Area Forecast Discussion
Issued by NWS Eureka, CA

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000
FXUS66 KEKA 292226
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
326 PM PDT TUE JUL 29 2014

.SYNOPSIS...COASTAL REGIONS WILL AGAIN BE SUBJECT TO FOG AND AREAS
OF DRIZZLE TONIGHT AND IN THE MORNING. INTERIOR LOCATIONS WILL SEE
AFTERNOON AND EVENING CLOUDS DISSIPATE OVER NIGHT BY MORNING. A
DISTURBANCE PASSING OVER THE REGION THIS AFTERNOON AND EVENING
WILL BRING A THREAT OF THUNDERSTORMS ACROSS MUCH OF THE NW
CALIFORNIA INTERIOR THIS AFTERNOON AND EARLY EVENING.

&&

.SHORT TERM (TODAY THROUGH WEDNESDAY)...COASTAL AREAS THIS EVENING
WILL SEE A REDEVELOPMENT OF THE LOW CLOUDS AND FOG ALONG WITH AREAS
OF DRIZZLE OVERNIGHT. AN APPROACHING WEAK UPPER LEVEL DISTURBANCE WILL
BRING MID AND UPPER LEVEL CLOUDS TO NW CAL CAUSING AT LEAST PARTLY
CLOUDY CONDITIONS OVER TO ALL AREAS TONIGHT. HAVE EXTENDED THE
COVERAGE OF ISOLATED THUNDERSTORMS OVER EASTERN PARTS OF TRINITY
COUNTY TIL NEAR MIDNIGHT. HOT TEMPS WILL CONTINUE INLAND THROUGH
THE END OF THE WEEK WHILE THE COAST REMAIN MODERATE.

SYNOPTICALLY SPEAKING; MONSOONAL MOISTURE CONTINUES TO BE PULLED
INTO CALIFORNIA AROUND THE WESTERN PERIPHERY OF THE FOUR CORNERS HIGH
OVER THE DESERT SOUTHWEST. THIS IS BEING JOINED TODAY BY A
VIGOROUS SHORTWAVE ROUNDING THE BOTTOM A BROAD UPPER LOW OVER THE
GULF OF ALASKA. WATER VAPOR SATELLITE IMAGES CONTINUE TO SHOW TWO
SHORTWAVES MOVING FROM THE SSW TO THE NNE, THE FIRST IS NOW NE OF
35N135W AND SHOULD ARRIVE OVER NW CALIFORNIA OVERNIGHT.

THE SECOND OF THESE SHORTWAVES SHOULD MOVE ACROSS NORTHERN CAL
AND INTO OREGON AT ABOUT THE TIME WHEN MONSOONAL MOISTURE
STREAMING NORTHWARD OF SOUTHERN CALIFORNIA REACHES THE AREA...DURING
PEAK HEATING OF THE DAY WEDNESDAY. THE SHORTWAVE AND DAYTIME HEATING SHOULD
PROVIDE ENOUGH INSTABILITY TO TRIGGER ISOLATED THUNDERSTORMS
ACROSS TRINITY, NE MENDOCINO, AND EASTERN DEL NORTE COUNTIES.
DAYTIME HEATING SHOULD BE PLENTY TO BLAST THROUGH THIS CAP. MKN

THURSDAY CONTINUES TO LOOK LIKE THE WEAKEST DAY FOR CONVECTION
OVER THE AREA, BUT FRIDAY WILL BRING YET ANOTHER THREAT OF
CONVECTION ACROSS THE NORTHEASTERN AREAS OF NW CAL. I WILL SAY THE
06Z GFS IS TRYING TO POP CONVECTION AGAIN ON THU, BUT NOT HOPING
ON BOARD QUITE YET. WILL WAIT FOR MORE MODEL CONSISTENCY. BFG ON
THU AND FRI...THE MODELS CONTINUE TO INDICATE NEBULOUS
SOUTHWESTERLY FLOW ALOFT WITH POORLY DEFINED AND HARD TO TIME
SHORT-WAVE FEATURES. CONVECTIVE PARAMETERS LOOK FAVORABLE FOR
AFTERNOON OR EARLY EVENING STORMS IN THE NORTHERN ZONES BOTH DAYS.
LAPSE RATE LOOK DECENT...BUT THERE WILL STILL BE A MID LEVEL
STABLE LAYER TO OVERCOME. WITHOUT THE MOISTURE AND EXTRA LIFT FROM
A SHORT-WAVE...IT WILL BE HARD FOR THE CONVECTION TO DEVELOPMENT
INTO DEEP STORMS. THUS FOR NOW WILL MAINTAIN A SLIGHT CHANCE OF
THUNDERSTORMS...MAINLY OVER THE HIGHER ELEVATIONS IN THE NORTHERN
ZONES...FORCED BY DAYTIME HEATING AND TERRAIN.

.LONG-RANGE (SAT THROUGH TUE)...GFS CONTINUES TO INDICATE FAVORABLE
CONVECTIVE PARAMETERS FOR STORMS OVER THE NORTHERN ZONES THROUGH THE
WEEKEND. BOTH THE ECMWF AND GFS HAVE AN UPPER TROUGH/LOW APPROACHING
THE COAST THIS WEEKEND. THE APPROACH OF THIS TROUGH SHOULD PRODUCE
BETTER SHEAR PROFILES FOR POSSIBLY MORE ORGANIZED AND SUSTAINED
CONVECTION. HOWEVER THERE IS VIRTUALLY NO COOLING ALOFT INDICATED IN
THE MODEL DATA. FOR NOW I WILL CONTINUE WITH JUST A SLIGHT CHANCE OF
THUNDERSTORMS ON SAT AND SUN IN THE NORTHERN INTERIOR ZONES. ON MON
AND TUE...THE GFS AND ECWMF TRY TO PUSH THE UPPER TROUGH THROUGH THE
FORECAST AREA...WITH WESTERLY FLOW ALOFT BRINGING DRIER AIR INTO THE
REGION. THE ECMWF WAS SLOWER WITH THIS TRANSITION. THE GFS DOES SHOW
INSTABILITY...MAINLY IN EASTERN TRINITY COUNTY ON MON AND TUE...SO
WILL MAINTAIN THE SLIGHT CHANCE OF TSTMS. THE FORECAST ALONG THE
COAST HAS BEEN BASED LARGELY ON CLIMATOLOGY AND PERSISTENCE.

&&

.MARINE....HIGH PRESSURE OFFSHORE COUPLED WITH A THERMAL TROUGH
OVER THE NORCAL INTERIOR WILL MAINTAIN MODERATE NORTHERLY WINDS
ACROSS THE OUTER WATERS THROUGH THE WEEK. THE NORTHERLY WINDS WILL
CONTINUE TO PRODUCE SHORT PERIOD NORTHERLY WAVES THROUGH THE WEEK
WHICH WILL PROPAGATE INTO THE INNER WATERS AS A SHORT PERIOD SWELL.
ADVISORIES IN THE OUTER WATERS HAVE BEEN MAINTAINED FOR STEEP SEAS
OF 7-9 FT AT 8 SECONDS AND WINDS OF 20-25 KT. NORTHERLIES MAY REACH
GALE FORCE WITH SEAS UP TO 13 FT LATE IN THE WEEK INTO THE WEEKEND.
THE POSSIBILITY FOR LOW END GALES HAS BEEN HIGHLIGHTED IN THE MWW.

&&

.AVIATION...LIFR CIGS HUGGING THE COAST AT 3PM WHILE TOWERING CU
DEVELOPING OVER SOUTH FORK RIDGE LINE AND FURTHER EAST. EXPECT
STRATUS TO PUSH BACK INLAND UP EEL RIVER VALLEY PUSHING PAST KFOT
AFTER 2200 PDT WITH WITH VSBYS ALSO BECOMING TO IFR. A SHORT WAVE OFF
THE COAST WILL BE GRAZING THE AREA AND THIS SHOULD BE ENOUGH TO
CONTINUE ISOLD CBS AND TSTMS TILL ABOUT MIDNIGHT IN EASTERN TRINITY
COUNTY. DEAN

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 5 PM PDT SUNDAY PZZ470-475.

&&

$$

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