064
FXUS66 KMFR 311005
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
305 AM PDT MON AUG 31 2026
KEY MESSAGES
* RAIN IS LIKELY WEDNESDAY AFTERNOON INTO THURSDAY WEST OF THE
CASCADES WITH LIGHTER RAIN EAST OF THE CASCADES.
* ROCKSLIDES ALONG HIGHWAYS 38,42 AND 138 ARE POSSIBLE WITH THIS
FIRST RAIN OF THE SEASON. LESS LIKELY IN OTHER AREAS.
* 15 TO 20 DEGREES COOLER THAN NORMAL WEDNESDAY INTO THURSDAY.
DISCUSSION
NOT MUCH GOING THIS MORNING AS SOME COASTAL STRATUS CREEPS UP THE
COAST. TEMPERATURES WILL TREND WARMER THIS AFTERNOON INTO THE
LOWER 90'S FOR HIGHS HERE IN MEDFORD. ONE COULD ANALYZE A WEAK
THERMAL TROUGH OVER OUR AREA THIS MORNING AND AFTERNOON WITH
INVERTED 850 MB HEIGHTS AND SOME LIGHT EASTERLY FLOW ALOFT. IN ANY
CASE, THIS BRIEF PERIOD OF WARMER TEMPERATURES AND DRY CONDITIONS
WILL COME TO AN END IN THE NEXT FEW DAYS.
AN UPPER LEVEL WAVE AND EMBEDDED SHORT WAVE WILL PUSH INTO
NORTHERN CALIFORNIA AND SOUTHERN OREGON SOMETIME AROUND TUESDAY
AFTERNOON. THE LATEST FORECAST HAS THE PROBABILITY OF
PRECIPITATION INCREASING INTO TUESDAY AFTERNOON. THE PRECIP LOOKS
SPOTTY, SO IT WILL BE MORE MISS THAN HIT. THE NBM THUNDERSTORM
PROBABILITY IS ABOUT 10%, SO A FEW RUMBLES OF THUNDER ARE NOT OUT
OF THE QUESTION.
A DEEPER WAVE WILL EVENTUALLY MOVE INTO THE PACIFIC NORTHWEST WITH
WHAT APPEARS TO BE WARM FRONT MOVING INTO THE COAST AROUND 18Z.
THIS SHOULD LEAD TO A MORE WIDESPREAD LIGHTER RAIN ALONG THE
BOUNDARY AS IT MOVES EASTWARD. A COLD FRONT SHOULD QUICKLY FOLLOW
THE WARM FRONT AROUND 0Z WITH OR PERHAPS IT WILL COME IN AS AN
OCCLUDED FRONT. IN ANY CASE, THERE SHOULD BE STRONG SYNOPTIC LIFT
AND PLENTY OF PRECIP ALONG THESE BOUNDARIES BY WEDNESDAY EVENING.
THE LATEST FORECAST HAS AN INCH OF RAIN ALONG THE COAST FROM 12Z
WEDNESDAY TO 12Z THURSDAY WITH NOTABLY LESS PRECIPITATION FARTHER
EAST. SOME AREAS WEST OF THE CASCADES COULD SEE UP TO 0.5 INCHES
WHILE LOCATIONS AROUND LAKE, KLAMATH AND MODOC COUNTIES WILL SEE
SIGNIFICANTLY LESS. IN FACT, ALTURAS IS EXPECTED TO STAY DRY INTO
THURSDAY MORNING.
THERE COULD BE IMPACTS FROM THIS FIRST RAIN OF THE SEASON WITH ROCK
SLIDES/LANDSLIDES ALONG THE USUAL SPOTS AROUND HIGHWAYS 42, 38
AND 138. THE EAST EVANS CREEK AND FIELDER MOUNTAIN BURNSCARS COULD
BE AN ISSUE AS WELL. SOME OF THIS IS DEPENDENT ON THE SEVERITY OF
THE BURN AREAS, ALTHOUGH THE FIRST LIGHT RAIN WILL TEST THESE
BURNSCARS FOR SMALLER DEBRIS FLOWS.
LASTLY, THE FIRST RAIN OF THE SEASON AFTER LONGER PERIODS OF DRY
WEATHER CAN CREATE SLICK ROADWAYS FROM THE OIL BUILDUP THROUGH THE
SUMMER MONTHS. THE THREAT OF ACCIDENTS CAN INCREASE AFTER THESE
LONG DRY STRETCHES, SO ONE SHOULD USE EXTRA CAUTION DRIVING
WEDNESDAY AFTERNOON AND EVENING AS A LIGHTER RAIN COULD PUSH THE
OIL TO THE SURFACE WITHOUT RUNNING OFF THE ROAD.
EVENTUALLY, THIS UPPER LEVEL WAVE WILL MOVE EASTWARDS THURSDAY
AND FRIDAY. IT LOOKS LIKE ANOTHER COLD FRONT COULD BRING A QUICK
SHOT OF RAIN TO OUR FORECAST AREA WITH A FOCUS ON NORTHERN
CALIFORNIA ON THURSDAY EVENING. ALTHOUGH ENSEMBLES ARE DIVIDED ON
THE AMOUNT OF RAIN, ALMOST ALL GUIDANCE BRINGS THIS LOW OVERHEAD
WITH SCATTERED SHOWERS INTO FRIDAY.
EVEN THOUGH THIS RAIN WILL BE UNCOMMON FOR EARLY SEPTEMBER, WE'RE
NOT EXPECTING ANY RAINFALL RECORDS RIGHT NOW, OR THE PROBABILITY FOR
BREAKING A PRECIPITATION RECORD IS PRETTY LOW. HOWEVER, WE COULD
SET A RECORD MINIMUM/LOW TEMPERATURE IN THE SUMMER, WHICH SEEMS
LIKE A RARITY THESE DAYS. KLAMATH FALLS IS FORECAST TO HIT 32
DEGREES ON THURSDAY NIGHT AND THE OLD RECORD IS 32 SET IN 1912.
THIS SEEMS UNLIKELY WITH A LOT OF CLOUD COVER AROUND AND THE
UPPER LOW OVERHEAD. THE NBM/WPC FORECAST IS PROBABLY BIAS
CORRECTING LOWER DUE TO ALL THE CLEAR SKIES WE'VE HAD OVER THE
PREVIOUS WEEKS. THE GFS MOS GUIDANCE HAS A LOW OF 40, WHICH SEEMS
MORE REASONABLE. IN ANY CASE, THIS WILL HAVE TO BE WATCHED.
HEADING INTO THE WEEKEND, IT LOOKS LIKE THE FORECAST DRIES OUT
EVEN THOUGH THE UPPER LEVEL LOW REMAINS OVERHEAD. TEMPERATURES
WILL REMAIN COOLER THAN NORMAL WITH HIGHS IN THE UPPER 70'S WITH
PLENTY OF CUMULUS CLOUD COVER EXPECTED THROUGH THE DAY. WPC/NBM
DOES HAVE SOME POPS ALONG HIGHER TERRAIN, SO A STRAY SHOWER CAN'T
BE RULED OUT. THERE ARE A FEW(3-5) VERY WET ENSEMBLE MEMBERS
SUNDAY WITH MANY STAYING DRY, SO QUITE A QPF SPREAD AROUND DAY
6-7.
-SMITH
AVIATION...31/06Z TAFS
VFR LEVELS UNDER CLEAR SKIES PERSIST
ACROSS NORTHERN CALIFORNIA AND SOUTHERN OREGON. MVFR/IFR CEILINGS
ARE POSSIBLE ALONG THE COAST LATE TONIGHT INTO EARLY MONDAY MORNING,
BUT A SLIGHT EASTERLY COMPONENT TO WINDS MAY LIMIT CEILING
DEVELOPMENT. EITHER WAY, CLOUDS WILL INCREASE ALONG THE COAST
THROUGH THE AFTERNOON AND EVENING AS THE LEADING EDGE OF AN UPCOMING
SYSTEM APPROACHES THE AREA AND WINDS BECOME ONSHORE. MVFR/IFR
CEILINGS WILL PREVAIL ALONG THE COAST AND OTHER AREAS ALONG AND WEST
OF THE COASTAL MOUNTAINS, WITH POTENTIALLY SOME DRIZZLE, BY MONDAY
EVENING. ELSEWHERE, VFR WILL CONTINUE THROUGH THE NEXT 24 HOURS,
WITH SOME MID LEVEL CLOUDINESS EXPECTED TO DEVELOP WEST OF THE
CASCADES BY EVENING.
MARINE...UPDATED 230 AM PDT MONDAY, AUGUST 31, 2026
CONDITIONS HAZARDOUS TO SMALLER CRAFTS WILL EASE THIS MORNING WITH
WEAKENING WINDS ACROSS ALL OF THE WATERS. SEAS WILL FALL TO 4 TO
5 FEET WITH A NORTHWEST SWELL AROUND 3 TO 4 FEET AT 10 SECONDS.
THE BIG CHANGE WILL COME ON WEDNESDAY MORNING AS A WARM FRONT
FIRST PUSHES THROUGH THE WATERS AND KICKS UP SOME STRONGER
SOUTHERLY WINDS. CONDITIONS WILL BE HAZARDOUS TO SMALLER CRAFTS
DURING THIS TIME. EVENTUALLY, A COLD FRONT WILL MOVE THROUGH THE
WATERS CLOSER TO WEDNESDAY EVENING. THIS COLD FRONT WILL LIKELY
PRODUCE GALE FORCE WIND GUSTS AROUND 45 KNOTS. THEREFORE, WE HAVE
ISSUED A GALE WATCH BETWEEN TUESDAY NIGHT INTO WEDNESDAY
AFTERNOON.
-SMITH
FIRE WEATHER...UPDATED 200 PM PDT SUNDAY, AUGUST 30, 2026
A BRIEF, BUT STRONG WARMING AND DRYING TREND WILL CONTINUE ON
MONDAY. WINDS WILL INCREASE MONDAY AFTERNOON AS A TROUGH APPROACHES
FROM THE WEST. WIND AND HUMIDITY CONDITIONS WILL REACH CRITICAL
LEVELS IN THE SCOTT AND SHASTA VALLEYS AND EAST OF THE CASCADES DUE
TO GUSTY SOUTH TO SOUTHWEST WINDS AND DRY HUMIDITIES. A RED FLAG
WARNING IS IN EFFECT FOR PORTION OF FWZ 280 (SCOTT VALLEY) AND FWZS
281, 284, 285, AND 624.
ON TUESDAY, GUSTY WINDS WILL AGAIN REACH CRITICAL LEVELS IN THAT
AREA. BUT, HUMIDITIES WILL BE SLIGHTLY ABOVE THRESHOLDS AS
TEMPERATURES TREND COOLER. THERE WILL ALSO BE CHANCES FOR LIGHT
SHOWERS AND A 5%-15% PROBABILITY OF LATE OF DAY THUNDERSTORMS,
ESPECIALLY NEAR THE SCOTT VALLEY IN WEST-CENTRAL SISKIYOU COUNTY,
AND IN FAR NORTHERN KLAMATH COUNTY.
A TROUGH DOMINATED PATTERN WILL FOLLOW FOR THE REMAINDER OF THE WEEK
WITH A STRONG COOLING TREND AND INCREASING CHANCES FOR RAIN. GUSTY
WINDS, AND A WETTING RAIN ARE LIKELY FROM THE COAST TO THE CASCADES,
AND IN NORTHERN KLAMATH COUNTY. THIS WILL BE FOLLOWED BY SHOWER
CHANCES FRIDAY INTO SUNDAY WHILE SLIGHTLY WARMER TEMPERATURES REMAIN
BELOW NORMAL. THE OUTLOOK FOR DAY 8-10, EARLY NEXT WEEK, IS FOR
WARMING AND DRYING.
MFR WATCHES/WARNINGS/ADVISORIES
OR...RED FLAG WARNING FROM NOON TODAY TO 8 PM PDT THIS EVENING FOR
ORZ624.
CA...RED FLAG WARNING FROM NOON TODAY TO 8 PM PDT THIS EVENING FOR
CAZ280-281-284-285.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 5 AM PDT EARLY
THIS MORNING FOR PZZ350-356-370-376.
GALE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY AFTERNOON
FOR PZZ350-356-370-376.
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