AREA FORECAST DISCUSSION

 
 FXUS66 KMFR 241623
 AFDMFR
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE MEDFORD OR
 823 AM PST TUE NOV 24 2009
 
 .DISCUSSION...
 NO UPDATE TO THE FORECAST THIS MORNING AS THE INHERITED FORECAST
 IS WELL ON TRACK. WE ARE EXPECTING A DRY AND MOSTLY CLEAR DAY
 TODAY AS A 500 HPA RIDGE AXIS BUILDS OVER OREGON FROM THE
 SOUTHWEST. THE NEXT CHANCE OF RAIN IS THURSDAY NIGHT IN
 ASSOCIATION WITH A SURFACE COLD FRONT WHICH IS ALREADY ADDRESSED IN
 THE GRIDS.
 
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 .AVIATION...
 VISIBLE SATELLITE IMAGERY DEPICTS LOW CLOUDS AND FOG IN THE ILLINOIS
 VALLEY AND INTO THE UMPQUA BASIN. A BROKEN 8KFT CLOUD DECK WAS
 HANGING AROUND EARLY THIS MORNING ACROSS THE SOUTHERN ROGUE VALLEY
 AND EXTENDING EASTWARDS ACROSS THE HIGH DESERTS. THIS CLOUD DECK
 HELPED TO INHIBIT FOG FORMATION IN THE ROGUE VALLEY THIS MORNING.
 ELSEWHERE...ALL IS QUITE FOR THE FA THIS MORNING. EXPECT VFR
 CONDITIONS TO CONTINUE TODAY WITH IFR CONDITIONS RETURNING TONIGHT
 AND CONTINUING THROUGH THE EARLY MORNING HOURS FOR THE WESTERN
 VALLEYS IN ASSOCIATION WITH AREAS OF FOG AND REDUCED VISIBILITIES.
 MVFR CONDITIONS ARE POSSIBLE FOR THE EAST OF THE CASCADES IN
 ASSOCIATION WITH ICE FOG FOR THE MORNING.
 
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 .PREV DISCUSSION... /ISSUED 317 AM PST TUE NOV 24 2009/ 
 
 DISCUSSION...OFFSHORE FLOW PATTERN IN PLACE OVER THE NEXT SEVERAL
 DAYS AS UPPER LEVEL RIDGE BUILDS OVER THE PACIFIC NORTHWEST. WITH
 THIS PATTERN RIDGES WILL REMAIN RELATIVELY WARM AN DRY OVER THE
 NEXT SEVERAL NIGHTS WITH FOG IN THE WEST SIDE VALLEYS AND THE
 KLAMATH FALLS AREA. STRONG INVERSION OVERNIGHT WITH THE MORNING FOG
 WILL KEEP TEMPERATURES BELOW WHAT 850 TEMPERATURES WOULD SUPPORT.
 UPPER LEVEL RIDGE NUDGES EAST BY THURSDAY AHEAD OF THE NEXT SYSTEM
 THAT MOVES ONSHORE THURSDAY MORNING. A PERTURBATION IN THE JET
 PATTERN AS UPPER TROUGH DEEPENS IN THE EASTERN PACIFIC AHEAD OF
 THE SYSTEM APPROACHING THE COAST DRAGS THE ENTRANCE REGION OF THE
 JET ACROSS THE HAWAIIAN ISLANDS...POSSIBLY BRINGING A TROPICAL TAP
 TO THE SYSTEM. CURRENT MODELS ARE PICKING UP ON THIS...BUT THE
 ACTUAL TROPICAL MOISTURE FEED INFLUENCE WILL HAVE TO BE CLOSELY
 MONITORED AS WE GET CLOSE TO THE SYSTEM MOVING THROUGH TO SEE HOW
 MUCH IS ACTUALLY PULLED INTO THE SYSTEM. THIS SYSTEM IS LOOKING TO
 HAVE BRIEFLY STRONG WINDS ACCOMPANYING THE HEAVY RAIN AS THE FRONT
 MOVES ONSHORE BUT POSSIBLY STRONG WINDS ARE MORE PROLONGED EAST OF
 THE CASCADES AHEAD OF THE FRONT WITH SW 700 MB WINDS OF 50 TO 60
 KT...DEPENDING ON THE MODEL. 
 
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 .MFR WATCHES/WARNINGS/ADVISORIES...
 OR...NONE.
 
 CA...NONE.
 
 PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS 
      UNTIL 10 PM PST THIS EVENING FOR PZZ350-PZZ356-PZZ370-
      PZZ376.
 
 

 
 KS