVL SHEAR NEAR BOUNDARY....POTENTIAL ALSO WILL EXIST

FOR TORNADOES.

THERE REMAINS UNCERTAINTY ATTM REGARDING AREA OF GREATEST LOW-LVL

ASCENT AND HEATING ALONG AND S OF THE WARM/STATIONARY FRONT.

SATELLITE/MODEL FCSTS SUGGEST THAT LARGE-SCALE FORCING FOR ASCENT

NEAR THE BOUNDARY WILL REMAIN MODEST. BUT COMBINATION OF DIURNAL

HEATING AND CONFLUENT LOW-LVL FLOW SHOULD BE SUFFICIENT TO INITIATE

STORMS LATER TODAY. BY EVE...CONVERGENCE ALSO SHOULD INCREASE ALONG

THAT PORTION OF THE BOUNDARY THAT WILL ACCELERATE SE AS A COLD FRONT

IN WAKE OF SFC WAVE. THIS SHOULD FOSTER ADDITIONAL STORM

DEVELOPMENT OVER SRN AR/NRN LA AND MS. SOME OF THIS ACTIVITY COULD

MOVE/DEVELOP E INTO GA AND POSSIBLY WRN SC BY EARLY SUN...WITH AT

LEAST A LIMITED THREAT FOR SVR.

...SE KS/NE OK TO NRN/WRN OZARKS...

SCTD ELEVATED STORMS AND RELATED HAIL POTENTIAL LIKELY WILL

PERSIST/SPREAD E ACROSS THE SE KS/SRN MO/NRN AR REGION TODAY...TIED

TO ASCENT/ELEVATED MOISTURE INFLOW WITH IMPULSE MOVING E FROM THE

CNTRL HI PLNS. MUCAPE OF 750-1000 J/KG... 50-60 KT CLOUD-LAYER

SHEAR...AND COOL PROFILES SUGGEST THAT SOME OF THE STORMS COULD

YIELD MARGINALLY SVR HAIL. THE POTENTIAL SHOULD LESSEN THIS EVE AS

UPR SYSTEM SHEARS E INTO THE OH VLY.

..CORFIDI/STOPPKOTTE.. 03/26/2011

[janetjanet998]

NAM is showng more helicity now as it doesn't veer winds quite as much...400-500 over MS/AL by 00z

RUC also hinting at the same thing

[janetjanet998]

looking at models and current obs..i see no reason why a moderate risk will not be issued in the next outlook in central MS/AL

[janetjanet998]

MESOSCALE DISCUSSION 0275

NWS STORM PREDICTION CENTER NORMAN OK

1021 AM CDT SAT MAR 26 2011

AREAS AFFECTED...NE MS...CNTRL/NRN AL

CONCERNING...OUTLOOK UPGRADE

VALID 261521Z - 261615Z

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

[David Reimer]

The 14Z RUC is suggesting an ominous picture for areas NE of Jackson, MS by late afternoon...

[Thundersnow12]

I haven't looked at the 14z RUC but the 12z RUC is showing quite a bit more 0-1 SRH than the 12z NAM.

[David Reimer]

While I can't post the NWSChat logs in here, Birmingham and the SPC are now saying this has a lot of similarity to the Palm Sunday Tornado Outbreak back in March, 1994 and are growing very concerned. This is reflected in their new AFD. Today definitely has the potential to be a red-letter day.

AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BIRMINGHAM AL 1039 AM CDT SAT MAR 26 2011 .UPDATE...MORNING/MESOSCALE UPDATE. && .DISCUSSION... SEVERE/TORNADO THREAT CONTINUES TO SLOWLY EVOLVE...AND INCREASING TO MODERATE RISK PER SPC MCD...THIS MORNING. 17Z SPECIAL RELEASE SCHEDULED TO ASSIST IN EVALUATION OF THE THREAT. ONGOING PRECIPITATION ACROSS THE TENNESSEE VALLEY IS HELPING TO BETTER DEFINE THE THREAT AREA THIS MORNING. QUASI-STATIONARY BOUNDARY...WITH CONCENTRATED AREA OF MOISTURE CONVERGENCE AND LIFT... BECOMING A BIT ENHANCED. STRONG DEWPOINT DISCONTINUITY...WITH ANNISTON DP JUMPING UP 10 DEGREES BETWEEN 13Z AND 14Z...BUT HAS DROPPED AGAIN AS COLD POOL UP NORTH NUDGES SOUTHWARD. REGARDLESS... MID 60S DEWPOINTS TO THE SOUTH OF THE AREA...WITH UPPER 40S TO THE NORTH. IN THE WARM SECTOR...AS TEMPERATURES CLIMB INTO THE MID AND UPPER 70S...EXPECT SURFACE BASED INSTABILITY TO OVERCOME SLIGHT CAP...AND WITH SUFFICIENT SHEAR...CONFIDENCE IN TORNADIC DEVELOPMENT IS ON THE INCREASE. FOCUS OF GREATEST CONCERN WILL BE ALONG AND SOUTH OF THE BOUNDARY...RIGHT ACROSS THE HEART OF CENTRAL ALABAMA. WATER VAPOR SAT SHOW LAYER OF DRY AIR ADVECTING IN OVER THE TOP OF THIS LAYER AS WELL. CONCERN WILL BE FOR ANY CELLS THAT FORM NEAR/ALONG THE BOUNDARY...AND POTENTIALLY RIDE ALONG IT FOR SOME TIME. SET UP HAS SIMILARITIES TO MARCH 94...WHICH WAS NOT A GOOD DAY. A BRIEF LITANY OF RUC13 PARAMETERS OF CONCERN...SURFACE BASED LI'S LESS THAN -6...EHI'S APPROACHING 5 IN SOME AREAS...HELICITY > 200 M2/S2...AND CAPE > 1500 J/KG...ALL POINT TO A RIPE ENVIRONMENT. ONCE WE HAVE CONVECTIVE INITIATION...LOOKS LIKE THE MOST SIGNIFICANT THREAT WILL CONTINUE INTO THE EVENING HOURS. ONLY MINOR TWEAKS TO FORECAST PACKAGE NEEDED...MAINLY TO REFLECT COLD POOLING UP NORTH...AS WELL AS THE ADDITION OF TORNADO/HAIL/WIND VERBIAGE IN THE THREAT AREA.

[Jim Martin]

845

ACUS01 KWNS 261614

SWODY1

SPC AC 261612

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1112 AM CDT SAT MAR 26 2011

VALID 261630Z - 271200Z

...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

[janetjanet998]

there is no rule as to where to post stuff, and in an outbreak there may be overlap between subforums. There really can't be a "cut off" because every outbreak is different. For example, An outbreak that starts in TX/LA and moves all the way to the east coast will of course start in the central forum...while an outbreak that starts in eastern AL with 90% of it into GA or SC will likley only have a thread in the SE subforum

here is the thread for the SE forum, traditionary once storms cross into GA the posting go there no matter what.

http://www.americanwx.com/bb/index.php/topic/15857-severe-weather-threat-saturday-326/

[janetjanet998]

why no hatching for tornadoes? error?

[Thundersnow12]

why no hatching for tornadoes? error?

I was wondering that as well, they even mention strong tornadoes in the outlook wording.

[janetjanet998]

storm already developing in MS

MESOSCALE DISCUSSION 0276

NWS STORM PREDICTION CENTER NORMAN OK

1125 AM CDT SAT MAR 26 2011

AREAS AFFECTED...ECNTRL/NERN MS...CNTRL/NRN AL...WCNTRL GA

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 261625Z - 261800Z

BAND OF CUMULUS OVER CNTRL MS APPEARS TO BE DEEPENING WITHIN A ZONE

OF WEAKLY CONFLUENT LOW-LEVEL FLOW AND WHERE THE BOUNDARY LAYER WAS

HEATING INTO THE MID-UPPER 70S. THIS MAY BE THE START OF AN ACTIVE

AFTERNOON/EVENING AS THE STORMS GRADUALLY EVOLVE ENE INTO CNTRL/NRN

AL AND WCNTRL GA.

THE DEEP LAYER FLOW IS GENERALLY UNIDIRECTIONAL WSWLY...THOUGH SPEED

SHEAR IS MORE THAN SUFFICIENT FOR SUPERCELLS. MID-LEVEL LAPSE RATES

IN EXCESS OF 7 DEG C PER KM AND MAGNITUDE OF VERTICAL SHEAR WILL

YIELD VERY LARGE HAIL WITH ANY STORM. AS STORMS APPROACH THE BACKED

LOW-LEVEL FLOW IN VICINITY OF THE WARM/WEDGE FRONT ACROSS CNTRL/NRN

AL AND WCNTRL GA...CONCERN IS FOR DISCRETE SUPERCELLS TO PRODUCE A

FEW TORNADOES.

ALTHOUGH FIRST SIGNS OF INITIATION ARE LIMITED TO MS...EXPECT THAT

ADDITIONAL DISCRETE STORMS WILL FORM IN THE WARM SECTOR ACROSS

CNTRL/SRN AL AND WCNTRL GA THROUGH THE AFTERNOON.

[southmdwatcher]

Is there a forecaster at the SPC by the name of Richard Thompson? If so he is on the chat attached with Stormscape/Mike Phelps and is saying that he really is not bullish on a tornado outbreak today, some parameters missing aside from low level lift.

[janetjanet998]

Is there a forecaster at the SPC by the name of Richard Thompson? If so he is on the chat attached with Stormscape/Mike Phelps and is saying that he really is not bullish on a tornado outbreak today, some parameters missing aside from low level lift.

Yes in fact he often posts here....or did at least at eastern as Chompson

[janetjanet998]

WWUS30 KWNS 261712

SAW2

SPC AWW 261712

WW 62 TORNADO AL GA 261715Z - 270100Z

AXIS..85 STATUTE MILES NORTH AND SOUTH OF LINE..

65NE MGR/MOULTRIE GA/ - 40W TCL/TUSCALOOSA AL/

..AVIATION COORDS.. 75NM N/S /29WNW AMG - 19SSE IGB/

HAIL SURFACE AND ALOFT..3 INCHES. WIND GUSTS..60 KNOTS.

MAX TOPS TO 500. MEAN STORM MOTION VECTOR 24030.

LAT...LON 30518301 31988830 34458830 32978301

THIS IS AN APPROXIMATION TO THE WATCH AREA. FOR A

COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS

FOR WOU2.

[janetjanet998]

the front has sagged south and it bisecting the BHM metro..temps down form 71 to 58..winds have turned east

not a good place to be..the front will wobble around and any cell turning east along it will maximize the shear

[janetjanet998]

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 62

NWS STORM PREDICTION CENTER NORMAN OK

115 PM EDT SAT MAR 26 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF

LARGE PART OF ALABAMA

A LARGE PART OF WESTERN GEORGIA

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 115 PM UNTIL

900 PM EDT.

TORNADOES...HAIL TO 3 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.

DISCUSSION...THUNDERSTORMS WILL INCREASE IN NUMBER AND INTENSITY

ACROSS THE WATCH AREA AS AIR MASS HAS BECOME MDTLY UNSTABLE IN A

FAVORABLE SHEAR ENVIRONMENT FOR SUPERCELL DEVELOPMENT. SEVERE

THUNDERSTORMS ARE LIKELY INCLUDING TORNADIC SUPERCELLS THRU THE

AFTERNOON AS STORMS DEVELOP ALONG AND S OF E/W FRONTAL ZONE THRU NRN

AL INTO CENTRAL GA. THERE IS THE POSSIBILITY OF A STRONG TORNADO

BY LATER THIS AFTERNOON.

[janetjanet998]

very dangerous set up here as storm motions will take the storms right along the WF...(rather than moving them northeast over it)

[Thundersnow12]

Is there a forecaster at the SPC by the name of Richard Thompson? If so he is on the chat attached with Stormscape/Mike Phelps and is saying that he really is not bullish on a tornado outbreak today, some parameters missing aside from low level lift.

Rich Thompon is the best forecaster out there IMO with Roger Edwards a close 2nd.

[janetjanet998]

mulitple lines of developing discrete storms and developing supercells: one on the MS/AL state line another central AL, another eastern AL(sites on SW ATL metro) and yet another in SW GA

[southmdwatcher]

Rich Thompon is the best forecaster out there IMO with Roger Edwards a close 2nd.

Thanks, his dialogue over there for just a couple of minutes was very informative. He said there would be some tornadoes but the parameters just didn't look right for any more than an isolated strong tornado.. I hope this information is not inappropriate to pass along since it was at a .com/chaser site?