520
FXUS66 KMFR 052356
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
456 PM PDT TUE MAY 5 2026
DISCUSSION
UPDATED AVIATION DISCUSSION.
AVIATION...06/00Z TAFS
ISOLATED SHOWERS OVER THE EAST SIDE
THIS EVENING WILL DISSIPATE AS THE SUN SETS WITH VFR PREVAILING
THROUGH THE NEXT 24 HOURS. A FAIRLY DEEP MARINE LAYER EXISTS ALONG
THE COAST THIS EVENING WITH MVFR CEILINGS AROUND 1500 FT. THESE
CEILINGS BRIEFLY BROKE AT NORTH BEND THIS AFTERNOON, BUT WILL
RETURN TONIGHT AND COULD LOWER TO IFR AT TIMES AS WELL (IN THE
500-1000 FT RANGE). CEILINGS ARE EXPECTED TO FILL INTO THE UMPQUA
BASIN AGAIN LATER TONIGHT, SO MVFR IS LIKELY TO RETURN TO ROSEBURG
AND LAST THROUGH MOST OF THE MORNING BEFORE BREAKING TO VFR AFTER
19Z. MEDFORD SHOULD REMAIN VFR, THOUGH PATCHES OF STRATUS COULD
SPILL THROUGH GAPS IN THE UMPQUA DIVIDE TO NEAR GRANTS PASS.
STRATUS IMPACTING THE NORTHERN PORTIONS OF THE SACRAMENTO VALLEY
(NEAR REDDING) COULD EXPAND INTO AREAS NEAR AND JUST
SOUTH/SOUTHEAST OF MT. SHASTA (FAR SE SISKIYOU/SW MODOC COUNTIES)
TONIGHT/WED MORNING BEFORE BREAKING TO VFR AGAIN. -SPILDE
PREV DISCUSSION
/ISSUED 149 PM PDT TUE MAY 5 2026/
DISCUSSION...
A STRONG MARINE LAYER IS RETREATING THIS AFTERNOON WITH PLENTY OF
CUMULUS BUILD UP EAST OF THE CASCADES. THE LATEST HIGH RESOLUTION
ENSEMBLE FORECAST SYSTEM RUNS SHOWS A VERY LOW RISK OF
THUNDERSTORMS EAST OF THE CASCADES. ALTHOUGH NOT IMPOSSIBLE, THE
ODDS ARE UNDER 5%, MOSTLY DUE TO LACK OF MOISTURE. FORECAST
SOUNDINGS DO SHOW DEEP MIXING WITH SURFACE AIR PARCELS MEETING
THE LEVEL OF FREE CONVECTION HEIGHT AROUND 8000 FEET. HOWEVER,
THE AREA OF CAPE AND CONVECTION SHOULD BE VERY SHALLOW AND WARMER
THAN -10C, SO LIGHTNING IS NOT ANTICIPATED.
BY TONIGHT, WE'RE LOOKING AT ANOTHER MARINE LAYER IN THE UMPQUA
BASIN, PERHAPS WITH SOME PATCHY FOG ALONG THE COAST AND IN A FEW
OF THE RIVER VALLEYS. GIVEN THE TIME OF YEAR, THE CHANCE OF FOG IS
REALLY SLIM IN SOME OF THE VALLEYS FARTHER INLAND.
OTHERWISE, THE MAIN STORY FOR THE REST OF THE WEEK WILL BE
TEMPERATURES WARMER THAN NORMAL. HIGHS IN MEDFORD WILL BE PUSHING
INTO THE MID 80S AND 10 TO 15 DEGREES WARMER THAN NORMAL, YET
WELL SHORT OF RECORD HIGHS FOR EARLY MAY. 850MB AND 700MB
TEMPERATURES WILL BE IN THE 97TH PERCENTILE FOR LATE APRIL AND
EARLY MAY BASED OFF OF NAEFS FORECAST DATA. OVERALL, THIS DRIVES
HOME THE POINT WE'RE LOOKING AT ABOVE NORMAL TEMPERATURES UNTIL
THURSDAY.
BY FRIDAY, A SHORTWAVE WILL BREAK DOWN THE RIDGE AND WE'LL SEE
TEMPERATURES TREND 5 DEGREES COOLER COMPARED TO THURSDAY. THE
PROBABILITY OF PRECIPITATION FORECAST IS NEAR 0 PERCENT AS THIS
SHORT WAVE MOVES ON SHORE, SO IT'S LOOKING PRETTY DRY FRIDAY INTO
EARLY NEXT WEEK.
THE RIDGE BUILDS BACK IN AROUND THE WEEKEND WITH SOME SIGNS OF A
THERMAL TROUGH BUILDING ALONG THE COAST. THE WARMER THAN NORMAL
TEMPERATURES WILL LIKELY CONTINUE WITH SOME DRIER AIR IN PLACE FOR
THIS WEEKEND.
-SMITH
AVIATION (18 TAFS)...
A STRONG MARINE PUSH ALL THE WAY TO THE CASCADES THIS MORNING IS
STARTING TO ERODE TOWARDS THE COAST, WITH MVFR/IFR AND TERRAIN
OBSCURATIONS ALSO RETREATING TO THE WEST. EXPECTING CONDITIONS TO
CLEAR UP THIS AFTERNOON FOR INLAND SITES, BUT NOT EXPECTING TOO MUCH
RELIEF FOR NORTH BEND. THERE IS A LOW END CHANCE FOR ISOLATED
SHOWERS/THUNDERSTORMS TODAY WITH KLMT HAVING THE RELATIVELY HIGHER
CHANCE TO SEE THIS THREAT. THE MARINE LAYER IS EXPECTED TO PUSH BACK
IN TONIGHT, BUT NOT AS FAR, WITH ADDITIONAL MVFR/IFR CEILINGS AND
VISIBILITY THROUGH THE COASTAL MOUNTAINS AND INTO THE UMPQUA BASIN
AND ROSEBURG, AND PERHAPS PORTIONS OF THE ROGUE BASIN, WITH A LOW
CHANCE OF IMPACTS AT MEDFORD.
MARINE...UPDATED 1200 PM PDT TUESDAY, MAY 5, 2026....AN EXTENDED
PERIOD OF RELATIVELY CALM CONDITIONS WILL CONTINUE THROUGH WEDNESDAY
NIGHT, WITH WEST-NORTHWEST SWELL DOMINATED SEAS LIKELY REMAINING
BELOW 8 FT. NORTH WINDS AND STEEP SEAS BRIEFLY INCREASE THURSDAY
SOUTH OF CAPE BLANCO, THEN DIMINISH AGAIN BY THURSDAY NIGHT. A
THERMAL TROUGH WILL DEVELOP SATURDAY, RESULTING IN GUSTY NORTH WINDS
AND STEEP SEAS THROUGH EARLY NEXT WEEK.
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
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