Updraft: June 20, 2011 Archive

Excessive rains possible, preview was Saturday evening

Posted at 6:37 AM on June 20, 2011 by Craig Edwards
Filed under: Radar, Rainfall, Record

Watching the radar from the Target Field weather lab on Saturday evening it was clear the heavy rain was setting up over western Wisconsin. Here's a graphic provided by the Chanhassen National Weather Service of the radar estimated rainfall for the event.

Click on image to enlarge. The small purple pixel represents an estimate of around six inches for the period 7am CDT Saturday to 7am CDT on Sunday

Eau Claire Airport reported 4.74 inches of rain on Saturday evening. LaCrosse measured 4.50 inches. Both of these totals were daily records.

A meteorological summary of the deluge has been posted on the NWS Chanhassen website. See details.

Thankfully we were able to salvage a pretty decent Sunday. This upcoming week, particularly the next three days will be soggy at the least and perhaps downright dangerously wet in some locations.

A very slow moving, spring-like weather system will track through the upper Midwest. The snail pace from west to east will place Minnesota, as well as the eastern Dakotas and western Wisconsin in a prime region for heavy rainfall.

Here's NOAA's Environmental Prediction Center's estimate for rainfall accumulations in the next seventy-two hours.

This graphic gives a general sense of the most likely region for heavy rain. Isolated totals similar to Saturday evening's rain in western Wisconsin are very possible.

Have time to probe beneath the headlines? Here's a great link on the meteorologist's insight on the upcoming heavy rainfall, courtesy of the National Weather Service in Chanhassen.

After enduring this drenching, we can look forward to the prospects of some warmer and drier weather next week. Here's the Climate Prediction Center's temperature outlook for the next eight to fourteen days. Odds favor above normal temperatures.

The Climate Prediction Center's precipitation outlook for the period June 27 to July 3rd, indicates the odds favor less than normal precipitation in our neck of the woods.

By the way the radar is already lit-up in Iowa and far southern Minnesota this morning. The deluge is at hand.
CE

Overnight rain & thunder; 2" to 3+" totals by Wednesday

Posted at 4:49 PM on June 20, 2011 by Paul Huttner (1 Comments)
Filed under: Rainfall

Get ready for another good soaking. At least this one will come during the week.

The system:

An unseasonably strong and (slow moving) low pressure system is spinning out of the Rockies into Minnesota this week. The system will send several waves of showers, and a big "straitform rain" shield into Minnesota tonight through Wednesday.

Storng surface low pressure and a warm front moving north.

The system is unusual for June in that it looks more like a springtime weather system on the maps, featuring a large, widespread "wrap around" rain shield and a tight pressure gradient which will generate a steady northeast wind. Late June

Flood watches are in effect for much of southern Minnesota.

Timing:

Bands of rainfall will increase and spread north into Minnesota today, tonight and Tuesday. It looks like the heaviest bands of rain will comer after midnight tonight and through Tuesday. The system may linger through Wednesday and into Thursday in some areas.

Models bring rain in early Tuesday through at least Wednesday.

It looks like the bulk of the heavy rain will come in after midnight into early Tuesday morning in the metro.

-Latest Twin Cities radar loop

Rainfall totals:

This one looks like another super soaker, with the potential to cause some flooding in some areas. Rainfall totals could easily exceed 2" to 3" in much of Minnesota over the next 72 hours.

The NAM model is cranking out 2.5" of rainfall at MSP by late Wednesday!

Tropical connection:

This massive weather system is pulling in a moisture plume from the tropical Pacific Ocean.

GOES water vapor image shows tropical moisture plume feeding into low pressure over Kansas.

When this happens in mid-latitude cyclones the additional injection of moisture can "supercharge" moisture, and that can lead to tropical downpours with enhanced rainfall totals of several inches.

Severe risk?

It looks like the biggest risk for severe storms will be south through tonight. A moderate risk for severe weather extends through western Iowa to the Minnesota border.

Lake Minnetonka water discharge into Minnehaha Creek reduced in advance of potential flooding rains:

MCWD has reduced the flow from the Gray's Bay Dam on Lake Minnetonka into Minnehaha Creek to help reduce flood risk along the creek. The story here.

"The Minnehaha Creek Watershed District controls the headwaters structure at Minnetonka's Grays Bay, the outlet of Lake Minnetonka to Minnehaha Creek. And according to MCWD, the discharge at Lake Minnetonka's Grays Bay Dam was reduced to 50 cubic feet per second earlier today, in order to build capacity in Minnehaha Creek for the rainfall expected this week.

On June 20, the lake level of Lake Minnetonka (Lake Minnetonka's elevation above sea level), as measured at Minnetonka's Grays Bay, was 929.65 feet. That's just above the lake's ordinary high water level of 929.40 feet. To reduce flooding on Lake Minnetonka, the MCWD tries to keep the lake level stabilized between 928.60 and 929.40 feet."

Want some good news? Right now at least, it looks like we could dry out and see the sun return Friday and into the weekend. There may be a chance of more rain by Sunday.

Stay tuned as we track the rain the next few days!

PH

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