Area Forecast Discussion
Issued by NWS Eureka, CA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
000
FXUS66 KEKA 192216
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
316 PM PDT TUE AUG 19 2014

.SYNOPSIS...AN UPPER LEVEL TROUGH WILL EXIT TO THE SOUTHEAST
TONIGHT REMOVING THE THREAT OF THUNDERSTORMS FOR THE REMAINDER
OF THE WEEK.

&&

.DISCUSSION...CUMULUS CONVECTION HAS BEEN DEVELOPING OVER THE
INTERIOR MOUNTAINS THIS AFTERNOON...MAINLY IN TRINITY COUNTY.
12Z SOUNDING FROM MFR INDICATED FAVORABLE CONVECTIVE PARAMETERS
FOR TSTMS TODAY...WITH PWAT NEAR 1 INCH...A LIFTED INDEX AROUND
-4.5C AND CAPE OF 1450J/KG. NAM12 CONTINUES TO INDICATE CONVECTIVE
PRECIP GENERATION AROUND THE HORN FROM 21Z-03Z WITH AMOUNTS AROUND
1/4 OF AN INCH. THESE VALUES MAY BE UNDERDONE AND ISOLATED HEAVIER
SHOWERS SEEM POSSIBLE THROUGH THE LATE AFTERNOON OR EARLY EVENING
HOURS AROUND THE HORN. MODEL CROSS SECTIONS DO INDICATE A MORE
STABLE MID LEVEL LAYER BUILDING INTO REGION THIS EVENING FROM THE
WEST...WITH LAPSE RATES NEAR 6.0C/KM VS 7.5C/KM YESTERDAY.
SUSTAINED CONVECTION WILL BE DIFFICULT TO ACHIEVE THIS EVENING AS
THIS MID LEVEL STABLE LAYER SPREADS INTO THE REGION FROM THE WEST.
STORMS OVER THE HIGHER TERRAIN OF TRINITY COUNTY THAT DO MANAGE TO
BUST THROUGH THIS AFTERNOON WILL STRUGGLE TO SURVIVE AND SHOULD
COLLAPSE QUICKLY.

DRIER AIR AS WELL AS HIGHER MID LEVEL STABILITY WILL BE OVER
THE AREA ON WED AS A RIDGE BUILDS OFFSHORE. DRY AND STABLE
CONDITIONS WILL LIKELY PERSIST THROUGH THU. THE STRATUS LAYER
SHOULD ERODE SOME ON WED THEN MORE ON THU. IT WILL BE DIFFICULT
FOR IT TO GO AWAY COMPLETELY AROUND EKA AND SOUTH OF THE CAPE.
THUS THE STRATUS FORECAST HAS BEEN BASED LARGELY ON CLIMATOLOGY
AND PERSISTENCE. THE GFS AND ECWMF INDICATE A VIGOROUS 500MB
TROUGH AND NWLY SPEED MAX DROPPING INTO THE PACIFIC NW ON FRIDAY.
THIS TROUGH LOOKS TOO DRY TO POSE A THREAT OF SHOWERS OR TSTMS. IT
SHOULD PRODUCE SOME COOLING AND PERHAPS BREAK UP OR LIFT OUT THE
MARINE LAYER CLOUDS.

THE MODELS INDICATE WEAK TROUGHINESS ALOFT PERSISTING OVER THE
AREA THIS WEEKEND. THIS TROUGH WILL LIKELY KEEP TEMPERATURES NEAR
SEASONAL NORMALS AS WELL AS DIURNAL STRATUS AT THE COAST. THE CHANCES
FOR ANY PRECIP WITH THIS TROUGH LOOKS FAIRLY LOW AND WILL NOT
MAKE ANY MAJOR ADJUSTMENTS TO THE FORECAST AT THIS TIME.

THE FORECAST BECOMES MORE SKETCHY EARLY TO MID NEXT WEEK. THE GFS
AND ECMWF DIVERGE ON HOW WARM IT WILL GET ACROSS THE INTERIOR.
OVERALL...DRY AND SEASONABLY WARM WEATHER CONDITIONS LOOK TO
PERSIST...WITH DIURNAL STRATUS MOST LIKELY HOLDING AT THE COAST.
FOR NOW WILL STAY CLOSE TO CLIMATOLOGY BUT EDGE TEMPERATURES UP A
FEW DEGREES.

&&

.AVIATION...HIGH PRESSURE HAS STARTED TO BUILD BACK INTO THE AREA
TODAY. THE MARINE LAYER IN THE NORTH IS A BIT SHALLOWER TODAY...WITH
PIREPS INDICATING TOPS AROUND 1200 FT THIS MORNING. IN THE SOUTH THE
MARINE LAYER WAS DEEPER WITH SOME STRATUS WORKING IT WAY UP FROM THE
SOUTH AND BRINGING LOW CIGS FOR A FEW HOURS AT KUKI. A THIN BAND OF
STRATUS REMAINS IN PLACE ALONG THE COAST THIS AFTERNOON. THIS IS
KEEP IFR TO LIFR IN MOST AREAS. KCEC AND KACV WILL LIKELY SEE SOME
BREAKS IN THE CLOUDS THIS AFTERNOON...ALTHOUGH IT WILL LIKELY CLOUD
BACK UP QUICKLY THIS EVENING. THIS AFTERNOON THERE IS SOME CU OVER
THE INLAND AREAS AND A FEW THUNDERSTORMS ARE POSSIBLE THIS
AFTERNOON. THESE SHOULD DISSIPATE BY SUNSET THIS EVENING. TONIGHT
EXPECT STRATUS WILL RETURN TO THE COASTAL AREAS. THE MARINE LAYER IS
EXPECTED TO REMAIN FAIRLY SHALLOW SO IT WILL NOT MAKE IT ALL THAT
FAR INLAND. IT IS POSSIBLE IT COULD MAKE IT INTO UKIAH
AGAIN...ALTHOUGH CONFIDENCE IS TOO LOW ON THIS TO ADD IT TO THE
FORECAST. MKK

&&

.MARINE...HIGH PRESSURE CONTINUES TO SLOW BUILD IN AND TIGHTEN THE
PRESSURE GRADIENT...HOWEVER WINDS AND SEAS HAVE BEEN SLOW TO RISE.
SEAS ARE CURRENTLY RUNNING ABOUT 5 TO 7 FT AT 8 SECONDS. THESE WILL
CONTINUE TO SLOWLY BUILD TONIGHT. WINDS NEAR THE COAST CONTINUE TO
BE OUT OF THE SOUTH AT 5 TO 10 KT EARLY THIS AFTERNOON. WITH THE
INCREASING NORTHERLY WINDS THIS AFTERNOON EXPECT THESE WILL BECOMING
NORTHWESTERLY AGAIN BY THIS EVENING. CONFIDENCE IS LOW ON THIS
HOWEVER DUE TO THESE FEATURES BEING TO SMALL FOR MODELS TO CAPTURE.
CONDITIONS WILL BE FAIRLY SIMILAR TOMORROW. THURSDAY WINDS WILL
BEGIN TO DIMINISH AS AN UPPER LEVEL TROUGH STARTS TO APPROACH THE
AREA. THIS BREAK...HOWEVER...IS SHORT LIVED WITH INCREASE WINDS ONCE
AGAIN FOR FRIDAY AND SATURDAY.

A S SWELL AT A 15 SECOND PERIOD WILL CONTINUE INTO MID-WEEK...WITH
ANOTHER BATCH AT AROUND 12 SECONDS LATER IN THE WEEK AND INTO THE
WEEKEND. LONGER PERIOD SWELL STARTING AT AROUND A 20 SECOND PERIOD
IS FORECAST TO ARRIVE FROM THE S-SW BY THE WEEKEND. MKK/SEC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...CA...NONE.

NORTHWEST CALIFORNIA COASTAL WATERS... SMALL CRAFT ADVISORY UNTIL
4 PM PDT SATURDAY PZZ450-455-470-475.

&&

$$

VISIT US AT HTTP://WWW.WEATHER.GOV/EUREKA

FOLLOW US ON FACEBOOK AND TWITTER AT:
HTTP://WWW.FACEBOOK.COM/NWSEUREKA
HTTP://WWW.TWITTER.COM/NWSEUREKA





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.