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

3. 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

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

5. 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.

6. 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.

7. 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

8. 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.

9. 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.

10. 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

11. 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.

12. Comparison between cu potential prediction showing high potential for cu along the Diablo range, mendocinoes and likely OD over the Sierras, vs actual

17. Comparison between actual to total cloud cover predicting high clouds (cirrus) only over northern part of the state

18. 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

19. 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

24. 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)

26. Forecasting wave: Wave cross section26

27. 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

28. 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

31. 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

32. 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

33. Links NWS: https://www.wrh.noaa.gov/mtr/forecast.php
Blipmap:
Blipmap UniViewer -
CA/NV region RASPs:
Hi Res RASP example -
SkySight: