Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 032208
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
308 PM PDT THU SEP 3 2015

.SYNOPSIS...NEAR TO BELOW NORMAL TEMPERATURES WILL CONTINUE
ACROSS THE REGION THROUGH THIS WEEKEND AS A LOW PRESSURE TROUGH
PERSIST ACROSS THE WEST COAST. SCATTERED SHOWERS WILL OCCUR
PRIMARILY ACROSS THE INTERIOR ON FRIDAY. A FEW ISOLATED
THUNDERSTORMS ARE POSSIBLE OVER NORTHEASTERN TRINITY COUNTY AND
POSSIBLE THE YOLLA BOLLYS FRIDAY AFTERNOON.

&&

.DISCUSSION...AN UPPER LEVEL LOW PRESSURE TROUGH PERSISTS OVER
THE NORTH WEST PACIFIC. NEAR TO BELOW NORMAL TEMPERATURES WILL
CONTINUE ACROSS THE REGION THROUGH THIS WEEKEND. AN UPPER LEVEL
LOW PRESSURE TROUGH WILL MOVE ACROSS THE REGION FRIDAY. THE LOW
PRESSURE TROUGH WILL PRODUCE A SLIGHT CHANCE FOR SHOWERS PRIMARILY
ACROSS THE NORTHERN AND INLAND AREAS FRIDAY AFTERNOON AND FRIDAY
NIGHT. A FEW ISOLATED THUNDERSTORMS ARE POSSIBLE PRIMARILY ACROSS
NORTHEASTERN TRINITY COUNTY AND POSSIBLY THE YOLLA BOLLYS LATE
FRIDAY AFTERNOON. DRIER CONDITIONS AND WARMER TEMPERATURES WILL
PREVAIL OVER THE INTERIOR NEXT WEEK AS A HIGH PRESSURE RIDGE
BUILDS ACROSS THE REGION.

&&

.AVIATION...VFR WILL PREVAIL ACROSS NORTHERN CALIFORNIA THROUGH THE
REMAINDER OF THE DAY. EXPECT SOME CLOUDS TO DEVELOP ACROSS INTERIOR
VALLEYS ONCE AGAIN TONIGHT WITH SOME PATCHY MVFR CEILINGS DEVELOPING
NEAR HUMBOLDT BAY LATE TONIGHT. VFR CONDITIONS WILL OTHERWISE
PERSIST FOR ALL OTHER AREAS.

&&

.MARINE...FRESH TO STRONG NORTHERLY WINDS WILL PERSIST OVER THE NEXT
FEW DAYS AS SURFACE HIGH PRESSURE OFFSHORE PINCHES THE PRESSURE
GRADIENT AGAINST THE COASTAL THERMAL TROUGH. WINDS ACROSS THE
NORTHERN WATERS WILL DECREASE BRIEFLY EARLY FRIDAY AS A PASSING
SHORTWAVE WEAKENS THE PRESSURE GRADIENT THUS THE ADVISORIES ACROSS
THE NORTHERN WATERS AND SOUTHERN INNER WATERS SHOULD BE GOOD TO
EXPIRE FRIDAY MORNING. HOWEVER, ONCE THE TROUGH SHIFTS EAST RIDGING
WILL STRENGTHEN THE PRESSURE GRADIENT FRIDAY NIGHT THROUGH SATURDAY.
AN ADVISORY, AT LEAST FOR THE NORTHERN OUTER WATERS, MAY BE NEEDED
FOR INCREASING WINDS SATURDAY AND SUNDAY. CONFIDENCE IS LOW WHETHER
THESE WINDS WILL REACH THE INNER WATERS SO WILL WAIT TO ISSUE TIL
FRIDAY. WIDESPREAD WINDS SHOULD FALL BELOW ADVISORY CRITERIA LEVELS
BY THE MIDDLE OF NEXT WEEK AS THE RIDGE OFFSHORE WEAKENS AND SHIFTS
NORTHWARD ALLOWING THE GRADIENT TO RELAX.

SHORT PERIOD WAVE ENERGY IS INCREASING DOMINANCE ON THE WAVE
SPECTRUM DUE TO THE INCREASING WINDS. BUOY OBSERVATIONS SHOWED THAT
THESE WAVES EXISTED ALONGSIDE WITH A MID PERIOD SWELL SYSTEM EARLY
THIS AFTERNOON. THE SHORTER PERIOD WAVES WILL DIMINISH SLIGHTLY ON
FRIDAY IN RESPONSE TO THE WINDS AND BUILD AGAIN BY SUNDAY. MULTIPLE
SOUTHERLY LONG PERIOD WAVE SYSTEMS WILL PROPAGATE THE COASTAL WATERS
THROUGH EARLY NEXT WEEK. THE FIRST OF THE SYSTEMS TO BUILD NEAR 2 FT
AROUND 17 SECONDS ON SUNDAY AND THE SECOND TO BUILD NEAR 3 FT AROUND
17 SECONDS BY TUESDAY. LITTLE IMPACTS ARE EXPECTED FOR MARINERS IN
DEEP WATER, HOWEVER, INDIVIDUALS NEARSHORE OR IN THE SURF ZONE COULD
SEE STRONGER CURRENTS ESPECIALLY SOUTH OF CAPE MENDOCINO. KML


&&

.FIRE WEATHER...GOOD OVERNIGHT RH RECOVERIES WILL CONTINUE
THROUGH THIS WEEKEND. DRIER AIR AND WARMER TEMPERATURES WILL
PREVAIL ACROSS THE REGION EARLY NEXT WEEK AS A WEAK OFFSHORE FLOW
DEVELOPS. AN UPPER LEVEL TROUGH AND NEARLY CUT OFF LOW MAY
INCREASE INSTABILITY ENOUGH FOR A FEW ISOLATED THUNDERSTORMS
FRIDAY AFTERNOON AND EARLY EVENING PRIMARILY OVER NORTHEASTERN
TRINITY COUNTY AND POSSIBLY THE YOLLA BOLLYS. QPF VALUES ARE
EXPECTED TO BE FAIRLY LIGHT WITH VERY LOCALIZED HIGHER AMOUNTS
BENEATH ANY THUNDERSTORMS.


&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 9 AM PDT FRIDAY FOR PZZ450.

     SMALL CRAFT ADVISORY UNTIL 9 AM PDT FRIDAY FOR PZZ470.

     SMALL CRAFT ADVISORY UNTIL 9 AM PDT FRIDAY FOR PZZ455.

     SMALL CRAFT ADVISORY UNTIL 3 AM PDT MONDAY FOR PZZ475.

&&

$$

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