Colorado Mesoscale Discussion

Areas affected…west AZ…southeast UT…NM…southern CO

Concerning…Heavy rainfall…Flash flooding possible

Valid 091941Z – 100141Z

Summary….Scattered convection will continue to blossom across
the region through the next several hours with differential
heating and synoptic scale lift moving through the region to
promote lift. Some of these showers and thunderstorms will drop
moderate to heavy rain over terrain, saturated soils and/or burn
scars leading to the potential for flash flooding.

Discussion…Disturbances will continue to move north from
northwest Mexico as troughing in the west continues to feed
monsoonal moisture into the region. This moisture will feed into
the southern Rockies through the evening. Aloft, marginal
divergence is noted, especially across AZ into CO, associated with
a weak jet axis/right entrance region. At the surface, a weak low
and troughing is noted across southern UT/western AZ. The main
features to help enhance lift is aided by the earlier cloud cover
which led to differential heating across the terrain. With CAPE
values between 500-1000 J/kg and precipitable water above 1 inch
to the south, especially into southern AZ, feel hourly rain rates
may exceed 1.5 inches in some locations. We have already observed
rain rates in AZ around 1 inch/hour.

Storm motions initially will be slow to move off the terrain, but
with weak 700mnb flow overall, expect the outflows to help move
convection into the desert/valleys in time. Therefore, expect
convection along the higher terrain to potentially be problematic.
Also, convection may merge and or train briefly also exacerbating
rain rates/storm total QPF. With lower FFG in this region and
vulnerable soils given the terrain and residual burn scars, feel
there is a flash flood potential, albeit fairly localized over the
strongest/slowest convection.

Given the eastward progression of these storms across northern
NM/southern CO combined with sufficient lift and better
instability to the east, expect some of these storms to converge
into a cluster across portions of fast southeast CO toward the
panhandle of TX/OK through the next couple of hours. How this
evolves is a bit uncertain at this time, but the overall threat
for flash flooding may be minimized by the overall quick storm


…Please see for graphic product…



LAT…LON 38270357 36860279 35970453 33140476 32620772
32581071 33601186 34771214 36371233 37471132

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