I get excited about the weather, like many skiers, but I am no meteorologist. However, I know that there is a lot of information, and misinformation, out there and I want to share the resources I use to make wildly speculative inferences about the weather. You can use them too.

Most of the information here comes from weather models. Weather models give us a decent idea of what the weather might be in the long term (i.e. whether it will be warm or cold in a week, or stormy or calm), and short term models help us to pinpoint smaller-scale weather features and timing. Here are models and model information, in a generally descending format from longest-range to shortest-notice. There are a bunch of different outputs from the models, especially in the long range (many having to do with aviation such), but we’re only interested in a few, namely:

• 850 mb temperature. This is the temperature about 5000 feet up in the air. Above 0 C is bad. Below 0 C is better. This does not correlate necessarily with the temperature at the ground, however
• Surface temperature. This is the temperature at the surface. Got it? 850 mb and surface temperatures sometimes come in to play when discussing precipitation type (i.e. rain, sleet, snow).
• 1000-500mb thickness. This is a pretty good indicator of whether it will snow or rain (or be warm or cold). 540 is the magic number. Rain > 540, Snow < 540. With some but not too much variability. Cold air is denser, so the thickness is lower. Much more information here.
• MSLP, or mean sea level pressure. This is an output showing highs and lows, which correlate to storms.
• Period precipitation. Models usually show precipitation over three- or six-hour periods. Most models have a map showing thickness and precipitation overlaid (and usually MSLP, too) so you can see a) where there is moisture and b) where it’s cold enough to be snow.

A couple notes. Models have numerical output (tables) and graphical output (maps) and I’ll link to whatever I can. Models cycles are updated based on UTC or Zulu (Greenwich Mean) time (usually 00Z, 06Z, 12Z, 18Z), but that doesn’t necessarily correlate with their availability. I’ll mention that. Also, all the abbreviations mean something. No one really knows or cares. Oh, and beyond seven days models vary immensely from run to run, and whatever you can glean from them is, well, not that useful. But fun! On to them:

• The GFS is the long-range US government model. (And, since it’s the work of the government, it is free! Your tax dollars at work.) It goes out 384 hours, or 16 days. The model itself is here, and a numerical output can be found here. (The link is for Hayward, but replacing KHYR with any other airport, like KMSP, will give data for there.) I usually look at the 100_500_thick link on the model page, and you can then select “loop all”. The GFS is updated at 5 and 11 a.m. and p.m. (all times Central Standard Time; models don’t go on daylight time in March, however).
• The GGEM is the Canadian’s model. It’s updated twice a day around noon and midnight. The 00Z model run goes out 10 days, and the 12Z goes out seven. Maps can be found here. I generally look at the precipitation output (which includes the 540 thickness line) and the total accumulation. Remember, it’s Canadian. Everything is metric.
• The ECMWF is the European model. You have to pay money to get that one, and I don’t. However, you can compare it with the GFS for free here (you want the surface pressure comparison), which is a good way to at least see if it’s showing something similar or if it is wildly different. Or, here’s another site I just found. Look at the North America images. The ECMWF updated a bit before 2 a.m. and p.m.
• The DGEX is a US model which has some interesting outputs, like 6-hour snowfall and total snowfall, which are all available here. It runs from 84 hours (when the NAM, see below, ends) to 192 hours (3.5 to 8 days), and comes out on the 06Z and 18Z cycles, around 6 a.m. and p.m. I also look at the SLP/6 hour precip, which includes the 540 thickness.
• The NAM runs to 84 hours and has similar attributes to the GFS, but is much finer in scale. Find it here.
• The WRF model goes to 36 hours here, but I don’t check it often.
• The HRRR is updated every hour and goes for 15 hours here. Before or during a storm event it is fantastic. It has really interesting attributes and outputs. I’ll mention it more if a miracle storm is upon us.