980 FNUS21 KWNS 041637 FWDDY1 Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1137 AM CDT Tue Aug 04 2020 Valid 041700Z - 051200Z The previous forecast remains on track with only minor modifications needed based on recent ensemble guidance. See the previous discussion below for additional details. Elevated fire weather conditions are also possible over the western Mojave desert and low desert region of southeast CA. 15 to 25 mph winds were noted just above a strong inversion in morning observed soundings from southern CA. While sufficiently deep boundary-layer mixing will likely be confined to the desert terrain, where fuel loading is too low to support a robust fire weather threat, adjacent mountain ranges may experience downward mixing of these winds by late afternoon. Winds gusting upwards of 20-25 mph coupled with dry fuels may support periods of elevated conditions. At this time the overlap and duration of favorable weather conditions and receptive fuels remains too small to introduce an elevated risk area. ...Dry Thunderstorms... A dry thunderstorm or two remain possible from southern WY into western CO where morning GOES imagery and observed soundings show PWAT values between 0.5 to 0.6 inches along and west of the Rockies. Over the past couple of days this environment has supported a mixture of dry and wet thunderstorms, and this should remain the case today. While a few drier pockets were noted in GOES imagery across this region, HREF guidance suggests low probabilities for convection in these areas. Although a conditional risk for a dry thunderstorm exists, confidence in coverage and occurrence remains too low to include a risk area. ..Moore.. 08/04/2020 .PREV DISCUSSION... /ISSUED 0132 AM CDT Tue Aug 04 2020/ ...Synopsis... A weak upper-level trough will move ashore in central/northern California today. At the surface, a cold front across northwestern Wyoming will become more diffuse with a typical, but generally weak, surface trough within the Great Basin. Elevated fire weather concerns will be possible within southwestern Wyoming. Guidance has trended weaker with both the surface trough to the east as well as the mid-level flow aloft. That being said, confidence in widespread elevated conditions has decreased. Furthermore, the possibility for cumulus build-ups and a thunderstorm or two in the Uintas may also locally cool and increase RH in some areas. While lightning coverage is too low to warrant highlights, fire starts are possible given the condition of the fuels. Within southern Nevada, the developing surface trough may promote winds near 15 mph. Flow aloft will remain quite weak so these conditions may be intermittent in some areas. Fuels are anomalously dry for this time of year on account of very little monsoon activity thus far. ...Northern California into southwestern Oregon... With the trough approaching the area, a thunderstorm or two appears possible within the region during the late afternoon and evening. High resolution guidance is not aggressive in developing convection and, as mentioned, coverage would likely be low. These scenarios can produce more lightning than expected, but with the overall weakness of the shortwave trough, confidence is low enough that no dry thunderstorm area will be added. ...Please see www.spc.noaa.gov/fire for graphic product... $$
