Wildfire in Oregon, August 11 to 31, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
345 PM PDT MON AUG 11 2014

.SYNOPSIS...AN UPPER LEVEL LOW OFF THE N CA COAST WILL CONTINUE
TO SPREAD AN UNSTABLE AIR MASS N THROUGH THE REGION TONIGHT. AS
ANOTHER TROUGH OF LOW PRES APPROACHES THE COAST TUE...THE CA LOW
WILL WEAKEN AND LIFT N. THE SECOND LOW WILL SLOWLY MOVE E ACROSS
OREGON TUE THROUGH THU BRINGING A MOIST AND CONTINUED UNSTABLE AIR
MASS TO THE REGION AS WELL AS COOLER AIR. DRIER WEATHER LOOKS TO
RETURN AT THE END OF THE WEEK AS HIGH PRES PUSHES THE LOW E.
&&

.SHORT TERM...SPC MESOANALYSES SHOW AIR MASS DESTABILIZING OVER NW
OREGON THIS AFTERNOON...WITH MOST UNSTABLE CAPE OVER 1000 J/KG EARLY
THIS AFTERNOON...AND MID LEVEL LAPSE RATES OVER 8 C/KM. SATELLITE
AND RADAR IMAGES SHOWED CONVECTION INCREASINGING OVER FAR SOUTHERN
OREGON AND FURTHER S...LIFTING NNW AHEAD OF THE CUTOFF LOW OFF THE
CA COAST. THIS CONTINUES TO APPEAR TO FAVOR CONVECTION LATER TODAY
AND TONIGHT DEVELOPING OVER AND MOVING UP INTO THE FORECAST AREA...
SO WILL STICK WITH THE THUNDERSTORMS LIKELY FORECAST TONIGHT. THE
DRY LOW LEVELS SEEN IN THE 12Z SLE SOUNDING RESEMBLES AN INVERTED V
THAT IS FAVORABLE FOR GUSTY WINDS WITH THE STORMS. SURFACE ANALYSIS
EARLY THIS AFTERNOON SHOWED THE THERMAL INDUCED TROUGH OVER THE
COAST RANGE...WHICH HAS TURNED THE FLOW ONSHORE OVER MOST OF THE
COAST. AS THIS MOVES INLAND WILL SEE A SW ONSHORE FLOW DEVELOP OVER
MOST THE FORECAST AREA TONIGHT.

THE REMNANTS OF THE CA LOW ARE FORECAST BY MODELS TO LIFT N TUE...AS
THE NEXT5 LOW CUTS OFF AND DEEPENS OFF THE S OREGON COAST. THIS
LEAVES MUCH OF THE REGION STILL IN A SE FLOW ALOFT...WITH BUFR
SOUNDINGS AGAIN SHOWING INSTABILITY ALOFT OVER INLAND AREAS...AS
WELL AS GOOD DIVERGENCE UP AT 250 MB. WILL CONTINUE WITH CHANCES FOR
THUNDERSTORMS OVER ALL BUT THE COASTAL AREAS TUE...EVENTUALLY
SHIFTING THE THREAT FOR STORMS PRIMARILY TO THE CASCADES TUE NIGHT
AS THE LOW REACHES THE COAST. THIS SYSTEM...COMING OFF THE PACIFIC
AND HAVING POSSIBLY INGESTED SOME TROPICAL MOISTURE IN THE PAST FEW
DAYS IS MOISTER THAN THE AIR MASS CURRENTLY IN PLACE. WITH THE LOW
CUTTING A TRACK ACROSS WESTERN OREGON WED WILL BUM UP POPS TO LIKELY
CATEGORY MOST AREAS. ALTHOUGH AN ISOLATED STRIKE MAY YET BE POSSIBLE
WED...IT LOOKS LIKE A MOIST CLOUDY DAY WITH MARGINAL INSTABILITY AT
BEST SO WILL CARRY WORDING FOR SHOWERS AND OMIT THE MENTION OF
THUNDER. TEMPS WILL ALSO CONTINUE TO COOL AS DEEPER MARINE AIR WILL
BE IN PLACE.

THU THE UPPER LOW IS FORECAST TO SLOWLY PULL E OF THE REGION...SO
WILL SEE A DECREASING THREAT FOR SHOWERS BUT A CONTINUATION OF
COOLER THAN NORMAL TEMPS.

.LONG TERM...TROUGH OVER THE PACIFIC NORTHWEST WILL PROGRESS OFF TO
THE EAST THURSDAY NIGHT INTO FRIDAY...CAUSING ANY REMAINING RAIN TO
END ACROSS OUR AREA LATE THURSDAY NIGHT. A FAIRLY ZONAL FLOW PATTERN
SETS UP OVER OUR REGION BEHIND THIS SYSTEM. COOLER WEATHER WILL
RESULT FROM THIS PATTERN...WITH NORTHWESTERLY LOW-LEVEL WINDS
BRINGING TEMPERATURES A LITTLE BELOW NORMAL OVER THE WEEKEND. MODELS
ARE INDICATING THAT A SYSTEM COULD AFFECT OUR AREA AS EARLY AS
SUNDAY...BUT THE UNCERTAINTY IS GREAT DUE TO THE NATURE OF THIS TYPE
OF FLOW REGIME AND HOW FAR OUT IT IS IN THE FORECAST PERIOD. -MCCOY
&&

.FIRE WEATHER...ANOTHER HOT...DRY...AND VERY UNSTABLE DAY TODAY WITH
HAINES 6 CONDITIONS COMMON ACROSS SOUTHWEST WASHINGTON AND NORTHWEST
OREGON. THE UPPER LEVEL RIDGE INITIALLY RESPONSIBLE FOR THE HEAT IS
MOVING NORTHEAST...WHILE AN UPPER LEVEL LOW PRESSURE SYSTEM REMAINS
PARKED OFF THE NORTHERN CALIFORNIA COAST. THIS UPPER LOW AND ITS
ASSOCIATED SOUTHEASTERLY FLOW IS GUIDING AN INCREASING AMOUNT OF
MOISTURE AND INSTABILITY ALOFT INTO OREGON.

THE MOISTURE AND INSTABILITY WILL COMBINE WITH A SERIES OF
DISTURBANCES TO PRODUCE MULTIPLE ROUNDS OF THUNDERSTORMS ACROSS
WESTERN OREGON AND WASHINGTON. THE FIRST ROUND WAS LAST NIGHT...AND
RESULTED IN SEVERAL HUNDRED LIGHTNING STRIKES IN THE WILLAMETTE
NF...WITH OUTFLOW WINDS GUSTING NEAR 50 MPH IN EUGENE. THE NEXT
ROUND OF THUNDERSTORMS IS ALREADY BEGINNING TO DEVELOP ALONG THE
CASCADE CREST NEAR WILLAMETTE PASS. THESE WILL BECOME STRONGER AND
DEVELOP FURTHER NORTH ALONG THE CREST AS THE AFTERNOON PROGRESSES.
EVENTUALLY SOUTHEASTERLY FLOW WILL CARRY THESE STORMS INTO THE
WILLAMETTE VALLEY...AND POSSIBLY AS FAR WEST AS THE COAST THIS
EVENING. YET ANOTHER DISTURBANCE NEAR THE OREGON/CALIFORNIA/NEVADA
BORDER IS LINED UP TO PRODUCE EVEN MORE WIDESPREAD LIGHTNING TO THE
DISTRICT LATER TONIGHT INTO EARLY TUESDAY.

AS THE UPPER LEVEL LOW OFF THE CALIFORNIA COAST LIFTS NORTH INTO
OREGON TUESDAY...COMBINING WITH AN INCOMING PACIFIC COLD FRONT...EVEN
MORE THUNDERSTORMS ARE LIKELY. HOWEVER THESE WILL COME WITH AN
INCREASING AMOUNT OF MOISTURE...WITH CHANCES OF WETTING RAIN INCREASING
TUESDAY AND WEDNESDAY. TEMPERATURES WILL FALL BELOW NORMAL BY
WEDNESDAY WITH UNSETTLED WEATHER CONTINUING AS THE UPPER LOW LINGERS
NEARBY.  WEAGLE

.AVIATION...EXPECT VFR CONDITIONS TO REMAIN IN CONTROL THROUGH
THE REST OF THIS AFTERNOON INTO THIS EVENING. A WIND REVERSAL TO
SW HAS BEGUN TO OCCUR ON THE CENTRAL OREGON COAST...AND THIS
REVERSAL SHOULD SLOWLY WORK ITS WAY UP THE COAST TONIGHT. THIS
WILL LIKELY BRING IFR/MVFR STRATUS BACK INTO THE COAST FROM SOUTH
TO NORTH LATE IN THE EVENING AND OVERNIGHT. THE STRATUS MAY ALSO
TRY TO MAKE A PUSH INTO KEUG FOR A FEW HOURS TOMORROW MORNING. LOW
CLOUDS EXPECTED REMAIN ALONG THE COAST FOR QUITE A BIT OF THE DAY
BUT THE UPPER LEVEL MOISTURE AND POSSIBLE THUNDERSTORMS MIGHT MIX
OUT THE MARINE LAYER BRIEFLY.

THUNDERSTORMS ARE BEGINNING TO FORM OVER THE CENTRAL OREGON
CASCADES OVER THE PAST HOUR. EXPECT STORMS TO CONTINUE TO DEVELOP
AND BEGIN TO PUSH NORTHWARD INTO MUCH OF NORTHWEST OREGON AND
SOUTHWEST WASHINGTON. THUNDERSTORMS ARE EXPECTED TO INFLUENCE MUCH
OF THE REGION LATER THIS AFTERNOON INTO TONIGHT. ANOTHER UPPER
LEVEL DISTURBANCE WILL KEEP SHOWER AND THUNDERSTORM CHANCES
CONTINUING THROUGH TOMORROW. THERE IS A POTENTIAL FOR STRONG GUSTY
WINDS AND HAIL WITH SOME OF THE STRONGER STORMS.

KPDX AND APPROACHES...VFR CONDITIONS NEXT 24 HRS. BROKEN MID
LEVEL CLOUDS TO REMAIN THIS AFTERNOON. THEN THUNDERSTORMS LIKELY
TO MOVE INTO THE AREA BY LATE AFTERNOON OR EARLY EVENING. EXPECT
OCCASIONAL THUNDER AT THE TERMINAL AND ON THE APPROACHES...WITH
POSSIBLE GUSTY WINDS AND SMALL HAIL. SHOWER AND THUNDERSTORM
CHANCES CONTINUE THROUGH TOMORROW. PYLE

&&

.MARINE...CONDITIONS ARE FAIRLY BENIGN OVER THE WATERS THIS
AFTERNOON. WINDS HAVE DROPPED OFF TO AROUND 10 TO 15 KT...AND
SHOULD REMAIN BELOW 20 KT FOR THE NEXT FEW DAYS. A SOUTHERLY WIND
REVERSAL HAS BEGUN TO AFFECT THE CENTRAL OREGON NEAR SHORE
WATERS...AND EXPECT THIS REVERSAL TO PROGRESS UP THE COAST
TONIGHT. SEAS SIT IN THE 5 TO 7 FT RANGE WITH A W/NW SWELL WITH A
PERIOD AROUND 11 SEC NOW THE DOMINANT SWELL GROUP. AN UPPER LOW
WILL CONTINUE TO SPREAD HIGH BASED MOISTURE OVER THE WATERS MOVING
UP FROM THE SOUTH WITH THE POSSIBILITY OF A FEW THUNDERSTORMS
MOVING NORTH ACROSS THE WATERS TONIGHT AND EARLY TUE. THIS LOW
MOVES OUT OF THE AREA ONLY TO BE FOLLOWED BY ANOTHER UPPER LOW
APPROACHING THE WATERS LATE TUESDAY. THERE WILL BE A CONTINUING
CHANCE OF SHOWERS THROUGH MIDWEEK. EXPECT SEAS GENERALLY 5-6 FEET
THROUGH THE REST OF THE WEEK WITH WEST/NORTHWEST SWELL.

WE ARE CURRENTLY IN THE HIGH END OF THE TIDAL CURRENT CYCLE.
DECIDED TO ISSUE A SMALL CRAFT ADVISORY FOR ROUGH BAR CONDITIONS
FOR THE VERY STRONG EBB TOMORROW MORNING. CAUTION IS RECOMMENDED
ON THE BAR OVER THE NEXT FEW DAYS AND CROSSING DURING THE STRONG
EBBS SHOULD BE AVOIDED IF POSSIBLE. PYLE

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 11 AM PDT TUESDAY FOR ZONE 601-ZONE 602-
     ZONE 603-ZONE 604-ZONE 605-ZONE 606-ZONE 607-ZONE 608-ZONE
     612.

     HEAT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR CASCADE FOOTHILLS
     IN LANE COUNTY-CENTRAL COAST RANGE OF WESTERN OREGON-
     CENTRAL COLUMBIA RIVER GORGE-CENTRAL WILLAMETTE VALLEY-
     COAST RANGE OF NORTHWEST OREGON-GREATER PORTLAND METRO AREA-
     LOWER COLUMBIA-NORTHERN OREGON CASCADE FOOTHILLS-SOUTH
     WILLAMETTE VALLEY-UPPER HOOD RIVER VALLEY-WESTERN COLUMBIA
     RIVER GORGE.

WA...RED FLAG WARNING UNTIL 11 AM PDT TUESDAY FOR ZONE 601-ZONE 602-
     ZONE 604-ZONE 660.

     HEAT ADVISORY UNTIL 9 PM PDT THIS EVENING FOR CENTRAL COLUMBIA
     RIVER GORGE-GREATER VANCOUVER AREA-I-5 CORRIDOR IN COWLITZ
     COUNTY-SOUTH WASHINGTON CASCADE FOOTHILLS-WESTERN COLUMBIA
     RIVER GORGE-WILLAPA HILLS.

PZ...SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 5 AM TO
     8 AM PDT TUESDAY.

&&

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.