Unprecedented: Rare May snowfall could break records; Rain to snow today

Headlines:

3.0" all time May snowfall record for Twin Cities

-Rain mixes with..then changes to all snow in the metro later this PM & evening.

-Snowfall coverage and intensity picks up tonight

-Overall metro snowfall range looks highly variable, less west & heavier east

-Snowfall range of 2" to 6"+ (heaviest east metro) is likely by noon Thursday

-Morning model runs suggest some 6" to 12" totals possible in a narrow band southeast of the Twin Cities from near Owatonna to Red Wing & Hastings to Menomonie and northward toward Rice lake & Hayward.

-Snow tapers off from west to east Thursday AM

"Expect The Unprecedented"

I've used that tag line recently in broadcasts and for some of my talks about climate change to groups in Minnesota. It seems to fit like a glove this week.

We are on the cusp of what still looks like a rare, even unprecedented May snowfall event in Minnesota.

Radars are lighting up as snow is already flying west, and the dreaded "rain-snow line" will move east through the metro as the day wears on.

By tonight your almost green lawn will once again turn a shade of white, and moderate to heavy snow will accumulate.

In this Updraft we move past the latest bout of "weather denial" to and count up the inches in what could be a record breaker for the Twin Cities.

Is it June yet?

Nuts & Bolts: Latest on incoming winter storm

Winter Storm Warnings are flying once again for the metro. The latest version paints a swath from Albert Lea through the Twin Cities to Rice Lake and Hayward.

Here's the verbiage from the Twin Cities NWS.

INCLUDING THE CITIES OF...CENTER CITY...MINNEAPOLIS...BLAINE...

ST. PAUL...STILLWATER...GAYLORD...CHASKA...SHAKOPEE...

BURNSVILLE...NEW ULM...ST. PETER...LE SUEUR...FARIBAULT...

RED WING...ST. JAMES...MANKATO...WASECA...OWATONNA...FAIRMONT...

BLUE EARTH...ALBERT LEA...AMERY...BALSAM LAKE...RICE LAKE...

BARRON...LADYSMITH...HUDSON...NEW RICHMOND...RIVER FALLS...

PRESCOTT...MENOMONIE...BOYCEVILLE

354 AM CDT WED MAY 1 2013

...WINTER STORM WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO 7 PM CDT THURSDAY...

THE NATIONAL WEATHER SERVICE IN TWIN CITIES/CHANHASSEN HAS ISSUED A WINTER STORM WARNING FOR HEAVY SNOW...WHICH IS IN EFFECT FROM 3 PM THIS AFTERNOON TO 7 PM CDT THURSDAY.

* TIMING: RAIN THIS MORNING WILL TRANSITION OVER TO SNOW BY MID AFTERNOON. SNOW WILL THEN CONTINUE IN PERIODIC BANDS THROUGH TONIGHT AND TAPER OFF DURING THE DAY THURSDAY. SNOW MAY BE HEAVY AT TIMES THIS EVENING THROUGH THE EARLY MORNING HOURS.

* SNOW ACCUMULATION: 6 TO 9 INCHES.

* OTHER IMPACTS: RAPID SNOW ACCUMULATION MAY QUICKLY MAKE TRAVEL HAZARDOUS.

Some of you have noticed NWS still issues many of their advisories in ALL CAPS. Maybe they "yell" on the internets to block out the sound of everyone yelling back as the next winter storm warning is posted...in May.

It pays to have a sense of humor in Minnesota.

Relatively narrow band of heavy snowfall?

This time it looks like the south & east metro may win the snow lottery.

The best lift and moisture...and heaviest snow band seems to be setting up either side of a Fairmont-Owatonna-Red Wing-Menomonie-Rice Lake-Hayward line tonight.

I'm not sure I buy the overall metro range of 6"-9" of snow just yet. It looks like the heaviest band of 6"+ snowfall potential should be relatively narrow and favor the east metro....and there are indications snowfall totals may drop off dramatically in the west & northwest metro...where only 1" to 3" may fall.

The NAM model lays out the tight "snowfall gradient" which favors higher totals in the east metro...with snowfall dropping off quickly as you move toward the northwest metro.

The overnight GFS & NAM runs backed off projected snowfall totals considerably...from well over 6" for MSP Airport into the 2" to 4" range. That may be a reflection on the trend to shift the heaviest bands slightly east...and not on overall snowfall intensity. There is always run to run variability...but let's see what the next set of model runs brings.

The Euro model "meteogram" show the change from rain to snow today in the metro.

Up North: 6" to 12" possible

The same story plays out in Duluth and northwest Wisconsin tonight. The Duluth NWS highlights the heaviest snowfall...up to 12" in northwest Wisconsin with totals rapidly dropping as you move west toward Duluth.

Time to run the Birkebeiner in May?

Record breaking May snowfall event?

It will only take 3.1" to break the all time May snowfall record for the Twin Cities.

Snow at Cross Lutheran Church, (Present Day Maplewood)

May 12, 1946

Courtesy the Maplewood Area Historical Society

Here's what the Minnesota Climate Working Group has to say about rare May snowfall events.

Snow that falls in May is typically a novelty. The ground is usually too warm by May to allow much of an accumulation. Looking at past records for the Twin Cities, a trace of snow falls during the month of May fairly frequently, with the last windswept flurries reported on May 1-2, 2005. If the snow manages to accumulate it is generally under an inch and mostly on grassy surfaces. The most recent measureable Twin Cities snow event was 0.3 inches on May 5, 1991.

About once every 30 years or so, there is a snow event that is enough to cover newly greened lawns and coat budding leaves. The last time there was a snow event in May greater than an inch in the Twin Cities was on May 2, 1976 with 1.2 inches. The most that it has snowed in May in a single event for the Twin Cities is three inches. This has happened on three occasions: May 20, 1892, May 1, 1935 and May 11-12, 1946.

Bottom Line: Rain will change to snow today from west to east. Snow will be moderate to heavy at times through tonight.

Snowfall rates could reach 1" to 2" per hour tonight.

Overall metro snowfall accumulations of between 2" and 6"+ are likely by midday Thursday. Some 6"+ totals are possible, especially in the east metro. This morning's model runs suggest some 6" to 12" totals possible in a narrow band southeast of the Twin Cities from near Owatonna to Red Wing & Hastings to Menomonie and northward toward Rice lake & Hayward.

PM rush hour should be sloppy today, but temps will fall below freezing tonight and that could mean an icy commute Thursday AM.

Stay tuned as we tweak the totals and coverage today.

Paul Huttner