Tracking narrow (heavy?) snow band for Tuesday night

We’re still 24 to 36 hours away from what looks like the season’s first significant winter storm near the Twin Cities. Still, there are several questions as to the precise track and temperature profile of the system and to how much snow will fall.

The heaviest snow band with this system looks narrow, maybe 50 miles wide. That means any small shift in track could literally be the difference between flurries and shovel-able snow. Some snow looks likely for the metro, but I’m not ready to sign off yet on which parts of the metro will see (potentially heavy) snow or a light coating of slush and flurries.

The Twin Cities National Weather Service has pasted the winter storm watch right over the Twin Cites for Tuesday night.

(Image: National Weather Service)

It looks like precip may start as rain Tuesday, then change to sleet and snow by Tuesday night.

This system looks ‘temperature critical,’ meaning temps will be right around the 32 degree mark in the lowest mile of the atmosphere late Tuesday. With temps above freezing and warm ground, the first inch or two that falls will likely melt on contact. It may take until after dark Tuesday evening when temps fall to near 32 degrees for snow to really stick and begin accumulating.

Here’s a look at the change from rain to sleet to snow Tuesday from the European Centre for Medium-Range Weather Forecasts.

(Image: Euro model via Weatherspark)

Here’s a map of the snowfall probability by Wednesday from the National Oceanic and Atmospheric Administration. As you can see the agency paints a high chance –60 percent-plus of at least 2 inches of snow for the metro.

Image: NOAA

Chances for 4 inches or more drop to around 40 percent for the Twin Cities, but remain a 50/50 shot southwest toward Sioux Falls, S.D., Redwood Falls and Mankato.

(Image: NOAA)

Bottom line: It’s still early to pinpoint snowfall totals, but it’s looking more likely that we may get a shovel-able snow in parts of the Twin Cities Tuesday night. Questions surrounding temperature profile and precise storm track still preclude high confidence in snowfall totals.

I’ll be watching today’s model runs for any changes in storms track and temperature profile.

Action: You should plan for the possibility of a rain to sleet to snow event in the Twin Cities by Tuesday night. Tuesday PM rush hour looks wet with rain changing to sleet and snow in the metro. Eventual totals still to be determined.

Here’s the extended language from the Twin Cities NWS on the winter storm watch.

URGENT – WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
308 AM CST MON NOV 4 2013

…SNOWFALL LIKELY TUESDAY AFTERNOON AND TUESDAY NIGHT…

A LOW PRESSURE SYSTEM WILL TRACK NORTHEAST ALONG A TIGHT TEMPERATURE GRADIENT FROM THE SOUTHERN PLAINS INTO WISCONSIN BY TUESDAY NIGHT. WIDESPREAD MODERATE TO HEAVY PRECIPITATION WILL DEVELOP ALONG THIS BOUNDARY LATE TUESDAY…AIDED BY MOISTURE FROM TROPICAL STORM SONIA IN THE EASTERN PACIFIC.

TEMPERATURES WILL COOL TUESDAY AFTERNOON AND ALLOW RAIN TO TRANSITION TO SNOW. IT IS POSSIBLE MANY AREAS ACROSS SOUTHERN AND EASTERN MINNESOTA AND WESTERN WISCONSIN COULD SEE 4 TO 6 INCHES OF SNOW…WITH LOCALLY HIGHER AMOUNTS OF 7 INCHES BY EARLY WEDNESDAY MORNING. THESE AMOUNTS ARE SUBJECT TO CHANGE BASED ON THE TRACK OF THE SYSTEM AND HOW TEMPERATURES FALL TUESDAY AFTERNOON AND EVENING. A WINTER STORM WATCH HAS BEEN ISSUED EAST OF A LINE FROM REDWOOD FALLS TO CLEARWATER AND MORA… EXCEPT FOR EAU CLAIRE…PEPIN…AND FREEBORN COUNTIES.

308 AM CST MON NOV 4 2013

…WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY AFTERNOON
THROUGH LATE TUESDAY NIGHT…

A WINTER STORM WATCH REMAINS IN EFFECT FROM TUESDAY AFTERNOON
THROUGH LATE TUESDAY NIGHT.

* SNOW ACCUMULATION: 4 TO 6 INCHES…WITH HIGHER AMOUNTS POSSIBLE.

* TIMING: RAIN WILL OVERSPREAD THE AREA FROM THE SOUTH EARLY TUESDAY AFTERNOON WITH A TRANSITION TO SNOW OCCURRING TUESDAY AFTERNOON AND EVENING. THE SNOW WILL TAPER OFF LATE TUESDAY NIGHT OR EARLY WEDNESDAY MORNING.

* IMPACTS: THE FIRST HEAVY SNOW OF THE SEASON IS POSSIBLE DURING THE TUESDAY AFTERNOON COMMUTE. IN ADDITION…IT IS LIKELY TO BE A WET SNOW AND ANY TREES WITH LEAVES LEFT ON THEM MAY BE STRESSED…LEADING TO BROKEN TREE LIMBS AND ISOLATED POWER OUTAGES.