SPC Day 1 Fire Weather Outlook

By Newsroom America Feeds at 26 Sep 2017

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0158 AM CDT Tue Sep 26 2017 Valid 261200Z - 271200Z ...Synopsis... A highly amplified upper-level trough located over the western CONUS is forecast to weaken throughout the day, with an upper-level low developing in the vicinity of the lower CO River Valley, coincident with the development of an upper-level ridge in the Pacific Northwest. These features should help to sustain modestly enhanced northerly mid- to upper-level flow of 35-45 kt over much of CA. Surface high pressure is forecast to be present over portions of the Pacific Northwest and Great Basin regions along with warm/dry conditions. ....Portions of the Sacramento Valley and Adjacent Coastal Ranges of Northern CA... Elevated fire-weather conditions are likely this afternoon across portions of the Sacramento Valley and adjacent Coastal Ranges of northern CA. Diurnal heating and vertical mixing should promote an increase in northerly surface wind speeds approaching 15 mph along with RH values decreasing into the 10-20% range, supporting an elevated designation across this region. ....Portions of Southern CA... Elevated fire-weather conditions should continue to develop across portions of southern CA throughout the early morning today, with less favorable conditions expected throughout the afternoon and evening as the surface pressure gradient relaxes somewhat. These elevated fire-weather conditions may redevelop early Wednesday morning. A modest surface pressure gradient is developing early this morning, bringing sustained offshore surface winds around 15-20 mph across portions of the area, with stronger gusts up to 25-30 mph occurring in the mountains/foothills. Several 06Z surface observations in this region are already exhibiting elevated fire-weather conditions, with RH values falling near or just below 20%. Locally critical fire-weather conditions may occur for a brief period this morning mainly in higher terrain, given the combination of strong winds approaching 20 mph, RH values becoming minimized around 10-15%, and dry fuels. However, these conditions are not expected to occur for more than 3 continuous hours on any more than an isolated basis. Therefore, no critical area has been introduced. ..Karstens/Gleason.. 09/26/2017 ...Please see www.spc.noaa.gov/fire for graphic product... Read more



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