Check weather.gov for Las Vegas, NV, and position the moving map to Mt. Whitney. You may need to zoom in one or two levels to see Whitney. Click it for a Whitney forecast. Then, in the lower right hand area, look for "Forecast Discussion" and click it. There is some weather jargon, but it is generally understandable. A southwest flow is dry and there will be no thunderstorms. A southeast flow brings moisture and the possibility of thunderstorms. Here is the current discussion:
.SYNOPSIS...
SOUTHWESTERLY FLOW ALOFT WILL KEEP SKIES CLEAR AND DRY ACROSS THE REGION THROUGH SATURDAY. OVER THE WEEKEND SOME MOISTURE WILL MOVE INTO THE REGION FROM THE SOUTHEAST FOR AN INCREASE IN CLOUDS. EARLY NEXT WEEK A TROUGH OF LOW PRESSURE WILL MOVE ACROSS THE REGION BRINGING COOLER AIR.
Remember that the mountains make their own weather and anything is possible at any time. Dress in layers and be prepared for the worst.
