Feb 16, 2021
- Problems getting data from National Weather Service began on Feb 11 impacting operation of the Soaring Predictor software.
The service seems to be working again at about 75% as of this morning, Feb 16.

Backup data is being sourced from however, their free service is limited to 3 days. If you see a three day forecast for your favorite site, thank the WeatherAPI folks. The full 5-day forecasts are receiving input data from the National Weather service (thank them too :-).



KOAK (alt)


16 APR 2021

Temp/Wind data from:

NOAA Digital Forecast
Fri Sat Sun Mon Tue Wed
Wind Above
Wind Above
Wind Above
Wind Above
Wind Above
Wind Above
Dumps W 13 279 W 11 279 WNW 11 1598
Mt Diablo WSW 10 11335 N 11 13366 W 9 14333
Ed Levin WNW 8 6548 WNW 10 9231 WNW 8 11520
Mission Peak WNW 8 6053 WNW 10 8336 WNW 8 10114
Potato Hill NE 10 9927 NNE 12 10924 NE 7 12787
Mt Tamalpais W 11 3353 WNW 11 4869 WNW 10 6265
Tollhouse WSW 7 6388 SW 7 7003 WSW 7 8460
Elk Mountain W 10 11507 W 10 12295 W 8 13272
Big Sur NW 8 3533 NW 10 4984 W 5 6457
Ft Funston W 14 0 W 11 0 W 11 1414
Marina Beach WNW 9 0 NW 8 0 NW 7 1547
Dunlap W 6 7317 SW 5 7860 W 6 11431
Weaver Bally E 5 20259 ENE 6 20259 W 5 21689
Timberline WSW 8 14214 WSW 7 14976 WSW 7 15917
Burn Launch NE 7 6040 ENE 10 7193 NNE 2 13359
Hat Creek Rim NNE 10 6849 ENE 8 7617 SW 6 12377
St John NE 10 16028 NNE 12 16401 NE 7 17333
Noel Springs NNE 9 14704 NNE 11 14893 NNE 7 15833
Lake McClure WNW 10 6253 SW 5 6312 W 8 9049
Sugar Hill NE 15 7518 ENE 7 11353 WNW 4 15315
Goat Mountain NW 9 10368 N 11 12111 NW 6 15194
Mt Vaca SW 11 14514 N 13 15923 NNE 8 17598

DISCLAIMER: These estimates are intended to assist in daily site selection only.  No warranty is made concerning the accuracy of these estimates.  These estimates cannot be used to determine if conditions are safe for flying.  Conditions should be evaluated at the launch site by experienced pilots before launching.

Sounding: This is the site at which the weather balloon was released.  If the flying site predicted is far from the sounding site, the estimate is not valid.  Also, the sounding is done at 12Z (4AM PST).  If a front comes through, the sounding is no longer valid. The sounding becomes less valid later in the day.

Thermal Ceiling: the lower of the height at which the thermal stops rising and the cloud level.  We can't fly into the clouds, so it doesn't matter how much higher the thermal goes.  Remember that we can't get to the top of the thermal because of our sink rate.  Our upper limit will be lower than the reported ceiling.

Soaring Ceiling: We will stop going up when the thermal is rising just fast enough to offset our sink.  It is estimated that this happens when the temperature difference between the thermal and the surrounding air is about 2 degrees F. This number is an estimate of the maximum altitude we might reach if we start at launch height, and should be more reflective of our chances of soaring than the thermal top. Please let me know how this compares with actually flying, and I will adjust it as necessary.

Above Launch: The difference between how high we might get and how high we start. This estimate does not account for ridge lift.

High Temp: This estimate is taken from the National Weather Service or website.  Puddle temperatures can exceed this temperature. 

Puddle Temp: This estimate is based on the High Temp and the National Weather Service or estimate of cloudiness, and the angle of the sun.  When the sun is directly overhead on a sunny day, the puddle temp is esimated to be 25 degrees warmer than the high ambient temperature. This estimate now includes a rigorous calculation of the Sun Angle, and accounts for the seasonal differences in zenith and daylight hours.

Wind: This estimate is taken from the National Weather Service or website.

Wind Gust: This estimate is taken from the National Weather Service or website.

Thermal Type: Blue (no cloud formation) or White (Cloud formation)

Thermal Index: This is the maximum difference in temperature between the rising packet of air (the thermal) and the surrounding air.  The difference in temperature is responsible for the buoyancy of the thermal, and larger temperature differences mean faster rising thermals.  A value of about 10 F or greater often means that the conditions are soarable.  Values above 20 could indicate rowdy thermals.

Validity of estimate: Many factors (including strong wind, fronts, cloud shadows, incorrectly predicted temperatures, etc) can affect the validity of the estimates. 

Author: Tad Hurst

Supported By: Alan Crouse