Fire Weather Outlook Discussion
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FNUS21 KWNS 201648
FWDDY1

DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1148 AM CDT WED AUG 20 2014

VALID 201700Z - 211200Z


...PORTIONS OF N-CNTRL ORE...EXTREME S-CNTRL WA...
THE ONGOING FORECAST FOR ELEVATED FIRE WEATHER CONDITIONS ACROSS
THIS REGION REMAINS VALID.  THE ONLY CHANGE WAS TO TRIM THE SRN
PORTION OF THE AREA TO PRIMARILY RETAIN THE LOWER ELEVATIONS...WHERE
THE LATEST MODEL GUIDANCE SUPPORTS THE HIGHEST PROBABILITY OF
SUSTAINED WLY AFTERNOON WIND SPEEDS APPROACHING 20 MPH.

...COASTAL RANGES OF SRN CA...
NUMEROUS CG LIGHTNING STRIKES HAVE OCCURRED OVER SRN CA THIS MORNING
EAST OF AN UPPER LOW IN A PERSISTENT SW/NE-ORIENTED BAND OF ELEVATED
THUNDERSTORMS.  GIVEN THE TRAINING NATURE OF THESE STORMS AND PW
VALUES AT OR NEAR 1.0 INCH...THESE STORMS ARE LIKELY PRODUCING
WETTING RAINS.  THE POTENTIAL FOR DRY THUNDERSTORMS SHOULD INCREASE
THIS AFTERNOON AS HEATING/DESTABILIZATION LEADS TO SURFACE-BASED
STORMS...ESPECIALLY ON THE NORTHWEST PERIPHERY OF THE CONVECTIVE
CLOUD BAND...WHERE PW VALUES ARE LOWER. THE OVERALL
CONFIDENCE/COVERAGE OF DRY THUNDERSTORMS...HOWEVER...IS TOO LOW TO
HIGHLIGHT AN AREA.

..JIRAK.. 08/20/2014

.PREV DISCUSSION... /ISSUED 0237 AM CDT WED AUG 20 2014/

...SYNOPSIS...
EARLY-MORNING MOISTURE-CHANNEL IMAGERY INDICATES THE CENTER OF A
WELL-DEFINED CYCLONE NEAR THE COAST OF SRN CA. THIS FEATURE IS
FORECAST TO MOVE LITTLE THROUGH THE PERIOD...WHILE A TROUGH TO ITS N
EXTENDS INTO THE NWRN CONUS. DOWNSTREAM...A RIDGE WILL BRANCH
NWWD/NWD FROM AN ANTICYCLONE OVER THE NRN GULF OF MEXICO AND SERN
STATES. ELSEWHERE...A MID-LEVEL TROUGH WILL SLOWLY DRIFT EWD ACROSS
PORTIONS OF THE GREAT LAKES REGION.

...PORTIONS OF N-CNTRL ORE...EXTREME S-CNTRL WA -- STRONG WIND/LOW
RH POTENTIAL...
A MODEST SFC PRESSURE GRADIENT WILL FAVOR WLY SFC WINDS AROUND 15-20
MPH IN A LOCALIZED AREA FROM THE LEE OF THE CASCADES AND THE
COLUMBIA GORGE TO PORTIONS OF THE COLUMBIA BASIN. RH VALUES ARE
FORECAST TO FALL TO 15-25 PERCENT IN COMBINATION WITH THESE WINDS
AMIDST DRY FUELS...SUPPORTING ELEVATED FIRE WEATHER CONDITIONS. THE
LACK OF AN EVEN TIGHTER SFC PRESSURE GRADIENT IS EXPECTED TO PREVENT
CRITICALLY STRONG WINDS FROM OCCURRING ON ANY MORE THAN A
BRIEF/SPOTTY BASIS.

...PORTIONS OF SRN WY -- STRONG WIND/LOW RH POTENTIAL...
WLY SFC WINDS AROUND 15 TO LOCALLY/OCCASIONALLY 20 MPH ARE EXPECTED
TO OCCUR TODAY. HOWEVER...THE LATEST MULTI-MODEL CONSENSUS SUGGESTS
THAT RH VALUES WILL ONLY FALL INTO THE MIDDLE 20S TO THE MIDDLE 30S
WITHOUT A WARMER/DRIER AIR MASS. WITHOUT LOWER RH...THE RISK FOR
ENHANCED FIRE WEATHER CONDITIONS WILL BE TOO LOW FOR FIRE-WEATHER
DELINEATIONS.

...COASTAL RANGES OF SRN CA -- DRY-THUNDERSTORM POTENTIAL...
ISOLATED THUNDERSTORMS WILL BE POSSIBLE...PARTICULARLY THIS
AFTERNOON AS TERRAIN CIRCULATIONS ARE DIURNALLY ENHANCED AMIDST
MARGINAL BUOYANCY. MODEST MID/HIGH-LEVEL FLOW WILL ENHANCE STORM
MOTIONS TO LIMIT PRECIPITATION AMOUNTS...AND SOME RISK FOR
LIGHTNING-INDUCED IGNITIONS WILL EXIST PROVIDED THE PRESENCE OF DRY
FUELS. THIS WOULD ESPECIALLY BE THE CASE ON THE EDGES OF RAIN CORES.
HOWEVER...GPS DATA...SURFACE OBSERVATIONS...AND FORECAST SOUNDINGS
ALL SUGGEST THAT SUFFICIENT TROPOSPHERIC MOISTURE WILL EXIST TO
SUPPORT WETTING RAINS WITH MANY STORMS -- E.G. THE PRESENCE OF
MODEST LOW-LEVEL MOISTURE AND PW VALUES OF 0.7 INCH TO LOCALLY OVER
1.0 INCH. THIS WILL IMPEDE THE OVERALL RISK FOR STRICTLY DRY
THUNDERSTORMS SUCH THAT FIRE-WEATHER HIGHLIGHTS HAVE NOT BEEN
INCLUDED AT THIS TIME.

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



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