Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Aug 20 2024 22:46:28

AWUS01 KWNH 202246
FFGMPD
AZZ000-210444-

Mesoscale Precipitation Discussion 0911
NWS Weather Prediction Center College Park MD
645 PM EDT Tue Aug 20 2024

Areas affected...portions of southern and eastern AZ

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

Valid 202244Z - 210444Z

Summary...Showers and thunderstorms across portions of eastern and
southern AZ are expected to persist for the next several hours
with some increase in coverage.  Hourly rain totals to 2" are
possible where cells merge or train.

Discussion...The combination of a warm core ridge near the border
of southeast NM and northwest TX and an upper low moving about 250
miles south of southeast AZ is bringing mid-level moisture to
portions of southeast AZ.  When combined with decreasing CIN and
daytime heating boosting ML CAPE up toward 1500 J/kg, showers and
thunderstorms have developed across portions of eastern AZ.=20
Precipitable water values are in the 1-1.3" range per GPS data.=20
Effective bulk shear, particularly across southeast AZ, has been
increasing with SPC mesoanalyses indicating 30 kt magnitude, which
is sufficient organize convection.

The expectation is for increasing convective coverage with time,
particularly for portions of southern AZ, as inflow into the
topography increases along with precipitable water values and MU
CAPE into the evening hours.  The mean flow is out of the
southeast to south, which would allow activity in the mountains to
drift into lower elevations and possibly carry activity across
northwest Mexico into the area with time.  The mesoscale guidance
appears underdone on convective coverage so far and is not overly
agreeable on location; believe the Canadian Regional has the best
coverage though amounts appear too light.  The available
ingredients suggest that hourly rain totals to 2" are possible
locally where cells merge, possibly train, or any random
mesocyclones manage to develop.  This would be problematic in any
burn scars, arroyos/dry washes, or urban areas.

Roth

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7d4LozsIx0tPIgvyZtJNxruq1O-JFzYLI4PHJulXNdyAE908dzQtMpgv783sACn9F8Zy=
F7XTmvWrZrVYVh5uH4I3Jt8$  for graphic product...

ATTN...WFO...FGZ...PSR...TWC...

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

LAT...LON   35871099 35840924 33330913 31120916 31041073=20
            31541257 32251356 33851255=20

=3D =3D =3D
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