Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Jan 01 2023 08:24:47

FOUS30 KWBC 010824
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
323 AM EST Sun Jan 01 2023

Day 1
Valid 01Z Sun Jan 01 2023 - 12Z Sun Jan 01 2023

....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
CENTRAL AND SOUTHERN ARIZONA...

A progressive atmospheric river (AR) and associated jet streak
will move eastward across AZ this New Year's Day. The
unidirectional flow and highly anomalous Pacific moisture with
PWATs up to 1 inch, or +3 sigma will support continued heavy rain
through the atmospheric river moisture plume into Arizona. This
heavy rain will be offset somewhat by the fast forward/eastward
motion of the AR. Thus, only a few hours of heavy rain is forecast
for any one location in AZ through the day today. Following behind
the main area of rain, falling snow levels and much lighter
precipitation will quickly end the flooding threat. Thus, the
focus for flooding rains will quickly shift east through the day
and will largely end by tonight, so the Marginal Risk is really
for the first 12-15 hours or so of the forecast period. Further,
once the moisture plume gets to NM, it will largely be cut off
from the Pacific as the flow becomes nearly due southerly,
resulting in rapid weakening of any associated convection.
Rainfall rates between 0.5 and 0.75 inches/hour are possible
during this time, but the main concern for isolated flash flooding
will be in burn scars, slot canyons, and any urbanized or other
typically sensitive areas. Very few changes in the guidance were
noted, particularly associated with the falling snow levels behind
the cold front/AR. There were no changes made to the inherited
Marginal Risk area for this forecast update.

Wegman


Day 2

The Day 2 outlook will be updated by 0830Z.


Day 3

The Day 3 outlook will be updated by 0830Z.


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!-IVh8SMuWzMhJ5iUrz4LyV1irjbxt7eWgDTwV2xCxZf7=
P1C8_LUCbNw_6ZXuZtHZ4vf1rwThsfF042x7yM2HQ_Hd3pc$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!-IVh8SMuWzMhJ5iUrz4LyV1irjbxt7eWgDTwV2xCxZf7=
P1C8_LUCbNw_6ZXuZtHZ4vf1rwThsfF042x7yM2H2oNGFC4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!-IVh8SMuWzMhJ5iUrz4LyV1irjbxt7eWgDTwV2xCxZf7=
P1C8_LUCbNw_6ZXuZtHZ4vf1rwThsfF042x7yM2H9Izcr8E$=20


$$



=3D =3D =3D
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