Rainy start for October

Updated at 2:00 p.m. Sunday

The Storm Prediction Center has updated the severe weather outlook for Monday to shift the marginal risk area a bit to the southwest. This change removes the Arrowhead north of Duluth from the risk area Monday afternoon and evening.

The following is my original Updraft blog from Sunday morning.

September

September was unusually dry for much of Minnesota. MSP Airport, the official weather station for the Twin Cities, recorded just 1.04 inches of rain during the month. That is about two inches less than normal. The National Weather Service Office in Chanhassen measured more than twice that amount at 2.18 inches. My rain gauge in Minneapolis got 1.20 inches.

Many areas farther north picked up greater amounts of rain. St. Cloud recorded 2.93 inches while 3.55 inches was the total for Duluth.

Soggy start to a 3-day event

Abundant moisture has been surging our way from the southwest. Rain began falling early Sunday morning and we will continue to experience periods of wetness though Tuesday.

That's the big picture. Now let's fine tune the forecast.

Widespread rain, some of it heavy, has been falling on western Minnesota and is spreading into the northern part of the state. Showers around the Twin Cities diminished as start time for the Twin Cities Marathon approached at 8 a.m., but more rain is on its way from the southwest to maybe catch up to slower runners before they reach the finish line in St. Paul.

The heavy rain in western and then northern Minnesota will taper off as we get later into Sunday, but some heavier showers and maybe a thunderstorm are likely to approach the metro area this afternoon.

High temperatures will have a rather narrow range from the upper 50s in the far north to the mid 60s.

Look for gusty winds from the southeast at 15 to 30 mph across the metro area this afternoon.

Rain and more rain

Widespread periods of rain will continue tonight and on Monday. Forecast models indicate that the Twin Cities area will have a chance of thunderstorms early Monday morning and then again beginning in the afternoon. Heavy rain is possible.

Afternoon high temperatures on Monday will be in the 60s for much of Minnesota but places south of the Twin Cities such as Mankato, Faribault, Red Wing, Rochester and Winona are likely to warm well into the 70s.

Severe storms in Minnesota in October?

In an unusual pattern for October , we have a chance of strong or even severe thunderstorms with hail later Monday afternoon and evening. The risk category is marginal, which is the lowest category of risk and is shown in the darker green below. The lighter shade of green represents forecast areas of non-severe thunderstorms.

Then more rain

Yet more rain is likely Monday night and on Tuesday, but probably not for all of us. Forecast models have been indicating the likelihood of a rather narrow band of heavy rain to develop across southwest to northeast Minnesota Monday night. Here is how the North American Mesoscale Model (NAM) portrays the 3-hour rainfall ending at 4 a.m. on Tuesday:

How much rain?

Once the rain gauges have done their work and the numbers have been added up, from one to maybe three inches of rain is likely to have fallen on a significant area. Southeastern Minnesota might get by with less than an inch.

Tropical update

I am pleased to report that there are no hurricanes in the offing. There are not even any disturbances threatening to develop into tropical storms or hurricanes.

But there is one disturbance, marked by the yellow "X" below, that has been marching up Florida.

Although it has a zero-percent chance of developing into a tropical storm, it has been producing gale force winds and heavy rain in Florida. Jacksonville, in the northeastern corner of Florida, has received 3 inches of rain in the past 24 hours with more on the way.