Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
311 PM EDT Sat May 31 2025

Valid 00Z Sun Jun 01 2025 - 00Z Tue Jun 03 2025

...Moderate to heavy rainfall and localized flash flooding continues into
this evening for interior New England...

...Showers and thunderstorms expected to reach the Desert Southwest Sunday
night and then the Four Corners Monday morning with a risk for flash
flooding...

...A round of rain expected for the northern Rockies/High Plains Sunday
night into Monday morning with gusty winds...

...Storm chances shift from the southern Plains Sunday to the
central/northern Plains Monday...

An anomalously deep low pressure system for late May continues to churn
northward through New England this afternoon (Saturday) accompanied by
widespread showers and thunderstorms. Plentiful moisture leading to
locally heavy downpours (rain rates of 1"/hr) and repeated rounds of
storms focused through portions of Vermont and New Hampshire may lead to
some scattered instances of flash flooding, with a Slight Risk of
Excessive Rainfall (level 2/4) in effect. Storms will lift northeastward
from central New England into Maine through this evening and should come
to an end for all locations by Sunday morning. Forecast high temperatures
Sunday more broadly across the Northeast and into the Mid-Atlantic, Lower
Great Lakes, and Ohio Valley will remain below average Sunday under an
associated upper-low and following a cold front passage, ranging from the
50s and 60s in the Interior Northeast and 60s and 70s elsewhere. Highs
will climb closer to average and be in the 70s for most by Monday as the
upper-low departs the region.

The upper-ridge bringing very hot, Summer-like and record heat to the West
Saturday will begin to shift eastward on Sunday, with well above average
temperatures into the 80s and 90s stretching from the Interior West into
the northern Plains. The heat will shift into the Upper Midwest on Monday
while an upper trough/accompanying surface cold front moving south through
the interior West brings much cooler temperatures to the northern
Rockies/High plains (highs in the 60s) and more seasonable temperatures
elsewhere in the Great Basin and along the West Coast (70s and 80s).
Showers and thunderstorms, along with some gusty winds, will accompany the
cold front passing through the northern Rockies/High Plains Sunday night
into Monday. Meanwhile, further south, moisture associated with the
remnants of Alvin will flow northward into the Southwest Sunday bringing
showers and thunderstorms capable of locally heavy rainfall. Some
scattered instances of flash flooding will be possible, especially across
southeastern Arizona where a Slight Risk of Excessive Rainfall is in
place. The storms will shift northward into the Four Corners region Monday
with moderate to locally heavy rainfall and additional isolated instances
of flash flooding possible. Below average highs are expected, with 80s to
low 90s in the Desert Southwest Sunday and 60s across the Four Corners
region by Monday.

An upper-level shortwave and accompanying surface cold front moving
southward over the central/southern Plains will trigger a round of storms
this evening. Some storms may be severe across portions of southern Kansas
and central Oklahoma, with a Slight Risk from the Storm Prediction Center
(level 2/5) for the threat of large hail and damaging winds. The front
will continue southward into central/eastern Texas Sunday, with another
Slight Risk of severe weather in effect for the threat of very large hail
and some damaging winds. Then, on Monday, anomalously high moisture will
return northward ahead of the approaching upper-trough/cold front passing
through the northern Rockies and into the central/northern Plains and
Upper Midwest. Thunderstorm development is expected to focus along the
cold front, with Slight Risks in effect for both severe weather and
Excessive Rainfall/flash flooding, generally from eastern South Dakota
southwest through central/western Nebraska and into southeastern
Wyoming/northeastern Colorado. Forecast highs across the central/southern
Plains and into the Mississippi Valley will be around to above average the
next couple of days, with 80s and 90s forecast.

Elsewhere, daily shower and thunderstorm chances continue for Florida. An
upper-level shortwave passing over the Southeast will lead to some
scattered storm chances Sunday. Forecast highs Sunday and Monday are
generally around average, with mostly 80s expected.

Putnam


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
252 PM EDT Sat May 31 2025

Valid 12Z Tue Jun 03 2025 - 12Z Sat Jun 07 2025


...Overview...
Persistent riding in the northeastern Pacific and increasing
ridging in the western Atlantic will favor a broad positively
tilted trough in between that stretches from central Canada through
the Southwest to the far eastern Pacific subtropics. The broad
trough supports progressive systems moving through the flow. The
wettest areas should be in the Midwest and Plains.


...Guidance/Predictability Assessment...
The latest suite of model guidance depict reasonable clustering
for most of the country that allowed for a consensus approach. For
fronts, pressures, to some degree QPF/PoPs, and winds, this
forecast was based on a multi- model blend of the 00Z
CMC/UKMET/ECWMF
and 06Z GFS initially before adding the EC and GEFS ensemble means
into the mix. Other fields were derived primarily from the 13z NBM.


...Weather/Hazards Highlights...
The beginning of the week starts with a frontal system moving
through the Northern and Central Plains toward the Mid-Mississippi
Valley. This front will be the focus for scattered to widespread
showers and thunderstorms, with some produce heavy rainfall. WPC
added Slight Risk areas for excessive rainfall/flash flooding
across for days 4-5/Tuesday and Wednesday for portions of
Oklahoma and northern Texas where roughly 3-7" of areal averaged
rain is explicitly forecast, and in and near the Iowa/Illinois/
Missouri border junction for day 4/Tuesday in a region where local
amounts in the 3-5" range are possible. For areas near the
Iowa/Illinois border, the flash flood threat would be primarily in
urban areas. The front advances east/southward along with the heavy
rain threat (into the Southern Plains/Lower Mississippi
Valley/Mid- South) by the end of next week. Drier conditions are
expected along both the East and West Coasts with the exception of
Florida which may see more appreciable rainfall over the southern
portions in the vicinity of a dying oceanic boundary, where a
Marginal Risk area for excessive rainfall/flash flooding was added
for day 4/Tuesday. Some mountain areas of Wyoming may see a few
inches of snow as colder air comes in behind the front.

Near normal to above normal temperatures are expected to spread
across the central and eastern states. With daily temperatures in
the 80s/90s a Moderate HeatRisk threat is expected to develop for
some regions-- take precautions in the heat such as increased water
intake and more time in air conditioned areas to avoid heat
exhaustion and heat stroke. Parts of South Texas will see more
days of highs into the upper 90s and low 100s with low
probabilities (20-40%) of reaching heat index values of at least
110F. Much cooler temperatures will follow behind the cold front,
starting in the Rockies on Monday then into the Plains thereafter,
but moderating with time. Much of the West will see near to
slightly above normal temperatures, especially later in the week.


Roth


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
424 AM EDT Sat May 31 2025

Valid 00Z Sun 01 Jun 2025 - 00Z Sun 08 Jun 2025

Easterly winds of 10-15 knots can be expected with building high
pressure positioned northeast of the islands. Meanwhile an upper
trough and surface front will be slowly advancing from the west.
Very light accumulations of rain possible as this feature
approaches from the west.

Campbell

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Sat May 31 2025
Day 1
Valid 16Z Sat May 31 2025 - 12Z Sun Jun 01 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
NEW ENGLAND...

...New England...
Impressive almost-June low pressure system will continue to track
northeast across Maine and get pulled NW into Canada as the parent
shortwave gets absorbed into a large closed low across Quebec. The
model trends have continued to pivot just a bit farther west with
the impressive deformation that will continue to support heavy rain
rates, especially across Vermont, through this evening. Although
instability will remain modest, generally less than 500 J/kg,
impressive PWs around 1" (near the 75th percentile) will support
rainfall rates within the strong ascent that could reach 1"/hr at
times (although will generally be around 0.5"/hr). Still, this rain
will be persistent, and Corfidi vectors becoming anti-parallel to
the mean flow suggest training to support total rainfall for which
the GEFS/ECENS/HREF probabilities all suggest will exceed 3 inches across
the sensitive terrain/soils of Vermont, supporting the continued
SLGT risk.

Farther east, the high-res CAMs have become a bit more aggressive
with rainfall rates around 1"/hr lifting north across eastern Maine
within higher PWs (above the 90th percentile) and greater
instability. While training here is less of a concern, clusters of
convection organized through 30-40 kts of bulk shear could still
produce local flash flood concerns, so the MRGL risk was pulled all
the way into Downeast Maine.


...Southern Plains...
Broad NW flow on the upwind side of an expansive trough centered
over Ontario will persist over the Plains as an embedded but
potent shortwave tracks SE tonight. This shortwave will push a
wave of low pressure and weakening cold front south into Oklahoma
tonight, where it will interact with a slowly advancing warm front
out of Texas on the intensifying LLJ. This LLJ, progged to reach at
least a modest 20-25 kts from the SW, will transport more robust
thermodynamics (PWs to 1.5 inches and MUCAPE above 1000 J/kg), to
support expanding convection along this decaying cold front. With
bulk shear expected to be in the 30-40 kt range, convection will
likely grow upscale into clusters or an MCS tonight as it races
southeast on 20-25 kts of 0-6km mean winds. This this will limit
the duration of heavy rain, rates that will likely reach 1-2"/hr
could result in isolated instances of flash flooding, especially
during any short-term training that may develop on the periphery of
this MCS. The guidance, as expected, features considerable
longitudinal spread of the MCS path, which makes the cosmetic
adjustments to the inherited MRGL risk the best approach for the
risk area tonight.


Weiss

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Sat May 31 2025
Day 2
Valid 12Z Sun Jun 01 2025 - 12Z Mon Jun 02 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHWEST...

Maintained the Marginal Risk area over parts of the Southwest US on
Sunday as a persistent closed upper level low off of the Baja
Peninsula interacts with a plume of deep moisture that has its
origins in the subtropics. As the upper low begins to fill and
slowly eject northeast on Sunday...subtle height falls in the mid-
levels will reinforce the northward transport into the area as
reflected by NAEFS PWs above 1.25 inches, or above the 99th
percentile surging into AZ/CA/NV late Sunday night/early Monday
morning. This will overlap of at least modest instability,
potentially as high as 250-500 J/kg, to support increasing
convective coverage late in the period. There remains some concern
as to whether or not the increased amount of mid-level moisture
leads to enhanced cloud cover and what impact that might have on
the amount of coverage/intensity of convection. There was some
uptick in the 31/00Z model guidance with an a corresponding
increase in ECENS/GEFS probabilities for even 1" of rainfall. Even
so...those probabilities seem low considering the precipitable
water anomalies in place and the amount of diffluent flow aloft to
the east of the closed low east of the Baja peninsula. The
expectation is that once showers to develop they could contain rain
rates of above 0.5"/hr, which will support at least an isolated
potential for flash flooding where storms move most slowly beneath
the upper low.

Bann

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Sat May 31 2025
Day 3
Valid 12Z Mon Jun 02 2025 - 12Z Tue Jun 03 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE CENTRAL PLAINS ON MONDAY/MONDAY NIGHT...

...Rockies to the Plains...
Moisture that had been streaming northward into the Southwest US on
Sunday will continue to be drawn northward on Monday as a northern
stream trough along the US/Canadian border amplifies and a cold
front makes its way southward. A 35 to 45 kt southerly low level
jet develops and leads to enhanced moisture flux convergence along
the front from Colorado into Nebraska and a part of South Dakota
Monday night/early Tuesday morning. With added upper support from
the entrance region of an 80 to 100 kt upper jet in the form of
increasing divergence aloft and precipitable water values in the
range of 1.5 to 1.75 inches pooling along the front...at or above
the 90th percentile for this time of year and over 2 standardized
anomalies...rainfall rates in excess an inch per hour and the
potential for repeat convection may result in instances of flash
flooding.

...South Florida...
Introduced a Marginal Risk of excessive rainfall mainly across the
urban areas of the southern Florida peninsula as an east to west
oriented front settles into the area from the north and stalls. Mid
and upper level heights should be falling in response to the
approach of a mid/upper level wave from the eastern Gulf during the
afternoon...helping set the stage for scattered late day showers
and thunderstorms capable of producing locally heavy rainfall.
Precipitable water values of 1.75 inches or greater should be in
place across the peninsula...some 1.5 to 2 standardized anomalies
along the coast or just off shore over the Florida Strait.
Localized rainfall rates of 1 to 2 inches per hour are possible.

Bann

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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
252 PM EDT Sat May 31 2025

The beginning of the week starts with a frontal system moving
through the Northern and Central Plains toward the Mid-Mississippi
Valley. This front will be the focus for scattered to widespread
showers and thunderstorms, with some produce heavy rainfall. WPC
added Slight Risk areas for excessive rainfall/flash flooding
across for days 4-5/Tuesday and Wednesday for portions of
Oklahoma and northern Texas where roughly 3-7" of areal averaged
rain is explicitly forecast, and in and near the Iowa/Illinois/
Missouri border junction for day 4/Tuesday in a region where local
amounts in the 3-5" range are possible. For areas near the
Iowa/Illinois border, the flash flood threat would be primarily in
urban areas. The front advances east/southward along with the heavy
rain threat (into the Southern Plains/Lower Mississippi
Valley/Mid- South) by the end of next week. Drier conditions are
expected along both the East and West Coasts with the exception of
Florida which may see more appreciable rainfall over the southern
portions in the vicinity of a dying oceanic boundary, where a
Marginal Risk area for excessive rainfall/flash flooding was added
for day 4/Tuesday. Some mountain areas of Wyoming may see a few
inches of snow as colder air comes in behind the front.

Near normal to above normal temperatures are expected to spread
across the central and eastern states. With daily temperatures in
the 80s/90s a Moderate HeatRisk threat is expected to develop for
some regions-- take precautions in the heat such as increased water
intake and more time in air conditioned areas to avoid heat
exhaustion and heat stroke. Parts of South Texas will see more
days of highs into the upper 90s and low 100s with low
probabilities (20-40%) of reaching heat index values of at least
110F. Much cooler temperatures will follow behind the cold front,
starting in the Rockies on Monday then into the Plains thereafter,
but moderating with time. Much of the West will see near to
slightly above normal temperatures, especially later in the week.


Roth

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
252 PM EDT Sat May 31 2025

The beginning of the week starts with a frontal system moving
through the Northern and Central Plains toward the Mid-Mississippi
Valley. This front will be the focus for scattered to widespread
showers and thunderstorms, with some produce heavy rainfall. WPC
added Slight Risk areas for excessive rainfall/flash flooding
across for days 4-5/Tuesday and Wednesday for portions of
Oklahoma and northern Texas where roughly 3-7" of areal averaged
rain is explicitly forecast, and in and near the Iowa/Illinois/
Missouri border junction for day 4/Tuesday in a region where local
amounts in the 3-5" range are possible. For areas near the
Iowa/Illinois border, the flash flood threat would be primarily in
urban areas. The front advances east/southward along with the heavy
rain threat (into the Southern Plains/Lower Mississippi
Valley/Mid- South) by the end of next week. Drier conditions are
expected along both the East and West Coasts with the exception of
Florida which may see more appreciable rainfall over the southern
portions in the vicinity of a dying oceanic boundary, where a
Marginal Risk area for excessive rainfall/flash flooding was added
for day 4/Tuesday. Some mountain areas of Wyoming may see a few
inches of snow as colder air comes in behind the front.

Near normal to above normal temperatures are expected to spread
across the central and eastern states. With daily temperatures in
the 80s/90s a Moderate HeatRisk threat is expected to develop for
some regions-- take precautions in the heat such as increased water
intake and more time in air conditioned areas to avoid heat
exhaustion and heat stroke. Parts of South Texas will see more
days of highs into the upper 90s and low 100s with low
probabilities (20-40%) of reaching heat index values of at least
110F. Much cooler temperatures will follow behind the cold front,
starting in the Rockies on Monday then into the Plains thereafter,
but moderating with time. Much of the West will see near to
slightly above normal temperatures, especially later in the week.


Roth

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
252 PM EDT Sat May 31 2025

Valid 12Z Tue Jun 03 2025 - 12Z Sat Jun 07 2025


...Overview...
Persistent riding in the northeastern Pacific and increasing
ridging in the western Atlantic will favor a broad positively
tilted trough in between that stretches from central Canada through
the Southwest to the far eastern Pacific subtropics. The broad
trough supports progressive systems moving through the flow. The
wettest areas should be in the Midwest and Plains.


...Guidance/Predictability Assessment...
The latest suite of model guidance depict reasonable clustering
for most of the country that allowed for a consensus approach. For
fronts, pressures, to some degree QPF/PoPs, and winds, this
forecast was based on a multi- model blend of the 00Z
CMC/UKMET/ECWMF
and 06Z GFS initially before adding the EC and GEFS ensemble means
into the mix. Other fields were derived primarily from the 13z NBM.


...Weather/Hazards Highlights...
The beginning of the week starts with a frontal system moving
through the Northern and Central Plains toward the Mid-Mississippi
Valley. This front will be the focus for scattered to widespread
showers and thunderstorms, with some produce heavy rainfall. WPC
added Slight Risk areas for excessive rainfall/flash flooding
across for days 4-5/Tuesday and Wednesday for portions of
Oklahoma and northern Texas where roughly 3-7" of areal averaged
rain is explicitly forecast, and in and near the Iowa/Illinois/
Missouri border junction for day 4/Tuesday in a region where local
amounts in the 3-5" range are possible. For areas near the
Iowa/Illinois border, the flash flood threat would be primarily in
urban areas. The front advances east/southward along with the heavy
rain threat (into the Southern Plains/Lower Mississippi
Valley/Mid- South) by the end of next week. Drier conditions are
expected along both the East and West Coasts with the exception of
Florida which may see more appreciable rainfall over the southern
portions in the vicinity of a dying oceanic boundary, where a
Marginal Risk area for excessive rainfall/flash flooding was added
for day 4/Tuesday. Some mountain areas of Wyoming may see a few
inches of snow as colder air comes in behind the front.

Near normal to above normal temperatures are expected to spread
across the central and eastern states. With daily temperatures in
the 80s/90s a Moderate HeatRisk threat is expected to develop for
some regions-- take precautions in the heat such as increased water
intake and more time in air conditioned areas to avoid heat
exhaustion and heat stroke. Parts of South Texas will see more
days of highs into the upper 90s and low 100s with low
probabilities (20-40%) of reaching heat index values of at least
110F. Much cooler temperatures will follow behind the cold front,
starting in the Rockies on Monday then into the Plains thereafter,
but moderating with time. Much of the West will see near to
slightly above normal temperatures, especially later in the week.


Roth


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