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000
FOUS30 KWBC 180817
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
417 AM EDT Thu Apr 18 2024

Day 1
Valid 01Z Thu Apr 18 2024 - 12Z Thu Apr 18 2024

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

A cold front will be advancing south and east through the Central
and Southern Plains while a warm front lifts through the Mid-
Mississippi and Tennessee Valleys. A broad area of showers will
spread along and north of the warm front from Missouri to northwest
Georgia. Meanwhile storms will fire up ahead of the approaching
cold front from Missouri to Texas. The Gulf moisture streaming
northward will help enhance and sustain rainfall across the region
and may become heavy at times. Recent rains have lowered some of
the FFG across this region and may have an increased sensitivity to
additional rain/heavy rain. A Marginal Risk area covers part of
northeast Texas to southern Missouri and western Kentucky. The
latest guidance is persistent with rainfall rates of 1-2 inches
across eastern Missouri, southern Illinois, and western Kentucky.

Regional instability is highest across the southern plains, but
the combination of stronger mid-level forcing along with sufficient
buoyancy is located over the Mid- Mississippi Valley where the
best prospect for flooding is anticipated. Relative progressive
nature of the cold front will limit higher end potential over the
Missouri Basin, but an upgrade to a Slight is not completely out of
the question, pending evolution and trends upstream as the
shortwave exits out of Nebraska.

Campbell/Kleebauer


Day 2
Valid 12Z Thu Apr 18 2024 - 12Z Fri Apr 19 2024

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE TEXAS BIG BEND AND WEST TEXAS AND FOR PARTS OF THE RED RIVER...

The cold front will continue to press southward through the
Southern Plains and Lower Mississippi Valley before
slowing/stalling. A dryline will also be present from the Oklahoma
Panhandle to the Big Bend area. Convection is expected to be along
and south of the front over the Southern/Central Plains and Lower
Mississippi Valley with the higher QPF near/east of the dryline in
west-central Texas.

The consensus for the area over the Texas Big Bend up through the
Edwards Plateau has grown within this suite of guidance with the
environment primed for higher end convective development from the
Lower Trans Pecos, eastward into the Rio Grande and adjacent
Edwards Plateau. Ensemble probabilities remain on the lower end,
however they are within the 10-20% range for totals exceeding 2"
which would be sufficient for localized flood concerns within the
terrain focused over the area.

The timing differences remain across the Red River and southern
Oklahoma with the front into that area with the convergence
pattern expected towards the back end of the forecast period with a
higher potential for flash flooding. A Marginal Risk area spans
the Big Bend area northeast into the Edwards Plateau and Concho
Valley. Another Marginal Risk area covers portions of southern
Oklahoma, northeast Texas and western Arkansas.

Campbell/Kleebauer


Day 3
Valid 12Z Fri Apr 19 2024 - 12Z Sat Apr 20 2024

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR EASTERN TEXAS,
NORTHWEST Louisiana, SOUTHWEST ARKANSAS AND EXTREME SOUTHERN
OKLAHOMA...

The front will remain stalled across the South meanwhile moisture
will steadily increase. Precipitable water values of 1 to 1.5
inches (upwards of 2.5 sigma) will be in place across much of the
Southern Plains and Lower Mississippi Valley also where there will
be very strong mid-level ascent. This environment will be very
conducive for widespread heavy rainfall. The highest QPF will focus
over central and eastern Texas where areal averages of 2 to 4
inches will be common - a Slight Risk area covers much of this part
of region. Isolated higher amounts will possible, particularly for
locations east/northeast of the Hill Country. A Marginal Risk area
spans from western TExas to eastern Mississippi.

Campbell


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