066
FXUS66 KMFR 082326
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
426 PM PDT WED APR 8 2026
..NEW AVIATION SECTION
AVIATION (00Z TAFS)
WHILE CONDITIONS ARE EXPECTED TO BE A MOSTLY VFR TAF CYCLE, WE
WILL HAVE THUNDERSTORMS IMPACTING BOTH KMFR AND KLMT WITH THE
OTHER TERMINALS (KOTH/KRBG) LIKELY MISSING OUT ON THUNDERSTORMS
TODAY/TONIGHT. THIS UNSTABLE ATMOSPHERE WILL REMAIN IN PLACE
THROUGH THIS EVENING, BUT STABILITY MAY RETURN AROUND MIDNIGHT
WITH CONDITIONS GENERALLY IMPROVING OVERNIGHT. ANOTHER ROUND OF
THUNDERSTORMS IS ANTICIPATED TOMORROW AFTERNOON AND EVENING WITH
VERY SIMILAR TIMING; HOWEVER, ALL 4 TERMINALS MAY BE IMPACTED BY
THUNDERSTORMS WHICH WILL LIKELY BE REFLECTED IN THE NEXT TAF
CYCLE.
-GUERRERO
PREV DISCUSSION
/ISSUED 259 PM PDT WED APR 8 2026/
DISCUSSION...TEMPERATURES REMAIN JUST ABOVE SEASONAL NORMS THIS
AFTERNOON, WITH CUMULUS STARTING TO DEVELOP OVER ELEVATED TERRAIN
ACROSS NORTHERN CALIFORNIA AND SOUTHERN OREGON. SOUTHERLY FLOW
ALOFT AROUND AN APPROACHING LOW PRESSURE SYSTEM OVER THE PACIFIC IS
PROVIDING BOTH MOISTURE AND INSTABILITY FOR FORECAST THUNDERSTORMS
THIS AFTERNOON AND EVENING. MODEL CAPE VALUES FOR THIS AFTERNOON ARE
IN THE 100-300 J/KG RANGE, WHICH COULD BE ENOUGH TO SUPPORT ISOLATED
TO SCATTERED ACTIVITY. THE HIGHEST CHANCES FOR THUNDERSTORMS TODAY
ARE OVER NORTHERN CALIFORNIA (20-30%), WITH LOWER CHANCES IN
COUNTIES NORTH OF THE CALIFORNIA BORDER (10-20%). PWAT VALUES IN THE
0.5 TO 0.75 INCH RANGE COULD BRING RAIN SHOWERS AS WELL AS LIGHTNING
ACTIVITY. THE HIGHER MODEL CAPE VALUES ARE GENERALLY OVER HIGHER
TERRAIN, WHICH MAY FURTHER LIMIT CHANCES OVER LOWER ELEVATION AREAS.
THUNDERSTORM CHANCES DROP QUICKLY INTO THE EVENING.
ON THURSDAY, SIMILAR DAYTIME HIGHS CONTINUE ACROSS THE AREA. WITH
THE LOW DRAWING CLOSER, CAPE VALUES LOOK TO RISE TO 500-1000 J/KG.
MODEL PWAT VALUES IN THE 0.75-1.0 INCH RANGE ARE PRESENT OVER
WESTERN SISKIYOU AND INTO JOSEPHINE AND DOUGLAS CONTINUES. THIS
COMBINATION OF INSTABILITY AND MOISTURE IS BUILDING 35-40%
THUNDERSTORM CHANCES IN THESE AREAS FOR THURSDAY AFTERNOON.
CONVECTIVE-ALLOWING MODELS (CAMS) SUPPORT ACTIVITY IN THESE AREAS AS
WELL. ANY CHANGE TO HOW MOISTURE OR INSTABILITY DEVELOPS COULD
CHANGE WHERE THUNDERSTORM ACTIVITY IS EXPECTED. CURRENT CHANCES
DECREASE HEADING EASTWARD, WITH 30-35% OVER JACKSON COUNTY AND 15-
30% CHANCES EAST OF THE CASCADES.
LIMITED WIND SHEAR ON BOTH DAYS LOOKS TO LIMIT SEVERE ACTIVITY, BUT
EVEN NON-SEVERE THUNDERSTORMS CAN BRING HAZARDOUS CONDITIONS.
LIGHTNING, ERRATIC GUSTY WINDS, AND LOCALLY HEAVY RAINFALL CAN MAKE
TRAVEL OR OUTSIDE ACTIVITIES DANGEROUS. BE AWARE OF THE CONDITIONS
AROUND IN THE AFTERNOON AND EVENING FOR TODAY AND THURSDAY.
ON FRIDAY, INSTABILITY DECREASES AND THE LOW PRESSURE SYSTEM LOOKS
TO BE CLOSE ENOUGH TO BRING MORE WIDESPREAD SHOWERS. OCCASIONAL
EMBEDDED THUNDERSTORMS OVER WEST SIDE AREAS IS NOT IMPOSSIBLE BUT
NOT WIDELY EXPECTED. ON SATURDAY, A LOW PRESSURE SYSTEM DROPPING
DOWN FROM THE GULF OF ALASKA MEETS THE PACIFIC LOW. THIS WILL BRING
MORE RAINFALL AND COOLER TEMPERATURES. DROPPING SNOW LEVELS
SUPPORT MOUNTAIN SNOWFALL THROUGH SATURDAY AND DECREASING INTO
SUNDAY. WESTERN SISKIYOU AND CASCADES PEAKS AND RIDGES MAY SEE UP
TO A FOOT OF SNOWFALL THROUGH THE WEEKEND WHILE WINTER RIM AND THE
WARNER MOUNTAINS ARE IN THE 5 TO 10 INCH RANGE. EAST SIDE VALLEYS
AND BASINS MAY SEE A FEW TENTH OF AN INCH OF SNOWFALL. GUSTY
WINDS ARE FORECAST EAST OF THE CASCADES ON SATURDAY AFTERNOON, BUT
ARE CURRENTLY SAFELY SHORT OF ADVISORY SPEEDS.
TO BROADLY CONSIDER NEXT WEEK, SCATTERED SHOWERS CONTINUE INTO
MONDAY AS THE UPPER TROUGH AROUND THE LOW EXITS TO THE EAST. A WEAK
RIDGE ON TUESDAY PRECEDES A WEAK MIDWEEK FRONT. MORE WIDESPREAD
ACTIVITY IS POSSIBLE NEXT WEEKEND. -TAD
AVIATION 08/18Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
PERIOD WITH MAINLY MID AND HIGH LEVEL CLOUDS STREAMING THROUGH THE
REGION TODAY. THE MAIN CONCERN THIS AFTERNOON AND EVENING WILL BE
SHOWERS AND THUNDERSTORMS, FOCUSED ALONG THE I-5 CORRIDOR SOUTH OF
THE ROGUE-UMPQUA DIVIDE, ESPECIALLY IN SISKIYOU COUNTY. THIS
INCLUDES MEDFORD, YREKA, AND MT. SHASTA IN THE ROGUE AND SHASTA
VALLEYS.
BOTH MEDFORD AND KLAMATH FALLS TAF SITES HAVE AT LEAST A 30% CHANCE
OF A THUNDERSTORM IMPACTING THE TERMINAL IN THE EARLY EVENING,
AROUND 00Z-04Z. EXPECT GUSTY AND ERRATIC OUTFLOW WINDS IN THE
VICINITY OF ANY THUNDERSTORMS. WHILE CONDITIONS SHOULD REMAIN VFR,
PRECIPITATION COULD TEMPORARILY LOWER CONDITIONS TO MVFR WITH ANY
STRONGER CELLS.
MARINE...UPDATED 1130 AM PDT WEDNESDAY, APRIL 8, 2026...FOR THE
REMAINDER OF THE WEEK, BREEZY NORTH WINDS WILL PERSIST, GENERALLY
REMAINING BELOW ADVISORY CRITERIA. SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE OVER THE WATERS DURING THE AFTERNOONS AND EVENINGS TODAY
THROUGH FRIDAY. THE UPPER LEVEL PATTERN TRANSITIONS OVER THE
WEEKEND, BRINGING LESS THUNDERSTORMS AND MORE WIDESPREAD SHOWER
ACTIVITY INTO EARLY NEXT WEEK. SEAS ARE LIKELY TO REMAIN BELOW
ADVISORY CRITERIA EARLY NEXT WEEK WHILE BREEZY WINDS BECOME WESTERLY
AND SEAS TRANSITION TO NORTHWEST SWELL DOMINATED.
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
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