156
FXUS66 KMFR 121805
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1105 AM PDT TUE MAY 12 2026
UPDATED AVIATION AND MARINE DISCUSSIONS
AVIATION...12/18Z TAFS
VFR PREVAILS ACROSS THE REGION WITH SOME
HIGH CLOUDS STREAMING THROUGH. IFR CONTINUES ALONG THE COAST AND
OVER THE COASTAL WATERS, BUT IS GRADUALLY BREAKING UP FOR THE MORE
INLAND LOCATIONS. SINCE THE FLOW WILL BE MORE ONSHORE TODAY, THERE
COULD BE SOME MORE PERSISTENT CLOUDY AREAS ALONG THE IMMEDIATE
COAST. EXPECT GUSTY SOUTH TO SOUTHWEST BREEZES TODAY, ESPECIALLY IN
NORCAL AND EAST OF THE CASCADES, BUT THERE WILL ALSO BE SOME GUSTY
NORTHWEST BREEZES FOR AREAS WEST OF THE CASCADES TODAY. EXPECT THE
STRONGEST WINDS TO PEAK AROUND 25-30 KT TODAY.
SOUTHERLY FLOW IS IN PLACE OVER THE REGION TODAY AND SOME
INSTABILITY LATE THIS AFTERNOON/EVENING COULD LEAD TO ISO/SCT
SHOWERS (EVEN A THUNDERSTORM?) IN SOME SPOTS FROM WESTERN SISKIYOU
COUNTY UP ACROSS THE SISKIYOUS TO THE CASCADES (THUNDER PROBABILITY
IS ABOUT 10-20% IN THESE AREAS). WITH DECENT MID-LEVEL FLOW ANYTHING
THAT GETS GOING COULD DRIFT OVER THE VALLEYS (MOSTLY JACKSON/EASTERN
DOUGLAS), BUT AS FAR WEST AS ILLINOIS VALLEY, GRANTS PASS AND EVEN
PERHAPS ROSEBURG DURING THE EVENING.
OVERNIGHT, AN UPPER TROUGH WILL MOVE ONSHORE WITH MORE WIDESPREAD
MVFR CLOUDS AND COASTAL SHOWERS SPREADING INLAND BY WEDNESDAY
MORNING. THE SHOWERS COULD REACH NORTHERN KLAMATH AND LAKE COUNTIES
WEDNESDAY MORNING, BUT AREAS SOUTH AND EAST OF THE MOUNTAINS WILL
LARGELY REMAIN DRY WITH VFR. THINGS MOSTLY DRY OUT WITH A MUCH
COOLER AIR MASS WEDNESDAY AFTERNOON. -SPILDE/BR-Y
MARINE...UPDATED 815 AM PDT TUESDAY, MAY 12, 2026
RELATIVELY CALM
CONDITIONS ARE EXPECTED TODAY WITH SUB-ADVISORY SEAS AND WINDS
SHIFTING TO SOUTHWEST BY THIS AFTERNOON. AN INCOMING LOW PRESSURE
SYSTEM WILL BRING SHOWERS LATE TONIGHT INTO WEDNESDAY, ALONG WITH
INCREASING WEST WINDS AND WEST SWELL. DESPITE THIS, BELOW ADVISORY
CONDITIONS ARE EXPECTED TO PERSIST AS SEAS INCREASE SOME, BUT REMAIN
SWELL DOMINATED. GUSTY NORTH WINDS COULD RETURN THURSDAY WITH STEEP
SEAS POSSIBLE BY FRIDAY.
PREV DISCUSSION
/ISSUED 343 AM PDT TUE MAY 12 2026/
DISCUSSION...
A MARINE STRATUS LAYER COVERS SECTIONS OF THE COAST WITH SOME MID
AND HIGH CLOUDS MOVING OVER THE FORECAST AREA THIS MORNING. TODAY
WILL BE AN INTERESTING DAY WITH REGARDS TO SYNOPTIC WEATHER ACROSS
SOUTHERN OREGON AND NORTHERN CALIFORNIA.
A LOW OFF THE OREGON COAST WILL TAKE ON A NEGATIVE TILT LATER
THIS EVENING, PROVIDING SOME EXTRA DYNAMICS FOR CONVECTION AND
STRONG WINDS ACROSS THE FORECAST REGION. IT WILL BE A BREEZY DAY WITH
SUSTAINED WINDS 10 TO 20 MPH WITH GUSTS UP TO 35 MPH EAST OF THE
CASCADES THIS AFTERNOON AND EVENING. IT LOOKS LIKE THE STRONGER
WINDS ALOFT AROUND 9000 FEET SHOW UP LATE IN THE EVENING AND
OVERNIGHT HOURS WHEN WE'RE NOT MIXING, SO WE'LL AVOID THE REALLY
STRONG WINDS.
IN ANY CASE, THERE IS AN ELEVATED FIRE WEATHER RISK EAST OF THE
CASCADES IN LAKE AND MODOC COUNTIES AS WINDS AND HUMIDITIES IN
THE LOWER TEENS COMBINE FOR A FEW HOURS. THE HOT DRY WIND INDEX IS
ABOVE THE 95TH PERCENTILE FOR THIS TIME OF YEAR WITH VALUES
AROUND 200 TO 300, WHICH ISN'T BAD DURING FIRE SEASON, YET
UNUSUALLY HIGH FOR THIS TIME OF YEAR.
THUNDERSTORMS ARE ANOTHER CONCERN, SPECIFICALLY ALONG THE CASCADE
CREST. THE GFS FORECAST SOUNDINGS SHOW UNCAPPED CAPE AROUND 800
J/KG LATER THIS EVENING WITH 0-6KM SHEAR AROUND 50 KNOTS ALONG THE
CASCADE CREST, WHICH IS RATHER HEALTHY. IT LOOKS LIKE THE HIGH
RESOLUTION MODELS ARE MOST AMBITIOUS WITH CONVECTION TO OUR
NORTH, ALTHOUGH WE WOULDN'T BE SURPRISED WITH A FEW THUNDERSTORMS
FIRING NEAR CRATER LAKE THIS AFTERNOON. THE SPC HREF LIGHTNING
PROBABILITY IS AROUND 10% FOR THAT AREA, SO ODDS AREN'T THAT
GOOD.
EVENTUALLY, THIS LOW AND A COLD FRONT WILL PUSH ONSHORE DURING THE
OVERNIGHT HOURS. THE PRECIPITATION MODE ALONG THIS FRONT WILL JUST
BE SHOWERS AND THUNDERSTORMS ARE NOT EXPECTED ALONG THE COAST
OVERNIGHT. MANY WOULD CONSIDER THIS BENEFICIAL RAIN WITH A FEW
TENTHS FALLING ALONG THE COAST WITH A FEW HUNDRETHS FARTHER INLAND
UP TO THE CASCADES.
ONCE THE COLD FRONT MOVES THROUGH, TEMPERATURES WILL TREND NOTABLY
LOWER BY 10 TO 15 DEGREES COMPARED TO TUESDAY. THIS WILL PUSH US
TO MORE NORMAL SPRING WEATHER WITH A BRIEF WARM UP INTO THE 80'S
ON THURSDAY BEFORE WE COOL AGAIN ON FRIDAY. BY SATURDAY, MODELS
ARE BRINGING ANOTHER LOW AND COLD FRONT, ALTHOUGH PRECIPITATION
WILL BE VERY LIGHT OVER OUR AREA. THE BEST CHANCES FOR RAIN WILL
BE TO THE NORTH IN NORTHERN OREGON. THERE IS PRETTY GOOD CONSENSUS
THAT WE DRY OUT AFTER SATURDAY WITH TEMPERATURES WARMING INTO THE
80'S HERE IN MEDFORD NEXT WEEK.
-SMITH
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
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