329 FNUS22 KWNS 191849 FWDDY2 Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1248 PM CST Tue Jan 19 2021 Valid 201200Z - 211200Z The forecast remains on track for portions of southern California, as RH recoveries across the area suggest that mainly Elevated criteria surface conditions will persist past 12Z Wednesday. Similarly, across the Plains states, RH varies considerably among guidance members. Given the modest receptiveness of fuels and surface westerly winds remaining below 25 mph on a widespread basis, Elevated highlights have been withheld this outlook given the lack of confidence for more widespread RH below 25% across the central Plains. Lastly, 30-40% RH may be observed by afternoon peak heating across portions of the Carolinas, Georgia, and the Florida Peninsula, but weak winds preclude fire weather highlights despite modestly receptive fuels in place. ..Squitieri.. 01/19/2021 .PREV DISCUSSION... /ISSUED 0146 AM CST Tue Jan 19 2021/ ...Synopsis... A stalled synoptic low off the coast of southern California/Baja California is forecast to weaken through Wednesday evening, but will continue to support strong offshore flow and a fire weather concern for southern California for much of the day. Across the central CONUS, a surface trough associated with a Canadian clipper low will move southeastward through the day, ushering in breezy and dry conditions for portions of the Plains. ...Coastal southern California... Forecast guidance remains in good agreement that a -5 to -6 mb LAX-DAG pressure gradient will remain in place for much of Wednesday across southern CA as the synoptic low stalls offshore. Sustained winds near 30-45 mph (gusting to 50-60 mph) appear likely for portions of Los Angeles and Ventura counties with slightly weaker winds in the peripheral coastal areas. Winds will be strongest during the morning, and are expected to gradually weaken through the evening/overnight hours. Despite the persistent strong winds, relative humidities will likely improve through the day as moist air filters into the region. Cloud cover and scattered rain showers will further limit RH reductions for far southern CA where winds will likely remain elevated. Ensemble and deterministic guidance show humidity values will most likely improve into the 20-30% range for most coastal areas, but reductions as low as 15% are possible where downslope warming/drying can persist. Given the expected RH improvements, elevated fire weather conditions appear most likely, but transient/localized critical conditions are possible during the afternoon. ...central Plains... Northwesterly winds are forecast to increase to around 15-20 mph across the central Plains in the wake of a passing surface trough. Although temperatures will remain on the cool side, dry air advection and slight downsloping effects will allow RH values to fall to near 20% across the broader WY/SD/NE region. This may allow for areas of elevated fire weather conditions during the afternoon hours when diurnal heating and boundary-layer mixing are maximized. However, fuels across this region are only marginally receptive (10-hour fuel moisture values in the low teens and ERC values in the 50-60th percentiles) after light precipitation over the past 24 hours. Because of this, no risk areas are introduced for this outlook. Highlights may be needed in subsequent outlooks if guidance trends windier or drier. ...Please see www.spc.noaa.gov/fire for graphic product... $$
