Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
849 PM EDT Sun Jul 19 2026

Day 1
Valid 01Z Mon Jul 20 2026 - 12Z Mon Jul 20 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHWESTERN U.S. FROM WEST TEXAS TO SOUTHWESTERN UTAH, AND EASTERN
NORTH CAROLINA...

01Z Update...
Only minor changes needed to the previously highlighted areas given
the synoptic pattern largely remaining the same. Some territory was
removed from the Marginal Risk area in the Ohio/Tennessee Valley to
the Virginia Tidewater in response to the southward progression of
a front in the area. However...locally heavy rainfall is a concern
farther south in closer proximity to Tropical Depression Two. At
the same time...expanded the Marginal a bit westward in the Dakotas
based on short term radar trends with additional convection still
possible once the low level jet develops. No change needed in the
West.

Bann

Previous Discussion...

...Southwestern U.S...

Overall, the synoptic pattern remains much the same, with the
monsoon ridge remaining favorably aligned. PW anomalies of 2-3
standard deviations above normal will remain across much of the
highlighted area. This moisture, along with sufficient instability,
and areas of enhanced ascent afforded by easterly-drifting mid-
level energy will support another day of scattered to widespread
convective activity. Slow storm motions along with cell mergers
will raise the threat for locally heavy amounts and flash flooding
concerns, particularly for slot canyons, dry washes, burn scars,
and low desert areas via mountain outflows. The Slight Risk
highlights the area where HREF and REFS guidance indicate the
threat for 1-2 inch amounts is greatest. The main change from
overnight is a reduction in the northward extent of the Slight Risk
area over Utah, now confined to far southwestern Utah. Warmer 700mb
temperatures north of the Grand Canyon will likely limit the areal
coverage of convection, with a broad Marginal Risk remaining
valid.

...Lower Missouri Valley to Southeastern Virginia and Eastern North
Carolina...

A targeted Slight Risk remains centered over eastern North
Carolina and extends into southeastern Virginia. Convection will
develop ahead of a slow-moving cold front that will be dropping
south into a very moist (PWs 2+ inches) and unstable (MUCAPE >
2000 J/kg) environment, while some modest right-entrance region
upper jet forcing will offer some enhanced ascent. Heavy totals
appear likely, with both the HREF and REFS showing high
neighborhood probabilities for some 2 to 4 inch totals within the
Slight Risk area, mainly between the Hampton Roads area and
Morehead City. There was a minor northward adjustment of the
Marginal and Slight Risk areas across central Virginia to account
for the latest model trends compared to the overnight issuance.

Less organized activity is expected back along the front extending
across the southern Appalachians, Tennessee Valley, and parts of
the lower Ohio, mid Mississippi, and lower Missouri valleys. While
widespread heavy totals are not expected, the moisture-rich
environment (PWs 1.75-2 inches) is expected to support storms
capable of producing localized heavy amounts and isolated runoff
concerns.

...Eastern Dakotas into the upper Mississippi Valley...

A shortwave moving off of the top of the western U.S. ridge will
interact with a frontal system advancing through the northern
Plains into the Upper Midwest. An amplifying west-southwesterly
low level jet will support increasing PWs (1.75-2 inches) and
instability ahead of a frontal boundary. The models have trended the
axis of heaviest rainfall farther north into central and northern
Minnesota, and therefore the existing Marginal Risk area has been
extended to the Minnesota/Canada border. Any new burn scar areas
will be more susceptible to potential flood issues.

...Eastern Gulf Coast into the Southeast...

Newly formed Tropical Depression Two is idling in place across the
northeastern Gulf about 150 miles south of Panama City, Florida.
Recent radar imagery indicates the core of convection and heaviest
rainfall well offshore, and the latest CAM guidance suite
suggests this will remain the case going through the remainder of
the afternoon and into tonight. However, some heavier amounts
along the west coast of Florida are likely with outer feeder bands
and could lead to some localized instances of flooding where
training convection develops. Therefore, the Marginal Risk was
maintained from the overnight issuance.

An axis of enhanced low level convergence and pooling moisture to
the north is still expected be a focus for diurnal storms capable
of producing heavy rainfall rates. Therefore, a Marginal Risk was
maintained from the central Gulf Coast northward into the Tennessee
Valley. Recent CAM guidance indicate localized totals of 1 to 3 inches
across portions of this region through early evening where the most
persistent convection develops.

Pereira/Hamrick
 

Day 2
Valid 12Z Mon Jul 20 2026 - 12Z Tue Jul 21 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE DESERT SOUTHWEST AND NORTH CAROLINA...

...Southwest and Great Basin...

Mid-level energy moving west of the region, and dry air advection
from the south will begin to diminish the heavy rainfall and flash
flooding threat over West Texas. However farther west, the
monsoonal moisture plume will remain firmly in place, ensuring
another day of efficient rainfall production over portions of the
Southwest and Great Basin. Models show the upper high originally
centered over Utah and Colorado beginning to slide southeast,
allowing moisture and energy to spread northwest into the Great
Basin and along the western slopes of the Sierra Nevada, raising
the potential for increasing storm activity and isolated runoff
concerns in those areas.

The greater heavy rainfall and flash flooding threat will remain
focused from southwestern New Mexico and southeastern Arizona
northwestward along the Mogollon Rim into northwestern Arizona.
This is expected to be the focus for better synoptic forcing and
greater instability, supporting intense short-duration rain rates
that will elevate the risk for flash flooding, especially in areas
of complex terrain, dry washes, and burn scars. For the 19Z Update,
a minor westward extension of the Slight Risk was made across
northwestern Arizona to the Lake Mead area.

...Upper Great Lakes...

An amplifying upper trough supported by energy diving out of
Canada will advance from the upper Mississippi Valley to the upper
Great Lakes. Strong southwesterly to west-southwesterly low level
inflow will continue to sustain deep moisture ahead of the cold
front and across the advancing warm front. This moisture along with
strong forcing, produced in part by left-exit region upper jet
dynamics, will generate organized convection capable of producing
rainfall rates of 1-2 in/hr. Fast storm motions should limit the
overall heavy accumulation and flash flooding threat. However,
localized short-term training could raise at least some isolated
concerns. No changes were needed here for the updated Day 2
outlook.

...North Carolina and Southern Virginia...

A lingering boundary and corresponding pool of deep moisture
convergence, with PWs generally near or slightly above 2 inches,
will support additional thunderstorms capable of producing heavy
downpours. There has been a trend for heavier QPF in today's
guidance across much of central and eastern North Carolina, and
after consultation with the local WFOs, a Slight Risk area has been
introduced for this area. Heavy rainfall expected through Sunday
night will lead to reduced FFGs and more saturated soils that will
be more prone to flooding issues.

...Gulf Coast...

The models continue to show the footprint of the heaviest amounts
associated with Tropical Depression Two over the northern Gulf
remaining mostly offshore. The Marginal Risk has been maintained along
the coast from West Florida near Tampa, to southeastern Louisiana,
which encompasses areas generally along the Interstate 10 corridor,
with the highest totals likely near the Big Bend of Florida. Moisture
pooling along an axis of enhanced low level convergence northwest
of the circulation may extend the threat for heavy rainfall further
inland into the far lower Mississippi Valley. If there are
northward trends in later model cycles, it is possible that a
Slight Risk could eventually be needed for portions of this outlook
area.

Pereira/Hamrick
 

Day 3
Valid 12Z Tue Jul 21 2026 - 12Z Wed Jul 22 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHWEST AND EASTERN KENTUCKY TO THE DELMARVA...

...Southwest to the northern Rockies...

Models show the upper high continuing to shift east as an upper
trough begins to drift into the Pacific Northwest. This will allow
the monsoon moisture plume to spread farther north, with moisture
anomalies over 3 standard deviations above normal extending as far
north as the northern Rockies. This will support increasing
convective development with isolated flash flooding concerns as far
north as southwestern Montana and southern Idaho.

However, the greater heavy rainfall and flash flooding threat is
expected to remain centered over western New Mexico, central and
northern Arizona, and southern Utah. Guidance shows a fairly well-
defined shortwave moving around the western periphery of the upper
high, which along with PWs over 1.5 inches in many spots, and
highly sensitive soils, will likely generate additional widespread
storm coverage and flash flooding concerns. Given the synoptic
setup and anomalous moisture, this can be considered a high-end
Slight for parts of Arizona and a potential upgrade to Moderate
Risk may be required in future outlooks if models trend higher.
No major changes were needed for this region in the 20Z update.

...Ohio Valley to the Mid-Atlantic...

Upon examination of the 12Z model and CAM guidance suite, there is
a general upward trend in expected QPF across more of the region to
include the central Appalachians and Blue Ridge Mountains, and
therefore the two existing Slight Risk areas were merged into a
single larger area extending from eastern Kentucky to the DelMarVa.
Moist soils and flood-prone mountain terrain are likely to
contribute to the flash flood threat across this region. Deep
moisture (PWs around 2 inches) will fuel showers and storms ahead
of a strong cold front advancing southeast across the region. These
storms will be capable of producing 1-2 in/hr rainfall rates,
raising flash flooding concerns. The Marginal Risk area was also
extended northeastward to include more of central New England where
some of the deterministic guidance supports the idea for some 1-2
inch rainfall maxima.

Farther east across the Mid-Atlantic, strengthening southeasterly
flow ahead of the system moving through the Ohio Valley will
transport an anomalous moisture plume into a region of strong
ascent. This combination will support increasing coverage of
showers and storms capable of producing heavy rainfall. While the
exact spatial coverage of heaviest amounts remains somewhat
uncertain, portions of the the more flood-prone urbanized I-95
corridor could be impacted, warranting the continuance of the Slight
Risk area.

...Gulf Coast...

With the heavy rainfall footprint associated with Tropical
Depression Two remaining offshore in most of the guidance, we
continued to maintain only a Marginal Risk for the central/eastern
Gulf Coast that is mainly confined to the Interstate 10 corridor
and to the coast. Any northward trends will need to be monitored in
case the heavier core of rainfall reaches the coast, which could
necessitate the need for a future Slight Risk.

Pereira/Hamrick
 

Day 4 and Day 5

Valid 12Z Wed Jul 22 2026 - 12Z Fri Jul 24 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ALONG PORTIONS OF
THE SOUTHEAST US AND CENTRAL/WESTERN GULF COAST...

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
INTERMOUNTAIN WEST AND CENTRAl PLAINS ON WEDNESDAY...

2030Z Discussion...
Introduced a Slight Risk area along the central Gulf coast on
Tuesday and central to western Gulf coast on Wednesday along the
path of Tropical Depression 2. Given the amount of shear across the
system...the maximum rainfall amounts be displaced to the south of
the system which would place it in very narrow corridor along the
coast or placed off-shore. But the on-shore fetch of moisture
around the center is enough to warrant a Slight for the time being.
Until the degree of ridging to the north is resolved...and how
much dry air that feeds into the system or its influences on the
track...there is too much uncertainty to highlight any more than a
Slight Risk area at this point.

Otherwise...introduced a SLight Risk area over portions of the
Central US as shortwave energy ejecting from the Rockies interacts
with a low level boundary to produce convection in an anomalously
moist airmass capable of supporting locally heavy rainfall.

No other changes needed elsewhere.

Bann

Previous Discussion...

...Tidewater Region of Virginia and the Carolinas...

A slow-moving cold front pushing southeast out of the Mid-Atlantic
on Wednesday is likely to continue slowing down its forward speed
as it approaches the Tidewater Region of Virginia and the Carolinas
on Wednesday. Meanwhile, plentiful tropical moisture will be drawn
northeastward from the tropical system that will likely be
meandering somewhere near the Louisiana coast on Wednesday. This
moisture will ride northeastward ahead of the front, spiking PWATs
above 2.25 inches over this entire region. The result of a strong
but slow-moving front, well above normal amounts of moisture, and
upper level support in the form of a deep trough over the Northeast
supporting the surface front from behind/north will make for a
nearly ideal scenario for training and backbuilding storms from the
afternoon through the evening.

This Day 4/Wednesday period is likely to be the fourth consecutive
day that showers and thunderstorms have been dropping locally very
heavy rain and multiple-inch rainfall totals somewhere in and
around eastern North Carolina. The front will act to greatly expand
the footprint of heavy rainfall in this area. Since soils are all
but certain to be nearly saturated in this area by Wednesday, flash
flooding concerns continue to increase. Thus, a higher-end Slight
was introduced with this update from Raleigh east, and from
Wilmington north through the Hampton Roads area. It's probable that
should the trends continue to increase both with the expected
rainfall on Wednesday, and the prior days' rainfall in this same
region, that a Moderate Risk upgrade will be needed with future
updates.

By Day 5/Thursday, the front will sag a hair bit further south,
likely sparing the Raleigh and Hampton Roads metros from much
additional rainfall, but instead concentrating the heaviest rains
from the Outer Banks southwest down the coast through Wilmington
and including Charleston, SC in heavy rainfall. The ERO thus was
started this morning with a Slight Risk for this area. Of course,
even just a small increase in forward speed will push the front up
to the coast, which would then concentrate all of the heaviest
rains off the coast, making the Slight Risk an over-forecast.
However, any slower/westward positioning of the front will make
for a 5th consecutive day of heavy rains in eastern North
Carolina...meaning the Slight Risk would be an under-forecast.
Thus, the Slight represents the "happy medium" of these scenarios
and fits best with the current rainfall forecast in the area for
Thursday.

...Intermountain West...

A Slight Risk upgrade was introduced with this update for a portion
of the Intermountain West on Wednesday. The area highlighted
includes all of southeastern Idaho, much of western Wyoming outside
of Yellowstone, as well as far northern Utah and the northwestern
corner of Colorado. Well above normal amounts of atmospheric
moisture to the tune of up to 4 sigma above normal, and PWATs
locally exceeding 1.25 inches will be in place across this region.
An approaching longwave trough will direct a strong shortwave
northeastward during the afternoon hours. This will result in
widespread shower and thunderstorm activity over this area.
Topographic interaction with the storms will locally enhance
rainfall rates, while also supporting impactful flash flooding as
the rain water races down the slopes of the mountains. Due to the
abundant moisture available, the storms will not only be numerous,
but capable of 2 inch/hour rainfall rates with the strongest cores,
a phenomenon not often seen in this part of the country.

Wegman
 

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