Tuesday, April 6, 2010

A perpetual state of spring fever

Monster-Spark. The most dangerous part of a thunderstorm is at the very beginning and the end. Just because it's not raining doesn't mean there isn't a significant risk of being struck by cloud to ground lightning. You're heard the expression "bolt from the blue", or "out of the blue"? every year a handful of Americans are struck and killed by lightning, blue sky overhead, a thunderstorm 5-10 miles away on the horizon. Lightning has been known to travel up to 10 miles (horizontally) on rare occasions. The good news: if you do the right thing, if you're in a building (or vehicle) you're relatively safe. And an estimated 8 out of 10 people struck by lightning (who's heart appears to have stopped, not breathing) can be successfully resuscitated by prompt CPR. Last year 39 Americans were killed by lightning, hundreds of others were permanently injured. Click here to see a great explainer about lightning safety from NOAA - now would be a good time to review lightning (and tornado) safety tips with your family.
Enlighten Me. Data is delayed by 30 minutes - it's NOT real-time. But here is a FREE web site that allows you to track lightning across the USA. The more recent lightning strikes show up as white, the older strikes are yellow - so you can infer the motion of the storms. Again, a good tool, but don't rely on this for anything close to real-time strikes. Note a few isolated strikes near Winona and Lake City late Tuesday - that was pretty much the northern extent of the T-storm outbreak.

A shocking development: it actually rained Tuesday. That odd, liquid substance falling from the heavens was a sight for sore (dry) eyes, not the soaking we needed, but a big, sloppy step in the right direction. Officially a whopping .04" of rain fell at MSP, enough to settle the dust, but a rounding error when it comes to replenishing soil moisture and giving fields, lawns, shrubs, trees and gardens the long, cool swig of water they need at this point in the season. True, another potential storm is shaping up for early next week (even an outside chance of the first widespread severe storm outbreak by next Tuesday) but I don't see the soaking, drenching rain event we really need to catch up for a dry March (rainfall a third of what it should have been).

Tuesday Rainfall. Doppler radar estimates range from .05" to .25" for far southern Minnesota, but some 1"+ amounts were reported near the Wisconsin Dells, closer to a warm frontal boundary that acted as a magnet for thunderstorms, some severe. See rainfall for the last 24 hours for the USA (you can zoom into Minnesota or any other location) by clicking here.

Close Call. A severe thunderstorm watch was issued late Tuesday for the southern third of Wisconsin - a few thunderstorm cells near Des Moines were "tornadic", rotating rapidly, symptoms of a "supercell" storm capable of large hail or tornadoes.

Skies begin to clear today - you'll need a jacket this morning, but under a partly cloudy sky it should feel pretty good out there later today, highs reaching the mid 50s. As winds turn around to the southwest tomorrow temperatures will moderate - highs reach into the 60s, 70 not absolutely out of the question late Friday and again Saturday. A dying cool front will limp across the state late Saturday, sparking a few widely scattered late PM showers (mainly central counties). That front will do a U-Turn and return north again Sunday, sparking another shower/thunder risk, especially late afternoon and evening - the metro area stands a better chance of an hour or two of rain late Sunday afternoon/evening. Most of the weekend will be dry, Saturday still appears to be the nicer, milder day - temperatures cooling off a few degrees Sunday (but still 10-15 degrees above average!)

Severe Outbreak? It's way too early to try and get specific about timing or severity, but some of the ingredients seem to be converging for a possible severe thunderstorm outbreak next Monday - Wednesday of next week, as Minnesota breaks out into the "warm sector" of an approaching storm. There may be sufficient wind shear (changing wind direction/speed rising up through the atmosphere), low-level moisture (dew point temperatures in the 50s, even low 60s) and instability (temperatures cooling faster with altitude than usual) to spark a few isolated severe storms nearby - best chance probably Tuesday. We'll keep fine-tuning that risk.

Gentle Reminder: it is still April out there. Sorry - forgot to include this on April 1. Running around the office like a crazy-man, but here are the April averages and records for each day.

Snow? Don't see it. Cold fronts? Nope. Expect highs mostly in the 50s, 60s, even a few low 70s (southern MN) looking out the next 15 days, through April 20, give or take. I keep waiting for the other shoe to drop (I've been waiting since mid February!) We're in a rut, big storms rumbling across the Pacific Northwest, regrouping over the Deep South, then roaring up the east coast. Meanwhile Minnesotans have been reduced to the role of bewildered observers, watching the parade of storms to our south, sitting up here, smiles of contentment, watching an ongoing spell of May-like conditions in early April. It IS still early April, right? Some days I have to stop, think, and consult my calendar to be sure.

What a spring....a REAL spring!

Tracking Extremes. Check out coolwx.com for some fascinating maps, graphs and statistics. For example, did you know that the warmest temperature in the last 24 hours was 109.4 in Garoua, Cameroon? The coldest reading, at a regular-reporting weather station? -70.6 F at the Amundsen-Scott research station in Antarctica? Or the last reported funnel cloud (near a weather station) was spotted at Broomfield, Colorado? If you want to guarantee that people will migrate away from you at the next party, dig in - time to share!

A World of Extremes. Sample pages from coolwx.com. Click the box at the center of the home page - pretty cool.

Brazil Flooding. Rio de Janiero hasn't seen rains like this in decades, some 10-20" rainfall amounts have triggered widespread flooding, mudslides - much of the country has been paralyzed by massive rivers of mud and muck. The death toll is already up to 98, and sadly, rising as fast as the flood waters. Thunderstorms have been persistent, reforming over the same regions, pouring out several month's worth of rain in the span of a few days. Last weekend Peru was hit by landslides that left at least 28 people dead - now that same zone of troubled, slow-moving weather has set up over Brazil. The story is here.

Paul's Conservation MN Outlook for the Twin Cities and all of Minnesota

Today: Damp, cool start. Getting sunnier as the day goes on - stiff wind. Winds: N 10-20. High: 55

Tonight: Clearing and chilly, frost possible far outlying suburbs. Low: 37

Thursday: Plenty of sun, milder (less wind). High: 61

Friday: Lot's of sun, nice way to end the work-week. High: 68

Saturday: Probably the nicer day. Partly cloudy, mild - late PM shower up north? High: 67

Sunday: Mix of clouds and sunshine, slight shower/thunder risk late. High: 62

Monday: Unsettled, more numerous showers, possible T-storms. high: 66

Tuesday: Humid, scattered showers/storms, some strong to severe? High: 64

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