Monday, July 20, 2009

Minnesota Rainfall Deficit, Extreme in Spots!

Todd's Outlook

Today: Lingering showers and T-storms early, then partial clearing. High: 78

Tonight: Mostly cloudy, a shower or storm still possible. Low: 61

Wednesday: Mix of clouds and sunshine, warmer. High: 82

Thursday: Plenty of sunshine, a nice dose of summer! High: 85

Friday: Ample sun, chance of late-day T-showers. High: 84

Saturday: Cooler under a partly sunny sky. T-storms possible far southern MN. High: 79

Sunday: Mostly cloudy with showers, windy and cool again. High: 75

Monday: Stalled pattern once more....Mostly cloudy and showery, a damp wind. High: 72

I'm amazed by the lack of moisture and warm air this summer and especially this July. Take a look at the image above - it shows a low or a storm system just east of the Hudson Bay, which has been continually rotating cool air down through the Great Lakes. The warmer the air is, the more moisture it can hold, meaning that our lack of rain can be (somewhat) correlated to the cooler weather this summer. The jet stream, or the strong upper level winds are consistently staying to our west and south, which is the main highway for showers and thunderstorms. The dome of hot air is also holding firm across the western half of the country with record high temperatures being set nearly everyday. When will this pattern break? Extended models are showing a break in the cool weather across Minnesota by the end of the month. Upper 80's to low 90's may be possible again by then, stay tuned!

Below the latest U.S. Drought Monitor, which was released Thursday, July 16th. (The Drought monitor releases a new map every Thursday) Notice how most of the Twin Cities Metro is included in the SEVERE DROUGHT. 73% of the state is considered to be either abnormally dry or in a drought.

As of 6pm Monday evening: The precipitation departure from normal since January 1st, from climate reporting stations around the state, stood like this:

Twin Cities: -7.85" Below Normal
Duluth: -4.45" Below Normal
Rochester: -4.43" Below Normal
St. Cloud: -0.70" Below Normal
International Falls: +0.80" Above Normal

Radar imagery from Monday evening showed a wall of water across northwestern Minnesota. This activity developed along a cool front that will slowly move eastward on Tuesday and may produce some fairly substantial rainfall across parts of the state. The image below shows the best guess at accumulated rainfall from 6pm Monday evening through 6pm Tuesday evening. The "X" and the numerical value (near Duluth, MN) is the largest value the weather model prints out during that time period for Minnesota. Central Minnesota will likely receive around 0.25" with some 0.50" to 1.00" amounts possible in convective showers (thunderstorms).

Think rain! Hopefully when you check your rain gauge Tuesday evening, you'll be pleased.

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