Posted at 3:21 PM on December 17, 2012
by Craig Edwards
Let's take this weather story one day at a time.
Light snow should form in southwest Minnesota overnight and steadily move east during the day tomorrow. Earlier, I thought tomorrow's morning rush in the Twin Cities would be a challenge, now it looks like any light snow should hold off until later in the morning.
Things stay pretty quiet for much of northwest Minnesota on Wednesday, but it will be a different story in southeast Minnesota and much of Wisconsin come Wednesday night.
Computer models are considered guidance products and a tool of the trade. A meteorologist refines the forecast track by examining the jet stream, vertical moisture and temperature profiles, surface weather reports and satellite imagery. Once the moisture shows up the Doppler radar becomes a key tool.
Here's the latest thinking from NOAA's precipitation forecast group on the probabilities of snowfall accumulations of four inches or greater from the Wednesday night/Thursday storm.
Looking at the moisture available and the precipitation that will be generated by strong dynamics, there is the possibility for more than a foot of snow, most likely from about Tomah to Wausau, Wis.
A Winter Storm Watch means that hazardous winter weather, in this case near blizzard conditions, will be possible on Wednesday night and Thursday.
The National Weather Service in La Crosse posted the following about the storm's potential:
A STRONG WINTER STORM WILL MOVE INTO THE REGION ON WEDNESDAY
NIGHT...BRINGING THE POTENTIAL FOR HEAVY SNOW AND STRONG WINDS
THROUGH THURSDAY. CONFIDENCE IS GROWING THAT A 6 TO 12 INCH BAND
OF SNOW WILL OCCUR WITH THIS STORM. THE MOST LIKELY TRACK OF THE
STORM AT THIS TIME WOULD PLACE THE HEAVIEST SNOW ACROSS PARTS OF
NORTHEAST IOWA...SOUTHWEST AND INTO CENTRAL WISCONSIN. GUSTY WINDS
WILL INCREASE AND BLOWING AND DRIFTING SNOW WILL ALSO BECOME A
While there will be several more computer runs before the storm really gets cranking, the models continue to place the Twin Cities on the northern edge of accumulating snow.
The forecast from the NAM suggests the storm will be roaring midday on Thursday, with very difficult travel from the Twin Cities toward Dubuque and Madison. Please keep abreast of travel conditions beginning late Wednesday.
Definition of a Blizzard Warning (from NWS) - Sustained wind or frequent gusts greater than or equal to 35 mph accompanied by falling and/or blowing snow, frequently reducing visibility to less than 1/4 mile for three hours or more. This is the most dangerous of the winter storm types.
No warnings are valid at this time. Stay tuned for developing hazardous winter weather.
Am I right that the official definition of "blizzard" used to include air temperatures below 20 degrees F?
Mark, at one time, I believe the Blizzard criteria did include a temperature. That was wisely dropped. During the hard winters of the 70s and 80s, there used to be headlines for Ground Blizzards based on cold winds creating blinding snow that had previously fallen.
To be on the safe side, we sometimes would say near Blizzard conditions to heighten the awareness of difficult travel, if winds were just shy of Blizzard criteria.