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FOUS30 KWBC 260151
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
951 PM EDT Tue Jun 25 2024

Day 1
Valid 01Z Wed Jun 26 2024 - 12Z Wed Jun 26 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
MIDWEST...

01Z update... Excessive rainfall outlook graphics are able to get
onto the WPC website, but the discussions are not able to due to
ongoing comms issues.

...Plains...Midwest...Mid-South...

Redevelopment of scattered storms along a line from the Sandhills
of Neb through southern IA into north-central IL continues this
evening. Locally heavy rainfall with rates exceeding 1"/hr can be
expected as this activity shifts southeast. The Slight Risk is
maintained for northern Missouri.

Further development over the southern Plains in OK and
the TX Panhandle will continue working south. The Slight Risk was
expanded south over the rest of Missouri and the Marginals were
expanded to the TX Panhandle and through the Ozarks of Arkansas.

Activity farther east has diminished, so the Marginals were removed
from Michigan and all but western Indiana. The 00Z HRRR was helpful
with ERO extension updates.


...Southwest...
PW values will remain highly anomalous (above the 95th
climatological percentile and +5 standard deviations) from southern
California into the Great Basin with a continuation of weak
forcing under the upper ridge axis stretching from the
Southern/Central Plains into the Southwest. An influx of deeper
moisture throughout the mid-levels is associated with a tropical
disturbance over Mexico. This added moisture and sufficient
instability should allow convection to continue through and
evening hours with the Marginal Risk maintained across the broad
region of the Southwest and Four Corners.


Jackson

Day 2
Valid 12Z Thu Jun 27 2024 - 12Z Fri Jun 28 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE NEW MEXICO...

...Southwest...

21Z update... Due to ongoing severe comms issues graphics and other
data are largely unable to update. The latest guidance continues to
focus some of the highest QPF across central New Mexico, with amounts
of 0.50 to 1 inch possible. This part of the state has a Slight risk
in effect (albeit an old graphic) and that still matches the level
ofrisk for localized flooding potential. Isolated to scattered
thunderstorms are expected across the Four Corners,
Southern/Central Rockies and into the Central High Plains. Guidance
is suggesting areal averages of 1 to 2 inches for portions of
western Nebraska and Kansas. FFG over this part of the country is a
still higher than over the Southwest however these storms may have
the potential for higher rainfall rates that could reach or exceed
FFG in isolated locations. A Marginal Risk covers much of the Four
Corners to the Central High Plains area.

Campbell

No significant large scale changes expected during this period over the
Southwest besides the gradual northward lifting of anomalous PWs into
parts of UT. PW values 3-4+ standard deviations above the mean will
persist from southern California, into the Southwest and southern Great
Basin in a region of continued weak forcing under the building closed
high over the Southwest. Widespread scattered diurnal convection again
possible across these areas, with continued low confidence in any qpf
details. There is some elevated concern that convection could be widespread
enough to create scattered flash flooding throughout the slot canyon
region of south-central Utah. This area will likely be monitored for
a targeted upgrade over the next few days should sufficient instability
show up in CAMs and greater qpf coverage.

...Lower Mississippi Valley to the Northeast...

21Z update... Due to ongoing severe comms issues graphics and other
data are largely unable to update. During this period showers and thunderstorms
are expected to develop along and ahead of the front moving through
the Great Lakes, Midwest and Mississippi Valley. With the west-east
orientation of the front along with anomalous PW pooled over the region,
training of thunderstorms with potential for moderate to heavy downpours
can be expected across portions of the Midwest, Lower Great Lakes and
into parts of the Northeast. This is where some of the highest QPF amounts
are expected to focus. A Marginal Risk is in effect (albeit an old graphic)
from the Lower Mississippi Valley/Central Gulf Coast to the Northeast.
The continues to reflect the level of threat for excessive rainfall
and flooding concerns at this time.


Campbell

In the wake of the warm front pressing northeastward across the Upper
Mississippi Valley/Upper Lakes region, the associated cold front will
be dropping southeast from the Northern Plains into the Upper Mississippi
Valley/Upper Lakes during this period. Additional convection likely
to develop in the axis of high PWs pooling along the front that becomes
more west to east oriented. Convection may train in a west to east direction
parallel to this front as the low level flow will also be westerly along
and ahead of the boundary. There still is spread in model qpf details,
but the multi model ensemble qpf mean and latest NBM do show potential
for heavy amounts across areas of far southern WI/eastern IA and northern
IL that have received heavy rainfall recently. A broad marginal risk
spans from the central Gulf Coast, portions of the Tennessee/Ohio Valleys
and most of the Northeast.

Snell/Oravec

Day 3
Valid 12Z Thu Jun 27 2024 - 12Z Fri Jun 28 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE NORTHERN AND CENTRAL PLAINS AND FOR PORTIONS OF NEW MEXICO,
COLORADO AND FAR SOUTHERN WYOMING...


21Z update... Due to ongoing severe comms issues graphics and other
data are largely unable to update. Moderate to heavy showers are expected
in the vicinity of the Central Rockies and south to north- central New
Mexico. A Slight Risk is in effect for this part of the region. Over
the Plains, another area of concentration of heavy rain will be over
eastern Kansas/Nebraska and much of Iowa. This part of the country has
had recent rains to bring soils to near saturation. An additional 1
to 3 inches over this region may lead to areas of isolated to scattered
flash flooding therefore a Slight Risk is in place. Moderate to heavy
showers will also be tracking near the International border where recent
rains have kept soils moisture above average. Additional rain from far
northeast Montana to northwest Minnesota may lead to scattered areas
of flooding, a Slight Risk remains in effect.

Campbell

A low pressure system and associated fronts tracking into the Northern
Plains Thursday will bring a threat for heavy rainfall across the north-
central Plains into the Upper Midwest. Some conflicting signals remain
regarding locations that may see significant rainfall, but latest guidance
is suggesting two areas of relatively greater focus during the
period. One is within the existing Slight Risk area over parts of the
Midwest with a modest southwestward adjustment per latest guidance, and
another farther north across northern North Dakota and far northwestern
Minnesota where a Slight Risk area has been introduced. Slight Risk
areas within the broader Marginal Risk are subject to change based on
updated forecasts of convective evolution and location relative to areas
with greatest sensitivity due to prior heavy rainfall.

Santorelli


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