Hello everyone interested in the Iowa Caucus!
It is early to be thinking about weather forecasts for the evening of February 1st, but I thought I would post this to get you thinking about weather and how it may affect the caucus goers. I’m not from Iowa, but I know a little something about computer models for weather forecasting.
In case you don’t want to read this entire blog entry, here is a quick summary…
At this early point, it would appear temps may range from mid 20s in northwestern Iowa to mid 30s in southern counties when the caucus starts. It looks mostly cloudy with some light snow breaking out over portions of the state. Stay tuned for updates as we get closer to Feb 1. I’ve added the weather.com forecast at the bottom of this diary.
Forecasting more than 7 days ahead of an event has a great degree of error, so expect this to change. I hope to post updated model data and other forecasts as we get closer to the caucus.
First, here is some help understanding this model output. At the top left you see a date followed by 12 UTC. This is the date and time the model output was created. In this case, this model was run at 6am central time on Sunday, Jan. 24th. We know it is 6am because the 12 UTC refers to the Coordinated Universal Time which was called Greenwich Mean time and is also known as Zulu time. Subtract 6 hours to get US central time. As a hint, the 12 UTC and 00 UTC model runs use the most data from around the world, so they tend to be a little more accurate than the 18 UTC and 06 UTC runs.
Models are run every 6 hours.
12 UTC is 6am central
18 UTC is Noon central
00 UTC is 6pm the day before the date shown
06 UTC is 12am
This map shown is a forecast for 204 hours from 6am Sunday, Jan 24 and is valid for 00 UTC time on Feb 2 which equates to what time? This is a test...the answer is 6pm on Feb. 1.
Now, lets look at the data on the map. The blue and red lines represent temperatures just above the surface. These are given in 10 degree Celsius increments. The blue line going through southern Iowa is 0 C which is 32 degrees F. (You do see Iowa, right? The black lines show the United States with the states outlined. Other black lines show lines of equal pressure and wind barbs to show wind direction and speed)
The green shows accumulated precipitation is liquid inches during the previous 6 hours. The green band stretching over Iowa represents a small amount of precipitation (between 0.01 and 0.1 of an inch) in the previous 6 hours. An average snow to rain ratio is .1 of liquid = 1 inch of snow. (assuming it doesn’t melt upon landing)
I’ve looked at this model going through time and it suggests this light snow is forming during the afternoon on Feb 1 and becoming a little heavier overnight once the caucus is over. It is important to note, the model is currently NOT showing a snowstorm….just some light snow with a light east breeze.
I hope to have updates in the days closer to the caucus. Whichever candidate you support, plan for temps in the mid 20s to mid 30s range with a little light snow on Caucus evening.
The National Weather Service doesn’t forecast beyond next Saturday (2 days prior to the Caucus), so we don’t have them to use yet. Weather.com’s forecast for Des Moines shows snow and rain showers forming on Caucus day becoming all snow showers that night. They are expecting 1 to 3 inches of snow for central Iowa by that night. High on that Monday is forecast to be 34 with the night’s low at 29.