972  
FXUS66 KMFR 200330  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
830 PM PDT SAT AUG 19 2017  
   
DISCUSSION
 
THE MAIN FORECAST IMPACTS FOR TONIGHT WILL BE  
WILDFIRE SMOKE/AIR QUALITY AND ALSO THE OFFSHORE NORTHEAST WINDS  
EXPECTED ACROSS THE COAST RANGE IN SW OREGON/PORTIONS OF WESTERN  
SISKIYOU COUNTY.  
 
ONCE AGAIN, LOW-LEVEL UP VALLEY FLOW KICKED IN HERE IN THE ROGUE  
VALLEY LATE THIS AFTERNOON/EVENING. THIS WAS ABLE TO INCREASE  
VISIBILITY SOMEWHAT. BUT, IN CONTRAST TO LAST NIGHT, THE WINDS  
JUST WEREN'T ENOUGH TO SCOUR OUT THE SMOKE COMPLETELY. THIS IS  
DUE TO THE FACT THAT THE FIRES BURNING TO THE NORTH/NORTHEAST OF  
THE AREA GENERATED A LOT OF NEW SMOKE TODAY AND THE WINDS ALOFT  
WERE MORE OUT OF THE NORTH/NORTHEAST, RATHER THAN NORTH/NORTHWEST  
LIKE THEY WERE YESTERDAY. AN AIR QUALITY ALERT REMAINS IN EFFECT  
THROUGH SUNDAY AND THIS WILL BE RE-EVALUATED SUNDAY MORNING FOR  
POSSIBLE EXTENTION.  
 
OFFSHORE FLOW WILL PEAK TONIGHT, THEN SHOULD EASE SUNDAY NIGHT  
INTO MONDAY AS THE THERMAL TROUGH PUSHES INLAND. A RED FLAG  
WARNING IS OUT FOR TONIGHT INTO SUNDAY MORNING FOR FIRE ZONES  
618/619. PLEASE SEE FIRE WEATHER DISCUSSION BELOW FOR DETAILS.  
 
MONDAY MORNING ECLIPSE VIEWING WILL COME DOWN TO THICKNESS OF  
WILDFIRE SMOKE AND ALSO THE MARINE LAYER ALONG THE COAST. EXPECT  
SOME LOW STRATUS INITIALLY ALONG THE IMMEDIATE COAST AS THE FLOW  
BEGINS TO TURN ONSHORE. INLAND AREAS WILL BE CLEAR, BUT THE  
WILDFIRE SMOKE IS THE WILD CARD. EXPECT SMOKE TO BE A POTENTIAL  
ISSUE ALONG AND EAST OF A LINE FROM BROOKINGS TO ROSEBURG WITH THE  
THICKEST SMOKE FROM WESTERN SISKIYOU COUNTY UP THE CASCADES.  
SMOKE SHOULD ALSO BE THINNER THE FARTHER SOUTHEAST YOU GO ACROSS  
THE CWA, ESPECIALLY OVER TOWARD ALTURAS/LAKEVIEW.  
 
CONFIDENCE CONTINUES TO GROW THAT MOISTURE AND INSTABILITY WILL  
INCREASE ACROSS THE AREA TUESDAY INTO WEDNESDAY. THIS WILL BRING  
A RENEWED THREAT OF SIGNIFICANT LIGHTNING, ESPECIALLY FROM THE  
SISKIYOUS/CASCADES EASTWARD. STAY TUNED FOR DETAILS. -SPILDE  
 

 
   
AVIATION...20/00Z TAF CYCLE
 
GUSTY NORTH WINDS WILL CONTINUE ALONG  
THE COAST AND IN THE COASTAL MOUNTAINS THROUGH TONIGHT AND SUNDAY  
MORNING AS THE THERMAL TROUGH CONTINUES. THIS WILL AFFECT OTH UNTIL  
LATE THIS EVENING OR EVEN THROUGH MIDNIGHT. IFR AND LIFR CIGS WILL  
THEN RETURN TO THE COAST, NORTH OF CAPE BLANCO. EXPECT SIMILAR  
INCREASE IN WIND SPEED AT OTH AGAIN SUNDAY AFTERNOON WITH WIND GUST  
UP TO 35 KNOTS. NORTH WINDS ARE ALSO SURFACING DOWN TO RBG WITH GUST  
TO 25 KNOTS THROUGH LATE THIS EVENING.  
 
SATELLITE IMAGERY SHOWS WIDESPREAD SMOKE LAYER IN EASTERN DOUGLAS  
COUNTY (I-5 EAST) AND FROM GRANTS PASS EAST TO COVER JUST ABOUT ALL  
OF JACKSON COUNTY AND WESTERN KLAMATH COUNTY. THIS HAS BROUGHT  
VISIBILITY DOWN TO MVFR. WITH LESS WINDS AT MFR THIS EVENING,  
VISIBILITY COULD LOWER FURTHER TO IFR AFTER SUNSET AND REMAIN IFR  
OVERNIGHT. SATELLITE IMAGERY ALSO SHOW WIDESPREAD SMOKE IN SISKIYOU  
AND MODOC COUNTIES AND VISIBILITIES THERE ARE EXPECTED TO LOWER TO  
IFR OVERNIGHT AS WELL, ESPECIALLY IN VALLEY LOCATIONS. /FB  
 

 
   
MARINE...UPDATED 200 PM PDT SATURDAY 19 AUGUST 2017
 
THERE  
WILL BE LITTLE CHANGE IN THE OVERALL PATTERN THROUGH SUNDAY NIGHT.  
HIGH PRESSURE OFFSHORE AND A THERMAL TROUGH ALONG THE COAST WILL  
GENERATE MODERATE TO STRONG NORTH WINDS AND VERY STEEP SEAS THROUGH  
THIS WEEKEND. CONDITIONS WILL AT LEAST BE HAZARDOUS TO SMALL CRAFT  
OVER ALL OF THE FORECAST AREA, AND WARNING LEVEL WINDS/SEAS WILL  
OCCUR BEYOND 5 NM FROM SHORE FROM GOLD BEACH SOUTH. WINDS AND SEAS  
WILL BE HIGHEST DURING THE AFTERNOONS AND EVENINGS EACH DAY THROUGH  
SUNDAY, EASING A BIT DURING THE OVERNIGHT AND EARLY MORNING HOURS.  
THE THERMAL TROUGH WILL WEAKEN EARLY NEXT WEEK, AND WINDS WILL  
DIMINISH BUT SEAS ARE EXPECTED TO REMAIN STEEP THROUGH THE MIDDLE OF  
NEXT WEEK DUE TO SHORT PERIOD SWELLS. /FB  
 

 
   
FIRE WEATHER...UPDATED 345 PM SATURDAY, 19 AUGUST 2017
 
 
HIGH PRESSURE OFFSHORE AND A STRENGTHENING THERMAL TROUGH OVER  
CALIFORNIA WILL PRODUCE GUSTY NORTHWEST THROUGH NORTHEAST WINDS  
ACROSS MUCH OF THE AREA THIS AFTERNOON INTO TONIGHT. NORTHWEST WINDS  
WILL PEAK OVER THE WEST SIDE INLAND FROM THE COAST RANGE THIS  
AFTERNOON AND EVENING, WHILE NORTHWEST THROUGH NORTHEAST WINDS WILL  
PEAK EAST OF THE CASCADES THIS EVENING THROUGH SUNDAY MORNING. ALONG  
THE COAST RANGE WESTWARD WINDS WILL PEAK THIS EVENING AT SOME  
LOCATIONS, AND THE OVERNIGHT INTO THE MORNING ACROSS THE COAST  
RANGE. CONDITIONS WILL BE MOST CRITICAL IN THE FAR SOUTHWESTERN  
OREGON COASTAL MOUNTAINS AS GUSTY NORTHEAST WINDS CONTINUE THROUGH  
SUNDAY MORNING. WINDS WILL WEAKEN SOME SUNDAY INTO EARLY MONDAY, BUT  
RH RECOVERIES WILL STILL BE MODERATE TO POOR ON THE UPPER SLOPES AND  
RIDGES.  
 
LOWER ELEVATION WEST SIDE LOCATIONS WILL CONTINUE TO EXPERIENCE MID  
LEVEL HAINES 5 CONDITIONS THROUGH MONDAY WHERE THE INVERSION BREAKS,  
WHILE HIGHER ELEVATIONS EXPERIENCE MOSTLY HAINES 4 TO 5 WHERE THE  
INVERSION BREAKS.  
 
THE FLOW ALOFT WEAKENS AND SHIFTS TO SOUTHERLY MONDAY AS MOISTURE  
AND, THEN, INSTABILITY ARRIVE. THUNDERSTORMS WILL BE POSSIBLE  
TUESDAY AND WEDNESDAY FROM APPROXIMATELY THE CASCADES AND SISKIYOUS  
SOUTH AND EASTWARD. TUESDAY EVENING THROUGH WEDNESDAY MORNING SOME  
GUIDANCE IS INDICATING SOME POSSIBILITY OF THUNDERSTORMS CRESTING  
THE SISKIYOUS AND WEST OF THE CASCADES, SO WE'LL CONTINUE TO KEEP AN  
EYE ON THIS. WEDNESDAY AFTERNOON AND EVENING THE THREAT BEGINS TO  
KICK OUT TO THE EAST AND IS JUST ABOUT OUT OF THE AREA THURSDAY  
AFTERNOON AND EVENING. BTL  
 

 
   
PREV DISCUSSION
 
/ISSUED 400 PM PDT SAT AUG 19 2017/  
 
SHORT TERM...THE UPPER LEVEL RIDGE WILL REMAIN CENTERED OFFSHORE  
THROUGH SUNDAY WITH A SURFACE THERMAL TROUGH ALONG THE COAST. THE  
RIDGE WILL SHIFT INLAND OVER THE REGION ON MONDAY AND THE THERMAL  
TROUGH WILL MOVE INLAND MONDAY AFTERNOON. ALTHOUGH THERE WILL BE  
SOME WEAK UPPER LEVEL DISTURBANCES IN THE FLOW, EXPECT LITTLE  
IMPACT AND THE AREA WILL SEE CONTINUED VERY WARM AND DRY WEATHER  
THROUGH MONDAY.  
 
THE THERMAL TROUGH PATTERN IS BRINGING GUSTY NORTH TO NORTHEAST  
FLOW WEST OF THE CASCADES WITH STRONGEST WINDS OVER THE COASTAL  
MOUNTAINS. THESE COMBINED WITH LOW HUMIDITIES ARE RESULTING IN  
CRITICAL FIRE WEATHER CONDITIONS AND ACTIVE BURNING ON AREA FIRES.  
A RED FLAG WARNING IS IN EFFECT FOR MUCH OF CURRY COUNTY. SEE THE  
RFWMFR FOR DETAILS.  
 
SMOKE FROM AREA FIRES WILL CONTINUE ACROSS SOUTHWEST OREGON AND  
NORTHERN CALIFORNIA THROUGH EARLY NEXT WEEK. SIGNIFICANT AREAS OF  
SMOKE ARE EXPECTED OVER PORTIONS OF CURRY, DOUGLAS, JOSEPHINE,  
JACKSON, AND KLAMATH COUNTIES. THIS IS CREATING AIR QUALITY AND  
AIR QUALITY ALERTS ARE IN EFFECT THESE AREAS IN SOUTHWEST OREGON.  
AREAS OF SMOKE ARE ALSO PRESENT ACROSS PORTIONS OF NORTHERN  
CALIFORNIA ESPECIALLY IN SISKIYOU COUNTY. SMOKE IS EXPECTED TO BE  
LEAST ALONG THE COAST FROM GOLD BEACH NORTH AND OVER COOS AND  
NORTHWEST DOUGLAS COUNTY.  
 
TEMPERATURES OVER THE NEXT TWO DAYS WILL BE VERY WARM WITH HIGHS  
IN THE MID TO UPPER 90S FOR WESTERN VALLEYS AND IN THE UPPER 80S  
TO LOW 90S. AREAS ALONG THE COAST AND INLAND VALLEYS WEST OF THE  
CASCADES WILL EXPERIENCE BREEZY TO GUSTY NORTHERLY WINDS IN THE  
LATE AFTERNOON AND EVENING TODAY AND SUNDAY.  
 
ON MONDAY, THE DRY AND WARM WEATHER WILL CONTINUE ACROSS THE AREA  
WITH A RIDGE MOVING INLAND. GUSTY EASTERLY WINDS OVER THE RIDGES  
WILL DECREASE BY LATE MORNING. WINDS ALOFT OVER SOUTHERN PORTIONS  
OF THE AREA FROM AROUND THE SISKIYOUS SOUTH, WILL GRADUALLY  
CHANGE TO A SOUTHEAST DIRECTION LATE MONDAY MORNING. AS THE  
THERMAL TROUGH MOVES INLAND THOUGH, EXPECT WINDS TO SHIFT TO A  
NORTH TO NORTHWEST DIRECTION MONDAY AFTERNOON. SMOKE WILL CONTINUE  
TO BE A CONCERN FOR AREAS IN SOUTHWEST OREGON AND NORTHWEST  
CALIFORNIA BUT THE AREAS WHICH SEE THE WORST CONDITIONS MAY  
FLUCTUATE SLIGHTLY.  
 
CLOUD COVER IS EXPECTED TO BE CLEAR FOR MOSTLY CLEAR FOR MOST  
INLAND AREAS ON MONDAY, THE DAY OF THE ECLIPSE. SMOKE WILL REMAIN  
THE MAIN CONCERN FOR INLAND LOCATIONS. ALSO MODELS ARE SHOWING  
SOME LOW CLOUDS AND FOG ALONG THE OREGON COAST NORTH OF CAPE  
BLANCO AND INTO THE COQUILLE VALLEY. HOWEVER GRADUAL CLEARING IS  
EXPECTED IN THE MID TO LATE MORNING ON MONDAY. WILL CONTINUE TO  
MONITOR THIS CLOSELY WITH FUTURE MODEL RUNS.  
 
LONG TERM...TUESDAY THROUGH SATURDAY...EXPECT A CHANCE FOR  
THUNDERSTORMS AND SHOWERS TO DEVELOP TUESDAY THROUGH WEDNESDAY AS  
AS SOUTHERLY MOISTURE FEEDS INTO THE AREA FROM AN UPPER LOW OFF  
THE SOUTH-CENTRAL CALIFORNIA COAST. THE BEST CHANCES FOR STORMS  
WILL BE ACROSS NORTHERN CALIFORNIA AND FROM THE CASCADES EASTWARD  
DURING THE AFTERNOON AND EVENING TUESDAY AND WEDENSDAY. THERE IS  
ALSO A SLIGHT CHANCE FOR THUNDERSTORMS AND SHOWERS OVERNIGHT  
TUESDAY NIGHT INTO WEDNESDAY MORNING.  
 
ON THURSDAY, THE RISK FOR THUNDERSTORMS DECREASES AND MODELS SHOW  
AN UPPER TROUGH A WEAK FRONT MOVING INLAND ON THURSDAY. THIS  
FRONT IS EXPECTED TO BRING SOME ISOLATED TO SCATTERED LIGHT  
SHOWERS TO COOS AND DOUGLAS COUNTIES ALONG WITH A MARINE PUSH OF  
LOW CLOUDS. THERE IS A SLIGHT RISK FOR THUNDERSTORMS IN EASTERN  
PORTIONS OF THE AREA AS WELL WITH THIS FRONTAL PASSAGE, MAINLY  
LAKE COUNTY. OTHERWISE, EXPECT COOLER TEMPERATURES TO DEVELOP ON  
THURSDAY OVER THE AREA WITH HIGHS IN THE 80S FOR MOST INLAND  
VALLEYS.  
 
FRIDAY AND SATURDAY, MODELS SHOW GOOD AGREEMENT THAT AN UPPER  
RIDGE WILL REBUILD OVER THE REGION AND A SURFACE THERMAL TROUGH  
WILL DEVELOP ALONG THE COAST. THIS WILL BRING ANOTHER PERIOD OF  
DRY AND HOT WEATHER TO THE AREA WITH PERIODS OF GUSTY TO BREEZY  
NORTHEAST WINDS POSSIBLE IN THE COASTAL MOUNTAINS.  
 

 
   
MFR WATCHES/WARNINGS/ADVISORIES
 
 
OR...RED FLAG WARNING UNTIL NOON PDT SUNDAY FOR ORZ618-619.  
 
CA...NONE.  
 
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 PM PDT SUNDAY  
FOR PZZ350-356-370-376.  
GALE WARNING UNTIL 11 PM PDT SUNDAY FOR PZZ356-376.  
 

 
 
MAS/CC/BTL/FB  
 
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