Storm Prediction Center Day 2 Fire Weather Outlook
Created: Fri Dec 15 19:59:03 UTC 2017 ( | )
Click for Day 2 FireWX Areal Outline Product (KWNSPFWFD2)
ZCZC SPCFWDDY2 ALL FNUS22 KWNS 151958 Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Fri Dec 15 2017 Valid 161200Z - 171200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF CENTRAL CALIFORNIA... ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF SOUTHERN CALIFORNIA... Ongoing forecast is on track with minimal changes. Widespread elevated to critical fire weather conditions are expected across much of California as strong northerly flow combines with 10-20% RH during peak heating hours. Areas of dry fuels will support rapid fire spread with any fires that do develop. Farther east, the elevated area across the central/southern Plains has been expanded eastward a bit to include more of northeastern Oklahoma and adjacent portions of Kansas. Current guidance only depicts minimum RH values at around 30% or so in these newly included areas, although some concern exists that deeper boundary layer mixing will result in lower RH values than currently expected. Winds across this area will gust above 20-25 mph at times during the afternoon. See the previous discussion below for more information. ..Cook.. 12/15/2017 .PREV DISCUSSION... /ISSUED 0106 AM CST Fri Dec 15 2017/ ...Synopsis... Strong northerly deep-layer flow on the back side of an amplifying upper trough over the western U.S. will overspread much of the California on Saturday. At the surface, a cold front will move southeast across the Great Basin and high pressure will build over the region late in the period. Further east, a lee low will develop over the central High Plains and a tightening surface pressure gradient will aid in the development of breezy south/southwesterly winds across portions of the central and southern Plains. ...Portions of Central into Northern CA... Elevated fire weather conditions will be widespread from the central coast into the Sacramento and portions of the San Joaquin Valleys as gusty north to northeast winds overspread the region and RH values fall into the 15-35 percent range. In the vicinity of the Bay Area mountains and foothills, critical fire weather conditions are expected to develop during the morning hours and continue into Sunday morning. The strongest north winds are expected to align with lower RH values in this area. Sustained north/northeast winds of 20-30 mph with higher gusts will be possible in the mountains and foothills, where RH values will fall into the 15-25 percent range. Winds will remain gusty into the overnight hours and RH recovery will be poor in the mountains. ...Portions of Southern CA... As high pressure settles back into the Great Basin Saturday night, the pressure gradient will again become favorable for gusty offshore winds. Wind speeds are expected to increase across the L.A. and Ventura County mountains after dark and sustained speeds of 20-30 mph with higher gusts are expected. RH values across the mountains will remain low, in the 10-20 percent range. As a result, critical fire weather conditions are expected to develop once again Saturday night into Sunday morning. ...Portions of the Central/Southern High Plains... Breezy south/southwest winds are expected during the afternoon as a lee low develops over eastern CO. A dry airmass will be in place and warm afternoon temperatures resulting in boundary-layer mixing to around 2-3kft will allow for RH values falling into the 20-30 percent range. Sustained wind speeds of 10-15 mph with higher gusts will result in widespread elevated to locally critical fire weather conditions during the afternoon. ...Please see www.spc.noaa.gov/fire for graphic product...
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