797 FXUS66 KPQR 021120 AFDPQR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PORTLAND OR 317 AM PST SUN MAR 2 2014 .SYNOPSIS...COLD HIGH PRESSURE HAS SETTLED INTO THE COLUMBIA BASIN WITH LOWER PRESSURE THE OREGON COAST. AS A RESULT...EAST WINDS CONTINUE TO PUSH COLD AIR THROUGH THE COLUMBIA GORGE...COLD ENOUGH FOR WINTRY PRECIPITATION. TEMPERATURES ARE COLD ENOUGH FOR FREEZING RAIN IN FAR EASTERN PORTIONS OF THE PORTLAND METRO THIS MORNING. MILDER AIR WILL GRADUALLY PUSH IN AS LOW PRESSURE MOVES ONSHORE INTO WASHINGTON TONIGHT AND EARLY MONDAY. THIS SYSTEM WILL ALSO BRING GUSTY WINDS TO THE COAST AND WIDESPREAD RAIN ACROSS THE FORECAST AREA. A SERIES OF POTENT PACIFIC FRONTAL SYSTEMS WILL THEN KEEP THINGS WET AND WINDY AT TIMES FOR MUCH OF THE UPCOMING WEEK. && .SHORT TERM...TONIGHT THROUGH TUESDAY...A SIGNIFICANT SNOW AND ICE EVENT IS UNDERWAY IN THE COLUMBIA GORGE...AS TEMPERATURES ARE IN THE MID TO UPPER 20S. AS MOST MODELS SUGGESTED YESTERDAY MORNING...COLD HIGH PRESSURE HAS SETTLED INTO THE COLUMBIA BASIN WITH BRISK EASTERLY FLOW THROUGH THE GORGE. COLD...DRY AIR IS DEEP ENOUGH TO PRODUCE SNOW IN THE HOOD RIVER VALLEY FOR NOW. MEANWHILE THE COLD LAYER BECOMES THINNER THE FURTHER WEST ONE GOES THROUGH THE GORGE. AS A RESULT...FREEZING RAIN PREVAILS CASCADE LOCKS WESTWARD. TEMPERATURES HAVE BEEN FALLING SLOWLY BUT STEADILY THROUGH THE NIGHT IN EASTERN PORTIONS OF THE PORTLAND METRO AREA. CURRENTLY IT IS 31 DEGREES HERE AT THE OFFICE IN PARKROSE/NE PORTLAND. KTTD HAS REPORTED SEVERAL HOURS OF -FZRA...AND IT APPEARS TO BE ACCUMULATING ACCORDING TO THE ICE ACCRETION SENSOR. THE SENSOR IS SUGGESTING 0.15 INCH OF ICE HAS ACCUMULATED AT THE AIRPORT. OTHER ACCOUNTS SUGGEST ICE IS INDEED ACCUMULATING IN TROUTDALE AND GRESHAM...BUT NOT QUITE THAT MUCH. THE ICE ACCRETION SENSOR IS MADE OF METAL...SO IT REPRESENTS WHAT MAY BE ACCUMULATING ON THE COLDEST SURFACES. DESPITE TEMPS JUST BELOW FREEZING SINCE 10 PM...THE ONLY FREEZING WE HAVE SEEN IS A LITTLE BIT ON THE CARS IN OUR PARKING LOT AND METAL FENCES. THE ROADS REMAIN WET HERE...BUT THERE HAVE BEEN SOME REPORTS ON SOCIAL MEDIA THAT SURFACES ARE BECOMING SLICK IN TROUTDALE AND GRESHAM. SINCE TEMPERATURES ARE NOT EXPECTED TO WARM UP EARLY THIS MORNING...AND PRECIPITATION IS ONLY EXPECTED TO INCREASE...HAVE DECIDED TO ISSUE A FREEZING RAIN ADVISORY FOR THE PORTLAND METRO AREA NEAR THE GORGE UNTIL 10 AM. THIS HAS ALL THE MAKINGS OF A SUBSTANTIAL SNOW AND ICE EVENT IN THE GORGE...IN FACT THERE HAVE ALREADY BEEN SIGNIFICANT TRAVEL ISSUES WITH THE RATHER LIGHT AMOUNTS OF PRECIPITATION RECEIVED SO FAR. LOW PRESSURE IS STRENGTHENING NEAR 42N/134W...AND APPROACHING THE PAC NW COAST. THIS SYSTEM WILL ONLY SERVE TO PULL MORE COLD...DRY AIR FROM THE COLUMBIA BASIN INTO THE GORGE AS IT SPREADS STEADY RAIN ACROSS THE ENTIRE FORECAST AREA. LOOKING AT HIGHER RESOLUTION MODELS SUCH AS THE UW WRF-GFS AND OUR OWN 4 KM LOCAL WRF...AS WELL AS THE LOWER RESOLUTION 12 KM NAM AND ECMWF...IT APPEARS GRADIENTS REMAIN EASTERLY THROUGH THE GORGE INTO AT LEAST MIDDAY. THIS WILL SERVE TO LOCK THE COLD AIR IN PLACE IN THE HOOD RIVER VALLEY...S WA CASCADE VALLEYS... AND THE MOUNT ADAMS AREA WHILE THE HEAVIEST PRECIPITATION STARTS TO FALL LATER TODAY. GIVEN THE PRECIPITATION THAT HAS ALREADY FALLEN... AND THE SNOW AND ICE EXPECTED TODAY...FEEL A WINTER STORM WARNING IS WARRANTED FOR THESE AREAS AS WELL AS THE WEST AND CENTRAL COLUMBIA GORGE. ALSO DECIDED TO ADD A FREEZING RAIN ADVISORY FOR THE NORTH OREGON CASCADES...MAINLY FOR THE PASSES AND THE EAST SIDE OF MOUNT HOOD. THE CHANGEOVER TO PLAIN RAIN WILL LIKELY OCCUR SOMETIME THIS AFTERNOON IN THE WEST GORGE...BUT AREAS FURTHER EAST WILL PROBABLY NOT CHANGE OVER UNTIL THE UPPER TROUGH AXIS MOVES ACROSS THE CASCADES THIS EVENING. THIS WILL SWITCH THE SFC PRESSURE GRADIENT AND OPEN UP THE ENTIRE GORGE AND ADJACENT VALLEYS TO W-SW FLOW MONDAY...BRINGING MUCH MILDER AIR AND AN END TO THE THREAT OF WINTRY PRECIP. WILL NEED TO KEEP AN EYE ON RAINFALL TOTALS THIS WEEK...AS A SERIES OF FAIRLY MOIST SYSTEMS MOVES ACROSS THE PAC NW. EACH SYSTEM HAS THE POTENTIAL TO BRING 1-2 INCHES OF RAIN TO HIGHER TERRAIN...AND MODELS SHOW REASONABLE AGREEMENT ON BRINGING ONE THROUGH EVERY 24-36 HRS. IT APPEARS THE JUICIEST SYSTEM WILL COME MIDWEEK...AS MODELS SHOW IT HAVING A STRONG TAP TO SUBTROPICAL MOISTURE. IF RAINFALL AND FAIRLY HIGH SNOW LEVELS PAN OUT AS PRESENTLY EXPECTED...THERE COULD BE SOME HYDROLOGIC ISSUES BY THE END OF THE WEEK. WEAGLE .LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS... TUESDAY NIGHT THROUGH SATURDAY...MILD BUT WET CONDITIONS ARE EXPECTED NEXT WEEK AS STRONG WESTERLY FLOW PREVAILS. BOTH THE GFS AND ECMWF REMAIN IN FAIR AGREEMENT SHOWING BACK TO BACK SYSTEMS MOVING THROUGH THE REGION LATE TUESDAY AND ANOTHER LATE WEDNESDAY OR THURSDAY. THERE ARE SOME NOTABLE DIFFERENCES...PRIMARILY CONCERNING THE STRENGTH AND POSITION OF A SURFACE LOW WEDNESDAY NIGHT. THE ECMWF IS MAINTAINING A MORE ORGANIZED SURFACE LOW FARTHER SOUTH THAN THE GFS...SUPPORTING A CONTINUED CHANCE OF STRONG WINDS AT THE COAST AS THE LOW MOVES ONSHORE WEDNESDAY NIGHT. WET WEATHER WILL CONTINUE THROUGH LATE WEEK AS MODELS MAINTAIN AN UPPER LOW IN THE GULF OF ALASKA...WHICH WILL KEEP WESTERLY FLOW INTO THE PAC NW. THERE MAY BE A BRIEF BREAK IN THE RAIN ON FRIDAY AS UPPER LEVEL HIGH PRESSURE NOSES IN...BUT THE ALASKAN GULF LOW LOOKS TO PRECLUDE ANY PERSISTENCE IN THE RIDGING. LASTLY...AT THIS TIME THERE IS SOME POTENTIAL FOR CONVECTION TUESDAY NIGHT THROUGH THURSDAY...PRIMARILY FOR THE NORTHERN PORTIONS OF THE CWA. BB && .AVIATION...NOT A GREAT DAY FOR FLYING IN THE REGION. WIDESPREAD MVFR WITH POCKETS OF IFR WILL CHANGE LITTLE AS WARM FRONT LIFTS ACROSS REGION LATER TODAY. MTNS REMAIN OBSCURED. LIGHT RAIN WILL INCREASE AFTER 18Z FROM THE SW. AREAS OF IFR CIGS OVER THE INTERIOR WILL IMPROVE A BIT...BUT WILL REMAIN MVFR. WORST WEATHER REMAINS IN COLUMBIA GORGE AND EASTWARD...WHERE OCCASIONAL -FZRA WILL CONTINUE INTO THE EVENING. ONCE FRONT LIFTS N THIS EVENING... CIGS WILL GRADUALLY IMPROVE TO LOW VFR TONIGHT. KPDX AND APPROACHES...LITTLE CHANGE IN CIGS TODAY. WARM FRONT WILL PUSH INCREASING RAIN INTO AREA AFTER 16Z. CIGS WILL GRADUALLY IMPROVE TO LOW VFR AFTER 04Z AS WARM FRONT LIFTS N OF KPDX. WILL HAVE OCCASIONAL FREEZING RAIN BELOW 4000 FT IN E APPROACHES THROUGH 20Z. ROCKEY. && .MARINE...WARM FRONT WILL LIFT N ACROSS REGION TODAY AND THIS EVENING. WILL SEE INCREASING S WINDS BEHIND THE FRONT...WITH GUSTS 30 TO 35 KT AT TIMES. WITH WIND CHOP...COMBINED SEAS WILL BUILD UP TO 8 TO 9 FT. WINDS RELAX LATER TONIGHT AS GRADIENT WEAKENS A BIT. THE NEXT SIGNIFICANT FRONT ARRIVES LATE TUE INTO WED...WITH GOOD POTENTIAL FOR SOUTHERLY GALES. UNSETTLED PATTERN CONTINUES THIS WEEK WITH MORE FRONTS ARRIVING...WITH WINDS 25 TO 35 KT AT TIMES AND SEAS RUNNING 9 TO 12 FT. ROCKEY. && .PQR WATCHES/WARNINGS/ADVISORIES... OR...WINTER STORM WARNING UNTIL 4 PM PST THIS AFTERNOON FOR WESTERN COLUMBIA RIVER GORGE. FREEZING RAIN ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER PORTLAND METRO AREA NEAR THE GORGE. WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR CENTRAL COLUMBIA RIVER GORGE-UPPER HOOD RIVER VALLEY. FREEZING RAIN ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR NORTHERN OREGON CASCADES. WA...WINTER STORM WARNING UNTIL 4 PM PST THIS AFTERNOON FOR WESTERN COLUMBIA RIVER GORGE. FREEZING RAIN ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER VANCOUVER AREA NEAR THE GORGE. WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR CENTRAL COLUMBIA RIVER GORGE-SOUTH WASHINGTON CASCADES. PZ...GALE WARNING UNTIL 3 AM PST MONDAY FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 8 AM PST THIS MORNING. SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 3 PM THIS AFTERNOON TO 8 PM PST THIS EVENING. && $$ MORE WEATHER INFORMATION ONLINE AT.. HTTP://WEATHER.GOV/PORTLAND INTERACT WITH US VIA SOCIAL MEDIA WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV WWW.TWITTER.COM/NWSPORTLAND 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.