554 
FXUS66 KEKA 211250
AFDEKA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE EUREKA CA
550 AM PDT TUE APR 21 2015

.SYNOPSIS...AN UPPER TROUGH WILL BRING A SLIGHT THREAT
FOR THUNDERSTORMS TO THE INTERIOR TODAY. THE MARINE
LAYER WILL CONTINUE TO DEEPEN TODAY AND PUSH CLOUD LOW
COVER INLAND BY TONIGHT AS BREEZY NORTH WINDS DEVELOP
AT THE COAST.

&&

.DISCUSSION...THE MARINE LAYER WILL CONTINUE TO DEEPEN TODAY 
AS AN UPPER TROUGH APPROACHES THE COAST AND NORTHERLY 
FLOW INCREASES AT THE COAST. NAM12 PROFILES AND X-SECTIONS
INDICATE HIGH HUMIDITY PERSISTING EVEN AS NORTHERLY WINDS AND
MIXING INCREASES THIS AFTERNOON. SATELLITE IMAGERY DID SHOW A
CLEAR SLOT OFFSHORE THE OREGON COAST. THIS SHOULD ADVECT SOUTHWARD
BY THIS EVENING. HOWEVER NAM12 PROFILES SUGGESTS CLOUDS HANGING
AROUND INTO THE EVENING HOURS. CONFIDENCE IS NOT HIGH WE WILL
SEE COMPLETE CLEARING OF THE STRATUS CLOUDS THIS AFTERNOON INTO
THIS EVENING. BETTER DRYING IS EXPECTED ON WED AS NORTH WINDS
CRANK UP. WE SHOULD SEE MORE SUNSHINE ON WED...HOWEVER BLUSTERY
NORTH WINDS WILL MAKE IT FEEL CHILLY ALONG THE COAST.

CONVECTION WILL LIKELY DEVELOP ACROSS THE INTERIOR AGAIN TODAY.
NAM12 CONTINUES TO INDICATE UNBELIEVABLE INSTABILITY WITH MUCAPES
IN EXCESS OF 3000J/KG AND LIFTED INDICES AROUND -7C. GFS SURFACE
BASED CAPE LOOKED MORE REASONABLE WITH VALUES AROUND 500J/KG AND
LIFTED INDICES NEAR -3C. ISOLATED STORMS THAT SPROUTED UP WITH
DAYTIME HEATING YESTERDAY COLLAPSED VERY QUICKLY. THERE WILL BE
STRONGER 0-6KM BULK SHEAR TODAY...AROUND 20-25KT OVER THE HORN
AND YOLLA BOLLA MOUNTAINS. THE STORMS MAY BE SLIGHTLY STRONG WITH
LONGER LASTING UPDRAFTS TODAY...HOWEVER THE SW FLOW ALOFT WILL
ALSO SERVE TO PUSH THE STORMS OFF TO THE NE. IT IS STILL QUITE DRY
WITH PWATS AROUND 0.50IN AND 700-500MB HUMIDITY AROUND 40%. THUS
EXPECT VERY LITTLE OR NO PRECIP WITH THE STORMS. 

THE APPROACHING UPPER TROUGH WILL MOVE OVER THE REGION TONIGHT.
SHOWER ACTIVITY MAY DEVELOP PRIMARILY OVER THE HIGHER ELEVATIONS
TONIGHT AS THE TROUGH SHEARS APART. THE LOWER ATMOSPHERE WILL
COOL DOWN THROUGH THE NIGHT AS ROBUST ONSHORE FLOW DEVELOPS. THIS
LOW LEVEL COOLING WILL WEAKEN THE MARINE INVERSION AND ALLOW THE
COAST TO CLEAR OUT BY WED MORNING. THE MODELS CONTINUE TO SHOW
WEAK INSTABILITY AND CONVECTIVE PRECIP ACROSS INTERIOR MENDOCINO
COUNTY ON WED AS THE TROUGH ALOFT HEADS TO THE SOUTHEAST. I AM NOT
TOO CONFIDENT THERE WILL BE ANY STORM ACTIVITY AS NORTH-NORTHEAST
WINDS DEVELOP FROM THE SURFACE TO 500MB. THIS IS AN UNFAVORABLE
WIND DIRECTION FOR STORMS. THE NAM12 AND GFS DO SHOW CONVECTIVE
PRECIP DEVELOPING WITH DAYTIME HEATING...SO HAVE MAINTAINED A
SLIGHT CHANCE OF THUNDERSTORMS...MAINLY OVER THE HIGHER ELEVATIONS
IN EASTERN MENDOCINO COUNTY.

FLAT RIDGING WILL DEVELOP WED NIGHT INTO THU MORNING BEFORE
ANOTHER WEAK SHORT-WAVE TROUGH MOVES TOWARD THE AREA. THIS 
SHORT WAVE MAY GENERATE SOME SHOWER ACTIVITY OVER THE
MOUNTAINS...HOWEVER CONVECTIVE PARAMETERS ARE UNFAVORABLE FOR MORE
STORMS ON THU. IT WILL BE COOLER ACROSS THE ENTIRE AREA WITH THE
POSSIBILITY OF LATE NIGHT/EARLY MORNING PATCHY FROST IN SOME OF
THE INTERIOR VALLEYS.
 
DRY WEATHER IS EXPECTED ON FRI AS A BROAD RIDGE DEVELOPS BEHIND
THIS SHORT-WAVE. CONFIDENCE IN THE FORECAST FOR THE WEEKEND AND
EARLY NEXT WEEK IS LOW. THE MODELS DIVERGE SIGNIFICANTLY SAT
THROUGH TUE. THE ECMWF INDICATES OVER-RUNNING PRECIP ON SAT AND
SUN WITH DRY WEATHER ON MON AND TUE. THE GFS ON THE OTHER HAND IS
MOSTLY DRY WITH JUST LIGHT PRECIP OVER DEL NORTE COUNTY SAT AND
SUN...THEN WET ON MON AND TUE. YESTERDAY THE GFS WAS MUCH WETTER
AND FASTER THAN THE ECMWF AND HAD RAIN OVER THE AREA SAT NIGHT
AND SUN. ON MON AND TUE...THE GFS IS WET WHILE THE ECMWF DRY. WITH
THE MODELS FLIP FLOPPING AROUND FROM ONE RUN TO THE
NEXT...CONFIDENCE IN THE FORECAST IS LOW. THUS WILL MAKE NO
CHANGES AND LEAVE THE PRECIP CHANCES NEAR CLIMO.

&&

.AVIATION...CEILINGS HAVE RISEN SEVERAL HUNDRED FT OVERNIGHT ALONG 
THE REDWOOD COAST...BUT LOW CLOUDS REMAIN ENTRENCHED. THE AREAL 
EXTENT OF THE LOW CLOUDS IS DIFFICULT TO DISCERN ON SATELLITE PIX 
DUE TO HIGH CLOUDS. NAM KEEPS LOW CEILINGS AT KACV THRU THE DAY WITH 
SOME INDICATION OF PARTIAL CLEARING AT KCEC. LOW CLOUDS HAVE 
ADVECTED UP THE RUSSIAN VALLEY TO KUKI AS PREVIOUSLY FORECAST. THESE 
CLOUDS SHOULD BREAK UP LATER THIS MORNING. ISOLATED THUNDERSTORMS 
ARE POSSIBLE OVER THE YOLLA BOLLYS THIS AFTERNOON. HOWEVER...THESE 
ARE EXPECTED TO REMAIN NE OF KUKI. WINDS ARE EXPECTED TO BECOME 
GUSTY BY THIS AFTERNOON ACROSS THE AREA...WITH THE HIGHEST SURFACE 
GUSTS ALONG THE COAST. GUSTS OVER 30 KTS ARE POSSIBLE AT BOTH KACV 
AND KCEC. /SEC

&&

.MARINE...WINDS HAVE BEGUN TO INCREASE OVER THE COASTAL WATERS THIS 
MORNING...AND THIS WILL CONTINUE THRU TODAY AND TONIGHT AS THE 
PRESSURE GRADIENT TIGHTENS BETWEEN AN INLAND TROF AND PACIFIC HIGH 
PRESSURE. HAVE CONTINUED THE GALE WARNING FOR THE OFFSHORE WATERS 
FROM THIS AFTERNOON THRU THU EVENING. ALSO EXPANDED THE WARNING INTO 
THE N NEAR SHORE WATERS FROM THIS EVENING THRU WED NIGHT. WIND GUSTS 
IN THE OFFSHORE WATERS MAY APPROACH STORM FORCE TONIGHT...BUT THE 
AREAL COVERAGE...FREQUENCY...AND DURATION PRECLUDE ANY HEADLINE AT 
THIS TIME. WILL CONTINUE TO MONITOR CONDITIONS IN THE S NEAR SHORE 
WATERS FOR POSSIBLE HAZARDOUS SEAS WARNING...BUT AS OF NOW LOOKS TO 
BE JUST BELOW CRITERIA. WINDS ARE FORECAST TO MAX OUT EARLY WED 
MORNING...THEN GRADUALLY DIMINISH INTO THE WEEKEND. /SEC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR PZZ450.

     GALE WARNING FROM 9 PM THIS EVENING TO MIDNIGHT PDT WEDNESDAY 
     NIGHT FOR PZZ450.

     SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR 
     PZZ470-475.

     GALE WARNING FROM 3 PM THIS AFTERNOON TO 9 PM PDT THURSDAY FOR 
     PZZ470-475.

     SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 AM PDT FRIDAY 
     FOR PZZ455.

&&

$$

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

045 
FXUS66 KEKA 211250 CCA
AFDEKA

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE EUREKA CA
550 AM PDT TUE APR 21 2015

.SYNOPSIS...AN UPPER TROUGH WILL BRING A SLIGHT THREAT
FOR THUNDERSTORMS TO THE INTERIOR TODAY. THE MARINE
LAYER WILL CONTINUE TO DEEPEN TODAY AND PUSH LOW
COVER INLAND BY TONIGHT AS BREEZY NORTH WINDS 
DEVELOP AT THE COAST.

&&

.DISCUSSION...THE MARINE LAYER WILL CONTINUE TO DEEPEN TODAY 
AS AN UPPER TROUGH APPROACHES THE COAST AND NORTHERLY 
FLOW INCREASES AT THE COAST. NAM12 PROFILES AND X-SECTIONS
INDICATE HIGH HUMIDITY PERSISTING EVEN AS NORTHERLY WINDS AND
MIXING INCREASES THIS AFTERNOON. SATELLITE IMAGERY DID SHOW A
CLEAR SLOT OFFSHORE THE OREGON COAST. THIS SHOULD ADVECT SOUTHWARD
BY THIS EVENING. HOWEVER NAM12 PROFILES SUGGESTS CLOUDS HANGING
AROUND INTO THE EVENING HOURS. CONFIDENCE IS NOT HIGH WE WILL
SEE COMPLETE CLEARING OF THE STRATUS CLOUDS THIS AFTERNOON INTO
THIS EVENING. BETTER DRYING IS EXPECTED ON WED AS NORTH WINDS
CRANK UP. WE SHOULD SEE MORE SUNSHINE ON WED...HOWEVER BLUSTERY
NORTH WINDS WILL MAKE IT FEEL CHILLY ALONG THE COAST.

CONVECTION WILL LIKELY DEVELOP ACROSS THE INTERIOR AGAIN TODAY.
NAM12 CONTINUES TO INDICATE UNBELIEVABLE INSTABILITY WITH MUCAPES
IN EXCESS OF 3000J/KG AND LIFTED INDICES AROUND -7C. GFS SURFACE
BASED CAPE LOOKED MORE REASONABLE WITH VALUES AROUND 500J/KG AND
LIFTED INDICES NEAR -3C. ISOLATED STORMS THAT SPROUTED UP WITH
DAYTIME HEATING YESTERDAY COLLAPSED VERY QUICKLY. THERE WILL BE
STRONGER 0-6KM BULK SHEAR TODAY...AROUND 20-25KT OVER THE HORN
AND YOLLA BOLLA MOUNTAINS. THE STORMS MAY BE SLIGHTLY STRONGER
WITH LONGER LASTING UPDRAFTS TODAY...HOWEVER THE SW FLOW ALOFT
WILL ALSO SERVE TO PUSH THE STORMS OFF TO THE NE. IT IS STILL
QUITE DRY WITH PWATS AROUND 0.50IN AND 700-500MB HUMIDITY AROUND
40%. THUS EXPECT VERY LITTLE OR NO PRECIP WITH THE STORMS.

THE APPROACHING UPPER TROUGH WILL MOVE OVER THE REGION TONIGHT.
SHOWER ACTIVITY MAY DEVELOP PRIMARILY OVER THE HIGHER ELEVATIONS
TONIGHT AS THE TROUGH SHEARS APART. THE LOWER ATMOSPHERE WILL
COOL DOWN THROUGH THE NIGHT AS ROBUST ONSHORE FLOW DEVELOPS. THIS
LOW LEVEL COOLING WILL WEAKEN THE MARINE INVERSION AND ALLOW THE
COAST TO CLEAR OUT BY WED MORNING. THE MODELS CONTINUE TO SHOW
WEAK INSTABILITY AND CONVECTIVE PRECIP ACROSS INTERIOR MENDOCINO
COUNTY ON WED AS THE TROUGH ALOFT HEADS TO THE SOUTHEAST. I AM NOT
TOO CONFIDENT THERE WILL BE ANY STORM ACTIVITY AS NORTH-NORTHEAST
WINDS DEVELOP FROM THE SURFACE TO 500MB. THIS IS AN UNFAVORABLE
WIND DIRECTION FOR STORMS. THE NAM12 AND GFS DO SHOW CONVECTIVE
PRECIP DEVELOPING WITH DAYTIME HEATING...SO HAVE MAINTAINED A
SLIGHT CHANCE OF THUNDERSTORMS...MAINLY OVER THE HIGHER ELEVATIONS
IN EASTERN MENDOCINO COUNTY.

FLAT RIDGING WILL DEVELOP WED NIGHT INTO THU MORNING BEFORE
ANOTHER WEAK SHORT-WAVE TROUGH MOVES TOWARD THE AREA. THIS 
SHORT WAVE MAY GENERATE SOME SHOWER ACTIVITY OVER THE
MOUNTAINS...HOWEVER CONVECTIVE PARAMETERS ARE UNFAVORABLE FOR MORE
STORMS ON THU. IT WILL BE COOLER ACROSS THE ENTIRE AREA WITH THE
POSSIBILITY OF LATE NIGHT/EARLY MORNING PATCHY FROST IN SOME OF
THE INTERIOR VALLEYS.
 
DRY WEATHER IS EXPECTED ON FRI AS A BROAD RIDGE DEVELOPS BEHIND
THIS SHORT-WAVE. CONFIDENCE IN THE FORECAST FOR THE WEEKEND AND
EARLY NEXT WEEK IS LOW. THE MODELS DIVERGE SIGNIFICANTLY SAT
THROUGH TUE. THE ECMWF INDICATES OVER-RUNNING PRECIP ON SAT AND
SUN WITH DRY WEATHER ON MON AND TUE. THE GFS ON THE OTHER HAND IS
MOSTLY DRY WITH JUST LIGHT PRECIP OVER DEL NORTE COUNTY SAT AND
SUN...THEN WET ON MON AND TUE. YESTERDAY THE GFS WAS MUCH WETTER
AND FASTER THAN THE ECMWF AND HAD RAIN OVER THE AREA SAT NIGHT
AND SUN. ON MON AND TUE...THE GFS IS WET WHILE THE ECMWF DRY. WITH
THE MODELS FLIP FLOPPING AROUND FROM ONE RUN TO THE
NEXT...CONFIDENCE IN THE FORECAST IS LOW. THUS WILL MAKE NO
CHANGES AND LEAVE THE PRECIP CHANCES NEAR CLIMO.

&&

.AVIATION...CEILINGS HAVE RISEN SEVERAL HUNDRED FT OVERNIGHT ALONG 
THE REDWOOD COAST...BUT LOW CLOUDS REMAIN ENTRENCHED. THE AREAL 
EXTENT OF THE LOW CLOUDS IS DIFFICULT TO DISCERN ON SATELLITE PIX 
DUE TO HIGH CLOUDS. NAM KEEPS LOW CEILINGS AT KACV THRU THE DAY WITH 
SOME INDICATION OF PARTIAL CLEARING AT KCEC. LOW CLOUDS HAVE 
ADVECTED UP THE RUSSIAN VALLEY TO KUKI AS PREVIOUSLY FORECAST. THESE 
CLOUDS SHOULD BREAK UP LATER THIS MORNING. ISOLATED THUNDERSTORMS 
ARE POSSIBLE OVER THE YOLLA BOLLYS THIS AFTERNOON. HOWEVER...THESE 
ARE EXPECTED TO REMAIN NE OF KUKI. WINDS ARE EXPECTED TO BECOME 
GUSTY BY THIS AFTERNOON ACROSS THE AREA...WITH THE HIGHEST SURFACE 
GUSTS ALONG THE COAST. GUSTS OVER 30 KTS ARE POSSIBLE AT BOTH KACV 
AND KCEC. /SEC

&&

.MARINE...WINDS HAVE BEGUN TO INCREASE OVER THE COASTAL WATERS THIS 
MORNING...AND THIS WILL CONTINUE THRU TODAY AND TONIGHT AS THE 
PRESSURE GRADIENT TIGHTENS BETWEEN AN INLAND TROF AND PACIFIC HIGH 
PRESSURE. HAVE CONTINUED THE GALE WARNING FOR THE OFFSHORE WATERS 
FROM THIS AFTERNOON THRU THU EVENING. ALSO EXPANDED THE WARNING INTO 
THE N NEAR SHORE WATERS FROM THIS EVENING THRU WED NIGHT. WIND GUSTS 
IN THE OFFSHORE WATERS MAY APPROACH STORM FORCE TONIGHT...BUT THE 
AREAL COVERAGE...FREQUENCY...AND DURATION PRECLUDE ANY HEADLINE AT 
THIS TIME. WILL CONTINUE TO MONITOR CONDITIONS IN THE S NEAR SHORE 
WATERS FOR POSSIBLE HAZARDOUS SEAS WARNING...BUT AS OF NOW LOOKS TO 
BE JUST BELOW CRITERIA. WINDS ARE FORECAST TO MAX OUT EARLY WED 
MORNING...THEN GRADUALLY DIMINISH INTO THE WEEKEND. /SEC

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
NORTHWEST CALIFORNIA COASTAL WATERS...
     SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR PZZ450.

     GALE WARNING FROM 9 PM THIS EVENING TO MIDNIGHT PDT WEDNESDAY 
     NIGHT FOR PZZ450.

     SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON FOR 
     PZZ470-475.

     GALE WARNING FROM 3 PM THIS AFTERNOON TO 9 PM PDT THURSDAY FOR 
     PZZ470-475.

     SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 9 AM PDT FRIDAY 
     FOR PZZ455.

&&

$$

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