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U.S. Day 1 Fire Weather Outlook
ZCZC SPCFWDDY1 ALL
FNUS21 KWNS 131634
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1134 AM CDT Thu Jun 13 2024
Valid 131700Z - 141200Z
The main change to the updated Day 1 Fire Weather Outlook was to add
isolated dry thunderstorm highlights to portions of central and
northern AZ. Fuels across this region are becoming critically
receptive to wildfire spread, with ERCs exceeding the 90th
percentile over several locations. Thunderstorms are expected to be
brief and sparse through much of the afternoon, with a slight
increase in coverage possible tonight. While thunderstorm coverage
may not reach 10 percent over any short interval of time, the
longer-term summation of strikes (wet or dry) over fuels primed for
ignitions suggests that isolated dry thunderstorm highlights are
warranted. Otherwise, the previous forecast remains on track, with
occasionally Elevated dry and breezy conditions still expected over
portions of the Lower Colorado River Basin.
..Squitieri.. 06/13/2024
.PREV DISCUSSION... /ISSUED 0159 AM CDT Thu Jun 13 2024/
...Synopsis...
A midlevel trough will advance eastward across southern CA, while a
related belt of moderate/strong southerly flow aloft overspreads
western AZ into southern NV and UT. This will promote a tightening
surface pressure gradient and 15-20 mph sustained southerly surface
winds across these areas. These winds, coupled with a deep/dry
boundary layer (single-digit RH) and receptive fuels, will favor
elevated to locally critical fire-weather conditions.
Additionally, isolated thunderstorms are possible during the late
afternoon into the overnight hours across portions of AZ into UT --
aided by ascent preceding the aforementioned midlevel trough. If
afternoon thunderstorms can develop, these storms would be
high-based in an environment characterized by a deep inverted-V
thermodynamic profile -- and isolated lightning-induced ignitions
would be possible. However, confidence in afternoon storm
development is low owing to very marginal instability, precluding
Dry Thunderstorm highlights at this time. Confidence in thunderstorm
development is higher during the overnight period, when a mix of
wet/dry storms are expected. However, increasing boundary-layer RH
and midlevel moisture may temper the overall threat of ignitions.
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U.S. Day 2 Fire Weather Outlook
ZCZC SPCFWDDY2 ALL
FNUS22 KWNS 131925
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0225 PM CDT Thu Jun 13 2024
Valid 141200Z - 151200Z
Isolated dry thunderstorm highlights have been added to portions of
Mogollon Rim and surrounding areas in central and northern Arizona
for tomorrow (Friday). Here, isolated high-based thunderstorms are
expected to initiate in the wake of earlier showers by afternoon,
just before the mid-level trough and associated upper-level support
drifts away from the region. While thunderstorms will be moving
slowly overall, they may pass over fuel beds that have recently
become critically receptive to wildfire spread, necessitating the
introduction of isolated dry thunderstorm highlights. Otherwise the
previous forecast (see below) remains on track.
..Squitieri.. 06/13/2024
.PREV DISCUSSION... /ISSUED 0200 AM CDT Thu Jun 13 2024/
...Synopsis...
A southern-stream midlevel trough, accompanied by moderate
south-southwesterly flow aloft, will advance east-northeastward
across the Southwest during the day. At the same time, a weak
surface low south of south-central NM will promote modestly breezy
westerly surface winds across southeastern AZ and southwestern NM.
Given a deep/dry boundary layer across the area (single-digit RH),
elevated to locally critical fire-weather conditions are expected.
The primary limiting factor for the addition of a Critical area is
marginal surface winds (15-20 mph), though if surface winds trend
upward, a Critical area could be warranted in future outlooks.
Farther north, strong deep-layer westerly flow in the base of a
midlevel trough will overspread the Northwest. The associated
downslope flow across the Cascades and Sierra will favor locally
dry/breezy conditions across portions of northwestern NV and eastern
WA/northeastern OR. As a result, elevated conditions are expected
for both areas, with locally critical conditions possible in
northwestern NV -- where 20-25 mph sustained westerly surface winds
are expected.
On the backside of the southern-stream midlevel trough, low/midlevel
offshore flow will gradually strengthen across southern CA. As a
result, locally breezy/gusty northerly surface winds will likely
overlap low RH across portions of southern CA during the overnight
hours, with locally elevated fire-weather conditions possible where
fuels are receptive to fire spread. An Elevated area was considered
for portions of the area, though the threat appears too localized
for such highlights at this time.
U.S. Day 3-8 Fire Weather Outlook
ZCZC SPCFWDD38 ALL
FNUS28 KWNS 132152
Day 3-8 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0452 PM CDT Thu Jun 13 2024
Valid 151200Z - 211200Z
Broad cyclonic mid-level flow will persist over the northwestern
quadrant of the CONUS through late next week as an upper ridge
dominates the central and eastern CONUS. Several days of
wildfire-spread potential are evident over the Interior West as
multiple mid-level troughs pivot around the broad cyclonic flow
aloft. The first in a series of mid-level troughs will overspread
the Pacific Northwest on Day 3 (Saturday), with dry and windy
conditions overspreading drying fuels to the lee of the Cascades,
and farther south across southern portions of the Great Basin. By
Days 4-5 (Sunday and Monday), a broader and more amplified mid-level
trough will traverse the Interior West, supporting dry and windy
conditions atop receptive fuels from portions of the California
Valley area, to the Great Basin and Desert Southwest. The best
chance for Critically dry and windy conditions atop receptive fuels
will be over southern Utah into much of northern and central Arizona
and far western New Mexico, where 70 percent Critical probabilities
have been added. Thereafter, the mid-level trough will depart the
region. Dry conditions will persist, but questions remain regarding
the strength of the surface wind field, precluding the addition of
Critical probabilities for Days 6-8 (Tuesday-Thursday).
..Squitieri.. 06/13/2024
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