Severe weather 4/25-4/27

[JFord]

In this case I suspect night time was the main reason. The storms really tailed off at 10pm last night. Baton Rouge had some high wind. The next two days have the potential to be historic in the south.

It as if it happens every time though. Since I have lived in Ruston (2003) severe storms are never as severe as they are predicted, again I am thankful.

[weunice]

It is just good fortune. There were towns in Kansas that avoided significant tornadoes for decades to the point that the locals somehow thought their towns were protected only after all those years to have the town significantly impacted by a major tornado. No forest, dip, river, hill, city skyline or mountain is going to stop a significant tornado in a good environment. The Salt Lake tornado crossed the continental divide and if that wasn't a deterrent not much in north Louisiana is either. Fact is the Shreveport area has been impacted by multiple F4's and NE LA has seen an F5. I am not saying that means Ruston will be one day. It may never happen in our lifetimes. Then again, it could happen today.

All we know is that conditions are favorable. Hopefully something will upset the setup and today will be a big bust.

[CaseyDawg]

http://arkansasmatters.com/fulltext/?nxd_id=416547

I live about a mile on the other side of the watertower.

[Champ967]

Busts are possible of course

OR ?????

[Allgood]

Dr. Forbes on Weather channel just upgraded his "Tor-Con" value for N. Louisiana to an 8 and a 9 for NE TX and S. Ark. 8 meaning an 80% (9-90%) chance of a tornado within 50 miles of the designated area. Given N. La had a 5 last night and the squall line parted as soon as it hit the TX/LA border, I think you can travel to Arkansas for a good lightning show. But if you live in, or have relatives in southern Arkansas, you may want to make some phone calls.

[weunice]

SPC is likely to expand the high risk area into the Memphis and surrounding areas.



MESOSCALE DISCUSSION 0585 NWS STORM PREDICTION CENTER NORMAN OK 1051 AM CDT TUE APR 26 2011 AREAS AFFECTED...FAR EASTERN AR/SOUTHWEST TN/NORTHERN MS CONCERNING...OUTLOOK UPGRADE VALID 261551Z - 261645Z THE EXISTING CATEGORICAL HIGH RISK WILL LIKELY BE EXPANDED NORTHEASTWARD IN THE FORTHCOMING 1630Z DAY 1 OUTLOOK TO INCLUDE REMAINING PORTIONS OF EASTERN AR...WHILE ADDING PARTS OF SOUTHWEST TN/NORTHWEST MS INTO A HIGH RISK. FOR ADDITIONAL METEOROLOGICAL DISCUSSION...SEE THE FORTHCOMING DAY 1 OUTLOOK THAT WILL BE ISSUED BY AROUND 1630Z. ..GUYER.. 04/26/2011

[Allgood]

If you like it a little more cut and dry and can pick through confusing graphics, this is an "experimental" web video briefing from a meteorologist from the Storm Prediction Center this morning.

[splicer]

I've heard it described as the Monroe Hole (have at it Champ). Because of the valley starting about at the parish line, storms split and go around Monroe, and re-form on the other side.

[weunice]

I don't buy the hole and mostly because I have read one too many stories of towns having been hammered after decades of nothing. For local reference ...

There was an F3 in Ouachita Parish 02/01/1968
There was an F4 in Ouachita Parish 04/01/1983
There have also been more than the occasional F2 in Ouachita (4 since 1950) and Lincoln (8 since 1950) parishes.
The lone Louisiana F5 was 02/21/1971 and it went through Madison and East Carroll before moving into Mississippi.

Not exactly common but not unheard of. There has not been a violent tornado (EF-4+) in south Louisiana that was not part of a landfalling hurricane since 1950 which is the time frame you will find for most searchable records. It makes me feel safe at times to review that fact. Then again, I know a little more about the history of storms around here than the average Joe. In 1908 one of the deadliest tornadoes in American history trekked through Amite LA and nearly completely destroyed Purvis MS. It was believed to have been an F4.

[Dr Twister]

I don't buy the hole and mostly because I have read one too many stories of towns having been hammered after decades of nothing. For local reference ...

There was an F3 in Ouachita Parish 02/01/1968
There was an F4 in Ouachita Parish 04/01/1983
There have also been more than the occasional F2 in Ouachita (4 since 1950) and Lincoln (8 since 1950) parishes.
The lone Louisiana F5 was 02/21/1971 and it went through Madison and East Carroll before moving into Mississippi.

Not exactly common but not unheard of. There has not been a violent tornado (EF-4+) in south Louisiana that was not part of a landfalling hurricane since 1950 which is the time frame you will find for most searchable records. It makes me feel safe at times to review that fact. Then again, I know a little more about the history of storms around here than the average Joe. In 1908 one of the deadliest tornadoes in American history trekked through Amite LA and nearly completely destroyed Purvis MS. It was believed to have been an F4.

And I thought I was suppose to be the tornado fanatic on this board. Should have hired weunice to work on one of my field teams for Vortex2..he's more energetic than some of the crew I have now.

[ITdrummer]

My mom is an Asst. Principal at a Bossier Parrish high school and received this in an email:

Subject: Severe Weather Event Potential Tuesday/Overnight

Subject: NWS Webinar Notes

• Upgraded to High Risk along I-30 corridor and North of I-20 which includes the northern part of Caddo and Bossier Parishes
• Moderate Risk along I-20 corridor and southern part of Caddo and Bossier Parishes
• Significant damaging wind threat (90+ mph possible), strong to violent tornados possible and large hail possible
• High risk for strong tornados (EF2 or higher)
o 30% chance (this means there is a 30% chance of tornados occurring within 25 miles of a point)
• Hail threat of greater than 2” hail North of I-20
• Very high risk Bow Echoes North of I-20
o Wind threat will evolve/increase with time…become later in evening/overnight
o Falling trees will be significant risk during overnight hours
o Widespread power outages possible
• Caddo-Bossier can expect 1-2” of rainfall Tuesday-Wednesday
• Timeline for Caddo-Bossier could start as early as 6:00 PM but more likely into overnight hours, especially damaging wind threat. Hard to predict exact timeline because there is potential for several waves of this system.

Just passing it along.

[splicer]

I don't buy the hole and mostly because I have read one too many stories of towns having been hammered after decades of nothing. For local reference ...

There was an F3 in Ouachita Parish 02/01/1968
There was an F4 in Ouachita Parish 04/01/1983
There have also been more than the occasional F2 in Ouachita (4 since 1950) and Lincoln (8 since 1950) parishes.
The lone Louisiana F5 was 02/21/1971 and it went through Madison and East Carroll before moving into Mississippi.

Not exactly common but not unheard of. There has not been a violent tornado (EF-4+) in south Louisiana that was not part of a landfalling hurricane since 1950 which is the time frame you will find for most searchable records. It makes me feel safe at times to review that fact. Then again, I know a little more about the history of storms around here than the average Joe. In 1908 one of the deadliest tornadoes in American history trekked through Amite LA and nearly completely destroyed Purvis MS. It was believed to have been an F4.

I don't think anyone said that bad weather doesn't happen here, but that it has a tendency to split up here. I wedged my truck inside the garage last night in case a hail storm came, and have a couple of other nights this year. I still take precautions, but it's an interesting observation from others that they see the same weather patterns that I have, and have heard of in the past. There must be something to explain the breakup along the parish line.

Even in your data, there were twice the number of tornadoes in Lincoln Parish than there were in Ouachita Parish in the last 60+ years.

[weunice]

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 215
NWS STORM PREDICTION CENTER NORMAN OK
145 PM CDT TUE APR 26 2011

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

SOUTHERN AND CENTRAL ARKANSAS
NORTHERN LOUISIANA
EXTREME SOUTHEAST OKLAHOMA
NORTHEAST AND NORTH CENTRAL TEXAS

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 145 PM UNTIL
1000 PM CDT.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

DESTRUCTIVE TORNADOES...LARGE HAIL TO 4 INCHES IN DIAMETER...
THUNDERSTORM WIND GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE
POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTHWEST OF WACO
TEXAS TO 60 MILES NORTHEAST OF EL DORADO ARKANSAS. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU5).

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 213...WW 214...

DISCUSSION...SEVERE THUNDERSTORMS ARE EXPECTED TO RAPIDLY DEVELOP
THIS AFTERNOON OVER NORTHEAST TX...SPREADING ACROSS THE WATCH AREA
THROUGH EARLY EVENING. OTHER INTENSE STORMS WILL DEVELOP BY EARLY
EVENING OVER NORTHEAST TX AND ALSO SPREAD EASTWARD. BOTH AREAS OF
SEVERE STORMS WILL LIKELY INCLUDE DISCRETE SUPERCELLS CAPABLE OF
VERY LARGE HAIL...DAMAGING WINDS...AND TORNADOES. WIND FIELDS WILL
BE STRENGTHENING THROUGH THE EVENING...AND STORMS TRACKING NEAR THE
EXISTING BOUNDARY FROM TX INTO AR WILL HAVE ENHANCED SHEAR AND THE
RISK OF STRONG/LONG-LIVED TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
600. MEAN STORM MOTION VECTOR 25035.

[weunice]

I don't think anyone said that bad weather doesn't happen here, but that it has a tendency to split up here. I wedged my truck inside the garage last night in case a hail storm came, and have a couple of other nights this year. I still take precautions, but it's an interesting observation from others that they see the same weather patterns that I have, and have heard of in the past. There must be something to explain the breakup along the parish line.

Even in your data, there were twice the number of tornadoes in Lincoln Parish than there were in Ouachita Parish in the last 60+ years.

All I'll say is that past performance is not an indication of future returns You can have an area go 100 years with nothing and then 5 straight with unreal numbers of incidents. Such is the nature of unusual things.

Dr. Twister I would have LOVED to have been on that team My wife on the other hand ....

[weunice]

Note: The parallelogram is only an approximation to the watch, the actual watch is defined by the outlines of the counties contained in it.

Tornadoes
Probability of 2 or more tornadoes

High (>95%)

Probability of 1 or more strong (F2-F5) tornadoes

High (90%)

Wind
Probability of 10 or more severe wind events

High (90%)

Probability of 1 or more wind events > 65 knots

High (80%)

Hail
Probability of 10 or more severe hail events

High (>95%)

Probability of 1 or more hailstones > 2 inches

High (>95%)

[COLOR=rgb(153, 51 255)]Combined Severe Hail/Wind[/COLOR]
Probability of 6 or more combined severe hail/wind events

High (>95%)

For each watch, probabilities for particular events inside the watch (listed above in each table) are determined by the issuing forecaster. The "Low" category contains probability values ranging from less than 2% to 20% (F2-F5 tornadoes), less than 5% to 20% (all other probabilities), "Moderate" from 30% to 60%, and "High" from 70% to greater than 95%. High values are bolded and lighter in color to provide awareness of an increased threat for a particular event.