Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 241152
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
352 AM PST MON NOV 24 2014

.SYNOPSIS...A WEAK WARM FRONT MAY BRING SOME LIGHT RAIN OR
SPRINKLES TODAY FOR AREAS PRIMARILY NORTH OF CAPE MENDOCINO. HIGH
PRESSURE AND DRY CONDITIONS RETURN TUESDAY THROUGH THURSDAY
MORNING. WET WEATHER RETURNS THURSDAY AFTERNOON INTO THE WEEKEND.

&&

.SHORT TERM (THROUGH THURSDAY)...A WEAK WARM FRONT CONTINUES TO
APPROACH THE COAST THIS MORNING. RAIN AMOUNTS LOOK TO BE VERY
LIGHT WITH THIS FRONT. MODELS HAVE PUSHED BACK MOST OF THE RAIN
UNTIL LATE MORNING OR AFTERNOON. THERE MAY STILL BE SOME SPRINKLES
IN THE MORNING NORTH OF CAPE MENDOCINO WITH AREAS TO THE SOUTH
REMAINING MAINLY DRY. RAINFALL AMOUNTS WILL RANGE FROM A TRACE TO
A TENTH OF AN INCH OVER THE HIGHER TERRAIN IN DEL NORTE COUNTY.
FOG IS BEING REPORTED IN THE VALLEYS OF TRINITY AND MENDOCINO
COUNTIES. THIS WILL LIKELY SLOW DOWN THE WARMING ONCE AGAIN IN
THESE VALLEYS.

TUESDAY AND WEDNESDAY WILL BE MAINLY CLEAR EACH DAY WITH THE
EXCEPTION OF THE INLAND VALLEYS WHERE THERE WILL BE NIGHT AND
MORNING FOG. THIS WILL LIKELY BE SLOW TO CLEAR EACH
DAY...ESPECIALLY IN TRINITY COUNTY SO HAVE LOWERED THE HIGH
TEMPERATURES THERE. MORNING TEMPERATURES WILL BE CHILLY...ALTHOUGH
IT REMAINS TO BE SEEN HOW MUCH FOG WILL BE PRESENT TO KEEP
TEMPERATURES A BIT WARMER. TUESDAY MORNING WILL LIKELY BE THE
COLDEST...BY WEDNESDAY THE SOUTHEASTERLY WINDS START TO INCREASE
AHEAD OF THE THE NEXT SYSTEM. AT THIS POINT IT DOES NOT APPEAR
THERE WILL BE FROST IN THE COASTAL ZONES OR NORTH COAST INTERIOR
ZONE (INTERIOR PORTIONS OF HUMBOLDT AND DEL NORTE COUNTY)...BUT
THIS WILL NEED TO BE WATCHED AS IT GETS CLOSER.

THE 00Z GFS HAS SPED UP THE FRONT SLIGHTLY AND IS NOW BRINGING
RAIN TO THE NORTH COAST IN THE AFTERNOON ON THANKSGIVING DAY. THE
ECMWF HAS COME INTO BETTER AGREEMENT WITH THE GFS AND IS ALSO
BRINGING SOME LIGHT RAIN IN ON THURSDAY AFTERNOON. SO HAVE
INCREASED POPS SLIGHTLY FOR THE NORTH COAST ON THURSDAY AFTERNOON
THIS WILL NEED TO BE MONITORED AS IT GETS CLOSER. SNOW LEVELS WILL
BE MAINLY HIGH WITH THIS SYSTEM...ALTHOUGH THERE COULD BE SOME
COLD AIR TRAPPED IN THE WEAVERVILLE TO TRINITY LAKE AREA WHICH
COULD LOWER SNOW LEVELS A BIT EARLY ON. MKK

LONG TERM...(FRIDAY THROUGH MONDAY) ONCE THE FRONT MOVES
ONSHORE...EITHER DURING THE DAY THURSDAY OR THURSDAY
NIGHT...WET CONDITIONS WILL PERSIST FOR SEVERAL DAYS. WAVES OF
UPPER LEVEL ENERGY IN ONSHORE FLOW ADVANCE TOWARD THE COAST FRIDAY
THROUGH SUNDAY. MODELS ARE STILL IN REMARKABLE CONSISTENCY ON THIS
PATTERN WITH WIDESPREAD PRECIPITATION EXPECTED FOR THE AREA. THERE
ARE DIFFERENCES IN THE TIMING OF EACH WAVE OF PRECIPITATION AND
WHERE EXACTLY THE HEAVIEST PRECIPITATION FALLS ACROSS NORTHWEST
CALIFORNIA...BUT CONFIDENCE IS VERY HIGH THAT WE ARE HEADED INTO A
WET PERIOD. THE GFS AND ECMWF BOTH CURRENTLY PREDICT A TOTAL OF 2
TO 6 INCHES OF RAIN FROM LATE THURSDAY THROUGH SUNDAY...WITH THE
HIGHEST AMOUNTS IN THE MOUNTAINS AS USUAL. SNOW WILL REMAIN HIGH
THROUGH EARLY SUNDAY WITH A WARM AIRMASS IN PLACE WITH TROPICAL
ORIGINS. SUNDAY NIGHT INTO THERE IS FAIRLY GOOD MODEL AGREEMENT
THAT THE UPPER LEVEL TROUGH WILL MOVE OVERHEAD AND SNOW LEVELS
WILL FALL BELOW 4000 FT AND MAY CAUSE TRAVEL DIFFICULTIES ON THE
HIGHER PASSES. MKK/RPA

&&

.AVIATION...MUCH OF NORTHERN CALIFORNIA WILL WAKE UP TO VFR
CONDITIONS TODAY WITH THE EXCEPTION OF AREAS OF IFR ACROSS
INTERIOR VALLEYS AND POSSIBLY SMALL POCKETS ALONG THE COAST.
INTERIOR VALLEY FOG SHOULD DISSIPATE BY LATE MORNING. A PASSING
WARM FRONT WILL CAUSE CEILINGS TO GRADUALLY LOWER ACROSS THE
REGION TODAY WITH PERIODIC LIGHT RAIN POSSIBLE FOR AIRFIELDS NORTH
OF CAPE MENDOCINO. THERE IS STILL SOME UNCERTAINTY AS TO WHEN
CONDITIONS WILL DETERIORATE AND TO WHAT DEGREE. ULTIMATELY DECIDED
TO CONTINUE TO TREND CLOSER WITH THE NAM. EXPECT MVFR CONDITIONS
FOR AREAS NORTH OF CAPE MENDOCINO BY LATE AFTERNOON WITH PERIODS
OF IFR CONDITIONS POSSIBLE TONIGHT. AREAS FARTHER INLAND AND SOUTH
OF CAPE MENDOCINO CAN EXPECT VALLEY FOG ONCE AGAIN TONIGHT WITH
OTHERWISE VFR CONDITIONS ELSEWHERE.

&&

.MARINE...A WARM FRONT WILL TRAVERSE ACROSS THE WATERS TODAY
RESULTING IN MINIMAL MARINE IMPACTS INCLUDING A SLIGHT INCREASE IN
WINDS OFFSHORE AND PERIODS OF LIGHT RAIN. LIGHT TO MODERATE WINDS
SHALL PERSIST THROUGH THE EARLY HALF OF THE WEEK AS HIGH PRESSURE
OVER HEAD MAINTAINS A WEAK GRADIENT. FURTHERMORE A NORTHWESTERLY
WAVE WILL SLOWLY SUBSIDE TODAY THROUGH MID-WEEK. SEA HEIGHTS WILL
FLUCTUATE NEAR 10 FEET MID-DAY AND SHOULD FURTHER SUBSIDE TO
AROUND 8 TO 9 FEET AT 13 SECONDS BY TONIGHT. CONSEQUENTLY, SMALL
CRAFT ADVISORIES SHOULD BE GOOD TO EXPIRE BY LATE THIS AFTERNOON.
A LOW PRESSURE SYSTEM WILL THEN APPROACH THE REGION CAUSING
INCREASING SOUTHERLY WINDS AND BUILDING SEAS ACROSS THE COASTAL
WATERS BY WEDNESDAY/THURSDAY. BEYOND THAT LITTLE WAS CHANGED IN
THE FORECAST OVER THE WEEKEND AS MODELS STILL EXHIBIT DIFFERENCES
IN TIMING OF THIS MAIN SYSTEM AND THE SUBSEQUENT DISTURBANCES.
THUS I CONTINUED TO SKEW TOWARDS ECMWF FOR THE WEEKEND WINDS BUT
LOWERED THEM SLIGHTLY TO FALL INTO CONSISTENCY WITH NEIGHBORS.
/KML

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 2 PM PST THIS AFTERNOON FOR
     PZZ450-455-470-475.

&&

$$

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