Unprecedented: 18″; All time May MN snowfall records fall; 70s return next week

Expect The Unprecedented

Minnesota should have our own weather reality show.

We did it again.

Our latest "Extreme Minnesota Weather Event" has smashed yet another all time monthly Minnesota state weather record.

18"...a cool foot and a half in Blooming Prairie on May 2nd?

The Minnesota Climate Working group is still digging out from the blizzard snowfall of reports, but they believe this is the biggest snowfall ever recorded in the month of May in Minnesota.

Did I mention it's... May?

Digging out from 15.5" in Owatonna

Image courtesy Larry Keltto

Prolific Totals:

This would be a big headline storm for January or March....but for May 2nd it;s downright record smashing.

Here's the map...and the latest set of totals from the Twin Cities NWS.

Image: Twin Cities NWS

PUBLIC INFORMATION STATEMENT

NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN

145 PM CDT THU MAY 02 2013

...SNOWFALL TOTALS FROM MAY 1ST AND 2ND SNOWFALL EVENT...

SNOW REPORTS LISTED BY AMOUNT

INCHES LOCATION ST COUNTY TIME

------ ----------------------- -- -------------- -------

18.00 BLOOMING PRAIRIE MN STEELE 1145 AM

17.00 RICE LAKE WI BARRON 0130 PM

16.00 1 NE CAMERON WI BARRON 1200 PM

15.50 2 E OWATONNA MN STEELE 0730 AM

15.00 SW ELLENDALE MN STEELE 0800 AM

14.70 BALDWIN WI ST. CROIX 0743 AM

14.00 5 NE RICE LAKE WI BARRON 0115 PM

14.00 3 NW SPRING VALLEY WI ST. CROIX 1010 AM

14.00 3 NNW MAIDEN ROCK WI PIERCE 0936 AM

14.00 BARRON WI BARRON 0754 AM

14.00 ELLSWORTH WI PIERCE 0540 AM

13.50 PINE ISLAND MN GOODHUE 1130 AM

13.50 4 SE RED WING MN GOODHUE 0800 AM

13.30 CHETEK WI BARRON 0130 PM

13.00 BARRON WI BARRON 1043 AM

12.50 3 NNW NERSTRAND MN RICE 0830 AM

12.00 HAMMOND WI ST. CROIX 1100 AM

12.00 BLOOMER WI CHIPPEWA 1100 AM

12.00 MENOMONIE WI DUNN 1015 AM

12.00 HAUGEN WI BARRON 0815 AM

12.00 5 NE RICE LAKE WI BARRON 0815 AM

12.00 STOCKHOLM WI PEPIN 0800 AM

11.50 CLEAR LAKE WI POLK 0751 AM

11.50 CONGER MN FREEBORN 0553 AM

11.20 4 E NERSTRAND MN GOODHUE 0800 AM

11.00 1 W ROBERTS WI ST. CROIX 1130 AM

11.00 WELLS MN FARIBAULT 0729 AM

10.80 RIDGELAND WI DUNN 1200 PM

10.80 5 NE WHEELER WI DUNN 0855 AM

10.50 BOYCEVILLE WI DUNN 0823 AM

10.00 ELK MOUND WI DUNN 1200 PM

10.00 1 SSW RIVER FALLS WI PIERCE 0800 AM

10.00 WELLS MN FARIBAULT 0800 AM

10.00 RED WING MN GOODHUE 0757 AM

10.00 BRICELYN MN FARIBAULT 0729 AM

10.00 WASECA MN WASECA 0729 AM

10.00 RIVER FALLS WI PIERCE 0700 AM

10.00 ALBERT LEA MN FREEBORN 0529 AM

9.30 BLOOMER WI CHIPPEWA 0130 PM

9.00 4 ESE CLAYTON WI BARRON 1200 PM

9.00 2 W DURAND WI PEPIN 1000 AM

9.00 COLFAX WI DUNN 0815 AM

9.00 WASECA MN WASECA 0800 AM

9.00 4 NW ARKANSAW WI PEPIN 0745 AM

9.00 1 S HUDSON WI ST. CROIX 0733 AM

9.00 1 SW BOYCEVILLE WI DUNN 0643 AM

8.50 4 S ISLAND LAKE WI CHIPPEWA 0913 AM

8.50 12 N BRUCE WI RUSK 0140 PM

8.40 ZUMBROTA MN GOODHUE 0700 AM

8.40 HASTINGS MN DAKOTA 0510 AM

8.30 5 S FARMINGTON MN DAKOTA 0554 AM

8.20 CANNON FALLS MN GOODHUE 0813 AM

8.20 3 SSE HAMPTON MN DAKOTA 0700 AM

8.00 9 NE WHEELER WI DUNN 1030 AM

8.00 2 SE COTTAGE GROVE MN WASHINGTON 0510 AM

7.80 HASTINGS MN DAKOTA 1130 AM

Snow smashed car in Faribault.

Image courtesy Audrey Kletscher Helbling

Record Storm: All time Minnesota may snowfall record falls

It looks like the 15" to 18" totals in Minnesota have smashed the all time Minnesota state record for snowfall in May.

The Minnesota Climate Working Group expands.

Historic Snow Storm - Southeast Minnesota: May 1-2, 2013

Overview

Over one foot of snow fell on southeast Minnesota on May 1 and 2. The storm snarled roads, closed or delayed schools, and downed power lines. Daily and monthly snowfall records were set in numerous locations. Final data are still to be evaluated, however, it appears likely that the event will go into the record books as depositing Minnesota's heaviest May snowfall totals ever.

Heavy May snow was reported in Iowa, Wisconsin, and Minnesota. In Minnesota, the heaviest of the snowfall totals topped 14 inches in Steele, Dodge, Olmsted, Goodhue, and Wabasha counties. Snowfall totals in excess of eight inches were reported in Faribault, Freeborn, Mower, Waseca, Rice, Dakota, Washington, and Winona counties.

While May snowfalls are not uncommon in northern Minnesota, heavy May snowfall in southern Minnesota is rare. A quick scan of all historical Minnesota May daily snowfall totals greater than or equal to 3.0 inches indicates that May 1938 may have been the last time any southern Minnesota observer reported snowfall totals of similar magnitude.

Minnesota's record state daily May snowfall total is 12.0 inches. This threshold was reached three times: May 17, 1890 in St. Cloud, May 8, 1938 in Windom (Cottonwood County), and May 3, 1954 near Leonard (Clearwater County). It is likely that a new record will emerge from the May 2013 storm.

Our delayed spring may have provided an unlikely benefit. During a typical spring, leaves on southeast Minnesota trees are fairly well developed by this time. The additional leaf area would have captured more snow, creating more strain on branches, and perhaps amplifying the impact of downed limbs on power lines.

Bizarre and unusual storm:

This was not your typical Minnesota snowstorm.

Several factors lead to an extremely narrow, elongated band of intense snowfall with this system.

1) "Blocking Pattern" = stalled storm

A blocking pattern in the jet stream caused the storm to stall right over eastern Minnesota as a "cut-off" low developed in the Southern Plains.

Image: NOAA

The high pressure "block" over the eastern USA produced a "stuck" weather pattern, which kept heavy snowfall over the same area for more than 24 hours.

2) "Elongated" taffy-stretched storm system

The unusual block produced a stretched out "elongated" storm system with an impressive moisture feed from the Gulf of Mexico. That focused intense snowfall in a very narrow band...only 1-2 counties wide in most places.

Image: College of DuPage Weather Lab

3) "Dynamic Cooling" & lack of cold air "advection" behind storm

Meteorology 101: You need a feed of cold air into most winter storms to intensify the system and produce heavy snowfall totals.

Apparently this system didn't get that memo.

This "out of season" May snow event meant temperatures in the 40s behind the storm. It was actually warmer behind the storm than underneath the precipitation shield...where temps hovered in the 30s, just marginally cold enough for snow.

Image: College of DuPage Weather Lab

The cold air in this storm came from above. Intense downdrafts with heavy snowfall pushed sub-freezing air in the 30s down toward ground level from 5,000 to 10,000 feet and higher.

4) Razor Sharp Cutoff: Dry air erodes western edge of snow shield

Typically snowstorms in Minnesota exhibit a gradual reduction in intensity of snowfall on the back side of the storm.

But a strong push of dry air on the system's backside eroded the western edge of snowfall.

Image: WxUnderground

That's why it was snowing in the southeast metro...and you could drive a block to the west and not see a flake.

Remarkable.

Up Next: "Retrograde" swings snow and rain backwards into Minnesota

Usually when storms move through they are carried off to the east by the jet stream.

Not this time.

Our record producing, stuck & blocked weather pattern and cut-off low will spin moisture back into Minnesota from the east Friday.

The good news? What may start as some wet snow early will change to all rain as warmer air feeds into the system.

Spring Returns: 70s ahead again next week

Spring like temps will finally return again next week...as this unusual late season pattern returns closer to "normal."

Image: NOAA via Iowa State University

At this point many Minnesotans say "Bring it on!"

PH