While working as a forecaster at the Indianapolis NWS Office in the 1970s, the computer models were getting good enough to extend a forecast out about seven days. For the most part, they were fairly accurate through seventy-two hours. We applied a number of what was known as cook book rules in forecasting snow amounts. Many are still basic enough to use today.
One of the standard synoptic forecasting techniques was to expect the heaviest snow to accumulate about 150 miles north of the track of the center of lowest pressure. That was close to the case for last Saturday's snowfall of six inches from Clear Lake, Iowa to Cumberland, Wisconsin.
Looking out at the long range GFS, I can't find a system that has the potential to produce signifcant snow in the Upper Midwest between now and December 24th. But I'm experienced enough to doubt model output data after five days, particularly in the winter months. I know this much, daylight is continuing to grow short and we are gradually approaching the historically coldest days of the season.
Our friends at the State Climate Office have posted this graphic of the probability of a White Christmas in Minnesota. Here's a statement they included with the image; The best chances of having a white Christmas is almost guaranteed in the Boundary Waters Canoe Area and a good part of the Arrowhead. The chances decrease to the south and west and the best chance for a "brown" Christmas is in far southwest Minnesota where chances are a little better than 60%.
You can dive into more details of their research by clicking on their White Christmas post.
Cold air is still coming, but so is the moderation. Once we get through the next forty-eight hours of winter chill there will be a nice bump-up in temperatures for Saturday afternoon through Sunday.
The GFS has been consistent with readings in the lower to perhaps the middle 30s on Sunday. Here's a snapshot of expected surface temperatures and winds for noon on Sunday.
Before I turn the weather fun back to the Chief meteorologist, Paul Huttner, I'll leave you with this extended temperature outlook for the next 8 to 14 days from NOAA's Climate Prediction Center. I'll not include an editorial comment.
This is not a magnitude of warmth or cold but a confidence level of above or below normal temperatures. May the wind be always at your back.
3 degrees - low temp in parts of the metro Friday morning
March 2nd last time we were that cold at MSP Airport (-3 degrees)
15 forecast high temp at MSP Friday
28 forecast high Saturday
38+ forecast highs by Sunday afternoon!
40s possible Sunday in snow free areas west of the metro
Brief Wintery Blast:
Grab the big coat Friday.
The coldest air in 9 months has invaded Minnesota. Temps should hover a few degrees either side of 0 in much of Minnesota early Friday morning, with some solid sub-zero readings up north. Even with bright sun Friday, temps will not recover out of the teens.
A milder Pacific breeze will begin to moderate temps slightly Saturday. Bank thermometers should manage to flash 28 by 3pm Saturday. By Sunday a milder Pacific air mass will work on melting some snow in southern Minnesota. Highs should top out in the upper 30s to near 40 in the metro, with some 40s possible in snow free areas west of the metro.
Sharp snow cutoff visible from space
Speaking of snow free areas, check out Thursday's MODIS Terra's 250 meter resolution visible image. You can clearly see several interesting features. Snow cover is evident along the Minnesota River into the Twin Cities. A sharp cutoff on the western edge of the snowpack runs just west of the metro, with bare ground out west in Hutchinson and Willmar.
You can see why forecasting snowstorms is one of the most difficult forecast meteorologists have to make. You can literally drive from 3" of snow to bare ground in about 5 minutes!
Possible "Panhandle Hook" next week?
I'm keeping an eye on a potential system for next Wednesday & Thursday. The GFS is spinning up a strong upper low in the Texas-Oklahoma Panhandle region early Wednesday.
The system should gulp down moisture from a wide open Gulf of Mexico and pump it north into Minnesota Wednesday.
They system appears warm enough for rain to start, but rain could change to snow as the low moves by Thursday.
It's way too early to tell how this might pan out, but there is a decent chance of rain and or snow next Wednesday & Thursday.
Artcic Report Card: Warmer
NOAA has an interesting video on changes in the Arctic as a result of persistent warming in recent decades.
2011: Year of Extreme Weather
NOAA also has a nice compilation of extreme "billion dollar" weather events in 2011.
"From extreme drought, heat waves and floods to unprecedented tornado outbreaks, hurricanes, wildfires and winter storms, a record 12 weather and climate disasters in 2011 each caused $1 billion or more in damages -- and most regrettably, loss of human lives and property."
Good to be back home:
I'm back form a week in Vegas visitng my best friend from college. It was a great week, but it's good to be back home!
There are some interesting things going on around Vegas in weather & water news. More on that tomorrow.