239
FXUS66 KMFR 301759
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1059 AM PDT MON JUN 30 2025
UPDATED AVIATION DISCUSSION
AVIATION...30/18Z TAFS
THE MARINE LAYER CONTINUES TO BRING
LIFR/IFR CONDITIONS TO THE COAST NORTH OF CAPE BLANCO AND OVER MUCH
OF THE COASTAL WATERS. CONDITIONS AT COASTAL SITES, INCLUDING NORTH
BEND, ARE EXPECTED TO IMPROVE TO VFR THIS AFTERNOON AS THE MARINE
LAYER PEELS BACK TO THE IMMEDIATE COAST.
FOR INLAND LOCATIONS, VFR CONDITIONS ARE EXPECTED THROUGH THE TAF
PERIOD. HOWEVER, SCATTERED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON
FIRST ACROSS NORTHERN CALIFORNIA AROUND 21Z, THEN SPREAD
NORTHWESTWARD TO IMPACT INTO PORTIONS OF KLAMATH/JACKSON/JOSEPHINE
COUNTIES AROUND 00Z-03Z. STRONG GUSTY ERRATIC OUTFLOWS UP TO 30-40
KTS ARE POSSIBLE WITH THESE STORMS ALONG WITH HAIL. ROSEBURG WILL
LIKELY BE TOO FAR NORTH TO SEE ANY ACTIVITY, BUT BOTH KMFR AND KLMT
WILL HAVE DECENT CHANCES (40-50%) AT BEING IMPACTED BY THUNDERSTORMS
LATE THIS AFTERNOON THROUGH EARLY EVENING.
CURRENT GUIDANCE FIZZLES OUT THUNDERSTORM ACTIVITY AFTER 03Z, BUT
ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE OVERNIGHT INTO
TUESDAY MORNING. MEANWHILE, EXPECT THE RETURN OF MARINE STRATUS TO
SIMILAR AREAS AGAIN TONIGHT, RESULTING IN IFR/LIFR CONDITIONS.
/BR-Y
PREV DISCUSSION
/ISSUED 957 AM PDT MON JUN 30 2025/
DISCUSSION...SATELLITE IMAGERY IS SHOWING CLEAR SKIES THIS
MORNING ACROSS INTERIOR SW OREGON AND NORTHERN CALIFORNIA, BUT
MARINE STRATUS SHROUDS COASTAL DOUGLAS, COOS AND SOUTHERN CURRY
COUNTIES. OFFSHORE FLOW IS BRINGING CLEAR SKIES FROM PORT ORFORD
TO AROUND GOLD BEACH.
SURFACE HEATING WILL SEND TEMPERATURES WELL INTO THE 90S TO NEAR
100 DEGREES AGAIN THIS AFTERNOON IN MANY INLAND LOCATIONS, SO BE
SURE TO STAY HYDRATED IF OUTSIDE FOR EXTENDED DURATION.
THE MAIN WEATHER FEATURE ASIDE FROM THE HEAT WILL BE THE
POTENTIAL FOR THUNDERSTORMS THIS AFTERNOON/EVENING. LOW PRESSURE
IF OFF THE CALIFORNIA COAST AND WE CAN ALREADY SEE MID-LEVEL
MOISTURE ADVANCING TO THE NORTHWEST AROUND IT. WE ARE PLANNING TO
DO AN 18Z SOUNDING IN SUPPORT OF THE MARGINAL RISK FOR SEVERE
THUNDERSTORMS THAT WE ARE CURRENTLY UNDER FROM SPC. MODELS ARE
SHOWING SOME HEALTHY INSTABILITY AND VERY STEEP LAPSE RATES
DEVELOPING AS A VORT LOBE SWINGS NORTHWESTWARD THIS AFTERNOON
COINCIDING WITH PEAK HEATING. CURRENT CAM GUIDANCE IS SHOWING
THUNDERSTORMS BEGINNING IN NORCAL IN THE 2-4 PM TIME FRAME WITH
MOVEMENT OFF TO THE NORTHWEST. WESTERN MODOC AND SISKIYOU COUNTIES
WILL SEE ACTION FIRST, THEN THE STORMS SHOULD SPREAD INTO
SOUTHERN OREGON THIS EVENING (4-6 PM), EVENTUALLY DISSIPATING AS
SHOWERS OVERNIGHT WITH THE LOSS OF INSTABILITY. WITH THE STRONG
SURFACE HEATING, SOUNDINGS ARE SHOWING A DRY SUB CLOUD LAYER AND
ROBUST DCAPE (1000-1500 J/KG), SO THESE STORMS WILL HAVE THE
ABILITY TO PRODUCE SOME STRONG GUSTY OUTFLOWS OF 40-60 MPH. IN
ADDITION TO THE WIND GUSTS, STORMS CAN PRODUCE HAIL AND NUMEROUS
CLOUD TO GROUND LIGHTNING FLASHES. IT SHOULD BE NOTED THAT DESPITE
THE DRIER SURFACE LAYER TO START, PWATS INCREASE TO 0.75-1.00, SO
STORMS THAT HAVE SOME DRY LIGHTNING INITIALLY WILL BECOME WETTER
AS TIME GOES ON AND COULD PRODUCE HEAVY DOWNPOURS. THE MAIN
QUESTION ALWAYS SEEMS TO BE HOW MUCH ACTIVITY WILL BE ABLE TO COME
OFF THE TERRAIN (CASCADES/SISKIYOUS) AND INTO THE VALLEYS. THERE
ARE COMPETING FORCES AT WORK HERE, STEERING FLOW IS ON THE WEAK
SIDE AND THE INSTABILITY DROPS OFF TO THE NW, WHERE THERE'S ALSO
LOTS OF CONVECTION INHIBITION (CIN). THINK THESE STORMS PEAK IN
INTENSITY IN THE 3-7 PM RANGE, THEN WILL TEND TO FIZZLE AS THE SUN
SETS. IT APPEARS THAT THE ROSEBURG AREA WILL BE ON THE NW FRINGES
OF T-STORM CHANCES (LOW PROBABILITY AROUND 15%). HIGHEST
PROBABILITIES WILL BE IN NORCAL (60-70%) AND AROUND 40% CHANCE
HERE IN MEDFORD. KEEP AN EYE TO SKY THIS AFTERNOON AND EVENING AND
IF YOU SEE LIGHTNING OR HEAR THUNDER, SEEK SHELTER. ACTIVITY
OVERNIGHT IS POSSIBLE, BUT THINK MOSTLY SHOWERS AS OPPOSED TO
THUNDERSTORMS. CAN THERE BE A THUNDERSTORM, YES, BUT JUST NOT AS
WIDESPREAD AS THE STORMS THIS AFTERNOON/EVENING.
WITH THE LOW MOVING CLOSED TO THE CALIFORNIA COAST ON TUESDAY,
WE'LL LIKELY HAVE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WITH
JUST A SLIGHT EDGE EASTWARD IN THE GREATEST ACTIVITY. THIS MEANS
GENERALLY FROM THE CASCADES/SISKIYOUS SOUTH AND EAST, BUT THERE
STILL COULD BE ISOLATED ACTIVITY WEST OF THE CASCADES, INCLUDING
HERE IN MEDFORD. THE LIGHTNING RISK SHIFTS FURTHER EASTWARD ON
WEDNESDAY WITH JUST SLIGHT CHANCES REMAINING OVER SE PORTIONS OF
THE CWA (MOSTLY S AND E OF KLAMATH FALLS). -SPILDE
MARINE...A THERMAL TROUGH WILL MAINTAIN MODERATE TO STRONG NORTH
WINDS AND STEEP TO VERY STEEP WIND-DRIVEN SEAS THROUGH AT LEAST
TUESDAY EVENING. THE STRONGEST WINDS AND STEEPEST SEAS WILL BE
SOUTH OF PORT ORFORD. CONDITIONS COULD START TO IMPROVE AS EARLY
AS WEDNESDAY BUT MORE LIKELY BY THURSDAY.
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 8 PM PDT THIS
EVENING FOR CAZ280-281-284.
FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
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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