Thursday, May 21, 2009

Holiday weekend weather: batting .600

(Update: 2:07 pm). Mostly good news on the weather front. I've just had a look at the latest models and the weekend weather still appears to be mostly-promising, with a few notable exceptions. Doppler showers moderate showers over far southern MN, near the Iowa border. This band of rain will drift slowly north, but most puddles should remain south of the Minnesota River into the evening hours. A reinforcing bubble of Canadian high pressure will suppress most of the showers/T-storms just to our south through most of Sunday. Saturday and Sunday still appear to be the nicer, sunnier, drier days of the weekend. By Memorial Day a northbound warm front will spark more organized showers and heavier thunderstorms, in fact it may rain a fair amount of the day over far northern and western Minnesota, including the lakes district. Definitely have a plan B (inside) for Monday, as much as .5 to 1" of rain may fall from Windom to Little Falls, Cross Lake, Leech Lake and the MN Arrowhead (Monday temperatures in the 50s to low 60s far north). So 2 out of 3 days look pretty nice; we're batting .600. Not bad for the first holiday of summer.

Memorial Weekend Outlook
. Click on the map to get a higher-resolution, full-screen prediction of holiday weekend rainfall. As you can see, the best chance of showers and storms will come over the southern quarter of Minnesota, generally south of a line from Windom and Willmar to Northfield and Wabasha. Extreme southern MN may pick up 1"+ of rain over the weekend. Any showers over far northern MN are forecast to be light and spotty, with a big patch of relatively dry weather predicted for most central and northern towns (and lakes). The overall pattern makes me nervous: that much moisture lurking JUST to our south. A slight shift in the storm track could bring that plume of moderate/heavy rain into farther north, into the Twin Cities - St. Cloud corridor, possibly even reaching the Brainerd and Detroit Lakes area. I think this (GFS) model is underestimating the rainfall potential for the northern half of Minnesota. I still envision a period of showers and T-storms, especially from Sunday night into Memorial Day. That said, odds favor dry weather for most of the holiday weekend.

To get the very latest 75 hour rainfall predictions (showing the total rainfall expected during this period) click here.

Holiday Highlights:

* Today: sunny start but clouds increase, slight chance of a shower/T-storm by late afternoon as a weak, reinforcing cool front arrives
* Best day for outdoor plans: Saturday. High pressure hangs on long enough for sun most of the day.
* Warmest day: Sunday. A southeasterly breeze will tug the mercury well into the 70s locally, even up north from Brainerd and Cross Lake to Wadena and Leech Lake...probably the best day to test out the lake water. Yes, it's still chilly water: plan on water temps. in the 55-63 degree range, depending on the depth of the water on your favorite lake. I predict you won't want to be in the water for long!
* Jacket weather: take a sweatshirt or jacket. Under the center of a Canadian bubble of high pressure temperatures may dip into the low 40s, even some upper 30s over the northern half o Minnesota late Saturday night. Sunday morning will start out chilly!
* Worst day: Memorial Day. A few hours of showers and T-storms seem likely, not an all-day washout, but if you have plans for Monday do have a Plan B (indoors) and be ready to make a mad dash to the cabin or garage!
* High Temperatures: close to average for late May. Near 70 Saturday afternoon, mid to upper 70s Sunday, but cooler 60s (north) Monday as showers and storms cool things down a bit.
* Winds: generally blowing from the east/southeast on Saturday (10-15 mph with higher gusts), south to southeast on Sunday. Monday winds start out blowing from the southeast, then shift to the west/southwest behind a weak frontal boundary.
* Barometer: falling steadily throughout the weekend, potentially good news for fishing. Throw in increasing clouds and a walleye "chop" and the best fishing weather may come Sunday evening through Monday morning. Good luck out there.
* Visibility: best on Saturday, nearly unlimited (25 mile plus) visibility. Visibilities start to drop off late Sunday, dropping under 1-2 miles in showers, T-storms on Memorial Day.

Paul's Outlook

Friday: Plenty of sun, lukewarm and pleasant. There is a slight chance of a late-afternoon or evening shower/T-storm. Winds: South 5-15. High: 71

Friday night: Spotty showers weaken and drift into Wisconsin. Slow clearing. Low: 47

Saturday: Nicest day of the holiday. Mostly sunny and pleasant! Winds: East 5-15. High: 72

Saturday night: Clear, bordering on chilly. Low: 41 (30s expected for the northern lakes).

Sunday: Mildest day? Sun much of the day, clouds increase during the afternoon. Winds: Southeast 10-20. High: 77

Memorial Day: Mostly cloudy, unsettled, more humid with a few hours of showers, possible T-storms. Winds: SE/SW 10-15. High: near 72, then cooling down into the 60s.

Tuesday: Damp start, then gradual clearing, getting better. High: 68

Wednesday: Sunny and milder. High: 75

Thursday: Lingering sun, not too many complaints. High: 77

According to the U.S. Drought Monitor much of southeastern Minnesota is in a moderate drought, so in spite of the lousy timing it's pretty hard to get indignant about rain in the forecast. Southern Washington County, south of Stillwater is in a severe drought, and conditions get even worse as you cross the St. Croix River into Wisconsin. Across the rest of central and northern Minnesota soil moisture is in pretty good shape and farmers are optimistic about the potential for a solid harvest later in the year. According to Pete Boulay at the State Climatology Office the Twin Cities metro area is running nearly a 5" rainfall deficit so far in 2009. If you go back until the beginning of 2008 that rainfall shortage is closer to 10". So no, a nice, steady rain would probably qualify as a "good forecast", at least from the Twin Cities on south and east toward the Mississippi.

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