292
FXUS66 KMFR 311557
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
857 AM PDT THU JUL 31 2025
DISCUSSION
THUNDERSTORMS REMAIN A CONCERN FOR THIS COMING
AFTERNOON AND EVENING, ESPECIALLY IN SISKIYOU, MODOC, KLAMATH, AND
LAKE COUNTIES. LINGERING CLOUD COVER EAST OF THE CASCADES MAY
MITIGATE DAYTIME HEATING SOMEWHAT IF THEY LAST THROUGH THE MORNING
AND INTO THE AFTERNOON. THUNDERSTORM CHANCES HAVE DECREASED WEST
OF THE CASCADES FROM YESTERDAY'S POSSIBILITIES, BUT SOME ISOLATED
ACTIVITY IS POSSIBLE ALTHOUGH UNLIKELY.
PLEASE SEE THE PREVIOUS DISCUSSION FOR MORE DETAILS ON THE SHORT-
AND LONG-TERM FORECAST. -TAD
AVIATION...31/12Z TAFS
IFR CEILINGS AND VISIBILITIES ARE COVERING
MOST OF THE COAST THIS MORNING. WE'RE ANTICIPATING THESE CEILINGS TO
CLEAR OUT LATER IN THE AFTERNOON WITH AMPLE SURFACE HEATING. LOOK
FOR MORE THUNDERSTORMS EAST OF THE CASCADES AND IN NORTHERN
CALIFORNIA THIS AFTERNOON. KLAMATH FALLS WILL HAVE THUNDERSTORMS
IN THE VICINITY OF THE TERMINAL LATER THIS AFTERNOON AND EVENING.
-SMITH
MARINE...UPDATED 800 PM PDT WEDNESDAY, JULY 30, 2025
A THERMAL
TROUGH ALONG THE COAST WILL PERSIST THROUGH FRIDAY EVENING BRINGING
STEEP SEAS AND GUSTY WINDS TO AREAS FROM PORT ORFORD SOUTH. WINDS
AND SEAS WILL PEAK IN THE LATE AFTERNOON AND EVENINGS. WINDS MAY
TREND LIGHTER SATURDAY AND SUNDAY. HOWEVER, CONFIDENCE IS LOW AND
MAY SEE AREAS OF STEEP SEAS AND GUSTY WINDS PERSIST INTO THE WEEKEND
ACROSS THE SOUTHERN WATERS.. THEN, EARLY NEXT WEEK GUSTY WINDS AND
STEEP SEAS ARE LIKELY AGAIN FOR THE WATERS SOUTH OF CAPE BLANCO.
FIRE WEATHER...UPDATED 200 PM PDT WEDNESDAY, JULY 30, 2025
ANOTHER ROUND OF SCATTERED STORMS ARE POSSIBLE THURSDAY, BUT UNLIKE
TODAY, THE FOCUS FOR STORMS WILL BE IN NORTHERN CAL, AND ALONG AND
EAST OF THE CASCADES. 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. ISOLATED STORMS COULD SNEAK THROUGH THE
CRACKS IN PORTIONS OF FIRE ZONES 621 AND 622 LATE THURSDAY AFTERNOON,
AND EARLY THIS EVENING, BUT NOT ENOUGH TO WARRANT A CONCERN. DUE TO
THE EXPECTED SCATTERED STORMS, THE FIRE WEATHER WATCH HAS BEEN
UPGRADED TO A RED FLAG WARNING. PLEASE SEE RFWMFR FOR MORE DETAILS.
FRIDAY, THERE'S GOOD AGREEMENT ANOTHER SHORTWAVE, WITH A SLIGHT
NEGATIVE TILT IS EXPECTED TO MOVE INTO THE AREA DURING THE TIME OF
MAX HEATING AND INSTABILITY. THE COMBINATION OF THE BOTH PLUS A
TRIGGER COULD BE CAUSE FOR CONCERN TO WARRENT ANOTHER FIRE WEATHER
WATCH FOR PORTIONS OF NORTHERN CAL AND EAST OF THE CASCADES FRIDAY
AFTERNOON INTO FRIDAY EVENING. HOWEVER, DUE TO THE TWO HEADLINES
CURRENTLY OUT, AND THAT WERE STILL A FEW DAYS OUT, WE'LL WAIT UNTIL
THE FIRST RED FLAG WARNING TO END, THEN REEVALUATE THE SITUATION
EITHER TONIGHT OR TOMORROW MORNING TO SEE IF ANOTHER HEADLINE IS
NEEDED. STAY TUNED.
FOR THE WEEKEND, SATURDAY PRETTY MUCH LOOKS HO-HUM IN THAT ANY
STORMS SHOULD BE ISOLATED AND CONFINED TO PORTIONS OF FIRE ZONES
280, 281, 624 AND 625 LATE IN THE AFTERNOON AND EARLY EVENING.
SUNDAY, THERE'S GOOD AGREEMENT A STRONGER UPPER TROUGH WILL MOVE
INTO THE AREA SUNDAY AFTERNOON WHICH COULD TRIGGER THUNDERSTORMS
ALONG AND EAST OF THE CASCADES AND NORTHERN CALIFORNIA. ANOTHER
CONCERN FOR SUNDAY COULD ALSO BE MODERATE TO OCCASIONALLY STRONG
WINDS AHEAD OF THE UPPER TROUGH SUNDAY AFTERNOON. -PETRUCELLI
PREV DISCUSSION
/ISSUED 416 AM PDT THU JUL 31 2025/
DISCUSSION...
SHOWERS HAVE MOVED NORTH OUT OF OUR FORECAST AREA AFTER YET
ANOTHER DAY OF THUNDERSTORMS ACROSS THE REGION. LIGHTNING WAS ON
THE HIGHER SIDE TODAY WITH THE NLDN DETECTING ~875 CLOUD TO GROUND
FLASHES WITH THE ENTLN DETECTING AROUND 2900 CLOUD TO GROUND
FLASHES. STORMS WERE WET AT TIMES, PERHAPS THE MAJORITY OF THE
TIME, EVEN WITH CLOUD BASES AROUND 10K FEET AND PWATS AROUND 0.6
INCHES ACCORDING TO GFS FORECAST SOUNDINGS. REGARDLESS, SOME RAWS
SITES REPORTED 0.5 TO 0.75 INCHES OF RAIN EAST OF THE CASCADES
WEDNESDAY EVENING, PERHAPS DUE TO MULTIPLE STORMS MOVING OVER THE
SURFACE STATIONS. IN ANY CASE, THAT WAS A LITTLE MORE RAIN THAN WE
WERE EXPECTING.
FINALLY ONTO THE FORECAST, WE SHOULD SEE MORE LIGHTNING ON
THURSDAY, ALTHOUGH THE ATMOSPHERIC PARAMETERS HINT TO WET STORMS
WITH PWATS INCREASING AND NOT AS LARGE INVERTED VS. THE SPC SREF
PROBABILITY FOR OVER 100 CLOUD TO GROUND FLASHES WITHIN 20KM OF
ANY POINT IS AT 6 PERCENT IN NORTHERN CALIFORNIA WITH THE
PROBABILITIES DROPPING OFF THE FARTHER TO THE NORTH AND EAST.
WE'LL KEEP THE RED FLAG WARNINGS GOING FOR NOW GIVEN THAT THE
LIGHTNING WILL BE CONSIDERED ABUNDANT, ALTHOUGH IT'S HARD TO SEE
NEW FIRES STARTING IN THIS ENVIRONMENT IF THEY HAVEN'T REALLY
PICKED UP RECENTLY.
BY FRIDAY, A SHORTWAVE EMERGES FROM CENTRAL CALIFORNIA AND WE
SHOULD SEE MORE THUNDERSTORMS DEVELOP ACROSS THE AREA DURING
FRIDAY AND SATURDAY. FORECAST SOUNDINGS HINT THAT STORMS COULD
LEAN DRIER FRIDAY AFTERNOON. SOUNDINGS SHOW LARGER INVERTED VS
WITH STORM BASES AROUND 10K FEET. IT'S WORTH NOTING THE
PROBABILITY OF CLOUD TO GROUND LIGHTNING TRENDS LOWER FRIDAY AND
SATURDAY. THAT IS INDEED LOWER COMPARED TO THE 80 TO 90 PERCENT
CHANCES WE'VE SEEN OVER THE PREVIOUS FEW DAYS.
SUNDAY IS PRETTY INTERESTING AS A DEEPER WAVE MOVES INTO THE
OREGON COAST. WE WILL LIKELY SEE THUNDERSTORMS MIXED WITH RAIN
SHOWERS BY THE AFTERNOON HOURS. ONE THING THAT IS A BIG CHANGE
WITH THE SUNDAY EVENT IS THAT STORM MOTION SHOULD BE A LITTLE
FASTER WITH 0-6KM SHEAR AROUND 30-40KTS ON THE GFS. A COLD FRONT,
OR AT LEAST SOME COOLER AIR WILL ACCOMPANY THIS WAVE WITH HIGH
TEMPERATURES TRENDING ABOUT 6 DEGREES COOLER COMPARED TO SATURDAY.
THOSE HIGHS WOULD IN FACT PUSH US BELOW NORMAL FOR THIS TIME OF
YEAR.
FINALLY BY NEXT WEEK WE'RE LOOKING AT SOME DRIER WEATHER AND
FINALLY BREAKING THIS THUNDERSTORM STREAK WE'RE CURRENTLY ON.
TEMPERATURES WILL WARM BACK UP TO SUMMER TIME NORMALS THROUGH THE
REMAINDER OF THE WEEK.
-SMITH
MFR WATCHES/WARNINGS/ADVISORIES
OR...RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 8 PM PDT THIS
EVENING FOR ORZ623>625.
CA...RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 8 PM PDT THIS
EVENING FOR CAZ280-281-284-285.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 PM PDT FRIDAY
FOR PZZ356-376.
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