Storm Watch, 12/15/10

Oh, boy … look at this morning’s discussion from NOAA out of Monterey. I’ve highlighted a few things, and pared it down a bit, but this storm system is still shaping up as expected.

“THINGS SHOULD START TO GET MORE INTERESTING LATER FRIDAY NIGHT INTO EARLY SATURDAY WHEN A NARROW PLUME OF 1.5 TPW TAKES AIM AT THE BAY AREA. CURRENT SOLUTIONS SHOW THIS BOUNDARY SETTING UP FROM THE SANTA CRUZ MOUNTAINS SOUTHWARD ALONG THE BIG SUR COAST …
SATURDAY WILL BE THE FIRST ROUND OF HEAVY RAIN ACROSS THE DISTRICT ESPECIALLY FOR THE COASTAL HILLS …

THERE WILL LIKELY BE A LULL IN THE ACTION SOMETIME SATURDAY BUT THE MAIN HOSE MAY REMAIN FAIRLY STATIONARY FOR A LONG PERIOD OF TIME ON THE SOUTHERN EDGE OF THE SYNOPTIC SCALE TROUGH. CURRENT MODEL SOLUTIONS KEEP THE HEAVIEST RAIN IN THE SOUTHERN HILLS OVER THE
WEEKEND AND THEN SHIFT THE BOUNDARY NORTH OF THE GOLDEN GATE FOR NEXT WEEKS SYSTEMS…WHICH WOULD BE GOOD NEWS…SO AS TO NOT FOCUS ALL OF THE EXTREMELY HEAVY RAIN OVER A SMALL AREA. GFS AND ECMWF MODELS STILL SHOW WIDESPREAD 5-10 INCH RAINFALL POTENTIAL FROM FRIDAY THROUGH CHRISTMAS EVE ACROSS OUR HILLS WITH GENEROUS 2-5 INCH TOTALS FOR THE VALLEYS. MANY OF THESE NUMBERS MAY STILL BE UNDERSTATED AND NO DOUBT SOME OF OUR USUAL WET SPOTS (VENADO/BEN LOMOND AND VARIOUS SPOTS IN THE SANTA LUCIAS) COULD SEE SOME 7 DAY RAIN TOTALS BEYOND 15 INCHES. NEEDLESS TO SAY HYDRO ISSUES WILL BE FRONT AND CENTER WITH URBAN AND SMALL STREAM NUISANCE FLOODING BECOMING LIKELY OVER THE WEEKEND AND INTO NEXT WEEK. SIGNIFICANT RISES ON THE MAIN STEM RIVERS IS TO BE EXPECTED AS WELL BUT OF COURSE CURRENT RIVER LEVELS ARE QUITE LOW HEADING INTO THIS EVENT.”

My SLO Co. meteorologist has been much more conservative all week, until today. He said:
“The first system will produce increasing clouds and southerly winds early Friday leading to rain and strong to gale force (25 and 38 mph) southeasterly winds with guest reaching 45 mph on Friday afternoon through Sunday morning. The heaviest rain will occur on Saturday. The winds will decrease to fresh to strong (19 and 31 mph) levels and shift out of the southwest on Saturday.

The rain and southerly winds will temporarily taper off later on Sunday into Monday. Rainfall amounts over the weekend should range between 0.75 and 1.5 inches in the North County, 1 and 3 inches in the coastal valleys of San Luis Obispo county with higher amounts in the coastal mountains.

The next low pressure system will produce increasing southerly winds and moderate to heavy rain Monday evening into Wednesday morning. Rain will likely be very heavy on Tuesday, especially over the higher terrain. At this time, the main focus for the precipitation will likely be north of Big Sur where 3 to 5 inches of rain may fall over a two day period leading to possible hydrological problems. However, the last two model runs have put more of the moisture over the Central Coast.

The last in this series of storms is forecast to produce rain and southerly winds over the Central Coast next Thursday into Friday. Fair weather should return on Christmas.”