Forecast: Major rain event late Wednesday & Thursday?

Update 2:40pm

The latest forecast models coming in indicate the potential for a major rainfall event for parts of southern Minnesota and western Wisconsin, including the Twin Cities metro area.

It now appears at least two waves of rain and thunder may roll in starting Wednesday afternoon. By Thursday night, some areas could be swamped with anywhere from 2" to as much as 4"+ in the wettest scenario. Localized flooding could be an issue by Thursday night into Friday morning.

NWS and modles cranking out at least 2" rainfall for the metro through Thursday.

(Click for bigger image)

The first wave may roll into eastern Minnesota and the Twin Cities anytime after 3pm Wednesday and continue through Wednesday night. The second wave may brew Thursday.

The air to the south of the warm front with this system will be very warm and unstable. There is a risk for thunderstorms, some of which could be severe. The Twin Cities appears to be right on the northern edge of the potential severe risk area.

Enjoy the tranquil weather tonight and early Wednesday, then be ready to batten down the hatches for potentially heavy rain by late Wednesday and Thursday.

PH

Original post 9:00 am

You gotta love September in Minnesota.

We've had several frosty mornings in northeast Minnesota last weekend. Then came Monday.

It started cool, with Octoberish temperature levels in the 50s under a steely sky. It was 52 in the Twin Cities at 5:43am. Okay, that's pretty normal stuff for late September.

That was before the super turbo charged warm front blasted in from Iowa. As skies cleared and the sun popped out Monday afternoon south of the warm front, temperatures shot up anywhere from 10 to 20 degrees in just a few hours.

It hit 90 in Luverne, St. James, Mankato, and Fairmont. The temperature spike continued after sundown, with the Twin Cities reaching the daily high of 80 degrees at 11:37pm!

CLIMATE REPORT

NATIONAL WEATHER SERVICE CHANHASSEN MN

201 AM CDT TUE SEP 21 2010

TEMPERATURE (F)

YESTERDAY

MAXIMUM 80 1137 PM

(Click for bigger image)

I saw a July-like 97 degrees Monday in northern Nebraska and southern South Dakota.

Check out the temperature surge as the front pushed north Monday afternoon.

Overnight rumblers:

As a cool front swept through overnight, a few storms rumbled along with it. Here are some rainfall totals.

Twin Cities Airport .56"

St. Paul .40"

Eden Prairie .17"

There were also a few hail reports and some tree branches down. Hail fell with one particular cell as it crossed from near Twin Cities Airport, into Highland Park and onto Hudson, Wisconsin.

MPX: Hudson [St. Croix Co, WI] law enforcement reports HAIL of marble size (M0.50 INCH) at 01:52 AM CDT -- branches down and power outages reported.

MPX: Mahtomedi [Washington Co, MN] trained spotter reports HAIL of ping pong ball size (M1.50 INCH) at 01:50 AM CDT --

MPX: 2 Sw St Paul [Ramsey Co, MN] trained spotter reports HAIL of ping pong ball size (M1.50 INCH) at 01:45 AM CDT -- in highland park area. spotter indicates a dead tree is down in neighborhood.

MPX: 2 Sw St Paul [Ramsey Co, MN] trained spotter reports HAIL of half dollar size (M1.25 INCH) at 01:40 AM CDT -- in highland park area power also is out.

MPX: 1 E Richfield [Hennepin Co, MN] asos reports HAIL of quarter size (M1.00 INCH) at 01:37 AM CDT -- observed at msp international airport.

Doppler storm total rainfall shows some streaks of 1" rainfall under heavier cells. Doppler tends to estmate a little high when hail is present in cloud towers like the storms overnight.

Heavy rain Thursday:

A strong low pressure system is headed this way Wednesday night and Thursday. This one looks like it will be an efficient ran producer, and most of the southern half of Minnesota could see heavy rain starting Wednesday night and continuing through Thursday.

It looks like some widespread 1" to 2" rainfall totals are likely. There could be some isoletd areas of 3"+ with this potent system.

The weather maps for Thursday have the look of a major low pressure system that would produce a major winter storm if this were December. We can be thankful it's still September and we're looking at an inch or two of rain instead of a foot or more of snow!

Enjoy the sun and mild temps in the lower 70s today!

Weather Lab moves to Target Field tonight:

And wish me luck tonight.

I'll be filling in for Craig Edwards as game day meteorologist for the Minnesota Twins at Target Field tonight. The Twins could clinch the division title tonight if they win and Oakland beats the White Sox.

Tune in to KNOW 91.1FM for my live weathercast from Target Field at about 5:48pm assuming we get all the kinks worked out right.

Go Twins!

PH