000
FXUS66 KMFR 190343
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
843 PM PDT SAT MAY 18 2013

.DISCUSSION...A COLD FRONT MOVED THROUGH THE AREA EARLIER TODAY
PRODUCING SCATTERED SHOWERS. A FEW LIGHTNING STRIKES WERE ALSO
OBSERVED OVER PORTIONS OF MODOC COUNTY AND EASTERN LAKE COUNTY.
BEAR FLAT RAWS IN MODOC COUNTY WAS ABLE TO MUSTER 0.27 OF AN INCH
OF RAINFALL BENEATH A DOWNPOUR THIS AFTERNOON. BUT, MOST AREAS
ENDED UP WITH ONLY A FEW HUNDREDTHS. THE FRONT IS EXITING EAST OF
THE AREA THIS EVENING WITH ONSHORE FLOW SETTING UP BEHIND IT. THIS
WILL KEEP CLOUDS AND ISOLATED TO SCATTERED SHOWERS ALONG THE
CASCADES AND FROM THE UMPQUA VALLEY TO THE NORTH COAST OVERNIGHT.
THE REMAINDER OF THE AREA WILL BE PARTLY CLOUDY WITH ANY ISOLATED
SHOWERS THIS EVENING DRYING UP. HAVE MASSAGED THE SKY/POP GRIDS A
BIT TO ACCOUNT FOR EVENING SATELLITE/RADAR TRENDS.

AN UPPER LEVEL RIDGE WILL TAKE HOLD OVER THE AREA SUNDAY INTO
MONDAY RESULTING IN DEVELOPING OFFSHORE FLOW AND A WARMING TREND
AREA WIDE. EXPECT SUNDAY`S HIGHS TO BE 6-10 DEGREES HIGHER THAN
TODAY AND THEN MONDAY`S HIGHS UP ANOTHER 6-10 DEGREES. THAT WOULD
RESULT IN HIGHS IN THE MID 70S IN THE ROGUE VALLEY ON SUNDAY THEN
THE MID 80S ON MONDAY.

HOWEVER, THE WARM UP WILL BE SHORT-LIVED AS A SHARP UPPER TROUGH
DIVES SOUTHEASTWARD INTO THE PACIFIC NORTHWEST TUESDAY. GUSTY
WINDS WILL PRECEDE THE COLD FRONT, ESPECIALLY EAST OF THE CASCADES
TUESDAY. THE FRONT WILL BE ACCOMPANIED BY SOME RAIN, BUT PERHAPS
THE MORE NOTICEABLE FEATURE WILL BE THE DRAMATIC TEMPERATURE DROP.
EXPECTED HIGHS WEDNESDAY AND THURSDAY WILL BE NO BETTER THAN THE
UPPER 50S/LOW 60S. SEE PREVIOUS AFD FOR MORE DETAILS REGARDING
THE SHARP CHANGE EXPECTED AT MIDWEEK. SPILDE

&&

.AVIATION...BASED ON THE 19/00Z TAF CYCLE.

AREAS OF MVFR CIGS WITH ISOLATED IFR CIGS FROM THE CASCADES WEST
WITH HIGHER TERRAIN OBSCURED WILL CLEAR TO VFR BY SUNDAY AFTERNOON
AND REMAIN VFR THROUGH SUNDAY NIGHT.  ELSEWHERE...VFR CONDITIONS
WILL PREVAIL THROUGH SUNDAY NIGHT. STOCKTON

&&

.PREV DISCUSSION... /ISSUED 509 PM PDT SAT MAY 18 2013/

DISCUSSION...THE REGION IS IN FOR A TEMPERATURE ROLLER COASTER
RIDE AS AN ACTIVE PATTERN REMAINS OVER THE WEST COAST THROUGH THE
NEXT WEEK. THE COLD FRONT IS MOVING THROUGH THE REGION TODAY WITH
SHOWERS CONTINUING BEHIND IT AS LAPSE RATES REMAIN MODERATE AND
FLOW BECOMES ONSHORE. AS SURFACE COOLING SLOWLY PROGRESSES UNDER
THE SC DECK IN NW PORTIONS OF THE AREA, SHOWERS LINGER THE LONGEST
THERE THROUGH THE EVENING AND OVERNIGHT. UPPER LEVEL RIDGE BUILDS
OVER THE REGION BY LATE TONIGHT WITH OFFSHORE FLOW DEVELOPING OVER
THE SOUTHERN COASTAL RANGE BY SUNDAY MORNING. WITH CLEARING
EXPECTED SUNDAY IN THE EXPANDING OFFSHORE FLOW, WE`LL SEE A WARM
UP OF AROUND TEN DEGREES COMPARED TO TODAY. OFFSHORE FLOW REMAINS
OVERNIGHT SUNDAY WITH HIGHER TEMPS ON THE RIDGES STARTING THE
REGION OFF TO ANOTHER GOOD WARM UP MONDAY WITH TEMPS WARMING
AROUND ANOTHER TEN DEGREES. AN UPPER LEVEL LOW MOVES INTO THE
REGION FROM THE NORTHWEST MONDAY NIGHT WITH A COLD FRONT MOVING
THROUGH TUESDAY. MODEL 850 MB TEMPS ARE IN THE LOWER TEENS TUESDAY
MORNING...DROPPING TO AROUND 0 C RIGHT BEHIND THE FRONT. HIGH
TEMPERATURES OVER MUCH OF THE WEST SIDE MIGHT BE IN THE MORNING
WITH TEMPS DROPPING THROUGH THE LATER AFTERNOON AS THE FRONT MOVES
IN COMBINING WITH SHOWERS. BY WEDNESDAY MORNING THE EC AND GFS
HAVE COME IN MUCH BETTER AGREEMENT WITH THE COLD AIR MASS...BOTH
SHOWING 850 TEMPS IN THE -3 TO -4 C RANGE...BRINGING A LATE SEASON
DUSTING OF SNOW POSSIBLY AS LOW AS 3000 FEET. WITH THE VERY WARM
TEMPERATURES AND SUN FOR THE PRECEDING DAYS THIS SNOW SHOULD MELT
VERY QUICKLY EXCEPT FOR LOCATIONS WHERE THERE IS STILL SNOW ON THE
GROUND. HAVE MORE BROAD-BRUSHED THE REMAINDER OF THE EXTENDED AS
BOTH THE GFS AND THE EC WOBBLE A CUTOFF LOW OVER THE PAC NW
THROUGH THE REMAINDER OF THE WEEK. THE GFS HAS REMAINED THE MOST
CONSISTENT WITH YESTERDAYS MUCH MORE SOUTHERLY POSITION OF THE EC
NOW TRENDING CLOSER TO YESTERDAY`S GFS SOLUTION...AND HAVE LEANED
MORE HEAVILY TOWARDS THE GFS WITH THIS IN MIND.

AVIATION...CEILINGS WILL LOWER ACROSS THE AREA THROUGH THIS
EVENING AS A COLD FRONT CONTINUES TO MOVE TOWARD THE COAST. MVFR
CONDITIONS ALONG THE COAST WILL SPREAD INTO THE UMPQUA BASIN
THROUGH THIS EVENING. EXPECT OBSCURATIONS TO BE NEAR TOTAL ACROSS
THE COASTAL MOUNTAINS, SPREADING TO THE CASCADES, SISKIYOUS, AND
MARBLE MOUNTAINS THROUGH THIS EVENING. THERE IS A SLIGHT CHANCE OF
AFTERNOON AND EVENING THUNDERSTORMS OVER LAKE AND MODOC COUNTIES.
THIS EVENING EXPECT SOME IFR ALONG THE COAST AND MVFR IN THE
UMPQUA BASIN AS WELL AS IN NORTHWEST FLOW UPSLOPE AREAS ALONG AND
NEAR THE CASCADES AND SISKIYOUS. OTHERWISE VFR SHOULD PREVAIL.
OVERNIGHT PARTIAL CLEARING WILL OCCUR WITH PATCHY MVFR DISSIPATING
TO MOSTLY IN THE UMPQUA BASIN. IT WILL CLEAR TO VFR ALL AREAS
BETWEEN SUNRISE AND NOON ON SUNDAY AS HIGH PRESSURE BECOMES WELL
ESTABLISHED. BTL

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 11 AM
     SUNDAY TO 5 AM PDT TUESDAY FOR PZZ356.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 11 AM SUNDAY TO 5
     AM PDT TUESDAY FOR PZZ356.
     SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM SUNDAY TO 11 PM PDT
     MONDAY FOR PZZ350-370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 PM SUNDAY TO 11
     PM PDT MONDAY FOR PZZ350-370.
     SMALL CRAFT ADVISORY FOR WINDS FROM 5 AM TO 2 PM PDT SUNDAY FOR
     PZZ376.
     HAZARDOUS SEAS WARNING FROM 2 PM SUNDAY TO 11 PM PDT MONDAY FOR
     PZZ376.
     GALE WARNING FROM 2 PM SUNDAY TO 11 PM PDT MONDAY FOR PZZ376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 5 AM TO 2 PM PDT
     SUNDAY FOR PZZ376.

$$

MAS/MAS/JRS