AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
235 PM PST TUE FEB 20 2018

.SYNOPSIS...SEVERAL WEAK WEATHER SYSTEMS WILL BRING PERIODS OF
RAIN AND SNOW TO THE AREA TONIGHT THROUGH THURSDAY. COLD AND DRY
CONDITIONS ARE EXPECTED AGAIN FRIDAY MORNING. THERE IS THE
POTENTIAL FOR MORE RAIN AND SNOW FOR THE WEEKEND AND INTO EARLY
NEXT WEEK.

&&

.DISCUSSION...A WEAK SHORTWAVE TROUGH MOVING DOWN FROM THE
NORTHWEST THIS AFTERNOON IS BRINGING MID LEVEL CLOUDS TO THE AREA.
THERE IS SOME PRECIPITATION ASSOCIATED WITH THIS, BUT MODELS ARE
STRUGGLING ON THE QPF AMOUNTS. THE HI-RES MODELS ARE SHOWING QPF
AMOUNTS OF A TRACE TO A THIRD OF AN INCH. GENERALLY WENT WITH A
BLEND FOR LESS THAN A QUARTER OF AN INCH. SNOW LEVELS REMAIN
AROUND 1,000 TO 1,500 FEET. SNOW ACCUMULATIONS OF UP TO 2 INCHES
ARE POSSIBLE TONIGHT AND WEDNESDAY MORNING. THE CLOUD COVER WILL
KEEP TEMPERATURES FROM BEING AS COLD AS LAST NIGHT, ALTHOUGH IT
WILL STILL BE A CHILLY NIGHT WITH TEMPERATURES IN THE UPPER 20S
AND 30S.

WEDNESDAY NIGHT INTO THURSDAY MORNING ANOTHER COLD SYSTEM IS
EXPECTED TO BRING SOME LIGHT RAIN AND SNOW TO THE REGION. AGAIN
AMOUNTS WILL LIGHT, ONLY UP TO AN INCH OR TWO. IT LOOKS LIKE THERE
WILL BE ENOUGH INSTABILITY WE COULD SEE SOME SMALL HAIL ALONG THE
HUMBOLDT AND DEL NORTE COAST. RAIN, SNOW, AND HAIL AMOUNTS LOOK
LIGHTER THAN THE PREVIOUS EVENT.

THURSDAY NIGHT INTO FRIDAY MORNING SKIES ARE EXPECTED TO CLEAR OUT
AND HIGH PRESSURE BUILDS IN. THERE WILL BE SUBSIDENCE AND CLEARING
SKIES, HOWEVER IT WILL BE BREEZY. THERE IS THE POTENTIAL FOR
ANOTHER COLD NIGHT AND HARD FREEZE WARNING FOR THE COASTAL AREAS,
ALTHOUGH IT MAY ONLY BE IN THE PROTECTED AREAS.

SATURDAY THE 12Z GFS AND THE 00Z ECMWF SHOW ANOTHER SYSTEM
BRINGING SOME RAIN AND SNOW TO THE AREA. THE GFS SHOWS THIS MOVING
THROUGH QUICKLY WITH VERY LITTLE SNOW, HOWEVER THE 00Z ECMWF HAS
THE COLD AIR AND PRECIP LINGERING OVERNIGHT SATURDAY NIGHT INTO
SUNDAY. CONFIDENCE IS LOW ON THIS AT THIS POINT. THERE IS BETTER
AGREEMENT ON A STRONGER SYSTEM BRINGING RAIN AND SNOW TO THE AREA
SUNDAY NIGHT AND MONDAY. MKK

&&

.AVIATION...AN APPROACHING WEATHER DISTURBANCE CONTINUED TO
SLOWLY BE DRIVEN TOWARD THE REDWOOD COAST TODAY. BY NOONDAY,
COASTAL AIR TERMINALS WERE INUNDATED WITH MOSTLY CIG050 AND
GREATER. A VISUAL 12:30 PM RADAR (KBHX) PICTURE SHOWED LIGHT RAIN
AND/OR VIRGA NEARING THE NORTH COAST. THEREFORE, CLOUDS WILL
CONTINUE TO THICKEN AND LOWER THIS AFTERNOON WITH LIGHT
RAIN/DRIZZLE IMMINENT IN THE FAR NORTH COAST...THEN GENERALLY
INCREASING AND SPREADING ASHORE MID-LATE AFTERNOON. IMPACTS AT
COASTAL AND NEAR COASTAL HILL`S AIRPORTS AND AIRFIELDS EXPECTED TO
REMAIN MINIMAL AS MODELS ONLY REDUCE CIGS/VIS INTO MVFR THIS
EVENING. HIGHER TERRAIN, SUCH AS COASTAL RANGES AND INTERIOR
AREAS, WILL ALSO SEE THE SPREAD OF THICKENING CLOUDS...AS WELL AS
RAIN AND/OR SNOW THIS EVENING. INTERIOR MENDOCINO, INCLUDING UKI
CAN EXPECT TO SEE LIGHT RAIN STARTING EARLY-MID WEDNESDAY MORNING.
/TA

&&

.MARINE...WINDS HAVE BECOME LIGHT AND SOUTHERLY THIS AFTERNOON.
THESE ARE EXPECTED TO INCREASE A BIT TONIGHT, ESPECIALLY N OF
CAPE MENDOCINO AHEAD OF THE APPROACHING FRONTAL SYSTEM. WINDS WILL
SHIFT BACK TO NORTHERLY BY WEDNESDAY AFTERNOON AND INCREASE TO
BORDERLINE ADVISORY CRITERIA, 20 TO 25 KT, BY WEDNESDAY NIGHT.
NORTHERLIES WILL FURTHER INCREASE ON THURSDAY WITH GALE FORCE
GUSTS POSSIBLE IN AT LEAST THE OUTER WATERS. N WINDS WILL DECREASE
AGAIN DURING THE DAY FRIDAY FROM N TO S.

A NW SWELL OF 5 TO 6 FEET WILL PERSIST ACROSS THE WATERS THIS
AFTERNOON AND DECAY THROUGH THURSDAY. ANOTHER NW SWELL WILL ENTER
THE WATERS THURSDAY AFTERNOON AND DECAY THROUGH THE END OF THE
FORECAST PERIOD. LARGER NW SWELL AT BETWEEN A 9 AND 11 SECOND
PERIOD WILL PERSIST THROUGH MUCH OF THE PERIOD AS STRONGER N WINDS
DEVELOP FARTHER OFFSHORE THE LOCAL MARINE AREA. /SEC/MKK

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...NONE.

&&