144 captures
15 Jan 2006 - 11 Jun 2015
About this capture
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:
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.











NCEP WPC and SPC
SREF (MODEL) DERIVED
WINTER WEATHER IMPACT GRAPHICS
Prob %
 
Click any button below to begin viewing images.
AREA:  AK CONUS
 
Forecast Hour
Loop  03  06  09  12 
15      18  21  24  27 
30      33  36  39  42 
45      48  51  54  57 
60      63  66  69  72 
75      78  81  84  87 
Probability of Significant Impacts
Surface VisibilityRate (Intensity)Duration
 ≤1/2 Mile1"/hr12 hr
 ≤1/4 Mile2"/hr24 hr
 ≤1/8 Mile3"/hr48 hr
 
Probability for Other Impacts
 
Accumulation on RoadsZR ≥.01"Blizzard Criteria

Exceedance of NWS Winter Storm Watch/Warning Criteria
12h SnowZR
24h Snow

Mean Event Total Accumulations
Combined S/IP ZR
 
S/IP

ZR
ABOUT THESE GRAPHICS
EMC's SREF HOME PAGE
WPC's Winter Weather Forecasts
WPC WWD Model Diagnostics
CONUS radar and current watch/warning loop
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
QUESTIONS?  See the help page or send questions to WPC's Webmaster.