Fire Weather Outlook Discussion
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FNUS22 KWNS 251552
FWDDY2

DAY 2 FIRE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1051 AM CDT SAT APR 25 2015

VALID 261200Z - 271200Z

CHANGES WERE MADE TO THE ELEVATED AREA ACROSS SE NM AND W TX BASED
ON LATEST MODEL TRENDS AND FUELS FORECAST DATA. OTHERWISE THE
PREVIOUS FORECAST IS ON TRACK. SEE DISCUSSION BELOW FOR MORE
DETAILS.

..LEITMAN.. 04/25/2015

.PREV DISCUSSION... /ISSUED 0321 AM CDT SAT APR 25 2015/

...SYNOPSIS...
A HIGH-AMPLITUDE MID-LEVEL TROUGH EXTENDING FROM THE GREAT BASIN TO
THE DESERT SW EARLY IN THE PERIOD WILL TRACK EWD. THIS TROUGH IS
FORECAST TO DEVOLVE INTO TWO SEPARATE PERTURBATIONS ADVANCING
THROUGH RESPECTIVE NRN/SRN STREAMS. BOTH OF THESE PERTURBATIONS WILL
MOVE IN PHASE TOWARD THE HIGH PLAINS. A BELT OF ENHANCED MID-LEVEL
FLOW ON THE SRN PERIPHERY OF THE SRN PERTURBATION WILL EMERGE OVER
PARTS OF THE SRN HIGH PLAINS WHERE IT WILL ENCOURAGE LEE
CYCLOGENESIS. SUBSIDENT NLY FLOW UPSTREAM OF THE PHASED
PERTURBATIONS WILL FACILITATE SFC RIDGING ACROSS PARTS OF THE GREAT
BASIN.

...PORTIONS OF WRN TX AND ERN NM...
ENHANCED MID-LEVEL FLOW WILL BE MANIFESTED AT THE SFC AS SSWLY TO
WSWLY WINDS OF 15-30 MPH WITH HIGHER GUSTS ACROSS THE REGION.
DOWNSLOPE EFFECTS WILL SUPPORT BOUNDARY-LAYER WARMING/DRYING WITH RH
VALUES EXPECTED TO FALL TO AROUND 10-20 PERCENT. IN GENERAL...THE
STRONGEST WINDS ARE EXPECTED TO BE CONFINED TO PARTS OF ERN NM TO
THE TX TRANS-PECOS REGION...BEING DISPLACED TO THE W OF LOWEST RH
VALUES RELEGATED TO LOCATIONS FARTHER E ACROSS PORTIONS OF WRN TX.
THIS WILL HAVE A TENDENCY OF LIMITING SPATIAL OVERLAP OF CRITICALLY
STRONG WINDS AND CRITICALLY LOW RH. SUCH OVERLAP MAY BE CONFINED TO
THE VICINITY OF THE GUADALUPE MOUNTAINS TO THE DAVIS MOUNTAINS.
HOWEVER...SOME VARIABILITY AMONGST MODEL SOLUTIONS REGARDING
LOW-LEVEL FLOW STRENGTH RENDERS LIMITED CONFIDENCE IN SUCH OVERLAP
OCCURRING. FURTHERMORE...AREAS OF RECENT PRECIPITATION AND FUEL
GREEN-UP/MOISTENING ACROSS THE REGION SHOULD MITIGATE THE FIRE
WEATHER RISK SUFFICIENTLY TO PRECLUDE CRITICAL DESIGNATION.

...LOWER CO RIVER VALLEY...
ENHANCED MID-LEVEL FLOW COUPLED WITH DIURNALLY STRENGTHENED VERTICAL
MIXING AND A TIGHTENED PRESSURE GRADIENT ON THE SRN FLANK OF THE SFC
RIDGING REGIME WILL SUPPORT WNWLY TO NLY SFC WINDS OF 15-20 MPH WITH
STRONGER GUSTS. RH VALUES WILL FALL TO AROUND 10-15 PERCENT IN
CONJUNCTION WITH THESE WINDS TO SUPPORT ELEVATED TO
BORDERLINE-CRITICAL FIRE WEATHER CONDITIONS. HOWEVER...WITHOUT
STRONGER LOW-LEVEL FLOW / A TIGHTER SFC PRESSURE GRADIENT...
CONFIDENCE IN CRITICALLY STRONG SUSTAINED WIND SPEEDS OCCURRING ON
ANY MORE THAN A BRIEF/SPOTTY BASIS IS TOO LIMITED FOR CRITICAL
DESIGNATION AT THIS TIME. ALSO...SOME AREAS OF PRECIPITATION DURING
THE PAST COUPLE OF WEEKS AND RELATED FUEL MOISTENING MAY LOCALLY
MITIGATE THE FIRE WEATHER RISK.

...SRN CA COASTAL RANGES AND ADJACENT FOOTHILLS...
THE SFC PRESSURE GRADIENT MAY TIGHTEN SUFFICIENTLY ON THE SWRN FLANK
OF THE SFC RIDGING REGIME TO SUPPORT THE DEVELOPMENT OF MODERATE TO
LOCALLY STRONG NELY WINDS AT THE END OF THE PERIOD -- I.E. LATE
SUNDAY NIGHT. THE STRONGEST WINDS ARE EXPECTED TO OCCUR THROUGH
FAVORED PASSES AND CANYONS. HOWEVER...SUCH INCREASES IN SFC WINDS
WOULD OCCUR WHEN NOCTURNAL COOLING AND RELATED INCREASES IN RH MAY
MITIGATE THE OVERALL FIRE WEATHER RISK SUFFICIENTLY TO PRECLUDE
HIGHLIGHTS.

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



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