Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
826 PM EDT Wed Jun 4 2025
Day 1
Valid 01Z Thu Jun 05 2025 - 12Z Thu Jun 05 2025
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN HIGH PLAINS, MID-MISSISSIPPI VALLEY INTO THE GREAT LAKES,
AND THE IMMEDIATE CAROLINA COAST...
....Southern High Plains...
Mid-level shortwave will exit out of the Southern Rockies with
convection maintaining organization as it crosses over Eastern NM
into the TX Panhandle and adjacent Caprock. Sufficient buoyancy and
ascent within the proxy of a modest 40-45kt speed max will be
enough to maintain the convective output currently migrating across
North-Central NM. Upscale growth within the cluster is anticipated
with the assistance of a modest LLJ component feeding into the
convection on its expected path. A few other pockets of convection
will be plausible across portions of Southeast CO and over the High
Plains down through Southeast NM. Totals of 1-2" with locally
higher are forecast leading to isolated flash flood concerns in any
given area with emphasis on more urbanized zones due to higher
runoff potential. A MRGL risk remains for the above zones.
...Mid-Mississippi through the Great Lakes...
Continued migration of several weak shortwave impulses over top a
quasi-stationary boundary extending from OK up into MI will lead to
more convective clusters moving over areas of MO/IL/IN and
eventually MI as we move into the morning. A few weak surface lows
have been analyzed within the front with each of the lows expected
to move northeast along the front with the boundary slowly trudging
eastward. Overlap of rainfall into areas that already saw 1-3" of
rain will lead to some prospect of flash flooding in the above
zones with a lesser chance outside those areas, but still within
the lower bound of the MRGL risk threshold. 18z HREF neighborhood
probs were pretty robust for >3" in places across IL/MO, but
assessment of those probabilities led to a bias on the high side
with some of the older CAMs guidance (ARW family) that exacerbated
the output. Considering the progression of the precip pattern, the
previous SLGT was removed with the MRGL risk favored for areas from
Northeast AR up through South-Central and Southeastern MI and
points in-between.
...Carolina Coast...
Inverted trough analyzed off the SC coast will continue to plague
the immediate coastal areas with the heaviest precip footprint
currently just offshore of CHS with a migration to the north.
Strong low-level convergence signature will remain over the
northern periphery of a weak surface reflection organizing over the
Southeast coast. A band of heavier rain will occur between CHS up
through MHX with the greatest opportunity for heavier rates and
flash flooding likely locked to the coastal plain and more prone
urban areas. PWATs running near climatological peak across that
area (2-2.2" expected) depicts a moisture rich profile capable of
locally enhanced rates and totals that could easily reach 2-3" with
isolated to 4" in a few of the harder hit areas. Right now, that
chance seems to be more north than what was alluded to earlier in
the D1 with places from Myrtle Beach through Wilmington to
Morehead City the more likely to see the heaviest rainfall. The
sandier soils will help keep the worst of the potential at bay, so
the threat is more relegated to the MRGL risk category when
assessing trends. As a result, the previous SLGT risk was dropped
with a MRGL across portions of the immediate SC and Southeastern NC
coast.
Kleebauer
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
405 AM EDT Thu Jun 5 2025
Day 1
Valid 12Z Thu Jun 05 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...
Shortwave energy embedded in the west southwesterly mid to upper
level flow across the Central to Southern Plains will support
additional organized convection late Thursday afternoon into
Thursday night/early Friday morning across portions of the Central
to Southern Plains. The low level southerly flow expected to
strengthen Thursday afternoon into the northward moving warm front
across the Southern Plains, igniting convection across southeast
Colorado, with this activity then enhancing as it treks east
southward across southern KS and northern OK. The previous broad
slight risk area was narrowed to better align with the higher HREF
neighborhood probabilities for 2 and 3"+ amounts and where the HREF
EAS probabilities for 1"+ amounts were highest, indicating where
hi res guidance was in better agreement. South of this west to east
slight risk area, there was less agreement on convective placement
across western TX. The previous slight risk area was reduced to
marginal given this and higher FFG values.
Upstream across the Southern Great Basin into the Southern to
Central Rockies...no changes made to the previous slight risk
area. PW values expected to remain well above average from southern
NV into northern AZ, Southern UT and western CO, supporting
another day of widespread scattered convection, locally heavy rains
and isolated runoff issues.
..Lower Lakes, OH Valley into the Mid to Lower MS Valley...
PW values also expected to remain above average in the vicinity of
the nearly stationary frontal boundary stretching from the lower
Lakes, southwest into the OH Valley and Mid to Lower MS Valley. A
broad marginal risk area was maintained from previous issuances for
localized heavy rainfall and isolated runoff issues. The previous
marginal risk area was narrowed to better reflect latest model
consensus on the moderate to locally heavy qpf axis.
...Coastal SC into eastern NC...
A weak surface low, accompanied by an axis of above average PW
values will push northeast along the SC/NC coasts day 1. The
latest model consensus is for the axis of the heaviest
precipitation to remain offshore, indicated by fairly high HREF EAS
probabilities for 1, 2 and 3"+ totals off the NC coast. Given
this, the previous slight risk area over the central NC coast was
removed. There is consensus for an inland max day 1 qpf across
southeast NC. The HREF neighborhood probabilities are fairly high
for 2 and 3"+ amounts, although there is not good overlap in
placement as EAS probabilities are much lower for these values.
Considered a slight risk here, but with FFG values high and low EAS
probabilities for the 2 and 3"+ amounts, the risk was kept at
marginal.
Oravec
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
405 AM EDT Thu Jun 5 2025
Day 2
Valid 12Z Fri Jun 06 2025 - 12Z Sat Jun 07 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF
OKLAHOMA INTO THE KANSAS, OKLAHOMA, MISSOURI, ARKANSAS BORDER
REGION...
...Oklahoma into the OK/KS/MO/Ar border area...
Another round of shortwave energy forecast to drop east
southeastward from the Central Rockies into the Central to Southern
Plains Friday into Friday night/early Saturday. This will support
potential for another round of organized convection in the vicinity
of the west to east oriented frontal zone. 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 across
much of OK into the OK/KS/MO/AR border region. Only some slight
changes to the previous slight risk area to reflect this qpf axis
consensus.
...Southern Great Basin into the Central to Southern Rockies...
Not a lot of changes expected to the large scale flow from day 1
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. The marginal risk
was extended back across these areas to be more similar to the day
1 period given the similar overall conditions day 2.
...Mid MS Valley, OH Valley into New England...
Similar to the day 1 period, an axis of above average PW values
will stretch along the slow moving front stretching from the Mid MS
Valley, OH Valley into New England. There is good model consensus
on a broad region of moderate to locally heavy precip amounts along
this front. Only some minor changes to reflect the latest model
qpf axis consensus made to the previous broad marginal risk area
across these regions.
Oravec
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
405 AM EDT Thu Jun 5 2025
Day 3
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...
The second round of height falls moving into the Central to
Southern Plains day 2 will continue to push east southeast toward
the Mid to Lower MS Valley, OH and TN Valleys. 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 previous slight risk area was expanded eastward
considerably from eastern OK, across much of AR, western TN and
northern MS.
...Northern New England...
A sharpening northern stream trof will push surface low pressure
across northern New England on Sunday. There is fairly good model
consensus for moderate to locally heavy precip totals across
northern New England. Only some slight changes to the previous
marginal risk area, extending it into all of northern Maine to
cover the model qpf spread.
Oravec
Day 3 threat area:
www.wpc.ncep.noaa.gov/qpf/99epoints.txt
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
256 PM EDT Wed Jun 4 2025
A frontal system will be working through the Northeast at the
start of the period Saturday, with above average moisture (likely
from the Gulf and Atlantic) and instability pooling along and ahead
of it. This should produce some convection possibly with heavy
rain rates over an inch per hour that could cause flash flooding
concerns over typically sensitive areas like terrain in the
Northeast. Thus a Marginal Risk is in place in the Day 4/Saturday
ERO in eastern New York into northern New England. This trend was
farther north than than the previous outlook showed.
This front will stretch back through the Lower Ohio/Tennessee
Valleys, Lower Mississippi Valley, and into the southern Plains.
Ample moisture and high instability is likely across this southern
tier with upper level support at the base of the trough. Rain and
thunderstorms are likely to be widespread with these parameters in
place. The Storm Prediction Center continues to show the potential
for severe weather Saturday across the south-central Plains east
into the Southeast. Meanwhile there is a threat for flash flooding
in much the same areas, but perhaps reaching the southern
Appalachians. The Day 4/Saturday ERO indicates a Marginal Risk,
with an embedded Slight along the Red River into the Ark-La-Tex
where convection may be ongoing Saturday morning, with another
round Saturday night. This Slight was shifted just a bit south
compared to the previous issuance per newer guidance. Did think it
was best to break the Day 4 Marginal Risk that previously stretched
across the central/northern Appalachians and remove those areas,
as rain there is generally expected to be less than half an inch
and not cause flash flooding concerns.
Into Sunday, the front will progress more quickly offshore of the
Northeast, but linger across the southern tier, pressing slightly
southward especially in the Southeast. A Day 5 Marginal Risk is in
place across the Lower Mississippi Valley and Southeast, with an
expansion back west across the southern Plains where models
indicate yet another MCS. Will continue to monitor if/how heavy
rain overlaps with previous days, with the ground being more
sensitive in areas where there has already been heavy rain ,
leading to enhanced flooding concerns. In other words, eventual
upgrades to Slight Risks are certainly possible especially where
antecedent conditions allow for it, and if/where models converge on
placement of heavy rain rates.
Meanwhile, another frontal system will track across the
Midwest/Great Lakes for some modest rain there over the weekend,
reaching the Northeast by Monday and Tuesday. The current forecast
continues to show the leading front dissipating while this
secondary front becomes dominant. The second front settling south
will once again promote rain and thunderstorms across the southern
Plains and Southeast through the first half of next week as the
moisture and instability lingers.
The trough aloft centered in the east-central U.S. will generally
lead to average to slightly below average temperatures there.
However, southern Texas will be a few degrees above already hot
averages, reaching well into the 100s with heat indices possibly
above 110F. But the largest temperature anomalies will be across
the Northwest U.S. through the weekend into early next week
underneath mean upper ridging. Temperatures are forecast to be 15
to 25 degrees above average across much of the Northwest, with
highs reaching well into the 90s in interior areas. Even cities
like Seattle look to reach the mid to upper 80s. Above normal
temperatures will stretch into the central Great Basin, and the
Desert Southwest can expect temperatures well into the 100s to 110
degrees. For safety information, see weather.gov/heat.
Tate
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
256 PM EDT Wed Jun 4 2025
A frontal system will be working through the Northeast at the
start of the period Saturday, with above average moisture (likely
from the Gulf and Atlantic) and instability pooling along and ahead
of it. This should produce some convection possibly with heavy
rain rates over an inch per hour that could cause flash flooding
concerns over typically sensitive areas like terrain in the
Northeast. Thus a Marginal Risk is in place in the Day 4/Saturday
ERO in eastern New York into northern New England. This trend was
farther north than than the previous outlook showed.
This front will stretch back through the Lower Ohio/Tennessee
Valleys, Lower Mississippi Valley, and into the southern Plains.
Ample moisture and high instability is likely across this southern
tier with upper level support at the base of the trough. Rain and
thunderstorms are likely to be widespread with these parameters in
place. The Storm Prediction Center continues to show the potential
for severe weather Saturday across the south-central Plains east
into the Southeast. Meanwhile there is a threat for flash flooding
in much the same areas, but perhaps reaching the southern
Appalachians. The Day 4/Saturday ERO indicates a Marginal Risk,
with an embedded Slight along the Red River into the Ark-La-Tex
where convection may be ongoing Saturday morning, with another
round Saturday night. This Slight was shifted just a bit south
compared to the previous issuance per newer guidance. Did think it
was best to break the Day 4 Marginal Risk that previously stretched
across the central/northern Appalachians and remove those areas,
as rain there is generally expected to be less than half an inch
and not cause flash flooding concerns.
Into Sunday, the front will progress more quickly offshore of the
Northeast, but linger across the southern tier, pressing slightly
southward especially in the Southeast. A Day 5 Marginal Risk is in
place across the Lower Mississippi Valley and Southeast, with an
expansion back west across the southern Plains where models
indicate yet another MCS. Will continue to monitor if/how heavy
rain overlaps with previous days, with the ground being more
sensitive in areas where there has already been heavy rain ,
leading to enhanced flooding concerns. In other words, eventual
upgrades to Slight Risks are certainly possible especially where
antecedent conditions allow for it, and if/where models converge on
placement of heavy rain rates.
Meanwhile, another frontal system will track across the
Midwest/Great Lakes for some modest rain there over the weekend,
reaching the Northeast by Monday and Tuesday. The current forecast
continues to show the leading front dissipating while this
secondary front becomes dominant. The second front settling south
will once again promote rain and thunderstorms across the southern
Plains and Southeast through the first half of next week as the
moisture and instability lingers.
The trough aloft centered in the east-central U.S. will generally
lead to average to slightly below average temperatures there.
However, southern Texas will be a few degrees above already hot
averages, reaching well into the 100s with heat indices possibly
above 110F. But the largest temperature anomalies will be across
the Northwest U.S. through the weekend into early next week
underneath mean upper ridging. Temperatures are forecast to be 15
to 25 degrees above average across much of the Northwest, with
highs reaching well into the 90s in interior areas. Even cities
like Seattle look to reach the mid to upper 80s. Above normal
temperatures will stretch into the central Great Basin, and the
Desert Southwest can expect temperatures well into the 100s to 110
degrees. For safety information, see weather.gov/heat.
Tate