358
FXUS66 KMFR 201039
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
339 AM PDT TUE MAY 20 2025
DISCUSSION
ZONAL FLOW REMAINS OVER THE AREA TODAY INTO TONIGHT.
SATELLITE IMAGE SHOWS THE BULK OF THE CLOUD COVER ALONG AND WEST OF
THE CASCADES. CLOUD COVER IS EXPECTED TO GRADUALLY DIMINISH LATER IN
THE MORNING WITH MOSTLY CLEAR SKIES IN THE AFTERNOON. IT WILL BE DRY
TODAY THROUGH WEDNESDAY, WITH WEAK UPPER RIDGING BUILDS IN TONIGHT
THROUGH WEDNESDAY. THE UPPER RIDGING WILL RESULT IN MILDER
TEMPERATURES FOR THE INTERIOR WEDNESDAY.
A WEAK UPPER TROUGH WILL MOVE IN WEDNESDAY NIGHT INTO EARLY THURSDAY
MORNING AND COULD BRING A FEW SHOWERS OVER THE NORTHERN PART OF THE
FORECAST AREA. THE UPPER TROUGH WILL MOVE EAST THURSDAY MORNING WITH
WEAK RIDGING BUILDING INTO THE AREA. OTHER THAN A SLIGHT CHANCE OF
SHOWERS OVER THE NORTHERN CASCADES THURSDAY MORNING, IT WILL BE DRY.
ANOTHER WEAK UPPER TROUGH WILL MOVE INTO THE AREA LATER THURSDAY
NIGHT INTO FRIDAY6 MORNING, BUT THIS ISN'T EXPECTED TO HAVE MUCH, IF
ANY AFFECT ON THE WEATHER. SOME OF THE GUIDANCE SUGGEST CONVECTIVE
SHOWERS COULD BREAK OUT EAST OF THE CASCADES FRIDAY AFTERNOON.
HOWEVER, BY THEN THE TROUGH AXIS WILL BE JUST EAST OF THE AREA WITH
THE BEST DYNAMICS SOUTHEAST OFTHE FORECAST AREA. FOR NOW HAVE KEPT
IN A SLIGHT CHANCE OF SHOWERS, BUT WOULD NOT BE SURPRISED IF THE
BEST CHANCE FOR SHOWERS END UP SOUTHEAST OF THE FORECAST AREA.
INSTABILITY PARAMETERS SUGGEST IT WON'T BE UNSTABLE ENOUGH FOR
THUNDERSTORMS FRIDAY AFTERNOON.
THERE'S GOOD AGREEMENT WITH UPPER RIDGING REMAINING A PLAY MAKER FOR
THE FIRST HALF OF THE WEEKEND WITH CONTINUED DRY AND WARMER WEATHER
FOR THE INTERIOR.
THE OPERATIONAL MODELS HAVE COME INTO BETTER AGREEMENT WITH THE
GENERAL CONSENSUS SHOWING THE UPPER RIDGE REMAINING IN PLACE THROUGH
THE HOLIDAY WEEKEND WITH A SLOWER PROGRESSION OF THE UPPER TROUGH,
WITH THE UPPER TROUGH REMAINING FAR ENOUGH OFFSHORE TO KEEP THE
WEATHER DRY AND WARMER. AS A RESULT WE'LL GO WITH DRY CONDITIONS
WITH WARMER AFTERNOON TEMPERATURES FOR THE INTERIOR THIS WEEKEND
WITH AFTERNOON HIGHS IN THE LOWER 80S FOR THE INTERIOR WESTSIDE
VALLEYS AND UPPER 70S EAST OF THE CASCADES SATURDAY, WITH FURTHER
WARMING SUNDAY WITH LOW TO MID 80S FOR THE INTERIOR WESTSIDE VALLEYS
AND UPPER 70S TO LOW 80S EAST OF THE CASCADES.
THE UPPER TROUGH DOES MOVE EAST TOWARDS THE AREA MEMORIAL DAY, BUT
IT WILL WEAKEN AT THE SAME TINE WHICH MAKES SENSE SINCE IT WILL BE
RUNNING INTO THE UPPER RIDGING. THE WEAKENING OF THE TROUGH WILL
RESULT IN CONTINUED DRY AND WARM WEATHER FOR MEMORIAL DAY.
THE MAJORITY OF THE INDIVIDUAL ECMWF ENSEMBLE MEMBERS ALSO LEAN
TOWARDS A DRY AND SLOWER PROGRESSION OF THE UPPER TROUGH.
ADDITIONALLY, THE MAJORITY OF THE CLUSTER SOLUTIONS FAVOR THE UPPER
RIDGING SOLUTION THROUGH MEMORIAL DAY. -PETRUCELLI
AVIATION...20/12Z TAFS
WHILE LOW TO MID LEVEL CLOUDS WILL BE PRESENT
TONIGHT THROUGH LATE TOMORROW MORNING, VFR CONDITIONS ARE ANTICIPATED
THROUGH THE VALID TAF PERIOD. SKIES WILL GENERALLY CLEAR TOMORROW
EXCEPT FOR AREAS ALONG AND NEAR THE COAST AS WELL AS AREAS AROUND
ROSEBURG, BUT EVEN THESE AREAS WILL SEE GENERALLY THINNING OF THE
CLOUD DECKS. OTHERWISE, TYPICAL DIURNAL BREEZES EXPECTED TOMORROW
AFTERNOON.
MARINE...UPDATED 200 AM TUESDAY, MAY 20, 2025
NORTH WINDS WILL
INCREASE TODAY, AND WILL BE STRONGEST SOUTH OF CAPE BLANCO. NORTH
WINDS ARE EXPECTED TO PERSIST INTO WEDNESDAY EVENING, THEN WILL
DIMINISH WEDNESDAY NIGHT AS A WEAK UPPER TROUGH APPROACHES WEAKENING
THE THERMAL TROUGH. STEEP WEST-NORTHWEST SWELL WILL REMAIN OVER THE
WATERS INTO EARLY THIS EVENING, THEN SEAS WILL DIMINISH TONIGHT.
LIGHT TO MODERATE NORTH WINDS ARE EXPECTED WEDNESDAY NIGHT INTO THE
END OF THE WEEK, BUT WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW
SMALL CRAFT. -PETRUCELLI
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 11 PM PDT
WEDNESDAY FOR PZZ350-356-370-376.
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