Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
251 AM EDT Sun May 25 2025

Valid 12Z Sun May 25 2025 - 12Z Tue May 27 2025

...There is a Moderate Risk of excessive rainfall over parts of the
Southern Plains and the Lower Mississippi Valley on Sunday...

...There is a Slight Risk of excessive rainfall over parts of the Southern
Plains and the Lower Mississippi/Tennessee Valleys on Monday...

...There is an Enhanced Risk of severe thunderstorms over parts of the
Southern Plains on Sunday...

...There is a Slight Risk of severe thunderstorms over parts of the
Southern Plains on Monday...

A quasi-stationary front extending from the Southeast to the Southern
Plains and Central Rockies will remain through Tuesday. Moisture flowing
northward out of the Gulf of America will overrun the boundary, creating
showers and thunderstorms with heavy rain over parts of the Southern
Plains and Lower Mississippi/Tennessee Valleys. Therefore, the WPC has
issued a Moderate Risk (level 3/4) of excessive rainfall over parts of the
Southern Plains and Lower Mississippi Valley through Monday morning.
Numerous flash flooding events are possible. In addition, many streams may
flood, potentially affecting larger rivers.

Furthermore, there is a risk of severe thunderstorms. Therefore, the SPC
has issued an Enhanced Risk (level 3/5) of severe thunderstorms over the
Southern Plains through Sunday morning. The hazards associated with these
thunderstorms are frequent lightning, severe thunderstorm wind gusts,
hail, and a few tornadoes. However, there is an increased risk of severe
thunderstorm wind gusts of 65 knots or greater and hail, two inches or
greater, over the Southern Plains.

Additionally, showers and thunderstorms will develop over parts of the
Southeast and southern mid-Atlantic on Sunday.

On Monday, the risk of showers and thunderstorms with heavy rain continues
over parts of the Southern Plains, the Lower Mississippi Valley, and the
Tennessee Valley. Therefore, the WPC has issued a Slight Risk (level 2/4)
of excessive rainfall over parts of these areas from Monday through
Tuesday morning. The associated heavy rain will create mainly localized
areas of flash flooding, with urban areas, roads, small streams, and
low-lying areas the most vulnerable.

Likewise, severe thunderstorms will continue over parts of the Southern
Plains. Therefore, the SPC has issued a Slight Risk (level 2/5) of severe
thunderstorms over parts of the Southern Plains from Monday through
Tuesday morning. The hazards associated with these thunderstorms are
frequent lightning, severe thunderstorm wind gusts, hail, and a few
tornadoes. However, there is an increased risk of hail, two inches or
greater, over parts of the region.

Further, showers and thunderstorms will develop over parts of the
Southeast and Mid-Atlantic on Monday into Tuesday.

Meanwhile, a front approaches the Pacific Northwest on Sunday, moving
inland to the Northern Rockies/Northern Intermountain Region and into
parts of the Great Basin by Tuesday. The system will produce light rain
over parts of the Pacific Northwest Sunday evening into Monday. On Monday,
the rain will move slowly into the Northern Rockies/Northern Intermountain
Region and end over the Northwest. Furthermore, an upper-level low will
develop over the Upper Midwest Monday evening into Tuesday, creating light
rain over parts of the Northern Plains.

Elsewhere, upper-level energy over the Northeast will produce scattered
rain and showers over the Northeast through late Monday.


Ziegenfelder


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
253 AM EDT Sun May 25 2025

Valid 12Z Wed May 28 2025 - 12Z Sun Jun 01 2025


...Overview...

This medium range period begins midweek with a slow to progress
upper level pattern lingering over the lower 48, with split flow to
include a couple of embedded cutoff lows. A northern stream low
will meander over the north-central U.S. and Midwest this week
while an offshore southern stream low will only gradually approach
the Southwest U.S. as upper ridging builds heat over the West. The
northern stream low should gain momentum heading into next weekend
as it tends to sync into amplified upper level troughing. This
pattern will result in a period with areas of wet unsettled weather
to focus from the south-central U.S. to the East/Southeast U.S.
this
week. Meanwhile, a series of Pacific frontal approaches sluggishly
toward the Pacific Northwest may offer some modest coastal rains
chances into later week.

...Guidance/Predictability Assessment...

Guidance still offers a reasonably similar larger scale pattern
evolution for this upcoming week in overall slow to transition
flow. However, complex system interactions have led to an increase
in smaller scale flow variances through medium range time scales,
especially eminating from north-central U.S. closed low evolution.
Accordingly, favor a better compatible 18 UTC GEFS mean and 12 UTC
ECMWF/Canadian ensemble means blend along with best clustered model
guidance from the 12 UTC ECMWF and to a lesser extent the 12 UTC
Canadian to add reasonable detail. The composite seems to mitigate
smaller scale issues consistent with individual predictability.
WPC product continuity is well maintained, with a solution in line
with favorable 00 UTC guidance trends of the ECMWF/Canadian/UKMET.

...Weather/Hazards Highlights...

A series of waves will develop along a frontal system eminanting
from the South. These lows will slowly progress downstream to
focus locally enhanced rains, while pooled moisture fuels local
downpours near a trailing front back across the South. Downpour
chances will be protracted with advent and reinforcement from
Midwest cyclo/frontogenesis from northern stream energies that lead
into a later period amplified upper trough signature over a
cooled/unsettled East. A Day 4/Wednesday WPC Excessive Rainfall
Outlook (ERO) Marginal Risk area shows best focus may linger over
the eastern Mid-Atlantic with lead low passage. The Day 4/5 EROs
also offer a Marginal Risk area back over the south-central
Plains/Rockies and Lower Mississippi Valley given induced return
flow and instability/upper support, with the active pattern likely
to linger later week to monitor, especially over the moist South.

In the West, a building upper ridge will lead to an expanding area
of heat from the Intermountain West into the West Coast states
this week, with temperatures rising upwards to 10 to 15+ degrees
above normal. This in particular may lead to a hazardous heat focus
for the California Central Valley late week/next weekend.

Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
323 AM EDT Sun May 25 2025

Valid 00Z Mon 26 May 2025 - 00Z Mon 02 Jun 2025

Models and ensembles generally agree that moderate to breezy
trades are likely to persist through the holiday weekend, albeit
with moisture levels and showers gradually decreasing as a trough
aloft to the northeast slowly slides away. Trade winds may weaken
slightly to moderate levels for much of the regular workweek in
this drier pattern, but there is an increasing guidance signal for
a return flow of deeper moisture by late week to monitor.

Schichtel

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
852 PM EDT Sat May 24 2025
Day 1
Valid 01Z Sun May 25 2025 - 12Z Sun May 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE OZARKS AND
MID-SOUTH...

01Z Excessive Rainfall Discussion...
No fundamental shift in forecast reasoning from previous outlook.
Did expand the Marginal and Slight risk areas a bit westward given
the uncertainty about where the storms will fire that build
southeast into the outlook areas. The expectation is that the
convection will grow in areal coverage and intensity once the low
level jet develops and rides north of a quasi-stationary boundary
draped across the Plains later tonight. Also extended the Marginal
risk area southwest into Texas along and ahead of storms that were
developing along/near the dryline within a very unstable
environment. Given a slow westward motion noted on
satellite...any downpours may last long enough to produce isolated
instances of flooding (mainly in regions of poor drainage).

Bann

...Previous Excessive Rainfall Discussion...


...South-Central Plains through Mid-South into the Southeast...

16Z Update...
Organized mesoscale systems continuing this morning over eastern
OK, central AR and some activity over northern MS/AL. This activity
is waning with IR satellite imagery depicting warming trends.

There is general agreement among 12Z CAMs for afternoon
redevelopment over southeast KS/northeast OK over the Plains and
propagating southeast over eastern OK, southeast MO and much of AR
which all saw heavy rain over the past day (except for northwest AR
which was largely avoided). These storms should once again produce
heavy rainfall rates, per 12Z HREF with probabilities for 3 inches
in three hours and RAP guidance renewing 1.75 inch PW on the
continued southerly flow from the Gulf. Extra caution should be
given through the greater Ozarks region given this holiday weekend
with greater activity in and around flash flood prone areas.

Frontal convergence farther east through northern GA will allow
scattered heavy development where the Marginal Risk was expanded
through.


...Central High Plains...

Moist low level easterly flow maintains PWs of 0.75 to 1 inch (2+
standard deviations above normal), which along with mid-level
energy and right entrance region jet forcing, will continue to
support storm development with locally heavy rainfall over the High
Plains with afternoon development east from the Laramie Mountains
and Front Range. Slow storm motions could allow local rainfall of
2 to 3 inches. The Marginal Risk was expanded over western Neb and
southeast WY with some shrinking along the I-25 corridor in CO.

Jackson

Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
852 PM EDT Sat May 24 2025
Day 2
Valid 12Z Sun May 25 2025 - 12Z Mon May 26 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FROM
CENTRAL OKLAHOMA INTO THE OZARKS...

...Southern Plains through the Ozarks and Mid-South...

21Z Update...
Expanded the Moderate Risk south and west to include central
Oklahoma and more of northwest Arkansas.

Convective activity tonight looks to focus along a broad swath over
southern KS, eastern OK and southern MO and shift southeast early
Sunday over eastern/central OK and northern AR where a stationary
front is likely to remain. Strengthening southerly winds ahead of
an amplified trough moving across the Southwest will support
deepening moisture along the front and an increasing threat for
heavy rainfall back across southwestern Oklahoma and along the Red
River Valley. With these repeating events expected to bring
additional rain of 2 to 4 inches with locally higher, the Slight
Risk was expanded to include much of OK as well as more of AR.

While the better organized and heaviest amounts are expected to
center over Oklahoma through the Ozarks, there is the potential
for localized heavy amounts and isolated flash flooding to spread
east along the frontal boundary through the Tennessee Valley,
north Georgia (including Atlanta) and much of South Carolina where
a Marginal Risk has been expanded through.

....Front Range/Central High Plains...
Moisture and forcing will remain favorable for a diurnal focus to
locally heavy rain starting on the Front Range Sunday afternoon and
spreading west in the mean flow across the central High Plains. A
Marginal Risk remains in effect for northeastern Colorado, the
Nebraska Panhandle, far southeast Wyoming into southwest South
Dakota.

Jackson

Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
852 PM EDT Sat May 24 2025
Day 3
Valid 12Z Mon May 26 2025 - 12Z Tue May 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE SOUTHERN
PLAINS TO THE TENNESSEE VALLEY...

21Z Update...
While some additional heavy rains are possible in eastern Oklahoma
and across the Ozarks, the greater threat is expected to be farther
south than recent days as an upper trough axis ejects from the
Southwest over the southern Rockies and onto the southern Plains
Monday. This will push the front and deeper moisture farther south.
Adjustments with the 12Z suite of guidance today is that the moist
southwesterly flow with energy aloft will support an axis for
storms over central/North Texas (farther west than prior runs)
through the Tennessee Valley. The Slight Risk was maintained with
expansion to the west over Texas. A targeted upgrade is likely
should these trends continue, though much of North and eastern
Texas have been fairly rain free over the past week with flash
flood guidance near their normal high values.

The motion of the upper trough axis over the Plains Monday night
should allow nocturnal activity over the central Plains. An arm to
the Marginal Risk was extended up through the KC metro into
southeast Nebraska for now, with a note that details on Plains
heavy rain threat areas should come into better focus over the
coming days.

Jackson
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
253 AM EDT Sun May 25 2025


A series of waves will develop along a frontal system eminanting
from the South. These lows will slowly progress downstream to
focus locally enhanced rains, while pooled moisture fuels local
downpours near a trailing front back across the South. Downpour
chances will be protracted with advent and reinforcement from
Midwest cyclo/frontogenesis from northern stream energies that lead
into a later period amplified upper trough signature over a
cooled/unsettled East. A Day 4/Wednesday WPC Excessive Rainfall
Outlook (ERO) Marginal Risk area shows best focus may linger over
the eastern Mid-Atlantic with lead low passage. The Day 4/5 EROs
also offer a Marginal Risk area back over the south-central
Plains/Rockies and Lower Mississippi Valley given induced return
flow and instability/upper support, with the active pattern likely
to linger later week to monitor, especially over the moist South.

In the West, a building upper ridge will lead to an expanding area
of heat from the Intermountain West into the West Coast states
this week, with temperatures rising upwards to 10 to 15+ degrees
above normal. This in particular may lead to a hazardous heat focus
for the California Central Valley late week/next weekend.

Schichtel

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
253 AM EDT Sun May 25 2025


A series of waves will develop along a frontal system eminanting
from the South. These lows will slowly progress downstream to
focus locally enhanced rains, while pooled moisture fuels local
downpours near a trailing front back across the South. Downpour
chances will be protracted with advent and reinforcement from
Midwest cyclo/frontogenesis from northern stream energies that lead
into a later period amplified upper trough signature over a
cooled/unsettled East. A Day 4/Wednesday WPC Excessive Rainfall
Outlook (ERO) Marginal Risk area shows best focus may linger over
the eastern Mid-Atlantic with lead low passage. The Day 4/5 EROs
also offer a Marginal Risk area back over the south-central
Plains/Rockies and Lower Mississippi Valley given induced return
flow and instability/upper support, with the active pattern likely
to linger later week to monitor, especially over the moist South.

In the West, a building upper ridge will lead to an expanding area
of heat from the Intermountain West into the West Coast states
this week, with temperatures rising upwards to 10 to 15+ degrees
above normal. This in particular may lead to a hazardous heat focus
for the California Central Valley late week/next weekend.

Schichtel

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
214 PM EDT Wed May 7 2025

Valid 00Z Thu May 08 2025 - 00Z Sun May 11 2025


...Colorado...
Day 1...

Lingering vorticity on the western side of the departing upper low
will still trigger some light snow over the San Juans this evening
before tapering off tonight/early Thursday. WPC probabilities for
at least an additional 4 inches of snow after 00Z are low (10-40%)
above 11,000ft.

For days 2-3, the probability of at least 4 inches of snow is less
than 10%.

The probability of significant freezing rain across the CONUS is
less than 10%.

Note - this is the last regularly scheduled discussion (QPFHSD)
for the 2024-2025 winter season. Unless a significant winter
weather threat emerges, this discussion will next be updated on or
about September 25, 2025.


Fracasso

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
253 AM EDT Sun May 25 2025

Valid 12Z Wed May 28 2025 - 12Z Sun Jun 01 2025


...Overview...

This medium range period begins midweek with a slow to progress
upper level pattern lingering over the lower 48, with split flow to
include a couple of embedded cutoff lows. A northern stream low
will meander over the north-central U.S. and Midwest this week
while an offshore southern stream low will only gradually approach
the Southwest U.S. as upper ridging builds heat over the West. The
northern stream low should gain momentum heading into next weekend
as it tends to sync into amplified upper level troughing. This
pattern will result in a period with areas of wet unsettled weather
to focus from the south-central U.S. to the East/Southeast U.S.
this
week. Meanwhile, a series of Pacific frontal approaches sluggishly
toward the Pacific Northwest may offer some modest coastal rains
chances into later week.

...Guidance/Predictability Assessment...

Guidance still offers a reasonably similar larger scale pattern
evolution for this upcoming week in overall slow to transition
flow. However, complex system interactions have led to an increase
in smaller scale flow variances through medium range time scales,
especially eminating from north-central U.S. closed low evolution.
Accordingly, favor a better compatible 18 UTC GEFS mean and 12 UTC
ECMWF/Canadian ensemble means blend along with best clustered model
guidance from the 12 UTC ECMWF and to a lesser extent the 12 UTC
Canadian to add reasonable detail. The composite seems to mitigate
smaller scale issues consistent with individual predictability.
WPC product continuity is well maintained, with a solution in line
with favorable 00 UTC guidance trends of the ECMWF/Canadian/UKMET.

...Weather/Hazards Highlights...

A series of waves will develop along a frontal system eminanting
from the South. These lows will slowly progress downstream to
focus locally enhanced rains, while pooled moisture fuels local
downpours near a trailing front back across the South. Downpour
chances will be protracted with advent and reinforcement from
Midwest cyclo/frontogenesis from northern stream energies that lead
into a later period amplified upper trough signature over a
cooled/unsettled East. A Day 4/Wednesday WPC Excessive Rainfall
Outlook (ERO) Marginal Risk area shows best focus may linger over
the eastern Mid-Atlantic with lead low passage. The Day 4/5 EROs
also offer a Marginal Risk area back over the south-central
Plains/Rockies and Lower Mississippi Valley given induced return
flow and instability/upper support, with the active pattern likely
to linger later week to monitor, especially over the moist South.

In the West, a building upper ridge will lead to an expanding area
of heat from the Intermountain West into the West Coast states
this week, with temperatures rising upwards to 10 to 15+ degrees
above normal. This in particular may lead to a hazardous heat focus
for the California Central Valley late week/next weekend.

Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw