Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
237 PM EST Thu Jan 26 2023

Day 1
Valid 16Z Thu Jan 26 2023 - 12Z Fri Jan 27 2023

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Putnam


Day 2
Valid 12Z Fri Jan 27 2023 - 12Z Sat Jan 28 2023

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Putnam

Day 3
Valid 12Z Sat Jan 28 2023 - 12Z Sun Jan 29 2023

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

...2030 UTC Update...

General synoptic/mesoscale overview of the environment Saturday
night remains on track and consistent across the model guidance.
The 12Z guidance indicates the best potential for heavy rainfall
will be with the storms developing late Saturday night/early
Sunday morning across central Arkansas ahead of the surface cold
front pushing southward through the Middle/Lower Mississippi
Valley and Central/Southern Plains. Any instability will be
elevated and rather negligible keeping rain rates modest overall.
There will also be a narrow window early Sunday morning for heavy
rainfall with storms initiating in tandem with the development of
a coastal warm front along the southeastern Texas/southwestern
Louisiana Gulf Coast. However, as noted in the previous
discussion, it is likely that more impactful heavy rainfall from
these storms will be into the current day 4 period (12Z Sunday -
12Z Monday). Therefore, the risk remains Marginal across the
region.

Putnam

...Previous Discussion...

A shortwave impulse will break from an upper trough in the East
Pacific and propagate into the Southern Plains on Sunday night.
Surface low pressure will develop within an area of upper
divergence in southern Texas and lift into the Gulf Coast. This
new low pressure system will become the focus for heavy rainfall
and thunderstorms across the region beginning Sunday night and
continuing through early next week. Southerly mid-level flow
between 30-40kts will transport Gulf moisture, with PWATs between
1.5-1.75", into eastern Texas and the Gulf Coast. Another
shortwave and surface low pressure system propagating through the
midsection of the country will aid in pulling moisture northward
into the Ohio Valley and Northeast. Some of the latest guidance
suggests the potential for another QPF maxima to develop over
portions of the northern Arkansas, presumably due to the influence
of the northern stream shortwave and its surface fronts acting as
additional forcing and enhancement for precip.

The focus for Saturday's Marginal risk area will be over portions
of eastern Texas and the Lower Mississippi Valley. Soil moisture
is fairly high following recent heavy rainfall, but some drying
may occur before precip begins again on Sunday. The anticipated
recovery of soils and relatively high FFGs support the Marginal
risk area as drawn. Isolated instances of flash flooding are still
a possibility, especially along the Mississippi River where recent
flooding has caused those soils to be especially vulnerable.
Considering that the onset of heavy rainfall will be late Saturday
night, any slowing in future guidance may kick impacts of this
heavy rain threat into the following day (12z Sunday -- 12z
Monday).

Kebede


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