ACUS11 KWNS 291757
SWOMCD
SPC MCD 291756
AZZ000-UTZ000-292030-

Mesoscale Discussion 2166
NWS Storm Prediction Center Norman OK
1256 PM CDT Sat Aug 29 2026

Areas affected...Arizona

Concerning...Severe potential...Watch unlikely

Valid 291756Z - 292030Z

Probability of Watch Issuance...5 percent

SUMMARY...Thunderstorms will increase in coverage through the late
afternoon hours across the central third of Arizona. The potential
for severe downburst winds should increase in tandem with convective
coverage. However, the severe wind threat should remain sufficiently
transient and isolated to preclude watch issuance.

DISCUSSION...Latest GOES imagery over the past 30-60 minutes has
shown a steady increase in coverage and depth of cumulus along with
increasing lightning counts across central to northern AZ.
Temperatures across the region have been running on the warm side of
the guidance envelope this morning and early afternoon, and this
stronger heating is likely the primary contributing factor for the
somewhat early onset (compared to most 12z solutions) of
surface-based convective initiation as inhibition is quickly eroded
via heating/mixing. Attendant to the strong heating, low-level lapse
rates are rapidly steepening to 8 to 9 C/km based on RAP
mesoanalysis estimates and 30-40 F dewpoint depressions observed
across the region. Consequently, low-level thermodynamic profiles
are becoming increasingly favorable for accelerating downdrafts near
the surface.

Regional VWPs are sampling very weak (less than 15 knot) winds
within the lowest 2-3 km and only modest flow aloft (generally 20-25
knots). This should promote poorly organized and outflow-dominant
convection with perhaps some tendency for clustering through the
late afternoon. While marginal/sub-severe hail is possible, the
primary hazard should be strong to severe outflow winds with the
deeper convective cores/more intense downbursts. Based on recent
RRFS solutions (which appear to be capturing low-level thermodynamic
conditions the best), embedded swaths of outflow winds as strong as
60-70 mph are possible.

Based on latest GOES/reflectivity imagery, central to north-central
AZ should see the severe wind threat increase through the next few
hours as convection continues to deepen. Further southeast, very
weak low-level convergence is noted in the surface wind field, and
a lack of cumulus suggests deep convection is not imminent. However, time-lagged CAM consensus is that convection should emerge between
19-21 UTC.

..Moore/Mosier.. 08/29/2026

...Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fjg!_1FTZmcUzawZsGImTXu2-bRRir1cC4W3YcyR1pmo5YDNZagIPM-ro3RM8InHowlI5rQ18yZ8FRxWVZdADA_xn00EFrI$ for graphic product...

ATTN...WFO...TWC...FGZ...SLC...PSR...VEF...

LAT...LON 33881349 36381320 36901303 37071261 37091177 36961144
36591113 36221101 34341052 32740991 32090984 31640989
31371005 31281039 31281087 31351127 31611158 32381201
33301312 33601341 33881349

MOST PROBABLE PEAK WIND GUST...55-70 MPH


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--- scorpsmtpd
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