This weekend's forecast for Northern California features a "Bomb Cyclone". Here is the current forecast discussion from Sacramento:
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SACRAMENTO CA 938 AM PDT FRI MAR 18 2011 .SHORT TERM DISCUSSION... TODAY MARKS THE BEGINNING OF ANOTHER SEVERAL EXTREMELY ACTIVE WEATHER DAYS. HIGHLIGHTS INCLUDE: *FRONTAL SYSTEM MOVING THROUGH TODAY. THIS WILL BRING HEAVY MOUNTAIN SNOW, MODERATE VALLEY RAIN, LOCALLY GUSTY WINDS, AND POSSIBLY SNOW DOWN INTO THE FOOTHILLS. *MOIST CONVECTIVE REGIME TONIGHT THROUGH SATURDAY. THIS WILL BRING PERIODS OF SHOWERS AND POSSIBLY THUNDERSTORMS. *POTENTIALLY BOMBING CYCLONE OFF THE BAY AREA COAST SUNDAY. THIS COULD BRING EXTREMELY GUSTY WINDS ALONG WITH MORE RAIN AND SNOW.
The prospect of a "Bombing Cyclone" got my attention. WTF does this mean?
NOAA defines a bomb cyclone is an extratropical area of low pressure in which the central barometric pressure drops at least 24 millibars in 24 hours. Some storms have intensified as rapidly as 60 millibars in a 24 hour period. A few bomb cyclones even develop "eyes", similar to the center of a hurricane.
We don't see this too often in California. The prospect is for very high winds and convective thunderstorms, and of course LOTS of snow...FEET of snow in the mountains down to very low elevations, which means light cold powder.
Some other examples of bomb cyclones were cited on islandnet.com:
Bomb cyclones rated headlines during the1990s when several were called the "Storm of the Century" and the "Perfect Storm" by US eastern reporters. These storms generally resulted in severe blizzards forming out of Nor'easters that struck the northeastern coastal states and Canadian provinces. Many of these storms began as Colorado Lows or Gulf of Mexico lows that underwent explosive cyclogenesis, the rapid formation of an intense winter storm over a short period when they moved off the land and into the warm Gulf Stream waters off Cape Hatteras.
As a result weather bombs, or more correctly bomb cyclones, have been associated with the eastern North America coast and offshore waters, though they also form off the Asia coast in the Western Pacific and over the eastern Atlantic and Pacific Oceans. The Pacific Northwest Region of North America has seen some of its most devastating storms arise from bomb cyclogenesis.
Anyway, Sunday looks interesting, and I would guess the winds will shut down a bunch of lifts in the Sierra. With snow levels down to 2500 feet with this cold storm the powder will be outstanding if it doesn't get completely wind-hammered.
Edited by Cirquerider - 3/18/11 at 2:01pm