Severe Weather Threat. April 21st-25th, 2010 High Risk!

[Bunkertor]

[thetruesms]

Interesting that the tornado warning fun begins in Colorado today

[CrazyC83]

Interesting that the tornado warning fun begins in Colorado today

Not surprised though, as I thought the low center would have its own activity. It just started earlier than expected.

[srainhoutx]

Interesting that the tornado warning fun begins in Colorado today

Also interesting that CO, WY, and NE are getting bands of heavy snow in the deformation zone as well. Potent Spring Storm!

[CrazyC83]

New Day 2: upgrade to HIGH likely on Day 1

SPC AC 231729

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1229 PM CDT FRI APR 23 2010

VALID 241200Z - 251200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF AR...FAR EAST
TX...LA...MS...AL...TN...FAR SE MO...FAR SRN IL AND WRN KY...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS....UPPER MIDWEST...MS VALLEY...OH VALLEY...TN VALLEY...SRN
APPALACHIAN MTNS AND ERN GULF COAST STATES...

...TORNADO OUTBREAK POSSIBLE ACROSS PARTS OF THE OZARKS...THE LOWER
TO MID MS VALLEY AND TN VALLEY SATURDAY AND SATURDAY NIGHT...

...OZARKS/LOWER TO MID MS VALLEY/TN VALLEY...
A WELL-ORGANIZED UPPER-LEVEL SYSTEM WILL MOVE EWD ACROSS THE GREAT
PLAINS INTO THE MS VALLEY SATURDAY AS A 75 TO 90 KT MID-LEVEL JET
ROUNDS THE BASE OF THE UPPER-LEVEL TROUGH. AS HEIGHTS FALL ACROSS
THE LOWER MS VALLEY SATURDAY MORNING...MODEL FORECASTS QUICKLY
DEVELOP AN IMPRESSIVE 50 TO 60 KT LOW-LEVEL JET IN THE LOWER MS
VALLEY. A CLUSTER OF POTENTIALLY SEVERE THUNDERSTORMS SHOULD BE
ONGOING IN NE TX AT 12Z SATURDAY ON THE WRN EDGE OF THE LOW-LEVEL
JET. THE MODELS MOVE THIS CONVECTIVE CLUSTER EWD INTO NRN LA AND SRN
AR SATURDAY MORNING WITH OTHER STORMS DEVELOPING EWD ALONG A WARM
FRONT AND ACROSS THE WARM SECTOR IN THE TN VALLEY. VERY STRONG DEEP
LAYER SHEAR...MODERATE INSTABILITY AND IMPRESSIVE LOW-LEVEL SHEAR
PROFILES ALREADY IN PLACE SATURDAY MORNING SHOULD BE FAVORABLE FOR
SUPERCELLS AND TORNADOES AS THE MCS AND SEVERAL STORM CLUSTERS
ORGANIZE.

CONSIDERING THE SYNOPTIC SETUP...SEVERAL FACTORS APPEAR TO BE COMING
TOGETHER FOR A TORNADO OUTBREAK ACROSS THE REGION SATURDAY WITH A
WIDESPREAD SEVERE THREAT CONTINUING THROUGH SATURDAY EVENING. THE
KEY TO A TORNADO OUTBREAK SHOULD BE THE POSITION OF THE LOW-LEVEL
JET. THE GFS AND NAM SOLUTIONS VARY WITH THE GFS FOCUSING THE
LOW-LEVEL JET ACROSS NE LA AND NW MS SATURDAY MORNING WITH THE NAM
FOCUSING THE LOW-LEVEL JET FURTHER SOUTHEAST IN SCNTRL MS. AT THIS
POINT...HAVE TAKEN A COMPROMISE BETWEEN THE TWO SOLUTIONS BUT AM
FAVORING THE GFS SOLUTION WHICH IS SUGGESTING THE POTENTIAL FOR
TORNADOES WILL BE GREATEST ACROSS NRN LA...SRN/ERN AR AND WRN/NRN MS
SATURDAY MORNING THROUGH EARLY AFTERNOON. A POTENTIAL FOR TORNADIC
SUPERCELLS SHOULD ALSO EXIST EWD ALONG A WARM FRONT INTO NRN AL AND
SWD ACROSS THE WARM SECTOR ACROSS MS AND AL SATURDAY AFTERNOON. ANY
SUPERCELLS THAT DEVELOP ACROSS THE REGION SHOULD ALSO HAVE A THREAT
FOR LARGE HAIL AND WIND DAMAGE.

CONCERNING THE TORNADO OUTBREAK SCENARIO...THE THINKING IS THAT A
CLUSTER OF TORNADIC SUPERCELLS WILL ORGANIZE NEAR THE SABINE RIVER
IN FAR NE TX AROUND 12Z SATURDAY AND MOVE ENEWD ACROSS NRN LA INTO
ERN AR AND NWRN MS BY MIDDAY. THE GFS IS FORECASTING THE MCS TO BE
JUST AHEAD OF AND TO THE WEST OF THE MID-LEVEL JET CORE SUGGESTING
THE SETUP COULD BE FAVORABLE FOR STRONG TO VIOLENT TORNADOES AND A
LONG-TRACK TORNADO WILL BE POSSIBLE. AN OUTLOOK UPGRADE TO HIGH RISK
MAY BE NEEDED ACROSS PARTS OF THE REGION AS CONFIDENCE INCREASES
CONCERNING THE MODEL SOLUTIONS. ALTHOUGH THE BRUNT OF THE OUTBREAK
IS EXPECTED DURING THE MORNING AND EARLY AFTERNOON...SUPERCELLS AND
WELL-DEVELOPED LINE-SEGMENTS SHOULD BE CAPABLE OF PRODUCING
TORNADOES...LARGE HAIL AND WIND DAMAGE THROUGH SATURDAY EVENING.

...MID-MO VALLEY/UPPER MIDWEST...
A WELL-DEVELOPED UPPER-LEVEL LOW OVER THE CNTRL PLAINS WILL MOVE EWD
INTO THE MID-MO VALLEY SATURDAY AFTERNOON WHERE MODEL FORECASTS SHOW
A POCKET OF MODERATE INSTABILITY FROM ERN NEB AND IA SWD ACROSS MUCH
OF MO. SCATTERED THUNDERSTORMS APPEAR LIKELY TO DEVELOP ALONG THIS
CORRIDOR SATURDAY AFTERNOON WHERE FORECAST SOUNDINGS SHOW STEEP
MID-LEVEL LAPSE RATES...COLD TEMPS ALOFT AND MODERATE TO STRONG DEEP
LAYER SHEAR. THIS SHOULD BE FAVORABLE FOR SUPERCELLS AND LARGE HAIL
WITH THE GREATEST THREAT FOR LARGE HAIL EXISTING ACROSS WRN MO AND
POSSIBLY FAR NE KS IN THE EXIT REGION OF THE MID-LEVEL JET.
DIFFLUENCE AND LIFT NEAR THIS FEATURE COULD ALSO ENHANCE THE SEVERE
THREAT WITH SEVERE STORMS PERSISTING THROUGH MUCH OF SATURDAY
EVENING. AN ENHANCED WIND DAMAGE THREAT COULD DEVELOP IF A
LINE-SEGMENT CAN ORGANIZE ACROSS CNTRL AND ERN MO AS SUGGESTED BY
THE GFS. IN ADDITION...A FEW TORNADOES CAN NOT BE RULED OUT WITH THE
MORE DOMINANT CELLS ALONG THE INSTABILITY AXIS LATE SATURDAY
AFTERNOON INTO EARLY SATURDAY EVENING.

..BROYLES.. 04/23/2010

CLICK TO GET WUUS02 PTSDY2 PRODUCT

NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
CURRENT UTC TIME: 1734Z (1:34PM), RELOAD THIS PAGE TO UPDATE THE TIME

[Brent]

THE SETUP COULD BE FAVORABLE FOR STRONG TO VIOLENT TORNADOES AND A
LONG-TRACK TORNADO WILL BE POSSIBLE. AN OUTLOOK UPGRADE TO HIGH RISK
MAY BE NEEDED ACROSS PARTS OF THE REGION AS CONFIDENCE INCREASES
CONCERNING THE MODEL SOLUTIONS

Not surprised

[Bunkertor]

MESOSCALE DISCUSSION 0348
NWS STORM PREDICTION CENTER NORMAN OK
1143 AM CDT FRI APR 23 2010

AREAS AFFECTED...NERN CO...NRN KS...NEB

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

VALID 231643Z - 231745Z

SIGNIFICANT MID LEVEL DRYING HAS OVERSPREAD THE IMMEDIATE WARM
FRONTAL BOUNDARY ALONG THE NEB/KS BORDER. AS A RESULT...BOUNDARY
LAYER IS BEGINNING TO WARM SIGNIFICANTLY WITHIN MOIST ELY CONVERGENT
FLOW. LATEST DIAGNOSTIC DATA SUPPORTS THIS WITH SFC-3KM LAPSE RATES
NOW IN EXCESS OF 7 C/KM ACROSS PARTS OF NERN CO/WRN KS/EXTREME SWRN
NEB. VIS IMAGERY CERTAINLY REFLECTS THIS DESTABILIZATION PROCESS
WITH CU FIELD EXPANDING/DEEPENING ALONG THE NRN-ERN PERIPHERY OF SFC
CYCLONE. ALTHOUGH DRY SLOT WILL LIKELY SURGE A BIT FARTHER NORTH
INTO SCNTRL NEB...SIGNIFICANT WRAP AROUND MOISTURE WILL BE DRAWN
INTO THE STRONGLY CONVERGENT SFC LOW AND ROBUST THUNDERSTORM
DEVELOPMENT WILL LIKELY BE OBSERVED WITHIN THE NEXT FEW HOURS.
GIVEN THE SHEAR IN PLACE IT APPEARS SUPERCELLS AND TORNADOES ARE
POSSIBLE.

[CrazyC83]

:eek:

THE SETUP COULD BE FAVORABLE FOR STRONG TO VIOLENT TORNADOES AND A
LONG-TRACK TORNADO WILL BE POSSIBLE. AN OUTLOOK UPGRADE TO HIGH RISK
MAY BE NEEDED ACROSS PARTS OF THE REGION AS CONFIDENCE INCREASES
CONCERNING THE MODEL SOLUTIONS

Not surprised

I'm sure some wanted to pull the trigger right now, but you need incredible confidence to throw a 60% onto that map right now.

[srainhoutx]

:eek:

THE SETUP COULD BE FAVORABLE FOR STRONG TO VIOLENT TORNADOES AND A
LONG-TRACK TORNADO WILL BE POSSIBLE. AN OUTLOOK UPGRADE TO HIGH RISK
MAY BE NEEDED ACROSS PARTS OF THE REGION AS CONFIDENCE INCREASES
CONCERNING THE MODEL SOLUTIONS

Not surprised

I'm sure some wanted to pull the trigger right now, but you need incredible confidence to throw a 60% onto that map right now.

I suspect the SPC is 'laying some ground work' for tomorrow. They (SPC) just do not mention "an outlook upgrade to high risk" lightly.

[CrazyC83]

SEL0

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 80
NWS STORM PREDICTION CENTER NORMAN OK
1255 PM CDT FRI APR 23 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

PARTS OF CENTRAL AND EASTERN ARKANSAS
LARGE PART OF MISSISSIPPI
PARTS OF WESTERN TENNESSEE

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 1255 PM UNTIL
800 PM CDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
MILES EAST AND WEST OF A LINE FROM 40 MILES EAST SOUTHEAST OF MC
COMB MISSISSIPPI TO 30 MILES WEST NORTHWEST OF JONESBORO
ARKANSAS. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 79...

DISCUSSION...STRONG/SEVERE THUNDERSTORMS ACROSS LA/SRN AR WILL
CONTINUE E/NEWD INTO AN INCREASINGLY FAVORABLE ENVIRONMENT FOR
SUPERCELLS AND TORNADO DEVELOPMENT. AIR MASS CONTINUES TO
DESTABILIZE AS THE LOW LEVEL JET INCREASES TO 40KT ACROSS THE
WATCH. SUPERCELLS INCLUDING TORNADO'S AND LARGE HAIL WILL
MOVE/DEVELOP NEWD ACROSS THE LOWER MS VALLEY THIS AFTERNOON AND
EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 24035.


...HALES

[srainhoutx]

[thetruesms]

:eek:

THE SETUP COULD BE FAVORABLE FOR STRONG TO VIOLENT TORNADOES AND A
LONG-TRACK TORNADO WILL BE POSSIBLE. AN OUTLOOK UPGRADE TO HIGH RISK
MAY BE NEEDED ACROSS PARTS OF THE REGION AS CONFIDENCE INCREASES
CONCERNING THE MODEL SOLUTIONS

Not surprised

I'm sure some wanted to pull the trigger right now, but you need incredible confidence to throw a 60% onto that map right now.

I suspect the SPC is 'laying some ground work' for tomorrow. They (SPC) just do not mention "an outlook upgrade to high risk" lightly.

Indeed - just getting the mention that it's a possibility in an official product is a huge step

[thetruesms]

Interesting that the tornado warning fun begins in Colorado today

Not surprised though, as I thought the low center would have its own activity. It just started earlier than expected.

I guess I should rephrase - surprising that it was as far southwest as Limon I wonder if that warning will verify, since it was triggered by a public report, rather than law enforcement or a trained spotter.

[CrazyC83]

REALLY not liking the rapid clearing behind the Round 1 cells - pretty much clear over Texas and clearing so fast over Louisiana as well. Also the clearing ahead of the cells could turn those ones tornadic as well as we get later into the afternoon. Might be enough for a High Risk south of Little Rock and east of Longview, centered around Shreveport.

http://www.spc.noaa.gov/exper/mesoanaly ... ?sector=15

Looking at instability parameters, I would extend the Moderate Risk all the way to the Gulf Coast.

[thetruesms]

REALLY not liking the rapid clearing behind the Round 1 cells - pretty much clear over Texas and clearing so fast over Louisiana as well. Also the clearing ahead of the cells could turn those ones tornadic as well as we get later into the afternoon. Might be enough for a High Risk south of Little Rock and east of Longview, centered around Shreveport.

That field over East Texas between the cold front and current convection does really jump out, doesn't it?

[weunice]

REALLY not liking the rapid clearing behind the Round 1 cells - pretty much clear over Texas and clearing so fast over Louisiana as well. Also the clearing ahead of the cells could turn those ones tornadic as well as we get later into the afternoon. Might be enough for a High Risk south of Little Rock and east of Longview, centered around Shreveport.

Not liking the clearing either. I went to school up there and I have a lot of friends living in the Shreveport area. I am keeping them informed of the danger.

[thetruesms]

The directional shear really stands out when you watch a loop, too

[srainhoutx]

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 81
NWS STORM PREDICTION CENTER NORMAN OK
120 PM CDT FRI APR 23 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

A LARGE PART OF NEBRASKA

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 120 PM UNTIL 800
PM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 45 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 70 MILES WEST SOUTHWEST OF
MULLEN NEBRASKA TO 35 MILES SOUTH SOUTHEAST OF COLUMBUS NEBRASKA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU1).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 79...WW 80...

DISCUSSION...BANDS OF THUNDERSTORMS DEVELOPING ON THE NORTHEAST
QUADRANT OF THE DEEP SURFACE AND UPPER LOW OVER ERN CO. SUFFICIENT
MOISTURE AND INSTABILITY MOVING WWD TO SUPPORT LOW TOPPED
SUPERCELLS. TORNADOES WILL BE POSSIBLE WITH ANY SUPERCELL ALONG
WITH LARGE HAIL.

[CrazyC83]

If I drew up the 2000Z update now, it would be:

* Upgrade to High Risk over S AR, much of LA and E TX, roughly in a box cornered from De Queen, AR to Pine Bluff, AR to Alexandria, LA to Lufkin, TX (tornado 30H)

* Upgrade to Moderate Risk west to roughly Greenville, TX and down to east of San Antonio, TX (hail 45H, also tornado 15H east of I-45)

* Upgrade to Moderate Risk south to the I-10 corridor, roughly from Lafayette to Schulenburg (hail 45H, also tornado 15H from the Houston area eastward)

* Upgrade to Moderate Risk in the northern area from Columbus, NE to Kansas City, MO (hail 45H, also tornado 10H)

* Increase wind threat to 30 across W TN/AR/LA/MS

[CrazyC83]

ZCZC SPCPWOSPC ALL
WOUS40 KWNS 231731
ARZ000-LAZ000-MSZ000-OKZ000-TNZ000-TXZ000-240200-

PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1231 PM CDT FRI APR 23 2010

...SEVERE THUNDERSTORMS EXPECTED OVER PARTS OF THE LOWER MISSISSIPPI
RIVER VALLEY AND ARKLATEX VICINITY THIS AFTERNOON AND TONIGHT...

THE NWS STORM PREDICTION CENTER IN NORMAN OK IS FORECASTING THE
DEVELOPMENT OF A FEW STRONG TORNADOES AND LARGE HAIL OVER PARTS OF
THE LOWER MISSISSIPPI RIVER VALLEY AND ARKLATEX VICINITY THIS
AFTERNOON AND TONIGHT.

THE AREAS MOST LIKELY TO EXPERIENCE THIS ACTIVITY INCLUDE

ARKANSAS
NORTHERN LOUISIANA
NORTHERN AND WESTERN MISSISSIPPI
SOUTHEAST OKLAHOMA
WESTERN TENNESSEE
NORTHEAST TEXAS

ELSEWHERE...SURROUNDING THE MODERATE RISK AREA...SEVERE STORMS ARE
ALSO POSSIBLE ACROSS THE CENTRAL AND SOUTHERN PLAINS TO THE
MISSISSIPPI RIVER VALLEY.

AN UPPER LEVEL STORM SYSTEM WILL CONTINUE TO STRENGTHEN THIS
AFTERNOON AND TONIGHT WHILE TRANSITIONING FROM THE SOUTHERN ROCKIES
TO THE SOUTHERN PLAINS THROUGH EARLY SATURDAY. A COLD FRONT WILL
SPREAD EASTWARD ACROSS THE MISSOURI RIVER VALLEY...EASTERN
OKLAHOMA...AND PORTIONS OF EAST-CENTRAL TEXAS THROUGH TONIGHT.

AHEAD OF THE COLD FRONT...A WARM...INCREASINGLY MOIST...AND UNSTABLE
AIR MASS WILL DEVELOP NORTHWARD ACROSS THE SOUTH CENTRAL STATES
TODAY. STRONG TO SEVERE THUNDERSTORMS WILL CONTINUE TO INCREASE AND
SPREAD EAST-NORTHEASTWARD ACROSS THE MISSISSIPPI RIVER VALLEY THIS
AFTERNOON AND EVENING. ATMOSPHERIC CONDITIONS WILL SUPPORT A RISK OF
SEVERE THUNDERSTORMS CAPABLE OF TORNADOES...A FEW OF WHICH MAY BE
STRONG.

LATER TONIGHT...A SECONDARY ROUND OF SEVERE THUNDERSTORMS WILL
LIKELY DEVELOP THIS EVENING AND ESPECIALLY OVERNIGHT ACROSS
NORTHEAST AND CENTRAL TEXAS...AS WELL AS SOUTHEAST OKLAHOMA. AS
THESE STORMS RACE EAST-NORTHEASTWARD LATE TONIGHT AND EARLY
SATURDAY...LARGE HAIL...DAMAGING WINDS...AND A FEW TORNADOES WILL
ALL BE POSSIBLE.

ON SATURDAY...A SIGNIFICANT AND POTENTIALLY EXTENSIVE SEVERE WEATHER
RISK...INCLUDING THE POSSIBILITY OF AN OUTBREAK WITH STRONG
TORNADOES...IS EXPECTED ACROSS THE LOWER MISSISSIPPI RIVER
VALLEY...TENNESSEE VALLEY...AND CENTRAL GULF COAST STATES.


..GUYER.. 04/23/2010

$$