Saturday, August 25, 2007

Drying, slowly...

The predicted heavy rain on Wednesday night and Thursday stayed farther south, sparing most of southwest Wisconsin any additional flooding. The rest of southern Wisconsin wasn't so lucky, and several more counties have been declared disaster areas. The rain has moved south of the region for now, so we are slowly drying out. That will be a long process, however. The ground will remain saturated for quite some time, and any rainfall in the next two weeks or more will lead to more rapid run-off problems. This has already happened once. On Friday, up to 1.5 inches of rain fell across the northern Kickapoo River watershed in about four hours. This caused the river at La Farge to rise by more than four feet. Under normal circumstances, this amount of rain in that amount of time would cause the river to rise a few inches, if that. There simply isn't any other place for the water to go right now.

The next chance for rain is Sunday night, as warmer and more moist air begins to flow into the region. Better chances for rain will come late Monday through Tuesday night as a cold front moves across the area. Extreme rainfall totals, like those of last weekend, aren't expected, but any thunderstorms that develop in a moist atmosphere can drop an inch or two of rain in a hurry, and this could cause some renewed flooding problems. This threat will become clearer during the next couple of days.

I have heard many people say that this recent rain and flooding was reminiscent of the flood of July 1951. That idea was confirmed by the National Weather Service today, when they released a list of locations that set 24-hour rainfall records last weekend. One of those locations was La Farge, which received 6.14 inches from 8 a.m. Saturday, August 18th thru 8 a.m. Sunday, August 19th. The old record was 5.50 inches, set July 20-21, 1951.


Thursday, August 23, 2007

Heavy rain threat diminishing

The threat for additional heavy rain and flooding is diminishing. The heaviest rain has stayed well to our south today, and storms have not developed across Iowa as expected. The computer models really have not performed well the past two days, as the expected heavy rain has not materialized across the area. This is probably because there are so many little boundaries and fronts floating around the area, and it is difficult to determine exactly where storms will develop.

Thunderstorms remain in the forecast through Friday, but any heavy rain should be isolated enough that it won't cause too many flooding problems.


More on the way?

Thunderstorms with heavy rain stayed south of the area last night, but the flash flood watch continues through this evening due to the threat of more storms moving across the area later this morning and this afternoon. An area of rain and storms is moving northeast across Iowa, and could reach southern Wisconsin by noon. After that, another complex of storms may develop across southern Iowa and move toward Wisconsin again. This is far from certain, as the atmosphere is so muddled right now that it is difficult to tell how any storm complexes will behave with any degree of certainty.

According to the Hydrometeorological Prediction Center, southwestern Wisconsin is at a moderate to high risk of receiving excessive rainfall today (the kind that can cause flash flooding). Also, the Storm Prediction Center has most of southern Wisconsin under a moderate risk for severe thunderstorms today, mostly in the form of damaging winds. This area is just barely south and east of Vernon County, but does appear to include Crawford, Grant and Richland counties. The rest of western Wisconsin and adjacent parts of Minnesota and Iowa are still under a slight risk.

The ground is still completely saturated and rivers are running high, so any additional rainfall, even an inch, could quickly lead to more flash flooding. Storms may linger into Friday, but the weekend should be dry, with the next chance of rain then arriving by about next Tuesday.


Wednesday, August 22, 2007

Wettest Month Ever

August 2007 is now officially the wettest month on record in La Crosse. Total rainfall for the month so far is 12.22 inches there. In La Farge we have received about 14.73 inches so far. Both of these totals are likely to grow tonight and Thursday.

To put this in perspective, total rainfall for January thru July was 15.23 inches.


More Storms, More Flooding

Severe thunderstorms moved across Vernon County early this morning, causing some widespread wind damage and more flooding. Rainfall amounts were less this time, generally one to three inches, but rainfall rates were higher, and in some places water levels were higher than they were Saturday night. The Kickapoo River at La Farge rose quickly from a level of about 6 feet to 11.4 feet overnight, and has since fallen to about 10.8 feet. There were more washouts on area roads due to the rapid runoff. The ground is fully saturated, and cannot possibly handle any more moisture. More storms and heavy rain are in the forecast for tonight through Thursday night. Storms have already developed over western Iowa, and I'm watching these closely to see if they approach southwestern Wisconsin this afternoon. A flash flood watch is in effect through tomorrow morning.

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Sunday, August 19, 2007

Widespread significant flooding continues

Thunderstorms with heavy rain last night resulted in deadly flash flooding across the region. Rainfall totals were generally 4 to 10 inches, with some isolated higher amounts. There have been 7 confirmed fatalities (5 in Winona County and 2 in Houston County.) The Kickapoo River is above flood stage in La Farge and downstream. It is expected to crest at 12.8 feet later today in La Farge and then fall below flood stage by tomorrow. At Gays Mills, record flooding is predicted, with a crest of 20 feet--higher than the infamous flood of 1978. The Seasbranch dam between Viroqua and Avalanche is reportedly leaking, and residents below that and other dams throughout the county have been told to evacuate. Several towns in Winona and Houston counties in Minnesota have also been evacuated.

Some specific rainfall totals include 6.00 inches in La Farge, 11.75 inches near Stoddard, 10.95 inches near La Crosse, 9.23 inches in Viroqua, 7.86 inches in Viola, 7.17 inches near Westby, 6.40 inches near Valley, and 5.40 inches in Ontario. Follow the link below for the latest rainfall totals and damage reports from the National Weather Service:

The flash flood watch continues through this evening, but may have to be extended in some places. Thunderstorms have once again developed over southern Minnesota, and are poised to move across some of the same areas that got heavy rain and extreme flooding last night.


Monday, August 06, 2007

Too much of a good thing?

The two to four inches of rain that fell on Saturday and Sunday made a sizable dent in the rainfall deficits that had led the development of a moderate drought across the region, but it may end up doing more harm than good in some places. Thunderstorms are expected to develop later tonight and track across some of the same areas that got the most rain over the weekend. A Flash Flood Watch is in effect generally south of the Wisconsin River. There is so much moisture in the air (dewpoints are in the upper 70s across much of Iowa and Illinois) that heavy rain is likely with these storms. This rain is expected to linger through Tuesday, with another round of heavy rain/potentially severe storms on Wednesday. After that, temperatures are forecast to remain above normal through the weekend.

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