Owens Valley is called "the land of little rain" because of a "rain shadow" effect caused by the westerlies crossing the Sierra.
At 14,000 feet and higher, winds are often true out of the west or southwest, while below, they funnel up and down the Valley.
Local katabatic flows begin in the evening and carry on through the night as heavier, cooler air drains out of the Great Basin
southward into the Upper Mojave Desert.
In the morning, solar heating causes the Mojave air to warm and expand.
The north winds will typically switch around 9:30 or 10:00 a.m. in the summer.
When this happens, the shadowed pockets of warm air on the Sierra foothills are
disturbed and break free, presenting an opportunity for bolder pilots to launch early on cross country attempts.
This is what Tudor and Kohmstedt did in 1983.
The trick is to gain as much altitude as possible up Wanoga Peak above Horseshoe, then head north, working
everything because after the initial thermal surge, conditions will weaken as thermals build again in new pockets sheltered from the south wind.
The best opportunity for finding lift is close to sun-facing vertical walls.
That's the local part.
Many pilots have been suckered into planning for the local part without taking into account the potential rising wind factor driven
by global pressure events such as the current one.
Horseshoe is particularly sheltered by the prominent south ridge.
You can set up on Horseshoe in calm or light north conditions, awaiting the wind direction change,
and launch into a suddenly rising south valley wind that only makes itself apparent when you reach the mouth of the canyon.
This can expose you to strong turbulence, strong sink and a high-wind landing on the alluvial fan.
At launch, I would always ask arriving pilots about the wind conditions at the "Postage Stamp" LZ.
In the morning, 9:00 to 11:00, conditions should be light, 0 to 5 mph. Ten mph might indicate trouble coming.
A wonderful thing about flying the Owens is the dryness.
When trouble is coming, it's like the polite rattlesnake.
Yes, it can hurt you but it tells you it's there first.
Rising wind is indicated by haze or clearly rising dust to the south.
There is always time to land safely. One can even run north to buy time it.
One must only be vigilant and continue to check to the south periodically.
A danger develops when the ground is moist and does not allow the growing wind to raise dust.
So when one arrives in Owens Valley, check the quality of the soil in several locations as you drive north.
I have been caught in suddenly-rising wind conditions while flying after rain has dampened the soil.
There is often no way to tell how severe the wind is going to become but there are indications.
Lift disappears.
Turbulence grows.
Your drift increases.
By the time you near the ground, you may not be able to penetrate.
My worst experience was on a XC attempt from Horseshoe when I suddenly encountered a strong north wind at the north face of the Poverty Hills.
I was blown backwards to a landing near Hy 395 where the fields are crossed with power lines.
Having nature choose your landing spot is not good.
Looking back over my shoulder, I saw I was going to collide with a power line.
I had the bar stuffed in turbulence so I eased out and coasted 20 feet over the set of power lines,
then I dove and landed the glider in the lesser wind at ground level before the next set of power lines.
The lesser wind is almost always there - it is a relief to see your backwards drift become a hover when you touch down -
so expect it and dive forward to grab your nose wires when you touch down.
Faster, smaller glidersmake this less risky. I was flying a big 190 Moyes double-surface.
There may be lenticulars later today and tomorrow..
Wind Advisory
URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE LAS VEGAS NV
225 AM PDT THU APR 14 2016
AZZ001>003-036-CAZ519>522-526-527-NVZ014>022-142300-
/O.CON.KVEF.WI.Y.0016.160415T0700Z-160417T0000Z/
NORTHWEST PLATEAU-LAKE HAVASU AND FORT MOHAVE-NORTHWEST DESERTS-
LAKE MEAD NATIONAL RECREATION AREA-EASTERN SIERRA SLOPES-
OWENS VALLEY-WHITE MOUNTAINS OF INYO COUNTY-
DEATH VALLEY NATIONAL PARK-CADIZ BASIN-SAN BERNARDINO COUNTY-
UPPER COLORADO RIVER VALLEY-ESMERALDA AND CENTRAL NYE COUNTY-
LINCOLN COUNTY-NORTHEAST CLARK COUNTY-
WESTERN CLARK AND SOUTHERN NYE COUNTY-SHEEP RANGE-
SPRING MOUNTAINS-RED ROCK CANYON-LAS VEGAS VALLEY-
SOUTHERN CLARK COUNTY-
INCLUDING THE CITIES OF...COLORADO CITY...
PIPE SPRING NATIONAL MONUMENT...TUWEEP...MT TRUMBELL...
WESTERN GRAND CANYON...LAKE HAVASU CITY...DESERT HILLS...TOPOCK...
KINGMAN...GOLDEN VALLEY...DOLAN SPRINGS...VALENTINE...WIKIEUP...
YUCCA...BULLHEAD CITY...OATMAN...MOHAVE VALLEY...ASPENDELL...
MT WHITNEY...BISHOP...INDEPENDENCE...LONE PINE...OLANCHA...
WESTGARD PASS...BRISTLECONE PINE...FURNACE CREEK...
STOVEPIPE WELLS...SHOSHONE...VIDAL JUNCTION...NEEDLES...BEATTY...
GOLDFIELD...SILVER PEAK...DYER...CALIENTE...PIOCHE...PANACA...
HIKO...ALAMO...RACHEL...MESQUITE...OVERTON...MOAPA...PAHRUMP...
INDIAN SPRINGS...DESERT ROCK...AMARGOSA VALLEY...
THE TOWN OF MT CHARLESTON...RED ROCK CANYON...LAS VEGAS...
NORTH LAS VEGAS...HENDERSON...BOULDER CITY...HOOVER DAM...
LAUGHLIN...PRIMM....SEARCHLIGHT...CAL-NEV-ARI
225 AM PDT THU APR 14 2016 /225 AM MST THU APR 14 2016/
...WIND ADVISORY REMAINS IN EFFECT FROM MIDNIGHT PDT /MIDNIGHT
MST/ TONIGHT TO 5 PM PDT /5 PM MST/ SATURDAY...
* TIMING... WINDS ARE EXPECTED TO INCREASE EARLY FRIDAY
MORNING...PEAK FRIDAY AFTERNOON...THEN GRADUALLY DECREASE
THROUGH SATURDAY.
* WINDS...NORTH 25 TO 35 MPH...GUSTS 35 TO 50 MPH.
* IMPACTS...DIFFICULT TRAVEL CONDITIONS DUE TO STRONG...GUSTY
CROSSWINDS. TEMPORARY FENCES AND STRUCTURES MAY BE DAMAGED OR
DISPLACED. LIMITED AREAS OF BLOWING DUST IS POSSIBLE IN AREAS
WHICH RECEIVED LITTLE TO NO PRECIPITATION IN THE LAST WEEK.
STRONG WINDS IN EXCESS OF 30 MPH WILL CREATE DANGEROUS BOATING
CONDITIONS ON AREA LAKES DURING THE ADVISORY PERIOD. THESE
WINDS WILL CREATE VERY CHOPPY WATERS AND GENERATE LARGE WAVES
WHICH COULD CAPSIZE OR SWAMP SMALL CRAFT.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A WIND ADVISORY MEANS THAT CROSSWINDS ARE EXPECTED TO BE STRONG
ENOUGH TO MAKE DRIVING DIFFICULT...ESPECIALLY FOR HIGH PROFILE
VEHICLES. IN ADDITION...STRONG WINDS OVER DESERT AREAS COULD
RESULT IN BRIEFLY LOWERED VISIBILITIES TO WELL UNDER A MILE AT
TIMES IN BLOWING DUST OR BLOWING SAND. USE EXTRA CAUTION.
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