Friday, October 19, 2012

National Weather Service announcement: Rain early next week

10-19-12
...MAJOR CHANGE IN THE WEATHER PATTERN COMING WITH RAIN AND
MOUNTAIN SNOW FORECAST FOR EARLY NEXT WEEK...

THE FIRST MONTH OF AUTUMN HAS BEEN QUITE MILD THIS YEAR WITH MOST
OF THE DAYS OVER THE LAST MONTH SEEING DAYTIME HIGHS ABOVE SEASON
NORMALS. IF FORECAST MODELS ARE CORRECT...THIS MILD WEATHER
PATTERN IS ABOUT TO SEE A SIGNIFICANT CHANGE THANKS TO A COLD LOW
PRESSURE SYSTEM EXPECTED TO DROP OUT OF THE GULF OF ALASKA. A
SLIGHT DROP IN DAYTIME TEMPERATURES TODAY WILL BE FOLLOWED BY MORE
COOLING GOING INTO THE WEEKEND. AS THE MAIN LOW PRESSURE SYSTEM
BECOMES ESTABLISHED OFF THE COAST ON SUNDAY...CLOUDINESS AND
COOLER AIR WILL BRING DAYTIME HIGHS DOWN TO SEVERAL DEGREES BELOW
NORMAL. A FRONTAL BAND ASSOCIATED WITH THIS LOW PRESSURE SYSTEM IS
CURRENTLY FORECAST TO SWING THROUGH NORTHERN CALIFORNIA SUNDAY
NIGHT INTO MONDAY. THIS FRONTAL PASSAGE IS EXPECTED TO BRING
PRECIPITATION TO MOST OF NORTHERN CALIFORNIA.

WEATHER MODEL PROJECTIONS RANGE THE AMOUNT OF RAINFALL MONDAY INTO
TUESDAY BETWEEN ABOUT A QUARTER AND A HALF AN INCH IN THE CENTRAL
VALLEY. THIS RAINFALL WILL TRANSLATE INTO SNOWFALL OVER THE
MOUNTAINS. SNOW LEVELS WITH THIS COLD SYSTEM WILL BE FAIRLY LOW
FOR THIS TIME OF YEAR RANGING FROM ABOUT 5000 FEET OVER SHASTA
COUNTY TO AROUND 6000 FEET OVER THE NORTHERN SIERRA NEVADA. THIS
PUTS SNOWFALL DOWN TO THE MAJOR TRANS-SIERRA PASSES WHERE A FEW TO
SEVERAL INCHES OF SNOW WILL BE POSSIBLE. THIS AMOUNT OF SNOW COULD
EASILY PRODUCE TRAVEL DIFFICULTIES ESPECIALLY THIS EARLY IN THE
SEASON WHEN DRIVERS COULD BE CAUGHT OFF GUARD. THERE IS STILL SOME
UNCERTAINTY IN THE EXACT TIMING OF THIS SYSTEM BUT ALL CURRENT
INDICATIONS POINT TOWARDS NEXT WEEK STARTING OUT MUCH WETTER AND
COOLER THAN THE PREVIOUS MONTH.