Tuesday, April 30, 2013

Rare May snow fall possible?

As flip the calendar towards May, you may be thinking that we are out of the woods for snow, right?  After all, the Twin Cities has seen nearly 18 inches of snow in April.  Well, I have some bad news for you.  Some snow is possible as a sharp cold front moves through Tuesday night, and ushers in cold Canadian air out of the northwest, where much of the country is still covered with snow.


We typically do not receive much snow in May.  The most snow the Twin Cities has ever seen during the month is three inches, which occurred three times.  Could this be a record setting year?  To be honest, it going to be a close call…too close.  It will all depend on where the snow band sets up, and placement of the rain/snow line.  The jet stream is setting up over northwest Minnesota by Wednesday night.


The Weather Prediction Center seems to believe that the likelihood of a couple inches of snow or more sets up across the southeastern Twin Cities metro into southwest Minnesota, including Rochester.


The two major American weather models tend to support this notion from the overnight runs on snow placement.  The NAM model overdoes amounts, but it represents where the heaviest snow will fall.  The GFS is a bit more in line realistically with amounts, and depicts snow amounts in the same general area.





The European model, which as of late tends to be the most accurate because of it’s ability to resolve data, shows the snow band from Duluth to the northwestern Twin Cities suburbs, to Sioux Falls, South Dakota.  At this point, I tend to believe the European is the outlier.


I think the Twin Cities will see a mixture of rain and snow Wednesday into early Thursday.  The question on accumulation is if we see a changeover to one precipitation type (p-type) during the event.  Still too early to pinpoint precise snow totals, but hopefully tonight will shed a bit more light.  Southeast Minnesota will definitely see snow accumulations.


Monday, April 15, 2013

Minnesota Severe Weather Awareness Week 2013

This week is Severe Weather Awareness Week in Minnesota.  While we have been plagued by snow and cold lately, now is a good time to prepare for severe thunderstorms as we head towards the summer months.  On Thursday, there will be a statewide afternoon and evening tornado drill at 1:45 and 6:55 p.m., respectively.

An understanding of basic terminology is fundamental for severe weather safety.  Here are some terms you will see in the media, from the National Weather Service, and on this blog:

The Storm Prediction Center issues an outlook leading up to when dangerous weather is likely.  These outlooks may be issued as far out as eight days prior to the event.  For a better understanding of these outlooks, this post does an excellent job explaining the Storm Prediction Center products in-depth.

When conditions become favorable for organized severe thunderstorms and/or tornadoes to develop, a watch is issued by the Storm Prediction Center.  It means weather conditions are favorable for dangerous weather to occur. In other words, a "watch" means watch out for what the weather could do, and be ready to act accordingly. You may wish to alter or have a back-up plan for any outdoor activities or travel.  A typical watch duration is six to seven hours, but it may be cancelled, replaced, or re-issued as required.

A warning is issued by the local National Weather Service office when the weather event is imminent or occurring somewhere in the defined warning area, and that people need to take shelter as soon as possible.  These warnings can last as long as 45 minutes to an hour.  New to 2013 is the use of “impact based warnings” by the National Weather Service to emphasize threat and impacts to improve public response.  More information can be found in the video below:

Do you have enough “safety nets” in place for receiving these weather alerts?  Every person should have multiple means other than the outdoor warning sirens for being aware of approaching severe weather.  As I have stated many times before, sirens are only meant to be heard OUTDOORS as a means to get inside a sturdy structure when sirens are sounded.  In addition to the outdoor siren, conventional NOAA Weather Radio should be in every home, much like smoke detectors.  These radios can be set to alert you in standby mode to all or certain hazards within a county or counties, especially during hours of sleep.  It also provides general weather information 24 hours a day, seven days a week.

Many cell phones now feature the ability to receive Wireless Emergency Alerts (WEA), which allow push notifications when the user is within range of an affected hazard area. There are still compatibility issues with this system, mainly with AT&T’s new high-speed LTE network, so I can not recommend this system at this time until it works with all of the phones on the market.  For those who are unable to benefit from WEA, here are a couple apps which work nicely:

I personally prefer iMap Weather Radio as it allows selectable alerts from virtually every weather hazard possible.  Another benefit is that it uses GPS tracking to only alert when the phone is within the watch, warning, or advisory boundaries, unlike NOAA Weather Radio, which is currently limited to entire counties.  This app also features basic radar and Storm Prediction Center outlooks.  For $9.99, it is a bargain in my opinion considering the cost of weather radios run $30 or more.

Some tornado statistics.  From 1950 to 2010, Minnesota averaged 27 tornadoes a year.  Over 75% of the tornadoes during that period occurred in the months of May, June, and July.  The majority of tornadoes happen between 4 and 6 p.m.  When it comes to tornado intensity, Minnesota tornadoes tend to be on the low-end, with more than half being F/EF-0 and F/EF-1 strength.  The last F/EF-5 tornado in the state was in June 1992, affecting the southwestern town of Chandler.  An Enhanced Fujita scale table is found here.

If you have any severe weather or safety questions, please post them below!


Sunday, April 14, 2013

Is Spring around the corner?

Winter has extended it’s stay into April with 6.6 inches of snow having fallen already this month officially in the Twin Cities, with much more across western and northern Minnesota.  Another 2.7 inches needs to fall in the Twin Cities to crack the top 10 snowiest month of April. If there is any silver lining, April snow typically does not stick around long as the sun angle and radiation for this time of the year is able to erode at the snow pack.  Where recent snows have been the heaviest, a foot or more still exists north of the Highway 23 corridor.


Another episode of never-ending wintery weather is on tap as a low pressure system will move out from the Rockies and into Minnesota today into early Monday. 


North of the low is where heavy snow will occur. Across the Red River Valley is where 6 to 10 inches of snow is possible.  This is an area that does not additional precipitation as major flooding is forecasted for the area.

South of the low is where rain will be found as somewhat warmer air is trying to make it’s way into the southern portions of the state.  The models have been consistent at indicating a chance for freezing rain as temperatures hovering around the freezing point.  The Weather Prediction Center shows high probabilities of this occurring across central and south central Minnesota.  This could make morning roads a bit slick for travel, before we see a change-over to rain for the afternoon.


Radar showing the rain marching northward across southern Minnesota.  Rain being reported across south central Minnesota with some mixed precipitation in the Rochester area.  Snow is falling across the southern Twin Cities metro.


Turning the page?  Recent model trends have indicated a chance of 60 degree weather across southern Minnesota to close out the month.


We just need a little patience as these temps are still a couple weeks out. We will have to see if this holds up. Models this far out have a tendency to fluctuate a bit. At some point we have to warm up!