424
FXUS66 KMFR 211631
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
931 AM PDT SAT SEP 21 2019
UPDATE
LOW CLOUDS AND FOG ARE COMMON IN THE WEST SIDE VALLEYS
THIS MORNING, AND ARE PRESENT, BUT NOT AS WIDESPREAD, IN THE
VALLEYS EAST OF THE CASCADES AS WELL. THESE AREAS SHOULD BURN OFF
QUICKLY THIS MORNING, AND SKIES SHOULD BE MOSTLY CLEAR THIS
AFTERNOON. HAVE ADJUSTED THE FORECAST THIS MORNING TO ACCOUNT FOR
THE LOW CLOUDS, BUT NO OTHER UPDATES ARE NEEDED. FOR THE REST OF
THE FORECAST, INCLUDING THE UPCOMING RAIN TOMORROW, SEE THE
PREVIOUS FORECAST BELOW. -BPN
AVIATION...FOR THE 21/12Z TAFS
AREAS OF MVFR/IFR/LIFR LOW CLOUDS
AND FOG CAN BE EXPECTED THIS MORNING ALONG THE COAST FROM CAPE
BLANCO NORTHWARD, AND IN THE UMPQUA VALLEY. ALSO, LATE NIGHT INTO
EARLY MORNING PATCHY FOG IS POSSIBLE AGAIN IN THE KLAMATH BASIN.
AFTER 15Z, THE STRATUS WILL BEGIN TO DIMINISH WITH VFR EXPECTED
ACROSS THE AREA FROM LATE MORNING INTO SATURDAY EVENING. SOME LOW
CLOUDS MAY RETURN AGAIN LATE SATURDAY NIGHT. -SPILDE
MARINE...UPDATED 853 AM PDT SATURDAY 21 SEPTEMBER 2019
HIGH
PRESSURE OFFSHORE AND A THERMAL TROUGH ALONG THE COAST WILL PERSIST
THROUGH THIS EVENING. GUSTY NORTH WINDS WILL LEAD TO STEEP SEAS
HAZARDOUS TO SMALL CRAFT SOUTH OF PORT ORFORD.
CONDITIONS IMPROVE TONIGHT INTO SUNDAY AS THE THERMAL TROUGH PATTERN
GETS INTERRUPTED AHEAD OF THE NEXT FRONT. THE FRONT IS EXPECTED
SUNDAY. WINDS WILL BRIEFLY TURN SOUTHERLY AHEAD OF THIS FRONT, BUT
ARE EXPECTED TO REMAIN BELOW ADVISORY LEVEL. EXPECT A PERIOD OF
SHOWERS AND THE POSSIBILITY OF THUNDERSTORMS AS THE FRONT MOVES
INLAND SUNDAY AFTERNOON AND EVENING. SEAS WILL ALSO BUILD WITH THIS
FRONTAL PASSAGE AS NORTHWEST SWELL MOVES INTO THE WATERS. MONDAY
INTO WEDNESDAY, THE THERMAL TROUGH QUICKLY REDEVELOPS, BRINGING THE
RETURN OF NORTHERLY WINDS (POSSIBLE GALES) AND STEEP WIND DRIVEN
SEAS, ESPECIALLY SOUTH OF CAPE BLANCO. THE NEXT DISTURBANCE IS
EXPECTED AROUND THURSDAY AND MAY BE ACCOMPANIED BY A BUILDING, LARGE
NORTHWEST SWELL. -SPILDE/SVEN
PREV DISCUSSION
/ISSUED 330 AM PDT SAT SEP 21 2019/
DISCUSSION...
SATELLITE SHOWS FOG AND STRATUS FORMING OVER THE UMPQUA VALLEY AND
THE CENTRAL COAST THIS MORNING. IN FACT, NORTH BEND IS CURRENTLY
REPORTING 1/4 MILE VISIBILITY AND FOG. IN ADDITION, SOME UPPER
LEVEL CLOUDS ARE MOVING THROUGH EAST OF THE CASCADES. WITH THE
LIGHT WINDS, COOL TEMPERATURES AND RECENT RAINFALL, WE STILL FEEL
PATCHY FROST WILL FORM LATER THIS MORNING IN VALLEYS EAST OF THE
CASCADES. AS FOR THE REMAINDER OF THE DAY, TEMPERATURES WILL PUSH
INTO THE LOWER 70'S AND THE LOWER 80'S IN SOME OF THE VALLEYS WEST
OF THE CASCADES.
SUNDAY WILL TURN WETTER WITH A LOW AND WEAK COLD FRONT APPROACHING
THE COAST. IT LOOKS LIKE THE COLD FRONT WILL MOVE ONSHORE DURING
THE LATE MORNING HOURS. THE KEY TALKING POINT HERE IS THAT MOST OF
THE RAIN WILL PROBABLY FALL IN THE AFTERNOON FOR AREAS FARTHER
INLAND. FOR AREAS EAST OF THE CASCADES, SUNDAY SHOULD BE PRETTY
NICE BEFORE THE RAIN FINALLY MOVES DURING THE LATE AFTERNOON AND
EARLY EVENING. WE'LL SEE AROUND 0.1 TO 0.25 INCHES OF RAIN WITH
THE HIGHER TOTALS LOCATED FARTHER NORTH IN THE UMPQUA VALLEY AND
ALONG THE COASTAL RANGE. THERE IS STILL A SLIGHT CHANCE FOR SOME
THUNDERSTORMS ON SUNDAY AS THIS LOW MOVES THROUGH. POTENTIAL
INSTABILITY WILL BE PRETTY LOW, SO LIGHTNING ACTIVITY SHOULD BE
LOW AND LIMITED ACROSS THE REGION.
AFTER THIS LOW PASSES THROUGH, WE'LL SEE HIGH PRESSURE AND QUIET
WEATHER FOR THE START OF THE WORK WEEK UNTIL ROUGHLY THURSDAY.
SOME MODEL GUIDANCE SUGGESTS THIS IS WHEN WE'LL HAVE A SLIGHT
CHANCE FOR SOME SHOWERS MOVING THROUGH THE REGION. THE BEST CHANCE
WILL IN FACT BE AROUND FRIDAY WHEN ALL THE MODELS SHOW A DEEP LOW
OVER OREGON. THE OTHER NOTEWORTHY FEATURE HERE IS SNOW LEVELS
WILL BE AROUND 5500 TO 6500 FEET WHEN THIS LOW HOVERS OVER THE
REGION. THEREFORE, MT ASHLAND AND CRATER LAKE WILL LIKELY SEE SOME
ACCUMULATING SNOW NEXT WEEKEND. JUST ANOTHER SIGN THAT FALL IS
RIGHT AROUND THE CORNER.
-SMITH
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 5 AM PDT SUNDAY FOR PZZ356-376.
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