Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Sep 09 2025 00:16:11

AWUS01 KWNH 090016
FFGMPD
CAZ000-ORZ000-090415-

Mesoscale Precipitation Discussion 1065
NWS Weather Prediction Center College Park MD
815 PM EDT Mon Sep 08 2025

Areas affected...southwestern/western OR

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

Valid 090011Z - 090415Z

SUMMARY...Scattered thunderstorms with repeating and brief
training could result in an inch or two of rainfall with rainfall
rates of 1 inch in an hour or less for portions of
southwestern/western OR. Isolated flash flooding could result,
with a particular focus across burn scars.

DISCUSSION...Visible satellite imagery from GOES West at 00Z
showed the low to mid-level reflection of a closed low west of the
northern CA coast containing a number of smaller scale vorticity
maxima rotating about the low center. In addition, another
vorticity max was located inland, over northern Douglas County in
southwestern OR, moving toward the north. Scattered thunderstorms
were observed through radar/satellite imagery along and just west
of the Cascades and across portions of the Klamath Mountains of
southwestern OR. While PW values were anomalous for early
September (+2 to +3 standardized anomalies), instability was
somewhat limited with pockets of 500-1000 J/kg in place over the
region via 00Z SPC mesoanalysis data.

Deeper layer mean flow was from the south at 10-20 kt, similar to
the low level inflow layer, which was favoring repeating and brief
training of cells in a few locations. While the threat appears
isolated, there will be the potential for cells to generate
rainfall of an inch within 60 minutes or less time. These
localized higher rainfall rates could overlap with sensitive
terrain or burn scars to result in isolated flash flooding. The
flash flood threat is likely to diminish with the loss of daytime
heating and reduction in instability after 04Z.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7juXn12P2XvRjw5FO_GiHYeSjFptrhuUgWfLJv-2sRn91Z9VJotsm0KMG112qxLtbxTy=
usJC8UcW58nvem7eaCrT9L0$  for graphic product...

ATTN...WFO...EKA...MFR...PDT...PQR...

ATTN...RFC...PTR...RSA...NWC...

LAT...LON   44692233 44472206 43982189 43262205 42732214=20
            42252228 42022261 41922316 41982373 42242393=20
            43162394 44052370 44692285=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 3.28-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

.