Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Jul 19 2023 20:41:50

AWUS01 KWNH 192041
FFGMPD
MNZ000-200200-

Mesoscale Precipitation Discussion 0765
NWS Weather Prediction Center College Park MD
441 PM EDT Wed Jul 19 2023

Areas affected...Northern Minnesota...

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

Valid 192040Z - 200200Z

SUMMARY...Multiple slow moving or repeating cells within the
TROWAL ahead of digging shortwave trough pose possible localized
flash flooding problem into this evening.

DISCUSSION...Regional RADAR and GOES-E Visible loop depict
organizing band of stronger elevated thunderstorms across the
Northwest Angle into north-central MN.  WV suite denotes main
upper level low is sliding southeast across ND resulting in a weak
col in mid-level flow/pivot across this region resulting in slow
cell motions, while concurrently allowing for enhanced trapped
moisture to increase along the TROWAL.  Moisture is fairly limited
through depth allowing for stronger severe signals with hail
generation at this time, but is slowly transitioning with a
moistening deeper profile toward moist adiabatic but at the same
time remaining weakly to modestly unstable.  As such,
thunderstorms will start increasing to about 1.5"/hr and given
slow motions may allow for localized 2-3" totals.  Recent
back-yard observation of 1.55" in 1hr near Baudette provides
confidence toward this level of rainfall efficiency.   HREF
signals of 40-50% of 2"/3hr very near the surface low at the apex
of the TROWAL in Lake of the Woods county decrease but show an
axis into N Itasca county.  Southward, deeper westerly flow and
stronger height-falls from the approaching deeper layer trof, will
allow for increasing forward propagation, so unless there are
back-building or flanking line cells training, the risk for flash
flooding sizably decreases across northeast MN (nearer the warm
front).

Hydrologically, the grounds are very dry with FFG values at or
above these 2-3" values.  However, the intensity of the rainfall
in short-duration upon harder hydrophobic ground conditions may
limit infiltration and result in increased runoff locally.  As
such flash flooding is considered possible, particularly if
upstream cells track across the same areas when the upper-level
trough kicks eastward into the area.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_atgvJdB1AvfZ49pm75xdyRUAr1y4gkpvrgmAmzqWgNmAKhOmdbH83sSNSlytvCKasC2=
PcoqOs6QGyGdu5_mEUy9Aok$  for graphic product...

ATTN...WFO...DLH...FGF...

ATTN...RFC...NCRFC...NWC...

LAT...LON   49419519 49369461 48829436 48659303 48549256=20
            48179145 47629150 47239199 47309345 47539491=20
            47749618 48139650 48749633 49019565 49069526=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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