The level of confidence this will be a major storm is high. This compares to other predictions which ended up with big storms weakening before landfall.

Model after model, run after run, there is agreement on all the ingredients coming together to make this not just messy, but relatively damaging to property.

I've not heard 'storm of the decade' used, but meteorologists are comparing alongside notable storms of years past that have been destructive. As such, recommendations to protect life and property have been issued.

Delays of mainline and cancellations of baby birds come with any decent storm to the Bay Area. All forecast guidance suggests this storm will be of a larger magnitude. Travelers to/from/thru the Bay Area Thursday/Friday really should think through those plans and have backup plans (and backup travel kit - if stranded) in order.

Assuming UA meteorologists use more than The Weather Channel and the Old Farmers Almanac to base their decisions, I'd be surprised if a WW isn't issued by nightfall Wednesday.

An excerpt from the NWS/NOAA weather discussion this morning - specific to Aviation: (emphasis mine)

http://forecast.weather.gov/product....n=1&glossary=1

AVIATION...AS OF 4:00 AM PST WEDNESDAY...PATCHY FOG AND LIFR-IFR
CLOUD DECKS HAVE PERSISTED THROUGH THE NIGHT AS A RESULT OF LIGHT
WINDS AND A MOIST NEAR SURFACE ENVIRONMENT. CIGS SHOULD SHOW MINOR
SIGNS OF IMPROVEMENT BTWN 17-18Z WED HOWEVER MVFR TO IFR CIGS WILL
PREVAIL THROUGH THE DAY AHEAD OF AN APPROACHING PACIFIC POWERHOUSE
OF A STORM.

A COPIOUS RAINFALL PATTERN IS SETTING UP OVER THE BAY AREA AND NORTH
CENTRAL COAST FOR LATE WEDNESDAY NIGHT THROUGH THURSDAY EVENING. AS
ADVERTISED IN THE PUBLIC FORECASTS EXPECT HEAVY RAIN AND HEAVY WIND
TO MOVE INTO THE REGION STARTING LATE TOMORROW NIGHT AND CONTINUE
THROUGH THURSDAY. THE 12Z TAFS INCLUDE THE VANGUARD OF THE EXPECTED
IMPACTS FROM HEAVY RAIN AND GUSTY SOUTHERLY WINDS. WANTED TO
MENTION THIS BECAUSE THERE`LL VERY LIKELY BE NUMEROUS FLIGHT
DELAYS AND CANCELLATIONS IN AND OUT OF THE BAY AREA FOR MID TO
LATE WEEK. A RAPIDLY DEEPENING EASTERN PACIFIC SURFACE LOW
PRESSURE AREA WILL RACE NORTHEAST REACHING SW OREGON THURSDAY
MORNING. A TRAILING COLD FRONT WILL BE MOVING OVER ANOMALOUSLY
WARM DECEMBER CA COASTAL WATER TEMPS OF WHICH ARE UNPRECEDENTED
FOR ANY DECEMBER AT LEAST BACK THROUGH THE 1980S PER RECENT CHECK
OF NATIONAL DATA BUOY CENTER (NDBC) DATA. RESULTANT INSTABILITY IS
QUITE LIKELY TO RAMP UP THE PROBABILITY OF T-STORMS/RAINFALL
RATES.

VICINITY OF KSFO...MVFR TO IFR CIGS THROUGH WEDNESDAY MORNING.
GUSTY SOUTH-SOUTHEAST WINDS PICK UP BEGINNING AT 04Z THU. WINDS
AND RAIN WILL BEGIN TO PEAK AT OR AROUND 15Z THU AND CONTINUE FOR
THE THURSDAY MORNING PUSH. +RA/TS AND SUSTAINED WINDS OVER 30KTS
AND GUSTS OVER 45KTS ARE ALL POSSIBLE THURSDAY MORNING.