Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
834 PM EDT Sun Jul 6 2025

Day 1
Valid 01Z Mon Jul 07 2025 - 12Z Mon Jul 07 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
TEXAS, NORTH CAROLINA, & VIRGINIA...

...Carolinas/Southern Virginia...
Tropical Depression Chantal continues to push north across NC and
is expected to recurve northeast across southeast VA by morning.
The HREF, RRFS, and GFS guidance keeps the system convective into
the morning now...it may exit the East Coast as a tropical
depression at this rate. This should continue to result in a stripe
of higher rainfall totals, with hourly amounts to 3" and local
totals to 6". Moderate Risk impacts across urban centers cannot be
ruled out given the rain expected.


...South-Central Texas...
Afternoon and evening convection has waned, but both the 18z HREF
and 12z RRFS show a convective uptick towards 12z. Given the
sensitivity of this area and the upticks in total forecast rainfall
from the ensemble of high resolution guidance, maintained the risk
levels and shifted the areas back south to around Kerrville, which
remains sensitive due to previous days of rainfall. Model guidance
each day keeps extending the risk forward another day. Hourly
amounts to 3" with additional local totals to 6" remain possible.


...Marginal Risks Elsewhere...
Marginal Risk areas were merged across the central Plains and
Midwest, where a heavy rain threat continues into the overnight
hours. Added a Marginal Risk area across the Florida Big
Bend/northwest FL Peninsula and dropped the Louisiana Marginal
Risk. Areas were pared back based on radar reflectivity trends and
18z HREF/12z RRFS guidance. Hourly rain amounts to 2.5" with local
amounts to 5" remain possible in isolated spots within the Marginal
Risk areas.

Roth


Day 2
Valid 12Z Mon Jul 07 2025 - 12Z Tue Jul 08 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE UPPER
MIDWEST TO THE SOUTHWEST, THE NORTHEAST TO THE SOUTHERN PLAINS, AND
THE MID-ATLANTIC...

...2030Z Update...

The Marginal Risk across portions of the Northeast/Mid-Atlantic was
merged with the inherited Marginal along the coastal Mid-Atlantic
with this update. Abundant tropical moisture associated with the
remnants of Chantal will continue streaming north on Monday. While
organized convection will likely have dissipated by Monday
afternoon, the combination of ample heating and instability and
that moisture should allow for widespread convective development,
albeit disorganized, across the Mid-Atlantic. The disorganized
nature of it should preclude any more than isolated instances of
flash flooding, however the abundant moisture will favor any cells
that form to have the potential of causing locally heavy rain and
resultant flooding. The signal for drier conditions into
southeastern and eastern Pennsylvania has largely disappeared, so
the Marginals were merged.

No other changes were made to the Marginal Risks in the middle of
the country and from Texas through the Ohio Valley. The rainfall
forecast in portions of central Texas around and southeast of San
Angelo has increased a bit, associated with the same disturbance
that has been causing the rain over the past few days. With each
consecutive day the available moisture, instability, and advection
in this area decreases...so we should continue to see the drying
trend as regards coverage and intensity of convection to continue.
A Slight Risk was considered in this area, but that will be tied to
how much convection occurs this afternoon in the area, which for
now has been muted, precluding an upgrade with this update.

Wegman

...Previous Discussion...

...Eastern North Carolina to Eastern Pennsylvania and New Jersey...
Although the surface circulation may no longer be well-defined,
the mid level remnants and an its associated plume of deeper
moisture are expected to lift north from eastern North Carolina
along the Mid-Atlantic Coast ahead of an upstream trough, bringing
the potential for locally heavy rain and perhaps some isolated
flooding concerns from eastern North Carolina to eastern
Pennsylvania and New Jersey.

...Northeast to Mid Mississippi Valley/Ozarks...
A frontal boundary will continue to slide farther east across the
Northeast this period. Deep moisture ahead of the boundary (PWs
1.75-2 inches and 2-3 std dev above normal), along with favorable
upper jet forcing are expected to contribute to some organized
heavier amounts from western and northern New York into parts of
northern New England. Less organized activity is expected farther
southeast. However, once again locally heavy amounts and isolated
flooding concerns cannot be ruled out for areas back through the
Ohio Valley into the mid Mississippi Valley and Ozark region.

...Southern Plains...
The latest HREF shows that activity developing over parts of Texas
on Day 1 may continue into Day 2, producing additional heavy
amounts and prolonging flooding concerns across parts of Texas
including portions of South-Central Texas and the Hill Country
northeastward through North Texas...

...Upper Midwest to the Southwest...
Amplifying southerly low level winds over the Plains will support
increasing moisture across the central into the northern Plains.
This moisture along with mid level energy moving out into the
region, will support widespread showers and thunderstorms, with
the guidance showing a signal for organized activity developing
over the central High Plains. Forecast confidence is limited by
significant model spread in the details. However, the potential for
at least isolated flash flooding concerns cannot be ruled out.

Farther to the south, activity again is expected to be less
organized. But again, cannot rule out at least an isolated flash
flooding concern, especially across vulnerable portions of eastern
and central New Mexico.

Pereira

Day 3
Valid 12Z Tue Jul 08 2025 - 12Z Wed Jul 09 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE MIDWEST
AND THE NORTHEAST TO THE OZARKS...

...2030Z Update...

The guidance has dried out portions of Oklahoma, Texas, and New
Mexico with the latest suite. Thus, due to lack of signal, the
Marginal Risk was trimmed out of these areas, with the westernmost
extent of the Marginal now in eastern Kansas and Oklahoma.

The rainfall forecast has increased a bit across the Mid-Atlantic,
particularly in the DMV area. Should these signals persist or
increase, a Slight Risk upgrade may be needed with future updates,
but given the newness up this update with little forcing noted,
have opted to keep the area in a Marginal risk to allow for run-
to-run consistency in the guidance.

Wegman

...Previous Discussion...

...Northeast through the Ohio Valley...
A cold front will continue to slide slowly southeast across the
Northeast and the Mid Atlantic. Deepening moisture ahead of the
boundary (increasing above 2 inches in many locations) will raise
the potential for at least locally heavy amounts and isolated
flooding to occur.

...Midwest to the Southern High Plains/Rockies...
An upper level shortwave and associated axis of deeper moisture may
produce storms with locally heavy amounts from the mid Mississippi
Valley/Great Lakes region back through the mid Mississippi and
lower Missouri valleys into the southern Plains.

Meanwhile, low level upslope flow may produce another round of
showers and storms developing along the southern Rockies into the
High Plains.

Pereira

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