773
FNUS21 KWNS 171646
FWDDY1
DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1146 AM CDT MON JUN 17 2013
VALID 171700Z - 181200Z
...WRN TWO-THIRDS OF NM...WRN TWO-THIRDS OF CO -- DRY THUNDERSTORM
POTENTIAL...
RECENT WATER VAPOR IMAGERY INDICATES A MID-LEVEL SHORTWAVE IMPULSE
CROSSING PARTS OF THE SRN ROCKIES. THE ASCENT PLUME PRECEDING THIS
FEATURE WAS RESPONSIBLE FOR ISOLATED THUNDERSTORM ACTIVITY ACROSS
PARTS OF CNTRL/WRN NM EARLIER THIS MORNING. WEAKLY SUBSIDENT FLOW IN
THE WAKE OF THIS IMPULSE MAY OVERLIE THE WRN TWO-THIRDS OF NM THIS
AFTERNOON...WHILE NEUTRAL MID-LEVEL HEIGHT TENDENCIES -- I.E.
LACKING DEEP-LAYER FORCING FOR LARGE-SCALE VERTICAL MOTION -- EXIST
OVER THE WRN TWO-THIRDS OF CO.
FOR THIS AFTERNOON...THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER THE
HIGHER TERRAIN AS MODESTLY ENHANCED MID-LEVEL MOISTURE OVER THE WRN
FRINGES OF A S-CNTRL/SERN-CONUS PLUME OF RICHER DEEP MOISTURE
OVERLIES STRENGTHENING OROGRAPHIC CIRCULATIONS AMIDST MARGINAL
INSTABILITY. THE PRESENCE OF PW VALUES FROM 0.5 TO 0.9 INCH IN MANY
LOCATIONS PER GPS DATA...AND DIURNALLY DEEPENING INVERTED-VEE
PROFILES ENHANCING SUB-CLOUD EVAPORATION...SUGGEST THAT
THUNDERSTORMS WILL PRODUCE LIMITED PRECIPITATION.
HOWEVER...AS INDICATED IN THE PREVIOUS FORECAST...LACKING DEEP-LAYER
FORCING FOR ASCENT IN AREAS WHERE RELATIVELY LOWER PW WOULD FOSTER A
DRY-THUNDERSTORM MODE WILL LARGELY SUPPRESS THE COVERAGE OF DRY
THUNDERSTORMS -- I.E. ACROSS WRN NM AND WRN CO. AS
SUCH...DRY-THUNDERSTORM CRITICAL DESIGNATION IS NOT WARRANTED.
ELSEWHERE...HIGHER THUNDERSTORM COVERAGE MAY OCCUR IN AREAS WHERE PW
VALUES ARE AT THE HIGHER END OF THE AFOREMENTIONED
RANGE...SUPPORTING A MIXED WET/DRY THUNDERSTORM MODE.
REGARDLESS...LIGHTNING-INDUCED IGNITIONS MAY BE OF
CONCERN...ESPECIALLY OVER THE OUTER PERIPHERIES OF RAIN CORES AMIDST
DRY/VERY DRY FUELS. STRONG OUTFLOW WINDS FROM THE STORMS COULD
ENHANCE THE SPREAD OF FIRES.
...PORTIONS OF WRN NM...CNTRL/SRN UT...AZ...NV...AND ADJACENT PARTS
OF FAR ERN CA...
NO CHANGES HAVE BEEN MADE TO THE ONGOING FORECAST. THE LATEST
CONSENSUS AMONGST SHORT-RANGE MODEL SOLUTIONS SUGGESTS THAT
CRITICALLY STRONG SUSTAINED WIND SPEEDS ARE NOT EXPECTED TO OCCUR IN
ASSOCIATION WITH CRITICALLY LOW RH IN THE ABSENCE OF STRONGER
LOW/MID-LEVEL FLOW.
..COHEN.. 06/17/2013
.PREV DISCUSSION... /ISSUED 0339 AM CDT MON JUN 17 2013/
...SYNOPSIS...
IN THE MID LEVELS...BROADLY CYCLONIC FLOW WILL COVER PARTS OF THE
NERN CONUS AND GREAT LAKES...WHILE A RIDGE UPSTREAM OVER THE ROCKIES
SLOWLY PROGRESSES EWD AND REACHES THE ADJACENT HIGH PLAINS BY LATE
IN THE PERIOD. A MID-LEVEL CYCLONE -- CURRENTLY SPINNING OVER THE
ERN PACIFIC WATERS OFF THE COAST OF WA/ORE AND BRITISH COLUMBIA PER
EARLY-MORNING WATER VAPOR IMAGERY -- WILL EDGE EWD TOWARD THE
COASTLINE. HOWEVER...THE CENTER OF THE CYCLONE IS CURRENTLY EXPECTED
TO REMAIN OFFSHORE THROUGH THE PERIOD. A BAND OF ENHANCED MID-LEVEL
FLOW ASSOCIATED WITH THE RELATIVELY TIGHTER HEIGHT GRADIENT BETWEEN
THE CYCLONE CENTER AND THE DOWNSTREAM RIDGE WILL BEGIN TO EXTEND
ACROSS PORTIONS OF THE WRN CONUS.
...WRN TWO-THIRDS OF NM...WRN TWO-THIRDS OF CO -- DRY THUNDERSTORM
POTENTIAL...
THE COMBINATION OF DIURNALLY ENHANCED BUOYANCY AND OROGRAPHIC
CIRCULATIONS WILL FOSTER THE DEVELOPMENT OF THUNDERSTORMS DURING THE
AFTERNOON AMIDST MODEST QUANTITIES OF MID-LEVEL MOISTURE.
PRECIPITATION AMOUNTS WILL BE LIMITED GIVEN PW VALUES BETWEEN 0.5
AND 0.9 INCH AND SUB-CLOUD EVAPORATION WITHIN DEEP SFC-BASED MIXED
LAYERS.
THE LIMITED DEGREE OF DEEP-LAYER FORCING FOR ASCENT IS EXPECTED TO
SUPPRESS THUNDERSTORM COVERAGE IN AREAS WHERE RELATIVELY LOWER PW
WOULD FOSTER A DRY-THUNDERSTORM MODE...SUCH THAT A DRY-THUNDERSTORM
CRITICAL AREA IS NOT WARRANTED -- I.E. ACROSS WRN NM AND WRN CO.
ELSEWHERE...HIGHER THUNDERSTORM COVERAGE WILL BE POSSIBLE IN AREAS
WHERE PW VALUES ARE AT THE HIGHER END OF THE AFOREMENTIONED
RANGE...SUPPORTING A MIXED WET/DRY THUNDERSTORM MODE.
REGARDLESS...IGNITIONS RESULTING FROM LIGHTNING STRIKES WILL BE OF
CONCERN...PARTICULARLY OVER THE OUTER PERIPHERIES OF RAIN CORES
AMIDST DRY/VERY DRY FUELS. STRONG OUTFLOW WINDS FROM THE STORMS
COULD ENHANCE THE SPREAD OF FIRES.
...PORTIONS OF WRN NM...CNTRL/SRN UT...AZ...NV...AND ADJACENT PARTS
OF FAR ERN CA...
ACROSS MUCH OF THE AREA...RH VALUES ARE EXPECTED TO FALL TO THE
MIDDLE SINGLE DIGITS TO THE MIDDLE TEENS DURING THE AFTERNOON OWING
TO STRONG DIURNAL HEATING AMIDST A DRY AIR MASS. COMBINING WITH
THESE RH VALUES...SSWLY TO WLY SFC WINDS OF 10 TO AROUND 15 MPH ARE
EXPECTED DURING THE AFTERNOON...WHICH MAY SUPPORT MODESTLY ELEVATED
FIRE WEATHER CONDITIONS. HOWEVER...IN AREAS WHERE RH VALUES BECOME
CRITICALLY LOW...WEAK LOW/MID-LEVEL FLOW IS EXPECTED TO PREVENT SFC
WIND SPEEDS FROM BECOMING CRITICALLY STRONG.
THE AFOREMENTIONED BAND OF ENHANCED MID-LEVEL FLOW COULD SUPPORT
SLIGHTLY STRONGER SFC WINDS -- I.E. SUSTAINED WIND SPEEDS OF 15 TO
AROUND 20 MPH AND HIGHER GUSTS -- ACROSS THE HIGHER ELEVATIONS IN
FAR NWRN NV AND ADJACENT FAR ERN CA. HOWEVER...RELATIVELY COOLER
CONDITIONS IN THESE AREAS SHOULD AID IN LIMITING THE POTENTIAL FOR
CRITICALLY LOW RH.
GIVEN THE ANTICIPATED LACK OF OVERLAP OF CRITICALLY STRONG SUSTAINED
WIND SPEEDS WITH CRITICALLY LOW RH...FIRE WEATHER HIGHLIGHTS HAVE
NOT BEEN INCLUDED.
...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...
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