Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Mar 22 2023 03:57:06

AWUS01 KWNH 220357
FFGMPD
AZZ000-220930-

Mesoscale Precipitation Discussion 0116
NWS Weather Prediction Center College Park MD
1156 PM EDT Tue Mar 21 2023

Areas affected...central AZ

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

Valid 220354Z - 220930Z

Summary...An increase in rainfall rates to near 0.5 in/hr is
expected for the upslope regions of the Mogollon Rim through 09Z.
Additional peak rainfall totals of 1-2 inches could result in
areas of flooding/flash flooding atop saturated soils.

Discussion...Regional radar imagery across much of central AZ
showed steady rain continued to fall as of 03Z containing peak
rainfall rates from earlier in the day on Tuesday in the 0.1 to
0.35 in/hr range. Gauge reports of rainfall over the past 18-24
hours have shown about 1-3 inches across southern Coconino,
northern Gila and Yavapai counties and USGS data along area
streams and rivers showed well above average streamflows.
Precipitable water values per GPS data showed ~0.5 inches in
central AZ increasing to about 1 inch along the AZ/MX border.
Instability over the region was limited however, even within the
upstream environment measured at 22Z from a Yuma sounding with
MUCAPE of 78 J/kg and dewpoints of 5 and 0 C at 850 and 700 mb
respectively.

As a Pacific closed low over central CA and related surface cold
front, analyzed over western AZ at 03Z, continues to move eastward
tonight, 850-700 mb flow from the SSW is forecast by the RAP to
increase about 10 kt to near 40 kt through 06-08Z over portions of
south-central AZ. The eastward advancement of the upper low and
surface front will be accompanied by subtle cooling of mid-level
temperatures and an increase in 850-700 mb moisture, helping to
support weak instability of 100-200 J/kg. The combination of weak
instability and increasing orographic enhancement should support
peak rainfall rates near 0.5 in/hr along with localized training
within the unidirectional flow aloft just ahead of the cold front.

Peak rainfall of another 1 to 2 inches is expected through 09Z
which may lead to areas of flooding or a worsening of any ongoing
flooding due to the saturated soils, especially within any low
lying areas or over largely impervious surfaces.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-ngB-HO2sGIIlbCwfzLASC4pp3xi7mBwZ1oGd1Ek782T68Z9SzH2GolVddsYLlXVgvIO=
2bQhKhOaZmmmLdfvVO7uURo$  for graphic product...

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

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

LAT...LON   35171178 35061128 34661062 34310996 33980980=20
            33640991 33221073 33271123 33511167 33641193=20
            33841279 34071310 34691326 34991308 35071287=20
            35151260 35161218=20

=3D =3D =3D
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