Small Craft Advisory for Winds 57, NWS Eureka, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
254 PM PDT WED SEP 16 2009

.SYNOPSIS...A WEAK TROUGH OF LOW PRESSURE WILL REMAIN OVER
NORTHERN CALIFORNIA THROUGH SATURDAY BUT DRY AND SLOWLY
MODERATING TEMPERATURES CAN BE EXPECTED. BY LATE IN THE WEEKEND
AND EARLY NEXT WEEK...A STRONG RIDGE OF HIGH PRESSURE WILL
DEVELOP OVER THE WESTERN STATES AND POTENTIALLY RESULT IN
UNSEASONABLY WARM TEMPERATURES.

&&

.DISCUSSION...LATEST SATELLITE IMAGERY SHOWS THAT A WEAK FRONT HAS
ESSENTIALLY DISINTEGRATED ACROSS THE NORTHERN CALIFORNIA WITH THE
BULK OF THE ENERGY AND UPPER LEVEL SUPPORT REMAINING TO THE NORTH.
HIGH AND MID LEVEL CLOUDS ARE DECREASING AS THEY ATTEMPT TO WORK
INLAND WHILE SOME LOW CLOUDS ARE DEVELOPING ALONG THE IMMEDIATE
COAST...ESPECIALLY IN THE VICINITY OF CRESCENT CITY...AS WINDS AT
LEAST TEMPORARILY TURN ONSHORE. THE MARINE LAYER DEPTH AND
PRESSURE GRADIENTS SUGGEST THAT LOW CLOUD AND STRATUS DEVELOPMENT
SHOULD BE FAIRLY LIMITED THIS EVENING AND THEN BECOME JUST A BIT
MORE WIDESPREAD DURING THE LATE NIGHT HOURS.

AN UPPER LEVEL TROUGH WILL REMAIN SITUATED OVER THE NORTHWEST
U.S. ON THURSDAY AND FRIDAY...WITH ANOTHER WEAK FRONT PASSING
JUST TO OUR NORTH FRIDAY NIGHT INTO EARLY SATURDAY. WHILE MID
LEVEL HEIGHTS DO FALL SOME WITH THIS FEATURE...THEY DO NOT APPEAR
LOW ENOUGH TO WARRANT PRECIPITATION OVER OUR AREA. WE MAINTAINED
ONLY SILENT POPS FOR THIS PERIOD.

IN WAKE OF THIS SYSTEM...STRONG HIGH PRESSURE WILL BEGIN TO
DEVELOP OVER THE WESTERN STATES WITH A THERMAL LOW FORMING OVER
INTERIOR CALIFORNIA. THE ECMWF AND GFS ENSEMBLE MEAN SHOW HEIGHTS
BETWEEN 590 AND 600 DM BY MONDAY...WITH H85 TEMPERATURES NEAR 24C
IN THE INTERIOR LOCATIONS. IF THESE MODEL SOLUTION VERIFY...WE
WILL HAVE NEAR RECORD HIGHS ACROSS MUCH OF OUR AREA. THERE ALSO
SEEMS TO BE SOME SUPPORT FOR INCREASING WIND SPEEDS OVER THE
RIDGES...SO FIRE WEATHER WILL BECOME A CONCERN.  BETTWY

&&

.MARINE...A WEAK RIDGE BUILDING OVER THE AREA WILL INDUCE A WEAK
THERMAL TROUGH ALONG THE COAST OF NRN CAL TONIGHT. THIS WILL CAUSE
THE PRES GRAD TO TIGHTEN YIELDING INCREASING WINDS AND SEAS...WHICH
WARRANT A SCA FOR THE INNER WATERS INTO THU EVENING AND THE OUTER
WATERS INTO SUN AFTERNOON. SEE ADVISORIES BELOW. A WEAKENING FRONT
WILL CROSS THE REGION ON SAT ALLOWING FOR THE PRES GRAD TO EASE IN
THE OUTER WATERS...BRINGING THE WINDS AND SEAS DOWN BY SUN. HIGH
PRES W OF THE WATERS AND A WEAK PATTERN E OF THE AREA WILL ALLOW FOR
DIMINISHED WINDS AND SEAS THROUGH MON. IF MODELS SHIFT THE RIDGE A
BIT FURTHER TO THE E SUN INTO MON...SCA CONDITIONS MAY BE WARRANTED
AGAIN.   BFG

&&

.AVIATION...AS A COLD FRONT PUSHES INTO AND THROUGH THE
AREA...COASTAL LOCATIONS CAN EXPECT OCCASIONALLY GUSTY WINDS.
AMPLE MOISTURE WILL BE BROUGHT INTO THE REGION AS WELL...SO AS
THE TEMPERATURE COOLS DOWN INTO THE EVENING HOURS...LOW CLOUDS
AND WILL BE PREVALENT AND GROUND CONDITIONS WILL BE MISTY. THE
ADDED LIFT IN THE REGION OF THE FRONT SHOULD PROHIBIT GROUND
VISIBILITIES FROM FALLING TO ANYTHING LESS THAN 2 MILES...THOUGH
LOW CLOUDS WILL BE QUITE DENSE BETWEEN 200 AND 400 FT. INLAND
LOCATIONS CAN EXPECT CLEAR SKIES THROUGHOUT THE PERIOD...AND
TERRAIN-DRIVEN GUSTY WINDS IN THE AFTERNOON.   MSB

&&

.EKA WATCHES/WARNINGS/ADVISORIES...

SMALL CRAFT ADVISORY FOR WINDS FROM 8 AM TO 9 PM PDT THURSDAY FOR
PZZ450-455.

SMALL CRAFT ADVISORY FROM 5 AM THURSDAY TO 2 PM PDT SUNDAY FOR
PZZ470-475.

&&

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