AREA FORECAST DISCUSSION

 
 FXUS66 KMFR 220548
 AFDMFR
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE MEDFORD OR
 902 PM PST SAT NOV 21 2009
 
 .DISCUSSION...TIGHT...RAPIDLY DEVELOPING DEEP SURFACE LOW MOVING
 QUICKLY TOWARD THE NORTHERN OREGON COAST. NAM POSITION SLIGHTLY 
 TOO FAR NORTH AND EAST. EXPECT THE TRACK TO BE SOUTH OF NAM
 FORECAST POSITION. CURRENT FORECASTS TAKE THIS INTO ACCOUNT AND
 LOOK GOOD. STORM FORCE WINDS ALREADY IN THE OUTER WATERS NORTH
 OF THE CAPE AND WINDS SHOULD COME UP RAPIDLY IN THE NEXT 3 HOURS
 ALONG THE COAST. PROGS SHOW THE WEATHER SETTLING DOWN SUNDAY AND
 MONDAY...THEN HIGH PRESSURE DOMINATING UNTIL THE END OF NEXT WEEK.
 NO UPDATES NEEDED THIS EVENING.
 
 
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 .AVIATION...CURRENT VFR CEILINGS WILL BE SHORT-LIVED AS THE
 OFFSHORE FRONT DROPS CEILING TO MVFR IN LOW CLOUDS AND SHOWERS IN
 THE NEXT FEW HOURS. COASTAL TERMINALS WILL LIKELY BE IMPACTED BY
 LOW LEVEL WIND SHEAR WITH GUSTY WINDS TO 35KT BUT EVEN STRONGER
 50-60KT WINDS JUST ABOVE THE SURFACE. STRONG WINDS WILL ALSO
 IMPACT THE CASCADES AND THE EAST SIDE LATE TONIGHT AND SUNDAY
 MORNING. MOUNTAINS AND EAST SIDE WILL HAVE SNOW LATE TONIGHT AND
 SUNDAY MORNING...REDUCING VISIBILITIES. MOUNTAIN OBSCURATION WILL
 BE WIDESPREAD BY TONIGHT THROUGH SUNDAY AS DEEP MOISTURE PUSHES
 INTO THE REGION.
 
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 .PREV DISCUSSION... /ISSUED 301 PM PST SAT NOV 21 2009/ 
 
 DISCUSSION...QUICK-MOVING DEVELOPING FRONTAL SYSTEM WILL IMPACT
 THE CWA TONIGHT THROUGH SUNDAY MORNING. THE MAIN IMPACTS WILL BE
 STRONG WINDS AND SOME SNOW OVER THE CASCADES AND THE EAST SIDE.
 THE FAST MOVEMENT OF THIS SYSTEM...ALONG WITH MORE WESTERLY
 WINDS...WILL FAVOR THE CASCADES RECEIVING MORE SNOWFALL AND THE
 MOUNT SHASTA AREA RECEIVING LESS THAN THE PREVIOUS STORM. MODELS
 HAVE SETTLED ON A 990MB LOW CENTERED WEST OF THE WA/OR BORDER LATE
 TONIGHT. THE STRONGEST WINDS WILL IMPACT COASTAL WATERS AND
 COASTAL ZONES TONIGHT...WITH WINDS AFFECTING THE CASCADES THROUGH
 THE EAST SIDE LATE TONIGHT THROUGH SUNDAY MORNING. VERY STRONG H8
 FLOW OF 50KT IS NOTED OVER NORTHWESTERN PORTION OF THE CWA LATE
 TONIGHT...BUT STABILITY SHOULD KEEP MOST OF THIS AREA FROM GETTING
 ADVISORY LEVEL WINDS. THIS SITUATION MAY NEED TO BE LOOKED AT
 DURING THE LATE AFTERNOON. SIGNIFICANT SNOW WILL FALL DURING A
 SHORT PERIOD BETWEEN TONIGHT AND TOMORROW MORNING. A FOOT IS
 POSSIBLE IN THE HIGHER TERRAIN OF THE CASCADES WITH SEVERAL INCHES
 EXPECTED EAST OF THE CASCADES IN KLAMATH COUNTY. ON SUNDAY IN THE
 POSTFRONTAL ENVIRONMENT EXPECT SNOW SHOWERS ABOVE 3500 FEET AND
 RAIN SHOWERS IN THE LOWER ELEVATIONS. RIDGING WILL BUILD OVER THE
 REGION SUNDAY NIGHT...ESSENTIALLY ENDING THE PRECIPITATION OVER
 THE CWA.
 
 MODELS HAVE BEEN VERY PERSISTENT WITH UPPER RIDGING FROM MONDAY
 THROUGH WEDNESDAY OVER NORTHERN CA AND SOUTHWESTERN OR...WITH THE
 RESULTANT WEATHER IMPACTS BEING MORNING FOG MONDAY THROUGH
 WEDNESDAY IN THE FAVORED LOW ELEVATION AREAS LIKE THE ROGUE AND
 ILLINOIS VALLEYS...AND THE UMPQUA BASIN. A WEAK WARM FRONT BRUSHES
 THE COAST ON WEDNESDAY BUT WILL NOT LIKELY RESULT IN ANY
 SIGNIFICANT PRECIPITATION.  GFS AND ECMWF BOTH PUT AN END TO THE
 DRY WEATHER ON THANKSGIVING DAY BUT THEIR SOLUTIONS ARE STILL
 FAIRLY DIFFERENT. THERE ARE STILL UNKNOWNS REGARDING THE FORECAST
 FOR THURSDAY...BUT AT THIS POINT IT SEEMS REASONABLE TO EXPECT
 LIGHT SNOW IN THE MOUNTAINS AND LIGHT RAIN IN THE VALLEYS ON LATE
 THURSDAY. IT STILL SEEMS THERE WILL NOT BE A LARGE STORM FOR
 THANKSGIVING DAY TRAVELERS IN THE REGION.
 
 
 .MFR WATCHES/WARNINGS/ADVISORIES...
 OR...WINTER WEATHER ADVISORY UNTIL 7 AM PST SUNDAY FOR ORZ027-ORZ028-
      ORZ029-ORZ030.
      WIND ADVISORY UNTIL 7 AM PST SUNDAY FOR ORZ031.
      HIGH WIND WARNING UNTIL 4 AM PST SUNDAY FOR ORZ021-ORZ022.
 
 CA...WIND ADVISORY UNTIL 4 AM PST SUNDAY FOR CAZ081.
 
 PACIFIC COASTAL WATERS...STORM WARNING UNTIL 4 AM PST SUNDAY FOR 
      PZZ350-PZZ370.
      HAZARDOUS SEAS WARNING UNTIL 4 AM PST MONDAY FOR PZZ350-PZZ356-
      PZZ370-PZZ376.
      GALE WARNING UNTIL 4 AM PST SUNDAY FOR PZZ356-PZZ376.
 
 $$
 
 DDG