Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 251538
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
838 AM PDT SAT OCT 25 2014

.DISCUSSION...AN UPDATE TO THE FORECAST IS NOT NECESSARY THIS
MORNING. STRONG, GUSTY SOUTHERLY WINDS WILL AFFECT THE AREA
THROUGH THIS AFTERNOON, BUT WINDS WILL REMAIN STRONG EAST OF THE
CASCADES THROUGH THE EVENING. PEAK GUSTS SO FAR HAVE REACHED 38
MPH AT THE MEDFORD AIRPORT, 46 MPH AT KINGSLEY FIELD IN KLAMATH
FALLS, 53 MPH AT SUMMER LAKE, 61 MPH AT WEED IN THE SOUTHERN
SHASTA VALLEY, 62 MPH AT THE CAPE BLANCO BUOY, AND 73 MPH AT FLYNN
PRAIRIE IN THE COASTAL RANGE. THE STRONGEST WINDS IN OUR AREA WILL
MAINLY OCCUR BETWEEN 11 AM AND 4 PM.

MODERATE TO HEAVY PRECIPITATION WILL ALSO BE WIDESPREAD DURING THE
NEXT 24 HOURS WITH A SLIGHT CHANCE OF THUNDERSTORMS THROUGH THIS
EVENING. THE SNOW LEVEL WILL BE NEAR 7500 FEET TODAY AND THEN FALL
THIS EVENING TO AROUND 4700 FEET BY SUNDAY MORNING. SNOWFALL
AMOUNTS ARE FORECAST TO BE AROUND 3 TO 6 INCHES IN THE CASCADES
AND UP TO 2 INCHES OVER THE HIGHER TERRAIN OF NORTHERN CALIFORNIA
AND SOUTH CENTRAL OREGON.

A STRONG COLD FRONT IS SWEEPING NORTHEASTWARD, CURRENTLY JUST EAST
OF THE CASCADES AND ON TRACK TO EXIT OUR AREA BY 11 AM. BEHIND
IT, A POTENT SURFACE TROUGH IS ASSOCIATED WITH A DEEP 988MB LOW.
THE LOW IS CENTERED AROUND 125NM WEST OF CAPE BLANCO AND WILL
CONTINUE TO MOVE NORTHEAST TO THE SOUTHERN WASHINGTON COAST BY
THIS EVENING. THE STRENGTH OF THE WINDS TO THIS POINT HAS BEEN
MAINLY RELATED TO THE COLD FRONT, BUT THE PEAK STRENGTH OF THIS
EVENT DURING THE LATE MORNING INTO THE EARLY EVENING WILL BE
RELATED TO THE APPROACH OF THE SURFACE LOW AND TROUGH.

RAIN TODAY WILL BE HEAVIEST IN CURRY COUNTY, JOSEPHINE COUNTY, AND THE
WESTERN AND SOUTHERN PORTION OF SISKIYOU COUNTY. AS MENTIONED IN
THE PREVIOUS DISCUSSION, DOWNSLOPE SOUTHERLY FLOW WILL LIMIT OR
POSSIBLY PREVENT FURTHER RAINFALL IN THE ROGUE AND SHASTA VALLEYS
INTO THIS AFTERNOON, WITH AN EFFECT TO A LESSER EXTENT IN THE
UMPQUA VALLEY. BUT, AS THE SURFACE TROUGH TRACKS INLAND THE WINDS
WILL VEER TO WESTERLY THIS EVENING WITH PEAK PRECIPITATION RATES
OCCURRING IN THE INLAND VALLEYS ACROSS THE CASCADES INTO THE EAST
SIDE. SHOWERS LATE TONIGHT WILL PERSIST INTO SUNDAY WITH THE MOST
FREQUENT ACTIVITY ON WEST FACING SLOPES ON THE WEST SIDE. A BREAK
BETWEEN SYSTEMS IS EXPECTED ON MONDAY BUT THE WEATHER PATTERN
LOOKS TO REMAIN ACTIVE DURING THE NEXT WEEK WITH THE NEXT FRONT
APPROACHING THE COAST BY THE END OF MONDAY EVENING.

&&

.AVIATION...FOR THE 25/12Z TAF CYCLE...A FRONTAL SYSTEM IS MOVING
THROUGH THE REGION RIGHT NOW. STRONG SOUTH WINDS ARE SHIFTING
SUDDENLY TO WEST NORTHWEST AS THE BAND MOVES THROUGH. HOWEVER,
WINDS ALOFT REMAIN STRONG FROM THE SOUTH, AND THIS IS CREATING A
STRONG SPEED AND DIRECTIONAL SHEAR ENVIRONMENT IN THE LOW LEVELS.
WEST SIDE APPROACHES WILL BE VERY TRICKY WITH STRONG LOW LEVEL
SHEAR FOR AT LEAST A COUPLE OF HOURS (THROUGH APPROX 25/14Z). IN
ADDITION, MODERATE RAIN IS OCCURRING WITH THE FRONT. THESE WIND
REVERSALS ARE PROBABLY TEMPORARY AND SOUTH WINDS ARE EXPECTED TO
RESUME THIS MORNING AS STRONG LOW PRESSURE OFFSHORE APPROACHES THE
COAST. SOUTH WINDS ARE EXPECTED TO BE VERY STRONG THIS MORNING AND
AFTERNOON OVER THE COAST, MOUNTAINS, AND EAST SIDE WITH GUSTY
WINDS ALSO SURFACING IN THE WEST SIDE VALLEYS AGAIN. CONSIDERABLE
MOUNTAIN WAVE TURBULENCE IS EXPECTED THIS AFTERNOON NORTH AND EAST
OF ALL MOUNTAINS. -WRIGHT

&&

.MARINE...UPDATED 344 AM PDT SAT 25 OCT 2014...STRONG SURFACE LOW
PRESSURE HAS MOVED INSIDE 130W THIS MORNING AND WILL MOVE NORTH
ALONG THE COAST SKIRTING THE WESTERN EDGE OF OUR WATERS. THIS PUTS
THE STRONGEST PRESSURE GRADIENTS OVER OUR WATERS THIS MORNING INTO
EARLY AFTERNOON, AND AS A RESULT, SOUTH WINDS WILL CONTINUE TO
INCREASE. WINDS PEAK JUST AS THE LOW MOVES TO OUR NORTH LATE THIS
MORNING, WITH HIGH END GALES AND STORM FORCE GUSTS OVER MUCH OF
THE AREA. SEAS WILL ALSO BE VERY STEEP AND CHAOTIC TODAY. WINDS
SHIFT TO THE WEST AND BEGIN TO DIMINISH LATER THIS AFTERNOON, BUT
SEAS WILL CONTINUE INTO THE EVENING BEFORE SUBSIDING. WE`LL SEE A
RELATIVE BREAK IN THE STORMINESS SUNDAY AND MONDAY, BUT ANOTHER
FRONT WILL BRING STRONG SOUTH WINDS AND VERY STEEP SEAS TUESDAY.
MORE FRONTS ARE EXPECTED THROUGH THE WEEK AS THIS ACTIVE PATTERN
CONTINUES OVER THE NORTHEAST PACIFIC. -WRIGHT


&&

.PREV DISCUSSION... /ISSUED 321 AM PDT SAT OCT 25 2014/

DISCUSSION...LOW PRESSURE IS NOW MOVING INSIDE OF 130 W. NEAR THE
CENTER OF THE LOW THERE HAVE BEEN A FEW LIGHTNING STRIKES WHICH
SUGGEST THERE IS PLENTY OF ENERGY WITH THIS. THE MODELS ARE IN GOOD
AGREEMENT TRACKING THE LOW NORTHEAST JUST WEST OF THE OREGON COAST
TODAY, THEN MOVING INLAND NEAR GRAYS HARBOR WASHINGTON THIS EVENING.
THIS TRACK IS GOING TO BE FAVORABLE FOR MODERATE TO STRONG WINDS FOR
MOST OF THE FORECAST AREA. WINDS HAVE BEEN ON THE INCREASE DURING
THE OVERNIGHT HOURS OVER MOST OF THE FORECAST AREA. THIS PAST HOUR
WEED HAD SUSTAINED WIND AT 36 MPH WITH GUST TO 52 MPH. IT`S BLOWING
PRETTY GOOD AT ASHLAND AND IT HAS PICKED UP HERE RECENTLY AT THE
AIRPORT. EXPECT WINDS TO PICK UP IN THE ROGUE VALLEY DURING THE MORNING
AND CONTINUE INTO THIS AFTERNOON. THE STRONGEST WINDS WILL BE EAST
OF THE CASCADES NEAR SUMMER LAKE...SHASTA VALLEY...MOUNTAINS AND
THE SOUTHERN END OF THE ROGUE VALLEY. IN FACT MODELS ARE
SUGGESTING WINDS COULD REACH WARNING CRITERIA THERE AND HAVE
ISSUED A HIGH WIND WARNING. ALSO SOUTH WINDS COULD MIX DOWN INTO
THE UMPQUA BASIN AND HAVE EXPANDED THE WIND ADVISORY TO INCLUDE
MUCH OF DOUGLAS COUNTY. DETAILS ON THESE CAN BE FOUND AT NPWMFR.

IN ADDITION, TO WIND IMPACTS, THIS STRONG LOW WILL BRING RAIN TO THE
COAST EARLY THIS MORNING. IN FACT IT`S ALREADY PUSHING INTO THE
SOUTH COAST. PRECIPITATION WILL MOVE INLAND TODAY, BUT DOWNSLOPE
IN THE ROGUE VALLEY, IS LIKELY TO PREVENT ANYTHING MEASURABLE
FROM AROUND SUNRISE UNTIL LATE THIS AFTERNOON. COLD AIR ALOFT
WILL PUSH IN IMMEDIATELY BEHIND THE FRONT AND ASSOCIATED
INSTABILITY WILL BRING A CHANCE FOR THUNDERSTORMS WITH THE BEST
CHANCE AT THE COAST THIS MORNING, THEN INLAND LATE THIS MORNING
THROUGH THE AFTERNOON. OF NOTE IS THAT ANY THUNDERSTORMS THAT
OCCUR MAY BRING STRONG GUSTY WINDS DUE TO THE STRONG WINDS ALOFT.
PRECIPITATION AMOUNTS WILL BE HIGHEST ALONG THE COAST AND COASTAL
MOUNTAINS WITH 2-4 INCHES POSSIBLE AND UP TO 2 INCHES ELSEWHERE IN
CURRY, COOS, JOSEPHINE AND WESTERN SISKIYOU COUNTY. UP TO AN INCH
IS POSSIBLE ALONG THE CASCADES AND 0.25 TO 0.50 OF AN INCH
ELSEWHERE WEST OF THE CASCADES WITH MOST OF THAT COMING IN
TONIGHT. EAST SIDE AMOUNTS WILL BE MAINLY AROUND 0.25 IN.

POST FRONTAL SOWERS WILL CONTINUE TONIGHT INTO SUNDAY WITH MOST
SHOWERS EXPECTED TO BE ALONG AND WEST OF THE CASCADES. SNOW LEVELS
WILL DROP TO AROUND 5000 FEET WITH 3-6 INCHES POSSIBLE OVER THE
HIGHER ELEVATIONS ALONG THE CASCADES BY SUNDAY MORNING. WINDS WILL
ALSO DECREASE TONIGHT EAST OF THE CASCADES AND ARE NOT EXPECTED TO
BE A CONCERN ON SUNDAY.

POST FRONTAL SHOWERS IN A MOIST NORTHWEST FLOW CONTINUE SUNDAY
MORNING. 500 MB HEIGHTS INCREASE IN THE AFTERNOON WHICH SHOULD
RESULT IN DECREASING SHOWERS FROM SOUTH TO NORTH. A BREAK IN THE
WEATHER IS STILL EXPECTED MONDAY WITH DRY CONDITIONS AND MILDER
TEMPERATURES.  ANOTHER FRONT WILL IMPACT THE AREA MONDAY NIGHT INTO
TUESDAY BRINGING ANOTHER ROUND OF MODERATE TO HEAVY PRECIPITATION TO
THE COAST AND COASTAL MOUNTAINS. THE GFS AND ECMWF SUGGEST THE FRONT
COULD STALL TUESDAY NIGHT THROUGH WEDNESDAY BEFORE LIFTING NORTH AS
A WARM FRONT WEDNESDAY NIGHT. -PETRUCELLI

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH WIND WARNING UNTIL 11 PM PDT THIS EVENING FOR ORZ029>031.
     HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON FOR ORZ021-022.
     WIND ADVISORY UNTIL 5 PM PDT THIS AFTERNOON FOR ORZ023.
     HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON FOR ORZ028.
     HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON FOR ORZ026.

CA...HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON FOR CAZ080.
     HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON FOR CAZ082.
     HIGH WIND WARNING UNTIL 5 PM PDT THIS AFTERNOON FOR CAZ081.
     HIGH WIND WARNING UNTIL 11 PM PDT THIS EVENING FOR CAZ083-085.

PACIFIC COASTAL WATERS...GALE WARNING UNTIL 2 PM PDT THIS AFTERNOON FOR
     PZZ350-356-370-376.
     HAZARDOUS SEAS WARNING UNTIL 8 PM PDT THIS EVENING FOR
     PZZ350-356-370-376.

$$

DW/SBN






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