Alex Lamers
EF4
ENSO ANALOGS
One of my favorite techniques to use, and one that has been successful over the past several years, is to do comparative ENSO analogs and then compile active areas to predict "active" and "dormant" areas of the country as far as severe weather goes. In 2005 we came out of a weak El Nino and went into fluctuating neutral conditions. Neutral to weak La Nina conditions are projected for most of 2006 and this was taken into account. The matching analogs are: 1953, 1959, 1967, 1979, 1984.
What was found was a consistent belt of very active weather across the Central United States, stretching from Minnesota and Wisconsin southwest into tornado alley and eventually bending back around to the Arklatex. The Central/Eastern Great Lakes were generally quiet despite a few concentrations of more active weather in Indiana and Michigan. The Southeast was pretty average as was the Central Atlantic Coast. The Northeast was rather quiet as well with no major events. The west was generally average (sporadic severe as per usual) except for a bit of a void across the Four Corners region and a concentration of active weather on the Frontrange east of Denver.
The two major corridors in the larger active weather zone extended from C/E Nebraska and N Kansas east-northeast into N Missouri, Iowa, and S Minnesota as well as from N Texas and Oklahoma east-southeast into Arkansas and N/C Louisiana and W Mississippi. These included some larger outbreaks of tornadic activity and even long-track and violent tornadoes. One can't forget the deadly one-two punch of the Barneveld F5 tornado and the Wales F4 tornado in Wisconsin in 1984.
CLIMATE OUTLOOKS
The CPC outlooks lend for a general trend of above-average temperatures likely near the Gulf Coast and the Western US, with above-average precipitation over the Upper Mississippi River Valley during the summer months. The spring and fall months are pretty much equal chances in most major concern areas. Not much to be gleaned from this although drier conditions across the south for the next three months and building temperatures could lead the drought to persist across the Southern Plains which could negatively impact the primary convective season down there.
DROUGHT OUTLOOKS
Speaking of droughts, we look at the CPC drought outlook which forecasts Oklahoma, Texas and Western Arkansas to remain firmly in the grasp of a nasty drought through March which could impact available moisture during early season systems and perhaps even transpirational effects later in the season. There is forecast to be some improvement in the drought over the upper reaches of the Mississippi Valley, but the drought conditions should generally persist over S/C Iowa and N/W Illinois.
LA NINA?
If we do in fact enter a weak La Nina pattern, what does this typically signal in terms of overall flow pattern adjustments? SST anomaly depth loops show an expanding pool of anomalously cool water in the equatorial Pacific not only horizontally but in depth through about 200 meters. La Nina would tend to adjust to more of a mean southwest flow over the US with abnormally wet conditions over the Central US and Ohio/Tennessee Valleys...and hot/dry weather over the Southern states. A lot of major outbreaks have taken place during negative Oceanic Nino Index periods including: Superoutbreak of 1974, Palm Sunday Outbreak of 1965, May 3rd outbreak of 1999, 1996's active season including F5 Oakfield, WI tornado, The May 1988 Mother's Day Outbreak and many more. Extended forecast graphics for the summer months show a flow pattern similar to La Nina periods and thus we could potentially see a weak La Nina or small negative ONI period begin.
IN SUMMARY
All of the factors considered some general conclusions can be drawn. We should operate under the assumption that general La Nina flow patterns will become more common over the severe weather season which means potentially active weather over Tornado Alley and the Mississippi and Ohio River Valleys. With a persistent drought and generally unfavorable conditions under negative ONI or weak La Nina periods, the Gulf Coast could be rather dormant severe-weather wise. The Northeast should be cool and wet, but not necessarily active or dormant severe-weather wise. We could see abnormally dry conditions take hold in the west again as well.
Nevermind the image didn't work. LOL Red-shaded active area was pretty much tornado alley north of Central Oklahoma and also extending into AR/LA and WI/IL/IN/MI. Inactive was the far S Plains and the Southeast and the Mid Atlantic.
In addition, based on the long history of intense tornado outbreaks and long-tracked violent tornadoes both in the analog years and in La Nina or slightly below neutral years, it would not be surprising if a couple notable outbreaks occurred in 2006, particularly in April-June and particularly across the red shaded area on the above map. It also would not be surprising to see a couple long-tracked tornadoes over 50 NM in track length and of F3-F5 intensity.
...Alex Lamers...
**posted earlier in January for my personal use**
One of my favorite techniques to use, and one that has been successful over the past several years, is to do comparative ENSO analogs and then compile active areas to predict "active" and "dormant" areas of the country as far as severe weather goes. In 2005 we came out of a weak El Nino and went into fluctuating neutral conditions. Neutral to weak La Nina conditions are projected for most of 2006 and this was taken into account. The matching analogs are: 1953, 1959, 1967, 1979, 1984.
What was found was a consistent belt of very active weather across the Central United States, stretching from Minnesota and Wisconsin southwest into tornado alley and eventually bending back around to the Arklatex. The Central/Eastern Great Lakes were generally quiet despite a few concentrations of more active weather in Indiana and Michigan. The Southeast was pretty average as was the Central Atlantic Coast. The Northeast was rather quiet as well with no major events. The west was generally average (sporadic severe as per usual) except for a bit of a void across the Four Corners region and a concentration of active weather on the Frontrange east of Denver.
The two major corridors in the larger active weather zone extended from C/E Nebraska and N Kansas east-northeast into N Missouri, Iowa, and S Minnesota as well as from N Texas and Oklahoma east-southeast into Arkansas and N/C Louisiana and W Mississippi. These included some larger outbreaks of tornadic activity and even long-track and violent tornadoes. One can't forget the deadly one-two punch of the Barneveld F5 tornado and the Wales F4 tornado in Wisconsin in 1984.
CLIMATE OUTLOOKS
The CPC outlooks lend for a general trend of above-average temperatures likely near the Gulf Coast and the Western US, with above-average precipitation over the Upper Mississippi River Valley during the summer months. The spring and fall months are pretty much equal chances in most major concern areas. Not much to be gleaned from this although drier conditions across the south for the next three months and building temperatures could lead the drought to persist across the Southern Plains which could negatively impact the primary convective season down there.
DROUGHT OUTLOOKS
Speaking of droughts, we look at the CPC drought outlook which forecasts Oklahoma, Texas and Western Arkansas to remain firmly in the grasp of a nasty drought through March which could impact available moisture during early season systems and perhaps even transpirational effects later in the season. There is forecast to be some improvement in the drought over the upper reaches of the Mississippi Valley, but the drought conditions should generally persist over S/C Iowa and N/W Illinois.
LA NINA?
If we do in fact enter a weak La Nina pattern, what does this typically signal in terms of overall flow pattern adjustments? SST anomaly depth loops show an expanding pool of anomalously cool water in the equatorial Pacific not only horizontally but in depth through about 200 meters. La Nina would tend to adjust to more of a mean southwest flow over the US with abnormally wet conditions over the Central US and Ohio/Tennessee Valleys...and hot/dry weather over the Southern states. A lot of major outbreaks have taken place during negative Oceanic Nino Index periods including: Superoutbreak of 1974, Palm Sunday Outbreak of 1965, May 3rd outbreak of 1999, 1996's active season including F5 Oakfield, WI tornado, The May 1988 Mother's Day Outbreak and many more. Extended forecast graphics for the summer months show a flow pattern similar to La Nina periods and thus we could potentially see a weak La Nina or small negative ONI period begin.
IN SUMMARY
All of the factors considered some general conclusions can be drawn. We should operate under the assumption that general La Nina flow patterns will become more common over the severe weather season which means potentially active weather over Tornado Alley and the Mississippi and Ohio River Valleys. With a persistent drought and generally unfavorable conditions under negative ONI or weak La Nina periods, the Gulf Coast could be rather dormant severe-weather wise. The Northeast should be cool and wet, but not necessarily active or dormant severe-weather wise. We could see abnormally dry conditions take hold in the west again as well.
Nevermind the image didn't work. LOL Red-shaded active area was pretty much tornado alley north of Central Oklahoma and also extending into AR/LA and WI/IL/IN/MI. Inactive was the far S Plains and the Southeast and the Mid Atlantic.
In addition, based on the long history of intense tornado outbreaks and long-tracked violent tornadoes both in the analog years and in La Nina or slightly below neutral years, it would not be surprising if a couple notable outbreaks occurred in 2006, particularly in April-June and particularly across the red shaded area on the above map. It also would not be surprising to see a couple long-tracked tornadoes over 50 NM in track length and of F3-F5 intensity.
...Alex Lamers...
**posted earlier in January for my personal use**
