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Soaring Weather Forecasting for Dummies

Soaring Weather Forecasting for Dummies. SOARING WEATHER FORECAST SIMPLIFIED Ramy Yanetz August 2018. Agenda. Real World techniques for using simple forecasting tools Emphasize will be on how to use these tools to maximize XC soaring results

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Soaring Weather Forecasting for Dummies

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  1. Soaring Weather Forecasting for Dummies SOARING WEATHER FORECAST SIMPLIFIED Ramy Yanetz August 2018

  2. Agenda • Real World techniques for using simple forecasting tools • Emphasize will be on how to use these tools to maximize XC soaring results • It is *not* about understanding the science behind the forecast and the weather • Common mistakes • Will discuss the following forecasting tools: • NWS forecast discussion • DR Jack NAM Blipmap • DR Jack RASP • Skysight

  3. Acronyms • Blipmap - Boundary Layer Information Prediction MAP • RASP - Regional Atmospheric Soaring Prediction • NAM - North American Mesoscale model • NWS – National Weather Service

  4. Blipmap Advantages • My observations and recommendations are based on 15 + years experience using these tools in California, Nevada and Utah • When used and interpreted correctly, Blipmaps proved to be an excellent tool for accurately forecasting soaring conditions up to 3 days in advance • The key is to look at the most useful subset of blipmap models and parameters and interpret them correctly. One should not try to assess the soaring conditions based on a single parameter. • One size does not fit all. Some empirical tuning needed based on location and experience. • It is not as complicated as it sounds! To keep it simple I will be focusing only on the tools, models and parameters I find most useful.

  5. How accurate blipmap really is? • In 90% of the days the max altitude achieved is within 1000 feet from forecast! • It also accurately predicts the location of best lift, convergence lines, clouds and cloud bases, as well as high clouds and overcast. • In addition it accurately predicts wave location and strength. • Trend is as important as the absolute values. • It can help predicting upcoming great conditions as well as poor conditions up to 3 days in advance, resulting in much higher success ratio when using it as a planning tool to determine when and where to go flying.

  6. NAM Blipmap • Blipmap is the oldest tool (15+ years) yet still my favorite • Available up to 3 days in advance • Best for checking top of lift (BLTop), cu potential, cloudbase, wind and overcast up to 3 days in advance • Easiest map to read using “classic” color scale • More accurate for mountain terrain • Map refreshes every 6 hours • last run is the 9hrs forecast around 8AM

  7. Blipmap Parameters • BLTop – Max height of blue thermals. • Hcrit – Expected max altitude taking glider sink rate into account • Cumulus Potential – The higher the number the higher the chances for cu and the taller the cu. some locations will have cu where cu potential = 0, while other may need to have at least +2. Cu potential 5 and above indicates potential for OD.

  8. Blipmap Parameters • Cumulus Cloudbase – Cloudbase height, only meaningful in areas where cumulus potential is positive. • Composite cumulus cloudbase where potential > 0 combining both parameters but can be missleading in some areas. • Total cloud cover – A very reliable indicator for high clouds. Large white area (100%) indicates high likelihood of some level of overcast. Could be thin high clouds or total overcast.

  9. Blipmap Parameters • OD potential – Similar to cumulus potential, can indicate areas of potential OD. Not very accurate. Use cumulus potential instead. • BLMax Up/Down (convergence) – Indicates the area and strength of the convergence (50 and above indicates strong convergence). Most useful and accurate with the higher resolution RASP. • Wind speed and direction – The average wind speed and direction in the boundary layer

  10. Other Blipmap Parameters In addition to the parameters already mentioned, the following parameters may also be of interest: • Thermal Updraft Velocity (W) - It can give you an idea of the expected average climb rate but it has significantly lower resolution and is not very accurate. • B/S – Buoyancy/shear ratio. Low numbers (below 5) indicates potential choppy thermals. Usually not significant when cus are presented.

  11. RASP Blipmaps • Regional version of Dr Jack software deployed, hosted and maintained by local volunteers • Typically much higher resolution than NAM: 750m - 4km • Based on NAM/WRF model • Up to 7 days forecast, depend on deployment • Multiple times per day (if implemeted) • Can utilize a more interactive “viewer” UI • Best for predicting exact area of best lift, clouds, convergence (BL Max Up/Down) and wave

  12. RASP Blipmaps • Clouds parameters are less accurate than NAM. Cu potential is often too pessimistic while Cu base is optimistic • Color contrast usually not as good as NAM • From the above reasons I prefer to use RASP for location of lift and NAM for altitude

  13. Using Hi Res RASP for wave prediction • Check RASP wave parameters using high res models (preferably 1KM or better) • 3km resolution will show much weaker wave due to averaging • Check the vertical velocities and cross sections. • Should be over 100 cm/s (200 fpm) for a usable wave (note that color scale is not constant)

  14. Forecasting wave: Wave cross section

  15. SkySight • Most recent tool • Modern user interface • Easier to use • High Resolution • Overlaid on terrain map • Up to 7 days forecast, multiple times per day • Additional cool ambitious features • Require subscription

  16. SkySight observations • Clouds prediction more pessimistic than NAM. Often does not predict small clouds. • Convergence influence on CU are not considered at the moment • Upgrades coming soon to address these issues

  17. Tips for using blipmaps • Next day forecasts are typically available after 6:30 PM. • Saturday’s forecast is available Wednesday evening. • Compare each day to determine the trend • The longer the range the less reliable • Check date/time on top of the map to make sure it is current • Check multiple tools and models. The more consistency between the models the higher the confidence in the forecast. If there are big discrepancies, a good rule of thumb is to average their values. • Gather additional insight by discussing the forecast with others

  18. how to use these tools to maximize XC soaring results • Look for trend to determine the best days and place to fly • Determine best XC route for the day. • Look for uncommon interesting conditions for exploration • Use RASP/SkySight to determine best time to launch and when the day may end. • It is a good idea to compare actual results with the forecast using the Previous Day links, to help fine tuning the forecast to your area

  19. Links • NWS: https://www.wrh.noaa.gov/mtr/forecast.php • Blipmap: http://www.drjack.info/BLIP/index.html • Blipmap UniViewer - http://www.drjack.info/BLIP/univiewer.html • CA/NV region RASPs: https://rasp.nfshost.com/ • Hi Res RASP example - http://byron-rasp.anarian.net/home.html • SkySight: https://skysight.io/secure/

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