January 24, 2008: This site is running the code developed by Tad Hurst.

Why not submit your favorite site? I need site name, lat, long, LZ and launch altitudes and the zipcode.

- Alan



KOTX (alt)


2 DEC 2020

Temp/Wind data from:

NOAA Digital Forecast
Wed Thu Fri Sat Sun Mon
Wind Above
Wind Above
Wind Above
Wind Above
Wind Above
Wind Above
Chelan N 5 0 NE 6 0 NE 6 0 N 6 0 E 6 0 E 6 0
Jupiter Ridge NW 7 2789 SW 7 2237 W 2 2679 S 8 2237 SW 6 1897 S 8 1897
Saddle Mt N 8 1048 N 6 723 N 7 885 N 7 831 NW 6 885 N 7 831
Blanchard E 5 2786 SE 9 2786 E 3 2839 E 5 2733 SE 5 2733 SE 7 2680
BJ NE 3 4046 S 2 3036 N 5 3713 E 6 2729 E 6 2675 SE 7 2621
Fort Ebey SE 12 2931 SE 10 2825 SE 5 2878 SE 10 2825 SE 7 2825 SE 10 2825
Tiger Mt SE 22 3502 SE 8 1940 SE 8 2279 SE 7 1612 SE 5 1504 SE 6 1504

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  If a front comes through, the sounding is no longer valid.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 website.  Puddle temperatures can exceed this temperature. 

Puddle Temp: This estimate is based on the High Temp and the National Weather Service 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 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 [email protected]