293 FXUS66 KEKA 211120 AFDEKA AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE EUREKA CA 420 AM PDT SUN JUL 21 2013 .SYNOPSIS...HOT TEMPERATURES WILL CONTINUE ACROSS INTERIOR NORTHWEST CALIFORNIA TODAY AND MONDAY AS HIGH PRESSURE REMAINS CENTERED OVER THE WEST COAST. A STRONG MARINE LAYER WILL PRODUCE A LOW OVERCAST AND FOG ALONG THE COAST WITH PERHAPS SOME CLEARING IN THE AFTERNOONS AND EARLY EVENINGS. && .DISCUSSION...ANOTHER HOT DAY CAN BE EXPECTED ACROSS THE INTERIOR AS UPPER RIDGING REMAINS IN PLACE OVER THE WEST COAST. 850 TEMPS WILL BE SIMILAR TO YESTERDAY...SO EXPECT MOST PLACED TO HAVE A VERY SIMILAR DAY TO YESTERDAY. A WEAKENING UPPER LOW WILL BEGIN TO SHIFT NORTH MONDAY INTO TUESDAY BRINGING COOLER AIR ALOFT AND SOUTHERLY FLOW TO THE REGION. THIS SHOULD ALLOW TEMPERATURES TO DECLINE ACROSS MENDOCINO COUNTY ON MONDAY AND THEN ACROSS THE ENTIRE INTERIOR ON TUESDAY. THIS LOW WILL ALSO BRING WITH IT INCREASING MID AND UPPER LEVEL INSTABILITY AND MOISTURE TO THE REGION. MODELS ARE HAVING A TOUGH TIME LATCHING ONTO THE EXACT LOCATION OF THE UPPER LEVEL ENERGY...BUT GENERALLY IT WILL BE SHIFTING THROUGH THE AREA DURING THE DAY TUESDAY LIKELY TRIGGERING STORMS OVER THE HIGHER TERRAIN DURING THE AFTERNOON. THE INCREASING INSTABILITY MONDAY NIGHT MAY ALLOW A STORM OR TWO TO FORM OVER COASTAL MENDOCINO COUNTY AND THEN SPREAD NORTH WITH TIME. THUS SLIGHT CHANCE POPS HAVE BEEN CONTINUED FOR MUCH OF THE COASTAL WATERS MONDAY NIGHT AND TUESDAY. INSTABILITY WILL INCREASE ON WEDNESDAY AS THE LOW SLOWLY SLIDES NORTHEAST AND ANOTHER INTENSIFICATION OF STORMS WILL LIKELY OCCUR WEDNESDAY AFTERNOON. SOME STORMS MAY LINGER OVERNIGHT TUESDAY NIGHT BUT WITH THE BEST LIFT SLIDING NORTH NOCTURNAL STORMS ARE LOOKING A LITTLE LESS LIKELY. GENERAL UPPER LEVEL RIDGING WILL REMAIN IN PLACE OVER THE WEST COAST INTO THE NEXT WEEKEND...HOWEVER BOTH THE ECMWF AND GFS INDICATE A PIECE OF THE UPPER LOW WILL BECOME TRAPPED WITHIN THE RIDGE OVER NORTHERN CALIFORNIA. THIS MAY ALLOW SOME CONVECTIVE DEVELOPMENT EACH AFTERNOON THURSDAY THROUGH SATURDAY AND SOME STORMS ARE NOT OUT OF THE QUESTION. HOWEVER WITH THE SMALL SCALE FEATURES CHANGING FROM RUN TO RUN HAVE KEPT POPS MOSTLY AROUND 10 PERCENT FOR PRIMARILY THE MOUNTAINOUS TERRAIN. AFTER THE BRIEF COOL DOWN TUESDAY AND WEDNESDAY TEMPERATURES SHOULD REBOUND ACROSS THE INTERIOR A FEW DEGREES THURSDAY INTO SATURDAY. NEAR THE COAST STRATUS WILL CONTINUE TO BE AN ISSUE EACH NIGHT AND MORNING WITH SOME CLEARING DURING THE AFTERNOON HOURS. SOUTHERLY FLOW ALONG THE MENDOCINO COAST BEGINNING MONDAY INTO TUESDAY MAY TRAP THE STRATUS NEAR THE COAST...HOWEVER INCREASING MIXING AS THE UPPER LOW ENERGY MOVES OVERHEAD MAY BE JUST ENOUGH TO DISSIPATE THE LOW LEVEL CLOUD COVER. CONFIDENCE IS DEFINITELY LOW ON WHAT THE STRATUS COVERAGE LOOKS LIKE EARLY THIS COMING WEEK. RPA && .AVIATION...VERY LITTLE CHANGE IN THE SYNOPTIC PATTERN SINCE YESTERDAY...SO FCST WILL BE PREDOMINANTLY BASED ON PERSISTENCE. IFR CONDITIONS WILL PREVAIL THROUGH THE MORNING ALONG THE COAST WITH VFR ACROSS THE INTERIOR. SLY WINDS ALONG THE REDWOOD COAST WILL MAKE IT DIFFICULT FOR STRATUS TO SCOUR OUT COMPLETELY...ALTHOUGH A FEW HRS OF SCT IS POSSIBLE AGAIN BETWEEN 22-03Z. && .MARINE...06Z ASCAT PASS SHOWED NLY WINDS 25-35KT OVER THE OFFSHORE WATERS AND BUOY OBS REPORT NNW SEAS 8-13 FT AT 8 TO 9 SECONDS. NLY GALES WILL PERSIST OVER THE OFFSHORE WATERS TODAY WITH STEEP SHORT PERIOD SEAS PROPAGATING THROUGH THE WATERS. AGAIN...WEIGHED ISSUING A HAZ SEAS WARNING FOR PZZ455...BUT HIGHEST SEAS WILL BE ACROSS WRN PORTIONS NEAR CAPE MENDO AND PT ARENA. THE PRESSURE GRADIENT WILL BEGIN TO EASE THIS EVENING AS THE THERMAL TROUGH ACROSS THE INTERIOR WEAKENS RESULTING IN IMPROVING CONDITIONS OVERNIGHT INTO MON. THE THERMAL TROUGH WILL STRENGTHEN AGAIN WED WITH INCREASING NLY WINDS AND SHORT PERIOD SEAS FOR THE LATTER HALF OF THE WEEK. && .FIRE WEATHER...HOT TEMPERATURES WITH LOW AFTERNOON RH WILL CONTINUE TODAY INTO MONDAY FOR INTERIOR AREAS. RECOVERIES WILL BE DECENT IN VALLEY LOCATIONS OVERNIGHT WITH POOR RECOVERIES IN THE MOUNTAINS. HOWEVER WINDS WILL REMAIN LIGHT AND NO CONCERNS ARE EXPECTED THROUGH MONDAY. BY MONDAY NIGHT A LOW WILL SLIDE NORTH ALONG THE COAST BRINGING INCREASING INSTABILITY AND MOISTURE TO THE REGION. ISOLATED TO SCATTERED THUNDERSTORMS ARE ANTICIPATED TO FORM...POSSIBLY STARTING NOCTURNALLY MONDAY NIGHT INTO TUESDAY...AND THEN INTENSIFYING BOTH TUESDAY AND WEDNESDAY AFTERNOONS. MODELS ARE STILL HAVING A TOUGH TIME LATCHING ONTO THE SMALL SCALE FEATURES BUT GENERALLY HAVE BEEN CONSISTENT WITH THE SYNOPTIC SCALE PATTERN. THUS CONFIDENCE IS MODERATE TO HIGH IN AT LEAST ISOLATED THUNDERSTORMS. STORMS WILL START OUT AS DRY AND THE TRANSITION TO WET BY TUESDAY EVENING AND WEDNESDAY AS PRECIPITABLE WATER INCREASES TO OVER 1 INCH. INVERTED-V PROFILES WILL ALSO BRING A THREAT OF GUSTY WINDS WITH ANY STORMS. A HEADLINE WILL BE ADDED INTO SEGMENTS OF THE FIRE WEATHER FORECAST TO HIGHLIGHT THE INCREASING LIGHTNING THREAT. THE NUMBER OF LIGHTNING STRIKES IS STILL IN QUESTION...BUT A WATCH WILL AT LEAST NEED TO BE CONSIDERED WITHIN THE NEXT FEW FORECAST CYCLES SHOULD INDICATIONS OF A WIDESPREAD LIGHTNING EVENT INCREASE. ADDITIONAL ISOLATED MOUNTAIN BASED STORMS WILL BE POSSIBLE THURSDAY INTO SATURDAY. RPA && .EKA WATCHES/WARNINGS/ADVISORIES... CA...NONE. NORTHWEST CALIFORNIA COASTAL WATERS... SMALL CRAFT ADVISORY UNTIL 9 AM PDT MONDAY PZZ450. GALE WARNING UNTIL 9 AM PDT MONDAY PZZ470. SMALL CRAFT ADVISORY UNTIL 3 PM PDT THIS AFTERNOON PZZ455. GALE WARNING UNTIL 9 PM PDT THIS EVENING PZZ475. && $$ VISIT US AT HTTP://WWW.WEATHER.GOV/EUREKA FOLLOW US ON FACEBOOK AND TWITTER AT: HTTP://WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.EUREKA.GOV HTTP://WWW.TWITTER.COM/NWSEUREKA