FOUS30 KWBC 300822
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
422 AM EDT Wed Oct 30 2024

Day 1
Valid 12Z Wed Oct 30 2024 - 12Z Thu Oct 31 2024

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FROM THE
SOUTHERN PLAINS TO THE UPPER MISSISSIPPI VALLEY/UPPER MIDWEST...
 
Convection over the region is expected to increase in both 
coverage and intensity with the set up becoming more favorable for 
isolated heavy rainfall amounts/rates and localized flooding 
concern. Showers and thunderstorms in the vicinity to Oklahoma, 
Texas and Arkansas state borders will have local enhancement amid 
areas of higher instability. There has been a persistent westward 
shift from run-to run guidance in regards to the placement of the 
higher QPF across the Plains and Upper Mississippi Valley/Upper 
Midwest, but general consensus is favoring a concentration across 
north- central Iowa into southeast Minnesota and western Wisconsin 
where the greatest height falls are located and fastest 
acceleration of low level flow. This will enhance local rainfall 
efficiency and boost amounts. Deterministic guidance suggests 1 to
3+ inches across this area. 

Antecedent conditions are quite dry- as reflected by the very high
flash flood guidance. That should mitigate any widespread threat 
of excessive rainfall as well as progressive cells. Even so, the 
Marginal Risk area still seemed appropriate based on what the 
magnitude of the instability and mesoscale forcing from the coarser
numerical guidance with room to adjust with future guidance 
(including the CAM guidance).

Campbell/Bann


Day 2
Valid 12Z Thu Oct 31 2024 - 12Z Fri Nov 01 2024

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE LOWER MISSISSIPPI VALLEY...

As the upper level trough advances through the Upper Midwest the
surface front will makes its way into the Southern Plains and Mid-
Mississippi Valley. Instability is expected to remain the highest 
in portions of the Lower Mississippi Valley while the flow 
pattern/mesoscale forcing weakens farther north. Convection is
expected to initiate along and ahead of the cold front by late
morning and increase coverage during the afternoon hours across the
Lower Mississippi Valley and into the Lower Ohio Valley. Areal 
averages will be in the 1 to 2 inch range with locally higher 
amounts possible.

Campbell


Day 3
Valid 12Z Fri Nov 1 2024 - 12Z Sat Nov 02 2024

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN ROCKIES AND SOUTHERN PLAINS...

Another trough will move inland across the West as ridging stays in
place over much of the South. Warm Gulf moisture will be advecting
northward through the High Plains. Meanwhile, the strongest
instability will likely be in place over West Texas and eastern new
Mexico. Areal coverage of thunderstorms is forecast to increase
during the overnight hours into portions of the Texas panhandle,
Oklahoma and far southern Kansas. Per SPC, the environment will be
conducive for large hail and there is a Marginal Risk in effect for
severe weather. There is also the potential for excessive rainfall
near eastern new Mexico and West Texas/Panhandle and there is a
Marginal Risk area in effect for the threat of isolated areas of
flooding.

Campbell

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