Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
733 PM EST Sun Nov 1 2026
Day 1
Valid 01Z Mon Nov 02 2026 - 12Z Mon Nov 02 2026
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE FOUR CORNERS REGION...
...Southwest...
16Z Update: No changes to the previous forecast as everything
remains on track for a high-end MDT across portions of the Mogollon
Rim and San Juan Mountains with a widespread MDT risk extending up
through the canyon areas of northwest AZ into southwestern UT.
HREF/REFS EAS signals for >2" of rainfall are both over 70% for
areas of the Mogollon Rim and San Juan range with neighborhood
probs for locally 5" or greater still running between 60-90% in
both areas. This is consistent from the previous iterations of both
hi-res ensemble suites, backing the current forecast and
expectation for widespread flash and riverine flooding capable of
locally considerable impacts across the outlined domain.
Kleebauer
..Previous Discussion..
Few changes were needed to the ongoing risk areas across the
Southwest. An anomalously strong atmospheric river is driving a
plume of moisture and heavy rain into the Southwest from the
Pacific. PWATs remain 4-6 sigma above normal for this time of year,
with values between 3/4 inch and 1.5 inches. Further, essentially
all of the Southwest has been in a very wet period, so this highly
anomalous event is at the tail end of a long stretch of wet weather
that has left the soils saturated already in most areas. Thus, all
of today's rains will be converting to runoff, leading to numerous
instances of flash flooding. Dry washes, arroyos, slot canyons, and
burn scars will remain the most susceptible areas.
The Moderate Risk for portions of Arizona into southern Utah
remains largely unchanged as far as the area impacted, as for much
of it, the risk area is tied to the terrain. That said, the latest
guidance shows rainfall amounts have a 70-90% chance of exceeding
the 100 year ARI. This is generally the threshold for considering a
High Risk area, which remains possible. Ultimately, the rather fast
forward speed of the plume of moisture, as well as a lack of
instability will be two limiting factors which for this update will
keep these areas shy of the High Risk threshold. Nonetheless, with
the aforementioned highly anomalous moisture and strong upper level
forcing from a pair of jet streaks and a vigorous trough following
behind the rain, expect a widespread 3-5 inches of rain into
portions of the Mogollon Rim, particularly areas most perpendicular
to the southwesterly flow and in the core of the moisture plume. A
higher-end Moderate risk is in effect for these areas, mainly north
and east of Phoenix. Into Utah, the threat for flash flooding turns
to the typical slot canyons and steep, rocky terrain, as well as
numerous large burn scars that dot the southern Utah landscape.
Each of these areas could see more severe flooding, despite not
being quite in the core of the heaviest rainfall.
A second Moderate Risk is in effect for the San Juans of southwest
Colorado. Here too, due to a very high likelihood of exceeding
100-year ARIs, a higher-end Moderate Risk was introduced. For this
area, the very recent high-impact flash flooding event from last
week is top of the mind. Expect essentially a repeat, albeit with
slightly lower snow levels. This might nominally mitigate any
flooding concerns in river basins that drain the San Juans. It's
likely that spot areas will see more total rainfall here than along
the Mogollon Rim, due to steeper topography more efficiently
wringing out the abundant moisture.
Wegman
...Southeast...
2230Z Update: Rainfall totals today have been quite prolific across
much of the lower half of the FL Peninsula -- with many areas
topping 2-4". Localized 5-10" amounts meanwhile were noted around
Lake Okeechobee, and most recent HRRRs continue to show additional
3-6+ inches through the evening hours as the well-developed MCV
continues to drift slowly across the area. The area remains within
an area of difluent flow aloft, with the strong upper level
divergence (broad-scale low-mid layer ascent) owing largely to a
90-100 kt upper level jet streak oriented N-S over the eastern
Gulf, placing much of the FL Peninsula in the left-exit region of
this jet streak. Nearly optimal dynamical forcing for widespread
convection, along with the favorable thermodynamic profile (ML
CAPEs 1000-2000 J/Kg and PWs 2.1-2.2"), are the key factors in this
impressive heavy rainfall event. We've expanded the Slight Risk,
matching the recent HRRR trends and aligning where the latest HREF
and REFS have the highest probabilities (>60%) of 3-5+ additional
inches of rain. We've also included a 25% area (high-end Slight
Risk) across parts of the southeast coast (including the Treasure
Coast), where the HREF/REFS probs of >5" of additional rainfall are
highest (40-70%). For further information, please refer to the
latest Mesoscale Precipitation Discussion or MPD #1546, which is
valid through 03Z.
Hurley
..Previous Discussion..
A westerly wave that has been traversing the Gulf will move into
the Florida Peninsula today. Abundant Gulf moisture will converge
over the Peninsula as a weak upper level trough moves over the
state, further increasing atmospheric lift. A widespread 1-3 inches
of rain is expected over much of the Peninsula. This will be the
latest in a string of days that has caused areas of heavy rainfall
over the east coast. With heavier and more widespread rain expected
today, areas where soils are already saturated from previous days
remain in a Slight Risk, which generally covers the I-95 corridor
from the Georgia line south through Miami. Some instability and an
amazing history of isolated cells producing rains of 3+ inches per
hour for 6+ hours have led to incredible rainfall totals in very
isolated spots. This may potentially continue over the lower
Mississippi Valley today. The Marginal Risk remains in place with
some small expansions.
Wegman
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
307 AM EST Mon Nov 2 2026
Day 1
Valid 12Z Mon Nov 02 2026 - 12Z Tue Nov 03 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE EAST COAST
OF FLORIDA AND FOR PORTIONS OF EASTERN KANSAS, WESTERN MISSOURI,
AND EASTERN OKLAHOMA...
...Florida...
While PWs are forecast to drop off some, persistent easterly flow
will continue to support an anomalously moist airmass -- fueling
another day of potentially heavy amounts and flash flooding along
the eastern peninsula, especially from the Space Coast down to
southeastern Florida. A Slight Risk was maintained along this
area, highlighting where both the HREF and REFS indicate localized
amounts over 3 inches are likely today.
...Midwest/Plains...
A highly-amplified and multi-stream upper trough is forecast to
move east of the Rockies into the Plains today, producing
widespread precipitation across the central U.S. A well-defined
shortwave within the base of the trough will move from the Four
Corners this morning, into the central and southern Plains by this
evening. The potential for heavy rain is expected to increase this
evening across portions of the southern and central Plains,
especially from eastern Oklahoma and Kansas into western Missouri
as a 40-50+ kt southwesterly low level jet develops ahead of the
wave, supporting strong moisture advection into a region of
increasing ascent. Showers and storms are expected to develop with
the potential for heavy rates increasing as PWs increase to ~1.75
inches and right-entrance region upper jet forcing supports large-
scale ascent. Hi-res guidance indicates that elevated storms can be
expected during the late afternoon across portions of eastern
Oklahoma into the lower Missouri Valley before a more robust line
of storms develops and advances east ahead of a sweeping cold
front. In addition to the potential for more than one round of
storms, a period of training convection may elevate the risk for
localized heavy amounts and flash flooding. A Slight Risk was added
where both the HREF and REFS show high neighborhood probabilities
for accumulations over 3 inches. Both also showed neighborhood
probabilities for amounts exceeding 3-hr FFGs increasing into the
20-30+ percent range across portions of the area during 0-6Z
Tuesday timeframe.
Farther to the north, a Marginal Risk covering portions of the
northern Plains and upper Midwest was maintained. Widespread
coverage of 1-2 inch amounts across parts of the Dakotas and
Minnesota is forecast. However, not expecting any widespread flash
flooding concerns as limited instability will keep rainfall rates
in check.
Pereira
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
307 AM EST Mon Nov 2 2026
Day 2
Valid 12Z Tue Nov 03 2026 - 12Z Wed Nov 04 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL PORTIONS OF MID-
SOUTH...
...Lower and Mid-Mississippi Valley...
The general consensus of the hi-res guidance shows that storms
developing late Monday will remain ongoing along an advancing cold
front extending from the mid Mississippi Valley back into eastern
Texas Tuesday morning. There is some indication in the guidance
that heavy rates and continued southwest-northeast training may
elevate the threat for heavy amounts and flash flooding from the
Ozark region into southeastern Missouri. This suggests an upgrade
may need to be considered at some point, but for now maintained the
outlook at just a Marginal Risk. Farther east, a Slight Risk
centered over the Mid-South was maintained -- where deep moisture
and favorable upper jet forcing are expected to support
re-intensifying storms capable of producing heavy rainfall rates.
The previous Slight Risk was largely maintained, but adjusted a
little to reflect the REFS high neighborhood probabilities for
2-3+ inches across this area.
...Florida...
Easterly flow will weaken this period; however, with anomalous
moisture remaining in place, cannot rule out additional localized
heavy rainfall amounts resulting in at least isolated flash
flooding concerns, especially in urbanized locations and areas
previously inundated with heavy rains.
Pereira
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
