Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
317 AM EDT Tue Apr 22 2025

Valid 12Z Tue Apr 22 2025 - 12Z Thu Apr 24 2025

...There is a Marginal Risk of excessive rainfall over parts of the
Southern Plains on Tuesday and Central/Southern Plains on Wednesday...

...There is a Slight Risk of severe thunderstorms over parts of the
Central/Southern Plains on Tuesday and the Southern Plains on Wednesday...

On Tuesday, a front extending from the Northern Plains/Upper Mississippi
Valley to the Central Plains/Central Rockies will move eastward to the
Upper/Middle Mississippi Valley and the Central Plains/Central Rockies by
Tuesday evening and dissipate overnight Tuesday. Also, on Tuesday, a
second front moving southward out of Central Canada will move eastward to
the Upper Great Lakes to the Middle Mississippi Valley and then westward
into the Central Plains by Thursday morning.

On Tuesday, moisture streams northward over the Central/Southern Plains,
intersecting the boundary over the Central Plains as a dryline develops
over the Southern High Plains. Showers and severe thunderstorms will
develop over the Southern High Plains/Central Plains along and ahead of
the front and east of the dryline. Therefore, the SPC has issued a Slight
Risk (level 2/5) of severe thunderstorms over parts of the Southern High
Plains/Central Plains through Wednesday morning. The hazards associated
with these thunderstorms are frequent lightning, severe thunderstorm wind
gusts, hail, and a few tornadoes. In addition, showers and thunderstorms
will develop over parts of the Upper/Middle Mississippi Valley and Great
Lakes.

Furthermore, the showers and thunderstorms will produce moderate to heavy
rain over parts of the Southern High Plains. Therefore, the WPC has issued
a Marginal Risk (level 1/4) of excessive rainfall over parts of the
Southern High Plains through Wednesday morning. The associated heavy rain
will create localized areas of flash flooding, affecting areas that
experience rapid runoff with heavy rain.

A third front extending from the Northeast to the Mid-Atlantic and then
southwestward to the Lower Mississippi Valley and Southern Plains will
move eastward off the Northeast/northern Mid-Atlantic Coast by overnight
Tuesday. The western end of the boundary will linger across the Southeast
through Thursday morning.

On Tuesday, showers and thunderstorms will develop along the boundary from
the southern Mid-Atlantic to the Lower Mississippi Valley/Central Gulf
Coast. In addition, strong to severe thunderstorms will develop over parts
of the southern Mid-Atlantic and a second area over the Central Gulf
Coast. Therefore, the SPC has issued a Marginal Risk (level 1/5) of severe
thunderstorms over parts of the southern Mid-Atlantic and Central Gulf
Coast through Wednesday morning. The hazards associated with these
thunderstorms are frequent lightning, severe thunderstorm wind gusts,
hail, and a minimal threat of tornadoes.

On Wednesday, showers and thunderstorms will develop along the boundary
over parts of the Upper/Middle Mississippi Valley to the Central Plains
westward into parts of the Great Basin. Moisture will continue to stream
northward over the Plains as showers and severe thunderstorms will develop
east of the dryline over the Southern High Plains. Therefore, the SPC has
issued a Slight Risk (level 2/5) of severe thunderstorms over parts of the
Southern High Plains from Wednesday into Thursday morning. The hazards
associated with these thunderstorms are frequent lightning, severe
thunderstorm wind gusts, hail, and a few tornadoes.

Moreover, showers and thunderstorms will produce moderate to heavy rain
over parts of the Central/Southern Plains. Therefore, the WPC has issued a
Marginal Risk (level 1/4) of excessive rainfall over parts of the
Central/Southern Plains from Wednesday into Thursday morning. The
associated heavy rain will create localized areas of flash flooding,
affecting areas that experience rapid runoff with heavy rain.

Furthermore, showers and thunderstorms will develop on Wednesday along and
near the old boundary extending from the southern Mid-Atlantic to the
Central Gulf Coast/Southern Plains.

Meanwhile, upper-level energy over the Northern Rockies will trigger rain
and highest-elevation snow over parts of the area on Tuesday and Wednesday.


Ziegenfelder


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
200 AM EDT Tue Apr 22 2025

Valid 12Z Fri Apr 25 2025 - 12Z Tue Apr 29 2025


...Overview...

Widespread rains/thunderstorms with locally heavy downpours will
steadily spread into the east-central and east/northeastern U.S.
with a low pressure/frontal system translation into late week.
Meanwhile, ample upper troughing will move from the eastern Pacific
into the West and promote modest precipitation, with a main focus
over the Northwest. Snow is likely for elevations into the north-
central Rockies, as also enhanced by Plains cyclogenesis and
frontogenesis, and associated deep moist inflow ahead of the upper
trough and developing storm will significantly increase rain and
thunderstorm chances and spacial coverage across the central U.S.
once again over the weekend and into early next week to monitor.

...Guidance/Predictability Assessment...

Model and ensemble forecast spread has decreased in the latest
runs overall in line with machine learning guidance, bolstering
forecast confidence. However, recent cycle-cycle run consistency
issues do temper expectations in a early warm season pattern with
much lingering uncertainties with local convection. That said,
there is now a more defined signal favoring flow amplitude with
more orgainzed system genesis over time to build predictability.

Accordingly, the WPC medium range product suite was primarily
derived from a broad composite blend of best clustered guidance
from the 18 UTC GFS/GEFS mean, the 12 UTC ECMWF/Canadian and
ECMWF/Canadian ensemble means along with a compatible 01 UTC
National Blend of Models. This plan maintains good continuity,
generally in line with latest available 00 UTC guidance trends.

...Weather/Hazards Highlights...

A number of slowly progressive upper features and surface based
systems will continue to work over mainly the eastern half of the
nation into late week to focus local weather/convection. Recent and
ongoing rainfall over some portions of this broad region will make
some areas susceptible to additional rains. By Friday, a low
pressure system and its trailing front is likely to move across the
Mississippi Valley toward the Great Lakes, spreading thunderstorm
chances into those areas. A Day 4/Friday WPC Excessive Rainfall
Outlook Marginal Risk area remains from Arkansas through portions
of the Tennessee and Ohio Valleys for localized flooding with heavy
rain, with minor adjustments from continuity. Some guidance
suggests heavy rainfall farther northeast into the Upper Ohio
Valley into the Lower Great Lakes region to monitor for emergence
Friday into the weekend farther downsteam over the East. A WPC Day
5/Saturday ERO Marginal Risk area was introduced from the
northeastern Mid-Atlantic through southern New England given
favorable ingredients.

Meanwhile, despite some model guidance uncertainties in the
details, upper trough amplification and digging in the eastern
Pacific late this week moving into the West this weekend, along
with surface system genesis and slow but steady system translation
still offers increased light to moderate widespread rain chances
and mountain snows. Renewed moisture streaming in east of the
trough plus lingering boundaries in the area will allow for
additional rounds of possibly heavy rain and thunderstorms in the
Plains and Mississippi Valley by the weekend. Initial thought is
to offer a southern High Plains WPC Marginal Risk ERO for Day 5
(12 UTC Saturday to 12 UTC Sunday) given upper difluence with upper
trough approach and bisecting front/dryline instabilities.
Organized activity should then increasingly transform into an
emerging comma-shaped rainfall area broadly sweeping over the
central U.S. into early next week given expected surface low and
wavy frontal structure development and evolution. This will likely
include some enhanced main low winds and strong to severe weather.

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
202 AM EDT Tue Apr 22 2025

Valid 00Z Wed 23 Apr 2025 - 00Z Wed 30 Apr 2025


...Protracted wet pattern...

It generally remains the case that island trades have increased
as surface high pressure cells bridge to the north of the state.
This favors a generally wet trade pattern given lingering moisture
for early this week, with more focus on windward terrain. A flood
watch is now in place for the western islands. Guidance generally
agrees that upper trough/closed low and surface system genesis
remains set to dig and settle just to the west of the state by
mid-later week. Weakening and veering lead flow to southeasterly
to southerly winds over the state should deepen lead moisture to
fuel showers and some heavier local downpours. The upper system
should slowly eject and lose influence into the weekend, but a
moisture pooling trailing front and deep showers focus may work
slowly into the state from the west, with an associated weather
focus possibly lingering into early next week.

Schichtel

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1100 AM EDT Tue Apr 22 2025
Day 1
Valid 16Z Tue Apr 22 2025 - 12Z Wed Apr 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTH...

The inherited Marginal Risk areas across the Panhandles of Texas
and Oklahoma as well as the newly expanded Marginal from the lower
Mississippi Valley to the southern Appalachians were combined to
cover much of Texas with this update. There remain 2 distinct
features forcing the thunderstorms, a stationary boundary draped
from the Lower Mississippi Valley to the southern Appalachians, and
a progressive dry line that will spawn new thunderstorms across
western and central Texas later this afternoon though tonight.
While the area in between...namely east Texas, has a notably lower
chance of flash flooding, enough of the guidance suggests there to
be enough overlap late tonight between earlier convection and those
areas harder hit over the past day or so to justify the combining
of the inherited Marginal Risk areas.

This summer-like pattern of convection is much less predictable
than the colder season larger precipitation shields of the past
several months. It's therefore becoming the season where larger
swaths of the country are broadly under a localized threat for
flash flooding as thunderstorm complexes interact with one another
in largely unpredictable ways, with enhanced impacts should those
interactions occur over urban areas. The combined Marginals thus
highlight these larger features for the potential for training
convection once cell interactions are taken into account. Given the
increasing amounts of atmospheric Gulf moisture advecting into
these features, resultant convection will have the potential to
cause localized rainfall rates of up to 2 inches per hour.
Localized flash flooding is most likely to occur where these rates
coincide with lower FFGs from recent heavy rainfall.

Wegman


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1100 AM EDT Tue Apr 22 2025
Day 2
Valid 12Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS...

Several shortwaves will be exiting the Rockies throughout the day
with several pockets of convective development sprawled across the
Central and Southern High Plains by the evening hours. While the
confidence continues to be lower on the maximum amounts there is
however higher confidence on the potential for scattered flash
flood prospects. Although the location of QPF maxima vary, there
is a general consensus of a widespread 1 to 2 inches from the Front
Range of Colorado/Wyoming/Nebraska south to the Red River Basin
near Texas to Kansas/Oklahoma. Some of these areas will have seen
significant rainfall prior to any additional impacts leading to
some localized lower FFG indices once the event occurs. The
inherited Marginal continued to mostly highlight areas across the
Plains that had an elevated threat for heavy rainfall and flash
flooding. The latest guidance and WPC QPF trended higher with QPF
over northeast Kansas, southern Nebraska, southwest Iowa and
northwest Missouri. As such, the Marginal Risk area was modified to
encompass that part of the region.

Campbell/Kleebauer


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1100 AM EDT Tue Apr 22 2025
Day 3
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...

The pattern will be favorable for multiple rounds of showers and
thunderstorms to move through the south-central U.S. With a moist,
unstable flow expected and shortwave energy passing through heavy
rainfall will likely develop across the region which may lead to
local flash flooding. Areal averages of 1 to 2 inches are forecast
with locally higher amounts possible. A Slight Risk for excessive
rainfall is in effect for a large portion of Kansas, northern
Oklahoma, far northwest Arkansas and western Missouri. A Marginal
Risk area spans from northern Texas to southern Nebraska and
extreme southwest Iowa.

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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
200 AM EDT Tue Apr 22 2025


A number of slowly progressive upper features and surface based
systems will continue to work over mainly the eastern half of the
nation into late week to focus local weather/convection. Recent and
ongoing rainfall over some portions of this broad region will make
some areas susceptible to additional rains. By Friday, a low
pressure system and its trailing front is likely to move across the
Mississippi Valley toward the Great Lakes, spreading thunderstorm
chances into those areas. A Day 4/Friday WPC Excessive Rainfall
Outlook Marginal Risk area remains from Arkansas through portions
of the Tennessee and Ohio Valleys for localized flooding with heavy
rain, with minor adjustments from continuity. Some guidance
suggests heavy rainfall farther northeast into the Upper Ohio
Valley into the Lower Great Lakes region to monitor for emergence
Friday into the weekend farther downsteam over the East. A WPC Day
5/Saturday ERO Marginal Risk area was introduced from the
northeastern Mid-Atlantic through southern New England given
favorable ingredients.

Meanwhile, despite some model guidance uncertainties in the
details, upper trough amplification and digging in the eastern
Pacific late this week moving into the West this weekend, along
with surface system genesis and slow but steady system translation
still offers increased light to moderate widespread rain chances
and mountain snows. Renewed moisture streaming in east of the
trough plus lingering boundaries in the area will allow for
additional rounds of possibly heavy rain and thunderstorms in the
Plains and Mississippi Valley by the weekend. Initial thought is
to offer a southern High Plains WPC Marginal Risk ERO for Day 5
(12 UTC Saturday to 12 UTC Sunday) given upper difluence with upper
trough approach and bisecting front/dryline instabilities.
Organized activity should then increasingly transform into an
emerging comma-shaped rainfall area broadly sweeping over the
central U.S. into early next week given expected surface low and
wavy frontal structure development and evolution. This will likely
include some enhanced main low winds and strong to severe weather.

Schichtel

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
200 AM EDT Tue Apr 22 2025


A number of slowly progressive upper features and surface based
systems will continue to work over mainly the eastern half of the
nation into late week to focus local weather/convection. Recent and
ongoing rainfall over some portions of this broad region will make
some areas susceptible to additional rains. By Friday, a low
pressure system and its trailing front is likely to move across the
Mississippi Valley toward the Great Lakes, spreading thunderstorm
chances into those areas. A Day 4/Friday WPC Excessive Rainfall
Outlook Marginal Risk area remains from Arkansas through portions
of the Tennessee and Ohio Valleys for localized flooding with heavy
rain, with minor adjustments from continuity. Some guidance
suggests heavy rainfall farther northeast into the Upper Ohio
Valley into the Lower Great Lakes region to monitor for emergence
Friday into the weekend farther downsteam over the East. A WPC Day
5/Saturday ERO Marginal Risk area was introduced from the
northeastern Mid-Atlantic through southern New England given
favorable ingredients.

Meanwhile, despite some model guidance uncertainties in the
details, upper trough amplification and digging in the eastern
Pacific late this week moving into the West this weekend, along
with surface system genesis and slow but steady system translation
still offers increased light to moderate widespread rain chances
and mountain snows. Renewed moisture streaming in east of the
trough plus lingering boundaries in the area will allow for
additional rounds of possibly heavy rain and thunderstorms in the
Plains and Mississippi Valley by the weekend. Initial thought is
to offer a southern High Plains WPC Marginal Risk ERO for Day 5
(12 UTC Saturday to 12 UTC Sunday) given upper difluence with upper
trough approach and bisecting front/dryline instabilities.
Organized activity should then increasingly transform into an
emerging comma-shaped rainfall area broadly sweeping over the
central U.S. into early next week given expected surface low and
wavy frontal structure development and evolution. This will likely
include some enhanced main low winds and strong to severe weather.

Schichtel

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
253 AM EDT Tue Apr 22 2025

Valid 12Z Tue Apr 22 2025 - 12Z Fri Apr 25 2025


...Northern Rockies...
Days 2-3...

A drier stretch is expected to prevail today outside of a few high
elevation snow showers near Yellowstone before the next shortwave
slides over the northern Rockies Wednesday night into Thursday.
This feature will spread snow across southwestern MT and
northwestern WY ahead of a much deeper upper trough approaching the
West Coast by the end of D3. Broad west-southwesterly flow will
aid in overspreading Pacific moisture into the region, while also
rising snow levels to around 6,000-8,000 ft during this time frame.
Amounts will be generally light, focused on the Absarokas, Wind
River, and Bighorns, where WPC probabilities for at least 8 inches
of snow through 12Z Friday are low (20-40%) at the highest
elevations.

The probability of at least 0.10" of freezing rain across CONUS is
less than 10%.


Snell

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
200 AM EDT Tue Apr 22 2025

Valid 12Z Fri Apr 25 2025 - 12Z Tue Apr 29 2025


...Overview...

Widespread rains/thunderstorms with locally heavy downpours will
steadily spread into the east-central and east/northeastern U.S.
with a low pressure/frontal system translation into late week.
Meanwhile, ample upper troughing will move from the eastern Pacific
into the West and promote modest precipitation, with a main focus
over the Northwest. Snow is likely for elevations into the north-
central Rockies, as also enhanced by Plains cyclogenesis and
frontogenesis, and associated deep moist inflow ahead of the upper
trough and developing storm will significantly increase rain and
thunderstorm chances and spacial coverage across the central U.S.
once again over the weekend and into early next week to monitor.

...Guidance/Predictability Assessment...

Model and ensemble forecast spread has decreased in the latest
runs overall in line with machine learning guidance, bolstering
forecast confidence. However, recent cycle-cycle run consistency
issues do temper expectations in a early warm season pattern with
much lingering uncertainties with local convection. That said,
there is now a more defined signal favoring flow amplitude with
more orgainzed system genesis over time to build predictability.

Accordingly, the WPC medium range product suite was primarily
derived from a broad composite blend of best clustered guidance
from the 18 UTC GFS/GEFS mean, the 12 UTC ECMWF/Canadian and
ECMWF/Canadian ensemble means along with a compatible 01 UTC
National Blend of Models. This plan maintains good continuity,
generally in line with latest available 00 UTC guidance trends.

...Weather/Hazards Highlights...

A number of slowly progressive upper features and surface based
systems will continue to work over mainly the eastern half of the
nation into late week to focus local weather/convection. Recent and
ongoing rainfall over some portions of this broad region will make
some areas susceptible to additional rains. By Friday, a low
pressure system and its trailing front is likely to move across the
Mississippi Valley toward the Great Lakes, spreading thunderstorm
chances into those areas. A Day 4/Friday WPC Excessive Rainfall
Outlook Marginal Risk area remains from Arkansas through portions
of the Tennessee and Ohio Valleys for localized flooding with heavy
rain, with minor adjustments from continuity. Some guidance
suggests heavy rainfall farther northeast into the Upper Ohio
Valley into the Lower Great Lakes region to monitor for emergence
Friday into the weekend farther downsteam over the East. A WPC Day
5/Saturday ERO Marginal Risk area was introduced from the
northeastern Mid-Atlantic through southern New England given
favorable ingredients.

Meanwhile, despite some model guidance uncertainties in the
details, upper trough amplification and digging in the eastern
Pacific late this week moving into the West this weekend, along
with surface system genesis and slow but steady system translation
still offers increased light to moderate widespread rain chances
and mountain snows. Renewed moisture streaming in east of the
trough plus lingering boundaries in the area will allow for
additional rounds of possibly heavy rain and thunderstorms in the
Plains and Mississippi Valley by the weekend. Initial thought is
to offer a southern High Plains WPC Marginal Risk ERO for Day 5
(12 UTC Saturday to 12 UTC Sunday) given upper difluence with upper
trough approach and bisecting front/dryline instabilities.
Organized activity should then increasingly transform into an
emerging comma-shaped rainfall area broadly sweeping over the
central U.S. into early next week given expected surface low and
wavy frontal structure development and evolution. This will likely
include some enhanced main low winds and strong to severe weather.

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