SFOAFDEKA (05/14/13 0418)
FXUS66 KEKA 141122
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
422 AM PDT TUE MAY 14 2013
.SYNOPSIS...HIGH PRESSURE OVER THE REGION WILL CONTINUE MOSTLY
DRY CONDITIONS TODAY INTO WEDNESDAY. ANOTHER TROUGH WILL APPROACH
LATE WEDNESDAY...BRINGING A CHANCE OF RAIN TO THE REGION ON
THURSDAY. A FEW SHOWERS WILL LINGER ON FRIDAY AS HIGH PRESSURE
SLOWLY REBUILDS.
&&
.SHORT TERM....TODAY THROUGH THURSDAY.
HIGH PRESSURE WILL DOMINATE THE WEATHER TODAY WITH DRY CONDITIONS
AND MOSTLY CLEAR SKIES. COASTAL STRATUS WILL QUICKLY DIMINISH
THROUGH THE MORNING HOURS AS NORTHWESTERLY WINDS INCREASE WITH
HIGH PRESSURE BUILDING OVER THE EASTERN PACIFIC. 850 MB
TEMPERATURES ARE EXPECTED TO BE VERY SIMILAR TO MONDAY WHICH
SHOULD ALLOW FOR MOST LOCATIONS TO REACH TEMPERATURES MUCH LIKE
YESTERDAY. COASTAL AREAS MAY BE A FEW DEGREES COOLER THAN
YESTERDAY WITH THE INCREASED WINDS OFF THE COLDER COASTAL WATERS.
A DEEPENING TROUGH OFF THE COAST WILL BEGIN TO MOVE INTO THE PACIFIC
NORTHWEST TONIGHT BRINGING WITH IT INCREASED HIGH CLOUDS TO
NORTHWEST CALIFORNIA AND WEAKENING COASTAL WINDS. STRATUS MAY
REDEVELOP ALONG THE COAST AS BOUNDARY LAYER MOISTURE INCREASES
AHEAD OF THE TROUGH TUESDAY NIGHT INTO WEDNESDAY MORNING. LOW
CLOUDS MAY CLEAR OUT DURING THE DAY WEDNESDAY ALONG THE
COAST...BUT HIGH AND MID CLOUDS WILL BE ON THE INCREASE THUS THE
FORECAST IS FOR MOSTLY CLOUDY CONDITIONS EVEN THROUGH THE
AFTERNOON HOURS.
A SHORTWAVE WILL DIVE SOUTH INTO THE TROUGH ON THURSDAY AND
STRENGTHEN AS IT MOVES OVER THE CWA. MODELS YESTERDAY HAD THE
SHORTWAVE STRENGTHENING JUST OFF THE COAST...ENTRAINING MOISTURE
INTO THE SYSTEM...AND BRINGING A PERIOD OF WIDESPREAD RAIN TO THE
AREA. NOW WITH THE SHORTWAVE FORECAST BY THE MODELS TO STRENGTHEN
FARTHER EAST...MOISTURE WILL BE MORE LIMITED AND GUIDANCE INDICATES
RAIN IS CONSIDERABLY LESS LIKELY WITH MOUNTAIN SHOWERS BEING THE
PRIMARY CONCERN. FOR NOW HAVE DECREASED POPS ONLY SLIGHTLY SINCE THE
MODELS ARE NOT VERY CONSISTENT FROM RUN TO RUN. RPA
.LONG TERM...FRIDAY THROUGH TUESDAY.
LATE THURSDAY NIGHT INTO FRIDAY THE GFS AND THE ECMWF BOTH SHOW
THE UPPER LEVEL TROUGH MOVING OFF TO THE EAST WITH SOME SHORT WAVE
RIDGING BUILDING IN BEHIND IT. THE GFS HAS BEEN TRENDING WEAKER
WITH THIS SYSTEM. THE ECMWF REMAINS SLIGHTLY DEEPER AND MORE
MOIST...BUT THERE IS STILL VERY LIMITED MOISTURE WITH THIS SYSTEM.
RAINFALL AMOUNTS ARE TRENDING DOWNWARD...SO REDUCED POPS A BIT.
TEMPERATURES INLAND WILL COOL FAIRLY SIGNIFICANTLY WITH THIS
SYSTEM AS WELL. FOR THE WEEKEND THE GFS BUILDS A RIDGE BACK INTO
THE AREA...WHILE THE ECMWF SWINGS ANOTHER TROUGH THROUGH. THE
RIDGE SEEMS TO HAVE A FAIRLY GOOD HOLD ON THE WEST COAST SO
TRENDED THE FORECAST TOWARDS THE GFS SOLUTION. THE GFS FINALLY
BRINGS A TROUGH THROUGH ON MONDAY WHILE THE ECMWF BUILDS A RIDGE
BACK. WILL CONTINUE TO FAVOR THE GFS...BUT CONFIDENCE ON THIS
TROUGH IS LOW. MKK
&&
.AVIATION...COASTAL CLOUDS WITH AREAS OF IFR CONDITIONS WILL
DISSIPATE THROUGH THE MORNING AND EARLY AFTERNOON AS NORTHWEST WINDS
INCREASE TODAY AND DRY AIR MIXES INTO THE COASTAL BOUNDARY LAYER.
FARTHER INLAND VFR CONDITIONS WILL PERSIST AWAY FROM COASTAL
INFLUENCED VALLEYS...WITH ANY VALLEY FOG DISSIPATING QUICKLY THIS
MORNING. A SHORTWAVE WILL MOVE TOWARD THE PACIFIC NORTHWEST COAST
TONIGHT BRINGING AN INCREASE OF COASTAL BOUNDARY LAYER MOISTURE AND
A POSSIBLE RETURN OF SOME COASTAL STRATUS...WITH THE GREATEST
CHANCES IN THE EEL RIVER VALLEY AND HUMBOLDT BAY AREA. RPA
&&
.MARINE...NORTHERLY WINDS ARE CONTINUING TO INCREASE AS HIGH
PRESSURE BUILDS IN ACROSS THE AREA. MOST RECENT MODELS AND
OBSERVATIONS ARE SHOWING WINDS TO BE SLIGHTLY HIGHER WINDS IN THE
NORTHERN OUTER WATERS THAN PREVIOUS RUNS PUSHING THEM ABOVE SMALL
CRAFT CRITERIA. THIS LOOKS TO JUST LAST THROUGH TODAY SO ISSUED IT
FOR TODAY THROUGH 9PM. TONIGHT ANOTHER WEAK TROUGH STARTS TO PUSH
THROUGH THE AREA WEAKENING THE WINDS. WINDS WILL REMAIN FAIRLY LIGHT
THURSDAY BEFORE STRENGTHENING SLIGHTLY ON FRIDAY. FOR SATURDAY LEFT
THE GOING FORECAST WHICH IS TRENDED A BIT MORE TOWARDS THE ECMWF
WITH SOME SOUTHERLY WINDS IN THE NORTHERN WATERS...WHILE THE GFS IS
STRICTLY NORTHERLY WINDS. EITHER WAY WINDS LOOK TO BE FAIRLY LIGHT
OVER THE WEEKEND IN THE NORTHERN WATERS WITH SOME SMALL CRAFT
ADVISORY CONDITIONS POSSIBLE IN THE SOUTHERN WATERS. MODELS ARE IN
DECENT AGREEMENT ON HIGH PRESSURE RETURNING AND NORTHERLY WINDS
INCREASING EARLY NEXT WEEK. MODELS ARE INDICATING WINDS OF 30 KT
WITH THIS HIGH PRESSURE.
SEAS WILL BE MAINLY DRIVEN BY THE LOCAL WINDS PEAKING AROUND 8 TO 10
FT TODAY IN THE SOUTHERN WATERS. THEY WILL ALSO COMBINE WITH A
WESTERLY WAVE OF 4 TO 6 FEET AT 10 TO 12 SECONDS. THIS WESTERLY WAVE
LOOKS TO FAIRLY CONSISTENT THROUGH THE PERIOD.
THE LONG PERIOD SOUTHERLY WAVE REMAINS FAIRLY CONSISTENT IN THE WAVE
WATCH MODEL. IT IS SHOWING IT BUILDING INTO THE AREA ON SATURDAY AT
AROUND 3 FT AT 20 SECONDS. THIS WAVE IS STILL TOO FAR OUT TO SEE HOW
THE MODEL IS HANDLING IT...BUT THE MODEL LOOKS CONSISTENT SO
CONFIDENCE IS AVERAGE WITH THIS LONG PERIOD WAVE. MKK
&&
.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING PZZ470.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT WEDNESDAY PZZ455-475.
&&
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