592
FXUS66 KMFR 162153
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
253 PM PDT FRI MAY 16 2025
DISCUSSION
CLOUD COVER IS REBUILDING THIS AFTERNOON AHEAD OF
AN APPROACHING UPPER TROUGH. THE FIRST IMPACTS FROM THIS
APPROACHING SYSTEM WILL BE THUNDERSTORM CHANCES DEVELOPING EAST OF
THE CASCADES LATE TONIGHT INTO EARLY SATURDAY MORNING. THE BEST
CHANCES (10-15%) WILL BE ACROSS MODOC AND SOUTHERN LAKE COUNTIES,
WITH LESSER CHANCES (5-10%) COVERING EASTERN KLAMATH AND NORTHERN
LAKE COUNTIES. ANY THUNDERSTORMS THAT DEVELOP ARE LIKELY TO BE
ISOLATED AND REMAIN BELOW SEVERE THRESHOLDS. THUNDERSTORM CHANCES
INCREASE TO 15-20% ACROSS LAKE AND MODOC COUNTIES ON SATURDAY
AFTERNOON BEFORE DECREASING THROUGH SATURDAY EVENING AND NIGHT.
OTHER AREAS ARE EXPECTED TO SEE AT LEAST LIGHT SHOWERS AT SOME
POINT BETWEEN SATURDAY MORNING AND SUNDAY AFTERNOON. OVERALL
AMOUNTS WILL BE UNIMPACTFUL. COOS COUNTY, THE CASCADES, AREAS
AROUND AND EAST OF LAKESIDE, AND THE WARNER MOUNTAINS ARE EXPECTED
TO SEE BETWEEN 0.25 AND 0.50 INCHES OF RAINFALL. OCCASIONAL SNOW
SHOWERS ARE POSSIBLE OVER THE CASCADES EARLY SUNDAY MORNING, BUT
ACCUMULATION IS NOT EXPECTED. THE UMPQUA VALLEY MAY SEE 0.10
INCHES OF RAINFALL, AND OTHER AREAS WILL HAVE RAINFALL MEASURED IN
THE HUNDRETHS. TEMPERATURES WILL COOL THROUGH THE WEEKEND AS THE
TROUGH MOVES OVER THE AREA.
SEASONAL TEMPERATURES UNDER ZONAL FLOW ALOFT LOOK TO CONTINUE
THROUGH THE WEEK. A COUPLE OF WEAK DISTURBANCES MAY BRIEFLY AFFECT
CONDITIONS FOR CERTAIN LOCATIONS. ON MONDAY, A WEAK FRONT COULD
BRING SOME CLOUDS TO COOS AND EASTERN DOUGLAS COUNTIES. BRIEF
SHOWERS ARE POSSIBLE OVER THESE AREAS ON MONDAY MORNING AND
AFTERNOON, BUT AMOUNTS WILL BE ONE OR TWO HUNDRETHS AT MOST. ON
WEDNESDAY OR THURSDAY, A WEAK DISTURBANCE COULD BRING GUSTY WINDS
AND ISOLATED SHOWERS TO THE NORTHERNMOST BORDER OF THE CWA.
DETERMINISTIC GUIDANCE FOR BOTH THE ECMWF AND THE GFS SHOW SOME
UPPER INSTABILITY PASSING OVER THE AREA, WITH SOME VARIATION IN
TIMING AND STRUCTURE. INDIVIDUAL ENSEMBLE MEMBERS FOR BOTH THE GFS
AND ECMWF ARE SPLIT ON SHOWING THE DISTURBANCE OR NOT, AND THOSE
THAT SHOW IT DO SO WITH SOME VARIATION IN TIMING AND LOCATION.
ZONAL FLOW CONTINUES ON FRIDAY, WITH SOME UNCERTAINTY FOR THE
WEEKEND. WHILE BOTH MODELS SHOW SOME AMOUNT OF UPPER LEVEL RIDGING,
THE STRENGTH AND POSITION OF THE RIDGE VARY. THE GENERAL EXPECTATION
SEEMS TO BE ADDITIONAL WARMING ON SATURDAY AND SUNDAY, BUT LITTLE
OVERALL CONSENSUS ON HOW WARM NEXT WEEKEND WILL BE. NBM
PROBABILISTIC GUIDANCE ECHOS THIS UNCERTAINTY, WITH DAYTIME HIGHS
FORECAST TO BE FROM SEASONAL TEMPERATURES TO 10 DEGREES ABOVE ON
NEXT SUNDAY. -TAD
AVIATION...17/00Z TAFS...CONDITIONS ARE VFR EARLY THIS EVENING WITH
AREAS OF LOCAL TERRAIN OBSCURATION. AN APPROACHING FRONT WILL
PRODUCE THICKENING CLOUDS ACROSS THE AREA THIS EVENING. LIGHT RAIN
WILL DEVELOP AT THE COAST WITH A MIX OF IFR AND MVFR EXPECTED AROUND
03Z, AND CONTINUING INTO SATURDAY MORNING.
MEANTIME, CLOUDS AND SHOWERS WILL ALSO SPREAD INLAND. INLAND
CEILINGS WILL MAINLY BE VFR, BUT AREAS OF MVFR AND MOUNTAIN
OBSCURATION ARE ALSO EXPECTED LATE TONIGHT INTO SATURDAY MORNING.
ALSO, THERE IS A SLIGHT CHANCE OF THUNDERSTORMS LATE TONIGHT THROUGH
SATURDAY FOR LAKE COUNTY AND EASTERN MODOC COUNTY, INCLUDING
LAKEVIEW. THIS RISK WILL REACH A PEAK DURING SATURDAY AFTERNOON OVER
THE WARNER MOUNTAINS.
GENERALLY, SOME LIFTING OF CEILINGS IS EXPECTED DURING SATURDAY, BUT
SHOWERS WILL CONTINUE AND IMPROVEMENT WILL BE MINOR. SHOWERS WILL
TAPER OFF INLAND LATER SATURDAY EVENING, BUT PERSIST AT THE COAST.
-DW
MARINE....UPDATED 200 PM FRIDAY, MAY 16, 2025...A TROUGH WILL
PRODUCE LIGHT SHOWERS WITH MODERATE WINDS AND MODERATE SWELL
DOMINATED SEAS TONIGHT THROUGH SUNDAY MORNING. NORTHWEST WINDS WILL
BE STRONGEST SATURDAY EVENING SOUTH OF BROOKINGS. ANOTHER SEASONABLE
SYSTEM WILL FOLLOW ON MONDAY WITH WINDS VEERING FROM SOUTH TO
NORTHWEST. NORTHERLY WINDS WILL INCREASE ON TUESDAY FROM THE BRIEF
DEVELOPMENT OF A THERMAL TROUGH NEAR SHORE. MEANTIME, BUILDING SEAS
ON TUESDAY MAY POSSIBLY BECOMING HIGH AND STEEP WITH THE COMBINATION
OF THE HIGHER WIND WAVES AND A BUILDING WEST-NORTHWEST SWELL AT 13
SECONDS. CONDITIONS ARE LIKELY TO IMPROVE SLIGHTLY ON WEDNESDAY.
-DW
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
TAD/ANH/DW
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