769
FXUS66 KMFR 202254
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
254 PM PST MON JAN 20 2025
DISCUSSION
CLEAR SKIES HAVE DEVELOPED THIS AFTERNOON AS TEMPERATURES HAVE
SHOT THROUGH THE 30'S AND ARE CURRENTLY IN THE UPPER 40'S IN MOST
OF THE VALLEYS WEST OF THE CASCADES. CLOSER TO THE COAST, HIGHS
ARE IN THE UPPER 50'S WITH SOME LIGHT NORTH EAST TO EAST FLOW AT
4500 FEET. SOME HIGHER CLOUDS ARE STARTING TO SHUFFLE INTO THE
FORECAST AREA, AND THEY SHOULD BECOME MORE WIDESPREAD LATER
TONIGHT BASED ON CLOUD COVER FROM THE HREF MODEL.
BY LATER TONIGHT, WE'LL LIKELY SEE MORE VALLEY STRATUS AND
FREEZING FOG IN THE VALLEYS. THE MET AND MAV GUIDANCE IS
PREDICTING FOG, AND LOW TEMPERATURES WILL BE WELL BELOW FREEZING
IN MANY OF THE VALLEYS TONIGHT. THE HIGH CLOUDS COULD THROW A
WRENCH IN THINGS, ALTHOUGH WE'RE THINKING THAT THE DRY LAYER AND
INVERSION STRENGTH SHOULD USHER IN PLENTY OF FOG.
BY TUESDAY, MID AND LOW LEVEL FLOW BECOMES ONSHORE WITH LIGHT
WESTERLY WINDS. NO BIG PATTERN CHANGES AS HIGH PRESSURE REMAINS IN
CONTROL, ALTHOUGH THE DIFFERENT WIND DIRECTION COULD PUSH SOME
LOWER STRATUS INTO THE COAST TUESDAY AFTERNOON AND EVENING.
HIGH PRESSURE WILL STRENGTHEN INTO WEDNESDAY WITH THE 500 MB
RIDGE CENTERED RIGHT OVER SOUTHERN OREGON AND NORTHERN
CALIFORNIA. THE END RESULT SHOULD BE PLENTY OF FREEZING FOG, SOME
OF IT BEING VERY THICK AND UNDER 1/4 A MILE GIVEN THE STRENGTH OF
SURFACE HIGH.
FINALLY, THE WEATHER WILL CHANGE AROUND THURSDAY WHEN THE MAJORITY
OF MODELS ARE PREDICTING AN UPPER LEVEL TROUGH AND COLD FRONT TO
PUSH THROUGH THE FORECAST AREA. THE END RESULT WILL BE A 30 TO 40%
CHANCE OF PRECIPITATION ACROSS THE MAJORITY OF THE FORECAST AREA
WITH DRIER PROBABILITIES DOWN TO 0 TO 20 PERCENT FARTHER SOUTH.
PRECIPITATION WILL LIKELY BE LIGHT AS NONE OF THE ENSEMBLE MEMBERS
ARE PREDICTING MORE THAN 0.3 INCHES THROUGH THIS FRIDAY EVENT.
HIGH PRESSURE WILL SETTLE BACK IN THIS WEEKEND.
-SMITH
AVIATION...20/18Z TAFS
FREEZING FOG IS BRINGING LIFR LEVELS TO
MEDFORD. THE MORNING SOUNDING SHOWS A VERY DRY AIR MASS
APPROXIMATELY 1200 FEET AGL. GUIDANCE SHOWS THE FOG AND LOW CLOUDS
BURNING OFF TOWARDS 21Z. GIVEN THE SHALLOW MOIST LAYER, IT'S
POSSIBLE MEDFORD COULD BREAK OUT EARLY THIS AFTERNOON AND HAVE
INTRODUCED THIS IN THE TAF. HOWEVER, WE'LL KEEP A WATCH ON THE TREND
OF THE SATELLITE IMAGE AND ADJUSTMENTS WILLBE MADE AS NEEDED. IT'S
ALSO WORTH NOTING IMPROVING CONDITIONS COULD BE DELAYED BY AN HOUR
OR TWO.
SATELLITE IMAGE SHOWS LOW CLOUDS AND FOG BURNING OFF IN THE UMPQUA
BASIN AND ROSEBURG COULD CLEAR OUT TOWARDS 18Z AND HAVE THIS AS THE
PREVAILING CONDITION IN THE TAF.
LOW CLOUDS AND FOG WILL RETURN IN THE SAME AREAS AS THIS MORNING
EARLY THIS EVENING AND LASTING UNTIL THE END OF THE TAF PERIOD.
ELSEWHERE, VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD.
-PETRUCELLI
MARINE...UPDATED 200 PM MONDAY, JANUARY 20, 2025
WINDS WILL
DIMINISH THIS AFTERNOON AS THE THERMAL TROUGH ALONG THE SOUTH OREGON
COAST WEAKENS. RELATIVELY CALM CONDITIONS ARE LIKELY THIS EVENING
INTO TUESDAY WITH WEST-NORTHWEST SWELL DOMINATED SEAS REACHING A
MINIMUM AT AROUND 5 TO 6 FT AT 14 SECONDS.
THE THERMAL TROUGH IS EXPECTED TO STRENGTHEN AGAIN WEDNESDAY WITH
SEAS LIKELY BECOMING STEEP, AT LEAST FOR THE OUTER WATERS SOUTH OF
CAPE BLANCO. THERE'S GOOD AGREEMENT FOR MODERATE TO STRONG NORTH
WINDS LATER IN THE WEEK WITH A STRONG THERMAL TROUGH DEVELOPING
ALONG THE COAST. WINDS ARE LIKELY TO REACH LOW END GALES WITH STEEP
TO VERY STEEP SEAS. -PETRUCELLI
MFR WATCHES/WARNINGS/ADVISORIES
OR...AIR STAGNATION ADVISORY UNTIL 10 AM PST TUESDAY FOR ORZ021-
023>026-029>031.
BEACH HAZARDS STATEMENT UNTIL 4 PM PST THIS AFTERNOON FOR ORZ021-
022.
CA...NONE.
PACIFIC COASTAL WATERS...BEACH HAZARDS STATEMENT UNTIL 4 PM PST THIS
AFTERNOON FOR PZZ350-356.
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