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FOUS30 KWBC 070815
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
415 AM EDT Fri Jun 7 2024

Day 1
Valid 12Z Fri Jun 07 2024 - 12Z Sat Jun 08 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL PLAINS...

The setup continues to look favorable for a heavy rainfall event
across portions of the Central Plains later today through tonight.
Early morning analysis showed a strong ridge of high pressure
anchored over the Four Corners into Texas while over the Central
Plains, northwest flow is present. Across the Northern Rockies,
shortwave trough energy is noted and it`s this feature that will
dive southeast into the Plains later today to help ignite a few
rounds of deep convection. In the lower levels, southerly flow in
response will bring northward anomalous moisture with the PWs
forecast to quickly rise above 1.5" through KS into southern NE.
The favorable forcing aloft with the higher moisture and expected
instability will ignite the storms and then the expectation is for
the storms to grow upscale into a MCS as it moves into portions of
Missouri and clip southwest Iowa.

The 00Z guidance has come into better agreement on the details and
expected locations of the heavy rainfall, with the 00Z HREF
neighborhood probabilities for at least 3 inches jumping to above
50 percent now for far eastern NE, northeast KS, southwest IA, and
northwest MO with a slight (10-15 percent) chance of 5" totals.
Hourly rain totals may exceed 2 inches in localized spots. The
Slight Risk was adjusted minimally to the north, to adjust toward
the latest guidance and probabilities where the setup for
training/repeating rounds is greatest.

Taylor


Day 2
Valid 12Z Sat Jun 08 2024 - 12Z Sun Jun 09 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
EASTERN KANSAS THROUGH SOUTHERN MISSOURI...

The latest guidance continues to advertise a corridor of heavy
rainfall across portions of the Southern/Central Plains eastward
into the Mid Mississippi Valley as a cold front sags southward into
the region and low level southerly flow pushes anomalous moisture
into the boundary. Aloft, the quasi zonal flow along with an
embedded shortwave trough moving through will help bring the larger
scale forcing. This combination of higher moisture (PWs 1.5-2") and
lift along with favorable amounts of instability forecast should
support multiple rounds of thunderstorms, particularly from the
late afternoon through the nighttime hours. The latest ensemble
guidance members and deterministic models support potential for
localized 2-3" totals and rain rates 1-2"/hr at times with the
greatest potential for those higher totals over far eastern KS
through southern Missouri where the Slight Risk is highlighted.

Further west, moisture banking against the terrain of the Front
Range combined with daytime peak heating and shortwave trough
energy moving through will lead to isolated/scattered showers and
thunderstorms, some of which will be slower moving and produce
intense rain rates and isolated/localized flash flooding.

Taylor


Day 3
Valid 12Z Sun Jun 09 2024 - 12Z Mon Jun 10 2024

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF COLORADO FRONT RANGE, SOUTHERN PLAINS, AND MID MISSISSIPPI
VALLEY...

The wavy, slow moving frontal boundary is expected to reach
portions of the Southern Plains and Mid Mississippi Valley Sunday
through early Monday morning while aloft the pattern is expected to
feature quasi zonal/northwest flow. An embedded shortwave trough is
forecast to move through the region during the period, providing
the large scale forcing for ascent. Meanwhile, higher moisture
characterized by PWs > 1.5" will pool along/ahead of the surface
boundary across the S. Plains into the Mid Mississippi Valley. This
anomalous moisture, combined with the southward moving frontal
boundary and large scale lift will support thunderstorm
development early on in the period across portions of KS/MO/AR
before the focus for new development shifts westward toward the TX
Panhandle, western/central Oklahoma. The latest guidance supports
isolated/scattered 1-2" totals (based off latest ECENS/GEFS
members) and embedded higher amounts possible, especially across
TX/OK where the deeper moisture overlaps best with the instability
and forcing.

The easterly flow will also bank the higher moisture against the
terrain and lead to thunderstorm development from eastern New
Mexico through the CO Front Range where slow storm motions and/or
repeating rounds may lead to localized but intense rain
rates/totals late in the period (00Z-12Z Mon).

Taylor

Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt