Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Jul 20 2024 20:05:43

AWUS01 KWNH 202005
FFGMPD
AZZ000-UTZ000-210130-

Mesoscale Precipitation Discussion 0673
NWS Weather Prediction Center College Park MD
405 PM EDT Sat Jul 20 2024

Areas affected...Southern UT...Northern AZ...

Concerning...Heavy rainfall...Flash flooding possible

Valid 202005Z - 210130Z

SUMMARY...Above average moisture and instability across
susceptible higher plateau terrain/slot canyons pose spots of
..5"/hr and totals up to 1" and possible localized flash flooding.

DISCUSSION...CIRA LPW denotes enhanced moisture across S UT toward
the Four Corners in the 7-5H layer (.5") along/just downstream of
subtle embedded shortwave across S UT.  This moisture extends to
the surface in the 850-700mb layer along and just east of the Slot
Canyons and spine north into the Tushar and Pavani Range extending
toward the Sevier Valley and points east.  This brings totals over
1".   RAP analysis and AMVs from GOES-E/W suggest 30-35kt upper
level jet streak across E UT/S CO, with some weak right entrance
divergence across SW UT toward the area of concern.  However,
recent RAP analysis suggest above average instability with 1000
J/kg centered over E Garfield and Kane counties...which tends to
be the driver of excessive rainfall in the region.

Combined with aforementioned above average moisture and
thunderstorms will be capable of .5"/hr rates, maybe slightly
higher and highly localized totals up to 1" are possible. HREF
probabilities reach 25-30% for these magnitudes; and while not
extreme for the region, this has been above potential for the last
few weeks.   GOES-E Visible imagery indicates congested Tcu and
scattered CBs with  moderate lightning dotted across the higher
terrain where mountain circulation convergence was maximized.=20
While tops have not been cooler than  -30C.  Would expect a few
stronger updrafts over the next few hours capable of those .5-1"
totals.  Given weak 5+ kt inflow at cloud base, it is improbable
that multiple updraft cycles are going to be the mode; though
outflow should propagate to newer development.


Given the susceptible area where even less than .5"/hr rates are
problematic, would considered flash flooding possible though
coverage is not likely to be above average or even 'normal' for an
'active' monsoonal day in S UT/N AZ.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8JOafacIyctBnE8zxqHaPLxtacuQqBLa3D5eX-jMZSDoBJtycxoMN_9xgsRiRDFJsoPq=
IgPi55cfUvNmh-noVRQHdGc$  for graphic product...

ATTN...WFO...FGZ...GJT...SLC...VEF...

ATTN...RFC...CBRFC...NWC...

LAT...LON   39001144 38831082 38471005 38020929 37590942=20
            36851013 35760932 35210935 35151037 35701092=20
            36231099 36411104 36951133 37051163 36741183=20
            36221193 36261252 37121312 37701305 38241276=20
            38791238 38961198=20

=3D =3D =3D
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