Tuesday, May 18, 2010
80 by the weekend (with a growing thunder risk)
Growing Drought. According to the U.S. Drought Monitor 14% of the Upper Midwest is experiencing moderate drought, as of May 11, in spite of the rain that fell during the first week of May. I'm still concerned about the potential for widespread drought spreading across much of Minnesota this summer. The trend has been for wet, sloppy storms to pass south of MN, that has translated into a dry trend for us, but the silver lining: severe storms have also passed off well south of town. Too early to be overly concerned - but it bears watching.
Minnesota Drought. Just over 30% of MN is still experiencing moderate drought, little change from the beginning of the month. 5% of the state (along the North Shore) is in a severe drought, up from 0% on May 4. A stubborn bubble of high pressure over the Great Lakes for much of March, April and May has meant unusually sunny, dry weather from the North Shore to the U.P. of Michigan. Click here for more details from NOAA's Drought Monitor.
Tuesday Almanac. What a day, worth one more look. Highs were pretty uniform statewide, as warm as 78 at St. Cloud, 80 at Redwood Falls, more like late May. As good as it ever gets, in mid May, at this latitude.
Another day in Paradise. Tuesday was remarkable (nice to have the sunshine without the eye-watering, hair-curling winds whipping up from the south). It was as close to perfect as you'll ever see in May, and it looks like the Weather Honeymoon will hang on a few more days as high pressure camps out over the Great Lakes. Blue sky, a light breeze (blowing from the southeast), low humidity - the bugs have yet to discover how amazing the weather is in Minnesota - you will be daydreaming by 10 am, by noon you'll be itching for an outdoor lunch. Make up excuses, offer to run errands for your boss, ANYTHING to get your butt out the door, basking under a mid-May sun.
Precipitation Trend. Dry weather prevails through Thursday, but all the weather models are printing out a little rain Friday, under .15". A more significant chance of showers/storms arrives by late Sunday and Monday as a cool frontal boundary approaches from the Dakotas.
This is why we stay, this is why we tolerate "character-building" winters, why we muscle through slush and muddle through endless wind chill reports 5 months out of the year. Because we know there is a light at the end of the meteorological tunnel. Well, the light has arrived, plenty of sunlight, enough to drag even the most hardened pessimist out of a midweek stupor. Soak it up, because by the weekend it will start to look and feel more like mid June than mid May. That southerly wind component will eventually dredge up moisture from the Gulf of Mexico - no oil (thank God) but rising dew points, topping 60 by Saturday and Sunday. Yes, within 72 hours neighbors will begin griping about humidity levels, it will feel drippy and sticky, enough fuel to spark a few late-day instability showers and T-storms by Saturday and Sunday. The vast majority of the weekend should be dry, temperatures at or near 80 (5-10 degrees above average for mid May) hazy, murky sun, enough for a respectable tan - or burn.
Friday Thunder? The approach of a (juicy) warm front, marking the leading edge of 80-degree air and higher humidity levels will spark a few random, mostly late-day showers and T-showers Friday. I don't think we'll have the dynamics/instability for a widespread severe weather outbreak, but I get nervous around warm fronts (severe storms, especially tornadoes, are more likely to form along warm frontal boundaries) but on Friday we probably won't have sufficient wind "shear" (twisting/turning winds with altitude) necessary for generic, garden-variety T-storms to mutate into rotating "supercell" thunderstorms, capable of prolonging a warm updraft long enough to whip up large hail or tornadic winds. That said, an umbrella may not be a bad idea as you head out the door Friday.
The weekend looks summer-like, a GREAT weekend for the beach, pool or lake. If we have a few hours of hazy, murky sunshine (likely) we'll see highs in the low 80s, with a dew point at or just above 60, making it feel more like late June than mid May. A few weekend headlines (although, truth be told - it's still pretty early to be going into detail). My best shot with the data at hand:
1). Saturday: sunnier, drier, nicer day - probably dry, although a stray T-shower can't be ruled out, especially far western/northern MN. Winds: SE 10-20. Humidity: moderate. High: 78-83
2). Sunday: less sun, but still partly sunny and windier. A better chance of a late-day T-storm, even in the metro area and the Brainerd Lakes area. Winds: SE 15-25 (gusty). Humidity: high. Hours of rain: 1-3. High: 80-85
3). Monday: Best chance of showers and T-storms, some heavy. Winds: W 5-10. Humidity: high. Hours of rain: 3-5. High: 75-80.
GFS Output. O.K. I don't usually include raw model data for St. Cloud, but I want you to see the same data I'm looking at when pondering the 7-Day Outlook. The GFS is predicting highs near 80 Saturday and Sunday, more like mid or late June. The probability of precipitation (in green) reaches 48% Sunday, 60% by Monday. We look at the TREND of the POPS, there's little doubt it my mind that the chance of scattered T-showers will be higher Sunday than Saturday, with the chance of (a few hours of rain) peaking on Monday with a cool frontal passage.
Severe Nation. According to SPC, the Storm Prediction Center, there were 25 tornado reports Tuesday (as of 10 pm), from near Cheyenne, Wyoming to Dumas, Texas. For all the details, click here.
Tornado Count. After a slow start, the frequency of tornadoes, nationwide, is on a rapid upswing. So far, across the USA, as of May 17 a total of 397 (separate) tornadoes have been observed, compared to a running average of 684 which SHOULD have touched down on the USA as of mid May. More tornado statistics from the SPC are here.
Hail Attack. The hail storm that swept across metro Oklahoma City on May 16 produced baseball size hail. Check out the YouTube video of these monster hailstones hitting this poor guy's swimming pool! Amazing.
Expanding Oil Spill. Check out the latest video clip from NASA's low-orbiting satellite - getting closer to the west coast of Florida. It's probably a matter of days before oil reaches the coastline of Clearwater, St. Petersburg and Sarasota. According to travel agents Florida bookings are already down - people are understandably paranoid about having their soft, sugar-sand beach adventure marred by oil, grease and sludge. I don't even want to consider what might happen when a tropical storm or hurricane passes into the Gulf of Mexico - potentially flammable waves of oil being pushed ashore by hurricane-force gusts? I shudder to think of the consequences if engineers can't find a way to shut down the leaking oil well 5,000 feet beneath the surface of the Gulf.
Paul's SC Times Outlook for St. Cloud and all of central Minnesota
Today: Plenty of warm sun, beautiful. Winds: SE 10-15. High: 77
Wednesday night: Clear to partly cloudy. Low: 52
Thursday: Partly sunny, still dry and pleasantly warm. High: near 80
Friday: More clouds, passing shower or T-shower possible. High: 75
Saturday: Probably the nicer day of the weekend, mix of clouds and sun, breezy (SE 10-20). High: near 80
Sunday: Humid and windier with a chance of scattered T-storms, especially late PM hours. Winds: SE 15-25, choppy on area lakes. High: 82
Monday: Best chance of showers and storms, a few hours of rain, sticky. High: 78
Tuesday: Some sun, still warm and humid. Slight thunder risk. High: 80