Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
833 PM EDT Thu Jun 5 2025
Day 1
Valid 01Z Fri Jun 06 2025 - 12Z Fri Jun 06 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTH-CENTRAL PLAINS...
...Central to Southern Plains...
A broad area of convection this evening across the High Plains
down into Southwest TX will account for 3 areas of focus for the
remainder of the D1 ERO. The most significant of the heavy rain
prospects is currently in the initial phase with a strong
mesocyclone over Southeast CO likely to propagate downstream and
grow upscale with aid from a budding nocturnal LLJ positioned
across KS/OK and points south. 50+ kt deep layer shear will help
maintain a relevant kinematic environment capable of enhancing and
sustaining an eventual MCS moving southeast from Southwestern KS
down through Northern OK during the overnight period, mainly
following the northern edge of a theta_E gradient situated across
the above zone. Despite forward momentum of the eventual MCS,
embedded convective cores will be capable of locally enhanced
rainfall rates of 1-2"/hr with totals likely reaching 2-3" in the
path of the MCS with some 3-5" totals possible over the upwind side
of the complex. For more information on this threat, please see MPD
#372.
Across the Texas Caprock down into Southwest TX, a few supercells
will eventually grow upscale and migrate slowly to the east leading
a trail of heavy rainfall in their paths over the next 3-6 hrs
before waning overnight. The conglomeration over Southwest TX will
maintain the greatest footprint in heavy rain coverage with the
highest flash flood threat likely over the terrain areas
encompassing the Davis and Glass Mtns, and along the I-10 corridor
situated in the Stockton Plateau. Multiple flash flood warnings are
already in effect for those areas with totals likely breaching 2"
in several areas across the above zones by the end of the event.
These setups can be tricky and prolonged heavy rain threats beyond
current CAMs inference are unfortunately common as cold pool
convergence can maintain cell clustering longer than normal.
The zone across CO/KS/OK maintained the previous SLGT risk with a
minor extension on the western flank of the risk. The MRGL was kept
for much of West TX with the best flash flood risks likely over the
Caprock of TX into Northwest TX near the Red River, and over
Southwest TX within the Davis/Glass Mtn area and adjacent Stockton
Plateau.
...Southern Great Basin into the Central Sierras...
Elongated surface trough and attendant surface low across the
Southern Sierras will maintain a positively buoyant environment
within the confines of the Sierras down into the Southern Great
Basin (See MPD #373 for details on the setup across the Great Basin).
Visible satellite over the West indicates two distinct surface
boundaries bisecting Southern NV into Southern UT and across
Northern AZ to the Colorado River Basin at the CA/AZ border.
Mesoanalysis across the area indicates a relative instability
maximum within that portion of the Desert Southwest with SBCAPE
~500-1000 J/kg aligned over Northwestern AZ into Southern NV, a
stripe over the Central Sierra's where locally heavy rainfall is
already producing some flash flood concerns in the Foothills. The
threat for convection lingering between 01-04z is pretty high when
assessing hourly CAMs, and projects well considering the
environment in place. This is a signature typically seen as one
that can prolong heavy rain potential over the region, an area very
susceptible to flash flooding concerns with stronger convective
cores. A MRGL risk was maintained over the Southern Great Basin
with an extension up through the Central Sierra's given the local
instability maximum situated over the area with ongoing
thunderstorms.
..Ohio Valley into the Northern Mid Atlantic...
Area convection continues to fire within the terrain across WV and
Western PA with a tongue of instability remaining along and ahead
of a cold front analyzed from the Ohio Valley into the Northeast.
Shear remains confined over NY State with less deep layer shear as
you move south leading to the strongest thunderstorm activity
situated across Southern NY state. A quick 1-2" will be plausible
within the environment in place this evening with a trend in less
coverage anticipated after 03z. A shortwave currently analyzed over
the Mid-Mississippi Valley will slide eastward overnight with a
better dynamical input positioned across the Eastern Ohio Valley
early tomorrow morning as CAMs initiate another round of convection
across OH and Western PA after 09z. Despite a weaker surface based
instability prog over the area, there's enough of a combination of
boundary layer buoyancy and mid-level ascent to enhance area
convection capable of isolated flash flood potential during the
early morning hours. As a result, the previous MRGL risk was
maintained within that zone of Southern OH, extending northeast
into Southern NY State with an alignment closely tied to the cold
front progression this evening.
Kleebauer
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
850 PM EDT Fri Jun 6 2025
Day 1
Valid 01Z Sat Jun 07 2025 - 12Z Sat Jun 07 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS AND OHIO VALLEY...
...Texas Caprock...
Multiple supercells will continue to plague the area within WFO
Lubbock, TX CWA bounds with cells originally forming within the
Caprock and moving eastward within the mean layer flow. Sufficient
buoyancy and shear across the Southern High Plains will maintain
severe thunderstorm posture for at least another 2-4 hours before
any convection begins to collapse, or even induce cell mergers in
the case of the activity between the NM/TX state lines through
Northwest TX. Rainfall rates between 2-3"/hr with intra-hour rates
up to 5"/hr will lead to flash flood concerns over an area still
recovering from yesterdays barrage of rainfall from a similar
convective evolution. The previous SLGT was generally maintained
with a minor expansion to the northern edge to encompass left-
moving supercells that are making headway towards the southern
portion of the Panhandle.
...Southern Plains to Ozarks...
A repeat of the pattern last evening with multiple mesocyclones
currently situated over the Southeast CO Front Range will shift
southeast with general motion with the upwind propagation vector. A
distinct split heavy rain axis will transpire across the eastern TX
Panhandle into OK with another across the Northern half of OK into
Southern KS as the cells eventually merger into a large MCS that
will propagate southeast towards Eastern OK into the Northwest AR
Ozarks by the end of the forecast. Heavy rainfall between 2-4" with
locally as high as 5" are forecast within the confines of the
northern half of the expected complex, crossing through a region
with saturated antecedent grounds thanks to the previous mornings
MCS that hit the same areas as expected tonight. Anywhere from the
I-40 corridor on north will have the potential for flash flooding
due to the MCS with a high-end SLGT risk positioned over the OK/KS
border where 1/3/6 hour FFG's have been significantly degraded from
previous activity last night into this morning. The SLGT risk was
expanded on the northern edge from previous update to attribute to
the latest heavy QPF footprint on the upwind side of the expected
MCS development this evening.
...Ohio Valley...
Large cluster of thunderstorms capable of 1-2"/hr rates will
continue to maneuver eastward through the Ohio River Basin down
into KY with a secondary batch of convection moving through TN with
a few stronger cores. Shortwave energy associated with the cell
conglomeration will motion eastward into the Central Appalachian
Front leading to scattered heavier convection to shuffle through
the Ohio River basin and KY into WV overnight. Signals for a few
heavier cells over the terrain of Eastern KY into WV have been
steady in the CAMs through the course of the day with some areas
already been affected by previous heavy rain output during the D1
time frame. FFG's remain relatively low in those areas from all the
prior precip with some areas likely to reach over 2" in 24 hrs from
all the convective impact in the time period. Considering the
threat for heavy precip in back-to-back posture, a SLGT risk was
maintained over KY and expanded to the east to include WV where
hourly CAMs have been more aggressive with heavier QPF signals in
the latest iterations.
...West Texas...
Sufficient surface based instability on the order of 2000-4000 J/kg
has allowed for scattered thunderstorms development across
Southeast NM down through the Upper Trans Pecos of TX. Mean storm
motions of 15-20 kts to the east should maintain relatively steady
forward momentum of convection through the evening, but any strong
convective core could throw out an easy 1-2" total within a short
period of time leading to localized flash flood concerns over
Southeast NM, Northwest Permian Basin, down through the mountains
of Southwest TX. A MRGL risk remains for those areas, but was
trimmed on either side to fit a more narrow axis where storms could
survive before hitting a more capped environment near the Pecos
river and points east.
Kleebauer
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
850 PM EDT Fri Jun 6 2025
Day 2
Valid 12Z Sat Jun 07 2025 - 12Z Sun Jun 08 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE LOWER
ARKANSAS VALLEY, LOWER MISSISSIPPI VALLEY INTO THE LOWER TENNESSEE
VALLEY...
...Eastern Oklahoma and Northeast Texas to Central/Northern
Alabama...
The second round of height falls moving into the Central
to Southern Plains day 1 will continue to push east southeast
toward the Mid to Lower MS Valley, OH and TN Valleys during day 2.
Upper difluence is forecast to be well defined Saturday into
Saturday night/early Sunday in an axis of above average PW values
that will remain along the west to east oriented frontal boundary
across these areas. This should support potential for another round
of organized convection along this front as well as near a well-
defined mid-level circulation passing to the north into the Ohio
Valley. There is some spread with the qpf axes, but consensus that
heavy amounts are possible. The inherited Slight Risk area was
shifted a bit south and removed from most of TN given southern
trends with the early morning MCS and related redevelopment along
the associated lingering outflow boundary through the early evening
into northeast TX.
...Middle Mississippi and Ohio Valleys...
Mid-level wave ejecting out of the central Plains Saturday morning
will continue to push eastward across the Ohio Valley. This
feature will aid in increased moisture return and shear to provide
for scattered to numerous showers and thunderstorms. The inherited
Marginal Risk was expanded northward to capture this trend of more
precipitation attached to the mid-level low. A Slight Risk may be
necessary across the Ohio Valley from southern IL to northern KY
and southern OH, but this area is conditional on whether enough
instability can build ahead of the mid-level shortwave pushing
eastward. Should guidance come into better agreement this upgrade
may be needed, with latest HREF probs for at least 2"/6-hr up to
40%. Antecedent conditions are also rather wet, so that will need
to be considered as well with current convection for the next
overnight update.
...Northeast PA through New England...
Another round of convection possible early day 2 along the frontal
boundary pushing through the northeast as a sharpening northern
stream trof pushes eastward across northern NY into New England.
The HREF neighborhood probabilities for the 12 hour period from
1200 UTC Saturday to 0000 UTC Sunday, are high along this front for
1 and 2"+ amounts. The previous marginal risk area was extended
farther west into northeast PA to cover these higher 12 hour
probabilities. There may need to be an upgrade to the risk level in
future issuances depending upon where the heavy rains occur during
day 1.
Snell/Oravec
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
850 PM EDT Fri Jun 6 2025
Day 3
Valid 12Z Sun Jun 08 2025 - 12Z Mon Jun 09 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS NORTHERN
TEXAS AND SOUTHERN OKLAHOMA...
...Southern Plains to the Southeast...
Additional shortwave energy likely to push east southeastward late
Sunday afternoon/evening from the lee of the Central to Southern
Rockies into the Southern Plains under the influence of a much
stronger upper level low centered over the north-central United
States. This will again re- strengthen the low level flow into the
west to east oriented front forecast to remain across the Southern
Plains, supporting another round of organized convection along the
front. There is fairly good agreement on the day 3 qpf axes in the
models. Resulting in good continuity with the slight risk area
with only a subtle expansion and south shift where widespread rainfall
amounts of 2-4" are expected and higher amounts possible.
Additional thunderstorm activity is expected from early morning
convection and afternoon redevelopment along the frontal boundary
through the Southeast, with mostly isolated flash flooding
concerns.
...Central Appalachians and Upper Ohio Valley...
Meanwhile, the mid-level wave progressing across the Ohio Valley on
day 2 will continue into the central Appalachians and northern
Mid-Atlantic while interacting with a lingering frontal boundary.
This will produce additional areas of scattered areas of convection
and the potential for isolated instances of flash flooding within
typically sensitive terrain. There remains higher than average
uncertainty regarding the speed of this system, which could impact
the eventual flash flood risk area.
Snell/Oravec
Day 3 threat area:
www.wpc.ncep.noaa.gov/qpf/99epoints.txt
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
214 AM EDT Sat Jun 7 2025
A trailing frontal boundary draped generally west to east across
the South will provide focus for numerous showers and thunderstorms
through much of next week. The Days 4 and 5 Excessive Rainfall
Outlooks (valid Tuesday and Wednesday) reflect this. For Day 4, a
very broad marginal risk stretches all the way from the southern
Plains/High Plains to the Gulf Coast states. Models are starting to
show better consensus on potentially flooding rains impacting
central Texas, but still with enough uncertainty to preclude a
slight risk at this time. For Day 5, there is better agreement on
heavy to excessive rainfall again in central Texas, and combined
with rainfall in the same region on Day 4, went ahead and added a
slight risk to the ERO for tonight. By Thursday, this boundary
looks to lift northward with heavy rainfall potential moving into
the central Plains/mid-Mississippi Valley which has been wet as of
late and will need to be monitored for flooding concerns later this
week.
The northern portion of this boundary should be quicker to move
through the East, but heavy rainfall is possible along the boundary
amidst ample moisture and instability and favorable upper level
dynamics. A marginal risk for the interior Northeast remains on the
Day 4 ERO. Elsewhere, additional short wave energy interacting
with a frontal boundary across the northern tier will bring showers
and storms from parts of the northern Rockies into the Upper
Midwest. Marginal risk areas were added to the Day 5/Wednesday ERO
tonight for parts of Montana and also South
Dakota/Minnesota/Wisconsin.
Much above normal temperatures will continue into early next week
for the Northwest, with anomalies of +20-25F likely to continue on
Tuesday. This should equate to a moderate to major HeatRisk for
parts of this region along with widespread record highs.
Temperatures and HeatRisk should by Wednesday, but remain slightly
above normal, including farther south into the central Great Basin.
Short range heat across South Texas should be much less extreme by
Tuesday as an upper level shortwave moves into the region. By next
Thursday-Saturday, most of the country will be near or within a
few degrees of normal.
Santorelli
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
214 AM EDT Sat Jun 7 2025
A trailing frontal boundary draped generally west to east across
the South will provide focus for numerous showers and thunderstorms
through much of next week. The Days 4 and 5 Excessive Rainfall
Outlooks (valid Tuesday and Wednesday) reflect this. For Day 4, a
very broad marginal risk stretches all the way from the southern
Plains/High Plains to the Gulf Coast states. Models are starting to
show better consensus on potentially flooding rains impacting
central Texas, but still with enough uncertainty to preclude a
slight risk at this time. For Day 5, there is better agreement on
heavy to excessive rainfall again in central Texas, and combined
with rainfall in the same region on Day 4, went ahead and added a
slight risk to the ERO for tonight. By Thursday, this boundary
looks to lift northward with heavy rainfall potential moving into
the central Plains/mid-Mississippi Valley which has been wet as of
late and will need to be monitored for flooding concerns later this
week.
The northern portion of this boundary should be quicker to move
through the East, but heavy rainfall is possible along the boundary
amidst ample moisture and instability and favorable upper level
dynamics. A marginal risk for the interior Northeast remains on the
Day 4 ERO. Elsewhere, additional short wave energy interacting
with a frontal boundary across the northern tier will bring showers
and storms from parts of the northern Rockies into the Upper
Midwest. Marginal risk areas were added to the Day 5/Wednesday ERO
tonight for parts of Montana and also South
Dakota/Minnesota/Wisconsin.
Much above normal temperatures will continue into early next week
for the Northwest, with anomalies of +20-25F likely to continue on
Tuesday. This should equate to a moderate to major HeatRisk for
parts of this region along with widespread record highs.
Temperatures and HeatRisk should by Wednesday, but remain slightly
above normal, including farther south into the central Great Basin.
Short range heat across South Texas should be much less extreme by
Tuesday as an upper level shortwave moves into the region. By next
Thursday-Saturday, most of the country will be near or within a
few degrees of normal.
Santorelli
