Full Notification

URGENT - FIRE WEATHER MESSAGE
NATIONAL WEATHER SERVICE PORTLAND OR
216 PM PDT WED SEP 3 2014

...THERMAL TROUGH WEST OF THE CASCADES BRINGS CRITICAL BURNING CONDITIONS FOR NEW AND EXISTING FIRES...

.A THERMAL TROUGH WILL BUILD NORTH FROM CALIFORNIA BECOMING ENTRENCHED WEST OF THE CASCADES THURSDAY WITH EFFECTS LASTING THROUGH AT LEAST SATURDAY. THIS EVENT WILL ENCOMPASS VERY DRY HUMIDITY AND A COMBINATION OF CRITICAL WINDS AND UNSTABLE LOWER LEVELS. FOR THE RIDGES...WINDS WILL GENERALLY BE THE MAIN CONCERN DURING THE OVERNIGHT AND EARLY MORNING HOURS IN ADDITION TO NOTABLY UNSTABLE CONDITIONS DURING THE AFTERNOONS AND EVENINGS. FOR THE VALLEYS...WINDS WILL BE THE PRIMARY CONCERN DURING THE AFTERNOONS AND EVENINGS. PRIMARY CONCERN IS FOR AREAS MAINLY SOUTH OF THE COLUMBIA RIVER WHERE FUELS APPEAR TO BE MORE RECEPTIVE OF DRYING. CONDITIONS MAY IMPROVE SOME ON SUNDAY BUT MAY LAST UNTIL MONDAY AFTERNOON WHEN A STRONGER ONSHORE PUSH IS EXPECTED.


...RED FLAG WARNING IN EFFECT FROM NOON THURSDAY TO 11 PM PDT SATURDAY FOR WIND AND LOW RELATIVE HUMIDITY IN ADDITION TO CRITICALLY DRY AND UNSTABLE CONDITIONS ACROSS FIRE WEATHER ZONES ORZ601...ORZ602...ORZ603...ORZ604...ORZ605...ORZ606...ORZ607...ORZ608
AND ORZ612...

THE NATIONAL WEATHER SERVICE IN PORTLAND HAS ISSUED A RED FLAG WARNING FOR WIND AND LOW RELATIVE HUMIDITY...WHICH IS IN EFFECT FROM NOON THURSDAY TO 11 PM PDT SATURDAY.

* AFFECTED AREA...FIRE WEATHER ZONES
  ORZ601...ORZ602...ORZ603...ORZ604...ORZ605...ORZ606...ORZ607...ORZ608
  AND ORZ612.

* WINDS...RIDGE WINDS NORTHEAST TO EAST 15 TO 25 MPH WITH GUSTS UP TO 35 MPH. RIDGE WINDS STRONGEST OVERNIGHT AND EARLY MORNING HOURS. WILLAMETTE VALLEY WINDS NORTH TO NORTHEAST 15 TO 20 MPH WITH GUSTS TO AROUND 30 MPH MAINLY DURING THE AFTERNOON AND EVENING HOURS.

* RELATIVE HUMIDITY...RIDGES 15 TO 25 PERCENT WITH MODERATE TO POOR HUMIDITY RECOVERY OVERNIGHT. VALLEYS WILL SEE AFTERNOON HUMIDITY 10 TO 20 PERCENT.

* INSTABILITY...EXPECT MODERATE TO STRONG LOW LEVEL INSTABILITY WITH MIXING HEIGHTS AROUND 6000 FEET ABOVE MEAN SEA LEVEL ON THURSDAY INCREASING TO AROUND 8000 FEET ABOVE MEAN SEA LEVEL FRIDAY AND SATURDAY.

* IMPACTS...VERY LOW HUMIDITY COMBINED WITH WINDS WILL CREATE POTENTIAL FOR RAPID FIRE SPREAD ALONG THE GROUND. VERY LOW HUMIDITY COMBINED WITH UNSTABLE CONDITIONS WILL CREATE POTENTIAL FOR PLUME DOMINATED FIRE BEHAVIOR AND INCREASED SPOTTING   POTENTIAL.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A RED FLAG WARNING MEANS THAT CRITICAL FIRE WEATHER CONDITIONS ARE EITHER OCCURRING NOW...OR WILL SHORTLY. A COMBINATION OF STRONG WINDS...LOW RELATIVE HUMIDITY...AND WARM TEMPERATURES WILL CREATE EXPLOSIVE FIRE GROWTH POTENTIAL.