Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Jul 30 2025 02:49:08

AWUS01 KWNH 300248
FFGMPD
NEZ000-SDZ000-MTZ000-WYZ000-300845-

Mesoscale Precipitation Discussion 0828
NWS Weather Prediction Center College Park MD
1047 PM EDT Tue Jul 29 2025

Areas affected...Far Southeast MT...Northeast
WY...Western/Southern SD

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

Valid 300247Z - 300845Z

SUMMARY...Organizing clusters of heavy showers and thunderstorms
will pose concerns for isolated to scattered areas of flash
flooding heading into the overnight hours.

DISCUSSION...The evening GOES-W IR satellite imagery along with
radar shows expanding clusters of well-organized showers and
thunderstorms impacting far southeast MT down through northeast
WY. This activity is expected to interact favorably with a moist
and unstable airmass pooled across the High Plains for upscale
growth of convection, and likely an MCS, going into the overnight
hours which advance down across areas of western and southern SD.

MLCAPE values of 1000 to 1500 J/kg are in place along the WY/SD
border, with effective bulk shear of 30 to 40+ kts. This coupled
with the moist easterly flow should favor rather organized
convection capable of producing rainfall rates of 1 to 2
inches/hour.

The latest RAP analysis shows a corridor of stronger moisture
convergence pooled across far southeast MT and into northeast WY
where some of the stronger ongoing convective cells are noted, but
there should be an axis of strengthening moisture convergence
overnight across areas of western and southern SD which support
eventually a threat of organized convection impacting portions of
these areas.

The 18Z HREF and recent HRRR guidance suggests some rainfall
totals may reach 2 to 4 inches over the next 6 hours as this
overall convective footprint grows in scale and matures overnight.
Given rather dry antecedent conditions overall, these rains will
support generally isolated to perhaps scattered concerns for flash
flooding and primarily where any cell-mergers or brief
cell-training concerns set up.

Orrison

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_Qgq2g1V2cAg2ZAHRjeL2GKaVj9UvQDIhBhlKUU9doC4cIgxullpL9607HGeCLyOBnT7=
1oxp3iXcab-2zZ8d6dLvSo4$  for graphic product...

ATTN...WFO...ABR...BYZ...CYS...FSD...LBF...RIW...UNR...

ATTN...RFC...KRF...NWC...

LAT...LON   45850431 45610345 45200235 44780082 44319772=20
            43359741 42929847 42850063 42930326 43140496=20
            43720695 44770740 45510680 45790581=20

=3D =3D =3D
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