Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 312230
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
330 PM PDT THU JUL 31 2014

.SYNOPSIS...ISOLATED THUNDERSTORMS ARE POSSIBLE OVER THE TRINITY
HORN ONCE AGAIN THIS AFTERNOON AND EVENING. A SLIGHT CHANCE OF
THUNDERSTORMS WILL CONTINUE OVER THE EASTERN MOUNTAINS THROUGH THE
WEEKEND. COASTAL CLOUDS AND FOG CAN BE EXPECTED MOST NIGHTS AND
MORNINGS WITH ABOVE NORMAL TEMPERATURES CONTINUING ACROSS THE
INTERIOR.

&&

.SHORT TERM (TONIGHT THRU SUN NIGHT)...AS OF 22Z VISIBLE SATELLITE
IMAGERY SHOWED STRATUS ALONG MUCH OF THE REDWOOD AND MENDOCINO
COASTS. CUMULUS WAS FOUND ACROSS THE HIGHER TERRAIN OF
TRINITY COUNTY. NORTHWEST CALIFORNIA REMAINS BETWEEN BROAD UPPER
TROUGHING OVER THE NORTHEAST PACIFIC AND A RIDGE OF HIGH PRESSURE
OVER THE DESERT SOUTHWEST. SHORTWAVES CONTINUE TO PASS OVER THE
AREA EACH DAY WHILE MONSOONAL MOISTURE IS BEING TRANSPORTED AROUND
THE HIGH AND INTO THE AREA.

ISOLATED THUNDERSTORMS ARE POSSIBLE AGAIN THIS AFTERNOON AND
EVENING OVER THE TRINITY HORN AS A WEAK DISTURBANCE COMBINES WITH
ATMOSPHERIC INSTABILITY. THE INSTABILITY IS CONFIRMED BY MID-
LEVEL LAPSE RATES OF 7 TO 9 C/KM...LI VALUES DOWN TO -5C....AND
SBCAPE VALUES OF 500 TO 1500 J/KG. A MID-LEVEL STABLE LAYER IS
ONCE AGAIN PRESENT ACROSS THE AREA AND BUILD-UPS HAVE ONCE AGAIN
BEEN STRUGGLING TO BREAK THROUGH. THINK THAT AN APPROACHING JET
STREAK AND FAVORABLE PVA LOCATION SHOULD PRODUCE ENOUGH LIFT FOR
PERHAPS A FEW THUNDERSTORMS TO DEVELOP. ANY THUNDERSTORM THAT
FORMS WILL BE MOVING OFF TO THE NORTHEAST. HAVE KEPT THE SLIGHT
CHANCE OF THUNDERSTORMS OVER THE EASTERN MOUNTAINS IN THE FORECAST
EACH AFTERNOON AND EVENING INTO THE WEEKEND AS THE MODELS CONTINUE
TO SHOW INSTABILITY. THIS WILL NEED TO BE MONITORED.

COASTAL CLOUDS/FOG CAN BE EXPECTED MOST NIGHTS/MORNINGS. ADDED
PATCHY SMOKE TO THE FORECAST IN NORTHERN MENDOCINO...SOUTHERN
HUMBOLDT...AND SOUTHERN TRINITY COUNTIES DUE TO THE LODGE FIRE IN
NORTHWEST MENDOCINO COUNTY. HIGH TEMPERATURES ACROSS INTERIOR VALLEY
LOCATIONS WILL RANGE FROM THE 90S TO LOWER 100S F...WITH 60S AND 70S
F ALONG THE COAST. STP

&&

.LONG TERM...(MON THRU THU) MODEL GUIDANCE CONTINUES TO PLACE
NORTHWEST CALIFORNIA ON THE WEST SIDE OF AN UPPER LEVEL RIDGE
THROUGH THE PERIOD. THE GFS AND ECMWF BOTH PREDICT THAT A WEAK CUT
OFF LOW MAY FORM OFF THE CENTRAL CALIFORNIA COAST MID NEXT WEEK
ALLOWING SOME MODERATE SOUTHERLY FLOW TO DEVELOP. THIS WOULD LET
MOISTURE FLOW UP THE CENTRAL VALLEY POSSIBLY ENHANCING THUNDERSTORM
POTENTIAL. HOWEVER THE MODEL GUIDANCE HAS NOT BEEN CONSISTENT WITH
THE TIMING AND ABUNDANCE OF MOISTURE. THUS CONFIDENCE IN
THUNDERSTORM TIMING OVER THE INTERIOR MOUNTAINS IS LOW. CONSIDERING
ANY DAY DURING THIS PERIOD COULD BE THE DAY STORMS FORM...OPTED TO
INCREASE POPS OVER THE HIGHER PEAKS TO INCLUDE A SLIGHT CHANCE OF
STORMS EACH AFTERNOON.

TEMPERATURES THROUGH NEXT WEEK WILL REMAIN FAIRLY CONSISTENT WITH NO
STRONG OFFSHORE OR ONSHORE FLOW EXPECTED. HIGH TEMPERATURES ARE
EXPECTED TO REMAIN IN THE UPPER 90S AND LOWER 100S ACROSS THE
INTERIOR WITH 60S AND LOWER 70S NEAR THE COAST. LOW CLOUDS WILL ALSO
CONTINUE TO INFLUENCE COASTAL AREAS WITH PATCHY FOG EXPECTED. RPA

&&

.AVIATION...CIGS AND VSBYS WERE SLOW TO IMPROVE AT THE COSTAL TAF
SITES TODAY WITH KCEC AND KACV REPORTING LIFR CONDITIONS INTO THE
AFTERNOON HOURS. AS OF 22Z...VISIBLE SATELLITE IMAGERY SHOWED
STRATUS HUGGING THE IMMEDIATE COAST FROM VC KCEC DOWN TO KACV...AND
ALONG MUCH OF THE MENDOCINO COAST WITH CUMULUS BUILDING ACROSS
EASTERN TRINITY COUNTY. THE COASTAL SITES MAY SEE A FEW HOURS OF VFR
CONDITIONS THIS EVENING...BUT COASTAL CLOUDS/FOG SHOULD REDEVELOP
OVERNIGHT PRODUCING IFR TO LIFR CONDITIONS. VFR CONDITIONS WILL
PREVAIL ACROSS THE INTERIOR WITH MVFR CONDITIONS AND MOUNTAIN
OBSCURATIONS POSSIBLE NEAR ANY THUNDERSTORMS THAT DEVELOP OVER THE
HIGHER TERRAIN OF TRINITY COUNTY. STP

&&

.MARINE...A PERSISTENT PATTERN WITH HIGH PRESSURE OVER THE EASTERN
PACIFIC AND A THERMAL TROUGH OVER CENTRAL CALIFORNIA WILL LEAVE
MODERATE TO STRONG NORTHERLIES OVER THE COASTAL WATERS FOR THE NEXT
WEEK. THE STRONGEST WINDS WILL REMAIN IN THE OUTER WATERS WITH SEAS
BUILDING TO 8 TO 11 FEET THIS WEEKEND INTO NEXT WEEK. SHORT PERIOD
SEAS MAY BUILD TO ABOVE SMALL CRAFT CRITERIA IN PORTIONS OF THE
INNER WATERS LATE IN THE WEEKEND INTO EARLY NEXT WEEK BUT GENERALLY
SEAS WILL REMAIN BELOW SMALL CRAFT NEAR THE IMMEDIATE COASTLINE.
HAVE EXTENDED THE SMALL CRAFT FOR THE OUTER WATERS THROUGH TUESDAY
EVENING...ESSENTIALLY THE LENGTH OF THE FORECAST. OTHERWISE THE
FORECAST REMAINS THE SAME AND NO MAJOR CHANGES WERE MADE TO THE
FORECAST AT THIS TIME. RPA

&&

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

SMALL CRAFT ADVISORY UNTIL MIDNIGHT PDT TUESDAY NIGHT PZZ470-475.

&&

$$

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