603
FXUS66 KMFR 271733
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1033 AM PDT SUN JUL 27 2025
DISCUSSION
THE AVIATION AND MARINE SECTIONS OF THE DISCUSSION
HAVE BEEN UPDATED, AND A FORECAST UPDATE HAS BEEN ISSUED WITH SOME
FINE TUNING TO THE PROBABILITY OF THUNDERSTORMS FOR THIS
AFTERNOON/EVENING AND MONDAY AFTERNOON/EVENING. THUNDERSTORM
ACTIVITY TODAY LOOKS TO BE FOCUSED FROM THE SISKIYOU/TRINITY
COUNTY BORDER AREA (SOUTH OF THE SCOTT VALLEY) NORTHEASTWARD
ACROSS CENTRAL AND NORTHEAST SISKIYOU COUNTY INTO SOUTHEAST
KLAMATH AND SOUTHWEST LAKE COUNTIES. BUT, THERE IS A SLIGHT CHANCE
OVER A BROADER PORTION OF THE AREA, GENERALLY SOUHTWARD AND
EASTWARD FROM THE SISKIYOU MOUNTAINS, AND SOUTHERN PORTION OF THE
SOUTHERN OREGON CASCADES. THE OVERALL AREA OF ACTIVITY LOOKS TO BE
SIMILAR ON MONDAY AFTERNOON/EVENING, BUT WITH THE ADDITION OF A
SLIGHT CHANCE FOR JACKSON AND SOUTHEAST JOSEPHINE COUNTIES, AND
THE FOCUS SHIFTED TO THE SCOTT VALLEY INTO THE VICINITY OF YREKA,
AND ALSO NORTHERN KLAMATH COUNTY NEAR CRESCENT.
AVIATION...27/18Z TAFS
ALONG THE COAST, AREAS OF IFR/LIFR
LINGER NEAR BROOKINGS. THESE LOW CLOUDS WILL CLEAR TO VFR THIS
AFTERNOON. LIFR/IFR IS EXPECTED TO RETURN TO THE COAST SOUTH OF GOLD
BEACH AROUND 04Z THIS EVENING, WITH A BROADER AREA OF IFR EXPECTED
ALONG MOST OF THE REMAINDER OF THE COAST AROUND 09Z, INCLUDING NORTH
BEND, AND SPREADING INTO THE COQUILLE AND LOWER UMPQUA VALLEYS. THIS
STRATUS WILL DIMINISH RATHER QUICKLY DURING MONDAY MORNING.
INLAND, OVERALL, SKIES ARE VFR AND WILL REMAIN THAT WAY THROUGH THE
TAF PERIOD. HOWEVER, ISOLATED TO SCATTERED THUNDERSTORMS THIS
AFTERNOON AND EVENING, MAINLY FROM THE SISKIYOU MOUNTAINS AND
CASCADES EASTWARD AND ACROSS NORTHERN CALIFORNIA. THESE COULD
TEMPORARILY LOWER CEILINGS AND/OR VISIBILITY, BUT THE MAIN RISKS
WITH THUNDERSTORMS WILL BE GUSTY OUTFLOW WIND GUSTS, CLOUD TO GROUND
LIGHTNING AND SMALL HAIL. A SIMILAR SCENARIO IS EXPECTED FOR MONDAY
AFTERNOON AND EVENING, WITH THE ADDITION OF A SLIGHT CHANCE OF
THUNDERSTORMS FOR JACKSON AND SOUTHEAST JOSEPHINE COUNTIES.
-DW
MARINE...UPDATED 800 AM PDT SUNDAY, JULY 27, 2025
SUB-ADVISORY
NORTH WINDS AND LOW SEAS OF 5 FT OR LESS, WILL PERSIST INTO TUESDAY
MORNING WITH NIGHTLY STRATUS AND FOG THAT WILL LAST AT LEAST INTO
THE MORNING HOURS EACH DAY. WINDS AND SEAS MAY TREND SLIGHTLY HIGHER
TUESDAY THROUGH THURSDAY, ESPECIALLY SOUTH OF CAPE BLANCO. -DW
PREV DISCUSSION
/ISSUED 414 AM PDT SUN JUL 27 2025/
DISCUSSION...
SATELLITE IS SHOWING PRETTY CLEAR SKIES EXCEPT FOR SOME COASTAL
STRATUS NEAR BROOKINGS AND NORTH OF PORT ORFORD. WE'LL CONTINUE
WITH THE THUNDERSTORM THEME YET AGAIN THIS AFTERNOON AS A DEEP
TROUGH JUST OFF SHORE OVER HELPS DESTABILIZE THE ATMOSPHERE.
THE CLOUD TO GROUND PROBABILITIES ARE LOOKING GOOD WITH THE SPC
HREF SHOWING A WIDE SWATH OF 50 TO 60 PERCENT EAST OF THE CASCADES
AND THE NBM IS A LITTLE MORE CONSERVATIVE AROUND 20 TO 25 PERCENT.
THE ONE THING THAT LOOKS A LITTLE DIFFERENT TODAY IS STORM SHOULD
HAVE A LITTLE MORE MOTION THIS TIME. WINDS BETWEEN THE SURFACE AND
6KM ARE SOUTHERLY ABOUT 20 TO MAYBE 25 KNOTS.
NOT A WHOLE LOT WILL CHANGE BETWEEN SUNDAY AFTERNOON AND MONDAY
AFTERNOON. IT APPEARS THE PROBABILITY OF LIGHTNING DECREASES TO 10
TO 20 PERCENT AND COVERS A GOOD CHUNK OF THE FORECAST AREA. WE
WOULD CHARACTERIZE THE LIGHTNING THREAT AS MORE ISOLATED ON
MONDAY AFTERNOON AND EVENING GIVEN THE CURRENT LIGHTNING
PROBABILITIES. HOWEVER, IT SHOULD BE NOTED THESE STORMS WILL HEDGE
TOWARDS THE DRIER SIDE OF THINGS. THE LEVEL OF FREE
CONVECTION(LFC) PUSHES UP TO ABOUT 10000 FEET EAST OF THE
CASCADES, WHICH IS ON THE HIGHER SIDE. FORECAST SOUNDINGS, SUGGEST
LOW CAPE, BUT STORM MODE SHOULD BE DRIER COMPARED TO YET. GIVEN
THE ISOLATED THREAT, WE MIGHT NOT ISSUE A RED FLAG, ALTHOUGH
IRONICALLY THE IGNITION THREAT AND EFFICIENCY COULD ACTUALLY
INCREASE INTO TUESDAY.
HEADING FURTHER INTO THE WEEK, THE AFOREMENTIONED TROUGH DIGS
INTO THE WEST COAST AND KEEPS THE SHOWER AND THUNDERSTORM GOING
INTO WEDNESDAY. THE FORECAST SOUNDINGS FROM THE GFS SUGGEST MORE
SHOWERS INSTEAD OF THUNDERSTORMS, ALTHOUGH THE NBM PROBABILITIES
HAVE A 20 PERCENT CHANCE OF CLOUD TO GROUND LIGHTNING NEAR ANY
POINT WEDNESDAY AFTERNOON AND EVENING.
WE WERE CONCERNED ABOUT THE THUNDERSTORM THREAT WEDNESDAY NIGHT AS
IT APPEARS THE AXIS OF THE UPPER LEVEL TROUGH DIGS INTO OREGON
WEDNESDAY NIGHT AND THURSDAY. THERE IS STILL A FAIRLY LARGE
SPREAD OF WHERE THESE SHOWERS OR THUNDERSTORMS COULD KICK UP
OVERNIGHT FROM AS FAR NORTH AS WASHINGTON TO AS FAR SOUTH AS OUR
CWA. ENSEMBLE MEMBERS ALSO VARY GREATLY ON WETNESS AT THIS TIME,
SO UNCERTAINTY IS HIGH, ALTHOUGH THE THREAT REMAINS WEDNESDAY
NIGHT. GFS BUFKIT FORECAST SOUNDINGS ALSO BUILD POTENTIAL
INSTABILITY QUICKLY BY THURSDAY MORNING ~10 TO 11AM.
OVERALL, ITS LOOKING LIKE A STORMY WEEK WITH A PERSISTENT THREAT
OF THUNDERSTORMS OVER SOUTHERN OREGON AND NORTHERN CALIFORNIA.
MFR WATCHES/WARNINGS/ADVISORIES
OR...RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS
EVENING FOR ORZ624-625.
CA...RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT THIS
EVENING FOR CAZ280-281-284.
PACIFIC COASTAL WATERS...NONE.
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