Issued by NWS Portland, OR
000 FXUS66 KPQR 220442 AFDPQR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PORTLAND OR 841 PM PST SAT NOV 21 2009 .SYNOPSIS...A STRONG PACIFIC COLD FRONT WILL MOVE INLAND OVERNIGHT AS A DEEP SURFACE LOW OFF THE COAST MOVES NORTHEAST INTO WASHINGTON. A WEAK RIDGE OF HIGH PRESSURE WILL FOLLOW SUNDAY AFTERNOON AND NIGHT...BEFORE THE NEXT FRONTAL SYSTEM ARRIVES LATER ON MONDAY. && .SHORT TERM...MODELS ARE IN REASONABLY GOOD AGREEMENT SHOWING THE DEEP SURFACE LOW MOVING ONTO THE CENTRAL WA COAST OR POSSIBLY A BIT S AROUND 09Z. HOWEVER AT 00Z MODELS WERE ABOUT 4 MB TOO HIGH COMPARED WITH SHIP REPORTS W OF 130W NEAR THE LOW. MODELS ARE IN GOOD AGREEMENT ON THE UPPER FEATURES...WITH A STRONG SHORTWAVE MOVING ACROSS THE FORECAST AREA TONIGHT...DIGGING SLIGHTLY TO THE ESE. TIMING OF THE COLD FRONT IN ALL MODELS INDICATES FRONTAL PASSAGE ON THE COAST AROUND MIDNIGHT. HAVE ISSUED A HIGH WIND WARNING FOR THE WILLAPA HILLS TO GO ALONG WITH THE COASTAL WARNING AND INLAND VALLEY WIND ADVISORIES. WINDS INLAND LOOK GUSTY WITH THE FRONT BUT ESPECIALLY AFTER THE FRONT AND LOW MOVE INLAND AS THERE WILL BE STRONG PRES RISES IN THE OVERNIGHT HOURS. DOPPLER RADAR SHOWS THE PRECIP FIELD HAS FINALLY SPREAD TO THE CASCADES THIS EVENING. WILL CONTINUE THE WINTER STORM WARNING FOR THE CASCADES AS MOISTURE...STRENGTH OF THE FRONT AND THE POST FRONTAL WESTERLY OROGRAPHIC FLOW ALL FAVOR SIGNIFICANT SNOWFALL FOR LATER TONIGHT AND SUN. A WEAK UPPER RIDGE WILL BUILD OVER THE FORECAST AREA SUN NIGHT AND MON FOLLOWING THE FRONT. BEST CHANCES FOR PRECIP MON AND TUE WILL SHIFT N INTO WA WITH WARM FRONT OVERRUNNING. THE UPPER RIDGE HOLDS COLD FRONT AT BAY UNTIL AFTER TUE NIGHT. RW .LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...WEAK HIGH PRES RIDGE OVER THE FORECAST AREA CONTINUES TO PUSH ENERGY NORTH OF FORECAST AREA MID WEEK. IT MANAGES TO DELAY THE ARRIVAL OF A SECOND SYSTEM THROUGH THUR. MODEL SOLUTIONS DIVERGE TOWARD THE END OF THE WEEK AND HAVE LITTLE CONFIDENCE IN THEM. AT THIS TIME WILL GO WITH CLIMATOLOGY UNTIL THERE IS SOME CONSISTENCY BETWEEN THE MODELS.. && .AVIATION...AREAS OF MVFR CONDITIONS ALONG THE COAST THIS EVENING WILL EXPAND INLAND TONIGHT AS THE RAIN SHIELD FROM THE NEXT STRONG SYSTEM APPROACHES. SOUTH WINDS WILL INCREASE THROUGH 09Z AND THEN TURN WESTERLY FROM WEST TO EAST AS THE ASSOCIATED STRONG COLD FRONT SWINGS ACROSS THE AREA. A MIX OF VFR AND MVFR CONDITIONS ARE EXPECTED SUNDAY MORNING IN STRONG UNSTABLE ONSHORE FLOW. KPDX AND APPROACHES...VFR CONDITIONS ARE EXPECTED THROUGH 06Z...THEN MVFR CONDITIONS WILL DEVELOP AS A COLD FRONT APPROACHES. SOUTH TO SOUTHWEST WINDS MAY BECOME QUITE STRONG AROUND 12Z AS A STRONG GRADIENT DEVELOPS OVER THE NORTH VALLEY AS THE LOW MOVES INLAND. WIND GUSTS NEAR 50 MPH ARE POSSIBLE. A MIX OF VFR AND MVFR CONDITIONS ARE EXPECTED SUNDAY MORNING IN STRONG UNSTABLE ONSHORE FLOW. && .MARINE...GALE FORCE SOUTH WINDS WILL STRENGTHEN TO STORM FORCE LATER THIS EVENING AS A POTENT LOW MOVES NORTH OF THE COASTAL WATERS AND INLAND ALONG THE WASHINGTON COAST. WINDS WILL TURN W TO NW ON SUNDAY AND BEGIN EASING. SEAS TONIGHT WILL LIKELY PEAK AROUND 20 FT ...BUT WILL DROP QUICKLY TO THE MID TEENS ON SUN. && .PQR WATCHES/WARNINGS/ADVISORIES... WA/OR...STORM WARNING FOR THE COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE THROUGH 3 AM SUNDAY MORNING. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR CONDITIONS THROUGH SUN EVENING. WINTER STORM WARNING FOR THE S WA AND N AND CENTRAL OREGON CASCADES TONIGHT AND SUNDAY. HIGH WIND WARNING FOR THE S WA/N AND CENTRAL OREGON COAST... AND WILLAPA HILLS TONIGHT. WIND ADVISORY FOR THE WILLAMETTE VALLEY...THE LOWER COLUMBIA...AND THE I-5 CORRIDOR FOR THIS EVENING THROUGH SUNDAY MORNING. && $$ MORE WEATHER INFORMATION ONLINE AT... HTTP://WEATHER.GOV/PORTLAND THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY REFERRED TO AS THE FORECAST AREA.
