Forecasting Techniques By: Mike Vuotto and Jake Mulholland

Step 1- Look at current observations -check current observations for temperature, dew point, relative humidity, cloud cover. -look at current satellite loops using the visible or the infrared. -look at current radar loops to see where precipitation currently is and where it is moving to. After checking the above, then you can go to the SPC Meso-analysis page to check current data as well… only thing with this is that the analysis uses model data from the RAP model for wind data and height lines.

Step 2- Open the forecast models -Once you have a good sense of what is going on with the atmosphere then you can look at the models. -Some tools to use: Proaccuweather, Rap weather site, weathertap.com , Bufkit, MesoWest, SPC Meso-analysis page, Penn State e-wall, Skew-t log-P diagrams, Model Output Statistics (MOS). In Meteorology, the atmosphere is looked at from the upper levels to the surface level, therefore…..

200-300 mb level Use this level to get a good sense of where the strongest winds aloft are…. Gives a good idea of where the jet stream is. Where the jet stream is.. is where you can expect the most active weather to be. From there we go to the 500 mb level…..next slide

500 mb level Use this to get a good sense of where there might be a ridge or a trough. The higher decameter lines indicate higher heights… which concludes that warmer weather will likely be present there. Opposite is true for the lower decameter lines.. the lower the height lines will indicate cooler weather and even where active weather might be present. Look for Vorticity- measure of the rotation rate of a small fluid element in a flow field.

500 mb cont. Where you have vorticity.. There will most likely be some kind of weather element going on in this region.. In the summer you don’t need much vorticity to get thunderstorms to erupt whereas in the winter you would need much more. These vort maxes are embedded in shortwaves- a shortwave is what we look at to see if there will be active weather or not. When heights start to fall especially rapidly , expect there to be active weather. These usually appear as little kinks in the height lines. -This is one way of answering WHY the model is predicting QPF for the surface… always use this to answer the question as to why the model is prediciting precipitation.

700 mb level Use this level to determine where the most moisture through the atmosphere is located. -Really dry air aloft is a good sign that their will be no rain or even clouds -Look at this level to determine if there will be cloud growth… moister it is the more likely for clouds and precipitation.

850 mb Use this level to determine where the rain/snow aloft will be. On a bright sunny day, usually in the warm season (spring and summer and into the early fall), you can use this level to get the high temperature at the surface for that day. Doesn’t always work but general rule of thumb is to add 15˚C to the temperature at 850mb and that will be your possible afternoon high for that day.

850 mb cont. Also, for lake-effect use this level because if there is a 13˚C difference between the air and water temperature- good possibility for lake-effect as long as all the other parameters are true as well. Will show what I mean by all this when I show the ProAccuweather site.

Surface Look for QPF output- most likely where there is QPF output, there is the likelihood for precipitation in that area. You can back-up why there is QPF output by looking at the levels higher up in the atmosphere. Use this also to look at the height lines- the higher the numbers, usually means warmer air and the lower the numbers, the colder the air. Show Accuweather pro- Username: oswego Password: sunny

Bufkit Is very useful to see the vertical profile of the atmosphere because it basically gives a forecasted sounding for that point in time. When the temperature line and the dew point line are close together, expect there to be clouds and even precipitation. Will show the students how to go about using this tool.

Twisterdata.com Very useful for severe weather…. gives a forecasted sounding but it is more useful because you can just click on a point and it will give you the sounding for that location. Also, gives, CAPE, helicity, and other parameters needed to predict severe weather.

SPC- Storm Prediction Center Very useful tool- the Meso-Analysis page is an extremely useful tool to forecasting especially because it gives you the current conditions… However, be warned that the wind barbs and the isobar lines are actually model data from the RAP model.

MOS- Model Output Statistics Very useful in the summer and winter months In the spring and fall, MOS tends to have trouble handling certain features such as temperature and dew point.. Mostly due to the fact that equations go into these statistics and they change with the seasons.

Penn state E-wall Good to use because you can access the Hi-Res NAM at 4km grid spacing. Gives you the model output for mainly east of the continental divide. Gives temperature, precipitation output, and 850 mb wind barbs over a grid spacing. Helps to forecast temperature for an area easier. Can access the EURO as well