Thursday, March 18, 2010

Jacket Weather Returns

* As of Thursday, Twin Cities temperatures were running 9.4 degree F warmer than average.

* March snowfall so far: zero. Normal March snow as of March 19: 7.4"

Man, are we ever getting spoiled. 64 on Thursday, 23 degrees above average for this date, weather more typical of early May. It doesn't take a rocket scientist to deduce that all this unusual warmth is accelerating snow melt (and ice melt - stay off area lakes!) but there is one saving grace: we haven't seen heavy precipitation for about a week. Falling rain would (greatly) accelerate the melting of snow lingering over far southern and western Minnesota, so we've been lucky that a bad flood situation hasn't been made even worse by additional rain or snow.

Tell-Tale Signs of an Ice Jam. Check out the actual river levels on the Mississippi River at St. Cloud. The spikes in water levels MAY be the result of ice jams forming (and breaking) upstream, especially on the Sauk River. The good news: the level of the river at St. Cloud is forecast to steadily drop now through next week. The latest forecast for St. Cloud is here.

Nervous River Forecasters. Every new computer run seems to be pushing the expected crest of the Mississippi River in St. Paul by a few inches. The new forecast crest is close to 20' by next Tuesday/Wednesday, still over 6 feet lower than the historical crest in St. Paul. But at these "major" flood stages there would be lowland flooding and significant road closures, inundation of farm land, etc. The latest forecast is here.

More like mid April. In just the last week we've seen 3 days of 60+ F. weather. Keep in mind the average high now is 41 F. What the heck has happened to average? Check out the climate information from the NWS and the MN State Climatology Office here.

Lingering El Nino Signals
. With the atmosphere it's virtually impossible to predict cause and effect, but what we're seeing is consistent with a slowly weakening El Nino phenomenon in the Pacific: stormy across the south and east, unusually warm (and relatively dry) over the northern tier states. Click here to go to Ham Weather (a division of WeatherNation) to interactively explore the details of all these records. BTW, the red dots represent cities experiencing record highs since Wednesday.

What March? Another near-miss. Check out expected snowfall over the next 84 hours, a cool 5-10" possible in Denver Friday (expect massive delays at some cancellations at Denver area airports). Des Moines, Iowa may pick up 2-4" of slush, with some 6-10" amounts forecast for parts of Missouri. The locals are going to be VERY unhappy.

Denver is a wonderful city - great climate, plenty for outdoor lovers to do. For the next couple of days don't let anyone living in the Mile High City give you a hard time about hanging out in Denver. On Thursday the mercury soared into the mid 60s in Denver - tomorrow it will snow, possibly 5-10". True, most of it will be gone by next Monday, but still. Following the trend of recent weeks this next storm will track off well south of Minnesota, brushing Iowa with a couple inches of slush. Across parts of Missouri it may be more than a "brushing", as much as 4-8"+ snow may fall!

Today's cool front (I hesitate to call 40s a "cold front", not after what we've been through) should come through dry, nothing more than a few sprinkles, may be a stray flurry up north. Grab a hefty jacket, you'll need it through the day on Saturday as temperatures return to within a few degrees of "average" for mid March. Expect more sun and less wind on Sunday, temperatures mellowing to near 50 again. Now that the snow is mostly-gone, the sun's ample energy (as high in the sky as it was in late September now!) can go into heating up the air, not melting snow. Next week appears more "active", a growing chance of a rain-snow mix next Tuesday/Wednesday, although right now I don't think anything will stick, temperatures at the surface too warm for any slushy, slippery headaches. In fact the very latest GFS computer run pretty much kills off next week's "storm", keeping precipitation to our south. Where have we heard that before? It's getting to be a habit - hopefully one that won't linger into spring planting season, when farmer and gardeners hope for some well-timed rain events.

Expect 40s, even a few low 50s next week (although that's probably it for the 60s until the first few days of April). No Denver-esque snow storms, no heavy rain to exacerbate the flood threat. In spite of today's cool down temperatures looking out the next 15 days or so should average 3-8 degrees above normal through the period. Will we get accumulating snow in March? Could we actually see even less than the paltry, puny 1.5" that fell during March of 2009? At the rate we're going, the answer is a qualified yes. Don't bet the farm on that one....

Flooding from the Air. Flying back to MSP yesterday the Delta 757 passed directly over the Mayer area, just south/west of the metro area, the South Fork of the Crow River was clearly visible; well out of its banks, forecast to crest just above 16 feet Friday. For perspective the record crest in Mayer in 19 feet, 2". The latest forecast for Mayer is here.

Rapid Ice Out? Lake Minnetonka from an altitude of 8,000 feet on Thursday. The darker the ice, the thinner and more unstable it is. A word to the wise: stay off the ice!

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

Today: More clouds than sun, windy and cooler. Winds: NW 15-25. High: 40

Tonight: Partly cloudy and brisk - jacket weather. High: 28

Saturday: Partly sunny and seasonably cool. High: 38

Sunday: Bright sun, less wind. High: 51

Monday: Sun giving way to increasing clouds. High: 49

Tuesday: Mostly cloudy, a few light showers of rain (or snow) possible. High: 48

Wednesday: Sprinkles/flurries end - gradual clearing. High: 47

Thursday: Mostly cloudy - unsettled. High: 49

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