As local weather is in taste of Spring mode, now is a good opportunity to look at snow forecasts elsewhere in the country that have gone wrong. People in Georgia may have the impression that snow and ice forecasts only go wrong here. The truth is even up North in the dead of winter, where cold air is not even in question, busted forecasts for snow/ice still occur with regularity.
The reason? As covered in prior blog posts, to get snow conditions have to be perfect and the margin between yes and no is insanely small.
A snow forecast is relatively easy ONLY if you’re in the middle of a cold enough air mass, and in the bullseye or “heart of the path” of a winter storm. If you are near the edge of a system, or have only marginally cold air the forecast has high bust potential.
Areas near mountains or coastlines are more difficult than in the center of the country because both mountains and Oceans interfere, and can change temperature and moisture at the last minute in ways difficult for models to capture.
EXAMPLES OF FORECAST VS REALITY FROM THIS MONTH:
IN REALITY, Southern Wisconsin only ended up with a dusting to zero, and Chicago and Northern Illinois only ended up with around half an inch while the 1-3 fell South of expectation across Central Illinois:
Great job in the middle of the storm, but as is typically the case, near the edges accuracy drops way off in reality:
Some places in North and NE Indiana got more than expected areas of South-Central and South Indiana ranged from more to less than expected. This is normal, unfortunately Atlanta is almost always on the edge of winter systems not smack in the middle. We get interference from the Gulf, the mountains and the Atlantic Ocean.
Below is where snow fell in our region on January 29th with the cold front:
FORECAST VS REALITY OHIO TO PA, WEST VA AND DELAWARE:
The forecast was bad in Ohio and most of Pennsylvania and Delaware, it was good only in far South PA and the WVA mountains. Way too much was forecast in most areas which got only a coating or an inch, while Maryland and Delaware got 1-2 more than forecast.
A FORECAST LESSON FROM THE NORTHERN PLAINS:
In any snow/ice forecast there is actually a range of possible outcomes which is known to forecasters while the public just thinks of one possible outcome, usually rooting for the highest number lol. Let me show you...
Here is a snow amount forecast from up North just a couple days ago:
4-8 inches is forecast for the Northern reaches with 1-4” forecast for the Southern areas of the storm.
But, but but but... There is actually a forecast range from the least amount (bust) to the (boom) or worst-case scenario shown below:
So the range on the LOW end of REALISTIC EXPECTATION is 0-4 inches, while the HIGH end of realistic possibility is 6-10 inches.
Say you are forecasting for or live in or near Watertown, Sioux Falls, Sioux City, Norfolk, or Minneapolis. Here is your forecast snow amount with this storm, 2 inches for Watertown nothing for those other cities:
HOWEVER, here is the known forecast RANGE OF POSSIBLE OUTCOMES from low to high:
So Watertown in reality of the forecasters known data could get not a flake or 4 inches, Minneapolis zero OR 1 inch, Sioux Falls/Sioux City and Norfolk zero OR 1-2 inches. Remember in the FIRST map of the three above, the forecasters did not give a range but just put out a forecast of their BEST ESTIMATE, even though they know the range includes much less and much more. Meteorologists know this, it’s time the public did, too.
Now you do. If you’re a long time reader of my blogs you knew this decades ago. Spread the word.
Here’s what mother nature decided to do in the case above:
Watertown got an inch or so while the other cities we talked about got nothing on the ground but saw snow flurries, the 4-8 inch amounts stayed well to the North and West of where we looked. Remember, this was the forecast:
A good forecast for the Northern most areas which were in the bullseye or “heart of the storm path” like North Dakota and most of Northern Minnesota. Too much was forecast further South as well as in NE MN, Northern Wisconsin and Upper Michigan!
The real world of weather is so much more complicated and complex than the models on our computer or the visions in our heads.
Unless the forecast is perfect for “my backyard” the only thing that can be counted on is: