Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Aug 18 2023 07:51:27

FOUS30 KWBC 180751
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
350 AM EDT Fri Aug 18 2023

Day 1
Valid 12Z Fri Aug 18 2023 - 12Z Sat Aug 19 2023

....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
NORTHWEST ARIZONA INTO SOUTHWEST UTAH...

Northeast...=20
A Marginal Risk remains across the region.  Heavy rain may be
ongoing at 12z Friday (a continuation of the previous day's
rainfall)...with another round possible during the day Friday as
destabilization occurs ahead of the approaching trough/closed low.
 The timing of the trough and how it interacts with the
moisture/instability streaming up the coast will play a role in
the magnitude of the eventual flash flood risk.  As the guidance
amounts still appear modest, on the order of 1-2", some portions
of the area have been wet this past week.  Can't rule out an
upgrade to Slight Risk at some point should the signal in the
guidance increase.=20
=20=20
=20
Portions of the West...=20
A Slight risk remains across northwest AZ into southwest UT, with
some expansion into far southern NV and western AZ.  Seeing a
notable uptick in mid/upper level forcing by this time as the
closed low off the CA coast shifts eastward and the upper jet west
of the area intensifies.  The precipitable water values in the
monsoon surge up the Gulf of California are increasing this period
with values perhaps breaching 2" by early Saturday morning and
~1000 J/KG of ML CAPE is expected during Friday afternoon and
early evening.  Enough moisture and instability around to support
heavy rainfall rates, up to 2" where cells merge, backbuild, or
manage to train.  This would be a problem over the susceptible
areas of southern NV, western AZ, and southwest UT.=20=20
=20=20
=20
Florida...=20
A Marginal risk over portions of central/southern FL.  The
moisture plume from the polar front gets entangled with an
incoming easterly wave that is moving through the Bahamas.  Flow
should be becoming more easterly, though remaining light, so there
is concern about slow moving cells, and with the incoming easterly
wave, increasing amounts of effective bulk shear which could lead
to some loose organization.  The thinking is that outflow
boundaries will shift activity enough to prevent overwhelming
amounts, but hourly rain totals to 2.5" with local amounts to 5"
cannot be ruled out.  Since Central FL in particular has been so
dry lately, kept the risk level as Marginal.=20
=20=20
Roth=20


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!5RzLnsGlI7VQZ_YPGA9JxXY5dShlxDZ8yB7nAUkxIpzk=
Yp-Q5co9A-QpA-nxADtLNCyRZr1HUE7qHb2v7macr_jdCJ8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!5RzLnsGlI7VQZ_YPGA9JxXY5dShlxDZ8yB7nAUkxIpzk=
Yp-Q5co9A-QpA-nxADtLNCyRZr1HUE7qHb2v7macqoOdCPM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!5RzLnsGlI7VQZ_YPGA9JxXY5dShlxDZ8yB7nAUkxIpzk=
Yp-Q5co9A-QpA-nxADtLNCyRZr1HUE7qHb2v7maclV_gRa0$=20


$$



=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to
https://lists.illinois.edu and use the "Unsubscribe" link.  Otherwise email
Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.14-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

.