FNUS21 KWNS 041637

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/

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

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...