Saturday’s snow storm unique in many ways

I spent the morning looking ahead at Thanksgiving week.

I find myself spending the afternoon looking back at last weekend's amazing snow storm.

10" of fresh snow coats the weather lab deck rail last Saturday.

Saturday's early season snow system was unique in several aspects. The Twin Cities NWS put out an excellent review here, but I think the system is worth another close look.

-From a thermal perspective it was a "Goldilocks Storm"...not too warm, not too cold...just right for generating heavy snow. Temperatures in the critical lowest mile of the atmosphere were just below freezing...perfect for generating big, rapidly accumulating snowflakes. (Stellar dendrites)

Morphology diagram shows snowflake types favored at different temperatures. Image courtesy of snowcrystals.com.

(Click to enlarge)

-The heavy snow band was remarkably narrow. In some places in northern Iowa the area accumulating 6" or more was only about 30 miles wide! Along I-90 in southern Minnesota the storm laid down only about an inch in Worthington and Albert Lea...and dumped around 10" in between at Fairmont.

Twin Cities NWS snowfall totals from Saturday's "narrow" snow band.

Even in the southeast Twin Cities metro area snowfall totals ranged from around an inch to over 6" in just a few miles.

Now you know why forecasters can get white knuckled about a mere 30 mile shift in the storm track!

-The storm was a classic "comma shape" system on the satellite loop. This is how you draw them up in the weather textbooks.

-The surface low track was ideal for heavy snow in the west metro. The low tracked from eastern Iowa into western Wisconsin Saturday.

-The storm generated significant lift or "upward vertical velocity" at its peak early Saturday. This caused small thunderstorms to develop near the storm's core, generating "thundersnow" or convective snow bursts. Snowfall rates reached 2" per hour early Saturday morning near the Twin Cities in these convective snow bands.

From a climatological standpoint, the storm packed rare potency for a pre-Thanksgiving system in Minnesota. (Data confirmed by Twin Cities NWS)

-Snowfall total of 8.0" was officially observed at the Minneapolis/St. Paul International Airport

-This was the largest pre-Thanksgiving, as well as November snowfall, for the Twin Cities since the "Halloween Blizzard" of October 31-November 2, 1991.

-Since 1997, this was only the third six inch or greater official snowfall in the Twin Cities during meteorological autumn (Sept-Nov)

PUBLIC INFORMATION STATEMENT

NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN

110 AM CST MON NOV 15 2010

...SNOWFALL REPORTS FROM THE NOVEMBER 13TH WINTER STORM...

LOW PRESSURE DEEPENED AS IT MOVED FROM CENTRAL IOWA EARLY ON THE

13TH TO NORTHERN WISCONSIN BY EARLY ON THE 14TH. THIS FAVORED

WIDESPREAD PRECIPITATION ACROSS MUCH OF MINNESOTA AND WISCONSIN.

ATMOSPHERIC TEMPERATURES WERE COLD ENOUGH FOR THIS TO BE SNOWFALL

ACROSS MUCH OF MINNESOTA...AND WAS THE FIRST SIGNIFICANT

ACCUMULATION OF THE SEASON FOR CENTRAL AND SOUTHERN MINNESOTA AND

NORTHWEST WISCONSIN.

THE TOTALS BELOW ARE SEPARATED BY AMOUNT...AND ARE NOT NECESSARILY

THE FINAL AMOUNT FOR EACH LOCATION.

SNOW REPORTS LISTED BY AMOUNT

INCHES LOCATION ST COUNTY TIME

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

12.00 3 WSW MAPLE GROVE MN HENNEPIN 1111 PM

11.00 WINNEBAGO MN FARIBAULT 0700 AM

11.00 EDEN PRAIRIE MN HENNEPIN 1030 AM

11.00 1 SSW WYOMING MN CHISAGO 0400 PM

10.70 RUSH CITY MN CHISAGO 0231 PM

10.40 WSW LONG LAKE MN HENNEPIN 0600 AM

10.40 CHANHASSEN MN CARVER 0600 AM

10.10 NEW HOPE MN HENNEPIN 0102 PM

10.00 3 N FOREST LAKE MN CHISAGO 0104 PM

10.00 SW BURNSVILLE MN DAKOTA 0216 PM

10.00 MANKATO MN BLUE EARTH 0951 AM

10.00 MONTGOMERY MN LE SUEUR 1130 AM

10.00 AMBOY MN BLUE EARTH 0930 AM

9.60 HUTCHINSON MN MCLEOD 0700 AM

9.50 NORTH BRANCH MN CHISAGO 0819 AM

9.50 VADNAIS HEIGHTS MN RAMSEY 0708 PM

9.50 NEW MARKET MN SCOTT 0258 PM

9.20 2 W PRIOR LAKE MN SCOTT 0600 AM

9.20 ST LOUIS PARK MN HENNEPIN 0703 PM

9.20 NORTH BRANCH MN CHISAGO 0703 PM

9.10 WACONIA MN CARVER 0700 AM

9.00 1 NE MINNESOTA LAKE MN BLUE EARTH 0953 PM

9.00 3 NNW MINNEAPOLIS MN HENNEPIN 1243 PM

9.00 CHISAGO CITY MN CHISAGO 0301 PM

8.60 1 W CARVER MN CARVER 0600 AM

8.60 MADELIA MN WATONWAN 1025 AM

8.50 1 SE CHASKA MN CARVER 0148 PM

8.50 EDINA MN HENNEPIN 0505 PM

8.40 1 SE HENDERSON MN LE SUEUR 0600 AM

8.30 5 SE ELK RIVER MN ANOKA 0148 PM

8.20 INVER GROVE HEIGHTS MN DAKOTA 0715 PM

8.00 MINNEAPOLIS MN HENNEPIN 1200 PM

MEASURED AT THE MINNEAPOLIS/ST PAUL

INTERNATIONAL AIRPORT.

8.00 SHAKOPEE MN SCOTT 0703 PM

7.70 3 NW AFTON MN WASHINGTON 0726 AM

7.70 4 NE WOODBURY MN WASHINGTON 0600 AM

7.30 3 SE LAKE ELMO MN WASHINGTON 0800 AM

7.20 ROCKFORD MN HENNEPIN 0700 AM

7.00 HAMBURG MN CARVER 0800 AM

6.70 LAKEVILLE MN DAKOTA 0703 PM

6.50 6 NW RICE LAKE WI BARRON 1024 AM

6.50 FARMINGTON MN DAKOTA 0700 AM

5.50 3 N QUAMBA MN KANABEC 0712 AM

5.00 1 E CUMBERLAND WI BARRON 0205 PM

5.00 CANNON FALLS MN GOODHUE 0700 AM

5.00 1 SSW RIVER FALLS WI PIERCE 0600 AM

4.80 ROBERTS WI ST. CROIX 0800 AM

4.00 BALDWIN WI ST. CROIX 0700 AM

4.00 ZUMBROTA MN GOODHUE 0700 AM

3.00 STILLWATER MN WASHINGTON 0712 AM

3.00 REDWOOD FALLS MN REDWOOD 0700 AM

3.00 2 SE CHETEK WI BARRON 0600 AM

3.00 7 S HILLMAN MN MORRISON 1111 PM

2.90 MILACA MN MILLE LACS 0700 AM

2.50 RED WING MN GOODHUE 0813 AM

2.50 OWATONNA MN STEELE 0700 AM

2.30 3 WNW LADYSMITH WI RUSK 0600 AM

2.10 SPRING VALLEY WI PIERCE 0800 AM

2.00 RICE MN BENTON 0700 AM

2.00 JIM FALLS WI CHIPPEWA 0600 AM

2.00 2 NNW SPRINGFIELD MN BROWN 0600 AM

1.10 ELK MOUND WI DUNN 0700 AM

1.10 N WILLMAR MN KANDIYOHI 0700 AM

0.90 ST CLOUD MN STEARNS 1201 AM

GOES visible satellite shows the snow cover this weekend.

The "anything goes" year of 2010 continues to amaze and deal us weather records.

I can't wait to see what's left in the next 6 weeks!

PH