Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Jun 10 2023 15:07:34

AWUS01 KWNH 101507
FFGMPD
MTZ000-WYZ000-102001-

Mesoscale Precipitation Discussion 0456
NWS Weather Prediction Center College Park MD
1107 AM EDT Sat Jun 10 2023

Areas affected...Southern MT...Northern WY

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

Valid 101506Z - 102001Z

SUMMARY...Slow moving heavy thunderstorms containing excessive
rainfall rates as high as 2"/hr may lead to additional flash
flooding, especially in areas with sensitive soils.

DISCUSSION...GOES-16 satellite imagery showed a cluster of strong
thunderstorms over southeast MT that were showcasing plenty of
lightning strikes on the satellite's GLM. These storms have taken
advantage of both an approaching cold front and easterly 850-700mb
mean flow to prompt strong ascent within the atmospheric column to
enhance convection. These storms have formed in an environment
sufficient for efficient rainfall producing storms. This includes
the following: PWs close to 1" (in the 97.5-99.5% climatological
percentile according to NAEFS), MLCAPE between 250-500 J/kg, and
mean low-mid RH values that are between 85-90% in some cases. The
unusually saturated low levels and freezing levels just below
9,000' have led to warm cloud layers as much as 4,000-6,000' deep.

When combined with the regions overly saturated soils (AHPS 7-14
day rainfall totals are 400-600% of normal), this is a opportune
setup for additional flash flooding. The front will continue to
press south, as will the field of easterly winds that are
supporting upslope enhancement into ranges such as the Bighorns.
1-Hr FFGS are <1.0" in parts of the highlighted region, and MRMS
multi-sensor 1-hr amounts east of Billings had approached 2". This
suggest any additional storms could see rainfall rates more
commonly closer to 1", but could approach 2"/hr in the more
intense thunderstorm activity. Additional flash flooding is
possible through midday, especially in areas with sensitive soils,
in nearby creeks and streams, and along complex terrain.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!4dSS56AfJwVRPsjtl1k7ig1BOagvSNQxjZosO85nxz6g2VN8MnKoopabD55vh4rPD0fg=
8Qe3O3Hcjv2UhwevapB1iQ4$  for graphic product...

ATTN...WFO...BYZ...RIW...

ATTN...RFC...MBRFC...NWC...

LAT...LON   46660902 46490769 45190636 43680617 42950645=20
            43040711 43600773 44330834 44810904 45310984=20
            46161007=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)

.