ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 291959
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0159 PM CST Sun Nov 29 2020
Valid 301200Z - 011200Z
The elevated area has been extended up the coast into portions of
Santa Barbara and San Luis Obispo Counties, mainly for late in the
period when the pressure gradient may support stronger winds in
these areas. Otherwise, the previous forecast remains on track, with
elevated to locally critical conditions possible across
terrain-favored regions of southern CA. See the previous discussion
below for more information.
...Colorado Front Range into eastern Wyoming/Nebraska Panhandle and
Locally elevated conditions are expected for a portion of eastern WY
into the NE Panhandle, where strong downslope flow will support RH
dropping to near or below 20% amidst sustained winds of 15-25 mph
(with higher gusts). With temperatures expected to remain relatively
cool and uncertainty regarding the duration of any elevated
conditions, no Elevated area has been included at this time.
Locally elevated conditions will be possible southward along the CO
Front Range, though winds should be weaker with southward extent.
Locally elevated conditions will also be possible associated with
downslope flow into portions of central MT.
Relatively strong low-level easterly flow is expected to develop
Monday morning across parts of southern AZ, though winds are
expected to weaken during the afternoon prior to peak heating.
Locally elevated conditions will be possible, though confidence in a
sufficient duration of any such conditions is too low to include an
Elevated delineation at this time.
.PREV DISCUSSION... /ISSUED 0142 AM CST Sun Nov 29 2020/
A dominant surface high over the central CONUS will gradually shift
south through the day Monday. This will have the affect of bringing
calmer and cool conditions to much of the Plains as well as help
weaken the pressure gradient over the Southwest. Fire weather
concerns will largely be limited to locations that typically
experience terrain-augmented winds across parts of southern
California and possibly along the foothills of eastern Wyoming.
The gradual shift of the surface high from the central
Rockies/northern Great Basin into the southern High Plains will help
alleviate the offshore pressure gradient across southern California
to a degree. Despite an improving synoptic pattern, mid-level winds
are forecast to strengthen as a progressive upper-level trough
glances the region to the north. Afternoon boundary-layer mixing
will likely support 15-25 mph winds down to the surface within the
higher elevations, which, when coupled with antecedent low RH values
and dry conditions, will foster areas of elevated fire weather
conditions through Monday afternoon. Surface high pressure is
forecast to become re-established over the northern Great Basin by
late Monday/early Tuesday in the wake of Monday's upper-level trough
passage. This may result in a re-intensification of the offshore
pressure gradient and allow for pockets of elevated fire weather
conditions to linger into early Tuesday.
The same upper-level shortwave trough that will bring an uptick in
mid-level winds to the Southwest will also help drive lee troughing
along the northern High Plains Monday afternoon. This troughing,
combined with increasing 850-700 mb westerly flow, will help drive
areas of gusty west/southwesterly winds. Downslope warming and
drying may allow a few locations to see elevated fire weather
conditions, but this is expected to largely be confined to the
immediate leeward side of elevation features. Recent ensemble
guidance suggests that the most likely location for this to occur is
across the foothills of eastern WY where ERC values are slightly
elevated, but a lack of support from deterministic RH solutions and
only modestly receptive fuels yields low confidence in the fire
weather potential at this time. As such, no highlights are
introduced, but trends will continue to be monitored.
...Please see www.spc.noaa.gov/fire for graphic product...
CLICK FOR DAY 2 FIREWX AREAL OUTLINE PRODUCT (KWNSPFWFD2)