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Fire Weather Outlook Discussion
Issued by NWS
Issued by NWS
401 FNUS21 KWNS 131649 FWDDY1 Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1149 AM CDT Sat Jul 13 2024 Valid 131700Z - 141200Z Only minor adjustments were made to the isolated dry thunderstorm area in alignment with recent trends and coordination with local partners. Otherwise, the D1 Fire Weather Outlook remains on track with no changes needed to the Elevated risk areas. See previous discussion below for more information. ..Thornton.. 07/13/2024 .PREV DISCUSSION... /ISSUED 1250 AM CDT Sat Jul 13 2024/ ...Synopsis... Fire weather concerns will continue today across the western CONUS with dry lightning as the primary threat. Multiple days of very hot and dry conditions have cured fuels across much of the Great Basin and Pacific Northwest with ERC values well above the 90th percentile for most locations. Preconditioned fuels coupled with the potential for dry lightning may pose a considerable fire weather risk this afternoon and evening. A persistent upper ridge over the lower CO River Valley will continue to promote weak gradient winds for much of the Great Basin, though breezy conditions are anticipated across the Pacific Northwest/northern Rockies. ...Dry Thunder - CA into the Great Basin... 00 UTC soundings across the Southwest and West Coast sampled steep mid-level lapses and cool temperatures between 500-600 mb as well as appreciable mid-level moisture atop very dry conditions within the lowest 3 km. Thunderstorms ongoing at the time of the soundings were producing pockets of wetting rainfall - likely due to slow storm motions near 10 knots - but many areas received limited precipitation per MRMS QPE. GOES precipitable water imagery continues to show the northward expansion of 0.5-1.0 inch PWAT values into central NV. Although forcing for ascent will be fairly weak through the day, deep mixing will quickly erode any nocturnal MLCIN as ascent increases ahead of a weak mid-level perturbation. Thunderstorm development will likely begin across southern CA/NV and western AZ before spreading north through the afternoon, possibly reaching into southeast OR by the 22-02 UTC period. Likewise, thunderstorm coverage is expected to be greatest across the lower CO River Valley, but higher PWAT values and a higher probability for wetting rainfall in ensemble guidance limits confidence in the potential for a more widespread dry-lightning risk. Further north into central and northern NV (and adjacent states), storm coverage should be more sparse, but lower PWAT values, faster storm motions, the potential for strong convective outflows, and very receptive fuels should support a robust fire weather concern where storms develop. ...Pacific Northwest/northern Sierra and northern Rockies... Dry/windy conditions over the past 24-48 hours continue to promote active fire behavior east of the Cascades and into the northern Rockies per recent reports. A belt of stronger mid-level flow on the northern periphery of the upper ridge will support another day of breezy conditions as 20-30 knot flow between 700-500 mb is transferred downward amid deep diurnal mixing. Widespread RH reductions into the single digits and low teens are anticipated, and localized elevated fire weather conditions will be common; however confidence in a more prolonged, wind-driven fire weather threat remains highest across southeast OR and over portions of eastern ID/southwest MT. A more narrow zone of prolonged elevated fire weather conditions is anticipated in the lee of the northern Sierra Nevada within a modest downslope flow regime. ...Please see www.spc.noaa.gov/fire for graphic product... $$