SPC Day 2 Fire Weather Outlook

By Newsroom America Feeds at 15 Apr 14:41

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0140 PM CDT Sun Apr 15 2018 Valid 161200Z - 171200Z ...CRITICAL FIRE WEATHER AREA FOR MUCH OF THE SOUTHWEST...SOUTHERN AND CENTRAL ROCKIES...AND ADJACENT CENTRAL AND SOUTHERN HIGH PLAINS... ...CRITICAL FIRE WEATHER AREA FOR CENTRAL AND SOUTHERN WYOMING... High-end critical fire weather conditions remain possible across parts of the Southwest Day 2/Monday, as strong/gusty low-level flow develops amidst a dry air mass. While meteorological conditions support a larger Critical area, the lack of fuel receptiveness and/or uncertainty in receptiveness -- mainly across portions of Nevada, Utah, western Colorado, and Wyoming -- continues to be the primary limiting factor to a more robust fire weather threat in these areas. Primary changes with this update were to refine the Critical/Elevated fire weather areas over Wyoming, Colorado, and Utah based on additional fuel guidance and coordination from local NWS Weather Forecast Offices as well as the latest numerical weather guidance. While the aforementioned lack of fuel receptiveness limits a larger Critical area, local/spotty critical conditions are expected anywhere fuels become receptive within the Elevated fire weather area over portions of Utah, western Colorado, and Wyoming. Elsewhere, only minor adjustments were needed to Critical/Elevated areas based on trends in deterministic/ensemble guidance. See previous discussion below for more information on tomorrow's fire weather threat. ..Elliott.. 04/15/2018 .PREV DISCUSSION... /ISSUED 0244 AM CDT Sun Apr 15 2018/ ...Synopsis... Extensive, and potentially higher-end, fire weather conditions are expected in a large part of the southwestern CONUS Monday afternoon and evening. A longwave trough will migrate eastward across California and into the western Great Basin throughout the forecast period. As this occurs, mid-level flow will strengthen dramatically from Arizona northward to Montana, with 80-90 knot flow nearer a jet max over southern California. At the surface, a strong trough/cold front (trailing southwest from a low over Montana) will traverse portions of Nevada and northern Utah through the day. A lee trough will also develop in the Colorado/New Mexico Plains and strengthen throughout the day. ...Utah and western Colorado northward to central Wyoming... 20-30 mph southwesterly surface flow will develop in these areas during peak heating hours - with even stronger gusts to 60 mph possible in areas of western Utah. Critically low RH values will also develop - lowest along an axis from southeastern Utah into western Colorado where single digits will become common. The atmospheric conditions may exceed extremely critical thresholds at times and foster rapid rates of fire spread. However, fuels are not cured/critical on a widespread basis across the region. The critical delineations highlight portions of the area that have the greatest chance of fire activity due to cured/critical fuels and critical wind/RH. Surrounding this critical, an elevated delineation has been drawn to highlight areas of potentially higher-end atmospheric fire weather in the absence of widespread, critically dry fuels. These areas may be reconfigured in later outlooks as additional fuels guidance becomes available. ...Arizona and the western half of New Mexico... As stronger mid-level flow approaches this area, surface wind speeds will respond, ranging from 20-25 mph in western New Mexico to near 40 mph (and higher gusts) in northwestern Arizona. A dry airmass should persist across the entire region, with critically low RH values expected as early as 12Z especially in lower-elevation areas. Where dry/cured fuels exist, a critical fire weather threat is expected. ...Eastern Colorado, eastern New Mexico, far western Oklahoma, and the western third of Texas... The north-south oriented lee trough across the area will act to increase surface winds throughout the day, with 20-25 mph flow becoming common. Surface winds may be slightly higher in terrain-favored areas of southern Colorado into central New Mexico. A dry airmass will remain in place across the region, with single digit RH values becoming common across much of southeastern Colorado and eastern New Mexico. Slightly higher RH will exist with eastern extent - especially as a modified maritime tropical airmass begins to advect northward along and east of the highlighted areas. Nevertheless, critical RH values remain likely over a large part of the western third of Texas during peak heating hours. Widespread elevated to critical fire weather conditions will exist where fuels are dry and remain in a pre-greenup state. ...South Florida... Fuels remain dry in this region and a few fires have been noted in recent days via radar and satellite imagery. A cold front will traverse the region late on D1/Sun and usher in a drier low-level airmass amidst 15 mph northwesterly winds. However, the front will foster showers and thunderstorms in the region that will likely alter fuel states. If storms are not as widespread as anticipated, an elevated fire weather threat will result and a delineation will be needed in later outlooks. ...Please see www.spc.noaa.gov/fire for graphic product... Read more



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