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
417 AM EDT Fri Jun 6 2025
Day 1
Valid 12Z Fri Jun 06 2025 - 12Z Sat Jun 07 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTH-CENTRAL PLAINS, THE LOWER OHIO, LOWER TENNESSEE AND
MIDDLE MISSISSIPPI VALLEYS AND FROM EAST CENTRAL NEW YORK STATE
INTO CENTRAL NEW ENGLAND...
...South-Central Plains.....
There is a strong model signal for another round of organized
convection late Friday afternoon into Friday night/early hours of
Saturday across the south-central plains as additional shortwave
energy is forecast to drop east southeastward from the Central
Rockies into the Central to Southern Plains Friday into Friday
night/early Saturday. The low level flow is expected to again
strengthen into the west to east oriented frontal zone across the
Southern Plains, supporting potential for another round of
organized convection in the vicinity of this front. PW values
along this front will remain above average...2+ standard deviations
above the mean, supporting heavy precip potential. There is fairly
good model consensus for an axis of heavy rains along this front
from far southeast CO/far southwest KS, across much of OK into the
OK/KS/MO/AR border region. The slight risk was drawn to fit the
axis of the highest HREF neighborhood probabilities for 2"+ amounts
and the HREF EAS axis of highest probabilities for 1"+ amounts. The
next round of organized convection will likely track along the same
areas that are currently receiving heavy rainfall late Thursday
evening into early Friday.
...Mid Mississippi Valley, Lower Ohio Valley, Lower Tennessee
Valley...
The lead area of shortwave energy initiating current early morning
convection across the Southern Plains will be pushing toward the
Mid Mississippi Valley, Lower Ohio and Lower Tennessee Valleys
Friday afternoon/evening. Similar to areas upstream along the west
to east oriented frontal zone that extends into the Mid MS, Lower
OH,Lower TN Valley, PW values will be above average, 2+ standard
deviations above the mean. Convection likely to enhance Friday
afternoon/evening ahead of these height falls in the much above
average PW axis, supporting heavy rain potential and localized
flooding issues. A slight risk area was added from the previous
issuance, aligned with where the axis of the highest HREF
neighborhood probabilities for 2"+ amounts and the HREF EAS axis of
highest probabilities for 1"+ amounts are forecast.
...Southern Great Basin into the Central to Southern Rockies...
Not a lot of changes expected to the large scale flow across the
southern Great Basin into the Central Rockies. PW values forecast
to remain above average with additional shortwave energy moving
across the region in the west south west flow aloft. This should
support another day of widespread scattered convection and
localized heavy rain and isolated runoff issues. No significant
changes made to the previous marginal risk area across this region.
...East-central New York into Central New England...
A slight risk area was added for portions of east-central New York
State into central New England from central to southern New
Hampshire, across southeast Vermont, western Massachusetts into
east central NY state. There is good agreement in the last hi res
guidance for enhancing convection in the 1800 UTC Friday to 0000
UTC Saturday period in the axis of above average PW values along
the slow moving frontal boundary draped across this area. The
slight risk was drawn to fit where the axis of high HREF
neighborhood probabilities are for 2 & 3"+ totals. This corresponds
also to where the HREF hourly probabilities for 1"+ totals are
high in the 1800 UTC Friday to 0000 UTC Saturday period.
Oravec
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
417 AM 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...
...Lower Arkansas, Lower Mississippi and Lower Tennessee Valleys..
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. There is some spread with
the qpf axes, but consensus that heavy amounts are possible along
this front. The slight risk area was extended approximately 50m to
100 miles farther to the southeast across northern MS and northern
AL to cover the current model spread.
...East central NY State into Central to Northern 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 east central NY state 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.
Oravec
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
417 AM 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 NORTH TEXAS
INTO SOUTHERN OKLAHOMA...
...North Texas/Southern Oklahoma...
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. 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. The marginal risk area was
extended farther to the northwest into southeast Colorado to cover
the model qpf spread.
...Lower Mississippi Valley into the Southern-Central Appalachians
and Mid-Atlantic...
Broadly diffluent mid to upper level flow expected day 3 ahead of
the height falls pushing out of the Mid to Lower MS Valley, TN and
OH Valley region. With PW values expected to be above average...1.5
to 2+ standard deviations above the mean...widespread scattered
convection possible from the Lower MS Valley, across the Southern
to Central Appalachians and into the Mid-Atlantic. The previous
marginal risk area that was across the South was extended north
through the Southern to Central Appalachians and into the Mid-
Atlantic across the lower FFG values.
Oravec
Day 3 threat area:
www.wpc.ncep.noaa.gov/qpf/99epoints.txt
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
213 AM EDT Fri Jun 6 2025
A trailing frontal boundary draped across the South will provide
focus for numerous showers and thunderstorms through much of next
week. Moderate to locally heavy rainfall is possible and the Days 4
and 5 Excessive Rainfall Outlooks (valid Monday and Tuesday)
highlight this threat with broad marginal risks stretching from the
southern High Plains, across Texas and the lower Mississippi
Valley, and into parts of the Southeast. There remains enough
disagreement in exact placement of heavy rainfall to preclude a
slight risk, but it is possible one will be needed somewhere as
models come more in line, especially for areas that have seen
recent heavy rainfall. The northern portion of this boundary will
be quicker to move through the East, but there could be a heavy
rainfall threat over parts of interior New England and so a
marginal risk area was added to the Day 5/Tuesday ERO tonight.
Elsewhere, precipitation will increase across the Northern Rockies
and into the Northern Plains ahead of a frontal system the second
half of the week.
Much above normal temperatures will continue from the weekend into
early next week for the Northwest, with anomalies of +20-25F
likely. This should equate to a moderate to major heat risk for
parts of this region along with widespread record highs through at
least Monday. Temperatures and heat risk should moderate Tuesday
and Wednesday, but remain slightly above normal. Major to locally
extreme heat risk will continue across South Texas as well into
Monday, becoming much less extreme by Tuesday as an upper level
shortwave moves into the region. By next Thursday and Friday, 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
213 AM EDT Fri Jun 6 2025
A trailing frontal boundary draped across the South will provide
focus for numerous showers and thunderstorms through much of next
week. Moderate to locally heavy rainfall is possible and the Days 4
and 5 Excessive Rainfall Outlooks (valid Monday and Tuesday)
highlight this threat with broad marginal risks stretching from the
southern High Plains, across Texas and the lower Mississippi
Valley, and into parts of the Southeast. There remains enough
disagreement in exact placement of heavy rainfall to preclude a
slight risk, but it is possible one will be needed somewhere as
models come more in line, especially for areas that have seen
recent heavy rainfall. The northern portion of this boundary will
be quicker to move through the East, but there could be a heavy
rainfall threat over parts of interior New England and so a
marginal risk area was added to the Day 5/Tuesday ERO tonight.
Elsewhere, precipitation will increase across the Northern Rockies
and into the Northern Plains ahead of a frontal system the second
half of the week.
Much above normal temperatures will continue from the weekend into
early next week for the Northwest, with anomalies of +20-25F
likely. This should equate to a moderate to major heat risk for
parts of this region along with widespread record highs through at
least Monday. Temperatures and heat risk should moderate Tuesday
and Wednesday, but remain slightly above normal. Major to locally
extreme heat risk will continue across South Texas as well into
Monday, becoming much less extreme by Tuesday as an upper level
shortwave moves into the region. By next Thursday and Friday, most
of the country will be near or within a few degrees of normal.
Santorelli
