Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
359 PM EDT Tue Jun 2 2026

Day 1
Valid 16Z Tue Jun 02 2026 - 12Z Wed Jun 03 2026

...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
WEST TEXAS INTO NEW MEXICO AND NORTH DAKOTA...

...16Z Update...

The prior forecast reasoning remains on track particularly
along/north of the Gulf Coast and into Florida. Elsewhere,
scattered to widespread storm development is expected broadly
across much of the Plains both ahead of an upper-low/accompanying
surface front over the northern Plains into the Upper Midwest as
well as further south with moist southeasterly upslope flow along
the higher terrain east of the Rockies. For the southern High
Plains, weak steering flow may lead to some clustering and
sporadic/repetitive storm movements which may increase rain totals
locally. The greatest storm coverage looks to focus along the
leading edge of higher/more anomalous moisture reaching into
southeastern New Mexico with potential upscale growth and movement
directed southeasterly along this axis. However, at least based on
the latest hi-res guidance, this happens to mostly overlap sandy
soils with higher FFGs that should help to limit impacts. The
greatest threat overall will likely coincide with the more
sensitive burn scars.

To the north, stronger dynamic forcing ahead of the upper-low will
contribute to some robust thunderstorm development. Southwesterly
flow somewhat parallel to the slowly progressing front will lead to
longer-duration rainfall and help promote increased rain totals in
the 2" range, with locally higher totals of 3-4" possible. Of note
is the potential suggested in some of the hi-res guidance for an
initial round of storms over northeastern North Dakota preceding
additional development later along the front, which coincides with
the greatest HREF probabilities for totals higher than 3".

Storms may also focus along and north of an area of low pressure
and attendant surface boundary into the central High Plains with
easterly storm progression reaching into the central Plains during
the overnight hours. Lower instability compared to further south
and less dynamic forcing compared to further north leads to greater
uncertainty with both the intensity and coverage of storms, though
some locally heavier totals and at least an isolated risk of flash
flooding is noted here as well.

Putnam

...Previous Discussion...

...Dakotas...
A mid to upper level system and associated surface front will
approach the region during the period. Ahead of it, warm moist air
will expand across the area with the latest guidance showing
precipitable water values over 1.2" and by afternoon, MUCAPE values
in excess of 1000 J/kg. Deep convection firing up in the afternoon
will initially be more discrete but is expected to evolve into
linear segments as the evening commences with a ramp up late in the
period possible with the developing low-level jet.

The 00Z HREF shows the threat for rainfall totals in excess of 3"
across the Slight Risk area with the greatest potential across
central to northeastern ND (50-80 percent). Isolated maximum hourly
rainfall totals of 2 inches will be possible. For these reasons,
the Slight Risk for flash flooding looks appropriate and no
significant changes were made for this update.

...Eastern New Mexico into West Texas...
Another day of isolated to scattered thunderstorms across the
region is expected as moist southeasterly flow expands further
westward into eastern New Mexico. With cool temperatures aloft
given the baggy trough in place, this should be sufficient for
greater coverage of thunderstorms, initially tied to the terrain
and then moving eastward toward the NM/TX border. Peak hourly
rainfall totals in excess of 1 inch will be possible across eastern
NM and total amounts of 1" to locally 3" will be possible. The
Slight Risk is maintained for the potential of isolated to widely
scattered flash flooding particularly for sensitive areas like
burn scars and steeper terrain.

...Gulf Coast into South Florida...
A frontal boundary analyzed early this morning across the Gulf
Coast is expected to slowly drop southward through the period.
Along and ahead of this feature, precipitable water values range
from 1.5" to locally over 2", which is around 1.5 std above normal
for some locations. The frontal position, combined with a favorable
upper pattern, will provide the forcing for ascent today. With
expected instability values exceeding 1500 J/kg (MUCAPE) during
peak heating, scattered to numerous showers and thunderstorms are
likely.

The latest HREF probabilities show potential for hourly rain
totals between 1-2" (up to 50 percent probability), peaking during
the afternoon to early evening hours. Totals of 1-3" are expected
within the risk area, with isolated totals of 3-5" possible in the
strongest/slowest thunderstorms, most likely to occur across
portions of FL Panhandle and across South Florida. Isolated to
scattered instances of flash flooding are possible given the
potential for intense rain rates, particularly over sensitive
locations like urban corridors.


Taylor


Day 2
Valid 12Z Wed Jun 03 2026 - 12Z Thu Jun 04 2026

...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL ACROSS WEST TEXAS
INTO NEW MEXICO AND THE EASTERN DAKOTAS...


...2030Z Update...

A few changes as well as a categorical upgrade have been provided
for this update. First, the Slight Risk covering portions of the
southern High Plains has been extended northeastward to include the
eastern Texas Panhandle as well as portions of western Oklahoma.
The now available hi-res guidance is suggestive of locally heavy
rainfall totals in the 3-4" range along a north/south oriented axis
of higher moisture south of an area of low pressure and attendant
surface boundary. HREF probabilities of >3" are in the 25-45% range
with low-end probabilities (15%) for > 5". The hi- res guidance is
a bit more ambiguous to the southwest over west Texas and
southeastern New Mexico, with the greatest potential for heavy
rainfall similar to Tuesday across southwest Texas into
southeastern New Mexico where an axis of higher/more anomalous
moisture will reach further to the west into the higher Plains
terrain and ahead of the Sacramento mountains. There may ultimately
be a lull in storm coverage/intensity and attendant flash flood
risk between these regions where relatively lower moisture is
present, but have left a broad Slight Risk for now with the
potential to further refine the outlook with additional forecast
guidance.

Second, a Slight Risk has been introduced for portions of the
northern Plains covering southeastern North Dakota, northeastern
South Dakota, and far western Minnesota. A more focused area of
convection is expected ahead of a wave of low pressure along the
cold front with the potential for upscale growth into an organized
convective system. Now available hi-res guidance shows the
potential for totals into the 2-3"+ range with low to moderate HREF
probabilities of 3"+. The one caveat is that the more progressive
nature of the front and subsequent convection compared to Tuesday
may limit rainfall duration. However, there remains the potential
for backbuilding convection to the southwest to compensate for the
faster progression of the convection particularly if the surface
wave helps to locally slow the front's southerly progress.

Finally, a Marginal Risk has been included for South Florida.
Another day of afternoon thunderstorms with the potential of
localized totals into the 3-5" range could lead to isolated
flooding concerns for urban areas.

Putnam

...Previous Discussion...

...West Texas into New Mexico...
Weak troughing aloft and the remaining relatively higher moisture
in place across the region will likely promote the development of
isolated to scattered thunderstorms again on Wednesday. The focus
for the greatest concentration of thunderstorms and rainfall totals
will shift a bit further east this day, likely along the NM/TX
border into the TX Panhandle where amounts of 1-2" with isolated 3"
totals likely. Isolated to scattered instances of flash flooding
will be possible.

...Great Plains...
An axis of higher moisture will be present ahead of an advancing
cold front moving across the Northern Plains. Moist unstable air
ahead of it will promote the development of several clusters of
thunderstorms capable of producing intense rain rates between
1-2"/hr. Isolated to scattered flash flooding is anticipated with a
possible upgrade to a Slight Risk needed for parts of eastern ND
and far western MN if trends continue for a more concentrated area
of thunderstorms and heavy rainfall.

Taylor

Day 3
Valid 12Z Thu Jun 04 2026 - 12Z Fri Jun 05 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE PLAINS, UPPER MIDWEST, AND TEXAS...

...2030Z Update...

The previous forecast remains supported by the latest model
guidance. There continues to be a signal for locally heavier
rainfall ahead of the front across portions of the northern
Plains/Upper Midwest potentially supportive of an upgrade to a
Slight Risk. However, ensemble probabilities for rainfall totals
greater than 1 inch remain very low. Additionally, spatial
disparity of heavier totals in the deterministic guidance due to
uncertainty of the position of the front do not provide enough
confidence for an upgrade at this time.

Putnam

...Previous Discussion...

...Northern Plains into the Upper Midwest...
Shortwave energy ejects into the Plains during the period with the
frontal boundary expected to become increasingly west to east
oriented as it drapes across the Upper Midwest by Thursday. This
will allow the moisture to pool ahead of it while also creating a
more favorable setup for training/repeating thunderstorms that are
expected to develop during the peak heating and continue into the
overnight hours with the surging low level jet. While there remains
uncertainty on placement (north solutions versus some that are
further south), the ingredients appear to be in place for heavy
rainfall from portions of the Dakotas eastward toward Minnesota.
For now, a Marginal Risk remains in place but an upgrade to a
Slight Risk may be needed in future updates if trends continue for
a training thunderstorm scenario.


...Plains to Texas...
A mid to upper level system slowly moving east out of western
Mexico will approach the region during the period. As it does so,
it will continue to pull into the area copious amounts of Gulf
moisture. This will bring additional rounds of thunderstorms to the
area, some of which will be locally heavy given the PWs in place
and potential for repeating rounds. For now, will keep a Marginal
Risk in place, but if greater organization of storms or confidence
on specific areas rises, a Slight Risk may be needed for portions
of western to central Texas with future updates.


Taylor


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