071
FXUS66 KEKA 070715
AFDEKA
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
1215 AM PDT TUE APR 7 2026
SYNOPSIS
AN APPROACHING CUTOFF AREA OF LOW PRESSURE WILL BRING
SHOWERS AND INTERIOR THUNDERSTORMS ON WEDNESDAY, WITH INCREASING
CHANCES ON THURSDAY. CHANCE FOR SHOWERS AND THUNDERSTORMS FROM THE
LOW WILL CONTINUE ON FRIDAY AND POSSIBLY INTO THE WEEKEND. A SECOND
MUCH COLDER LOW WILL BRING ADDITIONAL PRECIPITATION CHANCES
THROUGH THE LATER HALF OF THE WEEKEND.
DISCUSSION
A WEAK FRONTAL BOUNDARY BROUGHT OVERNIGHT CHANCES FOR
COASTAL LIGHT DRIZZLE AND A LESSENING CHANCE FOR WIDESPREAD FOG. A
CUTOFF 500MB CLOSED LOW IS ADVANCING CLOSER TO THE CALIFORNIA COAST
TUESDAY. PRECIPITATION CHANCES BEGIN TO INCREASE LATE TUESDAY
NIGHT FROM THE NEARING LOW. A LONE, WEAK SHOWER OR TWO MAY BRUSH
THE NORTH COAST LATE TUESDAY, BUT SHOWER CHANCES WILL NOT
SIGNIFICANTLY INCREASE UNTIL WEDNESDAY AFTERNOON. THE DEEPENED
MARINE STRATUS IS FORECAST TO REMAIN FAIRLY WELL EMBEDDED OVER THE
COASTAL ZONES TO DAMPEN DOWN DAYTIME HIGHS.
INCREASING INSTABILITY WILL BRING CHANCES FOR THUNDERSTORMS STARTING
WEDNESDAY AFTERNOON FOR THE INTERIOR. EARLY ANALYSIS OF THE
SOUNDINGS SHOWS A SURGE SUBTROPICAL MOISTURE TO BE BROUGHT IN WITH
THE LOW, INCREASING PWATS TO 200% OF NORMAL. INTERIOR AREAS THROUGH
TRINITY COUNTY ARE MOST FAVORED FOR THUNDERSTORM DEVELOPMENT
WEDNESDAY (15 TO 20%). THERE IS TYPICALLY A DELAY IN SURFACE
SATURATION, EVIDENT BY INVERTED V PROFILES EARLY IN THE AFTERNOON.
THIS WILL SUPPORT SOME STRONGER DOWNDRAFT WIND GUSTS WITH ANY
INITIAL ISOLATED THUNDERSTORMS. THERE WILL BE "THIN" CAPE, BUT
MODESTLY HIGH FOR THE REGION AT 300 TO 400 AND EVENTUALLY LOCALLY
OVER 500 J/KG.
THE LOW BRUSHES CLOSER TO THE NORTH COAST THURSDAY WHEN HIGHER
CHANCES FOR SHOWERS AND THUNDERSTORM (20-30%) DEVELOP AS A RESULT.
BROAD FORCING MAXIMIZES LATE THURSDAY AROUND THE LOW WITH DEEP-
LAYER SHEAR INCREASING TO 30 TO 40 KTS. SOUTHEAST STEERING FLOW WILL
ALLOW FOR INTERIOR, POSSIBLY ORGANIZED STORM CLUSTERS TO ATTEMPT TO
PROPAGATE WESTWARD TOWARD THE COAST. PRECIPITABLE WATER VALUES LOOK
TO NEAR AT LEAST 0.9 INCHES, SO GUSTY WINDS AND LOCALLY HEAVY
RAINFALL WILL BE POSSIBLE IF DESTABILIZATION IS FULLY REALIZED. THE
THERMODYNAMIC PROFILE MORE CLASSICALLY SUPPORTS HAIL GROWTH, WITH
STEEP LAPSE RATES REACHING 7 C/KM. MORE SHOWER AND THUNDERSTORM
CHANCES CONTINUE THROUGH FRIDAY AND POSSIBLE SATURDAY (UP TO 20%).
BEYOND FRIDAY INTO NEXT WEEKEND, WET AND COOLER WEATHER MAY RETURN
ON SAT OR SAT NIGHT AS AN UPSTREAM AND POTENTIALLY MUCH COLDER
TROUGH COMES BARRELING DOWN FROM THE NW. THIS TROUGH COULD BRING A
CHANCE FOR SNOW TO THE HIGHEST MOUNTAIN PEAKS. THERE ARE
CONSIDERABLE DIFFERENCES IN THE ENSEMBLES AND OTHER OUTCOMES ARE
POSSIBLE, INCLUDING A WARMER AND DRIER SCENARIO. WEAK INSTABILITY
AND COLDER TEMPERATURES ALOFT MAY BRING AN ENVIRONMENT FOR SMALL
HAIL DEVELOPMENT IF THE COLDER SCENARIO OCCURS.
AVIATION
MARINE INFLUENCE HAS PERSISTED OVER THE AREA. THAT SAID,
WEAKENING HEAT OVER THE INTERIOR COMBINED WITH APPROACHING LOW
PRESSURE HAVE HELPED FORM A MORE LIFTED AND EXPANSIVE MARINE LAYER.
THIS HAS BROUGHT IFR CEILINGS ALL ALONG THE COAST. SOME BRIEF
LOWERING TO LIFR IS POSSIBLE (30% CHANCE) AROUND SUNRISE, BUT ANY
SUCH CONDITIONS WILL BE SHORT LIVED. MARINE STRATUS WILL MOST LIKELY
STAY ROBUST ALONG THE COAST TOMORROW (80% CHANCE) BUT WILL MOST
LIKELY LIFT AT LEAST TO MVFR. CEILINGS ARE EXPECTED TO LOWER AGAIN
TUESDAY NIGHT. /JHW
MARINE
VERY GENTLE TO CALM NORTHWEST WINDS WILL PERSIST INTO
TUESDAY. SIMILARLY CALM SEAS WILL PERSIST AS WELL. 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
20% 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.
VISIT US AT HTTPS://WWW.WEATHER.GOV/EUREKA
FOLLOW US ON FACEBOOK AND TWITTER AT:
HTTPS://WWW.FACEBOOK.COM/NWSEUREKA
HTTPS://WWW.TWITTER.COM/NWSEUREKA
FOR FORECAST ZONE INFORMATION
SEE THE FORECAST ZONE MAP ONLINE:
HTTPS://WWW.WEATHER.GOV/IMAGES/EKA/ZONEMAP.PNG
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page