Short-Range Ensemble Forecast (SREF) Derived Winter Weather Impact Graphics
This page displays automated SREF-derived probability graphics for winter weather event attributes considered significant to the public. They are designed to address the aspects of winter weather events beyond accumulation - specifically duration, timing, and intensity. Additional probability graphics provided are directed at assisting a NWS forecaster during the winter weather forecast process.
Please note the following:
The image content is derived strictly from SREF output (21 members - 3 hourly output out to forecast hour 87). There is no forecaster intervention to the probabilities displayed.
The SREF is run four times per day, initializing at 03Z, 09Z, 15Z, and 21Z. Images on this page will always represent the latest available guidance. Data is typically available approximately 4-5 hours after initialization (i.e. the 15Z SREF images should post by 20Z).
All forecast times are in UTC (Z). If you'd like to know how UTC (Z) relates to your local time, click on this conversion table
Viewing the forecast graphics
Please use the menu on the right-hand side of this page to begin viewing the graphics. Clicking on any button will automatically remove the text in this window and replace it with a single graphic or forecast loop.
The following are set as defaults initially:
- Area - CONUS (contiguous United States).
- Forecast Hour - Loop. If chosen, a loop of forecasts from 3-87 hours (in 3-hour time steps) will load.
- The probability that the winter precipitation rate will reach or exceed 1 inch per hour.
Note that if you wish to view the default options, simply click on one of the already selected buttons.
Once a single graphic or loop is loaded:
Images can be zoomed by clicking the ZOOM button, and then left mouse-clicking on the image. While in ZOOM mode you can roam or pan around the image by dragging the left mouse button. Revert back to the original image by clicking RESET.
Probability for Other Impacts
Exceedance of NWS Winter Storm Watch/Warning Criteria
Mean Event Total Accumulations
Options available while viewing images:
ZOOM - Click the "Zoom" button, then repeat LEFT click
UNZOOM - Repeat RIGHT click on image or click the "Reset" button
PAN - Drag left button while zoomed