Storm Prediction Center Day 1 Fire Weather Outlook
Created: Wed Jun 19 16:34:03 UTC 2013
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ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 191633
DAY 1 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1133 AM CDT WED JUN 19 2013
VALID 191700Z - 201200Z
...CRITICAL FIRE WEATHER AREA FOR THE SERN HALF OF UT...PORTIONS OF
WRN/CNTRL/SRN CO...PORTIONS OF CNTRL/NRN/WRN NM...NRN/E-CNTRL
AZ...EXTREME SERN NV...
...CRITICAL FIRE WEATHER AREA FOR THE FOLLOWING LOCATIONS IN SRN
CA----MUCH OF THE ERN TWO-THIRDS OF SANTA BARBARA COUNTY...THE NRN
TWO-THIRDS OF VENTURA COUNTY...NWRN/N-CNTRL LOS ANGELES
COUNTY...PARTS OF FAR SRN KERN COUNTY...
...THE SERN HALF OF UT...PORTIONS OF WRN/CNTRL/SRN CO...PORTIONS OF
CNTRL/NRN/WRN NM...NRN/E-CNTRL AZ...EXTREME SERN NV...
ONLY MINOR ADJUSTMENTS WERE MADE TO THE CRITICAL AREA TO ACCOUNT FOR
LATEST MODEL TRENDS AND SURFACE OBSERVATIONS. PREVIOUS FORECAST
REASONING REMAINS ON TRACK. PLEASE SEE PREVIOUS OUTLOOK FOR FORECAST
DETAILS.
...THE FOLLOWING LOCATIONS IN SRN CA----MUCH OF THE ERN TWO-THIRDS
OF SANTA BARBARA COUNTY...THE NRN TWO-THIRDS OF VENTURA
COUNTY...NWRN/N-CNTRL LOS ANGELES COUNTY...PARTS OF FAR SRN KERN
COUNTY...
NO CHANGES. PLEASE SEE PREVIOUS OUTLOOK FOR DETAILS.
...SURROUNDING THE ERN CRITICAL AREA ACROSS PORTIONS OF
NV...CNTRL/SRN/WRN AZ...SWRN/S-CNTRL NM...CNTRL/N-CNTRL/ERN
CO...CNTRL/S-CNTRL WY...THE NWRN HALF OF UT...
NO CHANGES. PLEASE SEE PREVIOUS OUTLOOK FOR DETAILS.
..LEITMAN.. 06/19/2013
.PREV DISCUSSION... /ISSUED 0301 AM CDT WED JUN 19 2013/
...SYNOPSIS...
EARLY-MORNING WATER VAPOR IMAGERY INDICATES A STRONG MID-LEVEL
CYCLONE MOVING ASHORE OVER THE PACIFIC NW COAST. AN ACCOMPANYING
VIGOROUS SHORTWAVE TROUGH IS DIGGING SSEWD INTO NRN/CNTRL CA AND IS
BECOMING NEGATIVELY TILTED WITHIN THE SRN SEMICIRCLE OF THE BROADER
AREA OF CYCLONIC FLOW. THIS TROUGH WILL ADVANCE NEWD FROM PARTS OF
THE CNTRL GREAT BASIN TO THE NRN ROCKIES AND THE ADJACENT HIGH
PLAINS THROUGH TONIGHT...WHILE THE CENTER OF THE MID-LEVEL CYCLONE
SLOWLY PROGRESSES EWD FROM THE PACIFIC NW TO THE NRN ROCKIES. A ZONE
OF STRONG TROPOSPHERIC FLOW ATTENDANT TO THE SHORTWAVE TROUGH WILL
OVERLIE DRY/VERY DRY SFC CONDITIONS ACROSS PARTS OF THE CNTRL GREAT
BASIN...THE CNTRL/SRN ROCKIES...AND THE SW STATES TO ENHANCE THE
FIRE WEATHER THREAT. A SEPARATE AREA OF CRITICAL FIRE WEATHER
CONDITIONS IS FORECAST TO OCCUR ACROSS PORTIONS OF SRN CA.
...THE SERN HALF OF UT...PORTIONS OF WRN/CNTRL/SRN CO...PORTIONS OF
CNTRL/NRN/WRN NM...NRN/E-CNTRL AZ...EXTREME SERN NV...
---WINDS----
AS THE AFOREMENTIONED ZONE OF STRONG TROPOSPHERIC FLOW AFFECTS THE
REGION...SWLY SFC WINDS OF 20-25 MPH WITH HIGHER GUSTS ARE EXPECTED
IN TANDEM WITH DIURNALLY DEEPENING MIXED LAYERS THAT WILL ALLOW THE
STRONGER ALOFT TO BE MANIFESTED AT THE SFC. THE STRONG-WIND
POTENTIAL WILL BE AIDED BY A TIGHTENING SFC PRESSURE GRADIENT ACROSS
MANY LOCATIONS.
A RELATIVE WEAKNESS IN THE MAGNITUDE OF THE PRESSURE GRADIENT ACROSS
PARTS OF CNTRL/N-CNTRL NM MAY PREVENT SUSTAINED WIND SPEEDS FROM
BECOMING CRITICALLY STRONG THERE. HOWEVER...IN THIS AREA...FORECAST
SOUNDINGS INDICATE MIXED-LAYER HEIGHTS REACHING OVER 11
KFT...ALLOWING EVEN STRONGER MID-LEVEL FLOW -- I.E. AROUND THE
500-MB LEVEL -- TO BE MANIFESTED AT THE SFC AS FREQUENT GUSTS OF 25
TO 30 MPH. AND...WITH VERY LOW RH VALUES EXPECTED IN THIS AREA
AMIDST VERY DRY FUELS AND A WARM/HOT AIR MASS -- AS DISCUSSED
BELOW -- CRITICAL DESIGNATION IS WARRANTED DESPITE THE LOCALIZED
WEAKER SFC WINDS.
----RELATIVE HUMIDITY VALUES AND TEMPERATURES----
WITH AN ANTECEDENTLY DRY AIR MASS...AND DOWNSLOPE EFFECTS AIDING
BOUNDARY-LAYER WARMING/DRYING...RH VALUES ARE EXPECTED TO FALL TO
BETWEEN 4 AND 13 PERCENT DURING THE AFTERNOON ACROSS MOST LOCATIONS
WHILE VERTICAL MIXING STRENGTHENS. THIS WILL OCCUR AS TEMPERATURES
RISE INTO THE 80S AND 90S.
----FUELS----
FUELS ARE DRY TO VERY DRY ACROSS MUCH OF THE AREA WITH ONGOING
DROUGHT CONDITIONS IN PLACE...INCLUDING SEVERAL AREAS OF EXCEPTIONAL
DROUGHT CONDITIONS. THESE DRY/VERY FUELS WILL EXACERBATE THE FIRE
WEATHER THREAT. ACROSS PARTS OF THE CNTRL/SRN ROCKIES...SOME AREAS
HAVE RECEIVED WETTING RAINS ASSOCIATED WITH THUNDERSTORM ACTIVITY
RECENTLY. HOWEVER...MANY AREAS DID NOT RECEIVE APPRECIABLE
RAINFALL...YIELDING BELOW-NORMAL PRECIPITATION TO SUPPORT DRY FUELS.
...THE FOLLOWING LOCATIONS IN SRN CA----MUCH OF THE ERN TWO-THIRDS
OF SANTA BARBARA COUNTY...THE NRN TWO-THIRDS OF VENTURA
COUNTY...NWRN/N-CNTRL LOS ANGELES COUNTY...PARTS OF FAR SRN KERN
COUNTY...
----SYNOPTIC/MESOSCALE OVERVIEW----
THE LATEST OBSERVATIONAL DATA AND MODEL GUIDANCE OFFER LITTLE
OVERALL CHANGE REGARDING THE ANTICIPATED EVOLUTION OF THE PATTERN
SUPPORTING THIS CRITICAL FIRE WEATHER THREAT. UPSTREAM OF THE
SHORTWAVE TROUGH...SUBSIDENCE ALOFT WILL ALLOW FOR AN EWD MOTION OF
THE CENTER OF A SFC ANTICYCLONE COVERING PARTS OF THE PACIFIC HIGH
SEAS. THIS SUBSIDENCE WILL ALSO FOSTER ENEWD BRANCHING OF A RIDGE
AXIS FROM THE ANTICYCLONE CENTER INTO PARTS OF THE NWRN CONUS. AS A
N/S-ORIENTED LOW-LEVEL THERMAL RIDGE ALIGNING WITH THE LOWER CO
RIVER VALLEY STRENGTHENS...THE SFC PRESSURE GRADIENT WILL TIGHTEN
ACROSS THE CRITICAL AREA. THIS WILL ACCELERATE GENERALLY NLY FLOW
THROUGH THE SAN JOAQUIN VALLEY...WITH NWLY TO NELY WINDS
STRENGTHENING ACROSS THE COASTAL RANGES AND ADJACENT FOOTHILLS
THROUGH THE DAY. STRONG WINDS ARE EXPECTED TO CONTINUE THROUGH THE
OVERNIGHT HOURS TONIGHT. THIS WILL SUPPORT A STRENGTHENING OFFSHORE
FLOW COMPONENT ALONG PARTS OF THE SANTA BARBARA COUNTY AND THE FAR
WRN VENTURA COUNTY COASTLINES FOLLOWING THE DESCENT OF THIS FLOW IN
THE LEE OF THE SANTA YNEZ MOUNTAINS. DOWNSLOPE
EFFECTS/BOUNDARY-LAYER WARMING WILL AUGMENT SUBSIDENCE WITHIN THE
LARGE-SCALE SYNOPTIC FLOW REGIME TO SUPPORT A DRYING AIR MASS.
----WINDS----
THIS PATTERN WILL SUPPORT CRITICALLY STRONG NWLY TO NELY SFC WINDS
INCREASING TO 20-30 MPH WITH GUSTS REACHING 35-50 MPH THROUGH THE
DAY TODAY...WITH THESE WINDS CONTINUING INTO THE OVERNIGHT HOURS
TONIGHT. THE STRONGEST OF THESE WINDS WILL OCCUR ON A LOCALIZED
BASIS THROUGH FAVORED PASSES AND CANYONS. THE ANTICIPATION OF THESE
STRONG WINDS IS AFFIRMED BY THE LATEST 4-KM NAM GUIDANCE...ALONG
WITH OTHER HIGH-RESOLUTION MODEL GUIDANCE INCLUDING 4-KM AFWA
ENSEMBLE MODEL OUTPUT.
----RELATIVE HUMIDITY VALUES AND TEMPERATURES----
AFTER RH VALUES FALL INTO THE UPPER SINGLE DIGITS TO MIDDLE TEENS
DURING THE DAY TODAY...THE STRENGTHENING DOWNSLOPE FLOW COMPONENT
AND DECREASING PW WILL KEEP RH VALUES CRITICALLY LOW INTO THE
OVERNIGHT HOURS TONIGHT AS TEMPERATURES ONLY FALL INTO THE 60S AND
70S.
----FUELS----
FUELS ARE VERY DRY ACROSS THE AREA...WITH SEVERE DROUGHT CONDITIONS
IN PLACE AND BELOW-NORMAL PRECIPITATION DURING THE PAST FEW MONTHS.
GIVEN THE STATE OF THE FUELS...THE AFOREMENTIONED STRONG WINDS/LOW
RH WILL EXACERBATE THE FIRE WEATHER THREAT TO WARRANT CRITICAL FIRE
WEATHER DESIGNATION.
...SURROUNDING THE ERN CRITICAL AREA ACROSS PORTIONS OF
NV...CNTRL/SRN/WRN AZ...SWRN/S-CNTRL NM...CNTRL/N-CNTRL/ERN
CO...CNTRL/S-CNTRL WY...THE NWRN HALF OF UT...
MANY AREAS W OF A CNTRL/SRN-HIGH-PLAINS LEE TROUGH WILL EXPERIENCE
CRITICALLY LOW RH GIVEN A DRY AIR MASS AND DIURNALLY STRENGTHENING
VERTICAL MIXING. HOWEVER...IN THE ABSENCE OF STRONGER LOW/MID-LEVEL
FLOW IN MANY AREAS...CRITICALLY STRONG SUSTAINED WIND SPEEDS WILL BE
UNLIKELY IN COMBINATION WITH THESE LOW RH VALUES. AN EXCEPTION IS
ACROSS PORTIONS OF CNTRL/N-CNTRL CO...WHERE CRITICAL METEOROLOGICAL
CONDITIONS COULD ENSUE. HOWEVER...ACROSS THESE AREAS IN
CNTRL/N-CNTRL CO...MORE LIMITED FUEL DRYNESS MAY MITIGATE THE FIRE
WEATHER THREAT...AND RELATIVELY LOWER TEMPERATURES AND HIGHER RH MAY
ALSO MITIGATE THE FIRE WEATHER THREAT.
ALSO OF NOTE...THE AFOREMENTIONED CRITICAL METEOROLOGICAL CONDITIONS
ARE EXPECTED TO EXTEND INTO CNTRL/S-CNTRL WY. HOWEVER...COORDINATION
WITH THE RIVERTON WY AND CHEYENNE WY WEATHER FORECAST OFFICES
SUGGESTS THAT FUELS ARE NOT SUFFICIENTLY DRY ACROSS THESE AREAS TO
EXTEND THE CRITICAL NWD INTO PORTIONS OF CNTRL/S-CNTRL WY AT THIS
TIME.
...PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT...