Atmospheric River Forecast Products
This page contains graphics designed to forecast the presence and strength of Atmospheric Rivers using data from the NCEP Global Forecast System (GFS), North American Mesoscale Forecast System (NAM), and Global Ensemble Forecast System (GEFS) models. The GEFS products are produced by Dr. Jason Cordeira at Plymouth State University as a cooperative effort with CW3E.
NCEP Deterministic Model Forecasts
IWV, IVT, and Time-Integrated IVT Click on an image to see forecasts out to 180 hours from the GFS and NAM
Integrated Water Vapor Transport (IVT) and Relative Humidity GFS Meteograms
These meteograms illustrate the forecasted conditions over a given locations for the 3 or 7-day forecast period from the GFS. The top panel includes IVT in each layer (kg m-1s-1) or relative humidity (%) shaded with the 0°C isotherm contour and wind barbs(m/s), gray shading indicates location elevation. The middle plot illustrates the 3-hour precipitation represented by the bars, total 72-hour precipitation, height of the 0oC isotherm, and location elevation. When the freezing level is below the location elevation, line and bars are blue representing the likelihood of snow and when the freezing level is above the location elevation line and bars are green representing the likelihood of rain. The bottom plot illustrates the IWV and IVT, as well as the presence of AR conditions shaded in gray. The yellow dot on the map indicates the location of the current plot. Click here to view Alaskan domain
Select Type of Meteogram, Latitude and Longitude to generate plot. Click image to open in new tab.
Integrated Water Vapor Transport (IVT) GFS Cross Sections
These cross sections illustrate the forecasted conditions along a longitudinal line from 25-65°N for the given forecast time from the 0.25° GFS model. The top panel shows IVT in each layer (kg m-1s-1, shaded), the 0°C isotherm (contour), and wind barbs (m/s) and the bottom panel illustrates the IWV and IVT. The dashed lines on the bottom panel illustrate thresholds for AR conditions. The map on the left shows the location of the cross section as well as the IVT (kg m-1s-1) at the forecast time from the GFS. Gray shading indicates the presence of AR conditions (IVT >250 kg m-1s-1 and IWV >20 mm). Place your mouse over a forecast hour for a given longitude to see the cross section or click to open in a new window.
Select Longitude and Forecast Hour to generate plot
West Weather Research and Forecasting (West-WRF) Model
West-WRF is not currently running in real-time in an effort to improve the forecast skill through validation and verification. CW3E will resume real-time forecasting using the West-WRF prior to the next cool season. Below is a series of example forecasts from the West-WRF prior to an AR landfall in April 2018.
Integrated Water Vapor (IWV) Click on an image to see forecasts out to 180 hours from the GFS and NAM
Integrated Water Vapor Transport (IVT) Click on an image to see forecasts out to 180 hours from the GFS and NAM
NCEP Global Ensemble Forecast System (GEFS)
U.S. West Coast AR Landfall Tool Courtesy Jason Cordeira, Plymouth State University
The probability CW3E AR Landfall Tool displays the likelihood and timing of AR conditions at each point on the map in a line along the U.S. West Coast or inland derevied from the NCEP GEFS model over the next 7 or 16 days. The probability of AR conditions represents the number of ensemble members that predict IVT to be greater than the chosen threshold at the given location and time. To see how each forecast type has changed over the previous seven days click on dProp/dT. These plots are created by Jason Cordeira, Plymouth State University.
Select variable or threshold to be displayed, location, and forecast length to generate plot, click image to open in a new tab.
U.S. West Coast IVT Plume Diagrams Courtesy Jason Cordeira, Plymouth State University
The plume diagrams below represent the integrated water vapor transport (IVT) forecast for each of the 20 perturbed GFS ensemble models (thin gray lines), the unperturbed GFS control forecast (black line), the 20-member ensemble mean (green line), and the maximum ensemble value at that forecast hour (red line) and minimum ensemble value at that forecast hour (blue line). The white shading represents the +/- 1 standard deviation forecast from the ensemble mean. The yellow dot on the map indicates the location of the current plot.
Select forecast length of plot and coastal location to generate plot. Click image to open in new tab.
IVT Ensemble Probability Plots Courtesy Jason Cordeira, Plymouth State University
Select forecast hour, threshold, and domain to generate plot. Click image to open in new tab.
IVT Thumbnail Ensemble Plots Courtesy Jason Cordeira, Plymouth State University
Select forecast hour and domain to generate plot. Click image to open in new tab.
The above images display the 20 members of the GFS ensemble; each thumbnail shows IVT (kg m-1 s-1) magnitude shaded according to scale and IVT vectors.