BBS: TELESC.NET.BR
Assunto: MESO: Nws Weather Prediction Center College Park Md
De: COD Weather Processor
Data: Fri, 17 Apr 2026 18:11:42 +0000
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AWUS01 KWNH 171811
FFGMPD
WIZ000-ILZ000-MOZ000-MNZ000-IAZ000-180010-
Mesoscale Precipitation Discussion 0115
NWS Weather Prediction Center College Park MD
210 PM EDT Fri Apr 17 2026
Areas affected...Northeast MO...Western and Northern IL..Eastern
IA...Far Southeast MN...Central and Southern WI
Concerning...Heavy rainfall...Flash flooding likely
Valid 171810Z - 180010Z
SUMMARY...Rapid convective development is expected over highly
saturated soils this afternoon. Anomalous moisture and instability
will support rainfall rates of 1 to 2 inches/hour. While
individual cell motions will be fast, cell-training will lead to
localized totals of 2 to 4 inches, making flash flooding likely
given the sensitive antecedent conditions.
DISCUSSION...GOES-E Day Cloud Phase RGB satellite imagery and
surface observations indicate rapid destabilization across the
Upper Midwest ahead of an ejecting upper-level trough and
approaching strong cold front. A 40 to 50+ kt southwesterly
low-level jet is fostering intense warm air advection and moisture
transport into the region, resulting in an anomalously moist and
unstable airmass for mid-April (PWATs climbing to ~1.25 inches and
MLCAPE of 1500 to 3000 J/kg).
Convective initiation is expected imminently as the cap erodes,
particularly near surface waves analyzed over north-central IA and
southeast MN which are locally enhancing convergence. Deep-layer
ascent will continue to increase this afternoon and evening as a
strong shortwave/jet streak rounds the base of the trough and
approaches from the west. Convective mode is expected to feature a
mix of supercells and organized multicell clusters.
While strong deep-layer shear (40 to 50+ kts) will promote fast
individual cell motions to the northeast, the southwesterly
steering flow is largely parallel to the low-level jet axis and
lifting warm front. This alignment will strongly favor corridors
of cell-training and repeating rounds of heavy rainfall over the
same areas. High-efficiency updrafts will be capable of producing
1 to 2 inch/hour rainfall rates, with the 12Z HREF signaling
localized swaths of 2 to 4 inches through 00Z.
The primary driver for the flash flood threat is the highly
sensitive antecedent conditions. Recent NASA SPoRT 0 to 10 cm soil
moisture data indicates very moist if not saturated soils (80 to
100%) across much of the region, and USGS streamflow networks show
running waterways are already elevated. With minimal infiltration
capacity, the intense 1 to 2 inch/hour rates will to convert to
enhanced runoff concerns, and likely promoting scattered areas of
flash flooding which will include some localized urban impacts as
well.
Orrison
...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!9hjs2Z_oHmyo18eoaSQu7i3KoZD9Delq5_o_Aeyu83kiVMQIawM1h87TuD-4LEItpLhN=
MhaDX-LNgGe5ulc54SN8dxk$ for graphic product...
ATTN...WFO...ARX...DLH...DMX...DVN...EAX...GRB...ILX...LOT...
LSX...MKX...MPX...
ATTN...RFC...KRF...MSR...NWC...
LAT...LON 45659058 45318891 44168851 42578857 41148902=20
40108946 39429028 39319154 39769277 40559338=20
41339334 43079263 44399214 45129163=20
=3D =3D =3D
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