|INTRODUCTION TO MODEL MOS
METEOROLOGIST JEFF HABY
MOS stands for Model Output Statistics. They are an integral part of putting together a specific
and precipitation forecast. In fact, just about every forecaster will use MOS to help with their forecast.
Forecasters that do not use MOS are at a huge disadvantage to those that do. If you are using the
NWS forecast, that forecast is likely being made from a forecaster developing a specific forecast by
using MOS and their forecast intellect. What I do is treat the NWS forecast as another model. I will
write down the forecast from each model MOS and the NWS. Then I will develop my own conclusion from looking
at weather data and models and integrate that with the guidance from the models and the weather service.
The NWS forecast can be obtained from the following link below. Click "graphical" next to the
state of interest.
I want to share a website with you that is the best website ever made when it comes to learning
about MOS and retrieving current MOS data. This website is from NOAA. The website is below:
This website is the best because it has all the important MOS you need and it is easy to see all the MOS
from a certain location at the same time. To see all MOS from one location open the website above. Next,
click the link that states, "One-Stop MOS". Pick by checking in the box the location(s) you need MOS
for. What is great about this
also is that it gives the station ID and a list of stations by state in alphabetical order. Once you
have checked the MOS you want then scroll to the bottom and press "submit query". What is
not to like? wow!
What is also fantastic about this site is that it gives the complete interpretation of the MOS
from each of the models. To see this, go to the link above. The primary forecast models are
the GFS (Global Forecast System) which is the renaming of the AVN model (Aviation) / MRF model
(Medium Range Forecast) and has
MOS called MAV, the Eta which is based off the NAM model (North American Mesoscale) and has MOS
called MET, and the NGM (Nested Grid Model) which has MOS called FWC (Forecasted Weather Conditions).
Under each model you will see a link called "Description". Print that information out for each model.
It has the information you will need for decoding the MOS for that particular model. The primary data
that will be examined from a MOS are temperature forecasts, POP (Probability of Precipitation),
QPF (Quantitative Precipitation Forecast), and High temperature (daytime) and low temperature (overnight)
each day. There is also cloud cover, visibility, and wind information. In winter weather or
thunderstorm situations it is important to study the POP of thunderstorms/ severe thunderstorms,
precipitation type forecast, and amounts of winter precipitation.
Examine the MOS each day for your forecast location. Compare how well each models MOS verifies
for the particular weather situation each day. Use the MOS as a guide to your forecast process.
Once you understand MOS and you go through the rest of the forecast trick essays then you will get
knowledge of how you can outforecast MOS.