441
FXUS66 KMFR 290555
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1055 PM PDT SAT JUN 28 2025
..UPDATED THE AVIATION SECTION
AVIATION...29/06Z TAFS
NORTH BEND IS IN THE VICINITY OF A THIN
MARINE LAYER THAT EXTENDS FROM CAPE ARAGO TO CAPE BLANCO. THIS
FEATURE IS EXPECTED TO PERSIST INTO SUNDAY MORNING WITH IFR CEILINGS
LIKELY FOR NORTH BEND IN THE MORNING FROM AROUND 11Z THROUGH 17Z.
VFR IS EXPECTED AT THE COAST SUNDAY, THOUGH WITH STRONGER THAN
TYPICAL LOW LEVEL NORTH WIND GUSTS OF 20 TO 35 KT. A THICKER MARINE
LAYER IS EXPECTED TO BRING IFR TO THE COASTAL AREA FROM CAPE BLANCO
NORTHWARD, INCLUDING THE COQUILLE VALLEY, FROM SUNDAY EVENING INTO
MONDAY MORNING.
ELSEWHERE, SKIES WILL REMAIN VFR THROUGH SUNDAY EVENING WITH TYPICAL
DIURNAL AFTERNOON BREEZES, ON THE LIGHTER SIDE COMPARED TO THE COAST.
PATCHY CUMULUS BUILDUPS ARE EXPECTED SUNDAY AFTERNOON INTO THE
EVENING, OVER THE HIGHER TERRAIN FROM THE CASCADES EASTWARD AND INTO
NORTHERN CALIFORNIA. THIS IS PARTICULARLY SO IN WESTERN SISKIYOU
COUNTY WHERE A FEW ISOLATED THUNDERSTORM WILL BE POSSIBLE.
-DW
MARINE...UPDATED 800 PM PDT SATURDAY, JUNE 28, 2025
A THERMAL
TROUGH ALONG THE SOUTH OREGON COAST HAS RESULTED IN MODERATE TO
OCCASIONALLY STRONG WINDS. THE THERMAL TROUGH WILL ONLY STRENGTHEN
MORE TONIGHT AND PERSIST INTO THE EARLY NEXT WEEK. THE NET RESULT
WILL BE A LONG DURATION OF PERSISTENT MODERATE TO STRONG WINDS, AND
VERY STEEP WIND-DRIVEN SEAS, ESPECIALLY SOUTH OF PORT ORFORD WHERE
GALES ARE LIKELY. MEANWHILE, SMALL CRAFT CONDITIONS WILL EXPAND OVER
THE REST OF THE WATERS. BECAUSE OF THE ABOVE MENTIONED, THE END TIME
FOR THE SMALL CRAFT ADVISORY AND GALE WARNING HAVE BEEN EXTENDED
INTO TUESDAY EVENING. PLEASE SEE MWWMFR FOR MORE DETAILS.
-PETRUCELLI
PREV DISCUSSION
/ISSUED 441 PM PDT SAT JUN 28 2025/
DISCUSSION...TWO MAIN FEATURES REMAIN THE FOCUS OF THE FORECAST
TODAY THROUGH AT LEAST WEDNESDAY: HEAT AND THUNDERSTORMS. THE
UPPER LEVEL PATTERN IS TRANSITIONING TODAY. OVER THE PAST WEEK OR
SO, WE'VE BEEN ON THE SOUTHERN PERIPHERY OF A BROAD WEAK TROUGH
OVER THE PACIFIC NORTHWEST WHICH HAS BROUGHT NEAR NORMAL
TEMPERATURES AND DAILY MARINE PUSHES. THAT CHANGES TODAY AS HIGH
PRESSURE OVER THE DESERT SOUTHWEST EXPANDS NORTHWARD, EXERTING
MORE INFLUENCE IN THE WEATHER OVER SOUTHERN OREGON AND NORTHERN
CALIFORNIA WITH A THERMAL TROUGH AT THE SURFACE. THIS IS BRINGING
CLEAR SKIES ACROSS THE ENTIRE FORECAST AREA, EVEN ALONG THE COAST
AND OVER THE COASTAL WATERS. HIGH TEMPERATURES WILL TREND WARMER
TODAY BY ABOUT 5 TO 10 DEGREES, AND WE'LL SEE ANOTHER ROUND OF
GUSTY AFTERNOON BREEZES TODAY MORE TYPICAL FOR THIS TIME OF YEAR.
THIS INCLUDES ALONG THE COAST WHERE GUSTS UP TO 30 MPH ARE
EXPECTED THIS AFTERNOON, ESPECIALLY NORTH OF CAPE BLANCO.
THE HEAT CRANKS UP ON SUNDAY WITH ANOTHER 5 TO 10 DEGREE WARMING
TREND EXPECTED ACROSS THE REGION FOR SUNDAY AFTERNOON. SUNDAY WILL
BE THE WARMEST DAY OF THIS WARM SPELL FOR AREAS WEST OF THE
CASCADES, THEN MONDAY COULD BE THE WARMEST FOR THE EAST SIDE
(ALTHOUGH CLOUDINESS FROM THUNDERSTORMS AND MONSOONAL MOISTURE
INFLOW COULD LIMIT HIGH TEMPERATURES MONDAY, MORE ON THAT BELOW).
THE WEST SIDE VALLEYS ON SUNDAY WILL SEE HIGHS IN THE UPPER 90S TO
LOW 100S, WHILE THE HIGHS ON MONDAY FOR THE EAST SIDE WILL PEAK OUT
AROUND 90 TO 95. TEMPERATURES WILL THEN COOL SLIGHTLY HEADING
FURTHER INTO NEXT WEEK, BUT WILL REMAIN ABOVE NORMAL. WE DON'T
EXPECT ANY HEAT RELATED HEADLINES WITH THIS EVENT, BUT THERE WILL BE
A MODERATE RISK OF HEAT RELATED ILLNESSES ON SUNDAY AND MONDAY FOR
MUCH OF THE AREA AWAY FROM THE IMMEDIATE COAST. THIS LEVEL OF HEAT
WILL AFFECT MOST PEOPLE SENSITIVE TO THESE TEMPERATURES, BUT
ESPECIALLY FOR THOSE WITHOUT ADEQUATE HYDRATION AND/OR EFFECTIVE
COOLING. TAKE THE PROPER PRECAUTIONS TO PREVENT HEAT ILLNESS, AND IF
SEEKING RELIEF BY SWIMMING IN AREA WATERWAYS, BE ADVISED THAT RIVER
WATER TEMPERATURES ARE STILL COLD, AS THE MORE PERSISTENT SNOWPACK
CONTINUES TO PROVIDE FRESH, COLD, MELTED WATER.
MEANWHILE, WEAK LOW PRESSURE WILL DEVELOP OFF THE COAST OF
CALIFORNIA LATE SATURDAY INTO SUNDAY. THIS LOW PRESSURE WILL LINGER
OFFSHORE THROUGH MONDAY, THEN MEANDER INLAND INTO CENTRAL CALIFORNIA
TUESDAY INTO WEDNESDAY. THIS IS A CLASSIC THUNDERSTORM PATTERN FOR
THE REGION. STARTING SUNDAY, SOUTHERLY FLOW WILL BEGIN TO PUMP MOIST
AND UNSTABLE MONSOONAL MOISTURE INTO THE REGION. THIS COMBINED WITH
WARM SURFACE TEMPERATURES WILL LEAD TO AMPLE INSTABILITY AND WITH
LOBES OF ENERGY ROTATING AROUND THE LOW PRESSURE AS IT MOVES
EASTWARD, WILL ALL COME TOGETHER TO RESULT IN SCATTERED
THUNDERSTORMS ACROSS THE REGION BOTH MONDAY AND TUESDAY. THINGS
COULD GET STARTED AS EARLY AS SUNDAY ACROSS FAR SOUTHERN SISKIYOU
AND MODOC COUNTIES AS MOISTURE FIRST ENTERS THE REGION. AT THE VERY
LEAST, EXPECT PLENTY OF CUMULUS BUILDUPS ALONG THE SISKIYOUS AND
SOUTHWARD. AN ISOLATED SHOWER OR THUNDERSTORM IS NOT OUT OF THE
QUESTION IN THE TYPICAL HOT SPOT NEAR THE TRINITY ALPS, AND THIS HAS
BEEN ADDED TO THE FORECAST. CONFIDENCE IS LOW ON THIS SINCE THE MID-
LEVELS OF THE ATMOSPHERE ARE REALLY JUST BEGINNING TO MOISTEN UP.
THE FORECAST REMAINS CONSISTENT WITH MONDAY AND TUESDAY BEING THE
MOST ACTIVE DAYS, AND WITH MONDAY BEING THE BEST CHANCE FOR STORMS
TO DEVELOP WEST OF THE CASCADES. THESE WILL BE THE DAYS WHERE
MOISTURE AND INSTABILITY WILL BE MOST WIDEPSREAD AND LOBES OF ENERGY
ROTATING FROM SOUTHEAST TO NORTHWEST THROUGH THE FORECAST AREA WILL
PROVIDE SUFFICIENT TRIGGER FOR THUNDERSTORM INITIATION. THERE ARE
SOME INDICATIONS FOR OVERNIGHT CONVECTION AS WELL SUNDAY NIGHT INTO
MONDAY AND AGAIN MONDAY NIGHT INTO TUESDAY. OF THE TWO NIGHTS,
MONDAY NIGHT HAS THE BETTER CHANCE. THERE IS SOME ELEVATED
INSTABILITY PRESENT LATE SUNDAY NIGHT/EARLY MONDAY MORNING, BUT
MOISTURE IS MARGINAL AND THERE ISN'T A CLEAR TRIGGER. IF ENOUGH
INGREDIENTS DID COME TOGETHER, THE BEST CHANCES (10-20)% FOR THIS TO
HAPPEN WOULD BE OVER SISKIYOU COUNTY AND INTO THE KALMIOPSIS
WILDERNESS. CONFIDENCE IN THIS LOW, AS IS TYPICAL WITH OVERNIGHT
CONVECTION AND THE MOST LIKELY SCENARIO HAS CONVECTIVE INITIATION
BEGINNING MONDAY AFTERNOON, ALBEIT MAYBE EARLIER THAN TYPICAL (MAYBE
AROUND 2 PM VS 4 PM). BASED ON PATTERN RECOGNITION, THUNDERSTORMS
ARE POSSIBLE JUST ABOUT ANYWHERE EAST OF THE COASTAL RANGES ON
MONDAY, BUT THE HIGHEST CHANCES FOCUSED ALONG THE KLAMATH, SISKIYOU
AND CASCADE MOUNTAINS AND EAST OF THE CASCADES. STEERING FLOW IS
GENERALLY OUT OF THE SOUTH, BUT THEN VARIES IN DIRECTION AS THE
AFTERNOON PROGRESSES. IT IS ALSO FAIRLY WEAK, SO STORMS ARE LIKELY
TO BE SLOW MOVING. PWATS GET CLOSE TO AN INCH BY THE AFTERNOON
MONDAY, SO THESE STORMS SHOULD BE RAIN PRODUCERS, AND WHEN COMBINED
WITH THE WEAK STEERING FLOW, THERE COULD BE SOME MODERATE TO HEAVY
DOWNPOURS UNDER THE CORE OF THE STORMS.
AS PREVIOUSLY MENTIONED, THERE ARE SOME INDICATIONS THAT CONVECTION
CARRIES INTO THE OVERNIGHT HOURS LATE MONDAY INTO TUESDAY. COVERAGE
OF STORMS WILL DIMINISH LATE MONDAY EVENING, BUT VERY WELL COULD
CONTINUE OVERNIGHT ALONG AND EAST OF THE CASCADES. MOISTURE WILL BE
SUFFICIENT, MODELS INDICATE ELEVATED INSTABILITY, AND WITH THE
REGION UNDER DIFFLUENCE ALOFT, THIS COULD PROVIDE ENOUGH LIFT TO
MAINTAIN SHOWER AND THUNDERSTORM ACTIVITY. AS USUAL, CONFIDENCE IS
LOW IN THIS, ESPECIALLY AT THIS TIME FRAME, BUT WE HAVE ADDED A
SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS TO PORTIONS OF THE CASCADES
FROM CRATER LAKE NORTHWARD AND OVER TO THE WINTER RIDGE/SUMMER LAKE
AREA. THERE IS MUCH MORE CONFIDENCE ON THUNDERSTORMS REFORMING
TUESDAY AFTERNOON, ALTHOUGH WITH THE EASTWARD PROGRESSION OF THE
TROUGH, THE BEST DYNAMICS AND SUPPORT WOULD THEN BE OVER NORTHERN
CALIFORNIA AND ALONG AND EAST OF THE CASCADES. OTHER THAN LOCATION,
STORM BEHAVIOR AND CHARACTER SHOULD BE VERY SIMILAR TO MONDAY. ONE
FLY IN THE OINTMENT TO CONSIDER WILL BE THE AMOUNT OF CLOUD COVER
AROUND ON TUESDAY, ESPECIALLY IF CONVECTION CONTINUES THROUGH THE
PREVIOUS OVERNIGHT HOURS. WITH THIS MUCH MOISTURE ENTERING THE AREA,
AND WITH THE WIDESPREAD CONVECTION EXPECTED MONDAY, THERE MAY BE
EXTENSIVE CLOUD COVER OVER THE AREA TUESDAY LIMITING INCOMING SOLAR
ENERGY, KEEPING TEMPERATURES LOWER, AND LIMITING INSTABILITY. IF
THIS IS THE CASE, THUNDERSTORM COVERAGE WOULD BE SIGNIFICANTLY LESS
THAN WHAT IS CURRENTLY EXPECTED. STAY TUNED AS THIS TIME FRAME
BECOMES RESOLVED BY HIGH-RESOLUTION CONVECTION ALLOWING MODELS
(CAMS) AND WE ARE CLUED IN TO A BETTER PICTURE OF EXPECTATIONS.
AT THIS TIME, WE AREN'T EXPECTING MUCH IN THE WAY OF SEVERE WEATHER
GIVEN THE WEAK WINDS ALOFT, BUT AS ALWAYS WITH THUNDERSTORMS, GUSTY
OUTFLOW WINDS AND DEADLY CLOUD TO GROUND LIGHTNING ARE ALWAYS
ELEMENTS TO BE CONCERNED ABOUT. IF YOU HAVE OUTDOOR PLANS DURING
THIS TIME FRAME, STAY WEATHER AWARE AND HAVE A PLAN FOR SHELTER
SHOULD A THUNDERSTORM DEVELOP NEARBY.
WEDNESDAY THROUGH THE FOURTH OF JULY HOLIDAY WEEKEND...BY WEDNESDAY,
THE UPPER LEVEL LOW RESPONSIBLE FOR ALL THE INSTABILITY SHIFTS FAR
ENOUGH EAST TO LIMIT THUNDERSTORM CHANCES TO FAR EASTERN LAKE AND
MODOC COUNTIES. TEMPERATURES WILL HAVE TRENDED COOLER COMPARED TO
THIS WEEKEND, RETURNING TO NEAR SEASONAL NORMALS. GUIDANCE SHOWS
ANOTHER LOW PRESSURE AFFECTING THE REGION LATE THURSDAY INTO FRIDAY,
BUT COMING THROUGH IN WESTERLY FLOW AND POSITIONED FARTHER NORTH
THAN THE ONE EXPECTED EARLY NEXT WEEK. ONE POSITIVE TO THIS, IS THAT
TEMPERATURES WOULD REMAIN NEAR NORMAL FOR THE FOURTH OF JULY HOLIDAY
AND THUS NO HEAT WAVES FOR THE HOLIDAY. THE FLIP SIDE TO THAT,
HOWEVER, IS THAT THUNDERSTORM CHANCES COULD RETURN TO THE FORECAST
DURING THE HOLIDAY WEEKEND. GIVEN THAT THIS IS A DIFFERENT
PATTERN/TRAJECTORY OF THE LOW PRESSURE, THUNDERSTORM COVERAGE WOULD
LIKELY BE LESS, BUT STAY TUNED AS WE GET PAST THE UPCOMING EVENT AND
DETAILS ON THE NEXT BECOME MORE CLEAR. /BR-Y
FIRE WEATHER...UPDATED 200 PM PDT SATURDAY, JUNE 28, 2025...THE
MAIN CONCERN AHEAD WILL BE ISOLATED TO SCATTERED THUNDERSTORMS FOR
MOST AREAS AWAY FROM THE COAST MONDAY AFTERNOON INTO MONDAY EVENING,
THEN AGAIN TUESDAY AFTERNOON AND EVENING IN NORTHERN CALIFORNIA, AND
CASCADES EAST IN OREGON. CONFIDENCE HAS INCREASE FOR THUNDERSTORMS
TO BE ISOLATED AT FIRST EARLY MONDAY AFTERNOON, WITH STORMS
INCREASING IN NUMBERS AND COVERAGE AS THE AFTERNOON PROGRESSES
MONDAY INTO MONDAY EVENING. STORMS EARLY MONDAY AFTERNOON MAY NOT
PRODUCE MUCH OF ANY PRECIPITATION, THEN THE CHANCE FOR WETTING RAIN
COULD INCREASE MID TO LATE MONDAY AFTERNOON AND EVENING. THE MAIN
REASON FOR THE INCREASE CHANCE IN WETTING RAIN IS STEERING WINDS
WILL BE LIGHT MEANING STORMS WILL BE SLOW MOVERS, THIS PROVIDING THE
BIGGER WINDOW OF OPPORTUNITY FOR STORMS TO PRODUCE LOCALLY MODERATE
TO HEAVY PRECIPITATION. HOWEVER, THAT DOES NOT MEAN THAT ALL STORMS
WILL PRODUCE WETTING RAIN. SOME COULD ALSO PRODUCE LITTLE TO NO
RAIN. KEEP IN MIND, LIGHTNING STRIKES OUTSIDE OF THE PRECIPITATION
CORES ARE POSSIBLE. DUE TO THE PROLONGED PERIOD OF DRY AND WARM TO
HOT WEATHER, LIGHTNING EFFICIENCY WILL BE HIGH TO VERY HIGH FOR FIRE
STARTS. GIVEN THE ABOVE MENTIONED AND INCREASING CONFIDENCE, A FIRE
WEATHER WATCH HAS BEEN ISSUED. PLEASE SEE RFWMFR FOR MORE DETAILS.
WE ALSO HAVE TO BE MINDFUL OF GUSTY AND ERRATIC OUTFLOW WINDS NEAR
AND AWAY FROM THE CORE OF THUNDERSTORMS.
IN THE MEANTIME, DRY WEATHER IS LIKELY THROUGH SUNDAY AFTERNOON,
WITH THE TYPICAL AFTERNOON AND EARLY EVENING BREEZES AND LOW
RELATIVE HUMIDITY. IT WILL BE HOT TODAY WITH AFTERNOON TEMPERATURES
PEAKING OUT SUNDAY WITH NEAR TRIPLE DIGIT VALUES FOR THE INTERIOR
WESTSIDE VALLEYS AND UPPER 80S TO LOW 90S EAST OF THE CASCADES.
SLIGHT COOLING IS EXPECTED WEST OF THE CASCADES, BUT THE EASTSIDE
WILL BE A BIT HOTTER WITH AFTERNOON HIGHS IN THE LOWER 90S. THE
CAVEAT WILL BE THE AMOUNT OF CLOUD COVER MONDAY WHICH IS THERE IS
ENOUGH OF COULD RESULT IN FORECAST HIGHS FOR THE EASTSIDE ENDING UP
LOWER THAN WHATS IN THE FORECAST.
AN UPPER LOW WILL AN UPPER LOW WILL FORM IN CALIFORNIA, AND THIS
WILL BEGIN TO BRING SOME MONSOONAL MOISTURE INTO NORTHERN CALIFORNIA
SUNDAY. BASICALLY SUNDAY IS THE DAY WHERE THE PUMP WILL BE PRIMED
FOR WHAT WE ARE EXPECTING MONDAY AND TUESDAY. THE MOST LIKELY
SCENARIO SUNDAY AFTERNOON WITH THE INCREASE IN MONSOONAL MOISTURE
WILL BE CUMULUS BUILD UPS OVER THE MOUNTAINS AROUND THE TRINITY
HORN, MOUNT SHASTA AND POINTS EAST TO NORTHEAST OF MOUNT SHASTA. THE
WORST CASE WILL BE A FEW ISOLATED STORMS IN THESE AREAS LATE SUNDAY
AFTERNOON INTO SUNDAY EVENING.
TUESDAY, THE THUNDERSTORM THREAT IS EXPECTED TO BE ALONG AND EAST OF
THE CASCADES AND NORTHERN CALIFORNIA. SOME GUIDANCE AND INSTABILITY
PARAMETERS SUGGEST STORMS COULD BE ISOLATED TO SCATTERED TUESDAY
AFTERNOON IN THE SAME FIRE ZONES AS WHAT WERE EXPECTING MONDAY.
THEREFORE IT'S POSSIBLE ANOTHER FIRE WEATHER WATCH COULD BE UP BY
THIS TIME TOMORROW. STAY TUNED.
WEDNESDAY, THE FOCUS FOR STORMS SHOULD BE CONFINED TO PORTIONS OF
LAKE COUNTY AS THE UPPER LOW TO THE SOUTH GETS KICKED EASTWARD AS AN
UPSTREAM UPPER TROUGH MOVES IN FROM THE WEST. EVEN THEN, STORMS ARE
EXPECTED TO BE ISOLATED. -PETRUCELLI
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...FIRE WEATHER WATCH FROM MONDAY AFTERNOON THROUGH MONDAY EVENING
FOR CAZ280-281-284.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 PM PDT TUESDAY
FOR PZZ350-356-370-376.
GALE WARNING UNTIL 11 PM PDT TUESDAY FOR PZZ356-376.
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