752  
FXUS66 KEKA 122022  
AFDEKA  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE EUREKA CA  
122 PM PDT SUN JUL 12 2026  
   
KEY MESSAGES
 
 
* INTERIOR HEAT: AN UPPER-LEVEL RIDGE HAS MOVED WESTWARD CAUSING  
TEMPERATURES TO RISE ABOVE NORMAL ACROSS INLAND VALLEYS INTO EARLY  
NEXT WEEK.  
 
* SLIGHT THREAT FOR ISOLATED SHOWERS/THUNDERSTORMS. A 10 TO 20%  
CHANCE FOR THUNDERSTORMS MONDAY AND TUESDAY. THE HIGHEST CHANCES  
ARE IN TRINITY COUNTY ON TUESDAY AFTERNOON.  
 
* COASTAL FLOODING: MINOR COASTAL FLOODING AROUND HUMBOLDT BAY  
POSSIBLE AT THE EVENING HIGH TIDE TONIGHT THROUGH TUESDAY NIGHT.  
 

 
   
SYNOPSIS
 
HOT TEMPERATURES RETURN TO MUCH OF THE INTERIOR TODAY.  
MONSOONAL MOISTURE WILL BRING CLOUD COVER AND MOISTURE MONDAY AND  
TUESDAY. ISOLATED THUNDERSTORMS OR SHOWERS ARE POSSIBLE MONDAY AND  
TUESDAY IN THE INTERIOR.  
 

 
   
DISCUSSION
 
AN UPPER LEVEL TROUGH IN BRITISH COLUMBIA CONTINUES TO  
INCH EASTWARD WHILE AN UPPER RIDGE OVER THE SOUTHWEST US CONTINUES  
TO EXPAND WESTWARD. THIS RIDGE WILL BRING ABOVE NORMAL TEMPERATURES  
TO THE INTERIOR WITH 90S LIKELY FOR MOST VALLEYS AND THE WARMEST  
AREAS POSSIBLE EXCEEDING 100. MONSOONAL MOISTURE FROM THE SOUTH HAS  
STARTED TO STREAM OVER THE AREA IN THE FORM OF HIGH CLOUDS. SO FAR,  
NONE OF THESE HAVE RESULTED IN SHOWERS THAT REACHED THE GROUND. THIS  
MAY CHANGE OVERNIGHT AS ADDITIONAL MOISTURE STREAMS IN EARLY MONDAY  
MORNING. CAMS ARE SHOWING A HIGHER POTENTIAL FOR A FEW RAIN SHOWERS,  
ESPECIALLY IN MENDOCINO, LAKE, AND TRINITY COUNTIES. INSTABILITY IS  
LIMITED, BUT AN ISOLATED THUNDERSTORMS IS POSSIBLE WITH AN  
ESPECIALLY STRONG SHOWER. DRY SURFACE CONDITIONS WILL LIKELY PREVENT  
MOST PRECIPITATION FROM REACHING THE GROUND. THIS PATTERN CONTINUES  
MONDAY AFTERNOON AND OVERNIGHT THROUGH TUESDAY MORNING. INSTABILITY  
STILL REMAINS LIMITED, BUT A STRAY THUNDERSTORM CANNOT BE RULED OUT.  
THUNDER CHANCES INCREASE TUESDAY AFTERNOON WITH ADDED SURFACE  
HEATING. THE HIGHEST CHANCES ARE IN TRINITY COUNTY WITH UP TO 20%  
CHANCE FOR THUNDERSTORMS, THOUGH CAMS WITHIN RANGE SHOW CONVECTION  
BOTH FARTHER WEST AND FARTHER EAST.  
 
HIGH TEMPERATURES ARE FORECAST TO REMAIN IN THE 90S FOR MOST  
INTERIOR VALLEYS WITH THE WARMEST AREAS EXCEEDING 100 EARLY NEXT  
WEEK. ADDITIONAL CLOUD COVER EARLY NEXT WEEK MAY NUDGE THESE  
FORECASTED TEMPERATURES DOWN A FEW DEGREES. HEATRISK REMAINS MINOR  
TO LOCALLY MODERATE. COASTAL AREAS REMAIN IN THE HIGH 50S TO MID 60S  
WITH STRATUS FORMING OVERNIGHT AND PARTIALLY CLEARING BY THE  
AFTERNOON. DRIER AIR RETURNS MIDWEEK AS THE PACIFIC NORTHWEST TROUGH  
MOVES SOUTHWESTWARD. A DEEPER MARINE LAYER WILL LIKELY BRING  
INTERIOR TEMPERATURES DOWN BY A FEW DEGREES, WHILE BRINGING MORE  
WIDESPREAD, AND POSSIBLY PERSISTENT, COASTAL STRATUS. HIGH PRESSURE  
RETURNS LATE NEXT WEEK, RETURNING WARMER INTERIOR TEMPERATURES. /JB  
 

 
   
AVIATION...(18Z TAFS)
 
COASTAL STRATUS REMAINS OFF THE HUMBOLDT  
AND DEL NORTE COASTS EARLY THIS AFTERNOON, BUT HAS RETREATED  
OFFSHORE. SOME PERIODIC STRATUS IMPACTS ARE POSSIBLE INTO THE  
AFTERNOON AS THE STRATUS DISPERSES. BREEZY NORTHERLY WINDS ARE  
LIKELY ACROSS THE AREA IN THE AFTERNOON, ESPECIALLY ALONG THE COAST.  
STRATUS IS LIKELY TO RETURN AGAIN TONIGHT WITH A SOUTHERLY RETURN  
FLOW LIKELY TO ADVECT STRATUS NORTHWARD FROM HUMBOLDT BAY TO CEC.  
LIFR TO IFR CEILING IMPACTS ARE LIKELY SHOULD STRATUS DEVELOP WITH  
VISIBILITY REDUCTIONS POSSIBLE AROUND SUNRISE. STRATUS WILL LIKELY  
LIFT AND SCATTER SHORTLY AFTER SUNRISE. VFR CONDITIONS ARE LIKELY  
FOR THE INTERIOR AREAS FOR THE NEXT 24 HOURS. THERE IS A SMALL  
CHANCE FOR THUNDERSTORMS (10%) FOR MUCH OF THE INTERIOR AREA  
OVERNIGHT AND INTO MONDAY. /JB  
 

 
   
MARINE
 
NORTHERLY WINDS PEAK THIS EVENING WITH LOCALIZED GALE  
FORCE GUSTS IN THE LEE OF CAPE MENDOCINO AND SUSTAINED WINDS OF 20-  
25 KTS IN THE OUTER WATERS. NEARSHORE WINDS WILL BE MUCH LIGHTER AT  
10-20 KTS, BUT COULD STILL BE BREEZY THIS AFTERNOON. NORTHERLY WINDS  
EASE SOMEWHAT MONDAY INTO TUESDAY, BUT WILL REMAIN STRONG IN THE LEE  
OF CAPE MENDOCINO. STRONG WINDS AND STEEP SEAS RETURN MID TO LATE  
NEXT WEEK. SEAS WILL BE DOMINATED BY WIND WAVES AND A SHORT PERIOD  
NORTHWEST SWELL. STEEP WIND WAVES MAY PROPAGATE TO THE INNER WATERS  
EVEN AS WINDS REMAIN MILDER. /JB  
 

 
   
FIRE WEATHER
 
MONSOONAL MOISTURE HAS ARRIVED TO THE AREA AND WILL  
PEAK MONDAY AND TUESDAY. THERE IS HIGH UNCERTAINTY IF THIS WILL LEAD  
TO THUNDERSTORMS AS INSTABILITY IS LOW, BUT WITH WARM AND DRY LOW  
LEVELS, ANY THUNDER IS LIKELY TO BE DRY. SOME CAM RUNS ARE SHOWING  
SOME POTENTIAL FOR CONVECTION STARTING EARLY MONDAY MORNING AND  
AFTERNOON AND AGAIN MONDAY NIGHT INTO TUESDAY MORNING. THESE PULSES  
WILL START IN THE SOUTH AND MOVE NORTHWARD. MOST MODELS SHOW THIS  
FEATURE, BUT INSTABILITY IS MUCH WEAKER. THUS THERE ARE SEVERAL  
SLIGHT CHANCE OPPORTUNITIES FOR A FEW ISOLATED STORMS OVER THE AREA.  
THE HIGHEST CHANCE FOR THUNDERSTORMS REMAINS ON TUESDAY AFTERNOON  
WHEN THE HEATING OF THE DAY INCREASES THUNDERSTORMS CHANCES TO  
AROUND 10-20% IN TRINITY COUNTY AND INTO THE YOLLA BOLLYS. THIS MAY  
STILL NUDGE WESTWARD AND SOUTHWARD, BUT IS HIGHLY DEPENDENT ON HOW  
FAR EAST THE MOISTURE NUDGES. SOME MODELS DO SHOW MOISTURE  
COMPLETELY TO THE EAST OF THE AREA, STILL, SO CONFIDENCE GENERALLY  
REMAINS LOW. /JB/RPA  
 

 
   
COASTAL FLOODING
 
HIGH ASTRONOMICAL TIDES MAY LEAD TO MINOR  
COASTAL FLOODING AT THE EVENING HIGH TIDE EACH EVENING THROUGH  
TUESDAY EVENING. MINOR FLOODING OCCURS WHEN THE NORTH SPIT TIDE  
GAUGE REACHES 8.8 FT MLLW. THE ASTRONOMICAL TIDE IS FORECAST TO BE  
8.22 FT TONIGHT, 8.32 FT MONDAY NIGHT, AND 8.23 FT TUESDAY NIGHT.  
WITH AN ANOMALY OF 0.5-0.6 FT, THE TIDE MAY EXCEED 8.8 FT, WHICH  
WOULD COULD BRING MINOR FLOODING IMPACTS TO KING SALMON AND JACKSON  
RANCH ROAD IN THE ARCATA BOTTOMS. /JB  
 

 
   
EKA WATCHES/WARNINGS/ADVISORIES
 
 
CA...  
COASTAL FLOOD ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT  
PDT TONIGHT FOR CAZ103.  
 
NORTHWEST CALIFORNIA COASTAL WATERS...  
COASTAL FLOOD ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT  
PDT TONIGHT FOR PZZ415.  
 
SMALL CRAFT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR PZZ455.  
 
SMALL CRAFT ADVISORY UNTIL 11 PM PDT MONDAY FOR PZZ470.  
 
SMALL CRAFT ADVISORY UNTIL 3 AM PDT WEDNESDAY FOR PZZ475.  
 

 
 

 
 
NOTE: THE FULL FORECAST DISCUSSION IS NOW REGULARLY ISSUED BETWEEN  
10 AM/PM AND 1 PM/AM. ADDITIONAL UPDATES WILL BE ISSUED AS NEEDED.  
 
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