767
FXUS66 KEKA 072114
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
214 PM PDT TUE APR 7 2026
SYNOPSIS
WET AND UNSETTLED WEATHER WITH SHOWERS AND A CHANCE
OF THUNDERSTORMS IS EXPECTED WEDNESDAY THROUGH FRIDAY. SIGNIFICANT
COOLING, MORE RAIN, POSSIBLE THUNDERSTORMS AND HIGH MOUNTAIN SNOW
ARE ANTICIPATED FOR THIS UPCOMING WEEKEND.
DISCUSSION
DRY WEATHER WITH ABOVE NORMAL INTERIOR HIGH
TEMPERATURES WILL START TO COME TO AN END ON WEDNESDAY AS A CLOSED
500MB COLD POOL (500MB TEMPS -25C TO -23C) CENTERED NEAR 39N AND
WEST OF 135W SLOWLY BURROWS E-NE TOWARD THE NORCAL COAST TONIGHT
THROUGH FRIDAY. JUST ABOUT ALL THE MODELS HAVE THE CLOSED 500MB
COLD CORE TRACKING MUCH FARTHER NORTHWARD WITH SUBTLE VARIATIONS
IN EXACT PLACEMENT. THIS PLACEMENT PROBABLY WILL NOT MATTER TOO
MUCH IN TERMS OF PRECIP AND THUNDER CHANCES. MULTIPLE CLOUD BANDS
IN THE POSITIVELY TILTED DIFFLUENT FLOW AHEAD OF THE COLD CORE WAS
EVIDENT ON SATELLITE IMAGERY THIS AFTERNOON. ELEVATED HIGH BASED
DBZ CORES ALOFT AND SPRINKLES OUT OVER THE COAST AND WATERS LATER
TONIGHT INTO WED ARE POSSIBLE. POSITIVE TILTED DIFFLUENT SW FLOW
ALOFT WILL SHIFT EASTWARD OVER THE LAND AREAS IN ADVANCE IN THE
OFFSHORE UPPER LOW ON WED. WITH SURFACE CAPE RAMPING UP IN THE
INTERIOR (SOME MODELS NEAR 1000J/KG) AND SURFACE BASED LIFTED
INDICES NEAR -3C TO -2C, STRONGER AND MORE WIDESPREAD THUNDERSTORM
ACTIVITY APPEARS POSSIBLE WED AFTERNOON INTO EARLY EVENING IN THE
INTERIOR - MOSTLY IN TRINITY COUNTY. LATEST HREF PROBABILITIES
FOR STORMS CAPTURES THIS AREAL INCREASE. LATEST INDIVIDUAL CAMS,
PARTICULARLY THE HRRR, HAS HIGHEST DBZ CORES FIRING UP LATE IN THE
DAY OVER THE MOSTLY NE AND E TRINITY, WHILE FV3 AND OTHER WRF
MEMBERS INDICATE STORMS POSSIBLE FARTHER WEST OVER SOUTH FORK
MOUNTAIN, NW TRINITY AND IN THE YOLLA BOLLY WILDERNESS AREA. STORM
INITIATION APPEARS TO BE TIED TO DIURNAL HEATING AND TOPOGRAPHICALLY
FORCED. HENCE E AND NE TRINITY COUNTY IS PRIME TIME FOR STORMS.
STORMS FOR OTHER AREAS AND COUNTIES ARE MUCH LESS CERTAIN. ISOLATED
STRONG STORMS ARE POSSIBLE WITH THIS FIRST ROUND OF THUNDER
ACTIVITY. LOCALLY HEAVY RAIN, SMALL HAIL AND GUSTY OUTFLOW WINDS
FROM DOWNDRAFTS ARE POSSIBLE WITH WED STORMS.
SURFACE-TO-500MB S-SE BULK SHEAR (25-35KT) WILL INCREASE ACROSS
THE AREA AS THE 500MB COLD CORE EDGES INSIDE 130W ON THU SOMEWHERE
BETWEEN 35N-40N. POTENTIAL FOR STRONGER MORE LONG-LIVED STORMS
WILL INCREASE, THOUGH MUCAPE IS NOT FORECAST TO BE OVER 1000J/KG.
CAPE MAY INCREASE WITH THE MESOSCALE CONVECTIVE ALLOWING MODELS.
WITH ABOVE NORMAL PWATS NEAR 200% AND NEAR 100% SATURATION UP TO
500MB AND CAPE 950J/KG, THREAT FOR LOCALIZED TORRENTIAL DOWNPOURS
WILL INCREASE OVER THE INTERIOR. OVERALL 500MB FLOW PATTERN DOES
RESEMBLE ONE THAT IS FAVORABLE FOR STORM PROPAGATION OUT TO THE
COAST AND ADJACENT COASTAL WATERS THU. IT SEEMS ODD THAT THE NBM
HAS THE THUNDERSTORM THREAT ENDING QUICKLY AFTER PEAK HEATING FOR
MOST AREAS EXCEPT TRINITY. IF MULTI-CELL STORM CLUSTERS DEVELOP,
THUNDER ACTIVITY WILL LIKELY LAST LONGER AND CONTINUE PAST PEAK
HEATING THAN WHAT THE NBM INDICATES. ABUNDANT THICK CLOUD COVER
AND WIDESPREAD CONTINUOUS RAIN-COOLED AIR MAY SUPPRESS CONVECTIVE
INITIATION OR KEEP THE STORMS CONFINED TO THE HIGHER TERRAIN. THE
SOUTH FORK MOUNTAIN RANGE APPEARS TO BE A PRIME CANDIDATE FOR
STORMS IN THESE EASTERLY TO SOUTHEAST FLOW PATTERNS. MARGINALLY
SEVERE PULSATING STORMS ARE NOT COMPLETELY OUT OF THE QUESTION
EITHER ON THU IN THE INTERIOR. UNLIKE THE HEAT OF SUMMER, SURFACE
HEATING WILL NOT BE QUITE AS STRONG AND THE LID MAY RELEASE CAPE
MUCH SOONER.
THE CUT-OFF 500MB LOW IS FORECAST TO MEANDER SOUTH AND SOUTHEAST
JUST OFFSHORE THE CALIFORNIA COAST ON FRIDAY AND THEN BEGIN TO
EJECT EASTWARD IN RESPONSE TO AN UPSTREAM TROUGH BY FRI NIGHT.
THE WRAP MOISTURE AND UNSTABLE CONDITIONS WILL LIKELY CONTINUE TO
BRING A CHANCE FOR LOCALLY HEAVY RAIN AND THUNDERSTORMS TO MOSTLY
THE INTERIOR ON FRIDAY. ONCE AGAIN THESE E-SE DIFFLUENT WIND FLOW
PATTERNS AT 500MB ARE FAVORABLE FOR STORMS TO PROPAGATE OUT OVER
COASTAL AREAS INTO FRI.
WET AND UNSETTLED WEATHER WILL MOST LIKELY CONTINUE INTO THE
WEEKEND. NEARLY ALL THE MODELS HAVE A COLDER TROUGH (THE UPSTREAM
KICKER) DROPPING DOWN FROM THE NW THIS WEEKEND. MOST ALL THE
MODELS HAVE TRENDED MUCH WETTER AS YET ANOTHER CLOSED LOW IMPACTS
THE FORECAST AREA WITH RAIN, HIGH MOUNTAIN SNOW AND GUSTY NW TO W
WINDS. SNOW MAY OCCUR OVER THE HIGHEST MOUNTAIN PEAKS TOO,
GENERALLY ABOVE 4KFT, WITH THE WEEKEND STORM. IT WILL MOST LIKELY
(80% CHANCE) BE MUCH COLDER IN THE INTERIOR TOO. SUBFREEZING
MINIMUM TEMPERATURES AND FROST WILL POSSIBLE FOR THE INTERIOR
VALLEYS BY SUNDAY MORNING WHILE DAYTIME HIGHS STRUGGLE TO REACH
60F. THERE IS STILL A GREAT DEAL OF VARIABILITY AND SPREAD IN THE
PRECIP AMOUNTS 4 AM SAT THRU 11 PM SUN, RANGING FROM A FEW HUNDREDTHS
IN 12 HOURS (NBM 25TH PERCENTILE) TO 0.50 TO 1.50 INCHES IN 12
HOURS (NBM 90TH PERCENTILE). THIS IS BASED ON OLDER NBM DATA AND
NEWER NBM MAY COME IN WETTER. THERE IS A CHANCE FOR LOW TOPPED
THUNDERSTORMS WITH LOCALLY HEAVY PRECIP AND SMALL HAIL THIS
WEEKEND WITH COLD 500MB TEMPERATURES AND LOWER SNOW LEVELS. BY
MONDAY AND TUESDAY (APR 13 AND 14), PRECIP POTENTIAL WILL FINALLY
START TO DWINDLE AS 500MB TEMPERATURES BEGIN TO WARM AND A RIDGE
BUILDS OFFSHORE. STAY TUNED TO OUR LATEST FORECAST FOR MORE
DETAILS AND POSSIBLE WATCHES, WARNINGS AND ADVISORIES.
AVIATION
COASTAL TERMINALS REMAIN UNDER A STRATUS LAYER KEEPING
CONDITIONS AT IFR-MVFR THROUGH THE MORNING. SATELLITE IMAGERY
SHOWS THIS CLOUD BANK ENGULFING MOST OF THE NORTHERN CALIFORNIA
COASTLINE. WHILE THIS CLOUD BANK LOOKS TO BE EVAPORATING ON THE
COASTAL AREAS AWAY FROM TERMINALS, THE INVERSION SEEMS TO BE
HOLDING AT TERMINAL SITES. MODELS EVEN SHOW THIS BANK
RESTRENGTHENING TONIGHT AROUND 04- 06Z. INLAND TERMINALS CAN
EXPECT VFR CONDITIONS WITH DIURNAL TERRAIN- DRIVEN WINDS WITH THE
POSSIBILITY OF AFTERNOON UP-VALLEY GUSTS UP TO 15-20KTS. AFTER 18Z
04/08, RAIN AND INLAND THUNDERSTORMS CHANCES CONTINUE DUE TO A
SURFACE LOW PRESSURE CENTER FLOWING TOWARDS NW CA.
MARINE
VERY GENTLE TO CALM NORTHWEST WINDS AND CALM SEAS WILL PERSIST
TODAY. LOW PRESSURE SLOWLY PASSING TO THE SOUTH WILL TURN WEAK WINDS
EASTERLY AROUND WEDNESDAY AND THEN BRING VERY SLIGHTLY ENHANCED
NORTHERLIES LATE WEEK. THERE REMAINS RELATIVELY HIGH WIND STRENGTH
UNCERTAINTY DEPENDING ON THE TRACK OF THE LOW. THE ENSEMBLE MEAN
SHOWS GUSTS ONLY TO AROUND 16 KTS BY FRIDAY IN THE OUTER WATERS,
BUT THERE IS A 10% CHANCE OF GUSTS CLOSER TO 25 KTS. NORTHERLY
WINDS WILL CONTINUE TO STRENGTHEN INTO THE WEEKEND. REGARDLESS,
THERE IS LITTLE TO NO SWELL AND SEA WILL BE DOMINATED BY WHATEVER
SHORT PERIOD SEAS THE WIND CAN GENERATE. /JHW
EKA WATCHES/WARNINGS/ADVISORIES
CA...
NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
NONE.
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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