Fire Weather Outlook Discussion
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FNUS22 KWNS 271646

Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1145 AM CDT Tue Jun 27 2017

Valid 281200Z - 291200Z


Primary changes to the Day-2 Fire Weather Outlook are as follows:

1. The Critical area has been expanded eastward into additional
portions of western CO and northwest NM. The latest model guidance
suggests 20-30 mph southwesterly to westerly surface winds combining
with 4-12 percent RH amid dry fuels across these areas added to
Critical designation.

2. An Elevated area has been added for the southern CA mountains and
adjacent foothills. Based on the latest model guidance, continued
low RH and modestly enhanced winds are expected into
Day-2/Wednesday -- prolonging the duration of enhanced fire-weather

3. The Isolated Dry Thunderstorm area has been expanded westward
across northern UT, southeast ID, and into extreme northeast NV. The
latest model guidance suggests sufficient buoyancy associated with
deep, well-mixed boundary layers for the isolated dry-thunderstorm
risk to extend farther west, as low-amplitude midlevel disturbances
and related ascent cross the region in westerly flow aloft.

No other changes have been made to the ongoing forecast.

..Cohen.. 06/27/2017

.PREV DISCUSSION... /ISSUED 0218 AM CDT Tue Jun 27 2017/

Predominately zonal upper pattern will exist across the CONUS at the
beginning of the period (12Z Wednesday). Low-amplitude shortwave
trough will track eastward through the upper Midwest and upper Great
Lakes while another shortwave trough drops southeastward through the
northern Rockies during the second half of the period. Enhanced
westerly flow aloft across the Great Basin/central Rockies and warm
temperatures will help keep surface pressures low across much of the

...AZ...Great Basin...Central/Northern Rockies...
While cooler than temperatures observed during much of the past
week, highs are still expected to be 5 to 10 degrees above average
across much of the region on Wednesday. The airmass over the region
also remains very dry, with afternoon RH values in the single digits
expected areawide. Increased mid-level flow amidst a tight surface
pressure gradient and deep boundary-layer mixing will support gusty
winds. Strongest winds (i.e. 20-30 mph) are expected from northern
AZ through much of southern and central UT. These dry and windy
conditions amidst dry fuels will support a critical fire weather
threat. Elevated to locally critical conditions are anticipated
across the remainder of the region.

In addition to the wind-driven fire weather threat, portions of
southern WY, far northeast UT, and northwest/north-central CO could
see isolated dry thunderstorms within the modestly unstable but
deeply mixed environment across the region. Enhanced mid-level flow
will also contribute to fast storm motions, further reducing
precipitation amounts at the surface.

...Please see for graphic product...

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