Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun May 28 2023 01:18:09

AWUS01 KWNH 280118
FFGMPD
MTZ000-IDZ000-ORZ000-WAZ000-280530-

Mesoscale Precipitation Discussion 0363
NWS Weather Prediction Center College Park MD
917 PM EDT Sat May 27 2023

Areas affected...Eastern WA...Northern ID...Northwest MT...Ext
Northeast OR...

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

Valid 280115Z - 280530Z

SUMMARY...Continued widely scattered downdrafts capable of intense
short-term rates (up to 1.5"/hr) across steep terrain pose highly
localized flash flooding risk through the early overnight period.

DISCUSSION...GOES-W Visible and 10.3um EIR imagery continue to
denote narrow overshooting tops breaking through the banded cirrus
canopy across Eastern Washington, northern Idaho and Northwest
Montana.   These cells are developing along/ahead of a
spoke/trough of the main upper low over north-central MT that is
rotating in from the north.  High anticyclonically curved
upper-level pattern continues to support broad area of divergence
centered over E WA/N ID, providing continued favorable broad scale
ascent.=20

Pockets of remaining surface heating are starting to dwindle but
the CAA aloft should maintain sufficient instability for these
cells through dusk into the early over night period.  Enhanced
moisture (with fairly humid low to mid-levels) are 2- 2.5 standard
anomalies above normal  has supported intense/efficient rainfall
production in these narrow but strong updrafts.  Strongest cores
have ample moisture (total Pwats of .75-1") should result in
1-1.25"/hr rain rates.  Combined with some additional low level
convergence along outflow boundary across the Columbia Plateau,
even stronger burst could be even more intense in shorter
sub-hourly duration.   Coverage/intensity should start to drop
after sunset with loss of surface heating.  Still highly
localized, widely-scattered incidents of flash flooding remain
possible, especially in steep terrain, burn scars or urban
centers.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!58frP0CNmNsM94umNPCjYfYjzkahsJocK0rfoE5YLTCjakchrQipGqlW39JQbzIprYsU=
ctkqOqV2LMrVJRBg6OFX9Rk$  for graphic product...

ATTN...WFO...MSO...OTX...PDT...

ATTN...RFC...NWRFC...NWC...

LAT...LON   49111723 49101557 48641435 47731347 47191314=20
            46411324 45861551 45611680 45121925 45942008=20
            46851997 47111911 47331810 47941771 48471855=20
            49061853=20

=3D =3D =3D
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