Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Thu Jul 3 2025
Day 1
Valid 12Z Thu Jul 03 2025 - 12Z Fri Jul 04 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS WESTERN
PORTIONS OF THE FLORIDA PENINSULA, WEST TEXAS, AND NEW MEXICO...

...Southwest to the Southern Plains...
A mid-to-upper level shortwave moving into southern California
this morning will move into the Four Corners region by this evening
and then the central and southern Rockies overnight. The large
scale lift associated with the wave, along with ample moisture
remaining in place, are expected to produce widespread showers and
thunderstorms across Arizona and New Mexico. A Slight Risk was
maintained across the eastern New Mexico and West Texas mountains
into the High Plains, where additional storms are expected to
develop across the same areas that have received several rounds of
storms and periods of flash flooding over the past several days. A
Marginal Risk was maintained farther to the north into the central
Rockies, extending into parts of southern Wyoming, where the
overnight guidance continues to indicate the potential for
localized heavy amounts as the deeper moisture is drawn northward
ahead of the advancing shortwave.

While differing in the details, the models continue to show a
notable signal for more widespread heavy amounts developing further
east into parts of central Texas. Continued to extend the Slight
Risk from eastern New Mexico and West Texas out into parts of
Northwest Texas and the Hill Country. Persistent southerly flow
will support a widespread area of PWs AOA 2 inches (+3 std dev),
supporting the potential for heavy amounts. The Slight Risk was
drawn to include areas where the 00Z HREF showed high neighborhood
probabilities for amounts of over 2 inches, with notable
probabilities for amounts of 3 inches as well.

...Eastern Oklahoma to central Louisiana...
A slow-moving returning boundary is expected to become the focus
for deeper moisture (PWs ~2 inches), which along with daytime
heating and modest mid-to-upper level forcing, is expected to
produce a swath of slow-moving storms later today, capable of
producing heavy rainfall rates and accumulations. The overnight
HREF shows a decent signal for some locally heavy amounts,
especially from central/southeastern Oklahoma through the ArkLaTex
into central Louisiana. Neighborhood probabilities for amounts
over 2 inches are above 50 percent across this region. Given the
relatively high FFGs covering much of this area, opted to introduce
just a Marginal Risk area at this time.

...Southeast...
Not much change from the previous outlook, with heavy rain
associated with a slow-moving wave developing along the trailing
end of a front settling along the Gulf Coast. Supported by onshore
flow ahead of the wave as it develops neat the Florida Big Bend
and drops south, the heaviest amounts are still expected to focus
along the Sun Coast. HREF neighborhood probabilities for amounts
above 3 inches are well above 50 percent across this region.
Therefore, the Slight Risk was maintained. Guidance continues to
show a sharp gradient further inland. Therefore, just a Marginal
Risk was maintained across much of the remaining peninsula and
further north along the Southeast Coast.

...North Dakota/Northwest Minnesota...
Storms are expected to develop later this evening across North
Dakota along a slow-moving warm front and ahead of a subtle
shortwave moving into the High Plains. Southerly flow is expected
to support an uptick in PWs (~1.5 inches). While widespread heavy
amounts are not expected, models do show some potential for locally
heavy amounts, bolstered by a period of slow-movement followed by
training cells. A Marginal Risk was introduced for the area where
the HREF showed high neighborhood probabilities for amounts over an
inch. The HREF indicates the greater threat for heavier amounts
centers over northwestern North Dakota, where slow-moving storms at
the onset may produce locally heavy amounts. The HREF shows some
modest probabilities for amounts over 2 inches across this area.

...Wisconsin...
A Marginal Risk was also added over portions of Wisconsin, where a
downstream portion of the previously noted front will become a
focus for deeper moisture and slow-moving storms tonight. The
signal for heavy amounts and potential flash flooding is a little
greater across this area. Amplifying southwesterly low level inflow
will support PWs climbing to ~1.5-1.75 inches, which along with a
weak shortwave moving across the top of an upper ridge, will
support storm development. Guidance indicates slow storm movement,
with some backbuilding, supporting the potential for locally heavy
amounts. The HREF shows neighborhood probabilities as high as 50
percent for amounts over 2 inches centered over northwestern
Wisconsin.

Pereira

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