576
FXUS66 KMFR 181835
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
1134 AM PDT FRI OCT 18 2024
UPDATED AVIATION SECTION
DISCUSSION
THE FORECAST IS ON TRACK FOR TODAY. AN EXISTING
FREEZE WARNING WILL EXPIRE AT 9 AM PDT. THERE ARE SLIGHT TO
MODERATE CHANCES OF FROST CONDITIONS RETURNING TO CERTAIN WEST
SIDE VALLEYS TONIGHT. THE ROGUE, APPLEGATE, AND ILLINOIS VALLEYS HAVE
LOW (5-25%) CHANCES OF SEEING FROST CONDITIONS TONIGHT. THE
SCOTT, SHASTA, LOWER KLAMATH RIVER VALLEY, AND THE MOUNT SHASTA
AREA HAVE LOW TO MODERATE (20-50%) OF SEEING FROST CONDITIONS.
UNLESS GUIDANCE SHOWS ANY SIGNIFICANT CHANGES, THERE WILL BE NO
HAZARDS ISSUED FOR TONIGHT.
PLEASE SEE THE PREVIOUS DISCUSSION FOR MORE DETAILS ON THE SHORT-
AND LONG-TERM FORECASTS. -TAD
AVIATION...18/18Z TAFS
VFR WITH LIGHT, VARIABLE WINDS WILL
PREVAIL OVER THE AREA FOR THE NEXT 24 HOURS. MID AND HIGH CLOUDS
WILL DRIFT OVER MAINLY NORTHERN AND WESTERN SECTIONS AT TIMES. THESE
CLOUDS WILL LOWER SOME TONIGHT ALONG THE COAST, PERHAPS TO MVFR AT
NORTH BEND. ALSO, PATCHY FOG COULD REDEVELOP IN SOME TYPICAL WEST A
SIDE VALLEY LOCATIONS, BUT PROBABLY NOT AT THE TERMINALS. -SPILDE
MARINE (UPDATED 300 AM)
STEEP NORTHWEST SEAS ARE BRINGING CONDITIONS HAZARDOUS TO SMALLER
CRAFTS THROUGH THIS MORNING. IMPROVING CONDITIONS ARE EXPECTED LATER
TODAY AND THROUGH THE WEEKEND. HOWEVER, STEEP SEAS ARE LIKELY TO
RETURN THROUGH EARLY PARTS OF NEXT WEEK.
-GUERRERO
PREV DISCUSSION
/ISSUED 305 AM PDT FRI OCT 18 2024/
SHORT TERM...
AN UPPER LEVEL RIDGE REMAINS IN PLACE THIS MORNING WITH PLENTY OF
CLEAR SKIES OVER HEAD. WE'RE ANTICIPATING MANY LOCATIONS TO HIT
THE FREEZING MARK, ALTHOUGH IT MAY BE A LITTLE TO WARM IN SOME
OTHER LOCATIONS LIKE MEDFORD. THE PROBABILITY OF FREEZING THIS
MORNING IS ABOUT 35% HERE IN MEDFORD, ALTHOUGH THOSE PROBABILITIES
ARE NEAR 100% IN THE MOUNT SHASTA CITY AND LOCATIONS IN THE SCOTT
VALLEY IN NORTHERN CALIFORNIA. IN ANY CASE, IT WILL BE ONE THE
COOLEST MORNINGS FOR MANY LOCATIONS THIS FALL.
A WARM FRONT WILL BE APPROACHING FROM THE WEST WITH INCREASING
HIGH CLOUDS INTO THE LATE AFTERNOON AND EVENING HOURS, ESPECIALLY
FOR LOCATIONS FARTHER TO THE NORTH. EVEN WITH A FRONT PUSHING ON
SHORE, WE'RE NOT ANTICIPATING MUCH PRECIPITATION HERE IN SOUTHERN
OREGON OR NORTHERN CALIFORNIA. MOST OF THAT WILL FALL TO OUR
NORTH. HOWEVER, WE SHOULD SEE WARMING TEMPERATURES, WITH HIGH
TEMPERATURES TRENDING ABOUT 10 DEGREES WARMER FROM FRIDAY INTO
SATURDAY. DEW POINTS ALSO TREND ABOUT 20 DEGREES HIGHER, WHICH
REALLY TELLS THE STORY OF HOW DRY AND COLD IT IS THIS FRIDAY
MORNING.
FINALLY BY SATURDAY, WE'RE UNDER PERSISTENT SOUTH WEST TO
WESTERLY FLOW. AN UPPER LEVEL RIDGE ALSO APPEARS TO BE PRESENT
OVER MOST OF NORTHERN CALIFORNIA. IT ALSO LOOKS LIKE AN
ATMOSPHERIC RIVER IS HITTING THE STATE OF WASHINGTON WITH OUR
LOCATION NOT SEEING SUFFICIENT SYNOPTIC LIFT FOR SOME
PRECIPITATION. OVERALL THE NEXT 48 HOURS SHOULD BE PRETTY TYPICAL
FALL WEATHER FOR MID OCTOBER WITH HIGHS JUMPING BACK INTO THE MID
70'S FOR LOCATIONS WEST OF THE CASCADES AND UPPER 60'S EAST OF THE
CASCADES. THE ONLY IMPACTS IN THE NEAR TERM ARE FREEZING
TEMPERATURES KILLING OFF SOME SENSITIVE PLANTS THIS MORNING.
-SMITH
LONG TERM...SUNDAY THROUGH THURSDAY, OCT 20-24, 2024 (AND
BEYOND)...
THE UPPER RIDGE AXIS BRINGING THE DRY WEATHER TO THE AREA WILL SHIFT
TO THE SOUTH AND EAST OF THE CASCADES ON SUNDAY AS THE NEXT PACIFIC
DISTURBANCE, AN UPPER TROUGH AND COLD FRONT, APPROACHES THE PACNW
COAST. EXPECT INCREASING AMOUNTS OF MOSTLY HIGH/MID LEVEL CLOUDS,
BUT MOST AREAS WILL ESCAPE WITH ANOTHER WARM, DRY DAY WITH
TEMPERATURES AVERAGING ABOUT 5-10F ABOVE NORMAL. THIS PUTS MEDFORD
AND MOST OTHER WEST SIDE VALLEY LOCATIONS IN THE LOW TO MID 70S.
EAST SIDE AREAS ARE LIKELY TO BE SUNNIEST AND HAVE THE LARGEST
TEMPERATURE DEPARTURE FROM NORMAL WITH HIGHS IN THE UPPER 60S TO LOW
70S (EXCEPT NEAR 80F IN THE LOWER KLAMATH RIVER VALLEY FROM HAPPY
CAMP SOUTHWARD). NORMALS THIS TIME OF YEAR ARE IN THE UPPER 60S FOR
MEDFORD AND IN THE LOW/MID 60S FOR NORTH BEND, KLAMATH FALLS, YREKA,
ALTURAS, MT. SHASTA AND ROSEBURG.
RAIN CHANCES INCREASE WEST OF THE ILLINOIS VALLEY/NW OF THE ROGUE-
UMPQUA DIVIDE, AND ESPECIALLY COASTAL AREAS SUNDAY AFTERNOON. THE
FRONT MOVES ONSHORE AND INLAND SUNDAY NIGHT INTO MONDAY MORNING WITH
A HIGH PROBABILITY OF RAIN (60-90%) FROM THE CASCADES WEST DURING
THIS PERIOD. HOWEVER, MODELS ARE CONSISTENTLY SHOWING THE MID-
UPPER FLOW BECOMING PARALLEL TO THE FRONT AND UPPER SUPPORT
LIFTING TO THE NORTH. AS SUCH, MOST PRECIPITATION WILL FIZZLE
BEFORE REACHING OUR FAR SE ZONES (FAR SOUTHERN LAKE, MODOC AND
EASTERN SISKIYOU COUNTIES) MONDAY AFTERNOON. SLIGHT COOLING SHOULD
ACCOMPANY THIS FRONT, BUT TEMPERATURE DIFFERENCES ALONG IT AREN'T
THAT DRAMATIC. WE AREN'T EXPECTING SNOW LEVELS TO DROP MUCH BELOW
6500 FEET FOR THIS ONE. AS SUCH, ONLY THE HIGHEST MOUNTAINS FROM
AROUND CRATER LAKE NORTHWARD COULD SEE SOME WET SNOW MIX WITH THE
RAIN.
PRECIPITATION LARGELY ENDS EVERYWHERE BY LATE MONDAY
AFTERNOON/EVENING. MEANWHILE, ENERGY ON THE BACK SIDE OF THE TROUGH
WILL GET PINCHED OFF FROM THE MAIN JET AND FORM A CLOSED LOW WELL
OFFSHORE OUT OVER THE OCEAN (OUT BETWEEN 135 AND 145W) TUE-WED OF
NEXT WEEK. THIS SHOULD ALLOW THE UPPER RIDGE TO REBUILD IN FRONT OF
IT RESULTING IN ANOTHER DRY, MILD PERIOD THAT WILL PERSIST AT LEAST
INTO THURSDAY. THE MINORITY OF SOLUTIONS YESTERDAY SHOWING PART OF
THE TROUGH LINGERING NEAR THE PACNW WEDNESDAY HAVE ALL BUT
DISAPPEARED, SO RAIN CHANCES ARE MINIMAL THEN (MOSTLY LESS THAN
10%). TEMPERATURES DURING THIS PERIOD ARE LIKELY TO BE A FEW TO
SEVERAL DEGREES ABOVE NORMAL ONCE AGAIN.
THE PATTERN BREAK DOWN SHOULD EVENTUALLY OCCUR WITH THE CLOSED LOW
OFFSHORE MIGRATING TOWARD THE COAST TOWARD THE END OF NEXT WEEK. THE
12Z DETERMINISTIC GFS IS A FAST OUTLIER AT THIS POINT SHOWING
PRECIPITATION ARRIVING AT THE COAST DURING THURSDAY, BUT THE VAST
MAJORITY OF ENSEMBLES AND THE HIGHEST PERCENTAGE OF CLUSTERS SHOW
THE WETTER WEATHER PATTERN ARRIVING THU NIGHT INTO FRIDAY. SO, THIS
SHOWS SOME OF THE UNCERTAINTY WITH RESPECT TO THE TIMING. BUT, IT
DOES LOOK LIKE WE'LL HAVE AT LEAST A BRIEF WET PERIOD BY OCT 25 THAT
COULD LAST INTO NEXT WEEKEND. WE'LL CONTINUE TO MAKE ADJUSTMENTS AS
NECESSARY. -SPILDE
MFR WATCHES/WARNINGS/ADVISORIES
OR...FREEZE WARNING UNTIL 9 AM PDT THIS MORNING FOR ORZ024-026.
CA...FREEZE WARNING UNTIL 9 AM PDT THIS MORNING FOR CAZ080>082.
PACIFIC COASTAL WATERS...NONE.
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