Storm Prediction Center Day 1 Fire Weather Outlook
Created: Fri Jul 20 16:28:02 UTC 2018 ( | )
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ZCZC SPCFWDDY1 ALL FNUS21 KWNS 201626 Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Fri Jul 20 2018 Valid 201700Z - 211200Z An elevated area was added for portions of far southwest Oregon/northwest California where gusty north-northeast winds (sustained 15-20 mph) will overlap with RH values of 15-25% this afternoon/evening. The elevated area over central Oregon was expanded farther south as a dry cold front should increase winds this evening as it passes through the region. The ongoing fire activity within these two elevated areas are likely to be exacerbated by these dry/windy conditions and antecedent dry fuels. The isolated dry thunderstorm area was expanded southward as monsoonal moisture continues slowly moving northward via latest surface/upper-air observations and water vapor imagery. Overall, the forecast looks on track and please see discussion below for more details. ..Nauslar.. 07/20/2018 .PREV DISCUSSION... /ISSUED 0204 AM CDT Fri Jul 20 2018/ ...Synopsis... A long-wave upper-level trough will move into the Pacific Northwest today. In the meantime, an upper-level ridge will build across the Front Range of the Rockies. An area of enhanced 40 to 50 knot mid-level flow will develop across much of the Pacific Northwest and could lead to several areas of elevated fire weather concern. In addition, thunderstorms will develop across much of the Desert Southwest, Great Basin, and Colorado Rockies. Some of these thunderstorms will be on the drier side along the northern and western periphery of the richer moisture. ...Columbia River Basin... Downslope flow and deep mixing will lead to sustained winds around 15 mph across much of the Columbia River Basin. These winds, combined with RH values of 15 to 20 percent, will lead to elevated fire weather conditions. Wind speeds may be slightly higher in some of the gaps in the Cascades, but the marine influence west of the Cascades will lead to slightly higher RH values (25 to 30 percent) in these locations. ...Southern Idaho... Sustained winds will approach 15 mph during the afternoon today as deep mixing transports stronger mid-level winds towards the surface across much of the Snake River Valley into portions of the Bitterroot Mountains. RH values will be 10 to 15 percent across much of this area leading to elevated fire weather conditions. ...Northern Montana... Downslope flow and deep mixing will lead to increasing surface winds into the afternoon east of the Lewis Range. In addition, RH values will drop to the 15 to 20 percent range. This will lead to elevated fire weather conditions for at least a few hours on Friday. ...Eastern California into the northern Great Basin... An area of dry thunderstorms is possible along the periphery of the greater monsoon moisture from far eastern California across northern Nevada and Utah and into far southwest Wyoming. Kept the isolated dry thunderstorm delineation to areas which have seen mostly limited rainfall (< 0.25") over the past 7 days where PWAT values are less than an inch and storms are expected. ...Southern Plains... A heat wave in the southern Great Plains will lead to dry conditions during the afternoon hours for much of west eastern New Mexico, West Texas, and western and central Oklahoma. RH values are expected to drop into the 15 to 20 percent range during the afternoon with an increasing surface wind. Southerly surface winds will strengthen to around 15 mph. This combination of gusty surface winds and low relative humidity values warrants elevated fire weather concerns across much of the southern High Plains into western and central Oklahoma. While some of this area has seen significant rainfall over the past 7 days, coverage of these storms has been spotty, and hot weather the past few days has led to significant drying of fine fuels. ...Please see www.spc.noaa.gov/fire for graphic product...
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