063
FXUS66 KMFR 212114
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
214 PM PDT MON OCT 21 2024
SHORT TERM...THROUGH WEDNESDAY NIGHT
THIS MORNING'S RAIN
BROUGHT 0.75" TO 1.00" TO COOS, CURRY AND CENTRAL DOUGLAS
COUNTIES. JOSEPHINE COUNTY SAW ON AVERAGE A QUARTER TO A HALF INCH
AND SIMILAR AMOUNTS WERE RECORDED IN NORTHERN JACKSON COUNTY WITH
LESS THAN A TENTH OF AN INCH FOR THE ROGUE VALLEY. MOST AREAS
HAVE DRIED OUT THIS AFTERNOON WITH A FEW SHOWERS IN COOS AND
DOUGLAS COUNTIES.
THE COLD FRONT HAS BROUGHT COOLER AIR WITH HIGHS THIS AFTERNOON 10-
15 DEGREES COLDER THAN YESTERDAY. TONIGHT'S TEMPERATURES WILL BE
BACK TO NEAR NORMAL WITH MORE 30S AND LOW 40S WEST OF THE CASCADES
AND 20S TO LOW 30S EAST. SOME AREAS IN THE VALLEYS OF SISKIYOU
COUNTY TONIGHT ARE AT RISK OF FROST WITH FORECAST LOWS NEAR 33-36
DEGREES. THE FORECAST HAS BEEN ADJUSTED TO SHOW THE POTENTIAL FOR
PATCHY FROST IN THESE AREAS. CLOUD COVER WILL STICK AROUND AND LOWER
CEILINGS COULD BRING OBSCURATIONS AS IT BANKS ALONG THE CASCADES
BEFORE IT BREAKS UP LATER TONIGHT INTO TOMORROW MORNING.
A COLDER MORNING WILL RETURN THURSDAY MORNING WITH LOWS WEST OF THE
CASCADES IN THE LOW TO MID-30S WITH A 40-60% PROBABILITY OF REACHING
32 IN WESTERN SISKIYOU COUNTY VALLEYS. THERE IS A 60-70% PROBABILITY
TO REACH 36 IN THE ROGUE VALLEY, SO THERE'S A POTENTIAL FOR FROST.
PLEASE SEE THE LONG TERM DISCUSSION WHICH GIVES DETAILS ABOUT THE
RETURN OF RAIN CHANCES. -HERMANSEN
LONG TERM...THURSDAY THROUGH MONDAY, OCT 24-28, 2024
WITH A CLOSED LOW MEANDERING OUT NEAR 36N AND 140W IN THE
PACIFIC EARLY IN THE PERIOD, THE UPPER RIDGE DOWNSTREAM WILL AMPLIFY
SOME ALONG THE WEST COAST THU/FRI, RESULTING IN ANOTHER PERIOD OF
DRY WEATHER. THURSDAY MORNING WILL START CHILLY WITH ANOTHER
WIDESPREAD FROST IN THE WEST SIDE VALLEYS, AND ESPECIALLY SOUTH OF
THE ROGUE-UMPQUA DIVIDE. EVEN THE UMPQUA BASIN COULD SEE
TEMPERATURES CONDUCIVE TO FROST (<=36F) THIS TIME AROUND THOUGH.
RIGHT NOW, GUIDANCE SHOWS A 1 IN 3 (33%) CHANCE THAT TEMPERATURES
DROP TO 36F OR LOWER AT ROSEBURG WITH ODDS JUMPING TO A 2 IN 3 (67%)
CHANCE AT MEDFORD. FREEZING TEMPERATURES ARE LESS LIKELY IN THESE
AREAS, BUT THERE'S A 1 IN 4 (25%) CHANCE AT MEDFORD. WE MAY REQUIRE
FROST/FREEZE PRODUCTS AGAIN AT SOME POINT IN THE NEXT COUPLE OF
DAYS.
WITH THE UPPER RIDGE BUILDING IN, THURSDAY AFTERNOON WILL TURN OUT
SUNNY AND MILDER WITH TEMPERATURES GETTING BACK TO NEAR NORMAL
LEVELS. SW PORTIONS OF THE FORECAST AREA WILL HAVE SOMEWHAT HIGHER
TEMPS DUE TO OFFSHORE NE WINDS AND A THERMAL TROUGH ALONG THE COAST.
WITH HIGH PRESSURE OVERHEAD THURSDAY NIGHT, WE'LL HAVE ANOTHER
NIGHT OF STRONG RIDGE/VALLEY INVERSIONS. COLD AIR WILL POOL IN THE
VALLEYS ONCE AGAIN AND IT COULD BE JUST AS CHILLY AS WEDNESDAY NIGHT
WITH AREAS OF FROST.
AFTER THE COLD MORNING FRIDAY, THE THERMAL TROUGH WILL SHIFT INLAND
AND THE UPPER RIDGE AXIS WILL MOVE EAST OF THE CASCADES. THE CLOSED
LOW OFFSHORE WILL HAVE OPENED UP INTO A TROUGH BY NOW AND WILL
GRADUALLY MAKE ITS WAY TOWARD THE PACNW COAST. WHILE HIGH AND MID
CLOUDS WILL LIKELY INCREASE IN ADVANCE OF THIS SYSTEM, IT WILL ALSO
PROBABLY BE THE WARMEST DAY OF THE PERIOD. GUIDANCE IS SHOWING
WIDESPREAD HIGH TEMPERATURES IN THE LOW TO MID 70S FOR THE VALLEYS
WEST OF THE CASCADES AND HIGHS LARGELY IN THE MID TO UPPER 60S OVER
THE EAST SIDE.
RAIN CHANCES DON'T REALLY INCREASE UNTIL FRIDAY NIGHT WEST OF THE
CASCADES AHEAD OF A WARM FRONT, WITH HIGHEST POPS 20-60% FROM GRANTS
PASS/ROSEBURG WESTWARD (HIGHEST ALONG THE COAST). WITH THE INCREASE
IN CLOUD COVER, FRIDAY NIGHT WON'T BE AS COLD AS PREVIOUS NIGHTS.
AREAS EAST OF THE CASCADES WILL REMAIN DRY. IT SHOULD BE NOTED THAT
MODELS ARE SHOWING A PRETTY GOOD GRADIENT IN ADVANCE OF THE WARM
FRONT, WHICH MAY RESULT IN SOME BREEZY SOUTH WINDS (30-40 MPH PEAK
GUSTS) ESPECIALLY IN THE SHASTA VALLEY AND EAST OF THE CASCADES)
DURING FRIDAY EVENING. SNOW LEVELS WILL ALSO BE WAY HIGH -- UP
AROUND 8000 FEET. MUCH OF THE SUPPORT ALONG THE WARM FRONT WILL RACE
OFF TO THE NORTHEAST SATURDAY, SO WHAT'S LEFT BEHIND IT WILL BE
MOIST LOW-LEVEL ONSHORE FLOW, WITH THE COLD FRONT POISED TO MOVE
ONSHORE. POPS REMAIN HIGHEST NEAR AND WEST OF THE CASCADES (60-80%
CHANCES), BUT ESPECIALLY AT THE COAST. THE COLD FRONT MOVES INLAND
SATURDAY NIGHT AND WEAKENS.
AN ACTIVE WEATHER PATTERN LIKELY CONTINUES SUNDAY INTO MONDAY AS
ANOTHER PACIFIC UPPER LEVEL DISTURBANCE MOVES THROUGH. THIS WILL
BRING A HIGH PROBABILITY OF PRECIPITATION AREA WIDE (60-90% CHANCE),
BUT WITH THE BEST CHANCE FOR MEANINGFUL (WETTING) PRECIPITATION FROM
THE CASCADES WEST. SNOW LEVELS DURING THE TIME PERIOD FALL TO
NEAR 5000 FEET, SO WE'LL BE LOOKING AT A DECENT CHANCE FOR AT
LEAST SOME ACCUMULATING SNOW IN THE MOUNTAINS. -SPILDE
AVIATION...21/18Z TAFS
AS OF 18Z, THE COLD FRONT IS LOCATED
APPROXIMATELY OVER LAKE AND MODOC COUNTIES AND WILL CONTINUE MOVING
EAST AND OUT OF OUR AREA THIS AFTERNOON. VFR TO MVFR CONDITIONS WITH
RESIDUAL SHOWERS ARE LEFT IN ITS WAKE THROUGH THIS EVENING.
SHOWERS WILL GRADUALLY DRY UP THIS EVENING, AND THEN OVERNIGHT THE
FOCUS FOR AVIATION TURNS TO FOG POTENTIAL. GUIDANCE HAS A 40-50%
CHANCE OF IFR CONDITIONS DUE TO CEILING AND AROUND A 30% CHANCE FROM
VISIBILITY, BOTH CENTERED OVER THE UMPQUA BASIN. THE LOCATION MAKES
SENSE, AND THERE IS PLENTY OF SURFACE MOISTURE FOR FOG WEST OF THE
CASCADE CREST, BUT EXPERIENCE SUGGESTS THAT THIS WILL DEPEND ON THE
DEGREE OF CLEARING TONIGHT. FOR NOW, WE HAVE INCLUDED DEGRADED
CONDITIONS IN THE TAF FOR KRBG AND TRENDED THAT WAY IN BOTH KOTH AND
KMFR. KLMT RECEIVED LITTLE RAIN, SO THEY ARE THE LEAST LIKELY TO SEE
ANY DEGRADED CONDITIONS TONIGHT. -WRIGHT
MARINE...UPDATED 200 PM PDT MONDAY, OCTOBER 21, 2024
RELATIVELY
LIGHT WEST WINDS AND PRIMARILY FRESH SWELL DOMINATED SEAS WILL
CONTINUE THROUGH TUESDAY MORNING.
GUSTY NORTH WINDS AND STEEP WIND DRIVEN SEAS RETURN SOUTH OF CAPE
BLANCO FOR TUESDAY AFTERNOON THROUGH TUESDAY NIGHT AS A THERMAL
TROUGH BRIEFLY DEVELOPS. CONDITIONS IMPROVE AGAIN WEDNESDAY, BEFORE
A STRONGER THERMAL TROUGH DEVELOPS FOR THURSDAY. STEEP SEAS ARE
POSSIBLE ACROSS ALL OF THE SOUTHERN OREGON WATERS ON THURSDAY
AFTERNOON AND NIGHT.
ANOTHER BRIEF BREAK IS POSSIBLE FRIDAY BEFORE THE NEXT FRONT
ARRIVES FRIDAY NIGHT INTO SATURDAY. THERE IS A WIDE VARIETY OF
MODEL SOLUTIONS REGARDING THE STRENGTH AND TIMING OF THE FRONT,
BUT STEEP TO VERY STEEP SEAS AND GALES ARE POSSIBLE. -WRIGHT/DW
MFR WATCHES/WARNINGS/ADVISORIES
OR...CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FROM 2 PM TUESDAY TO 2
AM PDT WEDNESDAY FOR PZZ356-376.
ANH/MAS/TRW
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