189
FXUS66 KEKA 170725
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
1225 AM PDT MON AUG 17 2026
KEY MESSAGES
* SMOKE REMAINS OVER AREAS OUTSIDE OF THE MARINE LAYER DUE TO LOCAL
AND DISTANT WILDFIRES.
* INTERIOR TEMPERATURES ARE EXPECTED TO REMAIN NEAR NORMAL THROUGH
THROUGH FIRST HALF OF THE WEEK WITH HIGHS IN THE LOW TO MID 90S.
* ANOTHER TROUGH IS EXPECTED TO BRING BELOW NORMAL TEMPERATURES
AND THE POTENTIAL FOR A FEW THUNDERSTORMS LATE IN THE WEEK.
SYNOPSIS
A SERIES OF UPPER LEVEL TROUGHS OFF THE WEST COAST ARE
EXPECTED TO GENERALLY KEEP INLAND TEMPERATURES NEAR NORMAL.
PERSISTENT MARINE CLOUDS EXPECTED ALONG THE COAST WITH SOME
AFTERNOON CLEARING. LATE IN THE WEEK, A STRONGER TROUGH WILL BRING
COOLER INLAND TEMPERATURES AND EVEN THE POTENTIAL FOR INLAND
THUNDERSTORMS.
DISCUSSION
A VERY BRIEF SHORTWAVE RIDGE HAS BUILT OVER NW CA.
OFFSHORE FLOW IN DEL NORTE COUNTY WILL LIKELY KEEP THE COAST CLEAR
THROUGH MOST OF THE EVENING. MONDAY, ANOTHER TROUGH APPROACHES FROM
THE SOUTHWEST. TEMPERATURES ARE EXPECTED TO BE CLOSE TO AVERAGE
AGAIN, YET SOME SMOKE IN THE NORTHERN VALLEYS COULD KEEP TEMPS. IN
THE LOW 90S. SOME HIGH CLOUDS ARE EXPECTED TO MOVE OVER THE AREA IN
THE AFTERNOON, AS A SHORTWAVE DISTURBANCE MOVES OVER THE AREA. THERE
WILL BE MINOR INSTABILITY WITH THIS FEATURE, YET IT DOESN'T LOOK
LIKE THERE WILL BE ENOUGH MOISTURE FOR ANY THUNDERSTORMS. IF
ANYTHING, THIS LIFT COULD SIMPLY HELP MOVE SMOKE AWAY FROM THE
VALLEYS, WHICH WOULD BE BENEFICIAL.
TUESDAY THE RIDGE BUILDS BACK TO THE WEST AND WILL EVER SO SLIGHTLY
INCREASE INLAND TEMPERATURES ABOVE NORMAL BACK TO THE MID TO HIGH
90S. COASTAL CLOUDS MAY SEE A FEW BREAKS IN THE AFTERNOON, BUT ARE
GENERALLY EXPECTED TO BE PRETTY PERSISTENT, YET AGAIN. WEDNESDAY,
THE ANOTHER PUSH OF ENERGY FROM AN UPPER LEVEL TROUGH IN THE EAST
PACIFIC STARTS TO PUSH THE RIDGE TO THE EAST, HOWEVER, THIS WILL NOT
IMPACT THE AREA UNTIL LATE WEEK.
THURSDAY AND FRIDAY, THE AFOREMENTIONED UPPER LEVEL TROUGH IS
EXPECTED TO MOVE BY THE AREA. A COUPLE OF THE MODEL CLUSTERS ARE
CONTINUING TO SHOW THE VORTICITY LINING UP WITH THE AFTERNOON
HEATING ON FRIDAY. THIS ALIGNMENT INCREASE THE LIKELIHOOD OF STORMS,
YET ONLY BY A MINUSCULE AMOUNT AS OF RIGHT NOW. THERE CONTINUES TO
BE A LOT OF UNCERTAINTY IN HOW MUCH MOISTURE AND INSTABILITY THERE
WILL BE. THIS WILL NEED TO MONITORED AS IT GETS CLOSER.
AVIATION
THE MARINE LAYER CONTINUES TO EBB AND FLOW OVER NORTH
COAST TERMINALS THIS EVENING WITH SOUTHERLY FLOW DOMINATING. HIGH
CLOUDS CONTINUE TO BLOCK IR SATELLITE IMAGERY OF THIS FEATURE,
YET COASTAL OBSERVATIONS CONTINUE TO SHOW THAT AREAS UNDER THE
MARINE STRATUS WILL BE FOGGY (VIS <1/2SM). BRIEF AFTERNOON
CLEARING TO VFR WITH NORTHERLY WINDS ARE EXPECTED FOR COASTAL
TERMINALS AND RIVER VALLEYS INLAND. STRATUS IS FORECASTED TO
RETURN AGAIN.
MARINE
NORTHERLY WIND ARE EXPECTED TO INCREASE IN THE OUTER
WATERS OVERNIGHT TO AROUND 20 TO 25 KT. THESE WINDS ARE STRONG
ENOUGH TO CREATE SMALL CRAFT ADVISORY CONDITIONS FOR THE THE
OUTER WATERS DUE TO STEEP SHORT PERIOD WAVES IN AREAS DOWNWIND OF
CAPE MENDOCINO AND PT. ST. GEORGE. CLOSER TO THE COAST, HIGH
RESOLUTION MODELS SHOW SOUTHERLY WINDS CONTINUING THROUGH THE
EVENING. A SMALL PERIOD SOUTHERLY SWELL CONTINUES AT AROUND
3FT@17S.
THROUGH THE DAY, THE NORTHERLY WINDS ARE EXPECTED TO DIMINISH AS AN
UPPER LEVEL SHORTWAVE DISTURBANCE MOVES OVER NW CA WHICH WILL LIKELY
CAUSE THE END TO THE SMALL CRAFT ADVISORY. THE SOUTHERLY SWELL IS
EXPECTED TO CONTINUE. HIGH PRESSURE BRIEFLY RETURNS TUESDAY AND
WEDNESDAY WHICH WILL INCREASE NORTHERLY WINDS TO AROUND 20 TO 25 KT.
THURSDAY AND FRIDAY, ANOTHER UPPER TROUGH IS EXPECTED TO FLOW OVER
NW CA CAUSING WINDS TO DIMINISH AGAIN WITH THE POTENTIAL FOR LOCAL
SOUTHERLY WINDS NEAR THE COAST.
FIRE WEATHER
THE MAIN CHALLENGE FOR THE FIRE WEATHER FORECAST
IS THE POTENTIAL FOR THUNDERSTORMS. MONDAY AFTERNOON A SHORTWAVE
MOVES THROUGH, BUT AT THIS POINT IT STILL DOESN'T LOOK LIKE IT
THINGS WILL LINE UP FOR ANY THUNDERSTORMS. THERE MAY BE SOME
INCREASED INSTABILITY, BUT NOT ENOUGH MOISTURE FOR ANY SHOWERS OR
THUNDER. TUESDAY THROUGH EARLY THURSDAY, WEAK HIGH PRESSURE IS
EXPECTED TO BRING DRY AND FAIRLY STABLE CONDITIONS. THURSDAY NIGHT
INTO FRIDAY, ANOTHER TROUGH IS EXPECTED TO APPROACH THE AREA. AT
THIS POINT IT IS STILL HARD TO TELL IF THE MOISTURE INSTABILITY AND
LIFT WILL LINE UP TO GET THUNDERSTORMS, BUT IT IS POSSIBLE. THIS
WILL CONTINUE TO BE WATCHED THROUGH THE WORK WEEK. MKK
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR PZZ470.
SMALL CRAFT ADVISORY UNTIL 9 AM PDT THIS MORNING FOR PZZ475.
NOTE: THE FULL FORECAST DISCUSSION IS NOW REGULARLY ISSUED BETWEEN
10 AM/PM AND 1 PM/AM. ADDITIONAL UPDATES WILL BE ISSUED AS NEEDED.
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