MD 1579 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR SOUTHEASTERN ARIZONA AND ADJACENT SOUTHWESTERN NEW MEXICO
Mesoscale Discussion 1579
NWS Storm Prediction Center Norman OK
0158 PM CDT Thu Jul 11 2024
Areas affected…southeastern Arizona and adjacent southwestern New
Mexico
Concerning…Severe potential…Watch possible
Valid 111858Z – 112200Z
Probability of Watch Issuance…40 percent
SUMMARY…Thunderstorms developing across the higher terrain may
generate strengthening outflow spreading southwestward across lower
elevations, toward the central/southeastern Arizona international
border area, through 2-4 PM MST. This probably will be accompanied
by strong to occasionally severe wind gusts and blowing dust. While
it is not clear that this will require a severe weather watch,
trends are being monitored.
DISCUSSION…While morning soundings indicated some increase in
precipitable water across the region over the past 24 hours or so,
low-level moisture remains seasonably modest with surface dew points
across much of the lower deserts forecast to fall into the mid 40s
to near 50 F by peak afternoon heating and boundary-layer mixing.
Still, across the higher terrain, including the Mogollon Rim
vicinity of eastern central Arizona into southwestern New Mexico,
the moisture has been sufficient to support deepening convective
development and the initiation of thunderstorm activity.
Beneath a belt of northeasterly to easterly mid-level (cloud-bearing
layer) flow (initially convectively augmented, but now weakening to
around 20-25 kt or so), guidance suggests that additional
thunderstorm development is increasingly probable during the next
few hours across the higher terrain of southeastern Arizona into
Sonora. However, upslope into/across the Mogollon Rim vicinity may
support the most prominent clustering and upscale growth of
convection.
Gradually, aided by increasing precipitation loading and sub-cloud
evaporative cooling, strengthening downdrafts appear likely to
consolidate into larger-scale scale southward and southwestward
propagating outflow, which may be accompanied by increasing
potential for strong surface gusts. Given the weak CAPE evident in
forecast soundings for the strongly heated and increasingly
deeply-mixed boundary layer in lower elevations, the extent of
renewed convective development along/above the outflow remains
unclear. However, it appears possible that this could be sufficient
to support strong to locally severe gusts into the lower deserts and
across the international border by early evening.
..Kerr/Guyer.. 07/11/2024
…Please see www.spc.noaa.gov for graphic product…
ATTN…WFO…EPZ…TWC…PSR…
LAT…LON 33511079 33371017 33150957 33060894 32980839 32400803
31300905 30971066 31581194 32091125 33251122 33511079
