Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
404 AM EDT Fri Jul 3 2026

Day 1
Valid 12Z Fri Jul 03 2026 - 12Z Sat Jul 04 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF IOWA
AND EASTERN NEBRASKA...

...Northern/Central Plains to the Midwest...

A quasi-stationary frontal boundary remains draped through the
Upper Midwest under faster mean flow rounding the eastern upper-
ridge. Embedded upper- wave(s) will help to encourage storm
development with daytime heating. Seasonably high moisture (PWATs
1.5-2") and instability (ML CAPE 3000-4000 J/KG) will also continue
to support robust storms capable of heavy downpours with now-
available hi-res guidance supporting locally heavy totals of 3-5".

Heavy rainfall for portions of central and eastern Iowa expected
early Friday from a dying MCS. A renewed MCS will develop by Friday
evening across eastern Nebraska and will track eastward through
southern Iowa. This southward track will give northern parts of
Iowa a reprieve from the multi-day heavy rainfall. Significant
localized flash flooding could occur from eastern Nebraska and
southern Iowa due to much heavier hourly rainfall rates. A Slight
Risk area cover from eastern Nebraska to the
Iowa/Wisconsin/Illinois borders. Showers and storms will develop
east from there through the Chicago metro and along Michigan's
southern border through the day, but short residence times of the
heavy rainfall due to sufficiently fast movement of the storms
should keep any flash flooding risk in these areas isolated and
consistent with a Marginal Risk.

...Southeast Florida...

Afternoon convection expected to develop/increase across the middle
of the state south of Lake Okeechobee, then slowly drifting east
towards the urban corridor from West Palm Beach south, where any
isolated flash flooding threat exists. A small Marginal Risk area
was maintained.

Putnam/Campbell


Day 2
Valid 12Z Sat Jul 04 2026 - 12Z Sun Jul 05 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL STRETCHING FROM
THE NORTHERN/CENTRAL PLAINS THROUGH THE MIDWEST, OHIO AND TENNESSEE
VALLEYS, AND MID-ATLANTIC...

With the upper ridge weakening, there will be at least an isolated
threat for excessive rainfall and flash flooding potential from the
Plains to the Mid-Atlantic region for this period. High moisture
and instability will remain in place along the northern side of the
ridge ,south of the frontal boundary, with at least scattered
thunderstorms likely with the daytime heating. The potential for
greater coverage of heavier rainfall, higher totals, and more
scattered instances of flash flooding is greatest over the
Northern/Central Plains into the Upper Midwest where embedded
upper-wave(s) will help to encourage more widespread thunderstorms
and the possibility of more organized convective systems.
Uncertainty remains on where the highest concentration of heavy
rainfall will materialize, hence the broad area with a Marginal
Risk for flash flooding. However, another MCS will likely
materialize along the Nebraska/Northeast Kansas/Northwestern
Missouri corridor Saturday night/overnight and will be progressive
in nature.

Putnam/Campbell


Day 3
Valid 12Z Sun Jul 05 2026 - 12Z Mon Jul 06 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE MID-ATLANTIC...

The pattern setting up during this period is favorable for heavy
rainfall, especially near the Appalachians and locations east
toward the Eastern Shore. A low to mid level trough interacting
with a backdoor front should provide a focus for heavy rainfall
and at least moderate levels of instability should overlap with
PWs over 2" across portions of the region. There will also be the
potential for training and backbuilding of convection as westerly
flow aligns with the boundary. A Slight Risk area covers most of
Pennsylvania, Maryland, northern Virginia, and portions of
Delaware and New Jersey. A broad Marginal Risk area spans from
eastern Oklahoma eastward to the Mid-Atlantic/southern portions of
the Northeast.

Campbell


Day 4 and Day 5
Valid 12Z Mon Jul 06 2026 - 12Z Wed Jul 08 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE MID-ATLANTIC ON MONDAY...

The heavy rainfall potential along the wavy front over the Mid-
Atlantic will carry over from the Day 3 period into the Day 4
period. A Slight Risk area is in effect for much of the same
locations over northern Virginia, Maryland, northern Delaware, New
Jersey and eastern 2/3 of Pennsylvania. A Marginal Risk area spans
from Mississippi northeastward to the Mid-Atlantic coast and
northward into Upstate New York and southern New England.

Campbell


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