478  
FXUS66 KMFR 241034  
AFDMFR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MEDFORD OR  
334 AM PDT SAT JUN 24 2017  
   
DISCUSSION
 
STRONG HIGH PRESSURE AND HOT WEATHER IS THE MAIN  
STORY FOR TODAY. THE UPPER RIDGE IS SHIFTING INLAND OVER THE  
PACIFIC NORTHWEST TODAY WITH THE COASTAL THERMAL TROUGH FOLLOWING.  
THIS TRANSITION BRINGS AN END TO THE OFFSHORE FLOW THAT HAS  
BROUGHT HOT TEMPERATURES AND WINDY WEATHER TO PORTIONS OF THE  
SOUTH COAST OVER THE PAST FEW DAYS, AND WILL INCREASE THE HEAT  
OVER THE INLAND AREAS.  
 
RECORD HIGHS WILL BE TIED OR BROKEN IN MANY INLAND AREAS WITH  
HIGHS RANGING FROM MID 90S TO NEAR 110. AN EXCESSIVE HEAT WARNING  
AND ADVISORY REMAINS IN EFFECT THE HOTTEST LOCATIONS TODAY  
THROUGH SUNDAY AFTERNOON. PLEASE HEED THE SAFETY INFORMATION  
REGARDING HYDRATION, LIMITED OUTDOOR ACTIVITY, CAR SAFETY, AND  
COLD WATER SAFETY.  
 
THE UPPER RIDGE AXIS SHIFTS EASTWARD INTO IDAHO ON SUNDAY WITH A  
ROBUST UPPER LOW APPROACHING THE REGION FROM THE SOUTHWEST. WITH A  
SLIGHTLY COOLER AIRMASS IN PLACE AND INCREASED CLOUDINESS,  
TEMPERATURES WILL COOL OFF SEVERAL DEGREES, BUT IT WILL REMAIN  
HOT.  
 
THUNDERSTORMS ARE POSSIBLE AS THE UPPER LOW USHERS IN MOIST AND  
UNSTABLE SOUTHERLY FLOW SUNDAY AFTERNOON AND EVENING, WITH A  
CONTINUING CHANCE DURING THE OVERNIGHT HOURS. THE CENTER OF THE  
UPPER LOW IS PROGGED TO MOVE ACROSS THE COUNTY WARNING AREA DURING  
THE DAY MONDAY WITH THE MAIN THREAT FOR STORMS OVER THE CASCADES  
AND EAST BUT UNCERTAINTY KEEPS MUCH OF THE WEST SIDE IN SLIGHT TO  
CHANCE PROBABILITIES MAINLY EAST OF A LINE FROM ROSEBURG TO GRANTS  
PASS TO HAPPY CAMP. THE TIMING OF THE LOW MOVING EAST SUGGESTS  
BETTER CONFIDENCE THAT ACTIVITY WILL SHIFT PRIMARILY EAST OF THE  
CASCADES THROUGH MONDAY EVENING.  
 
CONSIDERING A FAIR DEGREE OF INSTABILITY ADVERTISED BOTH DAYS AND  
WELL ABOVE PRECIPITABLE WATER VALUES, SEVERE THUNDERSTORMS COULD  
OCCUR EITHER DAY, HOWEVER MONDAY LOOKS LIKE THE BETTER DAY AS THE  
UPPER JET MOVES IN AHEAD OF THE MAIN SHORTWAVE PROVIDING AMPLE  
WIND SHEAR.  
 
LOW PRESSURE AND COOLER WEATHER PREVAIL OVER THE AREA TUESDAY AND  
WEDNESDAY WITH HIGH PRESSURE REBUILDING LATER IN THE WEEK. STAVISH  
 

 
   
AVIATION...24/00Z TAF CYCLE
 
VFR CONDITIONS WILL CONTINUE AT ALL  
INLAND TERMINALS THROUGH THE TAF PERIOD. A SURGE OF FOG AND LOW  
STRATUS WILL BE WORKING ITS WAY NORTH ALONG THE COASTLINE OVER THE  
NEXT 24 HOURS, AND THERE APPEARS TO BE A GOOD CHANCE FOR MVFR  
VISIBILITY IN LIGHT FOG TO REDEVELOP AT OTH LATE THIS EVENING OR  
OVERNIGHT. KOTH SHOULD CLEAR FOR THE DAY, THEN THE SOUTHERLY  
FOG/STRATUS SURGE IS LIKELY TO MAKE IT TO KOTH BY LATE AFTERNOON.  
-BPN  
 

 
   
MARINE...UPDATED 200 AM SATURDAY, 24 JUNE 2017
 
SOUTH WINDS  
SHOULD REACH CAPE BLANCO BY THIS AFTERNOON, THEN SPREAD NORTH TO  
FLORENCE BY EVENING. UNTIL THEN, RESIDUAL STEEP SEAS WILL  
CONTINUE TO PRODUCE SMALL CRAFT ADVISORY CONDITIONS FOR ALMOST ALL  
AREAS. RELATIVELY CALM CONDITIONS ARE FORECAST FOR EARLY NEXT  
WEEK, THEN THE THERMAL TROUGH IS EXPECTED TO RETURN BY MIDWEEK  
WITH NORTH GALES POSSIBLE AGAIN BY LATE WEEK. MTS/CC  
 

 
   
FIRE WEATHER
 
EXTREMELY HOT, DRY WEATHER CONDITIONS TODAY THROUGH  
THE WEEKEND WILL HELP TO DRY FUELS AND SET THE STAGE FOR POSSIBLE  
FIRE STARTS AS THUNDERSTORMS DEVELOP LATER SUNDAY INTO MONDAY. WHILE  
HEAVIER FUELS ARE STILL WET AND DO NOT NECESSARILY SUPPORT FIRE  
SPREAD OR GROWTH, FINER FUELS ARE APPROACHING SEASONAL DRYNESS  
LEVELS. FURTHERMORE, THERE IS THE POTENTIAL FOR CONSIDERABLE  
LIGHTNING IN THE MOUNTAINS AND NORTHERN EAST SIDE SUNDAY AFTERNOON  
THROUGH MONDAY AFTERNOON AS WELL AS SOME CHANCE FOR NOCTURNAL STORMS  
EVEN OVER THE WEST SIDE SUNDAY NIGHT. IN ADDITION, BREEZY WINDS ARE  
EXPECTED MONDAY AFTERNOON AND TUESDAY. A FIRE WEATHER WATCH  
REMAINS IN EFFECT AND HAS BEEN EXPANDED INTO A FEW AREAS  
INCLUDING SOME OF THE EAST SIDE AND NORTHERN SHASTA VALLEY. CC  
 

 
   
MFR WATCHES/WARNINGS/ADVISORIES
 
 
OR...FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING  
FOR ORZ625.  
HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM PDT SUNDAY FOR  
ORZ023>028.  
EXCESSIVE HEAT WARNING FROM 11 AM THIS MORNING TO 8 PM PDT  
SUNDAY FOR ORZ023>028.  
FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY  
AFTERNOON FOR ORZ621-623.  
FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY  
AFTERNOON FOR ORZ620-622.  
FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY EVENING  
FOR ORZ624.  
 
CA...HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM PDT SUNDAY FOR  
CAZ080-081.  
EXCESSIVE HEAT WARNING FROM 11 AM THIS MORNING TO 8 PM PDT  
SUNDAY FOR CAZ080-081.  
FIRE WEATHER WATCH FROM SUNDAY AFTERNOON THROUGH MONDAY  
AFTERNOON FOR CAZ280.  
FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON  
FOR CAZ281.  
 
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL  
11 AM PDT THIS MORNING FOR PZZ350-356-370-376.  
 

 
 
MTS/MTS/CC  
 
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