456
FXUS66 KMFR 202140
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
240 PM PDT SUN OCT 20 2024
SHORT TERM...SUNDAY NIGHT THROUGH WEDNESDAY NIGHT
AFTERNOON
TEMPERATURES TODAY WILL REMAIN ABOVE SEASONAL AVERAGES UNDER THE
LAST INFLUENCES OF AN UPPER LEVEL RIDGE. WEST SIDE VALLEYS ARE
EXPECTED TO REACH THE MID 70S, WHILE AREAS TO THE EAST WILL BE IN
THE MID 60S TO LOW 70S.
A COLD FRONT WILL APPROACH THE AREA THIS EVENING, BRINGING RAINFALL
ACROSS THE OREGON COAST TONIGHT AND THROUGH LATE MONDAY MORNING.
FORECAST AMOUNTS REMAIN IN THE 0.75 TO 1 INCH RANGE FOR THE COAST.
INLAND COOS AND CURRY COUNTIES COULD GET MORE THAN HALF AN INCH OF
RAINFALL, WHILE DOUGLAS COUNTY WILL GET A LITTLE LESS. JOSEPHINE AND
JACKSON COUNTIES ARE EXPECTED TO GET 0.2 INCHES OR LESS, AND A FEW
HUNDRETHS ARE POSSIBLE IN KLAMATH AND EASTERN LAKE COUNTIES.
OVERALL, RAINFALL TOTALS ARE NORMAL FOR THE AREA. THERE WILL BE
SINGLE-DIGIT THUNDERSTORM CHANCES OVER WEST SIDE AREAS ON MONDAY
MORNING SO WIDESPREAD ACTIVITY IS NOT EXPECTED.
A RANGE OF RAINFALL AMOUNTS REMAINS IN PROBABILISTIC FORECASTS,
DEPENDING ON HOW THE FRONT MOVES OVER THE AREA. FOR EXAMPLE, THE
INTERQUARTILE RANGE OF THE NBM CONTINUES TO AN INTERQUARTILE RANGE
FOR BROOKINGS OF 0.75 TO 1.5 INCHES THROUGH MONDAY. MEDFORD COULD
GET ANYWHERE BETWEEN NOTHING AND 0.3 INCHES. THE MAIN CONCLUSION
FROM THIS IS THAT SHOWERS MAY BE HEAVIER THAN THE DETERMINISTIC
FORECAST IN SOME AREAS. HIGHER RAINFALL AMOUNTS WOULDN'T POSE ANY
WIDESPREAD HAZARDS, BUT MAY MAKE TRAVEL DIFFICULT IN LOCALIZED AREAS.
FOR NON-RAINFALL CONDITIONS ON MONDAY, SNOWFALL IS NOT A CONCERN
WITH THIS FRONT AS CURRENT HIGH SNOW LEVELS THAT WON'T START TO FALL
UNTIL AFTER PRECIPITATION HAS TRAILED OFF. WINDS WILL PICK UP IN THE
SOUTHERN SHASTA VALLEY EARLY MONDAY MORNING AND THE EAST OF THE
CASCADES ON MONDAY AFTERNOON AND EVENING, BUT WILL REMAIN SAFELY
UNDER ADVISORY LEVELS.
A DRY PERIOD WILL FOLLOW THE FRONT AND CONTINUE THROUGH MOST OF THE
WEEK. SEASONAL TEMPERATURES ARE EXPECTED ACROSS THE AREA ON MONDAY
AND TUESDAY, WITH WARMING ON WEDNESDAY AND THURSDAY BRINGING LOW 70S
WEST OF THE CASCADES AND MID TO HIGH 60S TO THE EAST. THERE ARE
SLIGHT CHANCES (15-25%) FOR FOG IN LOW LYING AREAS ON MONDAY NIGHT
INTO TUESDAY MORNING AND LOWER CHANCES ON WEDNESDAY MORNING. -TAD
LONG TERM
A HIGH PRESSURE RIDGE WILL REMAIN IN PLACE ON
THURSDAY. MEANWHILE MODELS SHOW GOOD AGREEMENT WITH A WEAK LOW
APPROACHING FROM THE WEST LATE THURSDAY INTO FRIDAY. THIS LOW IS
EXPECTED TO WEAKEN AS IT TRACKS NORTHWARD ALONG THE OREGON COAST
FRIDAY INTO EARLY SATURDAY. MODEL SOLUTIONS VARY ON THE EXACT
TIMING AND TRACK THOUGH. THIS WILL PLAY A ROLE IN HOW MUCH
RAINFALL SPREADS INLAND FROM THE COAST AS THE LOW MOVES NORTHWARD.
GIVEN THESE DIFFERENCES, CONFIDENCE IS LOW ON THE DETAILS OF HOW
MUCH PRECIPITATION IT MAY BRING. THE MAJORITY OF THE MODELS
INDICATE RAINFALL NEAR THE COAST AND INLAND INTO PORTIONS OF THE
AREA FROM THE CASCADES WEST WITH LOWER CHANCES FOR RAIN EAST OF
THE CASCADES(15-30%). OVERALL, THIS SYSTEM DOESN'T LOOK IMPACTFUL
AS ALMOST ALL THE MODEL SIMULATIONS HAVE A LOW AROUND 990 TO 1000
MILLIBARS AND SOME MEMBERS DO NOT HAVE A DISTINGUISHABLE LOW
CENTER. ADDITIONALLY, WE WILL BE UNDER SOUTHWEST FLOW WHEN THIS
WEATHER HITS BETWEEN THURSDAY NIGHT INTO SATURDAY, SO SNOW LEVELS
WILL LIKELY REMAIN ON THE HIGH SIDE(7000-8000 FEET).
THEREAFTER, WE MAY SHIFT TO A COOLER AND WETTER PATTERN. MODELS AND
ENSEMBLES SHOW A LOW PRESSURE SYSTEM IN THE GULF OF ALASKA BRING A
FRONT INTO THE REGION NEXT WEEKEND. -CC
AVIATION (18Z TAFS)
MARINE STRATUS REMAINS PARKED NEAR THE COAST,
BUT AN APPROACHING FRONT SHOULD HELP MIX SOME OF IT OUT THROUGH THE
AFTERNOON. INLAND, VFR CONDITIONS WILL CONTINUE THROUGH TODAY. THE
FRONT WILL BRING RAIN, MODERATE AT TIMES, TO THE COAST THIS EVENING
AND OVERNIGHT. RAIN WITH VFR TO OCCASIONAL MVFR CEILINGS WILL
OVERSPREAD AREAS FROM THE CASCADE CREST WEST TONIGHT. EAST SIDE
LOCATIONS WILL LIKELY STAY VFR BUT WITH SPOTTY SHOWERS AND BRIEF
REDUCTIONS TO CONDITIONS LATE TONIGHT INTO MONDAY MORNING. WINDS
WILL BECOME SOUTHERLY AT MOST LOCATIONS AS THE FRONT APPROACHES, BUT
SPEEDS WILL REMAIN FAIRLY LIGHT. -WRIGHT
MARINE (UPDATED 200 PM)
A COLD FRONT IS APPROACHING THE WATERS
FROM THE WEST THIS AFTERNOON. CONDITIONS GENERALLY REMAIN JUST BELOW
SMALL CRAFT ADVISORY THRESHOLDS, BUT SOUTH WINDS GUSTING INTO THE 25-
27 KNOT RANGE WILL CONTINUE AHEAD OF THE FRONT, ESPECIALLY NORTH OF
CAPE BLANCO. SEAS WILL ALSO REMAIN ELEVATED BUT GENERALLY SUB SMALL
CRAFT LEVELS AS THE FRONT APPROACHES. THE FRONT MOVES THROUGH LATE
THIS EVENING AND THEN ONSHORE TONIGHT BRINGING RAIN WITH DIMINISHING
WINDS AND SEAS BEHIND IT. CONDITIONS IMPROVE BRIEFLY MONDAY, BUT A
THERMAL TROUGH DEVELOPS ALONG THE COAST TUESDAY THAT IS LIKELY BRING
TO BRING AT LEAST SMALL CRAFT ADVISORY LEVEL NORTH WINDS AND WIND
DRIVEN SEAS LATER TUESDAY THROUGH THURSDAY. -WRIGHT
MFR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
TAD/CC/TRW
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