Pushing The Envelope
I'm at a Severe Storms & Doppler Conference in Des Moines, focused on best practices for tornado prediction. We've made progress: advanced lead-time for tornadoes has gone from 6 minutes in the 70s to 13 minutes today. Predicting polygon tracks means fewer people have to be warned, cutting down on confusion. But the false alarm rate is still 75 percent. In other words, 3 out of 4 warnings don't produce an actual tornado.
NOAA will use more emphatic wording in 2013, especially when there is confirmation of a tornado on the ground. Expect to hear words like "catastrophic", even "you could be killed if you aren't in a basement or underground shelter" if there is a large, violent tornado on the ground, moving into a populated area. New, high-res models, capable of a 40-60 minute tornado probability, are probably 4-8 years away. Hospitals and businesses may get advance notice of a high probability of tornadoes before general consumers, giving them more time to prepare, move patients and employees, etc. The WSR-88D "NEXRAD" Doppler radars are almost 25 years old, and at some point they will be replaced, possibly with "phased-array radars" that can take a 3-D snapshot of the atmosphere within seconds vs. minutes, speeding up the tracking and warning process.
One problem: many people still wait to get confirmation from multiple sources (TV, radio, apps, a phone call) before they do the right thing and head for shelter. Waiting for confirmation can cost you your life; apathy and delay (along with a lack of basements) resulted in 161 deaths from Joplin's EF5 tornado on May 22, 2011.
A major severe outbreak is shaping up for the Southern Plains early next week. Closer to home the risk of Red River flooding will rise in coming weeks.
Rain is likely today, but a major southern storm may drop over 1" rain Monday & Tuesday; possibly ending as midweek slush.
Something to look forward to.
Major Severe Storm Outbreak Next Week? All the dynamics are coming together for a potentially significant outbreak of severe storms and tornadoes the first half of next week. D4 refers to Monday, D5 is Tuesday, the green area shaded D6 spills into Wednesday of next week. Low-level moisture, severe instability and a strong jet streak rotating around a deep trough of low pressure could set the stage for a series of large, violent, long-track tornadoes. Map above: SPC.
NOAA Needs Your Help. The local Twin Cities National Weather Service is interested in knowing whether the ground is still frozen in your neighborhood. Why does this matter? The extent and depth of lingering frost in the ground will help to determine rainfall run-off rates next week, when we may see a significant storm. This will impact not only the potential for minor flash flooding in the Twin Cities, but more significant river flooding, especially on the Red River in the weeks to come. Details: "As we head in to Spring, potential flooding is a primary concern across Minnesota and Wisconsin. We could use your help in determining if the ground is still frozen, or if there has been some partial thaw of the ground. As you can see on the map below, we have quite a large area with no data across southern MN and western WI. Visit our Facebook Page or send us a message via Twitter @NWSTwinCities and let us know what the ground condition is like at your location."
- Snow depths range from zero in the
southern one-third of Minnesota to over 20 inches west central
Minnesota, north central Minnesota, and in the Lake Superior highlands.
[see: NWS Snow Depth Estimation Map | Snow Depth Maps]
- The amount of water content in the snow pack
is estimated to be in excess of five inches in some west central and
north central Minnesota counties. The large amount of water on the
landscape, lying upon an impervious frozen surface, has led to a high risk for major flooding in the Red River basin.
[see: NWS Snow Water Equivalent Estimation Map]
- The U.S. Geological Survey and Minnesota DNR report that stream discharge values
vary widely across the state. After the initial flush of snow melt
runoff recedes, stream discharge values will quickly fall below
historical medians unless there is a very wet spring.
[see: USGS Stream Flow Conditions | MNDNR Weekly Stream Flow Maps and Tables]
- Water levels on most Minnesota lakes are low due to the dry summer and autumn of 2012. Lake Superior's water level is approximately one foot lower than its historical average for this time of year.
Photo credit above: "The flooded Red River surrounds houses near Fargo, N.D., in 2010. Scientists say climate change will produce more intense storms, increasing the risk of damaging floods." (M. Spencer Green / Assoicated Press / March 21, 2010)
* The Los Angeles Times has another perspective on the potential for more extreme rains here.