Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon May 29 2023 21:58:25

AWUS01 KWNH 292158
FFGMPD
WYZ000-UTZ000-IDZ000-NVZ000-300300-

Mesoscale Precipitation Discussion 0381
NWS Weather Prediction Center College Park MD
557 PM EDT Mon May 29 2023

Areas affected...Northeast NV...Southern & Southeast ID... Far
Northwest UT...Central TWestern WY...

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

Valid 292200Z - 300300Z

SUMMARY...Enhanced moisture/instability pooled along shear axis
with favorable steering flow for repeating thunderstorms pose
possible scattered incidents of flash flooding this
afternoon/evening.

DISCUSSION...GOES-E WV suite depicts an elongated mid-level shear
axis stretching from the closed low west of central CA to the
exiting northern stream trof over North Dakota.  This shear axis
extends from N NV across the Basin/Range topography of southern ID
into west-central WY.  Weak vortex roll up appears possible along
this axis resulting in wavy packet of DPVA along its length.  Deep
layer moisture is also enhanced across this zone with total Pwats
of .75 which is generally in the 95th percentile and about 1.5-2"
standard deviations from normal.  Solid morning insolation also
resulted in ample heating, with RAP analysis depicting 1000-1500
J/kg from NE NV across S ID, with a pocket of 2000 J/kg in NE NV.=20

Given available buoyancy and upper-level DPVA forcing support,
numerous thunderstorms have developed along the length of the
instability axis.  Cores are modestly sized but given localized
inflow, flux supports .75-1"/hr rates.  Deep layer flow is
unidirectional due to the shear axis, but given the displacement
from the stronger waves, winds are weaker allowing for 10-15kts of
forward speed, but highly favorable for repeating cells.  So
scattered localized 1" totals are possible.  While, outflow is
likely to be modest, propagation into the Snake River Plain is
possible, though the deep layer steering and overall coverage
should allow for some repeating/training potential through the
evening hours; perhaps resulting in spot totals up to 1.5".=20=20
While, FFG may not be as reliable in these dry deserts/alternating
high terrain, these hourly rates/totals are well above inducing
localized flash flooding and given the overall coverage of
thunderstorms already, flash flooding is considered possible.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5BZUpVQ72UplBSdvjnvwmet6uvlJL8Rfqf13TGtEByC5SPktVCpgA15_xfh1VvSnm_HI=
nCzO8j48xJ7GfE_PTvZOY1k$  for graphic product...

ATTN...WFO...BOI...LKN...PIH...RIW...SLC...

ATTN...RFC...CBRFC...CNRFC...NWRFC...NWC...

LAT...LON   43821102 43631037 42911009 42421065 41751299=20
            41381436 41051579 41131662 42061653 42501530=20
            43421224=20

=3D =3D =3D
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