379
FXUS66 KMFR 301657
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
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
AVIATION...30/12Z TAFS
A MARINE LAYER IS IMPACTING THE COAST
WITH IFR CONDITIONS, AND THIS WILL CONTINUE THROUGH THE MORNING
BEFORE IT CLEARS. GUSTY NORTH WINDS WILL BE PRESENT THIS AFTERNOON
AT THE COAST. INLAND SITES WILL REMAIN IN VFR THROUGH MOST OF THIS
CYCLE.
THUNDERSTORMS WILL BEGIN TO IMPACT THE AREA LATE MONDAY AFTERNOON.
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 AFTERNOON THROUGH EARLY EVENING. STORMS WILL BE
MOST NUMEROUS BETWEEN 22Z AND 03Z, FROM SISKIYOU COUNTY INTO
JACKSON, KLAMATH, AND NORTHERN LAKE COUNTIES. THIS INCLUDES THE
CASCADE CREST, YREKA, ASHLAND, AND KLAMATH FALLS.
-GUERRERO/HERMANSEN
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.
MAS/MAS/MAS
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