‘Significant Precipitation’

Raw discussion from the Weather Service in Eureka:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
325 AM PST THU MAR 10 2011

.SYNOPSIS…AN APPROACHING FRONTAL SYSTEM WILL BRING GUSTY WINDS AND
WIDESPREAD RAINFALL TO NORTHWEST CALIFORNIA TODAY. ADDITIONAL STORMS
WILL AFFECT THE AREA SATURDAY AND SUNDAY AS THE ACTIVE WEATHER PATTERN
CONTINUES.

&&

.DISCUSSION…MAIN FCST CONCERNS THIS MORNING ARE RAINFALL TOTALS
FOR TODAY…THEN TIMING OF FRONTAL SYSTEMS SAT AND SUN.

AMSU TPW IMAGE EARLY THIS MORNING SHOWS A 1.0 INCH SWATH
EXTENDING FROM NORTH OF HAWAII ALONG A COLD FRONT THAT IS
CURRENTLY 150 MILES WEST OF EUREKA. WITH THIS GOOD MOISTURE TAP
AND FAIRLY GOOD DYNAMICS THIS STORM HAS THE POTENTIAL TO DELIVER A
SIGNIFICANT PRECIPITATION EVENT FOR PARTS OF THE AREA. RADAR
RETURNS ARE VERY IMPRESSIVE OVER DEL NORTE COUNTY WHERE 1.5 TO 2.5
INCHES OF RAIN IS EXPECTED. DOWNSLOPE FLOW OFF THE KING RANGE WAS
LIMITING QPF VERY EARLY ON AROUND HUMBOLDT BAY…BUT THE FLOW HAS
SHIFTED MORE TO THE SW ALLOWING MODERATE RAIN TO FILL IN AROUND
THE EUREKA AREA. THE SPEED AT WHICH THE FRONT MOVES INLAND HAS
BEEN VERY CONSISTENT..WITH MOST OF THE PRECIP WINDING DOWN BY
MID/LATE AFTERNOON. BASED ON CURRENT TRENDS…I SEE NO REASON TO
DISCOUNT THE MODELS AND DEVIATE MUCH FROM THE PREVIOUS FCST. AREA
RIVERS SHOULD RESPOND QUICKLY TO THE RAIN TODAY…BUT CURRENT
FCSTS KEEP LEVELS BELOW ANY ACTION STAGES.

SNOW LEVELS WILL BEGIN FAIRLY HIGH WITH SNOW ABOVE 5500-6000 FT THIS
MORNING…BUT DROPPING QUICKLY TO 3000 FT BEHIND THE FRONT
TONIGHT. BY THE TIME THE COLDEST AIR ARRIVES… RESIDUAL QPF WILL
BE VERY LIGHT…LESS THAN 0.10 INCHES…SO THAT SNOWFALL HIGHLIGHTS
ARE NOT EXPECTED AS IMPACTS LOOK MINIMAL FOR LOCAL TRANSPORTATION.

A VERY BRIEF PERIOD OF FLAT RIDGING WILL AFFECT THE AREA LATE
TONIGHT INTO FRIDAY MORNING BEFORE SOUTH FLOW SETS UP ACROSS THE REGION
AHEAD OF THE NEXT STORM SYSTEM. THE FIRST LOW OF THE WEEKEND WILL
SPREAD RAIN INTO THE CWA DURING THE DAY SATURDAY…WITH
PRECIPITATION TOTALS GENERALLY UNDER 0.50 INCH. A STRONGER SYSTEM
IS FORECAST TO AFFECT THE AREA ON SUNDAY. THE MOISTURE SOURCE FROM
THIS SYSTEM MAY ALSO HAVE TROPICAL ORIGINS…SO QPF TOTALS HAVE
BEEN INCREASED…WITH SEVERAL INCHES NOT OUT OF THE QUESTION. THE
ACTIVE PATTERN LOOKS TO EXTEND INTO NEXT WEEK UNDER CONTINUED
ZONAL FLOW. JCA/SMITH

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