The F Word - Frost

Patchy frost will hit northern Minnesota and northern Wisconsin this weekend as an upper low crosses Lake Superior, forecasts Allen Motew of QT Weather. On Saturday cold air moves in with temperatures in the low 40’s reaching from the Dakotas to N Iowa (early Sunday morning expect a low of 34 F at International Falls, MN), he says.

Watch out for patchy frost levels on Sunday night in N Wisconsin with 39F in Rhinelander, WI and 37F at Duluth, MN (note the 33F for International Falls, MN), he adds.

Monday sees temperatures as much as -12 degrees below normal in Illinois, Michigan and Indiana further limiting the number of growing degree days, says Allen.

Slightly further ahead weather forecast models are now showing a hard freeze moving into the Canadian Prairie for Sept 6-8. Previous model runs had only been “hinting” at such an occurrence. This coincides with the next full moon cycle of between September 4 and 11, mentioned yesterday as the first serious 'killing frost' threat of the season.

This latest “colder scenario” begins Sunday Sept 6 as a low crosses central Canada with frigid air dropping southward across the Canadian Prairies. On Tuesday Sept 8, rain breaks out in the Corn Belt along the leading edge of the frigid Canadian intrusion. On Wednesday Sept 9 a second cold air outbreak is “pulled” south into South Dakota and Nebraska behind a low-pressure center in Illinois, he adds.

The cool and rainy Midwest weather expected over the next several days will not only hamper crop ripening but also encourages the spread of disease, warns Gail Martell of Martell Crop Projections.

Rainy weather has developed along a narrow front in the Midwest over the past 48 hours producing areas of heavy rainfall. Conditions are perfect for the development of white mold and fungus that causes sudden death syndrome in soybeans. Increasingly, reports of declining soybean conditions are being reported on agriculture websites, she adds.

White mold and SDS were widespread in Minnesota in 2004, driving the crop yield down sharply aftre a very wet August-September encouraged widespread fungus disease in that state, she concludes.

WGN-TV Chief Meteorologist Tom Skilling says that this year's Chicago summer is on track to become the cloudiest there since sunshine data began in 1894.

Heavy late Thursday storms also drenched eastern Iowa Thursday. In New London, just across the Illinois line in southeast Iowa's Henry County, 8.34 inches fell - 7.20 inches of it in just four hours. That's equivalent to receiving a fifth of Chicago's annual precipitation in that short period of time.

These forecasts certainly seem to be indicating that there are some serious weather threats developing, and that is maybe why the market is attempting to add a bit of risk premium just at the moment.

It appears that we are in for another season of hugely variable yields, whilst weather conditions have been close to ideal in some areas other locations have suffered from far too wet and cool throughout much of the growing season.