252
FXUS66 KMFR 282231
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
331 PM PDT MON JUL 28 2025
DISCUSSION
FORECAST CONFIDENCE IS HIGH FOR THE PERIOD FROM THIS
EVENING THROUGH WEDNESDAY NIGHT. THUNDERSTORM ACTIVITY THROUGH THIS
EVENING AND TUESDAY AFTERNOON/EVENING WILL BE ISOLATED TO
SCATTERED, WITH AN AMOUNT OF STORMS IN THE REALM OF WHAT HAS
OCCURRED DURING THE PAST COUPLE OF DAYS. THE MAIN EVENT WILL BE
WEDNESDAY AFTERNOON/EVENING WITH BROADER COVERAGE AND THE
POTENTIAL FOR STRONGER STORMS WITH DOWNPOURS, HAIL, AND GUSTY
WINDS. THROUGHOUT THE PERIOD, THE PROBABILITY WILL BE HIGHEST
FROM THE CASCADES EASTWARD AND ACROSS NORTHERN CALIFORNIA. BUT,
BESIDES THOSE AREAS, A SLIGHT CHANCE EXTENDS INTO SOUTHERN JACKSON
COUNTY TODAY AND TUESDAY, THEN A HIGHER PROBABILITY ACROSS
SOUTHEAST JOSEPHINE, JACKSON, AND EASTERN DOUGLAS COUNTIES LATE IN
THE DAY ON WEDNESDAY. THIS WEATHER IS IN RESPONSE TO A TRAIN OF
TROUGHS MOVING NORTHEAST ACROSS NORTHERN CALIFORNIA.
THERE IS A CHANCE OF THUNDERSTORMS LATER WEDNESDAY NIGHT INTO
THURSDAY MORNING, FOCUSED UPON THE NORTHERN PORTION OF OUR AREA,
INCLUDING STORMS TRACKING ON AN EASTERLY FLOW ACROSS DOUGLAS
COUNTY INTO COOS COUNTY. THIS REGION OF FOCUSED INSTABILITY, IN
THE VICINITY OF THE TROUGH, MAY LINGER OVER THE NORTHERN EDGE OF
OUR AREA ON THURSDAY, BUT IS MORE LIKELY TO SHIFT INTO NORTHERN
OREGON. WEAKER INSTABILITY, IN THE WAKE OF THE TROUGH, COULD
PRODUCE ISOLATED THUNDERSTORMS OVER SOUTH CENTRAL OREGON AND
NORTHERN CALIFORNIA.
MODEL UNCERTAINTY INCREASES ANOTHER NOTCH FOR FRIDAY AND SATURDAY,
BUT CONVECTIVE ACTIVITY LOOKS TO TREND TO LESSER PROBABILITY AND
COVERAGE OF STORMS WITH MORE OF A WESTERLY FLOW ALOFT THAT WOULD
FAVOR A FOCUS ON THE EAST SIDE.
EARLY NEXT WEEK, MODELS ARE TENDING TO COME BACK INTO PHASE WITH
THE BROAD UPPER TROUGH THAT HAS BEEN SITTING OVER THE GULF OF
ALASKA FINALLY PUSHING INTO THE PACIFIC NORTHWEST, WITH BELIEVE IT
OR NOT, A STABLE, SLIGHTLY COOLER PATTERN.
AVIATION...28/18Z TAFS
COASTAL AREAS HAVE REMAINED CLEAR THIS
MORNING, WITH ONLY SCRAPS OF HIGH CLOUDS PASSING OVER THE AREA.
SIMILAR TO SUNDAY MORNING, LIFR LOW CLOUDS AND AREAS OF FOG ARE
EXPECTED FROM BROOKINGS SOUTHWARD AND NORTH BEND NORTHWARD (AS WELL
AS INTO THE COQUILLE VALLEY) BETWEEN AROUND 08Z TO 17Z.
INLAND, VFR LEVELS LOOK TO CONTINUE THROUGH THE TAF PERIOD. HOWEVER,
ISOLATED TO SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON AND
EVENING, MAINLY FROM THE SOUTHERN OREGON CASCADES EASTWARD AND
ACROSS NORTHERN CALIFORNIA. THERE IS ALSO A 10-15% CHANCE FOR
THUNDERSTORMS INTO SOUTHERN JOSEPHINE AND JACKSON COUNTIES. 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.
MARINE...UPDATED 200 PM PDT MONDAY, JULY 28, 2025
SUB-ADVISORY
NORTH WINDS AND LOW SEAS OF 5 FT OR LESS WILL PERSIST THROUGH THIS
EVENING. LATE TONIGHT INTO EARLY TUESDAY MORNING, STRATUS AND FOG
WILL DEVELOP AND LAST AT LEAST INTO MID-MORNING. A RELATIVELY WEAK
THERMAL TROUGH LOOKS TO BRING GUSTY NORTHERLY WINDS AND STEEP SEAS
BETWEEN PORT ORFORD AND PISTOL RIVER TUESDAY MORNING INTO THE
AFTERNOON. THE THERMAL TROUGH WILL STRENGTHEN SLIGHTLY LATE IN THE
DAY ON TUESDAY WITH STEEP SEAS EXPECTED TO EXPAND OVER MUCH OF THE
WATERS SOUTH OF PORT ORFORD THROUGH WEDNESDAY EVENING.
CONDITIONS BRIEFLY IMPROVE WITH LOW PRESSURE IN THE AREA LATER
WEDNESDAY NIGHT INTO THURSDAY. SLIGHT STRENGTHENING OF A THERMAL
TROUGH MAY BRING A RETURN OF STEEP SEAS TO THE SOUTHERN WATERS
THURSDAY AFTERNOON INTO SATURDAY EVENING. -DW
FIRE WEATHER...UPDATED 200 PM PDT MONDAY, JULY 28, 2025
THE
ATTENTION REMAINS ON THUNDERSTORM ACTIVITY EXPECTED THIS WEEK.
TEMPERATURES, HUMIDITIES, AND BREEZY AFTERNOON WINDS WILL ALL REMAIN
NEAR SEASONABLE LEVELS THIS WEEK, SO THE MAIN FIRE WEATHER CONCERN
WILL BE DAILY THUNDERSTORM CHANCES. WE'LL BE IN A RELATIVE LULL IN
TERMS OF THUNDERSTORM COVERAGE TODAY. MAINLY ISOLATED COVERAGE IS
EXPECTED ALONG AND EAST OF THE CASCADES/NORTHERN CALIFORNIA WITH
SOME POCKETS OF SCATTERED ACROSS WESTERN SISKIYOU, NORTHERN KLAMATH
AND EASTERN LAKE COUNTIES.
FROM TUESDAY ONWARD, WE EXPECT A HEIGHTENED LEVEL OF THUNDERSTORM
ACTIVITY THROUGH AT LEAST THURSDAY, WITH THE GREATEST COVERAGE
EXPECTED TO BE WEDNESDAY AND STORMS CONTINUING OVERNIGHT FOR SOME
AREAS INTO THURSDAY MORNING. ANOTHER TROUGH (NEGATIVELY-TILTED)
SWINGS INTO CENTRAL CALIFORNIA, TURNING THE FLOW SOUTHERLY AS IT
TRACKS NORTHWARD THROUGH OREGON. THIS PATTERN WILL MAINTAIN DAILY
THUNDERSTORM CHANCES THROUGH AT LEAST THURSDAY, IF NOT INTO FRIDAY.
CONFIDENCE IS HIGHEST FOR AREAS ALONG AND EAST OF THE CASCADES AND
ACROSS NORTHERN CALIFORNIA TO SEE AT LEAST SCATTERED (IF NOT
WIDESPREAD) COVERAGE DURING THIS PATTERN, BUT THE MORE CHALLENGING
ASPECT IS HOW FAR WEST WILL STORMS MAKE IT, AND WILL THERE BE ANY
OVERNIGHT (NOCTURNAL) THUNDERSTORM POTENTIAL THIS WEEK.
FOR NOW, THE FORECAST SUPPORTS INCREASED THUNDERSTORM ACTIVITY FOR
EAST SIDE/NORCAL BEGINNING ON TUESDAY. WE'VE UPGRADED THE FIRE
WEATHER WATCH FOR TUESDAY TO A WARNING FOR FWZS
285/623(EASTERN)/624/625. FOR FWZ 284, AND OTHER ZONES ACROSS
NORTHERN CALIFORNIA, COVERAGE LOOKS TO BE MOSTLY ISOLATED, THOUGH
ANOTHER POCKET OF SCATTERED IS POSSIBLE ACROSS WESTERN SISKIYOU
(FWZ 280).
AREAL COVERAGE OF STORMS LOOKS GREATEST ON WEDNESDAY WITH THIS DAY
SEEING THE BEST POTENTIAL FOR STORMS WEST OF THE CASCADES. THIS IS
WHEN THE NEGATIVELY TILTED TROUGH NEARS THE FORECAST AREA AND
GUIDANCE SHOWS A SHORTWAVE AT THE BASE OF THIS TROUGH MOVING UP INTO
MODOC COUNTY FROM THE SIERRAS EARLY WEDNESDAY MORNING. THIS WOULD
LIKELY RESULT IN SOME SHOWER ACTIVITY ACROSS THE MODOC, BUT THERE
ISN'T A GOOD SIGNAL FOR LIGHTNING WITH THESE SHOWERS AT THIS TIME.
COULDN'T RULE OUT SOME STRIKES, HOWEVER, WITH ABOUT A 10% CHANCE OF
LIGHTNING. THIS SHORTWAVE STRENGTHENS DURING THE DAY WEDNESDAY WHILE
MOVING NORTHWESTWARD THROUGH THE REGION, RESULTING IN A RATHER
SIGNIFICANT TRIGGER FOR THUNDERSTORM INITIATION. SCATTERED TO
WIDESPREAD THUNDERSTORMS ARE LIKELY ON WEDNESDAY AND WE'VE GONE
AHEAD WITH A FIRE WEATHER WATCH FOR MUCH OF THE AREA (EXCLUDING
615/618/619/282). THE MAJORITY OF ACTIVITY IS EXPECTED DURING THE
AFTERNOON AND EVENING, BUT AS THIS SHORTWAVE SWINGS NORTHWARD IN THE
EVENING AND OVERNIGHT WEDNESDAY, THUNDERSTORM ACTIVITY COULD
CONTINUE ACROSS NORTHERN PORTIONS OF THE FORECAST AREA. WE'VE
STARTED THE WATCH FOR FWZ616 FOR WEDNESDAY EVENING, AND CARRIED IT
THROUGH THURSDAY MORNING. ADDITIONALLY, WE'VE HELD ONTO THE WATCH
FOR 617/623/624/625 THROUGH THURSDAY MORNING AS WELL. AS WE MOVE
INTO THE OVERNIGHT HOURS, THE FOCUS FOR CONCERN SHIFTS TO THE
NORTHERN PORTIONS OF 623/624/625, ROUGHLY NORTH OF A LINE FROM
CRATER LAKE TO SUMMER LAKE. AT THIS TIME, THE NOCTURNAL THREAT LOOKS
LIMITED TO THE NORTHERN AREAS, BUT SUBTLE CHANGES IN THE LOCATION OF
THIS SHORTWAVE COULD CHANGE THAT, SO STAY TUNED FOR UPDATES.
THE CURRENT FORECAST MAINTAINS SIMILAR CONDITIONS ON THURSDAY, BUT
THERE IS SOME UNCERTAINTY ON HOW MUCH THUNDERSTORM COVERAGE WILL
MATERIALIZE DUE TO ANY LINGERING CLOUD COVER FROM OVERNIGHT
ACTIVITY. ADDITIONALLY, WE'LL BE IN A LESS FAVORABLE DYNAMIC REGION
AS THE TROUGH WILL HAVE SHIFTED NORTH OF THE AREA. THE GREATEST
COVERAGE IS MORE LIKELY TO BE WHERE THERE ISN'T CLOUD COVER IN THE
MORNING, WHICH AT THIS TIME LOOKS TO BE EAST OF THE CASCADES AND
ACROSS NORTHERN CALIFORNIA. WE'LL TRY TO HONE IN ON THESE DETAILS
OVER THE COMING SHIFTS.
BY FRIDAY, ACTIVITY SHOULD TREND LESS, HOWEVER, GUIDANCE SHOWS
ADDITIONAL SHORTWAVES MOVING THROUGH IN A WESTERLY FLOW PATTERN.
THIS WOULD RESULT IN DECREASING CHANCES OF STORMS WEST OF THE
CASCADES WHILE MAINTAINING THUNDERSTORM CHANCES EAST OF THE CASCADES
AND ACROSS NORTHERN CALIFORNIA. ON THE OTHER HAND, TEMPERATURES WILL
REMAIN NEAR SEASONAL NORMS, IF NOT A FEW DEGREES BELOW OVER THE
UPCOMING WEEKEND. /BR-Y
MFR WATCHES/WARNINGS/ADVISORIES
OR...FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR ORZ620>622.
RED FLAG WARNING FROM 2 PM TO 11 PM PDT TUESDAY FOR ORZ623>625.
FIRE WEATHER WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
MORNING FOR ORZ616.
FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
MORNING FOR ORZ623>625.
FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
MORNING FOR ORZ617.
CA...FIRE WEATHER WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY
EVENING FOR CAZ280-281-284-285.
RED FLAG WARNING FROM 2 PM TO 11 PM PDT TUESDAY FOR CAZ285.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 3 AM TUESDAY TO 8
PM PDT WEDNESDAY FOR PZZ356-376.
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