FOUS30 KWBC 220945
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
545 AM EDT Mon Jun 22 2026

Day 2 Valid 12Z Tue Jun 23 2026 - 12Z Wed Jun 24 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN EFFECT OVER
PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS TO LOWER MISSISSIPPI VALLEY...

...Central and Southern Plains to Lower Mississippi Valley...

The morning period on Tuesday will be one to monitor as lingering
heavy convection across the ArkLaTex to the I-20 corridor could
enhance flash flood prospects early on in the forecast, a lingering
potential that would carry out of the D1 period. Multiple CAMs and
even the ML are suggesting heavy rains would carry over from the
overnight period into early Tuesday morning with prob fields just
north of the DFW metro actually quite impressive for >3" of
additional rainfall in the 12z Tue to 00z Wed window, running
between 30-60%. This would easily lend to flash flooding
capabilities in the urban corridor, even some of the larger towns
surrounding due to the prominent urban sprawl in place. This is
certainly a period to watch as the evolution from the previous
period will dictate the threat in the D2. For now, a SLGT risk was
added to encompass the area of greatest concern for the front half
of the period.

As we head into the afternoon and evening hours, the mid and upper
pattern across the Western and Central U.S. will setup into a
persistent northwesterly flow regime with multiple shortwave
ejections out of the Rockies allowing for a maturation of
thunderstorms over the High Plains during peak diurnal instability.
From there, organization of thunderstorms are likely to occur as
they migrate downstream and mature with sufficient mid-level shear
presence to maintain any thunderstorm complex generation. This is a
relatively classic MCS pattern for this time of the year with heavy
rain prospects likely to occur from the Front Range down through
KS/OK, eventually migrating into the Lower Mississippi Valley by
the end of the forecast period. Totals on D2 are consistent
within the means with 1-2" rainfall coverage encompassing a large
portion of the Central High Plains down through OK. This puts
emphasis on heavy rainfall over the western half of KS into OK for
the period with a chance for locally 3+ inches in some of the
hardest hit locations. These areas will have already been subject
to heavy rainfall in recent periods, so grounds could still be
somewhat saturated and more susceptible to flash flooding upfront.
Given the consistent signal and ensemble QPF forecast, a SLGT risk
was added across the above area with the heaviest rainfall likely
to occur over western KS into northern OK.

...Southeast Virginia...

Shortwave ejecting out of the Tennessee Valley will make headway
into the southern Mid Atlantic with several pieces of guidance
indicating a small focused area of heavy rainfall across the
Hampton Roads area of southeast Virginia. The approach of the
shortwave trough is aiding in development of a surface low off the
VA Capes leading to a narrow corridor of enhanced convergence
across the Tidewater during the period Tuesday morning. CAMs are
generally aggressive with local maxima between 2-3" across the
Tidewater, an area more prone to flash flooding due to urbanization
factors present. HREF neighborhood probabilities for >2" are up
between 50-70% across the area, a threshold that would be
sufficient for flash flood potential, especially when you combine
the rate factors of 1-2"/hr most likely in the strongest cell
cores given the suitable environment in place. Considering the
probabilities and the expectation for locally heavy rainfall, a
small MRGL risk was added over southeast VA to account for the threat.

Kleebauer


Day 3 Valid 12Z Wed Jun 24 2026 - 12Z Thu Jun 25 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN EFFECT OVER
PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS TO LOWER MISSISSIPPI VALLEY...

A repeat from the D2 pattern will ensue for the afternoon and
evening time frame Wednesday with another round of upscale growth
from convection that matures over the High Plains and slides
southeast within the prevailing northwesterly flow aloft. This
threat seems to have a bit more of an emphatic tone to it thanks to
models depicting a stronger mid-level disturbance ejecting out of
the Rockies this period which would provide greater magnitude for
any organized convective regime that occurs. Models are also trying
to focus some training convection across portions of the area
between northeast OK into the Ozarks of MO/AR in conjunction to the
previous complex moving through the area. Upwind vectors are
favored for back-building potential in the region when assessing
forecast soundings with some models incredibly aggressive with the
QPF output in the time frame between 12z Wed and 00z Thu. There's
still some discrepancy in the magnitude and exact placement of the training/back-building regime, however this is a pattern where a
setup like this is favored, so it will bear watching. For the time
being, a SLGT risk was added to D3 across the Central High Plains
down through portions of the Southern Plains to the Lower
Mississippi Valley. The alignment of the risk matches the recent
First Guess Fields for the period and correlates with the precip
maximum positioned within the ECENS and EC-AIFS ensemble forecasts.

Kleebauer


Day 4 and Day 5 Valid 12Z Thu Jun 25 2026 - 12Z Sat Jun 27 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PARTS OF THE
CENTRAL PLAINS TO THE OZARKS ON THURSDAY...

Day 4...By Thursday the upper pattern is expected to remain mostly
zonal across the central U.S. as troughing exists over the Great
Lakes and a deeper trough approaches the Pacific Northwest.
Meanwhile, subtle shortwaves rounding an upper high over northern
Mexico and eventually tracking eastward across the Great Basin and
central Rockies Thursday will eject into the central Plains. A
frontal boundary will also be positioned across the central Plains
and connected to a surface low over the Great Lakes. This will
provide a focus for scattered thunderstorms to occur over the
central United States. Moisture is forecast to pool along this
boundary and PWs should remain around 2", which will allow for any thunderstorms to contain intense rainfall rates. Latest
deterministic and ensemble guidance highlight a swath of 2-3" QPF
from central KS and northern OK to the mid-Mississippi Valley.

Given the convective mode locally higher totals are expected. NBM
and ECENS ensemble probabilities are 30-60% for at least 1" of
rainfall in this region. Uncertainty remains with respect to
mesoscale details and won't be resolved for a few more days, but
synoptically there is potential for the frontal boundary and heavy
rain to fall north of the current SLGT risk. This will be monitored
with future updates. Additionally, this part of the country has
received heavy rainfall recently and is forecast to receive more
prior to the day 4 forecast period, so antecedent ground conditions
will support the potential for scattered flash flooding.

Increasing moisture and IVT over the central Great Basin provides
some risk for rainfall and locally heavy rain over the sensitive
slot canyon region of Utah and northern Arizona, but mean layer
flow appears fast enough at the moment to limit the flash flood threat.

Day 5...Deepening upper trough over the Pacific Northwest on Friday
increases downstream ridging and shifts the heavy rainfall threat
along the aforementioned frontal boundary east-northeast from the
Ozarks to the Ohio Valley. Less signal and focus for heavy rainfall
exists compared to day 4, thus the MRGL Risk in place. However, NBM
and ECENS probabilities for at least 1" of rain are between 20-40%
and PWs do remain near the 90th climatological percentile, so
future upgrades are possible should convection organize along the
frontal boundary and overlap with wet antecedent ground conditions.

Snell
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

FOUS30 KWBC 250759
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
359 AM EDT Thu Jun 25 2026

Day 2 Valid 12Z Fri Jun 26 2026 - 12Z Sat Jun 27 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN EFFECT OVER
PORTIONS OF THE MID-MISSISSIPPI AND OHIO VALLEYS...

...Mid-Mississippi and Ohio Valley's...

Shortwave ejecting out Missouri Friday morning will continue to
progress through the Ohio Valley the rest of the D2 time frame. Quasi-stationary front will remain positioned along and just north
of the Ohio River leading to an emphasis on convection within
proximity of the boundary. The 00z HREF does not go beyond the 00z
Saturday hour, however, the 12hr period between 12z Fri - 00z Sat
is very much indicating some significant rainfall in-of that area
of the Mississippi/Ohio River confluence and surrounds. HREF
neighborhood probabilities for at least 3" in that 12hr period are
solidly between 30-60%, a signal that usually correlates to heavy
rainfall with rates sufficient for flash flood prospects.
Thermodynamically and kinematically, this setup is one that favors
locally significant rains with most guidance in agreement on areas
of 2+ inches during the back end of D1 heading through D2. The
threat will continue to extend east through southern IN and OH with
the eastward advancement likely to extend as far as western PA down
through the Central Appalachian front in PA/MD/WV. Current
indications are for the heaviest rain to likely focus west of I-79
in WV, so the SLGT risk remains situated closer to the OH/WV/KY
border and points west with a MRGL further east. A high-end SLGT is
forecast over the confluence area of the Mississippi/Ohio rivers
and surrounds, which includes: southern IL/IN, eastern MO, and
western KY where consensus for 2-4" has grown over the course of
the last 24hrs.

...Montana...

A potent shortwave trough will migrate through the interior
Northwest U.S. leading to a regionally amplified setup capable of
producing locally heavy rainfall across central and eastern MT.
Steering flow will be pretty fast overall, so any convective
activity will likely be moving relatively quickly with the flow to
the east-northeast after genesis. That said, environment for mature mesocyclones and stronger convective cores will be capable for
periods of heavy rainfall during any of these thunderstorms as they
migrate through the High Plains of MT. Rates between 1-1.5"/hr will
be plausible at peak intensity leading to pockets of 1-2" of rain
falling in a short window as storms traverse over the area. The
previous MRGL risk was maintained to account for the threat.

...Northern ME...

Shortwave trough moving through Quebec will pivot across northern
ME as we move into Friday afternoon. Sufficient buoyancy and mid-
level forcing brought upon by the disturbance and boundary layer
priming in the afternoon will lead to a round of thunderstorms
capable of producing locally enhanced rainfall that could impact
more sensitive areas of northwest ME. As of now, the prospects for
locally 1-2" of rainfall have increased the past succession of runs
from NWP with some deterministic outputs pointing to a quick inch
or more over the northern Appalachian area of western ME advancing
into interior Aroostook county in northern ME. The previous MRGL
risk was maintained for the threat as guidance still favors the
potential.

Kleebauer


Day 3 Valid 12Z Sat Jun 27 2026 - 12Z Sun Jun 28 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN EFFECT OVER
PORTIONS OF THE OHIO VALLEY...

...Ohio Valley...

Longwave pattern begins to pivot toward a more amplified western
trough with a ridge rapidly materializing across the Southeastern
U.S. as we step through the weekend. A broad upper trough will be
positioned over the Pacific Northwest through the interior with a
succession of strong mid-level shortwaves ripping through the lead
side of the mean trough. There's growing support for a mid-level
shortwave to eject out of the Central Plains on Saturday morning
and migrate east-southeast through the Mid-Mississippi Valley,
eventually making headway into the central and southern Ohio Valley
by Saturday afternoon as it moves around the northern periphery of
the ridge building to the south. Heavy rainfall from the previous
period will act as a primer for any additional rainfall leading to
a heightened threat for flash flooding in those terrain locations
in eastern KY up into WV. CSU First Guess Fields have the region
firmly in the MRGL risk just given the signal, however the
antecedent ground conditions will favor a tick up in the forecast
risk with a SLGT risk in place across the aforementioned area.
Hardest hit locations with convection Saturday afternoon and
evening will likely see 1-2", locally higher during the threat
which would be sufficient for at least scattered flash flood
prospects for the D3. The previous forecast was generally
maintained with the SLGT risk extended a bit further north up the
I-79 corridor towards Morgantown, WV.

...Northern Plains...

Robust upper trough will be positioned over the Pacific Northwest
and the interior with falling heights and an ejection of several
stronger shortwaves pivoting around the primary upper circulation.
A period of strong to severe thunderstorms are forecast in-of the
High Plains of MT and ND as a robust shortwave makes an appearance
by late-Saturday afternoon through the evening. Ample shear and
moisture anomalies creeping above the 90th percentile up over the
Northern Plains will be sufficient in locally enhanced rainfall
rates, especially in any supercell cores and multi-cell mergers
that transpire once the LLJ kicks in after 00z. A broad MRGL risk
is in effect for the threat up across the area with a potential for
a targeted upgrade in future updates once the CAM signals come into
their temporal windows.

Kleebauer


Day 4 and Day 5 Valid 12Z Sun Jun 28 2026 - 12Z Tue Jun 30 2026

...The probability of rainfall exceeding flash flood guidance
values is less than 5 percent...

Oravec
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)