Monday, October 31, 2016

Winter 2016-2017

While we work vigorously on an accurate 7 day forecast at KATV, there are others who spend much of their efforts with seasonal forecasts and I want to share two of them with you.  The science and reasoning behind them are sound, but we know how mother nature can have the last laugh.

The first I want to show you is the outlook from NOAA.  If you have been a long time reader of this blog, you know how much I don't like using them.  They really are not forecasts.  I don't know the best way to describe them other than "guidance".  They are broken down into 3 categories: below average, above average, and equal chances.  Those are then given a percentage to indicate a degree in confidence in what will happen.  

This along with other forecasts may not capture the full story.  What if a forecast calls for temperatures to be -1° departure from average.   That may not seem brutal, but what if extreme cold hits for 2-3 weeks while the rest of winter is a bit above average?  For example, December 2012 temperatures were +5.5°.  That's off the charts warm!  However, we all have a perception the month was horrible when a blizzard hit the state late Christmas Day knocking power out to 250 thousand people.  That was then followed by extreme cold for several days following.  But the first 24 days of the month were incredibly mild!  So please keep that in mind when looking at these forecasts.

It's important to remember these winter forecasts are based upon meteorological winter (December 1 through February 28th).  

Little Rock 30 year averages.

Snowfall 3.1''
Average winter high temperature: 52.6°
Average winter low temperature: 33.1°
Average winter seasonal temperature: 42.8°

NOAA says there is a decent chance temperatures will be above average for much of the southern and western United States with cooler than average temperatures near the Canadian border.  This outlook reflects the results of a weak La Nina in the equatorial Pacific.  There can and will be other driving factors this winter including the arctic oscillation which can not be accurately forecast more than 2 weeks out.
NOAA precip outlook does NOT show snow, but does indicate a higher likelihood of below average precip.  Remember, this does NOT mean it will not snow and we'll continue in a drought.   Hypothetically, what if you have 10'' of dry snow and the water equivalent is .5''?  That's below average precip and this outlook verifies.  So you see why you need to take this with a grain of salt.
As many of you know, I really like how Weatherbell.com meteorologist Joe Bastardi breaks down his winter forecast.  He's calling for temperatures to be average to -1° below average over the 3 month period.  The core of the cold will be focused across the Great Lakes and northeast while the west should be warmer than average.  This looks MUCH different than NOAA!!!!


What about snowfall from Joe and Weatherbell?  He has much of our region with below average snowfall, but since we only average 3.1'' per season, he will even admit the forecast for below average snowfall can be wrong.  We can go to sleep one night and get  3.1'' by the time you wake up in the morning, then it's melted by noon.  We know how that can happen around here.

One other worry I personally have is ice.  I'm not saying that's going to happen, but this is the type of winter it can happen in.  Also, while northeast Arkansas had a devastating ice storm in January 2009, the rest of us have not had one since the 1-2 punch in December 2000.  The law of averages are not on our side.  I don't like ice and I know many of you do not as well.    I would much rather have snow!  Once again, I'm not saying we will have an ice storm, but it's something worthy of keeping in mind.

Also, as we go into November and December, be aware of severe weather as we transition from warm to cold.  There are times our secondary severe weather season can be more active than our primary one in spring.

1 comment:

John said...

I'm sorry but I take what Joe Bastardi says with a grain of salt. All he ever does is make fun of NOAA, how the National Weather Service is wrong for putting out a forecast one certain way because he doesn't like it (i.e. percentages) and how he constantly gripes about the GFS and how the Euro can do no wrong. If he doesn't like the GFS then don't use it and don't offer it on Weatherbell. He's nothing more than a man in the private sector who wants to make as much money as possible, that's it. I will trust the forecasts any day of the week to the local National Weather Service Forecast Office out of Little Rock before using him. I also find it odd that you didn't post the NWS Little Rock Winter Forecast video/prediction on here which is specifically for Arkansas but use a guy who cares more about where he lives (Pennsylvania) and the northeastern USA. At least be fair and show both sides.

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