906
FXUS66 KMFR 161740
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1040 AM PDT WED SEP 16 2026
UPDATED AVIATION DISCUSSION
AVIATION...16/18Z TAFS
VFR CONDITIONS PREVAIL FOR MOST AREAS THIS
MORNING, WITH SOME ISOLATED SHOWERS LINGERING EAST OF THE WINTER
RIDGE. MVFR CEILINGS IN THE UMPQUA BASIN WILL GRADUALLY CLEAR TO VFR
BY EARLY AFTERNOON. VFR CONDITIONS WILL PREVAIL THROUGH THE EVENING,
WITH INCREASING CLOUD COVER EXPECTED THIS AFTERNOON FOR INLAND
AREAS. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP
THIS AFTERNOON AND EVENING ACROSS MOST INLAND AREAS, EXCEPT FOR LOW
CHANCES (10%) FOR STORMS IN THE UMPQUA BASIN TO THE NORTH COAST.
STRONG, GUSTY OUTFLOWS ARE POSSIBLE WITH ANY THUNDERSTORMS. LIFR/IFR
RETURNS TO THE COAST LATER TONIGHT. -SPILDE/BR-Y
PREV DISCUSSION
/ISSUED 441 AM PDT WED SEP 16 2026/
KEY MESSAGES...
* BELOW NORMAL TEMPERATURES FOR MOST INLAND AREAS TODAY/THURSDAY
WITH SOME SHOWERS AND THUNDERSTORMS. MAIN RISKS ARE LIGHTNING
AND GUSTY ERRATIC OUTFLOW WINDS WITH THUNDERSTORMS, ESPECIALLY
DURING THE AFTERNOONS/EVENINGS.
* TEMPERATURES REBOUND CLOSER TO NORMAL FRIDAY WITH WARM, DRY
CONDITIONS EXPECTED THIS WEEKEND (ABOVE NORMAL).
* RELATIVELY LOW IMPACT WEATHER CONTINUES EARLY NEXT WEEK WITH
SLIGHT COOLING OVER THE INTERIOR, NIGHTLY MARINE STRATUS
INTRUSIONS NORTH OF CAPE BLANCO, BUT ALSO POSSIBLE WARMING
OFFSHORE WINDS ALONG THE SOUTH COAST.
DISCUSSION...A VIGOROUS SHORT WAVE DIVING SOUTH-SOUTHEASTWARD
INTO OREGON AND NORCAL IS FORMING AN UPPER LEVEL CLOSED LOW
ALMOST DIRECTLY OVERHEAD EARLY THIS MORNING. WHERE FORCING AND
AVAILABLE MOISTURE HAS BEEN GREATEST (JUST TO THE EAST OF THE
LOW'S PIVOT POINT), THIS SYSTEM PRODUCED AN AREA OF SHOWERS AND
THUNDERSTORMS LAST EVENING AND OVERNIGHT, ESPECIALLY FROM NORTH-
CENTRAL SISKIYOU COUNTY UP INTO KLAMATH COUNTY, JUST EAST OF THE
CASCADES AND SOME ARE EVEN BREAKING OUT ACROSS MODOC EARLY THIS
MORNING. RAIN AMOUNTS HAVE BEEN MOSTLY AROUND 0.10 OF AN INCH OR
LESS, BUT A FEW AREAS HAVE SEEN WETTING RAINFALL WITH UP TO 0.47
AT KLAMATH MARSH RAWS. THERE STILL HAVE BEEN A FEW LIGHTNING
FLASHES INTO THE EARLY MORNING HOURS, BUT DO EXPECT THESE TO BE
MOSTLY JUST SHOWERS DURING THE MORNING.
SINCE THE LOW IS CUTTING OFF FROM THE MAIN FLOW ALOFT, IT WILL
JUST HANG OUT IN NW CALIFORNIA TODAY. MODELS CONTINUE TO SHOW
DECENT INSTABILITY (BY OUR AREA'S STANDARDS) WITH MUCAPE OF
200-400 J/KG BENEATH THE COLD CORE ALOFT. AS A RESULT, WE'LL SEE
SHOWERS AND ALSO SOME THUNDERSTORMS REDEVELOP FIRST IN THE NORCAL
MOUNTAINS AND THEN EXTEND INTO SW OREGON. BEST AREA OF INSTABILITY
WILL BE FROM SISKIYOU COUNTY UP ACROSS THE CASCADES THIS
AFTERNOON (COULD ALSO IMPACT KLAMATH BASIN) AND THEN OVER TO THE
WEST SIDE BY THIS EVENING. WITH CYCLONIC FLOW AROUND THE LOW, THIS
WILL RESULT IN STORM MOTIONS FROM SSE TO WNW, BUT PROBABLY NOT
TOO FAST (10-15 KT OR SO), SO THEY SHOULD BE WET WITH PWS
APPROACHING OR EXCEEDING 0.75". MODELS ARE SHOWING SOME DECENT
DCAPE OF AROUND 750-1000 J/KG, ALONG WITH INVERTED-V SOUNDINGS,
INDICATING POTENTIALLY GUSTY OUTFLOW WINDS 40+ MPH IN THE STRONGER
CELLS. IN AREAS THAT DON'T RECEIVE MUCH RAINFALL, THERE IS SOME
CONCERN FOR POTENTIAL FIRE STARTS. THIS SEEMS MOST LIKELY IN
PORTIONS OF NORCAL (ESP SISKIYOU COUNTY) WHERE FUELS ARE DRIER,
AT LEAST COMPARATIVELY SPEAKING TO AREAS FARTHER NORTH, WHERE
RAINFALL WAS GREATER DURING THE FIRST WEEK OF SEPTEMBER. MAIN
HOURS OF CONCERN FOR THUNDERSTORMS IS BETWEEN 2 AND 8 PM, SO THIS
MAY IMPACT OUTDOOR ACTIVITIES PLANNED FOR THIS AFTERNOON/EVENING.
BE SURE TO SEEK SHELTER IF YOU SEE LIGHTNING OR HEAR THUNDER.
BY THIS EVENING, INSTABILITY WILL WANE AND THUNDERSTORMS SHOULD
MOSTLY DIMINISH TO SHOWERS. THE CLOSED LOW WILL MEANDER ACROSS
NORCAL EVENTUALLY SWINGING ACROSS NE CALIFORNIA THURSDAY AND INTO
EASTERN OREGON/NW NEVADA THURSDAY NIGHT. THIS WILL KEEP THE
COOLER THAN NORMAL AIR MASS OVER OUR AREA ALONG WITH ADDITIONAL
SHOWERS AND THUNDERSTORMS. IT STILL APPEARS THE HIGHEST CHANCES
FOR PRECIPITATION WILL BE NEAR AND EAST OF THE CASCADES, BUT WITH
SOME PRECIP POTENTIAL ON THE WEST SIDE AGAIN FROM EASTERN DOUGLAS
COUNTY INTO JACKSON, SOUTHEAST JOSEPHINE AND WESTERN SISKIYOU
COUNTY.
BACK SIDE SHOWERS COULD CONTINUE INTO FRIDAY MORNING OVER THE FAR
EAST SIDE, BUT WE'LL SEE DRIER AIR AND UPPER RIDGING RETURN
ELSEWHERE FRIDAY RESULTING IN TEMPERATURES GETTING BACK CLOSER TO
NORMAL VALUES. AN UPPER RIDGE SHOULD THEN MOVE INTO THE AREA THIS
WEEKEND WITH TEMPERATURES RETURNING TO ABOVE NORMAL. HIGHS IN THE
80S AND LOW 90S WILL BE COMMON FOR WEST SIDE VALLEYS AND IN THE
UPPER 70S TO LOW 80S OVER THE EAST SIDE.
IT LOOKS LIKE A DRY PATTERN WILL CONTINUE INTO EARLY NEXT WEEK
(RAIN CHANCES 10% OR LESS AREA WIDE), BUT WITH ONLY MODERATE
CONFIDENCE IN HOW THAT EVOLVES. MODELS SHOW A CLOSED LOW
MEANDERING OFFSHORE OF THE SF BAY AREA THIS WEEKEND, EVENTUALLY
MOVING ONSHORE NEAR OR JUST SOUTH OF THERE SUNDAY NIGHT INTO
MONDAY (TOO FAR SOUTH FOR MUCH MOISTURE TO GET THIS FAR NORTH)
WITH A TROUGH SWINGING BY TO OUR NORTH EARLY NEXT WEEK. THAT COULD
LEAD TO SOME COOLING OVER THE INTERIOR MONDAY OR TUESDAY. -SPILDE
MARINE...UPDATED 230 AM PDT WEDNESDAY, SEPTEMBER 16, 2026...GUSTY
NORTH WINDS AND STEEP SEAS WILL CONTINUE TODAY AND TONIGHT. STEEP
SEAS COULD LINGER INTO THURSDAY MORNING, THOUGH SHOULD SUBSIDE
INTO FRIDAY. WE EXPECT NORTH WINDS TO INCREASE AGAIN THIS WEEKEND,
WITH STEEP, HAZARDOUS SEAS POSSIBLE AGAIN SATURDAY NIGHT INTO
EARLY NEXT WEEK. -SPILDE
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 5 AM PDT THURSDAY
FOR PZZ350-356-370-376.
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