It has only been 18 hours since I released my initial forecast for today's snowfall. A lot has changed since then and can best be summed up by Ron Burgundy.
As of noon today the ECMWF and the HRRR are in good agreement setting up a band of very heavy snow along I-35 in Minnesota extending into northwest Wisconsin.
This is turning out to be a classic panhandle hooker and is only picking up more gulf moisture as it heads northward. The slower progression of the storm today will allow the gulf moisture to combine with arctic air and produce heavy snow this evening. The timeline of what to expect is below.
Storm total accumulations will range from 8-10" across the far west metro to 12-16" across the eastern metro, with some locally higher amounts possible. Storm total forecast for MSP: 12-14"
- Light rain is currently changing to sleet and snow across the metro. All snow is expected between 1-2 pm.
- The heaviest snow is expected to fall between 3pm and midnight tonight. Heavy accumulations in the order of 1-2" per hour are likely, especially between 3pm-8pm. Thundersnow is also possible within this time frame.
- The snow will end across the area during the overnight hours, but very strong winds will produce blowing and drifting snow through tomorrow.
I know many have been waiting for the Twin Cities to receive its first big snowfall of the winter so far. It's here. Settle in with a big bowl of popcorn and the drink of your choice and enjoy the show.
It has been awhile since Minnesota has seen a significant snowfall from anything other than a clipper. Southwest flow arrived just long enough to give us a tiny taste of spring, followed by a very potent storm that will produce heavy snow across Minnesota and Wisconsin, and severe weather to the south for Thursday. To the left is my total snowfall forecast for Thursday.
The biggest challenge this system will have when it comes to producing snow is overcoming warm air. With a slow arriving arctic airmass to the north, temperatures will remain near or above freezing at the surface. This could lead to a rain/snow mix at first and reduced snowfall ratios on the order of 8:1 or 10:1. A timeline of what to expect is listed below.
Storm total forecast for MSP: 6"
- A rain/snow mix will develop across the Twin Cities for the morning rush hour. Temperatures will be near or above freezing, meaning snow may have difficulty accumulating at first.
- Precipitation turns to all snow by the late morning and becomes very heavy by the early afternoon, with snow ending during the evening. Accumulations will range from 3" across the far west metro, to close to 9" near the Wisconsin border. I think accumulations of 4-7" are most likely inside the I-494/694 metro loop. Very strong winds will create blizzard conditions across rural areas with blizzard warnings already out for southern Minnesota and northern Iowa.
- Unfortunately northwest flow returns behind this system, in which it feels like we have been stuck in since last winter. This means the return of arctic air, with subzero lows likely through all of next week. By late next week MSP could be looking at lows well into the teens below zero. The good news is we are used to the cold by now, and it is almost March. Even though the weather pattern looks bleak, spring is not too far around the corner.
Hopefully everyone is staying warm through our early December arctic outbreak. It's been awhile since it has been this cold, this early! Tomorrow won't be quite as bad with temperatures at least rising into the lower teens. Along with the warmer air comes more moisture and a chance of snow ahead of our next arctic cold front. To the left is my forecasted snow totals for the day tomorrow.
- Snow will spread across the area late tonight into early tomorrow morning. This will be a very slow duration event, with very light fluffy snow falling throughout the entire day. Right now it looks like the heaviest snow can be expected between noon - 6pm.
Storm total forecast for MSP: 3"
- 2-4" is expected for most of the Twin Cities, with 3-6" possible from Burnsville-Eagan-Woodbury and points southward. Locally higher amounts are possible as you head further south from Mankato to Rochester.
- Arctic air will remain in place through the week, with below 0 lows continuing. Several quick but weak clippers are possible throughout the week, bringing us periods of off and on light snow.
- If you're looking for warmer temperatures, we could finally see them by next Friday. There are still uncertainties on whether this warmer air will hang around, or quickly get replaced by more arctic air from Canada.
Our first major snow storm of the 2013-2014 winter season is strengthening to our west. Below is what you can expect over the next 24-36 hours.
- Snow is currently developing over the Dakotas and will continue to fill in throughout the overnight as it slowly moves to the east.
- Drizzle and freezing drizzle will develop over southern and southeastern Minnesota including the Twin Cities overnight as warmer air moves in aloft. With temperatures near or below freezing at the surface, ice accumulations are possible overnight.
- Light snow is possible overnight in the Twin Cities, but the heaviest accumulations will occur while everyone is at work tomorrow, between 9am-5pm. Warmer air aloft over the southeast metro will limit totals and produce a very sharp gradient across the metro. 1-3" is expected for the southeast metro while the northwest metro could receive 6-9" with a much longer period of snow.
Storm total forecast for MSP: 5"
- The heaviest snows will fall across the north shore where lake enhanced snow bands could produce another 1-1.5 feet of snow.
- Strong winds will also cause blowing and drifting snow across the Dakotas and western Minnesota. Brutally cold air will move in behind this system Thursday through much of next week with lows dropping well below 0.
- Snow will become possible again on Sunday as another strong system approaches from our southwest.
It's better late than never, but I finally had time to sit down and take a look at what to expect for the next long 3-4 months of winter. Long range forecasts are never easy but there are several indicators that can be used to come up with a good scientific guess on how this winter may play out. You can start by taking a look at my 2012-2013 Winter Forecast
. I won't go into quite as much detail in this forecast, but will still touch on the same components. After a warm December, last year's forecast actually played out closely to how I thought it would. On April 1st, 2013, Minneapolis-St.Paul had received 49.3" of snowfall, only .3" off of my season forecast for 49". If you're that close on April 1st, most years that ends up being an excellent forecast. Unfortunately I didn't foresee winter lasting into May. Add another 18.4" on top of that bringing our season total to 67.7", didn't make the forecast look quite as good. What do I expect for this year? More snow and more cold, and winter will really begin to set in next week.
ENSO - Neutral Pattern to Continue?
The most helpful tool in making long range winter forecasts is taking a look at the El Nino - Southern Oscillation (ENSO). Very strong correlations to weather patterns can be made when an El Nino or La Nina is present. By taking a look at the graphic to the right, we can see that ENSO neutral to weak La Nina conditions are currently present. Unfortunately ENSO neutral conditions can make weather patterns much more erratic and difficult to predict. Much like last year neutral conditions are expected to continue through the winter, with a chance of a weak La Nina developing.
The Arctic Oscillation (AO) and North Atlantic Oscillation (NAO) are two key indices to monitor during the winter. When the AO is negative, this brings very cold air to the Midwestern U.S., whereas a positive AO brings the opposite conditions. The NAO is similar, however, the temperature correlations are not quite as strong. A negative NAO typically brings increased precipitation to the central U.S.
So far this fall the AO has been positive since the middle of October. This is a little different from last year where the AO and NAO were largely negative through the fall.
Research has shown strong correlations between an above average Siberian snow pack in October producing a negative AO throughout the winter. Once again Siberian snow pack was near to slightly above average in October 2013. This leads me to believe the AO will move into a more neutral to negative phase, especially as we head into January and February. The NAO has remained more neutral over the past few weeks, and I also expect this to remain in the neutral to negative phase throughout the winter.
After taking a look at some of the basics above, and how our weather has behaved over the past year, I picked out four winters I thought could most resemble our upcoming winter, December-April. They are 1960-61, 1978-79, 1996-97 (I've mentioned in several other posts how I think 2013 has been very similar to 1996) and 2008-09. None of these winters are good news if you are looking for a warm winter. The northern plains experienced well below average temperatures in all of these winters.
I know April is actually a spring month, but April 2013 definitely felt more like winter than spring. It is common for our snow pack to last into April which is why I included it in this year's forecast.
Taking a look at precipitation anomalies over the same winters shows near to above average snowfall across the northern U.S. and a very wet southeastern U.S. The west coast, especially in the northwest, experienced drier than average conditions.
2013-2014 Winter Prediction
Finally, here's a look at what I expect temperature departures from average to look like across the U.S this winter. The northern/central plains will feel the effects of a negative AO with below average temperatures likely December - April.
If you're looking for a vacation spot this winter, Florida might not be a bad place to go. This is the only state I am forecasting above average temperatures.
Unlike last year where northwest flow completely dominated the weather pattern throughout the winter, southwest flow will develop over the next two weeks. I think this will occur more often throughout this winter compared to last year. This will help produce above average snowfall in the Rocky Mountains as well as into the central/northern plains and the Midwest. This will also produce very wet conditions in the southeast as well as slightly drier conditions for the northwest coast.
Northern Plains and the Twin Cities
Overall, I expect above average snowfall for the southern portion of the northern plains including the Twin Cities. A significant trough looks to set up across the western portion of the U.S. through the first half of December. This pattern is conducive for heavy snow across the central and northern plains bringing us several chances for snow throughout the month. I think December will be the snowiest month followed by a very cold January and February.
Total snowfall prediction for the Minneapolis-St. Paul International airport: 71"
71" may seem like a lot, but it is only 3" more than last year. Our snow pack may be slow to melt late March into early April, but unlike last year I don't think we'll see any late April or early May snow storms. After what looks to be a rough winter, maybe mother nature will finally deliver us a more normal spring.
It seems like I make a promise before every summer to keep up with the blog more than I did the previous year. Well, I failed once again as it has been three months since my last post. Summers are way too short in Minnesota to begin with, so I end up playing softball two nights a week, golf on the weekends, and just enjoy being outdoors and not in front of a computer. On top of all of that, I still try to storm chase as much as possible...well except for this year. Everyone thought that 2012 was a rough year for storm chasing, but 2013 has been even worse across the northern plains. Other than a very active two weeks in Kansas and Oklahoma at the end of May, it has been another quiet year for tornadoes around the U.S. I enjoy blogging about unusual weather, thunderstorms, snow, cold, you name it. My last post at the end of April was about accumulating snow. It has been less than three months since our last accumulating snow. I can safely say that snow is still at least two months away, but we still can't get rid of the unusual cold weather across the U.S, especially for us in Minnesota. Click here to read the Twin Cities WFO write up about the record breaking cold from this weekend. Lows across northern Minnesota once again dipped into the mid to upper 30s this morning, where a frost advisory was in effect. Crazy for late July!So what does this mean for the rest of summer? I'll take a look at what I expect for August below.
The image to the left shows the temperature anomalies from January - June 2013. You can see that much of the central U.S. is running below normal this year, especially the Upper Midwest.
As I've mentioned in previous forecasts, this year compares very well with 1996. Over the same time period in 1996 you can see how much of the central/eastern U.S was below normal, especially the Upper Midwest.
Here's a look at how August 1996 turned out. Below average conditions continued for much of the central and southern U.S. The western U.S. remained above average - very similar to what has occurred across the western U.S. through the first half of this year.
Of course, just because a similar weather pattern occurred 17 years ago, doesn't necessarily mean this year will be exactly the same. No correlating years are ever perfect, and the weather will never behave exactly as it has in the past. But the best way to create more accurate long range forecasts, is to base them off of what has happened before in similar years.
Taking a look at the last 9 runs of the climate model - CFSv2 you can see the forecasted temperature anomalies for the month of August. Once again this paints much of the U.S, especially the central and eastern portion with temperatures well below average. This also compares favorably with the image above.
ENSO remains neutral to a weak La Nina, and has changed very little over the last year. This cycle in combination with slightly negative to netural AO/NAO has little effect on summer temperatures.
The ECMWF and GFS can give us a good idea of what will happen for the next 10-14 days, which now extends into the first half of August. These models continue to show a similar solution, with well below average temperatures continuing for the first half of the month, especially for the Great Lakes and Upper Midwest.
The best shot for the Twin Cities to even see 80º comes on Wednesday and Thursday this week, with Thursday being the more likely day. If MSP does not hit 80º on either of those days, it may be at least another week or longer before we see 80º again. Not what most Minnesotans expect as we head into August. I think the worst of the summer heat is over, and it may be tough to even hit 90º again by the end of the year. Don't worry though, summer is not completely over. There is still plenty of 80º days to be had with some humidity by the end of August and into September. The Minnesota State Fair almost always guarantees this. I like the heat and humidity to last as long as possible during the summer, but I'll never complain about an early taste of fall to relieve the AC bills, and make outdoor activities much more pleasant.
Rain is currently changing over to all snow in the Twin Cities. The combination of daylight, warmer ground, and temperatures above freezing, means it will be difficult for snow to accumulate until we move closer to sunset. I expect the heaviest accumulations to occur between 8pm - 1am. Snow will end during the early morning hours, giving plows time to clear the roadways before the morning rush hour.
I have increased my snow totals slightly as a very narrow band of 3-6" is expected across the metro. The heaviest snow is still expected to fall across northern Wisconsin, where a longer duration of snow will fall during the overnight hours.
I know this snow is getting depressing, but as I promised last night, this is the last accumulating snowfall for the season. Here is the 10 day forecast for MSP to lift your spirits.
Tuesday 40º/27º Partly Cloudy
Wednesday 43º/21º Rain/Snow Showers
Thursday 46º/32º Mostly Sunny
Friday 62º/40º Mostly Sunny
Saturday 68º/42º Partly Cloudy
Sunday 73º/51º Partly Cloudy
Monday 76º/56º Partly Cloudy
Tuesday 72º/56º Scattered T-Storms
Wednesday 67º/46º Scattered T-Storms
I really hope this is the last snow forecast I post on this site until late next fall. If it's not, I may lose it like everyone else. However, I'm very confident that tomorrow will be our last accumulating snowfall for the season.
Snow will develop and move eastward across South Dakota overnight tonight. After seeing plenty of rain tonight, the Twin Cities should remain mostly dry through tomorrow afternoon. A rain/snow mix will move into the Twin Cities between 5-7pm tomorrow evening, just in time for the evening rush hour. The good news is that snow will not be able to accumulate quickly enough to really slow down the evening rush hour. Any rain will quickly change to snow and continue into the overnight hours. All snow should end by the time most people wake up Tuesday morning.
I expect a narrow band of 2-4", roughly from Mitchell, SD through the Twin cities. Northern Wisconsin has the potential to see heavier snowfall, upwards of 4-8". As I mentioned earlier this should be our last accumulating snow for the season. There will be enough instability in the atmosphere to produce more rain/snow showers on Wednesday, but these will remain light.
60s and 70s Right Around the Corner
We are heading into the last week of April and highs in the 60s are now considered average. MSP has not reached 60 yet this spring. Most years we usually see 60s, 70s, and even an 80 or two by the end of April. Even with more snow on the way, I have good news when it comes to warmer temperatures. Our first 60 of the spring is only 5 days away. We will quickly melt the remainder of our snow throughout this week. The combination of no snow and that our sun angle is now as high as it is typically in August, will mean temperatures can rapidly warm. My forecast for the next week at MSP is below.
Monday 42º/32º Rain/Snow
Tuesday 40º/29º Partly Cloudy
Wednesday 45º/22º Rain/Snow Showers
Thursday 48º/32º Mostly Sunny
Friday 62º/40º Mostly Sunny
Saturday 67º/41º Partly Cloudy
Sunday 71º/51º Partly CloudyNow that there is light at the end of the tunnel, tomorrow's snow doesn't look so bad does it? It's been a long winter, but we only have a few more days to go. The next thing to watch will be how quickly severe
weather returns to the area. I expect a very active May, even across the Upper Midwest, as I outlined in my 2013 Tornado Forecast.
As severe weather cranks up to our south, more snow is on the way for the Upper Midwest. Rain is moving into southern Minnesota, and will continue to move towards the Twin Cities overnight. Most of the metro will see rain through tomorrow morning but some areas just north of the Twin Cities could see a some snow overnight. Rain will change over to snow for all of the metro shortly after noon tomorrow. This will be a fast moving system and most snow accumulations across the Twin Cities should end by midnight tomorrow. This storm will have a couple of challenges when it comes to producing heavy snow across the metro. These challenges include:
I believe the combination of these two factors greatly limit our heavy snowfall potential tomorrow. I have forecasted 3-6" for the
- It is now the second half of April and most of the accumulations in the Twin Cities will occur during the daylight. The combination of temperatures between 32-35º and the suns radiation being able to penetrate the clouds, will allow snow to melt, slowing accumulations.
- A moderate risk of severe weather is out to our southeast for tomorrow. A large line of severe thunderstorms will develop as the snow is developing to the north. These storms will produce very heavy rain and rob a good amount of moisture needed to the north to produce heavy snow.
Twin Cities but would not be surprised if most of the metro remained in the 3-4" range. The potential for higher accumulations exists from the north metro to Duluth. Some amounts of 8" or higher are possible around Lake Superior where lake enhanced snow can develop.
Today is the one year anniversary of what was the largest tornado outbreak in 2012. This year I'm staring out my window in the Twin Cities at our sixth straight day of accumulating snow. What a difference a year makes. It is mid April right?
It has been awhile since we've had this cold of a spring, especially across the northern plains. I, like many others are growing impatient this 'spring', and are tired of being bottled up inside. Many chasers are also growing impatient with the slow start to the storm chasing season. Chasers have grown accustomed to chasing in March and early April over the last several years. After a very low tornado season last year, some are wondering if we aren't headed down the same path this year. Through April 13th there has been only 188 preliminary reports of tornadoes. Our average is 355, meaning we are currently running 53% of normal.
Long range forecasting is a very difficult task, if not impossible at times. Most long range forecasts need to be taken with a grain of salt, but how do you get any better at them unless you try. The only way to attempt to forecast what may lie ahead, is to take a look at what happened in years similar to this one. I took a look at the main drivers behind our cold springs - the Arctic Oscillation (AO) and El Nino Southern Oscillation (ENSO). I will discuss what is happening with these features, years strongly correlated with 2013, number of tornadoes associated with these years, and my tornado forecast for the next two and a half months.
When beginning any long range forecast you have to take a look at the ENSO conditions. We have seen ENSO neutral conditions for the last several months and that trend looks to continue. SST anomalies are near normal across the Pacific Ocean, with one area of below normal temperatures off the coast of South America. If the below normal temperatures continue to expand we could end up in a weak La Nina by the summer. However, no significant changes are expected soon, meaning neutral conditions will continue through the spring.
Neutral conditions are difficult on long range forecasters because correlations to weather patterns are smaller than what they would be if an El Nino or La Nina were present.
The Arctic Oscillation (AO) plays a major role in temperature forecasting during the winter and spring months. The AO turns negative when a large, blocking, high pressure develops over Greenland. This allows cold, Arctic air to flow southward behind this high, through Canada and into the United States.
The AO has been negative for most of the winter, and very negative since the beginning of March. The weather across the U.S. has been dominated by strong cold fronts that push Arctic air south to the Gulf of Mexico. By looking at the map to the left you can see that much of the eastern U.S has been below normal, especially the northern plains over the last month.
Using the combination of ENSO neutral conditions and a strongly negative AO during the spring, I came up with four years that correlated well with this year. 1960, 1965, 1996, and 1997. I wanted to use as recent years so I threw out 1960 and 1965 for now, leaving me with 1996 and 1997. I wanted to find what the composite temperature anomalies were for March and April during these two years, and created the map below.
Look familiar? This map looks nearly identical to what we have seen in March and April so far this year.
Tornadoes of 1996-1997
The next step is to take a look where, and how many tornadoes occurred in these years. The map to the left shows an overlay of tornadoes from 1996 and 1997. These ended up being fairly active years with an above average number of tornadoes. Looking at rankings over the past 60 years, 1996 ranked 12th, while 1997 ranked 15th. These rankings also need to be taken with a grain of salt, as tornado reporting has drastically increased over the past 30 years, due to an influx of chasers and overall eyes on the sky. Many more tornadoes may have actually occurred during the 60s and 70s, but were either not seen or not reported.
There are a few takeaways from this image. First there was really only one big outbreak of long track, violent tornadoes that occurred during these years. This was the March 1st, 1997 Benton, Arkansas tornado outbreak. Otherwise long track tornadoes were very few and far between. This was also the case in 1960. Out of the four years I chose, 1965 was the exception to the rule. I'll have more on that below.
I also highlighted two areas where there was a higher concentration of tornadoes. This includes the western high plains from eastern Colorado through the Texas panhandle, as well as northeastern South Dakota through central Minnesota. Another similarity between these two years was when the larger tornado days occurred. Late May was the most active period of time during both of these years. These highlighted areas were filled with less destructive, shorter tracked tornadoes, but the overall number of tornadoes remained high.
Tornadoes of 1965
As I mentioned above, the one exception to the rule was 1965. This year was very active, and had it occurred more recently, I think tornado reports would have been much higher. This year was marked by several tornado outbreaks that featured a number of long track, violent tornadoes. This included the famous Palm Sunday tornado outbreak in the Midwest, the Fridley, MN tornado outbreak on May 6th, and several Nebraska tornadoes on May 8th, including the F-5 Primrose, NE tornado.
1960 had fewer large tornadoes, but similar to 1965 in one area. The big tornado days on the plains occurred in early May. This was due to the U.S. transitioning from winter to warm, humid conditions like the flip of a light switch. This will be one thing to watch closely this year, from the last week of April through the first two weeks of May.
So after researching what occurred in previous years, it's time to discuss what I think will happen in 2013. Even though the U.S. is off to a slow start, I remain optimistic for this years chase season. This is what I expect:
- It is likely we will see an average to above average number of tornadoes. This is good news for chasers following what was one of our lowest tornado years ever in 2012.
- May will be a very active month. We will need a sharp increase in tornado reports to reach an average number of tornadoes, and I believe we will see this spike in May. If this year remains similar to 96 and 97, the second half of May will be the most active.
- Activity increases for the western high plains. This area has seen several down years, with the last active year coming in 2007. There are many chasers who enjoy chasing from the Texas panhandle through eastern Colorado, and a return to patterns more similar to the 90s may be a welcome sight for many.
- I do not expect a large outbreak of long tracked, violent tornadoes. We are on quite a run in seeing one of these outbreaks every year for the last several years. I don't see a repeat of April 14th, 2012 at any time in 2013. If one does happen, it will occur in the first 10 days of May.
- There will be several tornado days featuring 20-40 reports. I expect a couple of these in May and one across the northern plains in June.
- June 17th will produce a severe weather again in Minnesota. Why not? It seems to happen every year.
Overall, chasers should remain positive. There will be plenty of tornadoes to see yet this spring. It may not be the be the massive outbreaks we have seen over the past few years, but still plenty of opportunities for photogenic tornadoes. Spring will finally arrive across the U.S. over the next 7-10 days, and it can't come soon enough.