Step 1: Use the navigation bar label “Current Forecast” for most recent forecast. Or use the calendar to obtain your FORECAST date of interest. (NOTE: available forecasts are denoted by links).
Step 2: Note the DATE and DISEASE LOCATION at the top of each forecast.
Step 3: Page down and review the REGIONAL and TRAJECTORY WEATHER.
Step 4: TRAJECTORY CONFIDENCE is based upon the forecaster’s assessment of atmospheric complexity pertaining to that case and his/her forecasting experience.
Step 5: Study the OUTLOOK carefully. The likelihood of disease development along the forecast pathway/trajectory is based on several things: weather favorable for sporulation at the source, survival of the spores during transport, and rain/favorable weather for spore deposition and plant infection. You should ALWAYS take into consideration your local weather and conditions.
Step 6: Look at the horizontal map showing the trajectories. The SOURCE location is indicated by a black star. Latitude and longitude coordinates of the source are given on the left margin of the map. Review the horizontal map showing the spore cloud trajectory for 1-3 source height(s) in meters (m). Time/position nodes show equal time segments along the trajectory (48+ hours). The small graphic below the horizontal map shows the vertical movement of the spore cloud center for the 1-3 source height(s); it moves forward in time from left to right. Time nodes in the vertical graphic correspond to those in the horizontal map.
Each Soybean Rust Forecast includes descriptions of factors pertinent to the disease situation, a general outlook assessing the risk of disease development, and a map showing the spore-laden wind flow away from an active source or source region (i.e., a cluster of closely-grouped counties) using multiple, centrally-located trajectories.
The maps show the motion of floating particles (spores) that originate in the atmosphere from 1-3 selected heights above the source on the date and at the time given in the map headings. The heights are color coded red, blue, and green. Red is the lowest release height above the source, blue is at a higher height, and green is the highest height of particle release. If there is only one trajectory forecast, the color code is red. The larger upper map shows the horizontal motion; the small rectangular lower map, the vertical motion. If you imagine the particle to be at the center of a spore cloud, then the forecast trajectory indicates the future pathway of the center of that spore cloud. The release time is in Universal Time on a 24-hour clock, and will be set to correspond to about 10am or 11am local time. A black star denotes the starting point for the trajectory (exact latitude and longitude are written along the left-hand side of the map). After the trajectory starts, there are time/position markers along the forecast pathway. The larger symbols are the 00Z (00 UTC) markers, which corresponds to 7pm EST or 8pm EDT. In the headings, the SECOND line has the start date and time for the forecast trajectory. Along the bottom of the map there is some information about the atmospheric transport simulation. If you have any questions, please contact the NAPDFC.
The Regional Weather section gives a broad view of the weather conditions existing immediately prior to and during the forecast period. Notes on jet stream winds, approaching fronts, temperatures, etc., will be found here.
The Trajectory Weather section focuses on the conditions near the forecast track of the spore cloud center. This information is specific to each trajectory.
Trajectory Confidence describes the general quality of the forecast pathway calculations, using the ratings of Low, Medium, and High. With continuing improvements to the HY-SPLIT model, most ratings will be High. Sometimes there are combination ratings, such as, “High first 12 hours, then Low”, but there is never an improvement from the initial rating. However, even the Low-rated trajectories may be helpful.
The Outlook portion of the Forecast combines all the biological and meteorological elements into an evaluation of the risk of disease development associated with that source or group of sources. The Threat is given first. This describes the source's potential contribution to the spread of the epidemic. The given threat rating is color coded corresponding to the likelihood of infection. Red represents the greatest risk, followed by blue and then green. Risk Assessments and the factors pertinent to potential disease development due to that source follow the Threat. These factors include sporulation at the source, survivability of the airborne spores, possibility of future deposition, opportunity for infection, or other information that would enhance the understanding of the forecast.
For more information visit our Threat and Risks page.
THINGS TO REMEMBER: The forecast trajectories and the resulting Outlooks can vary from reality in a number of ways. They will be most useful if you keep in mind the following:
- Sporulation occurs at night and the spores are released anytime from 8 AM through 1 PM. The trajectory start at 10 AM is just before maximum spore release. However, spores released at other times of the day may follow other tracks, especially if the weather situation is changing rapidly.
- The pathway you see on the map is the anticipated path for the spore cloud CENTER. The spore cloud will actually spread away from the center. The areas on either side of the trajectory pathway will also be vulnerable.
- There is a limit to the detail and accuracy of the weather forecasts. If you are in a potentially high risk area, be sure to pay close attention to your local conditions!
- Finally, these forecasts may also be viewed from a different perspective. They can't tell you exactly where the spores will go, what the exact weather will be, or if you'll definitely receive viable spores deposited on your fields. They can, however, do a very good job of telling you where the spores WON'T go, what the weather WON'T do, and when you likely WON'T have to worry about the inoculum arriving in your fields from known sources. This information should be helpful in making decisions about control strategies using protectant fungicides.
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