Friday, December 13, 2013 4:20 AM
Prepared by Bob Weisman
Professor of Earth and Atmospheric Sciences
Saint Cloud State University
Earth and Atmospheric Sciences Department
Saint Cloud and Vicinity Forecast
"California Dreamin' on Such a Winter's Day?"
...Or Is It "Hot! Hot! Hot!?"
It's actually milder than average right now. Temperatures reached 16 degrees for a high yesterday (see NWS: Last 72 hours of St. Cloud Observations), the warmest temperature St. Cloud has seen since our snowstorm on the 4th. But that high is still 9 degrees colder than the mid-December average high of 25 degrees. The "heat" actually intensified overnight as clouds rolled in from the next weak storm system. So far, temperatures haven't dropped below 10 degrees overnight (see UCAR
Minnesota surface chart loop). However, this is working out a lot like "California Dreamin:'"during our cold season, we tend to be sunniest when it's really cold, since that arctic air can't hold much moisture. That also cools us, because our nights are so long, so the time spent losing radiation to space is longer than the time gaining energy from the sun. When we have clouds, they absorb a lot of the outgoing radiation from the earth and return a good chunk of this. They also block a good chunk of the sun's radiation, but again the long nights mean that the insulation effect is bigger. So, when we are more mild, "all the leaves are brown and the sky is gray."
One Weak Storm System Leaving, Another One Coming
The clouds have also been producing a line of snow flurries just to the north of St. Cloud from North Dakota through central Minnesota (see NWS
Upper Mississippi Valley radar loop). There has been snow in places like Brainerd, Little Falls, and Sauk Centre, but the visibilities are 7 to 10 miles in the snow, meaning that they are only seeing a few stray snowflakes. We will see these on and off flurries for a while this morning, but they will become far less frequent this afternoon as one weak ripple along this front through Minnesota (see NWS
HPC Latest North American zoom-in surface map) moves off to east. The northeast winds that have started in the early morning hours will continue, allowing some of the colder air from the north to push in, but that only means that temperatures will hold between 5 and 15 for most of the day. There will be a little blowing snow with the northeast winds at 8-15 MPH and a bit of a bite to the air, but any wind chills will be in the minus single digits at worst (see NWS
wind chill chart).
That front parked over Minnesota is quite dramatic: note the 40-degree temperature difference between southwestern Ontario (temperatures in the minus 20s) and southern Iowa and the Omaha area (temperatures in the plus 20s on the UCAR
Minnesota surface chart loop and the NWS
HPC Latest North American zoom-in surface map). We will mostly be close to the front for the next several days, so any low that scoots along it will take advantage of that temperature contrast to squeeze out some light snow. There won't be any deeper moisture, so any snow amounts will range from flurries, as in this morning's weak storm, to as much as a couple of inches.
The next system is on the heels of the first and is now pushing through Montana on the NWS
HPC Latest North American zoom-in surface map. That's the cause of most of the deeper clouds (see infrared loop on College
of DuPage Satellite and Radar Menu) straddling the Canadian border from Montana and Alberta to North Dakota and Manitoba. There's only the narrow string of radar echoes in the US right now (see NWS
Upper Mississippi Valley radar loop), but there's more extensive snowfall in Manitoba back into Alberta (see Environment
Canada Prairie Provinces radar loop and UCAR
Canadian Prairies surface chart loop). That system will push through this evening into tomorrow morning, so we could end up with a coating of snow, but I still think accumulations will be generally under an inch.
Cooler Saturday, Milder Sunday (With Some Snow)
The colder air will win out for tomorrow, but it will be a glancing blow, not the direct hits we've seen so much in the past week. Look for high temperatures to hang around 10 degrees Saturday with possibly a low below zero early Saturday evening.
However, the roller coaster of temperatures will trend upward again by late Saturday night with readings climbing into the plus single digits in the early morning hours and continuing to rise into the teens on Sunday. Again, this "mild-up" will come with clouds from the next Pacific storm system. The computer forecasts agree that this Sunday system will be stronger, so it will have a chance to drop that 1-2 inches of snow. They don't agree about the timing of the storm, with the fastest one trying to start the snow early Sunday morning and the slowest one holding off until Sunday afternoon or evening.
A Shot At 20's Early Next Week??
Even milder air is forecast for Monday with some forecasts showing temperatures near or above freezing at 5,000 feet above the ground. However, that warm air aloft will trap the leftover cold air near the ground, so I don't expect to see temperatures that warm. We will have a shot, however, at near normal readings with temperatures in the 20's on Monday.
As I've noted all week, this type of weather pattern with a strong front in the area and a series of storms moving along it is harder to forecast. So, my confidence in the forecast is less than usual and really drops off after Monday. I'll hazard a guess that the highs in the lower 20's will continue into Tuesday. On Wednesday, the European computer forecast, which has been doing better than its US counterparts, is calling for a major warm-up. In areas with less snow cover, that could lead to temperatures in the 40's. If it works out perfectly, some parts of central Minnesota could make a run at freezing, which would really be "Hot! Hot! Hot!" However, these forecasts have dramatically changed from day-to-day in this pattern, so I'm not ready to go nuts for a warm-up yet.
The next day that looks forecastable is next Friday as it appears the cold air may surge southward again, but how it gets here (with or without a storm) and how quickly it arrives between Wednesday and Friday is still a huge question mark. I must also note that, in this pattern, we have seen some huge changes in 5-7 day forecasts. Last weekend, Sunday looked mild, then by early this week, it looked like another arctic blast could hit, and now I'm looking for a brief cooldown on Saturday with a warm-up on Sunday. The change for next Friday is the result of a major steering wind change to break the current pattern, but it's still way too early to be sure.
This Weekend's Major Storm Will Hit...
While we deal with the weak storms running along the nearby front, a stronger storm is starting to get going across the Southern Plains. Clouds have gathered across Texas overnight (see infrared loop on College
of DuPage Satellite and Radar Menu). There's no strong low at the ground yet, but one will develop as the powerful mid-atmosphere storm over the Southern Rockies (see counterclockwise circulation on the water vapor loop from College
of DuPage Satellite and Radar Menu) pushes over the Plains and heads northeastward over the weekend (see NWS HPC Short-Range forecast map). This system will be warmer than last week's, so there will be a fair amount of rain in the Interior South, moving to the Southeast and Carolinas. On the north side of this storm, there is the possibility of 4-6 inches of snow today from St. Louis through central Illinois and into Indianapolis and 6-12 inches of snow from New York and Pennsylvania into New England tomorrow. While the ice threat isn't as high as in last week's storm, parts of southern Missouri and northern Arkansas could see a coating of sleet and freezing rain at the end of their precipitation today and tonight. Tomorrow, ice could spread from the central Appalachians and could get close to Washington, Philadelphia, and New York City. Right now, the winter storm watch covers the area to the northwest of the major cities, but it will have to be watched. Significant ice also means the same kind of troubles seen in Arkansas and northeast Texas with downed trees and power lines possible.
Meanwhile, the snowfall in the lee of the Great Lakes continues to be crazy with some three day totals over 3 feet of snow in north central and southwestern New York and a foot and a half in the Keewinaw Peninsula and eastern Upper Michigan. Redfield along the south shore of Lake Ontario still is the leader with that insane 44 inch total.
The highest the temperature got during the daylight hours was -3 degrees, although clouds moving in last evening (see infrared loop on College
of DuPage Satellite and Radar Menu) helped to push readings back towards zero during the late evening. However, St. Cloud never got higher than -1°F. On the average, St. Cloud has 4 days for entire winter, but in the past 15 winters, only 2004-2005 and 2008-2009 have had the average number of days below zero.
Temperatures have yet to top zero early this morning as the clouds have moved on (see infrared loop on College
of DuPage Satellite and Radar Menu). Temperatures are still in the minus single digits, so today marks the 8th straight day with a low below zero. However, it feels a lot warmer since the light winds, where they are blowing, are only producing producing wind chill in the minus 10 to minus 15 range (see NWS
Minnesota Hourly Weather Round-Up). We've also picked up a light coating of snow. These light snow amounts are also consistent with January-type weather, since the air can't hold very much moisture when it is so cold. Including early this morning, 6 of the first 12 days of December have had measurable snow, but there's only been as much as an inch on 2 of the 6 days.
In the meantime, the lake effect snow machine is slowly beginning to ease off as you can see more of the dark area (meaning warmer temperatures) through the entire lakes on the (see infrared loop on College
of DuPage Satellite and Radar Menu). Lake effect snow warnings are still in effect along the southeast shores of Lakes Erie and Ontario. As of last night, some places along the lakes in southwestern and western New York have picked up 2 to nearly 4 feet of snow (44 inches in Redfield). Those totals will be used to update this map after 7 AM (push the 72-hour snowfall button to see totals from the last 3 days).
Milder conditions should occasionally allow temperatures to climb above 15 degrees, a temperature that would make salt more effective at melting ice, but I don't expect a lot of sunshine at those times, so you'll still have to be careful about icy spots. The moderation should be enough to keep more black ice from forming or allowing wind chills to show any threat of frostbie (at least through Monday....still don't know how cold the next forecast arctic outbreak will be on Tuesday and Wednesday...or if it happens).
Note the contents of the cold weather survival kit from NWS Sioux Falls (scroll to bottom).
Cold Facts About Cold
As if you didn't know, the first 11 days of December have produced an average temperature of 6.6°F in St. Cloud. That is more than 12 degrees colder than the December average. If that level of cold lasted all month, this December would rank 8th among St. Cloud's 10 coldest Decembers. It still would have to be much colder to approach December 2000 with an average of 3.8°F. In that December, there were three days with a high colder than zero and 20 days with a low below zero, including two mornings with lows in the minus 20's. And, this average, while still well below normal, will be climbing the next few days.
Yesterday, the temperature climbed above zero early, so we still have three full days below zero (4 days on average for entire winter). We should snap our streak of 8 straight days with a low below zero, as we've above 10 all night and I don't anticipate getting below zero before midnight tonight. In fact, of the next several days, I only see a chance of a sub-zero low on Saturday night. (average number of sub-zero lows: 43 days all winter) Our coldest low temperature was -17, so we still haven't had a low of at least -20 (average: 5 days per cold season; none since Feb. 10, 2011).
See Forecast Below
Friday 12/13: Cloudy, breezy, and a little colder with occasional morning flurries Temperatures holding between 5 and 12 all day. Winds: NE 8-15 MPH. Wind chill(seriously?): in the minus single digits. Chance of measurable snowfall: 30% in the morning, 20% in the afternoon
Friday Night: Cloudy with occasional light snow or flurries and a shade colder. Between a dusting and an inch of new snow could accumulate between Friday night and Saturday morning. Low: between +2 and +6. Winds: E 5-15 MPH. Wind chills: between -15 and -5 (this is nothing). Chance of measurable snowfall: 50%.
Saturday 12/14: Cloudy with a chance of morning light snow, tapering to flurries in the afternoon. High: between 10 and 15. Winds: NE 5-10 MPH, shifiting to W late. Chance of measurable snowfall: 40%
End of "Reasonable" Forecast Certainty
Saturday Night: Clear evening, some clouds late and a little colder. Low: between -5 and 0, rising to near zero by morning. Winds: NW 5-10 MPH. Wind chills: in the minus teens (yawn). Chance of measurable snowfall: 10%.
Sunday 12/15: Thickening clouds with a chance of more light snow or flurries. Highs: between 8 and 12. Winds: light NW. Chance of measurable snowfall: 20%
For Entertainment Purposes Only.
Sunday Night: Cloudy with a better chance of accumlating light snow or flurries. Between a dusting and an inch is possible by morning. Temperatures steady or slowly rising into the teens. Winds: light W. Chance of measurable snowfall: 40%.
Monday 12/16: Mostly cloudy with perhaps a flurry and actually December-like (???!!!) High: between 22 and 26. Chance of measurable snowfall: 20%
"Do I Feel Lucky? Well, Do Ya Punk?"
Tuesday 12/17: Continued seasonably mild. Maybe even a bit of sun(??!!). High: between 22 and 26. Low: in the teens. Chance of measurable snowfall: 20%
Wednesday 12/18: Continued seasonably mild. High: between 22 and 26. Low: in the teens.
Thursday 12/19: ??????
Friday 12/20: Turning a bit colder???.
Forecast Confidence (10 - "Know what gas will
cost next week, Bob?"; 0 - "Been a victim of road rage lately, Bob?"): 7 Friday, 6 Friday night and Saturday, 5 Saturday night, 4 Sunday, 3 Sunday night and Monday, 1 Tuesday, 0 Wednesday and Thursday, 1 Friday.
Yesterday's High: 16°F; Overnight Low (through 5 AM): 12°F
St. Cloud 24-Hour Precipitation (Through 4 AM): None; SCSU Precipitation (Through 4 AM): TBA
Normal Temperatures for December 13 - High: 25°F;
Next Update: Monday, December 16 8:00 AM
Let me know what you think about this forecast and discussion by emailing SCSU
meteorology professor Bob Weisman. Please note that I make the forecast, not the weather!
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go to the Earth and Atmospheric Sciences Department home page.