190  
FNUS22 KWNS 020701  
FWDDY2  
 
DAY 2 FIRE WEATHER OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK  
0100 AM CST SAT DEC 02 2017  
 
VALID 031200Z - 041200Z  
   
..SYNOPSIS
 
 
AN UPPER TROUGH WILL MOVE EASTWARD ACROSS THE WESTERN STATES TO THE  
ROCKIES/HIGH PLAINS BY LATE SUNDAY NIGHT. ENHANCED MID-LEVEL WINDS  
ASSOCIATED WITH THIS TROUGH WILL OVERSPREAD PARTS OF THE  
CENTRAL/SOUTHERN HIGH PLAINS BY SUNDAY AFTERNOON. AT THE SURFACE, A  
LOW SHOULD FORM AHEAD OF THE UPPER TROUGH ACROSS EASTERN WY AND  
VICINITY, WITH LEE TROUGHING EXTENDING ALONG MUCH OF THE  
CENTRAL/SOUTHERN HIGH PLAINS. THIS SURFACE LOW SHOULD DEVELOP  
EASTWARD ACROSS THE NORTHERN HIGH PLAINS THROUGH THE PERIOD. AN AREA  
OF SURFACE HIGH PRESSURE WILL STRENGTHEN IN A SUBSIDENT REGIME IN  
THE WAKE OF THE UPPER TROUGH ACROSS PARTS OF THE WESTERN CONUS, WITH  
THE ONSET OF A PROLONGED OFFSHORE WIND EVENT LIKELY BEGINNING ACROSS  
PORTIONS OF SOUTHERN CA LATE SUNDAY INTO EARLY MONDAY MORNING.  
   
..PORTIONS OF SOUTHERN CA
 
 
STRONG/GUSTY SUNDOWNER WINDS SHOULD OCCUR ACROSS SOUTHERN SANTA  
BARBARA COUNTY IN CA SUNDAY EVENING AS A FAVORABLE PRESSURE GRADIENT  
SUPPORTS THE INITIAL DEVELOPMENT OF OFFSHORE FLOW. SUSTAINED WINDS  
OF 20-25 MPH APPEAR PROBABLE, WITH HIGHER GUSTS OF 40-50 MPH  
POSSIBLE IN THE MOUNTAINS/FOOTHILLS. THERE REMAINS SOME UNCERTAINTY  
REGARDING THE DEGREE OF RH REDUCTION WITH THIS SUNDOWNER EVENT, WITH  
MOST GUIDANCE SUGGESTING RH VALUES LOWERING INTO THE 15-20% RANGE BY  
LATE SUNDAY EVENING. HAVE THEREFORE OPTED TO INCLUDE MOST OF  
SOUTHERN/CENTRAL SANTA BARBARA COUNTY IN AN ELEVATED FIRE WEATHER  
AREA FOR DAY 2/SUNDAY. IF HIGH-RESOLUTION GUIDANCE SUGGESTS RH  
VALUES WILL BECOME LOWERED BELOW 15% FOR A PROLONGED PERIOD SUNDAY  
EVENING INTO EARLY MONDAY MORNING, THEN A SMALL CRITICAL AREA MAY BE  
NEEDED.  
 
ELEVATED FIRE WEATHER CONDITIONS WILL LIKELY OCCUR ELSEWHERE ACROSS  
PARTS OF COASTAL SOUTHERN CA AS THE SURFACE HIGH DESCRIBED ABOVE  
DEVELOPS INTO THE GREAT BASIN AND THE PRESSURE GRADIENT STRENGTHENS  
ACROSS THIS REGION. LATEST GUIDANCE INDICATES A SUFFICIENT LAX-TPH  
AND LAX-DAG PRESSURE GRADIENT TO SUPPORT 15-30 MPH SUSTAINED  
NORTHEASTERLY OFFSHORE WINDS ACROSS THE MOUNTAINS/FOOTHILLS OF  
VENTURA/LOS ANGELES/ORANGE COUNTIES AND VICINITY BEGINNING LATE  
SUNDAY NIGHT AND CONTINUING THOUGH EARLY MONDAY MORNING (END OF THE  
DAY 2 PERIOD). STRONGER GUSTS WILL BE LIKELY IN HIGHER TERRAIN. RH  
VALUES WILL BECOME LOWERED TO NEAR-CRITICAL LEVELS (15-20%) THROUGH  
DOWNSLOPE WARMING/DRYING PROCESSES, AND THERE APPEARS TO BE AT LEAST  
SOME POTENTIAL FOR POCKETS OF SUB-15% RH VALUES ACROSS THIS REGION.  
FOR NOW, WILL DEFER INTRODUCTION OF A CRITICAL AREA DUE TO CONTINUED  
UNCERTAINTY REGARDING CRITICALLY LOWERED RH VALUES LATE IN THE DAY  
2/SUNDAY PERIOD.  
   
..PORTIONS OF THE CENTRAL/SOUTHERN HIGH PLAINS
 
 
STRONG/GUSTY SURFACE WINDS WILL DEVELOP ALONG THE LEE TROUGH  
MENTIONED ABOVE ACROSS PARTS OF EASTERN NM INTO THE TX/OK  
PANHANDLES, SOUTHEASTERN CO, AND SOUTHWESTERN KS SUNDAY AFTERNOON AS  
ENHANCED SOUTHWESTERLY WINDS EMBEDDED WITH A MID-LEVEL JET BECOME  
DIURNALLY MIXED TO THE SURFACE. SUSTAINED WIND SPEEDS AROUND 20-25  
MPH APPEAR LIKELY, WITH SOME HIGHER GUSTS POSSIBLE. EVEN WITH  
LOW-LEVEL DOWNSLOPE TRAJECTORIES SUPPORTING SOME WARMING/DRYING OF  
THE BOUNDARY LAYER, RH VALUES ARE FORECAST TO BECOME ONLY MARGINALLY  
LOWERED TO AROUND 20-30% THROUGH PEAK HEATING SUNDAY AFTERNOON.  
LOCALLY ELEVATED FIRE WEATHER CONDITIONS COULD DEVELOP ACROSS  
PORTIONS OF THIS REGION WHERE FUELS ARE DRY AND RH VALUES NEAR 20%  
FOR AN HOUR OR TWO. HOWEVER, THE LACK OF AN EVEN WARMER/DRIER  
FORECAST LOW-LEVEL AIRMASS (WITH WIDESPREAD RH VALUES OF 15-20%)  
PRECLUDES THE INTRODUCTION OF AN ELEVATED AREA AT THIS TIME.  
 
..GLEASON.. 12/02/2017  
   
..PLEASE SEE WWW.SPC.NOAA.GOV/FIRE FOR GRAPHIC PRODUCT
 
 

 
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab SPC Page Main Text Page