139
FXUS66 KMFR 170420
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
820 PM PST SUN FEB 16 2025
..UPDATED AVIATION AND MARINE DISCUSSIONS
AVIATION...17/06Z TAFS
MOIST ONSHORE FLOW WILL CONTINUE TO
PRODUCE SHOWERS THROUGHOUT THE AREA OVER THE NEXT 24 HOURS. EXPECT
MAINLY VFR CONDITIONS, ALTHOUGH MVFR CEILINGS AND VISIBILITIES WILL
ACCOMPANY AREAS OF SHOWERS, ESPECIALLY SNOW SHOWERS ABOVE ROUGHLY
4500 FEET MSL. MVFR CONDITIONS WILL BECOME MORE WIDESPREAD THROUGH
THE DAY MONDAY ALONG AND WEST OF THE CASCADES, WHILE SHOWERS
GENERALLY DIMINISH, BUT NOT END, TO THE EAST. -BPN
MARINE...UPDATED 800 PM PST SUNDAY, FEBRUARY 16, 2025
AS WIND
DRIVEN WAVES DIMINISH, LONG PERIOD WESTERLY SWELL IS FORECAST TO
BUILD IN AREA WATERS THIS EVENING. AS A RESULT, SEAS WILL TRANSITION
TO SWELL DOMINATED, AND REMAIN STEEP THROUGH MONDAY.
AFTER A BRIEF PERIOD OF BELOW ADVISORY SEAS LATE MONDAY NIGHT INTO
TUESDAY MORNING, THE NEXT FRONT WILL BRING MORE MARINE SHOWERS AND
ANOTHER ROUND OF GUSTY SOUTHERLY WINDS. EXPECTED WIND SPEEDS HAVE
BEEN INCREASING WITH ADDITIONAL GUIDANCE, AND NOW GALE FORCE GUSTS
AND VERY STEEP SEAS ARE LIKELY TO ACCOMPANY THE FRONT. A GALE WATCH
IS IN PLACE FOR ALL WATERS FOR TUESDAY AFTERNOON INTO EARLY
WEDNESDAY MORNING.
AFTER A BRIEF BREAK LATE IN THE WEEK, ANOTHER FRONT IS DUE TO PASS
THROUGH THE AREA THIS WEEKEND. -BPN
PREV DISCUSSION... /ISSUED 212 PM PST SUN FEB 16 2025/
DISCUSSION...MOIST ONSHORE FLOW WITH FAVORABLE OROGRAPHICS FOR THE
CASCADES WILL CONTINUE THROUGH MONDAY AFTERNOON. SHOWERS WILL BE
MAINLY CONCENTRATED ALONG THE CASCADES AND COASTAL MOUNTAINS IN
SOUTHWEST OREGON.
SNOW WILL BE PERSISTENT IN THE CASCADES IS EXPECTED TONIGHT WITH A
MOIST WESTERLY FLOW PROVIDING GOOD OROGRAPHICS ALONG THE CASCADES
THROUGH AT LEAST MONDAY AFTERNOON. GUIDANCE SUGGEST SNOWFALL RATES
INCREASE LATE THIS AFTERNOON THROUGH TONIGHT AND IT'S LIKELY (80-
100%) CHANCE FOR SNOWFALL RATES OF AN INCH PER HOUR DURING THIS
TIME. THIS WILL BE THE MAIN DRIVING FORCE FOR THE WINTER STORM
WARNING. UNDER DIFFERENT CIRCUMSTANCES, STORM TOTAL SNOW IS OVER A
LONG DURATION AND THIS IN ITSELF WOULD NOT BE ENOUGH TO WARRANT A
WINTER STORM WARNING, BUT SNOWFALL RATES WILL.
MOIST ONSHORE FLOW WITH AN UPPER TROUGH OVER THE AREA MONDAY WILL
KEEP THE SHOWERS GOING, WITH MOST CONCENTRATED IN THE OROGRAPHIC
FAVORED UPSLOPE AREAS ALONG THE CASCADES, AND THE COASTAL MOUNTAINS,
IN SOUTHWEST OREGON.
SNOWFALL ACCUMULATIONS FOR THE CASCADES COULD BE MITIGATED DURING THE
DAY MONDAY DUE TO DAYTIME HEATING SHOULD PUT A CAP ON THE AMOUNT OF
SNOW IN THE AFTERNOON.
SHOWERS WILL CONTINUE INTO MONDAY NIGHT, BUT THEY WILL BE GRADUALLY
DIMINISHING AND MOST WILL BE CONCENTRATED ALONG THE CASCADES.
UPPER RIDGING BUILDS INTO THE AREA BRIEFLY TUESDAY MORNING WHICH
SHOULD GIVE US A BREAK IN PRECIPITATION. THIS WON'T LAST LONG WITH
WARM FRONTAL PRECIPITATION MOVING INTO THE AREA (CASCADES WEST)
TUESDAY AFTERNOON. SNOW LEVELS TUESDAY AFTERNOON WILL BE ON THE RISE
TO AROUND 5500 FEET TUESDAY AFTERNOON AND NEAR 6000 FEET TUESDAY
EVENING.
A COLD FRONT AND UPPER TROUGH WILL MOVE IN EARLY WEDNESDAY MORNING
WITH SNOW LEVELS FALLING IN THE MORNING, THEN REBOUNDING SOME IN THE
AFTERNOON DUE TO DIURNAL EFFECTS. SNOW LEVELS WILL VARY DEPENDING ON
PRECIP INTENSITY SINCE WE'LL BE IN A CONVECTIVE ENVIRONMENT, BUT
WILL GENERALLY BE BETWEEN 4000-4500 FEET. WEDNESDAY WILL BE SIMILAR
TO TODAY WITH VALLEY RAIN AND MOUNTAINS SNOW SHOWERS.
SHOWERS WILL CONTINUE WEDNESDAY EVENING, THEN DIMINISHING WEDNESDAY
NIGHT AS THE UPPER TROUGH SHIFTS SOUTH.
UPPER RIDGING WILL BUILDS INTO THE AREA THURSDAY AND FRIDAY
RESULTING IN DRY AND MILDER WEATHER WITH THE STORM TRACK SHIFTING
NORTH. THIS IS BEING SUPPORTED BY THE CLUSTERS, AND THE MAJORITY OF
THE INDIVIDUAL ENSEMBLE MEMBERS. IN CONTRAST THE NBM IS ONE AGAIN
TOO HIGH AND TOO FAR SOUTH, ESPECIALLY ON FRIDAY.
THERE ARE SIGNS THE STORM TRACK COULD SHIFT SOUTH SATURDAY AND BRING
A CHANCE OF PRECIPITATION IN THE NORTHWEST PART OF THE FORECAST AREA
SATURDAY AFTERNOON, THEN ALONG THE COAST AND NORTH OF THE UMPQUA
DIVIDE SATURDAY NIGHT AND SUNDAY. HOWEVER ABOUT 50% OF THE
INDIVIDUAL ENSEMBLE MEMBERS KEEP THE STORM TRACK FAR ENOUGH NORTH TO
KEEP IT DRY IN OUR AREA ON SATURDAY. THE CLUSTERS ARE ALSO IN
AGREEMENT SHOWING UPPER RIDGING BUILDING IN FOR THE LATTER PART OF
NEXT WEEK INTO NEXT WEEKEND. THE POSITION OF THE UPPER RIDGE SUGGEST
THE STORM TRACK SHOULD REMAIN JUST NORTH OF OUR AREA. HOWEVER IT'S
STILL CLOSE ENOUGH TO AT LEAST WARRANT A CHANCE OF PRECIPITATION
ALONG THE COAST AND NORTH OF THE UMPQUA DIVIDE NEXT SUNDAY. T
-PETRUCELLI
MFR WATCHES/WARNINGS/ADVISORIES
OR...WINTER STORM WARNING UNTIL 4 PM PST MONDAY FOR ORZ027-028.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY UNTIL 4 AM PST TUESDAY
FOR PZZ350-356-370-376.
GALE WATCH FROM TUESDAY AFTERNOON THROUGH LATE TUESDAY NIGHT FOR
PZZ350-356-370-376.
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