827
FXUS66 KMFR 260539
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1039 PM PDT TUE AUG 25 2026
..UPDATED AVIATION DISCUSSION
KEY MESSAGES
* TEMPERATURES CONTINUE TO TREND LOWER THROUGH THE WEEK.
* A DRY COLD FRONT WILL PUSH THROUGH THURSDAY WITH TEMPERATURES
MOVING SLIGHTLY LOWER.
* LOW CHANCE OF RAIN SHOWERS IN MODOC AND LAKE COUNTIES FRIDAY.
DISCUSSION
FAIR WEATHER CUMULUS IS STARTING TO BUILD OVER SOUTH CENTRAL
OREGON WITH PLENTY OF HIGH CLOUDS PASSING THROUGH AS WELL. AN
UPPER LEVEL LOW OFF THE OREGON AND WASHINGTON COASTLINE WILL KEEP
US UNDER A SOUTHERLY TO SOUTHWESTERLY FLOW THIS EVENING INTO
WEDNESDAY MORNING. MAIN WEATHER IMPACT IS SOME COASTAL FOG BASED
OFF THE NBM VISIBILITY AND DEWPOINT DEPRESSION FORECAST.
TEMPERATURES WILL TREND SLIGHTLY COOLER INTO WEDNESDAY AS 500 MB
HEIGHTS LOWER SLIGHTLY. THIS WILL RESULT IN NORMAL HIGH AND LOW
TEMPERATURES FOR LATE AUGUST WITH SOME DEEPER SOUTHERLY TO
SOUTHWESTERLY FLOW.
THE BIGGEST CHANGE WILL BE ON THURSDAY AS THAT UPPER LOW
EVENTUALLY MOVES EASTWARDS AND A DRY COLD FRONT PUSHES TOWARDS THE
COAST. THE LATEST WPC FRONTAL FORECAST HAS A WEAKENING COLD FRONT
AROUND 12Z THURSDAY. LOOKING AT 850MB EQUIVALENT POTENTIAL
TEMPERATURES, IT LOOKS LIKE THE FRONT MIGHT BE MOVING IN A BIT
LATER ON THURSDAY. IN ANY CASE, LOOK FOR AN UPTICK IN WINDS AHEAD
OF THE FRONT WITH SOME SLIGHTLY COOLER AIR MOVING IN THURSDAY
NIGHT FOR LOCATIONS WEST OF THE CASCADES. LOWS WILL FALL INTO THE
MID 50'S FOR LOWS HERE IN MEDFORD, WHICH IS PRETTY TYPICAL FOR
LATE AUGUST.
BY FRIDAY AFTERNOON AND EVENING, WE'LL SEE THE CHANCE OF SHOWERS
INCREASE EAST OF THE CASCADES AROUND MODOC AND SOUTHERN LAKE
COUNTY. THE LATEST RAPID REFRESH ENSEMBLE FORECAST SYSTEM HAS
AROUND 100-300 J/KG OF CONVECTIVE AVAILABLE POTENTIAL ENERGY,
ALTHOUGH NONE OF THE MEMBERS ARE PREDICTING LIGHTNING OVER OUR
AREA. THEREFORE, IT'S LOOKING LIKE PLAIN OLD CONVECTIVE SHOWERS
FOR NOW.
THE ACTIVE WEATHER PATTERN CONTINUES INTO THE WEEKEND AND NEXT
WEEK WITH ANOTHER TROUGH EXPECTED TO PUSH THROUGH THE PACIFIC
NORTHWEST. THE LATEST NBM DOES HAVE A 15-30% CHANCE OF RAIN MAINLY
NORTH OF OUR AREA BEFORE SOME OF THOSE POP VALUES MOVE INTO OUR
AREA TUESDAY. LOOKING AT THE 12Z ECMWF ENSEMBLE, THERE ARE ABOUT
8/50 MEMBERS THAT DO HAVE A COLD FRONT WITH SOME LIGHT RAIN WITHIN
SOUTHERN OREGON. THE REST ARE ESSENTIALLY DRY OR HAVE THE RAIN
MORE FOCUSED TO OUR NORTH NEAR PORTLAND AND SEATTLE. IN ANY CASE,
SOME HOPE FOR RAIN THE EXTENDED FORECAST.
-SMITH
AVIATION (06Z TAFS)
WIDESPREAD MVFR/IFR IN STRATUS ALONG THE COAST AND IN COASTAL
VALLEYS IS EXPECTED TO LOWER TO IFR/LIFR OVERNIGHT. CONDITIONS WILL
GRADUALLY LIFT TO MVFR IN THE LATE MORNING AND EARLY AFTERNOON, WITH
SOME PARTIAL CLEARING ALONG THE COAST POSSIBLE LATE WEDNESDAY
AFTERNOON. WIDESPREAD IFR/MVFR WILL RETURN TO THE COAST WEDNESDAY
EVENING. AREAS OF MVFR CEILINGS MAY SPREAD INTO THE UMPQUA BASIN
EARLY WEDNESDAY MORNING, INCLUDING ROSEBURG, BEFORE CLEARING IN THE
LATE MORNING. ELSEWHERE, FOR INLAND TAF SITES, OTHER THAN HIGH
CLOUDS, WE ARE EXPECTING TYPICAL SUMMER TIME DIURNAL BREEZES WITH
VFR CONDITIONS.
MARINE...UPDATED 130 AM PDT TUESDAY, AUGUST 25, 2026
RELATIVELY
CALM CONDITIONS WITH LIGHT WINDS AND LOW SEAS ARE EXPECTED THROUGH
THE WEEK. SOUTHERLY WINDS WILL PERSIST THROUGH WEDNESDAY, THEN TURN
NORTHERLY ON THURSDAY. NORTH WINDS INCREASE ON FRIDAY SOUTH OF CAPE
BLANCO, BUT WIND DRIVEN SEAS LIKELY HOLD OFF UNTIL THE WEEKEND.
FIRE WEATHER...UPDATED 200 PM PDT TUESDAY, AUGUST 25, 2026
WHILE CONDITIONS WILL APPROACH CRITICAL FIRE WEATHER THRESHOLDS FOR
BOTH WIND AND LOW RH TODAY IN THE SHASTA VALLEY, WE WILL LACK THE
TEMPORAL REQUIREMENT NEEDED WHICH IS 6 HOURS FOR ZONE 281 IN
CALIFORNIA. THAT SAID, WIND SPEEDS WILL BE 20-25 MPH WITH GUSTS
AROUND 30-35 MPH, AND HUMIDITIES WILL BE IN THE LOWER TEENS. THIS
WILL RESULT IN NEAR CRITICAL CONDITIONS THIS AFTERNOON, ESPECIALLY
THROUGH PEAK HEATING WHEN THE STRONGEST WIND SPEEDS AND LOWEST RH
ARE EXPECTED.
FOR TOMORROW AND THURSDAY, WE ARE EXPECTING CRITICAL FIRE WEATHER
CONDITIONS FOR EASTSIDE AREAS AS THE PRESSURE GRADIENT INCREASES
ALONG WITH DRY CONDITIONS. WE HAVE ISSUED A RED FLAG WARNING FOR
TOMORROW AND A FIRE WEATHER WATCH FOR THURSDAY. THIS WILL PRIMARILY
BE FOR SOUTHERN KLAMATH COUNTY, EASTERN/SOUTHERN LAKE COUNTY, AND
NORTH/EASTERN PARTS OF MODOC COUNTY WHERE THE OVERLAP OF STRONG
WINDS AND LOW RH ARE MOST LIKELY. IN OTHER WORDS, THIS IS FOR PARTS
OF FWZS 624 AND 625 IN OREGON AND 285 IN CALIFORNIA. THIS WILL ALSO
BE COMBINED WITH DEEP MIXING THROUGH THE AFTERNOON/EARLY EVENING
HOURS WHICH COULD ALLOW FOR RAPID FIRE GROWTH. HOWEVER, THERE MAY BE
HIGH CLOUDS AROUND EACH DAY WHICH COULD LIMIT MIXING TO SOME DEGREE.
THERE WAS ENOUGH OVERLAP OF VARIABLES TO INCREASE CONFIDENCE FOR THE
THREAT OF CRITICAL FIRE WEATHER CONDITIONS COMING TO FRUITION BOTH
WEDNESDAY AND THURSDAY.
FRIDAY IS SORT OF A TRANSITION DAY AS WE SEE IMPROVING CONDITIONS
BECOMING MORE LIKELY THROUGH THE WEEKEND. HOWEVER, WE MAY STILL SEE
SOME AREAS OF NEAR CRITICAL CONDITIONS FOR SIMILAR AREAS AS
WED/THURS.
MFR WATCHES/WARNINGS/ADVISORIES
OR...RED FLAG WARNING FROM 11 AM TO 8 PM PDT WEDNESDAY FOR ORZ624-
625.
FIRE WEATHER WATCH FROM THURSDAY MORNING THROUGH THURSDAY
EVENING FOR ORZ624-625.
CA...RED FLAG WARNING FROM 11 AM TO 8 PM PDT WEDNESDAY FOR CAZ285.
FIRE WEATHER WATCH FROM THURSDAY MORNING THROUGH THURSDAY
EVENING FOR CAZ285.
PACIFIC COASTAL WATERS...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page