Storm Prediction Center Day 1 Fire Weather Outlook

Created: Sun Jun 12 16:36:03 UTC 2011

Day 1 Fire Weather Forecast graphic

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   ZCZC SPCFWDDY1 ALL
   FNUS21 KWNS 121635
   
   DAY 1 FIRE WEATHER OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1135 AM CDT SUN JUN 12 2011
   
   VALID 121700Z - 131200Z
   
   ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF E-CNTRL/NERN AZ...MUCH
   OF CNTRL/NRN NM...S-CNTRL CO...FAR WRN SECTIONS OF THE TX/OK
   PANHANDLES...
   NO CHANGES TO PREVIOUS FORECAST REQUIRED.  WILL STILL REFRAIN FROM
   UPGRADING PORTIONS OF WRN OK AND WRN N TX TO A CRITICAL AREA AS
   FORECAST MODELS STILL DISAGREE ON THE AMOUNT OF DRYING THAT WILL
   OCCUR TODAY JUST AHEAD OF THE DRYLINE.  ADDITIONALLY...SOME
   LOCATIONS RECEIVED ANYWHERE FROM A HALF INCH TO OVER ONE INCH OF
   RAINFALL SATURDAY NIGHT WHICH WOULD FURTHER MITIGATE THE OVERALL
   THREAT EVEN IF RH VALUES DO FALL TO NEAR OR JUST BELOW 20 PERCENT.
   
   ..LEITMAN.. 06/12/2011
   
   .PREV DISCUSSION... /ISSUED 0342 AM CDT SUN JUN 12 2011/
   
   ...SYNOPSIS...
   LATEST WATER VAPOR IMAGERY DEPICTS A MID-LEVEL TROUGH POSITIONED
   ACROSS PORTIONS OF THE WRN CONUS...WITH A MID-LEVEL RIDGE PERSISTING
   OVER PORTIONS OF THE SRN PLAINS. THE RIDGE IS FORECAST TO GRADUALLY
   BUILD/AMPLIFY TODAY...WHILE A WELL-DEFINED...MID-LEVEL IMPULSE
   /CURRENTLY OVER SWRN AZ/ TRANSLATES NEWD TOWARD THE FOUR CORNERS
   REGION. THIS PATTERN WILL SUPPORT A ZONE OF ENHANCED MID-LEVEL SWLY
   TO WSWLY FLOW OVER PORTIONS OF THE SOUTHWEST DESERTS...CNTRL GREAT
   BASIN...SRN/CNTRL ROCKIES...AND SRN/CNTRL HIGH PLAINS...WITH 700-MB
   SPEEDS REACHING 30 MPH AND 500-MB SPEEDS REACHING 45 MPH /SOMEWHAT
   STRONGER COMPARED TO THOSE ON SATURDAY/. ACROSS MUCH OF THIS
   REGION...SATURDAY EVENING OBSERVED SOUNDINGS DEPICT AN ENVIRONMENT
   CHARACTERIZED BY STEEP LOW-TO-MID-LEVEL LAPSE RATES WITH DRY
   BOUNDARY LAYER CONDITIONS ALREADY IN PLACE. THESE FACTORS WILL
   SUPPORT A BROAD AREA OF ELEVATED FIRE WEATHER CONDITIONS...WITH AN
   EMBEDDED AREA OF CRITICAL CONDITIONS ACROSS PORTIONS OF E-CNTRL/NERN
   AZ...MUCH OF CNTRL/NRN NM...S-CNTRL CO...AND FAR WRN SECTIONS OF THE
   TX/OK PANHANDLES. MEANWHILE...A DRYLINE WILL EXTEND ACROSS PARTS OF
   FAR WRN TX TO THE SOUTH OF A DEEPENING SFC LOW AND ASSOCIATED
   FRONTAL ZONE DRAPED ACROSS PORTIONS OF THE CNTRL/SRN PLAINS.
   
   ...PORTIONS OF E-CNTRL/NERN AZ...MUCH OF CNTRL/NRN NM...S-CNTRL
   CO...FAR WRN SECTIONS OF THE TX/OK PANHANDLES...
   SWLY WINDS OF 20 TO 25 MPH ARE FORECAST TO ALIGN WITH RH VALUES FROM
   THE MIDDLE SINGLE DIGITS TO THE MIDDLE TEENS...AS TEMPERATURES WARM
   INTO THE MIDDLE 80S TO MIDDLE 90S. VERY STEEP LOW/MID-LEVEL LAPSE
   RATES WILL BE ASSOCIATED WITH STRONG VERTICAL MIXING...WITH
   MIXED-LAYER HEIGHTS FORECAST TO INCREASE TO AOA 14 KFT AGL IN MANY
   AREAS. THIS WILL ALLOW FOR THE STRONGER MID-LEVEL FLOW TO BE
   MANIFESTED AT THE SURFACE...WITH GUSTS REACHING 30 TO 40 MPH. THESE
   WINDS ARE FORECAST TO BE SOMEWHAT STRONGER COMPARED TO THOSE ON
   SATURDAY IN RESPONSE TO THE STRENGTHENING MID-LEVEL FLOW. ALSO...THE
   DOWNSLOPE COMPONENT OF THE FLOW INTO THE SAN LUIS VALLEY AND OVER
   THE ERN SLOPES OF THE SANGRE DE CRISTO AND SACRAMENTO MOUNTAINS WILL
   FURTHER CONTRIBUTE TO THE STRONG WINDS AND LOW RH VALUES OVER ERN
   PORTIONS OF THE CRITICAL AREA. GIVEN THESE FACTORS AND THE ONGOING
   DROUGHT...CRITICAL CONDITIONS ARE ANTICIPATED.
   
   ...PORTIONS OF WRN OK...WRN TX...SERN NM...
   TO THE EAST OF THE CRITICAL AREA...A COUPLE OF REGIONS OF ELEVATED
   FIRE WEATHER CONDITIONS ARE ANTICIPATED:
   
   1. NEAR AND EAST OF THE DRYLINE ACROSS PORTIONS OF WRN OK AND WRN
   TX...THE RELATIVELY TIGHT SFC PRESSURE GRADIENT BETWEEN THE
   AFOREMENTIONED LOW AND A RIDGE AXIS CENTERED OVER THE NRN GULF OF
   MEXICO SHOULD SUPPORT SSELY TO SLY WINDS OF 15 TO 20 MPH...WHERE RH
   VALUES ARE FORECAST TO FALL INTO THE LOWER TO MIDDLE 20S. THE
   STRONGEST OF THESE WINDS ARE EXPECTED ACROSS PORTIONS OF WRN OK AND
   WRN NORTH TX...WHERE SOME MODEL GUIDANCE SUGGESTS THE POTENTIAL FOR
   EVEN STRONGER WINDS TO OCCUR. HOWEVER...MODEL-TO-MODEL VARIATIONS
   STILL EXIST WITH REGARD TO THE STRENGTH OF THE PRESSURE GRADIENT AND
   ASSOCIATED WIND SPEEDS. ALSO...MODEL VARIABILITY EXISTS WITH REGARD
   TO HOW MUCH RH VALUES WILL FALL NEAR AND EAST OF THE DRYLINE -- E.G.
   THE GFS MODEL IS RELATIVELY LESS AGGRESSIVE WITH DROPPING RH VALUES
   AND CASTS DOUBT ON ANY CRITICALLY LOW RH VALUES OCCURRING FOR LONGER
   THAN A BRIEF DURATION. GIVEN THESE REMAINING UNCERTAINTIES...AND THE
   ANTICIPATED ABSENCE OF A GREATER WLY COMPONENT OF NEAR-SFC FLOW --
   I.E. ONE THAT WOULD ADVECT AN EVEN DRIER/HOTTER AIR MASS /SUBJECTED
   TO DOWNSLOPE EFFECTS/ FARTHER EAST TOWARD THE TIGHTER SFC PRESSURE
   GRADIENT -- AN UPGRADE TO CRITICAL DELINEATION IS NOT BEING MADE AT
   THE MOMENT. ADDITIONALLY...THE FIRE WEATHER THREAT ACROSS PORTIONS
   OF NWRN OK COULD BE MITIGATED BY THE RECENT OCCURRENCE OF
   PRECIPITATION SATURDAY EVENING/NIGHT.
   
   2. FOR LOCATIONS WEST OF THE DRYLINE ACROSS SERN NM AND PORTIONS OF
   FAR WRN TX...SSWLY TO SWLY WINDS AROUND 15 MPH ARE FORECAST TO ALIGN
   WITH RH VALUES FROM THE MIDDLE SINGLE DIGITS TO THE MIDDLE TEENS.
   HOWEVER...WITH THE AXIS OF STRONGER MID-LEVEL FLOW FORECAST TO
   REMAIN FARTHER TO THE WEST...AND IN THE ABSENCE OF A TIGHTER SFC
   PRESSURE GRADIENT...THE DURATION OF ANY CRITICALLY STRONG WINDS IS
   EXPECTED TO BE SUFFICIENTLY BRIEF SUCH THAT CRITICAL DELINEATION IS
   NOT WARRANTED.
   
   ALSO...AN ISOLATED THUNDERSTORM COULD DEVELOP OVER FAR WRN TX DUE TO
   CONVERGENCE ALONG THE DRYLINE. A DRY THUNDERSTORM MODE COULD
   OCCUR...AS NAM/GFS FORECAST SOUNDINGS INDICATE A DEEP...WELL-MIXED
   SUB-CLOUD LAYER...DRY SFC CONDITIONS...MODEST WLY MID/UPPER-LEVEL
   FLOW...AND PWAT VALUES OF 0.55 TO 0.70 INCH. HOWEVER...WITHOUT ANY
   APPRECIABLE MID/UPPER-LEVEL ASCENT...THE COVERAGE OF ANY STORMS
   WOULD BE VERY SPARSE...WHICH WILL SUBSTANTIALLY MITIGATE THE OVERALL
   THREAT FOR LIGHTNING-INDUCED IGNITIONS.
   
   ...FAR SERN CA...SRN NV...PORTIONS OF NRN/WRN/SRN AZ...SRN
   UT...SWRN/FAR NWRN NM...SWRN CO...
   FOR THE REGION SURROUNDING THE WRN SECTIONS OF THE CRITICAL
   AREA...SLY TO SWLY WINDS OF 15 TO 20 MPH WITH HIGHER GUSTS ARE
   FORECAST TO COMBINE WITH RH VALUES FROM THE MIDDLE SINGLE DIGITS TO
   THE MIDDLE TEENS TO RESULT IN ELEVATED FIRE WEATHER CONDITIONS. THE
   STRONGEST OF THESE WINDS ARE EXPECTED TO OCCUR ACROSS PORTIONS OF
   SWRN NM AND FAR SERN AZ...WHERE SOME MODEL GUIDANCE SUGGESTS AN AXIS
   OF ENHANCED MID-LEVEL FLOW COULD BE PRESENT. HOWEVER...THE SFC
   PRESSURE GRADIENT AND OVERALL MID-LEVEL FLOW STRENGTH ARE FORECAST
   TO BE RELATIVELY WEAKER ACROSS THIS REGION COMPARED TO THE CRITICAL
   AREA. ACCORDINGLY...THE COVERAGE AND DURATION OF ANY CRITICALLY
   STRONG SUSTAINED WINDS IS EXPECTED TO BE TOO SPOTTY AND
   BRIEF...RESPECTIVELY...TO WARRANT CRITICAL DELINEATION.
   
   ...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...
   
      

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