000
FXUS66 KPQR 280457
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
856 PM PST MON DEC 27 2010
.SYNOPSIS...WET WEATHER TO CONTINUE...ALONG WITH SOME WINDY
CONDITIONS TONIGHT INTO TUE. THEN TURNING COLDER WED...WITH SOME
THREAT OF SNOW...EVEN DOWN TO INTERIOR VALLEY FLOORS POSSIBLY. LATER
PART OF THE WEEK WILL FOCUS ON COLDER WEATHER...AND MAYBE A BIT OF
OCCASIONAL RAIN OR SNOW...DEPENDING ON ELEVATION.
&&
.SHORT TERM...MY DISCUSSION WAS CONSUMED BY THIS LOVELY COMPUTER.AN
ABBREVIATED VERSION FOLLOWS WITH THE PREVIOUS DISCUSSION ATTACHED.
REALLY NOT A WHOLE LOT OF CHANGE...WET AND WINDY TONIGHT. RAISED A
LOW END HIGH WIND WARNING FOR POTENTIAL TO MIX SOME STRONGER WINDS TO
THE SURFACE ALONG THE COAST. MOST ENERGY SAGS SOUTH INTO TOMORROW. AN
INVIGORATED SYSTEM WILL JET INTO THE SOUTHERN OREGON COAST ON TUESDAY
EVENING BRINGING A GOOD DOSE OF RAIN AND SNOW TO THE HIGHER
ELEVATIONS. BY WEDNESDAY MORNING...COLD AIR FILTERS IN AND THERE IS
SOME POTENTIAL FOR SNOW TO THE VALLEY FLOOR THOUGH QPF LOOKS LIGHT
THUS ACCUMULATIONS IF ANY SHOULD BE LIGHT...THEN SOME DRYING FOR
FRIDAY.
PREVIOUS DISCUSSION FOLLOWS...
WARM ADVECTION PATTERN WITH LIGHT RAIN WILL CONTINUE
TONIGHT AND INTO TUE. RAIN WILL INCREASE IN INTENSITY LATER THIS
EVENING. CURRENT SNOW LEVELS ARE NEAR 2500 FEET...AND WILL RISE
SLOWLY TONIGHT. MAIN WAVE RESPONSIBLE WILL PASS TO OUR NW LATER THIS
EVENING...ALLOWING FOR THICKNESSES TO JUMP. THIS WILL PUSH SNOW LEVEL
UP TO 4000 TO 5000 FEET LATER TONIGHT. UNTIL THEN...SHOULD SEE QUITE
A BIT OF SNOW PILE UP IN THE CASCADES. CURRENTLY HAVE WINTER STORM
WARNING TONIGHT INTO TUE FOR THE CASCADES...WHERE 15 TO 24 INCHES CAN
BE EXPECTED. HEAVIEST WILL FALL JUST ABOVE PASS LEVELS.
OTHERWISE...APPEARS TO BE TYPICAL LATE DECEMBER WEATHER ON TAP FOR
TONIGHT AND TUE...WITH RAIN AND EVEN BREEZY CONDITIONS. WILL BE
BREEZY ON THE COAST WHERE DECENT GRADIENTS WILL POP GUSTS OF 45 TO 55
MPH...MAINLY ON THE HEADLANDS. WINDS GRADUALLY COME DOWN ON TUE.
RAIN FALLS ELSEWHERE. COULD BE HEAVY AT TIMES TONIGHT ON THE COAST
INTO THE COAST RANGE...WHERE TOTALS OF 2 TO 3 INCHES ARE EXPECTED.
NO FLOODING EXPECTED...BUT SEVERAL RIVERS BEGIN TO PUSH BANKFULL BY
LATE TUE AFTERNOON AND TUE NIGHT.
THIS FRONTAL BOUNDARY WILL BE SLOW TO PUSH INLAND ON TUE. IN FACT
MODELS HINTING AT ANOTHER WAVE THAT FORMS ON THE FRONT OFF THE S
OREGON COAST LATE TUE. THIS IS THE ONE THAT WILL BE INTERESTING. THIS
WAVE WILL MOVE ONSHORE LATER TUE EVENING...THEN UP AND ACROSS THE SW
OREGON INTO N CENTRAL OREGON LATER TUE NIGHT. THIS WILL KEEP RAIN
ACROSS THE REGION INTO TUE EVENING. HOWEVER...ONCE THIS LOW MOVES
PAST...COLD FRONT WILL DROP IN FROM THE NW LATER TUE NIGHT. THIS COLD
FRONT WILL BRING MUCH COLDER TEMPERATURES...ALONG WITH BREEZY W TO NW
WINDS TO THE REGION. AIR MASS TURNS COLD ENOUGH ON WED TO SUPPORT
SNOW SHOWERS. HOWEVER...FOR THE LOWLANDS...NOT AN IDEAL SET UP AS NW
FLOW USUALLY DOES NOT BODE WELL FOR STICKING SNOWS IN THE LOWLANDS.
STILL...WILL SEE MINOR ACCUMULATIONS IN MANY AREAS...BUT BEST THREAT
OF 1-INCH PLUS WILL BE ON THE HIGHER HILLS AND OF COURSE THE
MOUNTAINS OF BOTH COAST AND CASCADES RANGES.
TEMPERATURES TURNING COLDER...WITH HIGHS IN THE 30S TO LOWER 40S FOR
WED AND THU...WITH LOWS IN THE MID TO UPPER 20S IN THE INTERIOR
LOWLANDS FOR WED NIGHT. WILL BE COLDER IN THE CASCADES. HAVE ISSUED
A SPS FOR THIS COMING COLDER AND WINTERY WEATHER.ROCKEY.
.LONG TERM...SURFACE HIGH PRESSURE BEGINS BUILDING OVER THE COASTAL
WATERS STARTING THU AFTERNOON...AND WILL PRETTY MUCH ENVELOP
THE REGION THROUGH FRIDAY. MODELS REMAIN CONSISTENT IN SHOWING COLD
HIGH PRESSURE DROP DOWN FROM BRITISH COLUMBIA AND DIG FURTHER INTO
THE MIDWEST. SEVERAL SHORTWAVES WILL TRAVEL UP AND OVER THE RIDGE IN
THE NORTH FLOW...BUT THE OVERLAND TRAJECTORY WOULD LIMIT ANY
SIGNIFICANT PRECIPITATION LATE THURSDAY. HAVE LOWERED POPS ONCE
AGAIN AS MODELS SHOW OFFSHORE FLOW RETURNING TO THE PACIFIC
NORTHWEST THURSDAY NIGHT AND EARLY FRIDAY. THIS WILL SWEEP COLD AIR
FROM THE CONTINENTAL HIGH PRESSURE INTO THE AREA...SO HAVE KEPT
TEMPERATURES ON THE COLDER SIDE. HIGHS WILL REMAIN IN THE LOWER 40S
WHILE LOWS FLIRT IN THE UPPER 20S FOR THE BEGINNING OF THE EXTENDED
PERIOD. LATEST MODEL RUNS HAVE INCREASED THE CHANCE OF POPS IN THE
CWA FOR FRIDAY...GIVEN THE COLDER TEMPERATURES AND MORE PRECIP...
YET ANOTHER SNOW EVENT MAY BE POSSIBLE. WILL BE FOCUSED ON WHAT
HAPPENS WHEN THE NEXT WEATHER SYSTEM ENCOUNTERS THE COLDER
ENVIRONMENT FRIDAY. OTHERWISE...THE REMAINDER OF THE PERIOD LOOKS
RATHER SEASONAL. LR
&&
.AVIATION...MVFR/IFR CONDITIONS SHOULD PREVAIL TONIGHT IN HEAVY
RAINFALL BEHIND A WARM FRONT THAT HAS PUSHED THROUGH THE REGION
TODAY. IFR CONDITIONS LIKELY FOR THE COASTAL LOCATIONS...BUT ALSO
POSSIBLE INLAND DURING PERIODS OF HEAVIER RAIN. A SLOW MOVING COLD
FRONT WILL BEGIN TO PUSH ONSHORE EARLY TOMORROW MORNING...BRINGING
CONTINUED RAIN AND MVFR/IFR CONDITIONS TO THE REGION FOR MUCH OF
TOMORROW. BRISK GUSTY SOUTH WINDS ARE EXPECTED ALONG THE COAST
TONIGHT INTO EARLY TOMORROW MORNING.
KPDX AND APPROACHES...MVFR CONDITIONS WITH SOME LOCAL IFR CIGS AND
VISIBILITIES POSSIBLE DURING PERIODS OF HEAVIER RAIN TONIGHT AND
TOMORROW MORNING. CONDITIONS WILL REMAIN MVFR A GOOD PART OF TUESDAY
WITH PRECIPITATION DECREASING IN THE AFTERNOON. JFP
&&
.MARINE...A SURFACE LOW PASSING JUST NORTH OF THE COASTAL WATERS
TONIGHT WILL BRING GALE FORCE WINDS THROUGH THE REMAINDER OF THE
EVENING. THE WINDS SHOULD BEGIN TO DROP AFTER THE TRAILING COLD FRONT
MOVES ACROSS THE WATERS AND INLAND LATE TONIGHT IN THE NORTH AND
AROUND SUNRISE TOMORROW IN THE SOUTH. WINDS WILL EASE SOME TUESDAY
BEFORE INCREASING TO HIGH END SMALL CRAFT LEVELS OR EVEN POSSIBLY
GALE FORCE BY WEDNESDAY AS A COLDER SYSTEM DROPS IN FROM THE
NORTH. SEAS WILL RISE INTO THE MID TEENS TONIGHT...BRIEFLY DROPPING
TO
CLOSE TO 10 FT LATE TUESDAY AND EARLY TUESDAY NIGHT. SEAS WILL
INCREASE WITH THE INCREASING NORTHERLY WINDS WEDNESDAY AND MAY GET
CLOSE TO 20 FT IF THE GALES DEVELOP. PT/JFP
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WARNING UNTIL 10 PM PST TUESDAY FOR CASCADES IN
LANE COUNTY-NORTHERN OREGON CASCADES.
HIGH WIND WARNING UNTIL 1 AM PST TUESDAY FOR CENTRAL OREGON
COAST.
HIGH WIND WARNING UNTIL 10 PM PST THIS EVENING FOR NORTH OREGON
COAST.
WA...WINTER STORM WARNING UNTIL 10 PM PST TUESDAY FOR SOUTH
WASHINGTON CASCADES.
PZ...GALE WARNING UNTIL 2 AM PST TUESDAY FOR COASTAL WATERS FROM CAPE
SHOALWATER WA TO CASCADE HEAD OR OUT TO 60 NM.
GALE WARNING UNTIL 7 AM PST TUESDAY FOR COASTAL WATERS FROM
CASCADE HEAD TO FLORENCE OR OUT TO 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 3 PM PST
TUESDAY.
&&
$$
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.
