SPC Day 1 Fire Weather Outlook

By Newsroom America Feeds at 15 Apr 12:55

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1153 AM CDT Sun Apr 15 2018 Valid 151700Z - 161200Z Relatively minor changes have been made to expand the Elevated fire weather area over Arizona/Nevada/Utah a bit farther north into Utah. High-resolution deterministic/ensemble guidance continues to suggest sustained surface winds of 15-20 mph (locally higher) will develop this afternoon amidst critically lowered RH values, which will promote Elevated fire weather conditions where fuels are receptive. While locally critical conditions remain possible -- especially in areas of terrain-enhanced low-level flow -- the spotty/brief nature of the stronger winds coupled with uncertainty in large-scale fuel receptiveness precludes a Critical upgrade. The forecast of Elevated fire weather conditions over western Oklahoma and southwestern Kansas remains on track. See previous discussion below for more information. ..Elliott.. 04/15/2018 .PREV DISCUSSION... /ISSUED 0136 AM CDT Sun Apr 15 2018/ ...Synopsis... A much quieter fire weather pattern will be in place today across the Lower 48, with elevated fire weather likely to occur in portions of the Southwest and also a small part of the southern Plains. At the mid-levels, shortwave ridging will dominate across the Southwest in between two distinct disturbances - 1) a closed mid-level low that will slowly migrate toward the western Great Lakes and 2) another longer-wave trough that will approach California. Downstream of the California trough, some enhancement of mid-level flow is expected - particularly across the Lower Colorado River Valley and southern Great Basin. At the surface, the pressure gradient should relax some across the Plains as a surface low centered over Ohio migrates away from the region. Meanwhile, a low over Oregon - and a trough extending southward toward Arizona - will strengthen throughout the day. ...Western Oklahoma and a small part of southwestern Kansas... Latest high-resolution guidance suggests that 15 mph northwesterly surface flow will develop during peak heating as temperatures rise into the 50s and low 60s F. Fuels are dry and a few large fires continue across the region. Forecast soundings indicate that RH values could fall to as low as 12% amidst 7-14F dewpoints. These dry, breezy conditions support the ongoing elevated fire weather delineation. ...Northwestern Arizona into southern Nevada and southwestern Utah... The combination of the strengthening surface trough across the region, modest increase of mid-level flow, and vertical mixing processes will promote areas of 15-25 mph southerly surface winds during peak heating hours across the area. Concurrently, RH values should fall below critical thresholds areawide and fall perhaps into the single digits. The duration of critically strong surface winds should be brief enough to preclude any upgrades at this time, although observational trends and newer model guidance will be monitored in later outlook updates. ...Please see www.spc.noaa.gov/fire for graphic product... Read more



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