Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
850 PM EDT Sun Jun 22 2025
Day 1
Valid 01Z Mon Jun 23 2025 - 12Z Mon Jun 23 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
SOUTHEAST NEW MEXICO AND WEST TEXAS...
01Z Update...
Although an isolated storm cannot be ruled out, the environment
will continue to remain unfavorable for widespread storm
redevelopment overnight across the Northeast. Therefore, the
Marginal and Slight Risk areas were removed from region.
Elsewhere, based on current observation trends and recent hi-res
guidance, minor adjustments were made to the previous outlook
areas over the central U.S. Recent runs of the HRRR and the 18Z
HREF continue to show a notable signal for heavy amounts and
potential flash flooding centered over West Texas to the New Mexico
border, with the heaviest amounts centered from the western Big
Bend Region into the Davis Mountains. HREF neighborhood
probabilities indicate that localized amounts over 2 inches are
likely in this area.
Pereira
16Z Excessive Rainfall Discussion...
New Mexico and Texas...
12Z upper air showed precipitable water values in excess of 2
inches continued to be drawn northward into West Texas...on par
with the 2 to 3 standardized anomaly precipitable water forecast
from the overnight numerical guidance. With the large scale forcing
largely in place...there were few changes needed here.
The Dakotas/Nebraska to Minnesota...
Made a few adjustments to the northern portion of the Marginal Risk
area given convective behavior earlier this morning...while a
southward expansion into northern Nebraska was based largely on a
consistent signal for convective development during the afternoon
farther south and west than indicated by the 00Z/06Z numerical guidance.
This area of convection looks to be progressive...but locally
intense rates are possible given the precipitable water values
which exceed 1.75 inches by early evening.
Bann
...New Mexico and Texas...
Today is the beginning of what will be a multi-day period of
excessive rainfall potential over portions of west TX into NM. The
mid/upper level pattern features a near record to record ridge over
the eastern U.S. and a well-defined longwave trough over the west.
Southerly flow in between these features will supply ample
moisture to NM, with a connection all the way to the Caribbean Sea.
The better forcing from the western trough will generally hold of
until Monday and Tuesday (see the day 2 and 3 EROs), but today will
still have enough moisture and instability around for scattered
convective development. In fact PWs should already be getting
towards climatological max values for late June over portions of
southwest TX and immediate adjacent areas of NM. And while the
better forcing arrives Monday, do note broadly divergent flow at
250mb Sunday which could help sustain convection.
The greatest convective coverage is expected to be across portions
of southwest TX, where this is considered a higher end Slight
risk. Deep layer mean flow is weak, suggesting slow cell motions
today. Convection forming on/near terrain will slowly move off the
terrain, with outflows likely allowing for some cell merger
activity. Given this will be occurring within a very high PW
airmass, scattered areas of flash flooding appear likely. Both the
00z HREF and REFS indicate a high likelihood of rainfall locally
exceeding 3", with at least some potential of isolated amounts
over 5". A Marginal risk extends across much of eastern NM into
adjacent area of west TX, where storm coverage should be less...but
slow moving cells will still be capable of producing localized
flash flood concerns.
...Eastern Dakotas into Minnesota...
The setup looks favorable for another round of organized
convection this afternoon and evening across the region. Strong
shortwave energy ejecting into the northern Plains, a strengthening
axis of low level moisture transport, and upwards of 4000 j/kg of
MUCAPE will drive the convective threat. The combination of extreme
instability, PWs well over the 90th percentile for late June, and
a warm front focusing convection, all point to a heavy rainfall
threat. Main uncertainty is the longevity of higher rainfall rates
and the exact axis of convection. Cells will generally be moving
along quick enough to preclude much of a flash flood threat,
however some training along the warm front over far northern MN is
possible. Activity may actually get going this morning, with some
additional development by this afternoon. Also seeing a growing
signal for convective development by this evening over southeast SD
as convergence increases along the cold front. This activity
should move northeast along the axis of the front across MN
tonight. While this activity should be quick moving, heavy
rainfall rates could still pose an isolated flash flood risk.
Chenard
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
856 PM EDT Mon Jun 23 2025
Day 1
Valid 01Z Tue Jun 24 2025 - 12Z Tue Jun 24 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
NEW MEXICO AND WEST TEXAS, AND FROM KANSAS INTO SOUTHERN
WISCONSIN...
01Z Update...
Based on current observation trends, as well as recent hi-res
guidance, removed much of the Marginal Risk area previously
covering the central High Plains, and brought the northern edge of
the Marginal Risk further south across the central Plains into the
Upper Midwest. Made mostly minor adjustments to the Slight Risk
areas, where the potential for heavy rain and flash flooding is
expected to continue through the evening into the overnight. Recent
runs of the HRRR and the 18Z HREF indicate the greatest threat for
widespread heavy amounts extends from northeastern Kansas, through
northwestern Missouri, into southern Iowa. Training storms are
expected to continue, with the 18Z HREF showing high neighborhood
probabilities (greater than 80 percent) for accumulations over 2
inches, and greater than 50 percent for accumulations exceeding 3
inches in this area.
Pereira
16Z Excessive Rainfall Discussion Update... Based on the 06Z
neighborhood probabilities...and a quick look at the probabilities
from the 12Z run...extended the Slight Risk area a bit to the east
to cover more of southern Wisconsin. In the broader picture...the
risk of excessive rainfall exists on the periphery of a broad upper
level ridge from New Mexico and West Texas...across the Central
Plains into the Upper Midwest given the persistent deep-layer
advection and embedded shortwave energy. The 12Z HREF probabilities
aligned well with the previously issued Excessive Rainfall Outlook
and only minor adjustments were needed.
Bann
...New Mexico into West Texas...
A general pattern of persistence will maintain a relevant posture
for scattered to widespread convective impacts across Southwestern
TX up through the eastern half of NM with the highest potential
impacts aligned within the terrain. Ample moisture advection
provided by prevailing southerly-oriented flow within the sfc-500mb
layer will correlate with an environment capable of locally heavy
rainfall within any cell maturation across the above areas. The
proxy of the deep layer moisture and RER jet dynamics from the mean
trough situated to the west will create an accumulated risk of
showers and storms propagating over the same areas leading to
increasingly compromised soils, or even interacting with the
already prevalent burn scars situated over the Sacramento Mtns.
Storm motions will likely be fairly weak as noted by the forecast
Corfidi vectors residing between 5-15kts on average within the
confines of the entire Southwest TX and Southeast NM domains. This
will allow for modest training concerns that will ultimately cause
problems if they fall within any of the urban centers along the
Upper Trans Pecos out into the complex topography located in the
region. The best chance for flash flooding will likely be within
those burn scar locations where hydrophobic soils are still a
problem and can promote a formidable runoff regime that could cause
significant problems locally if a heavy cell forms overhead. Areas
within the Pecos river are also notorious for flash flooding
capabilities due to the limited drainage structures prevalent
within town limits. Considering the HREF neighborhood probs for >2"
are running between 50-90% over a large area extending from the
Davis Mtns up through the Eastern NM Caprock, the previous SLGT
risk was upheld with wording of a higher end SLGT considering the
environment in place.
...Central Plains to Midwest...
The Central Plains through the Midwest continues to lie within the
northern and northwest periphery of a broad ridge extension
centered over the Mid Atlantic. The proxy of the ridge has allowed
for a persistent south to southwesterly mean flow within the
column leading to steady moisture advection within the boundary
layer up to around 500mb. Current PWATs from 00z RAOB analysis
across the Plains and Mississippi Valley denote moisture anomalies
that are approaching +2 deviations, something that has also been
reflected in the last several days of NAEFS anomalies within the
ensemble suite. The relevant moisture pooling across the zone
extending from KS up into the Midwest will lead to a formidable
widespread convective initiation scheme that will develop due to
increased convergence along and ahead of a slow-moving cold front
nosing down through the Northern Plains. The interaction of the
cold front with a very buoyant environment (MUCAPE 2500-4000 J/kg)
located across the Central Plains up into the Upper Mississippi
Valley will create a broad axis of heavy convection with the
heaviest precip likely correlated with the 2+" PWAT domain located
from North-Central KS and points northeast into IA.
There's a general consensus within the latest CAMs suite of
significant totals between 2-4" forecast located within the
aforementioned zone, including some deterministic output and lower
neighborhood prob correlation for some places exceeding 5". The
prospects for those types of totals stems from not only the
favorable deep moist convective pattern, but also the mean layer
flow and surface convergence regime along the front creating a
favorable environment for back-building convection and training
cell prospects. This is fairly well-documented when assessing
forecast Corfidi Vectors continuing this divergent storm motion
setup within the upshear and downshear calculations given the
forecast wind field(s). A strong RER jet dynamic will only aid in
a blossoming QPF field and maintenance as the mean flow takes the
convective pattern off to the northeast. This pattern will carry
through Monday evening into early Tuesday morning with some
weakening of the convective field anticipated due to loss of
diurnal destabilization. In any case, this setup is capable of
widespread 1-2" totals with the hardest hit locations likely seeing
2-4" with locally higher as noted in the latest CAMs. The saving
grace, at least initially for D1, are the drier soils centered over
the Central Plains into parts of Southeast NE and Southwest IA
leading to higher FFG indices that will need some priming in order
to likely reflect a more significant flash flood response.
The change from the previous forecast was an adjustment to the
south with the overall SLGT risk as guidance reflects a bit of a
faster frontal progression than anticipated. This places a higher
risk a bit south over Northeast KS to points northeast. The threat
for locally heavy rainfall is also forecast across Southwest KS
with cells ejecting out of the High Plains of CO/NM, but CAMs are
less defined due to the lack of a boundary layer focus
comparatively. The MRGL exists in at particular area, but if CAMs
come into agreement on a local max centered near or southwest of
DDC, then the SLGT risk may be extended further to the southwest to
account for the prospect.
Kleebauer
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
856 PM EDT Mon Jun 23 2025
Day 2
Valid 12Z Tue Jun 24 2025 - 12Z Wed Jun 25 2025
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
CENTRAL NEW MEXICO...
20Z Excessive Rainfall Discussion Update...
The periphery of the strong upper ridge/upper high will continue to
be the focus for heavy to excessive rainfall from New Mexico into
the Central/Northern Plains...with particular concern remaining
over New Mexico given the magnitude and the persistence of the
moisture transport into the region and the increasing upper
support from the right entrance region of an upper level jet that
can work in tandem with the complex terrain. HREF neighborhood
probabilities for 24-hour QPF exceeding 10 yr ARI remained robust
enough in New Mexico...and in roughly the same placement as the 06Z
HREF guidance...that the main changes to the previously issued ERO
were mostly across the upper Midwest where models showed a a
southward and westward shift in QPF placement.
Bann
Previous Excessive Rainfall Discussion...
...New Mexico...
Upper level pattern will be in a short transitory phase, but one
that will ultimately lead to a threat of prolonged heavy rainfall
from training convection across much of the terrain in Southern and
Central NM. The massive ridge to the east will flex further as we
head into Tuesday with the higher heights on the western fringes
pushing back west beyond the eastern portions NM. A steady north-
south progression within the mid and upper levels will send
numerous smaller shortwave perturbations poleward with anticipated
motions into the Sacramento's, eventually north into the Sangre de
Cristos by the late-afternoon and evening period on Tuesday.
Moisture remaining parked over the region coupled with the focused
ascent and narrow upslope proxy within the Sacramento Mtns. will
lead to a corridor of heavy convection remaining situated in-of
the terrain. There's a growing consensus within all deterministic
that local topographic effects within this pattern will yield some
significant rainfall potential over areas that are prone to flash
flooding, especially with the burn scars still present near Ruidoso
creating higher runoff capabilities. 00z HREF depicted between 2-3"
of rainfall in just the 12-hr period between 12-00z on Tue/Wed with
precip continuing at the end of the run. Ensemble mean forecast
within the NWP suite was up around 3" for multiple locations with a
large areal coverage of at least 2" within the mean output. These
are generally signals that favor not only flash flooding prospects,
but widespread flash flood concerns with more significant impacts
possible.
The signal for heavy rainfall continues all the way up into the
Sangre de Cristos where the afternoon and evening time frames call
for widespread heavy thunderstorm activity aligned with the ridges
of the southern Rockies. These areas also have burn scar prevalence
that could exacerbate flash flood risks as runoff capabilities are
maximized. Considering the anticipated threat bleeding further
north within the guidance this evening, the previous MDT risk was
expanded northward to encompass those areas within the Sangre de
Cristos and neighboring valleys. The threat for a targeted higher
risk over the Sacramento's is plausible if this signal remains for
another forecast cycle or two. As of now, it is deemed closer to a
high-end MDT risk with the area across the northern Sacramento's
the most susceptible to significant impact potential.
...Central Plains to Midwest...
The pattern across the Plains and Midwest that will bring heavy
rainfall to those areas Monday night into Tuesday morning will
bleed over into the D2 period with ongoing precip likely across
Northeast KS into adjacent areas of NE/MO/IA. Flash flooding
concerns will be ongoing at this time and recent CAMs output is
signaling more rainfall through at least 18z will continue to
plague those same areas. 00z HREF neighborhood probs over the 12hr
period between 12-00z Tue/Wed denote a 40-60% chance of exceeding
2" over areas that will have already seen significant (2-4+")
rainfall the period prior. Rates ~1"/hr are modest within the hi-
res ensemble probability fields as well, a testament to the
persistence in the heavy convective setup in place. There will
finally be less of a concern late in the afternoon as the frontal
progression migrates north the second half of the period, so the
threat will likely be more focused in that area the first half of
the forecast. Still, this is enough for a continued SLGT risk with
higher end risk potential given the period overlap.
The setup the following evening becomes trickier as the entire
evolution comes down to the handling of the mid-level energy riding
northeast out of the Southern Plains into the Central Plains and
Upper Midwest after nightfall. Surface front from the prior period
will eventually hit a roadblock on its southern progression and
flip back to a warm front as it migrates back to the north under
the guide of a potent LLJ generation across the Plains. The
interaction between the front and the energy will create a
secondary convective enhancement that will impact areas further
north than the previous 36 hrs. The lack of overlap may inhibit
significant impacts, however the training threat within the
confines of the boundary may be enough to warrant some higher risk
of flash flooding. The setup is depicted by guidance in the 00-12z
period Wednesday, but position of the heaviest precip is seemingly
all over the place. The threat is certainly there for 2-4" with
locally higher, but specifics still remain sort of muddled. The
SLGT risk prior was adjusted to reflect the ensemble mean QPF
distribution with a heavy precip footprint still located over far
Southeast SD into Southern MN for the period. How far north the
front migrates and handling of the shortwave ejection will
determine exactly where the heaviest precip will occur. Right now,
anywhere within the SLGT risk is fair game, so it's a time frame to
monitor closely.
Kleebauer
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
856 PM EDT Mon Jun 23 2025
Day 3
Valid 12Z Wed Jun 25 2025 - 12Z Thu Jun 26 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
NEW MEXICO, CENTRAL PLAINS AND MIDWEST...
20Z Excessive Rainfall Discussion Update...
Guidance still showed a downward trend in the threat of excessive
rainfall across the country as increasing westerly flow across the
northern tier of states helps to disrupt flow around the upper
ridge anchored over the Southeast US. Even so...there is still
enough of a threat to warrant a high- end Slight across parts of
Minnesota and Iowa and a continuation of a Slight Risk across
portions of New Mexico.
Bann
Previous Excessive Rainfall Discussion...
...New Mexico...
Unlike the prior periods, the D3 is finally the downward trend to
the incessant nature of scattered to numerous thunderstorms that
will plague the state, especially across the Sacramento's and
Sangre de Cristos. Despite the lower coverage anticipated,
scattered thunderstorms are still plausible in the afternoon as
ample heating during prime destabilization window (16-21z) will
yield another threat of thunderstorms across the terrain and
adjacent valleys. Current signals are nowhere near as robust as the
D1/D2 time frames, but with potentially significant impacts prior,
there's a greater threat of truly compromised FFG's leading in
allowing for the bar to be very low for flash flooding. As of now,
the ensemble mean is still highlighting the Sacramento's up into
the I-40 corridor as the main areas of concern. A SLGT risk was
maintained and expanded a bit to encompass the zones of greatest
risk for flash flooding. A targeted higher risk is not out of the
question for the Sacramento's, but will assess in later forecasts
as we monitor how everything evolves leading into the D3.
...Central Plains to Midwest...
Unlike the prior period where there is some uncertainty in the
handling of shortwave energy and frontal positioning, there's a
pretty good consensus brewing on the pattern converging in-of the
Upper Midwest with sights on MN into Western WI as the evolution in
D2 carries over into D3. Mean QPF output via ensembles is running
between 2-4" for an areal average with the maxima positioned across
Southern MN back into adjacent areas of SD/NE to the southwest. Not
one, but two waves of convection will encroach the area with some
spots potentially seeing some significant rainfall (>2") in both
waves which will likely lead to scattered, bordering widespread
flash flood prospects due to the compounding rainfall forecast. NBM
90th percentile QPF is well over 2" across much of the
aforementioned region with some higher totals even extending back
through NE. As of now, it's still a bit early for the higher risks
due to some uncertainty the day prior which could shift the
forecast a bit in either direction (north or south). For now,
maintained a higher end SLGT across a large portion of the Upper
Midwest with the eastern extension pushing all the way out into
Northern WI. A targeted higher risk is certainly in the cards if
this signal remains and consensus grows on the evolution of the
synoptic details.
Kleebauer
Day 3 threat area:
www.wpc.ncep.noaa.gov/qpf/99epoints.txt
