Fire Weather Outlook Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
000
FNUS21 KWNS 291655
FWDDY1

DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1155 AM CDT SAT AUG 29 2015

VALID 291700Z - 301200Z

...CRITICAL FIRE WEATHER AREA FOR ERN WA...NERN ORE...AND THE ID
PANHANDLE...

NO CHANGES HAVE BEEN MADE TO THE ONGOING FORECAST. THE LATEST
SHORT-RANGE MODEL GUIDANCE AND OBSERVATIONAL DATA SUGGEST THAT
ADDITIONAL CRITICAL AREAS AND/OR EXPANSION OF THE ONGOING CRITICAL
AREA ARE NOT NECESSARY WITHOUT HIGHER CONFIDENCE IN A BROADER AREA
OF ANY MORE THAN BRIEF/SPOTTY CRITICAL CONDITIONS.

..COHEN.. 08/29/2015

.PREV DISCUSSION... /ISSUED 0332 AM CDT SAT AUG 29 2015/

...SYNOPSIS...
AN UPPER TROUGH EVIDENT ON IR/WV SATELLITE IMAGERY EARLY THIS
MORNING APPROACHING THE WA/ORE COAST WILL MOVE NEWD OVER THE PACIFIC
NORTHWEST AND BRITISH COLUMBIA TODAY AND TONIGHT. STRONG MID-LEVEL
FLOW ASSOCIATED WITH THIS FEATURE COMBINED WITH A SFC COLD FRONTAL
PASSAGE WILL LIKELY RESULT IN ELEVATED TO CRITICAL FIRE WEATHER
CONDITIONS ACROSS A LARGE PORTION OF THE INTERIOR PACIFIC
NORTHWEST...GREAT BASIN...NRN/CNTRL ROCKIES...AND NRN/CNTRL HIGH
PLAINS THIS AFTERNOON AND EVENING.

...MUCH OF THE INTERIOR PACIFIC NORTHWEST...GREAT BASIN...NRN/CNTRL
ROCKIES...AND NRN/CNTRL HIGH PLAINS...
AS STRONG MID-LEVEL FLOW OF 50-80 KT ASSOCIATED WITH THE UPPER
TROUGH MOVES OVER THE PACIFIC NORTHWEST...A SFC COLD FRONT WILL ALSO
MOVE EWD OVER THIS AREA. LOW-LEVEL WINDS SHOULD SHIFT FROM SLY IN
THE MORNING TO SWLY/WLY BY THE AFTERNOON AND EVENING BEHIND THE
FRONT. SUSTAINED WIND SPEEDS IN THE LEE OF THE CASCADES WILL LIKELY
INCREASE TO 20-35 MPH...WITH HIGHER GUSTS OF 50 TO 60 MPH
POSSIBLE...ESPECIALLY IN HIGHER TERRAIN. RH VALUES SHOULD DECREASE
ONLY MARGINALLY WITH FRONTAL PASSAGE ACROSS THE INTERIOR PACIFIC
NORTHWEST...GENERALLY INTO THE 20-25 PERCENT RANGE FOR A FEW HOURS
PER LATEST RAP FORECAST SOUNDINGS. THE CRITICAL AREA HAS BEEN
EXPANDED SLIGHTLY SWD TO ENCOMPASS POTIONS OF NERN ORE GIVEN LATEST
SHORT-TERM MODEL GUIDANCE. THE EXPECTED STRENGTH OF THE WINDS
COMBINED WITH ONGOING FIRES IN THIS REGION SUPPORTS THE CRITICAL
AREA FOR PORTIONS OF ERN WA...NERN ORE...AND THE ID PANHANDLE...EVEN
THOUGH CRITICAL RH THRESHOLDS MAY NOT BE STRICTLY MET.

A LARGER ELEVATED AREA HAS BEEN MAINTAINED WITH MINOR EXPANSIONS FOR
THE REMAINDER OF THE INTERIOR PACIFIC NORTHWEST AND PORTIONS OF THE
GREAT BASIN...NRN/CNTRL ROCKIES...AND NRN/CNTRL HIGH PLAINS...WHERE
STRONG/GUSTY WINDS AND RH VALUES APPROACHING CRITICAL LEVELS WILL
INCREASE FIRE WEATHER CONCERNS. ACROSS THESE REGIONS...FORECAST WIND
SPEEDS AND/OR RH VALUES DO NOT CURRENTLY EXCEED CRITICAL THRESHOLDS
ON A WIDESPREAD BASIS...ALTHOUGH LOCALLY CRITICAL FIRE WEATHER
CONDITIONS MAY OCCUR THIS AFTERNOON...PARTICULARLY ACROSS THE NRN
ROCKIES WHERE FORECAST LOW-LEVEL WINDS ARE A BIT STRONGER. IF FUTURE
SHORT-TERM GUIDANCE INDICATES RH VALUES FALLING BELOW 20 PERCENT
ACROSS PORTIONS OF N-CNTRL MT FOR A FEW HOURS THIS AFTERNOON...THEN
A CRITICAL DESIGNATION MAY BE NEEDED.

THE ISOLATED DRY THUNDERSTORM AREA CONTAINED WITHIN THE ELEVATED
AREA HAS BEEN ADJUSTED FOR LATEST CONVECTION ALLOWING MODEL GUIDANCE
AND 00Z REGIONAL SOUNDINGS. ACROSS THIS AREA...LARGE-SCALE ASCENT
ASSOCIATED WITH THE APPROACHING UPPER TROUGH AND TOPOGRAPHIC
INFLUENCES SHOULD ENCOURAGE THE FORMATION OF ISOLATED TO WIDELY
SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING. SOME OF THESE
THUNDERSTORMS MAY BE DRY...WITH PWAT VALUES FORECAST TO BE MAINLY IN
THE 0.75-1.00 INCH RANGE. THESE FORECAST VALUES MATCH FAIRLY WELL
WITH LATEST GPS TPW SATELLITE ESTIMATES. FAST STORM MOTIONS AND DRY
SUB-CLOUD LAYERS SHOULD GENERALLY LIMIT WETTING RAINFALL AMOUNTS...
AND ANY LIGHTNING STRIKES COULD ENCOURAGE NEW FIRE STARTS IN THE
PRESENCE OF DRY FUELS.

...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.