786
FXUS66 KMFR 222154
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
254 PM PDT TUE APR 22 2025
DISCUSSION
NORTHWEST FLOW ALOFT CONTINUES TO SUPPORT SEASONABLE
TEMPERATURES AND UNEVENTFUL CONDITIONS ACROSS NORTHERN CALIFORNIA
AND SOUTHERN OREGON THIS AFTERNOON. A WEAK UPPER TROUGH WILL PASS
OVER THE AREA THIS EVENING AND THROUGH THE DAY WEDNESDAY. WINDS MAY
BE A LITTLE BREEZIER THAN NORMAL THIS EVENING, BUT NOTHING REMOTELY
HAZARDOUS IS EXPECTED. THERE WILL BE SOME MODERATE SHOWER CHANCES
(20-40%) ACROSS MODOC, EASTERN SISKIYOU, AND SOUTHERN LAKE COUNTIES
THROUGH THE DAY WEDNESDAY. ANY SHOWERS THAT DO FORM WILL BE ISOLATED
OR SCATTERED. RAINFALL WILL BE MEASURED IN THE HUNDRETHS OF AN INCH,
IF IT EVEN REACHES THE GROUND. INSTABILITY WILL BE WEAK, WITH
PERIODS OF 200-300 J/KG AT MOST ON WEDNESDAY EVENING. LIGHTNING IS
NOT WIDELY EXPECTED, BUT A STRAY STRIKE OR TWO IS NOT IMPOSSIBLE.
CONDITIONS CALM THROUGH THE DAY THURSDAY AS THE PATTERN CHANGES WITH
AN APPROACHING UPPER LEVEL LOW PRESSURE SYSTEM. SOUTHERLY FLOW ALOFT
ALONG THE LEADING EDGE OF THE SYSTEM WILL ALLOW FOR INITIAL SLIGHT
PRECIPITATION CHANCES (15-30%) OVER THE SISKIYOU RANGES AND THE
CASCADES ON THURSDAY AFTERNOON. COOLER DAYTIME TEMPERATURES ARE
FORECAST FOR FRIDAY AND CONTINUE THROUGH THE WEEKEND. WITH THE LOW
EXPECTED TO PASS TO THE SOUTH, GUSTY WINDS ARE NOT A CONCERN THROUGH
THE WEEKEND.
WIDESPREAD PRECIPITATION CHANCES (40-80%) ARE FORECAST FOR FRIDAY AS
THE LOW PASSES TO THE SOUTH. SOUTHERLY FLOW ALOFT ON FRIDAY WILL
BRING MORE SHOWERS TO AREAS WEST OF AND ALONG THE CASCADES AS WELL
AS NORTHERN KLAMATH AND LAKE COUNTIES. HIGHER TERRAIN COULD SEE
BETWEEN 0.5 TO 1.0 INCHES OF RAINFALL, WITH 0.3 INCHES OR LESS OF
RAINFALL FOR LOWER ELEVATION AREAS. SNOW LEVELS OF 5000 FEET WEST OF
THE CASCADES WILL ALLOW FOR 2-4 INCHES OF SNOWFALL OVER SOUTHWESTERN
SISKIYOU COUNTY PEAKS AND RIDGELINES. SNOW LEVELS OF 5500-6500 FEET
ALONG AND EAST OF THE CASCADES WILL KEEP UNREMARKABLE SNOWFALL TO
THE HIGHEST TERRAIN. RAINFALL OVER MODOC AND SOUTHERN LAKE AND
KLAMATH COUNTIES WILL GENERALLY BE 0.1 INCHES OR LESS.
40-80% PRECIPITATION CHANCES CONTINUE ACROSS THE AREA ON SATURDAY,
BUT FLOW ALOFT WILL BE MORE EASTERLY AS THE LOW PASSES OVER
CALIFORNIA. THIS WILL BRING HIGHER PRECIPITATION AMOUNTS TO LAKE AND
MODOC COUNTIES. AMOUNTS ARE STILL UNIMPACTFUL, WITH ONE-FOURTH OF AN
INCH OR LESS OF RAINFALL FORECAST FOR EAST SIDE BASINS. SNOW LEVELS
ALONG AND EAST OF THE CASCADES WILL DROP SLIGHTLY TO 5000-6000 FEET,
ALLOWING FOR 4-8 INCHES OF SNOWFALL OVER WARNER MOUNTAIN PEAKS
THROUGH THE DAY. BLY MOUNTAIN AND THE CASCADES MAY SEE 2-4 INCHES OF
SNOWFALL AT THE HIGHEST ELEVATIONS. THESE AMOUNTS ARE NOT NEAR
PRODUCT THRESHOLDS, BUT EXTRA CAUTION TRAVELING THROUGH THESE AREAS
ON SATURDAY WOULD NOT HURT. RAINFALL OVER WEST SIDE VALLEYS WILL
GENERALLY BE 0.1 INCHES OR LESS.
ACTIVITY STARTS TO DECREASE LATE SATURDAY NIGHT, WITH ANY SUNDAY
SHOWERS LIMITED TO THE CASCADES AND EASTERNMOST LAKE AND MODOC
COUNTIES. HIGH PRESSURE OVER THE PACIFIC OCEAN WILL BRING GENERALLY
DRIER CONDITIONS AND SEASONAL TEMPERATURES THROUGH NEXT WEEK.
METEOGRAM GUIDANCE FOR BOTH THE ECMWF AND GFS SHOW OCCASIONAL WEAK
AND BRIEF PRECIPITATION SIGNALS, AS WELL AS WIDE RANGES IN DAYTIME
HIGHS ACROSS ENSEMBLE MEMBERS. HOW THE HIGH DEVELOPS WILL BE
IMPORTANT FOR RESULTING CONDITIONS NEXT WEEK, BUT IMPACTFUL OR
HAZARDOUS CONDITIONS CURRENTLY LOOK UNLIKELY IN THE LONG-TERM.
-TAD
AVIATION...22/18Z TAFS
STRATUS ASSOCIATED WITH LAST NIGHT'S
MARINE PUSH CONTINUES TO HANG AROUND THE UMPQUA BASIN LATE THIS
MORNING. THIS BROUGHT MVFR CEILINGS TO ROSEBURG FOR A FEW HOURS,
BUT THESE HAVE SINCE SCATTERED OUT AT THE TERMINAL AND EXPECT VFR
TO PREVAIL THROUGH THE REMAINDER OF THE TAF PERIOD (THROUGH 18Z
WEDNESDAY). NORTHERLY WINDS WILL INCREASE AT MOST TERMINALS
THROUGH THIS AFTERNOON, WITH THE STRONGEST WINDS ALONG THE COAST.
WIND GUSTS WILL PEAK AT 30-35KT AT NORTH BEND, WHILE INLAND SITES
WILL GENERALLY SEE WIND GUSTS IN THE 15-25KT RANGE.
AN UPPER LEVEL SHORT WAVE WILL AMPLIFY AS IT MOVES ACROSS THE AREA
TONIGHT. THIS WILL CAUSE CLOUDS TO DEVELOP ACROSS SE SECTIONS
(NE CALIFORNIA INTO SOUTHERN KLAMATH/LAKE COUNTIES). OVERALL,
CONDITIONS LIKELY REMAIN VFR, THOUGH LOCAL MVFR AND TERRAIN
OBSCURATIONS ARE POSSIBLE IN ANY SHOWERS THAT DEVELOP, ESPECIALLY
NEAR THE WARNER MTNS. THESE CLOUDS PERSIST AND SHOWERS REMAIN
POSSIBLE THROUGH WEDNESDAY MORNING. -SPILDE
MARINE...UPDATED 200 PM TUESDAY, APRIL 22ND
MODERATE TO STRONG
WINDS, STRONGEST SOUTH OF GOLD BEACH WILL CONTINUE THROUGH THIS
EVENING. NORTH WINDS WILL GRADUALLY DIMINISH TONIGHT, BUT SEAS WILL
STILL REMAIN ELEVATED ENOUGH FOR SMALL CRAFT CONDITIONS TO CONTINUE
WITH HAZARDOUS SEAS WARNING CONDITIONS SOUTH OF PORT ORFORD INTO
WEDNESDAY EVENING.
CALMER CONDITIONS ARE LIKELY THURSDAY AND FRIDAY. WEAK LOW PRESSURE
WILL MOVE INTO THE WATERS FRIDAY BRINGING SCATTERED SHOWERS. SEAS
ARE EXPECTED TO REMAIN ON THE LOW SIDE WITH NO MARINE HAZARDS ON
FRIDAY. -PETRUCELLI/SPILDE
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 AM PDT
THURSDAY FOR PZZ350-356-370-376.
HAZARDOUS SEAS WARNING UNTIL 11 PM PDT THIS EVENING FOR PZZ350-
356-370-376.
GALE WARNING UNTIL 11 PM PDT THIS EVENING FOR PZZ356-376.
TAD/MAS
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