FNUS28 KWNS 012200

Day 3-8 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
0458 PM CDT Mon Jun 01 2020

Valid 031200Z - 091200Z

A large-scale mid-level ridge is expected to prevail across the
CONUS through Day 3/Wednesday, before an upper low, meandering off
of the California coastline, merges with a broader trough aloft on
Day 4/Thursday and moves across the western CONUS Days
5-6/Friday-Saturday. Thereafter, broad cyclonic flow will persist
across the western CONUS, with embedded impulses pivoting around the
larger scale trough aloft Days 7-8/Sunday-Monday. Initially,
favorable fire weather conditions will remain relatively localized,
but with the approach of the aforementioned troughs, the subsequent
surface mass response will generate favorably dry and breezy
conditions across parts of the Intermountain west supportive of
wildfire spread. Deep-layer ascent associated with the cyclonic
upper flow pattern will also promote thunderstorm development across
portions of the Intermountain West. Elsewhere across the nation,
meaningful recent precipitation accumulations, forecast rainfall,
non-receptive fuels, or a moistened low-level airmass are expected
to preclude large-scale fire weather concerns.  

...Days 4-6/Thursday-Saturday...
With the approach of the first upper trough, dry and breezy westerly
flow is likely across portions of the Great Basin during the
afternoon hours Days 4-5/Thursday-Friday. 40% probabilities for
critical conditions have been introduced, with the possibility of
70% areas introduced in future outlooks should additional guidance
members depict stronger wind fields. Mid-range models diverge
somewhat Day 6/Saturday, as the initial trough ejects northeastward,
with some members depicting weaker flow aloft and subsequent surface
flow across the Great Basin/Four corners area, with other guidance
depicting stronger flow aloft and at the surface. Day 6/Saturday
critical probability delineations will be withheld until better
model consensus is achieved, with probabilities likely introduced
pending trends in stronger surface winds.

Isolated thunderstorms will be possible across eastern portions of
the Great Basin into the Four Corners regions Days
4-6/Thursday-Saturday. Some guidance members depict classic
inverted-V soundings extending up to 700-500 mb, indicative of
modest dry lightning potential. However, several days of previous,
slow moving storms have likely inhibited curing of fuels to a
degree, especially in the Four Corners region, where storms will be
most likely. 10% isolated dry thunderstorm areas will be withheld
until updated fuel guidance become available. 

...Days 7-8/Sunday-Monday...
As the secondary trough traverses the Internmountain West,
widespread dry and breezy surface flow will be possible across the
Great Basin, Four Corners, and central Rockies regions. Guidance
members however, disagree somewhat on upper trough placement and
timing, precluding critical probabilities for favorable surface fire
weather conditions until better model agreement is noted.

..Squitieri.. 06/01/2020

...Please see www.spc.noaa.gov/fire for graphic product...