Fire Weather Outlook Discussion
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FNUS28 KWNS 022045
FWDD38

DAY 3-8 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0345 PM CDT THU JUL 02 2015

VALID 041200Z - 101200Z

THE EXTENDED PERIOD WILL BEGIN WITH BROAD CYCLONIC FLOW ALOFT ACROSS
THE ERN TWO-THIRDS OF THE CONUS...WHILE RIDGING IS MAINTAINED OVER
MUCH OF THE INTER-MOUNTAIN WEST. AS SEVERAL SHORTWAVE TROUGHS
EMBEDDED IN W/NWLY FLOW ALOFT TRANSLATE ACROSS THE PAC NW TOWARDS
THE NRN PLAINS...THE WRN RIDGE WILL DE-AMPLIFY SLIGHTLY...AND A
REX-BLOCK PATTERN IS EXPECTED TO DEVELOP OFFSHORE OF THE WEST COAST
BY EARLY NEXT WEEK. FORECAST UNCERTAINTY INCREASES THROUGH MID
WEEK...AS GLOBAL GUIDANCE DIVERGES REGARDING THE SPEED OF THE EWD
PROGRESSION OF THE MID/UPPER-LEVEL LOW WEST OF CA.

...D3/SAT -- PORTIONS OF THE PAC NW...
THE PREVIOUS 40-PERCENT DELINEATION WAS MAINTAINED...WITH SOME
SLIGHT EXPANSION TO ACCOUNT FOR INCREASING CONFIDENCE IN GUSTY NLY
WINDS FOLLOWING THE PASSAGE OF A COLD FRONT ACROSS THE COLUMBIA
BASIN...OKANOGAN VALLEY...AND VICINITY. WITH TEMPERATURES REMAINING
WELL ABOVE NORMAL...DEEP MIXING WILL ENCOURAGE RH VALUES FALLING TO
AROUND 10-20 PERCENT BY LATE IN THE DAY. AS FUELS REMAIN QUITE
DRY...AT LEAST AN ELEVATED FIRE-WX THREAT IS EXPECTED ACROSS
PORTIONS OF CNTRL/ERN WA AND FAR NRN ORE. FARTHER EAST...THE PASSAGE
OF A SHORTWAVE TROUGH WILL ENHANCE WLY FLOW ALOFT...SUPPORTING
BREEZY CONDITIONS ACROSS PORTIONS OF WRN MT. HOT/DRY CONDITIONS WILL
ALSO PERSIST...SUPPORTING SOME ENHANCEMENT OF THE FIRE-WX THREAT
HERE AS WELL. HOWEVER...DUE TO SOME UNCERTAINTY IN THE FORECAST WIND
STRENGTH...THE 40-PERCENT DELINEATION HAS NOT BEEN EXPANDED EWD WITH
THIS FORECAST.

...D3/SAT-D7/WED -- NRN SIERRA...SRN CASCADES...CNTRL/ERN ORE...AND
SRN ID...
THROUGH THE WEEKEND AND INTO NEXT WEEK...CHANCES FOR TSTMS WILL
SLOWLY SPREAD N/EWD FROM PORTIONS OF THE NRN SIERRA/WRN GREAT BASIN
INTO SRN/ERN ORE AND SRN ID. AS WEAK PERTURBATIONS GRADUALLY
PROGRESS AROUND THE PERIPHERY OF ANTICYLONIC FLOW CENTERED TO THE
SE...DIURNAL HEATING/OROGRAPHIC CIRCULATIONS WILL YIELD TSTM
DEVELOPMENT EACH DAY. THE GREATEST CONFIDENCE IN DRY-TSTM FORMATION
EXISTS D4/SUN-D6/TUE OVER PORTIONS OF SRN/ERN ORE...WHERE FCST PWAT
VALUES OF 0.75-0.9 IN/MODEST STORM MOTIONS/DEEP DRY SUB-CLOUD LAYERS
SHOULD BE PRESENT. AS SUCH...10-PERCENT DELINEATIONS WERE INTRODUCED
FOR THIS AREA DURING THE D4-D6 PERIOD. FARTHER SOUTH/EARLIER IN THE
PERIOD...HIGHER PWATS SHOULD PRECLUDE A GREATER THREAT...ALTHOUGH A
FEW IGNITIONS MAY STILL BE POSSIBLE AWAY FROM THE MAIN PCPN CORES.
BY D6/TUE-D7/WED...THE THREAT FOR DRY TSTMS MAY SHIFT INTO ERN
ORE/SRN ID...BUT LOWER FCST CONFIDENCE PRECLUDES DELINEATIONS AT
THIS TIME.

...D7/WED-D8/THU -- SRN GREAT BASIN...
INCREASING SWLY FLOW ALOFT AHEAD OF A MID/UPPER-LEVEL LOW MAY FAVOR
BREEZY/DRY CONDITIONS AND SOME INCREASE IN THE FIRE-WX THREAT OVER
PORTIONS OF THE SRN GREAT BASIN LATE IN THE EXTENDED PERIOD.
HOWEVER...DUE TO UNCERTAINTY IN THE EVOLUTION OF THE LOW ALOFT WEST
OF CA...AND THE RESULTANT STRENGTH OF THE SWLY FLOW...NO
DELINEATIONS WILL BE INTRODUCED AT THIS TIME.

..PICCA.. 07/02/2015

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




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