072  
FXUS66 KEKA 202238  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
338 PM PDT SUN AUG 20 2017  
   
SYNOPSIS
 
NORTHEASTERLY WINDS WILL CONTINUE TO TRANSPORT SMOKE  
ACROSS THE REDWOOD COAST THROUGH MONDAY. OTHERWISE, THUNDERSTORMS  
WILL BE POSSIBLE OVER PORTIONS OF TRINITY AND NORTHEASTERN  
MENDOCINO COUNTIES DURING THE AFTERNOON AND EVENING HOURS OF  
MONDAY, TUESDAY, AND WEDNESDAY.  
 

 
   
DISCUSSION
 
AN OFFSHORE DIRECTED SURFACE PRESSURE GRADIENT  
LOCATED OVER FAR NWRN CA IS FORECAST TO COMPLETELY DISSIPATE BY  
MONDAY AFTERNOON, WITH ONSHORE WINDS DEVELOPING IN ITS WAKE. THIS  
SHOULD AID IN GRADUALLY CUTTING OFF THE REDWOOD COAST FROM THE  
STEADY STREAM OF THICK INLAND WILDFIRE SMOKE SPREADING SSW FROM  
SISKIYOU, CURRY, AND FAR EASTERN DEL NORTE COUNTIES.  
 
OTHERWISE, A WEAK UPPER LOW IS EVOLVING OFFSHORE FROM SRN CA.  
MODEL GUIDANCE INDICATES THAT MOISTURE, ALONG WITH COOLER MIDLEVEL  
TEMPERATURES, WILL SPREAD NORTH-NORTHWEST FROM THE UPPER LOW  
THROUGH MIDWEEK. THIS WILL YIELD AN ENVIRONMENT FAVORABLE FOR  
ISOLATED THUNDERSTORMS OVER THE YOLLA BOLLY MOUNTAINS DURING  
MONDAY AFTERNOON. THEREAFTER, THUNDERSTORM COVERAGE WILL INCREASE  
TUESDAY AFTERNOON/EVENING FROM NORTHEASTERN MENDOCINO COUNTY  
NORTH ACROSS MUCH OF TRINITY COUNTY. THUNDERSTORM POTENTIAL WILL  
BECOME MORE MARGINAL DURING WEDNESDAY AS DRIER MIDLEVEL WESTERLIES  
SPREAD ACROSS THE REGION.  
 
AFTER WEDNESDAY, AN UPPER RIDGE IS FORECAST TO AMPLIFY OVER THE  
WRN CONUS, WHICH WILL FAVOR MODERATING TEMPERATURES ACROSS THE  
INTERIOR.  
 

 
   
AVIATION
 
WILDFIRE SMOKE CONTINUES TO WREAK HAVOC WITH THE  
COASTAL TERMINALS TODAY WITH PERSISTENT MVFR TO OCCASIONAL IFR  
CEILINGS AND VISIBILITIES DUE TO THIS SMOKE. THIS PATTERN WILL  
PERSIST TONIGHT AND INTO TOMORROW BEFORE A GRADUAL WIND SHIFT  
OCCURS THAT SHOULD HELP TO MITIGATE THE SMOKE COVERAGE ACROSS THE  
REGION.  
 
TONIGHT MARINE STRATUS SHOULD COME BACK TO KACV DROPPING  
CONDITIONS TO IFR SOMETIME AROUND MIDNIGHT OR POSSIBLY SOONER.  
WITH STRONG WINDS STILL AT KCEC AM NOT EXPECTING MUCH STRATUS TO  
MAKE IT INTO THE TERMINAL UNTIL EARLY IN THE MORNING HOWEVER IF  
WINDS CEASE A LITTLE EARLIER THAN EXPECTED THIS STRATUS MAY  
MATERIALIZE SOONER. EITHER WAY STRATUS/SMOKE SHOULD KEEP KACV AND  
KCEC IN AT LEAST MVFR CONDITIONS THROUGH TOMORROW WITH PERIODS OF  
IFR POSSIBLE. KUKI DID GET STRATUS AND FOG EARLY THIS MORNING AND  
WITH A SIMILARLY DEEP MARINE LAYER AND SOUTHERLY WINDS THIS  
POSSIBILITY COULD EXIST FOR TOMORROW MORNING AS WELL. IF THE  
STRATUS DOES MAKE IT IN TO KUKI I WOULD EXPECT IT TO BURN OFF BY  
LATE MORNING LEAVING THE TERMINAL IN VFR CONDITIONS FOR THE REST  
OF THE DAY. /WCI  
 

 
   
MARINE
 
GALE CONDITIONS WILL CONTINUE TO OCCUR ACROSS THE OUTER  
WATERS THROUGH TOMORROW MORNING. VERY LARGE AND STEEP SEAS WILL  
ALSO PERSIST THROUGH TOMORROW MORNING AND THEN GRADUALLY BEGIN TO  
DECREASE THROUGH THE EARLY PART OF THE WEEK. THE INNER WATERS WILL  
HAVE A SMALL CRAFT ADVISORY IN EFFECT THROUGH EARLY TOMORROW  
MORNING AS WELL FOR WINDS AND LARGE STEEP WAVES. IN ADDITION, A  
HAZARDOUS SEAS WARNING IS IN EFFECT FOR THE NORTHERN INNER WATERS  
TILL LATER TONIGHT FOR VERY LARGE AND STEEP SEAS. TOMORROW  
AFTERNOON CONDITIONS WILL IMPROVE FOR THE SOUTHERN INNER WATERS  
HOWEVER STRONG WINDS MAY STILL BE POSSIBLE NEAR CAPE MENDOCINO  
HOWEVER THE SPATIAL COVERAGE IS TOO SMALL TO CONTINUE TO THE SMALL  
CRAFT ADVISORY FOR THAT ZONE. BY LATE TUESDAY CONDITIONS ACROSS  
ALL MARINE ZONES WILL CALM WITH SMALLER SEAS AND WEAKER WINDS.  
CONDITIONS WILL START TO DETERIORATE YET AGAIN FRIDAY AND PERSIST  
THROUGH THE WEEKEND. /WCI  
 

 
   
FIRE WEATHER
 
OCCASIONAL GUSTS OUT OF THE NORTHEAST FROM 20-30  
MPH ARE FORECAST TO DIMINISH THIS EVENING. OTHERWISE,  
THUNDERSTORMS WILL BE POSSIBLE DURING THE AFTERNOON/EVENING HOURS  
OF MONDAY, TUESDAY, AND WEDNESDAY OVER PORTIONS OF TRINITY AND  
NORTHEASTERN MENDOCINO COUNTIES. SLOW STORM MOTIONS WILL FAVOR  
WETTING RAINFALL BENEATH INDIVIDUAL STORMS. HOWEVER, WARMER AND  
DRIER CONDITIONS DURING LATE WEEK COULD ALLOW HOLDOVER FIRES TO  
CONTINUE TO BURN AND EVENTUALLY STRENGTHEN.  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...NONE.  
NORTHWEST CALIFORNIA COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL  
11 AM PDT MONDAY FOR PZZ450.  
 
HAZARDOUS SEAS WARNING UNTIL 11 PM PDT THIS EVENING FOR PZZ450.  
 
GALE WARNING UNTIL 11 AM PDT MONDAY FOR PZZ470-475.  
 
SMALL CRAFT ADVISORY UNTIL 5 AM PDT MONDAY 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  
 
FOR FORECAST ZONE INFORMATION  
SEE THE FORECAST ZONE MAP ONLINE:  
HTTP://WWW.WEATHER.GOV/EUREKA/ZONEMAP.PNG  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab CA Page Main Text Page