Squabbling International Models

No hair pulling or scratching, but the the Euro (ECMWF) and the Yank (GFS) continue to disagree about the moisture content and movement of that system expected to head down the interior west this weekend. The mets in Sacramento and the Bay Area would really like to see the two models kiss and make up (ah, wouldn't we all), but until then are betting on the Euro to prevail. Thus the lingering chance of precipitation for Sunday, mostly in the form of high-elevation snows in the Sierra, but possibly with a little rain in the valley.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1000 AM PST THU DEC 3 2009

... SEASONABLY MILD TEMPERATURES FOR FRIDAY WITH INCREASING CLOUDS IN THE AFTERNOON AHEAD OF A COLD CANADIAN SYSTEM DROPPING INTO THE PACIFIC NORTHWEST. TEMPERATURES COOL FURTHER ON SATURDAY AND SUNDAY. THE 12Z GFS SHOWS 850 MB TEMPERATURES DROPPING TO AROUND -1 TO -3 C BY SUNDAY AFTERNOON. THE EXACT POSITION OF THE LOW CONTINUES TO VARY BETWEEN MODELS AND MODEL RUNS. OVERALL BLEND OF THE MODELS SUGGEST SOME PRECIPITATION SPREADING INTO THE NORTHERN MOUNTAINS SUNDAY AFTERNOON AND THEN ACROSS THE REST OF THE AREA SUNDAY NIGHT INTO MONDAY WITH A COLD FRONT TRACKING THROUGH. SNOW LEVELS COULD BE VERY LOW WITH 700 MB TEMPERATURES DOWN TO -16 TO -18 C AND THICKNESS DOWN TO 520 TO 523 DM. THE ECMWF IS WETTER THAN THE GFS WITH THIS SYSTEM AT THIS POINT. THINKING NOW IS THAT PERHAPS A FOOT OF HIGH RATIO SNOW IS POSSIBLE OVER THE NORTHERN SIERRA WITH THIS SYSTEM. LOOKS LIKE A BREAK BETWEEN SYSTEMS ON TUESDAY...FOLLOWED BY A SYSTEM WITH A STRONG JET AND PACIFIC MOISTURE TAP FROM WEDNESDAY ON WITH SIGNIFICANT VALLEY RAIN AND MOUNTAIN SNOW LIKELY. EK