204
AWUS01 KWNH 302052
FFGMPD
COZ000-NMZ000-AZZ000-UTZ000-010250-

Mesoscale Precipitation Discussion 0526
NWS Weather Prediction Center College Park MD
451 PM EDT Sun Jun 30 2024

Areas affected...Northern AZ...Northwest NM...South-Central and
Southeast UT...Western CO

Concerning...Heavy rainfall...Flash flooding likely

Valid 302050Z - 010250Z

SUMMARY...Deep monsoonal moisture pooling up across the
Intermountain West will drive scattered areas of heavy showers and
thunderstorms capable of producing very heavy rainfall rates.
Areas of flash flooding are likely, and especially given the
sensitive slot canyons and localized burn scar locations.

DISCUSSION...Convective initiation is well underway across areas
of northern AZ and will begin soon for areas of south-central to
southeast UT, northwest NM, and through western CO. Monsoonal
moisture continues to advance up across the region with deep layer
southerly flow focused around the western periphery of the
subtropical ridge over the southern Plains.

PW anomalies are on the order of 2 to 3+ standard deviations above
normal currently over northern AZ through southern UT and into
western CO. The deeper layer influx of moisture coupled with
orographics and increasing boundary layer instability will drive a
notable increase in the coverage of heavy showers and
thunderstorms over the next several hours.

SBCAPE values are greatest across central to northeast AZ,
northwest NM, southeast UT and into western CO, with magnitudes of
1000 to 2000 J/kg in place. Meanwhile, there is a belt of stronger
shear parameters focused over areas of southeast UT and western
CO, and these areas coupled with locally stronger moisture
convergence and presence of more differential heating boundaries
may allow for convection to be a little more focused and capable
of producing heavier totals heading into the evening hours.

Rainfall rates should reach 1 to 2 inches/hour with the more
organized cells, and any anchoring of convection near some of the
higher terrain may help drive some storm totals of as much as 2 to
4 inches. These higher rainfall rates and totals are likely to
result in some areas of flash flooding, with the greater concerns
once again focused on the sensitive slot canyons and burn scar
locations.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ABQ...BOU...FGZ...GJT...PUB...SLC...

ATTN...RFC...ABRFC...CBRFC...MBRFC...WGRFC...NWC...

LAT...LON   39810714 39330620 38280602 36640648 35160757
            35240920 36131072 36341225 37551202 38841080
            39470941 39780827