The Snow-Increase Website



Winter Wx Forecasts (HPC)


Watches, Warnings, Advisories (NWS)


Mesoscale Discussions (SPC)

(alphabetical order)

About the Author

Advisories and Warnings

Climate Change and Snow

Climate Change Websites

Climate Patterns

Duluth Local Influences

Heavy Snow Observations

How Much Accumulation?

Image Gallery

Informal Case Studies

Math and Computer Science

Mathematics in Meteorology

Microclimates / Mesoclimates

My Favorite Snowstorms

My Weather Definitions

Reading List

Snow and Convection

Snow Data and Climatology

Snow Impacts on Society

Snowfall Climatology

Training and Research

Winter Profiles

Winter Weather Processes


Above animation available at the ARG! Cartoon Animation Studio.

Numerical Weather Prediction (NWP)

Numerical weather prediction models are a key component of forecasting snow or any other kind of weather. They are more valuable if you understand how they are constructed and consequently their strengths and weaknesses.

Definitions of NWP

Glossary of Meteorology

NWP Process + Human Interaction

1. Data Collection
2. Quality Control of the Data Collected
3. Data Assimilation (Incorporate into the Model to Initialize the Model)
4. Numerical Forecast (Run the model)
5. Postprocessing of model output (ex: Model Output Statistics)
6. Human Forecast Using Model Output as Guidance
7. Evaluate Performance of the Model and the Human Forecast
8. Additional Research and Development

NWP Training

U.K. Meteorological Office

European Centre for Medium-Range Weather Forecasts

Meteorological Education and Training (MetEd) NWP Training Courses
These modules are especially useful for meteorologist interested in forecast applications.

Model Types and Classifications

Models are classified by the geographic scale of thier domain, size of features they can resolve, coordinate systems used to depict the data, and many other reasons. Here are some examples of model types:

Synoptic Scale (Several thousand miles)
Mesocale (Several tens to several hundred miles)
Local Scale (low end of Mesoscale and smaller than Mesoscale)
Storm Scale
Cloud Scale, Cloud System and Single Column Models
Short Range (0–48 hrs)
Medium Range (generally 48 hrs – 7 days)
Long Range (generally beyond 7 days)
Climate Models (more)
Hydrostatic (more from AMS Glossary of Meteorology)
Grid (data represented at points)
Spectral (data represented by a series of waves)
Nested Grid (Finer grid inside of a coarser grid)
Ensemble Systems (Multiple forecasts from different models or the same model)
Statistical Models
Boundary Layer Models – Definition of "boundary layer"

More specific definition of Mesoscale:
MetEd training module: “Definition of the Mesoscale”
AMS Glossary of Meteorology definition of Mesoscale

Examples Specific Models and Modeling Systems

Some of the models such as the WRF are not models in of themselves. They are modeling systems which allow one to tailor the construction of the model to suit different forecast and research needs.

WRF –– Weather Research and Forecasting Model
New NAM (WRF-NMM) –– North American Mesoscale Model
GFS –– Global Forecast System
AR WRF (or ARW) –– NCAR Advanced Research WRF
NGM –– Nested Grid Model
RUC –– Rapid Update Cycle
MASS –– Mesoscale Atmospheric Simulation System
SREF –– Short-Range Ensemble Forecast (SREF) System
MREF –– Medium-Range Ensemble Forecast (MREF) System
MM5 –– Mesoscale Model Version 5
NOGAPS –– Navy Operational Global Atmospheric Prediction System
ECMWF –– European Center for Medium-Range Weather Forecasting
UKMET –– UK Met Office
GEM –– Environment Canada's Global Environmental Multiscale Model

Technical Information for Specific Models

Weather Research and Forecasting Model (WRF)
Model Users Page
Model Users Page Workshop Presentations
WRF Overview: MetEd Presentation Short Version
WRF Overview: MetEd Presentation Long Version
MetEd Presentation: "Using the WRF Mesoscale Model"

Global Forecast System (GFS) – Model Documentation

PSU/NCAR Mesoscale Model (MM5) – Homepage