924
FXUS66 KMFR 182252
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
252 PM PST TUE FEB 18 2025
DISCUSSION
RADAR IS SHOWING LIGHT RETURNS WITH OVER RUNNING
PRECIPITATION ALONG AND AHEAD OF A WARM FRONT. THIS WILL CONTINUE
INTO THIS AFTERNOON. HOWEVER, PRECIP AMOUNTS WILL BE VERY LIGHT AND
INTERMITTENT.
SATELLITE IMAGE SHOWS AN UPPER TROUGH DIGGING OUT NEAR 140W AND
MOVING EAST TOWARDS THE FORECAST AREA. ALL INDICATIONS ARE THE UPPER
TROUGH WILL BECOME NEGATIVELY TILTED LATE TONIGHT INTO WEDNESDAY
MORNING AS IT REACHES THE COAST, WHICH IS INDICATIVE OF STRENGTHENING
OR DEEPENING LOW. THERE IS A GENERAL CONSENSUS SHOWING A SURFACE LOW
DEVELOPING INSIDE OF 130W ALONG WITH AN INCREASING PRESSURE
GRADIENT. THERE ARE A COUPLE OF OUTLIERS, BUT THIS MAY BE SUSPECT
GIVEN THE UPPER TROUGH WILL BECOME NEGATIVELY TILTED. IN ADDITION,
THE GFS SHOWS PRESSURE GRADIENTS BETWEEN ARCATA AND NORTH BEND
PEAKING OUT AT 12.2 MB AROUND 7 AM PST, BUT STILL GREATER THAN 8.0
MB BETWEEN 4 AM AND 7 AM PST. THE NAM IS WEAKER AND PEAKS OUT AT 7.1
MB EARLY WEDNESDAY MORNING. GIVEN THE ABOVE, HAVE ISSUED A HIGH WIND
WARNING FOR THE HEADLANDS AND EXPOSED AREAS ALONG HIGHWAY 101 FOR
THE SOUTH OREGON COAST FROM CAPE BLANCO SOUTH.
THE PATTERN IS ALSO ONE THAT IS FAVORABLE FOR MODERATE TO STRONG
WINDS IN THE SHASTA VALLEY NEAR WEED AND THE ROGUE VALLEY WITH
INCREASING SOUTHEAST WINDS LATER TONIGHT INTO WEDNESDAY MORNING.
WINDS WILL BE STRONGEST NEAR WEED AND SOUTH OF MEDFORD TO ASHLAND
DURING THIS TIME, AND A WIND ADVISORY HAS BEEN ISSUED. PLEASE
SEE NPWMFR FOR MORE DETAILS.
THE DURATION OF WINDS FOR THE COAST, SHASTA VALLEY AND ROGUE VALLEY
SHOULD BE OF SHORTER DURATION, BUT THE IMPACTS ARE THERE, THUS IT IS
PRUDENT THE WARNINGS AND ADVISORIES WERE ISSUED.
A COLD FRONT AND UPPER TROUGH WILL REACH THE COAST LATE TONIGHT,
THEN MOVING INLAND 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 FROM LATE WEDNESDAY MORNING AND
AFTERNOON. GENERALLY THEY ARE EXPECTED TO BE BETWEEN 4000-4500 FEET.
PRECIPITATION WEDNESDAY WILL BE MAINLY CONCENTRATED ALONG THE
CASCADES AND COASTAL MOUNTAINS IN SOUTHWEST OREGON. ALONG THE
CASCADES, SNOWFALL RATES OF AN INCH PER HOUR ARE LIKELY FOR ABOUT A
6 HOUR PERIOD FROM LATE WEDNESDAY MORNING THROUGH WEDNESDAY
AFTERNOON ALONG WITH VISIBILITY LOWERING TOWARDS A 1/4 MILE DURING
TIMES OF HEAVY SNOW. THIS WAS THE DRIVING FORCE FOR ISSUING A
WINTER STORM WARNING. PLEASE SEE WSWMFR FOR MORE DETAILS.
SHOWERS WILL CONTINUE WEDNESDAY EVENING, THEN DIMINISHING WEDNESDAY
NIGHT AS THE UPPER TROUGH SHIFTS SOUTH.
UPPER RIDGING WILL BUILDS INTO THE AREA THURSDAY RESULTING IN DRY
AND MILDER WEATHER WITH THE STORM TRACK SHIFTING NORTH.
THE UPPER RIDGE WILL FLATTEN OUT SOME FRIDAY, WITH SOME
PRECIPITATION SLIPPING THROUGH ALONG THE COAST, OFFSHORE AND
NORTHWEST DOUGLAS AND COOS COUNTY IN THE AFTERNOON. THIS LINES UP
WITH THE MAJORITY OF THE INDIVIDUAL ENSEMBLE MEMBERS SOLUTIONS.
THE STORM TRACK WILL SHIFT SOUTH SATURDAY AFTERNOON WITH
PRECIPITATION INCREASING ALONG THE COAST AND NORTHWEST DOUGLAS
COUNTY, THEN SHIFTING SOUTH AND EAST OVER A GOOD PORTION OF THE
AREA SATURDAY NIGHT. THERE HAS BEEN SOME QUESTION AS TO WHERE THE
HEAVIEST PRECIPITATION WILL BE, BUT IT'S A GOOD BET THE HIGHEST
PRECIP AMOUNTS WILL BE ALONG THE NORTH COAST. THIS CAN VARY
DEPENDING ON HOW THE FRONTAL BOUNDARY MOVES SATURDAY AFTERNOON AND
SATURDAY NIGHT. HOWEVER, THE MAJORITY OF THE INDIVIDUAL ENSEMBLE
MEMBERS AND OPERATIONAL MODELS SUGGEST IT WILL BE IN THE ABOVE
MENTIONED AREAS. SNOW LEVELS DURING THIS TIME WILL BE HIGH WITH
ANY ROAD SNOW CONCERNS CONFINED TO AROUND CRATER LAKE. EVEN THEN
IT'S NOT EXPECTED TO BE MUCH.
THE FRONTAL BOUNDARY IS EXPECTED TO REMAIN NEARLY STATIONARY
SUNDAY INTO SUNDAY NIGHT, THEN LIFTING NORTH BRIEFLY BEFORE
RETURNING MONDAY AFTERNOON AS AN UPPER TROUGH AND FRONT
APPROACHES. UPPER RIDGING RETURNS TUESDAY WITH DRY WEATHER
EXPECTED. -PETRUCELLI
AVIATION...18/18Z TAFS
WITH THE EXCEPTION OF SOME LINGERING MVFR
VISIBILITIES AT KLAMATH FALLS, VFR LEVELS UNDER HIGH CEILINGS ARE
PRESENT ACROSS NORTHERN CALIFORNIA AND SOUTHERN OREGON. A WARM FRONT
MOVING OVER THE AREA IS BRINGING SOME SHOWERS WEST OF THE CASCADES
THAT MAY LOCALLY LOWER VISIBILITIES, BUT SUBSTANTIAL ACTIVITY IS NOT
EXPECTED THROUGH THIS AFTERNOON.
AN IMPACTFUL SYSTEM WILL APPROACH THE OREGON COAST THIS EVENING,
BRINGING WIDESPREAD SHOWERS AND GUSTY SOUTHERLY WINDS INTO
WEDNESDAY. MORE PRECIPITATION IS EXPECTED, ESPECIALLY ALONG THE
COAST AND OVER THE CASCADES. SNOW LEVELS OF 5000 FEET OR HIGHER WILL
LIMIT SNOWFALL TO THE HIGHEST AREAS, WITH HEAVY SNOWFALL EXPECTED
OVER THE CASCADES NEAR THE END OF THE TAF PERIOD. LOW LEVEL WIND
SHEAR OVER HIGHER TERRAIN MAY ALSO BE PRESENT AS THE SYSTEM MOVES
OVER LAND. WHILE GUIDANCE DOES NOT SHOW THIS SHEAR DIRECTLY OVER
MEDFORD, SHEAR OVER THE SURROUNDING MOUNTAINS FOLLOWS THE SAME
TIMING AS ROSEBURG. SHEAR ACROSS THE AREA LOOKS TO DISPERSE BY THE
END OF THE TAF PERIOD. -TAD
MARINE...UPDATED 230 PM PST TUESDAY, FEBRUARY 18, 2025
STEEP SEAS
CONTINUE THIS AFTERNOON IN ALL WATERS AHEAD OF AN APPROACHING LOW
PRESSURE SYSTEM. THIS SYSTEM WILL BRING WIDESPREAD MARINE RAINFALL,
CONDITIONS WILL RAPIDLY DETERIORATE AS THE SYSTEM APPROACHES. GUSTY
SOUTHERLY WINDS ARE FORECAST TO REACH GALE STRENGTH LATE TONIGHT
THROUGH WEDNESDAY MORNING. WIND GUSTS MAY LOCALLY REACH OVER 50 KTS
IN ALL WATERS. THE HIGHEST CHANCES FOR THESE 50 KT WINDS WILL BE ON
WEDNESDAY MORNING, FROM PORT ORFORD AND NORTHWARD AND WITHIN 30 NM
FROM THE COAST.
THE SYSTEM IS FORECAST TO MOVE AWAY TO THE NORTH LATE WEDNESDAY
MORNING, BUT VERY STEEP AND HAZARDOUS SEAS COULD CONTINUE IN ALL
WATERS THROUGH THURSDAY MORNING. WHILE A BRIEF PERIOD OF BELOW
ADVISORY LEVEL SEAS IS POSSIBLE LATE THURSDAY, ANOTHER FRONT
ARRIVING ON FRIDAY WILL LIKELY REBUILD STEEP SEAS GOING INTO THE
WEEKEND. -TAD
MFR WATCHES/WARNINGS/ADVISORIES
OR...WIND ADVISORY FROM 1 AM TO 7 AM PST WEDNESDAY FOR ORZ026.
HIGH WIND WARNING FROM 1 AM TO 7 AM PST WEDNESDAY FOR ORZ021-
022.
COASTAL FLOOD ADVISORY FROM 4 AM TO 4 PM PST WEDNESDAY FOR
ORZ021-022.
WINTER STORM WARNING FROM 7 AM WEDNESDAY TO 4 PM PST THURSDAY
FOR ORZ027-028.
CA...WIND ADVISORY FROM 1 AM TO 7 AM PST WEDNESDAY FOR CAZ081.
PACIFIC COASTAL WATERS...COASTAL FLOOD ADVISORY FROM 4 AM TO 4 PM PST
WEDNESDAY FOR PZZ350-356.
SMALL CRAFT ADVISORY UNTIL 10 PM PST THIS EVENING FOR PZZ350-356-
370-376.
GALE WARNING FROM 10 PM THIS EVENING TO 10 AM PST WEDNESDAY FOR
PZZ350-356-370-376.
HAZARDOUS SEAS WARNING FROM 10 AM WEDNESDAY TO 4 AM PST THURSDAY
FOR PZZ350-356-370-376.
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