Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
359 PM EDT Wed Apr 29 2026

Valid 00Z Thu Apr 30 2026 - 00Z Sat May 02 2026

...Flash flood threat ramps up across portions of Texas into the
Lower Mississippi Valley Thursday into Friday...

...Heavy snow expected for higher elevations of the
central/southern Rockies Thursday and Friday...

...Cooler, below average temperatures following a frontal passage
for the central/eastern U.S. while the western U.S. trends warmer
the next few days...

Scattered to widespread showers and thunderstorms will continue
this evening into the overnight hours ahead of a cold front
stretching southward along the East Coast and then west through
the Southeast/Gulf Coast and into Texas. Greater
moisture/instability south of the front across portions of the
Southeast/Lower Mississippi Valley west through eastern and
central Texas will lead to more robust thunderstorms capable of
severe weather. The Storm Prediction Center has outlined a Slight
Risk (level 2/5) mainly for the threat of large hail and damaging
winds, and perhaps a tornado or two. Locally heavy downpours and a
few isolated instances of flash flooding are also possible. The
front will begin to clear the East Coast by Thursday morning
through the Mid-Atlantic but linger much longer for New England
where ongoing showers and thunderstorms will continue through
tonight and perhaps into Friday morning. A secondary front may
bring some scattered light showers across the Midwest and into the
Interior Northeast later Thursday with perhaps a wintry mix
possible for higher elevations of the Interior Northeast.
Meanwhile, to the south, the front will make much slower
progression, becoming quasi-stationary at times, along the Gulf
Coast west through Texas as well as into portions of the
Southwest. This boundary along with an incoming upper-wave will
support more rounds of thunderstorms over the next couple of days.
Anomalously high Gulf moisture pooling along the boundary as well
as the tendency for repeated rounds of storm development given the
quasi-stationary nature of the boundary will support a heavy
rainfall threat. Slight Risks of Excessive Rainfall (level 2/4)
have been outlooked for portions of central Texas Thursday and
central/eastern Texas east through the Lower Mississippi Valley
for Friday where the greatest threat for scattered instances of
flash flooding are expected. Higher risk categories may be
necessary as confidence grows on storm coverage/location given the
moisture in place and multi-day nature of the event.

Some scattered rain showers for lower elevations and snow for
higher elevations will continue over portions of the
northern/central Rockies through tonight as an upper-wave/frontal
boundary pass through. Then, on Thursday, as moist upslope flow
increases ahead of the incoming upper-wave over the Southwest,
more widespread, heavy precipitation is expected to develop
through the central/southern Rockies and ascendant High Plains
through Friday. Heavy snow is forecast for the regional mountain
ranges, and some snow may mix in for higher elevations along the
Front Range such as the Palmer Divide, though accumulations here
should be limited. The cold front will bring a period of below to
well below average temperatures for most of the central/eastern
U.S. through at least the end of the week. Forecast highs Thursday
and Friday generally range in the 40s and 50s from the Northern
Plains east through the Great Lakes and into the Northeast; the
50s and 60s from the central/southern Plains east through the
Middle Mississippi/Ohio Valleys to the Mid-Atlantic; and 60s and
some 70s for the Southeast. Warmer temperatures into the 80s will
be limited to south of the boundary across Florida, south Texas,
and portions of the Gulf Coast. In contrast, much of the western
U.S. will see a warm-up over the next couple of days with
temperatures settling into average to above average levels.
Forecast highs generally range in the upper 50s to mid-70s for the
Interior West; 60s and 70s along the West Coast with 80s into the
central California Valleys; and 80s and 90s for the Desert
Southwest.

Putnam


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 PM EDT Wed Apr 29 2026

Valid 12Z Sat May 02 2026 - 12Z Wed May 06 2026


...Overview...

Several disturbances rotating around a persistent upper level
closed low centered over Ontario and Quebec will help to reinforce
broadly deep troughing across the eastern U.S. this weekend into
next week. This pattern typical of springtime will likely keep
conditions cool and unsettled across parts of the Northeast, Mid-
Atlantic, Great Lakes, and Upper Midwest. Meanwhile, a weekend
frontal system with plenty of moisture will threaten portions of
the Southeast and Florida with heavy rain and isolated flooding
concerns. Then another Pacific low tries to push inland late in the
weekend into early next week, possibly bringing some low elevation
rain and mountain snow showers to parts of the West.


...Guidance/Predictability Assessment...

A fairly stable mid/upper level pattern is expected to persist
through the medium range period, featuring a large upper low and
broad troughing across the eastern U.S., and a developing Rex block
across the western U.S. The latest guidance continues to have a
good handle on the overall pattern evolution through the period,
but still with plenty of uncertainty in the details. The main
sources of uncertainty deal with several smaller scale waves/energy
rotating around the large parent upper low spinning over southeast
Canada, as well as how quickly the cut-off Pacific low portion of
the Rex block pushes inland over the Southwest. An equal model
compromise between the GFS, ECMWF, CMC, UKMET, and EC-AIFS sufficed
for the first half of the forecast period, shifting towards more
weighting on the ensemble means for the latter half. This approach
remains in line with previous WPC forecast as well as the 13z NBM,
which served as a good starting point for the WPC Day 4-7 sensible
weather grids.


...Weather/Hazards Highlights...

An occluding low pressure system pivoting across southeast Canada
will continue to foster cool, breezy, and showery conditions over
parts of the Northeast through the weekend. Some light snow may
fall across the higher elevations of northern New England and the
interior Northeast as colder air wraps in on the backside of the
low, but any accumulations are expected to be minimal. Additional
disturbances rotating around the primary low over southeast Canada
may push a few cold fronts and chances for showers into the Upper
Midwest, Great Lakes, and Northeast later this weekend into next
week, keeping temperatures near to below seasonal norms. Chilly
nighttime lows may also lead to frost and freeze concerns over
parts of the Ohio Valley, Mid-Atlantic, and central Appalachians
this weekend as well.

The developing frontal system that is expected to bring heavy rain
and potential flooding concerns from Texas to the Lower
Mississippi Valley and Deep South Thursday and Friday will shift
eastward into the Southeast on Saturday. As the frontal wave fueled
by still impressive moisture and forcing tracks towards the Mid-
Atlantic coast, a trailing cold front will trigger clusters of
thunderstorms capable of producing heavy rainfall from the
Southeast into Florida. With much of the region in severe drought,
and after coordination with the WFOs, restricted the Day 4/Sunday
ERO to just far southeast Georgia and northern Florida where the
better moisture anomalies and instability will be present. This
trims out much of the remainder of the Southeast where rainfall
should be more beneficial. On Sunday, the cold front that follows
in the wake of the strengthening coastal low moving out to sea may
stall across Florida. Should this occur, the stalled frontal zone
would then become a focus for additional heavy rain given plentiful
moisture pooling along the boundary. Thus, a Day 5/Sunday Marginal
Risk ERO continues for much of central Florida.

A slow-moving Pacific low spinning off the coast of California
late this weekend should push across California and the Great Basin
during the first half of next week. There remains some uncertainty
with how quickly the low will advance inland, but moisture will
likely be drawn in to support scattered low elevation rain and
mountain snow showers across the West, along with cooler
temperatures following several days of unseasonable warmth.


Santorelli/Miller


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, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages are at:

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
825 PM EDT Wed Apr 29 2026
Day 1
Valid 01Z Thu Apr 30 2026 - 12Z Thu Apr 30 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM CENTRAL AND
SOUTHEAST TEXAS TO THE CENTRAL GULF COAST...

01Z update...Minimal changes made to the existing Marginal Risk
area, based on the latest observational and guidance trends. HRRR
trends this evening, along with the most recent HREF and RRFS 1/3
hour QPF exceedance probabilities, would indicate relatively lower
probabilities across Central TX/Hill Country overnight; however,
guidance continues to within this W-E corridor in terms of the
development of discrete/splitting supercells. Continued active
subtropical jet and associated mid-upper level moisture anomaly
(LPW plume) will continue to enhance short-term rain rate
potential. However, the larger threat, while isolated/localized,
will be from the prolific rainfall rates underneath these
supercells, despite their fast progression. The Marginal ERO risk
aligns with the majority of SPC's Slight Risk area.

Hurley

Previous discussion below..

The Marginal Risk area was maintained with very few changes. A
threat of isolated flash flooding from heavy rainfall is still
expected, largely due to an environment that will favor very high
instantaneous rain rates. Strong instability with highly anomalous
PWs (above the 99th percentile for late April) would support rain
rates in excess of 2 inches per hour. Hi-res guidance does, in
fact, show rain rates that high, particularly in far eastern
Texas, central Louisiana, and south-central Mississippi.

However, two key limiting factors may keep any higher rainfall
totals and flash flooding impacts relatively isolated. First, much
of the Marginal Risk area is in a severe to extreme drought with
1-hour flash flood guidance in the 3 to 4 inch range; so flash
flooding would tend to require high rain rates sustaining for
multiple hours or intersecting urban areas. Second, most hi-res
guidance indicates a steady progression to convective clusters and
lines with limited backbuilding or training, which would tend to
reduce the potential for sustained heavy rain for multiple hours.

We will continue to monitor for areas in which more concentrated
heavy rainfall may occur, given the overall environment. However,
confidence is not currently high enough to increase probabilities
in any specific area.

Lamers

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
825 PM EDT Wed Apr 29 2026
Day 2
Valid 12Z Thu Apr 30 2026 - 12Z Fri May 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN CENTRAL TEXAS...

21Z update... Minor expansions were made to the western and eastern
portions of the Hill Country, particularly along the Rio Grande to
reflect model trends and consistency with the new WPC forecast.
Still expecting very efficient rain rates given the environment
described below.

Campbell

The risk areas for Thursday and Thursday Night were generally
maintained from previous outlooks with minimal changes, refining
for better consistency with the latest rainfall guidance.
Increasing mid-upper level height falls, due to a strong shortwave
pushing through northern Mexico, should lead to a low-level mass
field response with increasing south to southeast inflow across
southern and central Texas. In general, the arrival of the better
synoptic forcing should be later in the period, which should
concentrate the main heavy rain and flash flood threat into
Thursday Night across the region.

By Thursday Night, strong low-level convergence and frontogenesis
is expected near the nose of the developing low-level jet. This is
depicted consistently across model guidance, despite some
variability in the positioning. This will coincide with anomalous,
deep moisture with PWs of 1.5 to 1.8 inches (around the 99th
percentile for late April) and narrowing CAPE profiles with lower
equilibrium levels. This fits a conceptual model for low-topped,
convective rain bands that have a more efficient warm rain process,
and could train and backbuild along the strong convergence axis.
The result could be several hours of persistent heavy rainfall in a
region of Texas that is less affected by the broader drought
conditions across the region, and with much more achievable flash
flood guidance benchmarks (around 3.5 inches in 3 hours).

We are concerned that the overall setup could merit a further risk
upgrade, but that may be more likely to occur the following day
(12Z Friday to 12Z Saturday) as the convective rain bands may not
get organized until very late in the forecast period, especially
after 06Z Friday. Therefore, while the event will get underway on
Thursday Night, impacts would be more likely to be realized in the
following forecast period, and the risk was held at the Slight
level for now in Central Texas.

Lamers

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
825 PM EDT Wed Apr 29 2026
Day 3
Valid 12Z Fri May 01 2026 - 12Z Sat May 02 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN CENTRAL AND
SOUTHEAST TEXAS AND THE CENTRAL GULF COAST...

21Z update... The latest guidance continues to depict organized
convection beginning during the tail end of the Day 2 period and
holding strong as it persists into the Day 3 period. Training
storms will likely be tracking from eastern Texas toward the
central Gulf states in proximity to the nearly stationary front,
with rainfall rates in excess of 1-1.5 inches/hour. Minor
reshaping of the Slight Risk was made for this update, particularly
on the eastern side for southern Mississippi and for southern and
central Alabama. There is also a growing signal for some of the
higher rainfall totals to streak from eastern Texas across central
Louisiana and into southwest Mississippi. While the Slight Risk
adequately covers the level of expected threat, this part of the
region may be on the higher end of the risk for flash flooding
concerns.

Campbell

Organized heavy rain bands may be ongoing at the start of the
forecast period (Friday morning) across Central Texas, described in
the Day 2 portion of this discussion. The Slight Risk area was
pulled back to the west to account for the possibility of ongoing
impacts; the rainfall may be split between the two forecast
periods, so the QPF for 12Z Friday to 12Z Saturday, viewed in
isolation, would tend to undersell the flash flood risk on Friday
morning in central Texas.

That was the main adjustment made to the outlook at this time. We
continue to see a strong signal for heavy rainfall from Texas into
the central Gulf Coast region. The rainfall forecast has increased
a bit with the major axis shifting south about 80 miles over the
past four forecast cycles. Models show a very strong low-level
convergence signal with a strong frontogenetic circulation shifting
east along the Gulf Coast during the period. This will be situated
in an environment with anomalously high PWs (above the 90th
percentile for late April; generally 1.5 to 1.8 inches) and narrow
CAPE profiles. The strong convergence should help focus efficient
convective rain bands and could lead to training of heavy rain
rates for multiple hours.

We will continue to monitor guidance trends for possible increases
in probabilities (and risk levels) if confidence grows in the
placement of the heaviest rainfall. Training rain bands in that
environment could easily lead to several inches of rain in just a
few hours. While much of the Slight Risk area is experiencing
drought conditions, that can be overcome for flash flooding impacts
if heavy rain rates are prolonged enough in a given location.
Therefore, the key to any increases in ERO probabilities would be
much greater confidence in placement of training rain bands. For
now, the Slight Risk highlights the general area where this is
possible, given available guidance and the overall parameter space.

Lamers

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

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
214 PM EDT Wed Apr 29 2026

Valid 00Z Thu Apr 30 2026 - 00Z Sun May 03 2026

...Central & Southern Rockies...
Days 1-3...

Expansive surface high pressure digging through the middle of the
country will drive a strong cold front southward all the way to the
Mexican border and Gulf Coast. Behind this front, cool air will
flood through the middle of the country, with post-frontal easterly
flow banking into the Central Rockies beginning Wednesday night and
persisting through Thursday to produce upslope flow into the
terrain.

As this occurs, synoptic ascent will begin to intensify over the
Central Rockies as well in response to interacting mid-level
impulses forcing a positively tilted, longwave trough, to drift
east late this week and into the weekend. This will force ascent
through height falls and the diffluent LFQ of a corresponding
subtropical jet streak pushing eastward across the southern tier of
the CONUS. Additionally, since the trough axis lags to the west,
moisture will continually funnel overhead on mid-level SW flow from
the Pacific, manifesting as large areas of precipitation where
forcing overlaps this moisture plume.

This precipitation will fall in the form of snow above generally
8000 ft, but locally snow levels could fall to below 7000 ft at
times, especially during the period of heaviest precipitation or as
the trough axis swings overhead to lower thicknesses. This will
keep the heaviest snowfall accumulations outside of the populated
I-25 corridor of CO/NM, except in the higher elevations of the
Palmer Divide and Raton Mesa where some light snowfall is expected
as reflected by WPC probabilities that are generally 50-70% for 4+
inches in these areas. This will result in hazardous driving across
these portions of I-25 as reflected by 30-50% probabilities of at
least minor impacts from the WSSI-P.

The heaviest accumulations, which are expected (>70% chance) to
exceed 12 inches before snow wanes quickly Friday evening, are
forecast in the higher elevations of the Front Range and Sangre de
Cristo Mountains, as well as the eastern portions of the San Juans.
Locally 2+ feet is possible (10-30% chance) in the highest peaks,
including Pike's Peak and along the Wet Mountains west of Pueblo,
CO.


The probability for significant icing over one-tenth of an inch is
less than 10 percent across the CONUS.


Weiss

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 PM EDT Wed Apr 29 2026

Valid 12Z Sat May 02 2026 - 12Z Wed May 06 2026


...Overview...

Several disturbances rotating around a persistent upper level
closed low centered over Ontario and Quebec will help to reinforce
broadly deep troughing across the eastern U.S. this weekend into
next week. This pattern typical of springtime will likely keep
conditions cool and unsettled across parts of the Northeast, Mid-
Atlantic, Great Lakes, and Upper Midwest. Meanwhile, a weekend
frontal system with plenty of moisture will threaten portions of
the Southeast and Florida with heavy rain and isolated flooding
concerns. Then another Pacific low tries to push inland late in the
weekend into early next week, possibly bringing some low elevation
rain and mountain snow showers to parts of the West.


...Guidance/Predictability Assessment...

A fairly stable mid/upper level pattern is expected to persist
through the medium range period, featuring a large upper low and
broad troughing across the eastern U.S., and a developing Rex block
across the western U.S. The latest guidance continues to have a
good handle on the overall pattern evolution through the period,
but still with plenty of uncertainty in the details. The main
sources of uncertainty deal with several smaller scale waves/energy
rotating around the large parent upper low spinning over southeast
Canada, as well as how quickly the cut-off Pacific low portion of
the Rex block pushes inland over the Southwest. An equal model
compromise between the GFS, ECMWF, CMC, UKMET, and EC-AIFS sufficed
for the first half of the forecast period, shifting towards more
weighting on the ensemble means for the latter half. This approach
remains in line with previous WPC forecast as well as the 13z NBM,
which served as a good starting point for the WPC Day 4-7 sensible
weather grids.


...Weather/Hazards Highlights...

An occluding low pressure system pivoting across southeast Canada
will continue to foster cool, breezy, and showery conditions over
parts of the Northeast through the weekend. Some light snow may
fall across the higher elevations of northern New England and the
interior Northeast as colder air wraps in on the backside of the
low, but any accumulations are expected to be minimal. Additional
disturbances rotating around the primary low over southeast Canada
may push a few cold fronts and chances for showers into the Upper
Midwest, Great Lakes, and Northeast later this weekend into next
week, keeping temperatures near to below seasonal norms. Chilly
nighttime lows may also lead to frost and freeze concerns over
parts of the Ohio Valley, Mid-Atlantic, and central Appalachians
this weekend as well.

The developing frontal system that is expected to bring heavy rain
and potential flooding concerns from Texas to the Lower
Mississippi Valley and Deep South Thursday and Friday will shift
eastward into the Southeast on Saturday. As the frontal wave fueled
by still impressive moisture and forcing tracks towards the Mid-
Atlantic coast, a trailing cold front will trigger clusters of
thunderstorms capable of producing heavy rainfall from the
Southeast into Florida. With much of the region in severe drought,
and after coordination with the WFOs, restricted the Day 4/Sunday
ERO to just far southeast Georgia and northern Florida where the
better moisture anomalies and instability will be present. This
trims out much of the remainder of the Southeast where rainfall
should be more beneficial. On Sunday, the cold front that follows
in the wake of the strengthening coastal low moving out to sea may
stall across Florida. Should this occur, the stalled frontal zone
would then become a focus for additional heavy rain given plentiful
moisture pooling along the boundary. Thus, a Day 5/Sunday Marginal
Risk ERO continues for much of central Florida.

A slow-moving Pacific low spinning off the coast of California
late this weekend should push across California and the Great Basin
during the first half of next week. There remains some uncertainty
with how quickly the low will advance inland, but moisture will
likely be drawn in to support scattered low elevation rain and
mountain snow showers across the West, along with cooler
temperatures following several days of unseasonable warmth.


Santorelli/Miller


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, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages are at:

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