Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
302 PM EDT Wed Mar 19 2025

Valid 12Z Sat Mar 22 2025 - 12Z Wed Mar 26 2025


...Overview and Guidance/Predictability Assessment...

Progressive flow with activity over the northern tier continues
into Sunday before amplification through early next week with the
development of a warming/building West Coast ridge and a
cooling/deepening and unsettling east-central U.S. trough.

The main low pressure feature is a trough that rounds a Gulf of
Alaska low Thursday night, crosses Vancouver Island Friday, then
amplifies over the northern Plains Saturday night and deepens into
a low over the Great Lakes Sunday night that slows is reinforcing
into midweek as ridging amplifies over the west. Global guidance is
in good agreement with this low and the ridge through Monday night
with uncertainty rising with the timing and strength of the
reinforcing shortwave troughs rounding the Great Lakes low.

Forecast confidence remains above average overall with a
deterministic blend of the GFS/ECMWF/CMC/UKMET through Day 5 with
some GEFS/ECENS included for Days 6/7 (which is after input from
the UKMET ends). This blending is mainly in line with the National
Blend of Models and WPC continuity.

...Weather/Hazards Highlights...

Northern tier activity working with continental air masses results
in no excessive rainfall risk for the CONUS on Day 4/Saturday.

Ridge riding shortwave troughs shift from the northeast Pacific
into BC Sunday with a potent moisture plume to the south that
pushes across western WA. A Marginal Risk for excessive rain is
maintained for Day 5/Sunday coastal Washington as compounding
effects of multiple preceding bouts of precipitation may lead to
local runoff issues.

The amplifying low over the northern Plains into the Great Lakes
Sunday night draws broad scale Gulf moisture up the MS Valley and
support a heavy rain and a severe weather threat for parts of Mid-
South and lower MS Valley into the TN Valley. The Day 5 ERO
Marginal Risk area is maintained for the Lower Mississippi and
Tennessee Valleys. Enhanced rains then spread as a wavy cold front
sweeps across the Southeast/Eastern Seaboard Monday into Tuesday.

Meanwhile, reinforcing cold air wrapping around the main low
appears to support a heavy snow threat for the Great Lakes region
Sunday into Monday, possibly spreading over the northern and
interior Northeast into Monday and Tuesday with closed upper
low/trough approach and as triple-point low development is
additionally possible near the coast of New England.

Jackson


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
301 PM EDT Thu Mar 20 2025

Valid 12Z Sun Mar 23 2025 - 12Z Thu Mar 27 2025


...Overview and Guidance/Predictability Assessment...

Progressive upper flow into the weekend in two streams will
amplify into next week with the development of a warming/building
West Coast ridge and a cooling/deepening and unsettling east-
central U.S. trough.

Operational and ML models capture the evolution of the overall
synoptic pattern across the lower 48 for next week. All models are
in reasonably good agreement on the day 3 pattern, save for
several
00z GEFS members which depict a slower Central U.S. trough. This
trend continues through the rest of the period. Deterministic
guidance are more progressive than the ensembles and operational
AIFS with the upper low propagating through the Great Lakes region
on day 4. The upper pattern simplifies into mean troughing in the
East and mean ridging in the West beginning on day 5. A Euro-
centric general model blend is used from day 5 through 7.


...Weather/Hazards Highlights...

Shortwave troughs riding a Western ridge will shift from the
northeast Pacific into BC Sunday with a potent moisture plume to
the south that pushes across western WA. A Marginal Risk for
excessive rainfall is maintained only into Day 4/Sunday for
coastal Washington as compounding effects of multiple preceding
bouts of precipitation may lead to local runoff issues. Amplified
upper trough development and deep system genesis early-mid next
week should prove slow to approach the West Coast, but should
spread organized precipitation back into the Northwest in about a
week.

The amplifying low over the northern Plains into the Great Lakes
Sunday will draw broad scale Gulf moisture up the MS Valley and
support a heavy rain and a severe weather threat for parts of Mid-
South and lower MS Valley into the TN Valley. The Day 4/Sunday ERO
Marginal Risk area is maintained for the Lower Mississippi and
Tennessee Valleys. Enhanced rains then spread as a wavy cold front
sweeps across the Southeast/Eastern Seaboard Monday into Tuesday. A
WPC Day 5/Monday ERO Marginal Risk area was maintained to cover
lingering and training cell potential over the eastern Gulf Coast.

Meanwhile on the northern periphery of the expanding precipitation
shield, reinforcing cold air wrapping around the main deep low
appears to support a heavy snow threat for the Great Lakes region
Sunday into Monday, spreading over the northern and interior
Northeast into Monday and Tuesday with closed upper low/trough
approach and with coastal New England triple-point low development.

An amplifying ridge in the West will support an early return of
spring-like temperatures in the West next week. Highs are expected
to be between 15-30 degrees above average for much of the region.
There's increasing potential for widespread high/low records to be
tied/broken next Tuesday/Wednesday. This includes much of the
Desert Southwest, where some places may experience daytime highs
over 100 degrees.

Kebede/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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Fri Mar 21 2025

Valid 12Z Mon Mar 24 2025 - 12Z Fri Mar 28 2025


...Overview...

The early to middle part of next week will feature a large-scale
western U.S. upper ridge and eastern trough. The pattern should
flatten/progress some later in the week, as energy from an eastern
Pacific trough reaches into the West while the ridge moves into the
Plains/Mississippi Valley and the eastern troughing begins to lift
out. Expect very warm temperatures under the upper ridge with some
daily records possible over the West. The Great Lakes and East
Coast/Gulf Coast will see one episode of precipitation with a
Monday system with a possible Midwest wave on Tuesday potentially
spreading some moisture into the East by midweek. The upper
dynamics and leading front reaching the West will bring rain and
high elevation snow to the Northwest mid-late week. Meanwhile a
southern tier shortwave will bring a threat of locally heavy
rainfall to parts of the southern half of Texas late in the week.

...Guidance/Predictability Assessment...

Models and ensembles show good agreement on the large scale, but
still a lot of uncertainty in the details. There is good
consistency with the Eastern U.S. system on Monday-Tuesday, but
still spread with the next wave into the Midwest and towards the
Northeast. This second feature though has fairly low predictability
due to being very sensitive to small scale detail differences in
supporting shortwave energy. By mid to late week, some continued
spread as the next trough enters the West. Overnight ECMWF runs
were sharper than previous runs (and other guidance), so did not
put much weight on that solution in the blend today. CMC/ECMWF runs
are also faster than the GFS with the trough.

WPC blend for today favored the deterministic models early period,
trending towards slight majority ensemble means later in the
period. This maintained good continuity with previous WPC forecasts
as well.


...Weather/Hazards Highlights...

Low pressure tracking from the Great Lakes eastward early in the
week will produce some snow over far northern areas, with best
potential for meaningful accumulation on Monday over central and
northern New England. Expect rain farther south along the trailing
cold front. The Day 4/Monday Excessive Rainfall Outlook holds onto
a Marginal Risk area over parts of the Gulf Coast in light of
lingering training potential that is most prominently suggested in
the GFS. However other guidance is less enthusiastic QPF-wise and
it is a fairly progressive front, so would consider this a lower-
end threat at this time. Behind this system a weak wave may track
through the Midwest around Tuesday and then near the Northeast
coast by Wednesday. Any associated precipitation should be fairly
light and confidence in the system's evolution is below average at
this time.

Far northern parts of the West may see lingering precipitation on
Monday with most of the region dry by Tuesday. Upper trough energy
and a leading cold front will bring another round of rain and high
elevation snow into the Northwest and northern Rockies mid-late
week. There is some uncertainty over amounts and south and inland
extent.

Around Tuesday-Tuesday night some guidance hints at the potential
for very localized enhanced rainfall over parts of the southern
Plains, near the front trailing from the weak Midwest wave. This
potential activity is not sufficiently agreeable or organized in
the guidance to merit an ERO risk area at this time. Ground
conditions are also fairly dry over this region. Then the
combination of an approaching southern stream trough along with
moist easterly low level flow from the Gulf may increase the
chances for more organized and heavier rainfall over parts of
southern Texas late in the week.

The strong upper ridge over the West early-mid week will bring
well above normal temperatures to the region, with a broad area of
highs 10-20F above normal with locally higher anomalies. There will
also be potential for numerous daily records for highs/warm lows,
especially on Tuesday and Wednesday. Some places over the Desert
Southwest could get close to 100 degrees. As the upper pattern
shifts eastward somewhat later in the week, the West will cool down
while already above normal anomalies over the central U.S. will
increase. Areas over and near the central Plains should see highs
reach 20-25F above normal by Thursday-Friday. Mean troughing aloft
will keep most of the East near to slightly below normal for
temperatures.

Santorelli/Rausch


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
210 PM EDT Sat Mar 22 2025

Valid 12Z Tue Mar 25 2025 - 12Z Sat Mar 29 2025


...Overview...

An amplified western ridge/eastern trough upper pattern as of
Tuesday will gradually progress eastward while trending flatter, as
dynamics from a strong midweek upper trough (supporting a storm
system off the Pacific Northwest coast) push into the western half
of the lower 48. The mean ridge should reach the East by Friday or
Saturday. Expect very warm temperatures under the western upper
ridge through midweek with some daily records possible. Anomalous
warmth will then move into the Plains, followed by moderation
farther east. Upper dynamics and the leading front arriving from
the Pacific will bring rain and high elevation snow to the
Northwest mid-late week. A southern tier shortwave will support the
threat of locally heavy rainfall over parts of Texas late in the
week, with this moisture and additional Gulf inflow potentially
combining to spread a broader area of mostly rain over parts of the
Plains and east-central U.S. by the end of the week. A weak
Midwest wave on Tuesday may produce a band of mostly light
precipitation near its track that may extend offshore the Mid-
Atlantic/New England coast by Wednesday.


...Guidance/Predictability Assessment...

Most guidance is fairly agreeable with the large scale upper flow
pattern during the period, but continue to show differences in the
details and timing of systems. There continues to be timing
differences with the shortwave through the Midwest-East
Tuesday/Wednesday with the CMC on the slow side, and GFS slightly
fast. Prefer a solution closer to the ECMWF or UKMET which are more
in the middle. By Thursday, guidance continues to diverge for the
storm forecast to track offshore the Pacific Northwest and
amplitude of the upper trough nearing the West Coast with GFS runs
continuing to be flatter with the upper trough than most other
guidance. This spread expands inland across the western half of the
country during Friday- Saturday. GFS runs remain on the high side
of the spread for heights aloft with most other guidance showing
better defined shortwave energy but with increasing spread for
details. This tempers confidence in the exact details of low
pressure that should reach the central U.S. toward the end of the
week. As a result of these Western U.S. differences, the GFS tends
to lean on the slower side of the spread for the southern stream
shortwave forecast to reach into the southern Plains by Friday. To
note, the new 12z run of the GFS today (which was available after
the WPC forecast was generated), did trend slightly faster with the
Southern Plains wave and sharper with the Western trough.

The WPC forecast today leaned more heavily on the ECMWF early
period, with lesser contributions from other deterministic
guidance. Trended towards 70 percent of the ensemble means (with
the ECMWF) late in the period to mitigate the differences out West.
This maintained good continuity with the previous WPC forecast as
well.


...Weather/Hazards Highlights...

The Days 4-5 Excessive Rainfall Outlooks covering the period from
Tuesday through Wednesday night currently depict no risk areas but
there are a couple regions of interest for continued monitoring.
During Day 4 there are some guidance signals for localized heavy
rainfall potential over and west/northwest of the ArkLaTex region,
focused by a couple frontal boundaries and with increasing
afternoon instability. Drier than average ground conditions and
small-scale nature of this activity have favored no risk thus far,
but improved clustering on the heavier side of the range could
eventually merit an area. Then on Day 5 the Pacific system
affecting the West Coast may bring a brief period of enhanced
rainfall to the Pacific Northwest and northern California coast.
There is continued spread with magnitude and coverage (though with
most guidance suggesting higher amounts extending farther south
then GFS runs) while first-guess guidance is fairly muted with its
excessive rainfall potential for the time being. Again will monitor
guidance for improved clustering here.

Expect the southern tier shortwave nearing the southern Plains
after midweek to start generating rainfall near the Rio Grande
Valley on Wednesday with heavier activity likely reaching eastward
more into Texas by Thursday. Given dry soil conditions, much of
this will be beneficial rain but higher rates over more urbanized
areas may spur a local threat. Precipitation should push across the
West late in the week, with leading Gulf inflow helping to
increase the coverage and intensity of precipitation over the
Plains/east- central U.S. by Friday- Saturday. Most of this
precipitation should be rain but some wintry weather will be
possible near the Canadian border.

Earlier in the period, a weak wave that should track from the
Midwest to offshore the Mid-Atlantic/New England coast Tuesday-
Wednesday may produce a band of mostly light precipitation along
its path. The majority of this activity should be rain, though a
little snow is possible on the northern fringe of the moisture band
and in the Appalachians.

The strong upper ridge over the West early-mid week will bring
well above normal temperatures to the region, with a broad area of
highs 10-20F above normal with locally higher anomalies. There will
also be potential for numerous daily records for highs/warm lows,
especially during Tuesday-Wednesday. Some places over the Desert
Southwest could get close to 100 degrees. As the upper ridge shifts
eastward with time, the West will cool down while already above
normal anomalies over the central U.S. will increase. Locations
from the northern-central Plains into Midwest should see one or two
days of highs reaching 20-25F or so above normal by Thursday-
Friday. The East will see increasing coverage of highs 10-20F above
normal by Friday-Saturday after near to slightly below normal
readings Tuesday-Thursday.

Santorelli/Rausch


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
248 PM EDT Sun Mar 23 2025

Valid 12Z Wed Mar 26 2025 - 12Z Sun Mar 30 2025


...Overview...

Expect the amplified western ridge/eastern trough upper pattern
lingering into Wednesday to move steadily eastward while trending a
little flatter, as dynamics from a strong East Pacific upper
trough Wednesday-Thursday (supporting a storm system off the
Pacific Northwest coast) push into the western and central U.S.
With a slightly slower trend noted in the guidance, the mean ridge
should reach the East by next weekend. Expect very warm
temperatures under the western upper ridge through midweek or so
with some daily records possible. Anomalous warmth will then move
into the Plains, followed by moderation farther east. Upper
dynamics and the leading front arriving from the Pacific will bring
rain and high elevation snow to the Northwest mid-late week, with
another system possibly approaching by next Sunday. A southern tier
shortwave will support the threat of locally heavy rainfall over
parts of Texas late in the week. This moisture and additional Gulf
inflow may combine to spread a broader area of precipitation over
parts of the Plains and east-central U.S. late week into the
weekend, in association with Plains through Upper Midwest low
pressure.

...Guidance/Predictability Assessment...

Guidance continues to show good agreement on the large scale upper
pattern and progression, but a lot of uncertainty in the details.
A leading shortwave into the West from a deepened low off the
Pacific Northwest coast shows good agreement, but there is
continued question on timing and amplitude of a deeper trough into
the West later in the week. The GFS has trended slightly deeper in
recent days, but the last several runs of the CMC continues to be
the outlier as it eventually spins up a closed low over the Central
Plains next weekend. Better cluster of guidance suggests this
should be more of an open wave. Ahead of this though, there remains
uncertainty in the details of a southern stream shortwave into the
Southern Plains and Midwest later this week, which has impacts on
heavy rainfall potential across Texas. Then by next weekend
guidance shows spread with a front that reaches into the Mid-
Atlantic, likely with a pronounced temperature gradient.

The WPC forecast today was able to use a blend of the latest
deterministic guidance for Wednesday and Thursday, amidst good
model agreement. Began incorporating the ECENS/GEFS by Friday/Day
5, eventually reaching a 50/50 split of deterministic/ensemble
means by Day 7. Did not include the CMC in the late period blend
due to the outlier solution described above. Overall, this approach
maintained good continuity with the previous WPC forecast.

...Weather/Hazards Highlights...

From Wednesday into Thursday night the most prominent heavy
rainfall focus should be over portions of Texas by Thursday as
moist southeasterly low level flow from the Gulf interacts with an
upper shortwave crossing northern Mexico. Some activity may
initiate in the Day 4 period near the Rio Grande Valley but the
signal is diffuse enough not to merit any risk area in the
Excessive Rainfall Outlook. By Day 5 there is a much stronger
signal, though with typical spread for where the heaviest rainfall
axis will be. Overall the best overlap of guidance exists over
southern Texas. The Day 5 ERO maintains a broader Marginal Risk
area, with no embedded Slight Risk depicted yet due to initially
dry ground conditions and guidance spread. Improved clustering for
location and amounts in the heavier part of the envelope could
eventually merit an upgrade. Elsewhere, consensus amounts along the
Pacific Northwest coast in association with the Wednesday-
Thursday system have generally decreased somewhat from 24 hours
ago, while the signal for a potential band of enhanced rainfall
over the Mid Mississippi Valley ahead of a warm front is too
diffuse to warrant a risk area yet on Day 5.

Precipitation will spread across northern and central parts of the
West late this week, with Plains low pressure and its trailing
front eventually pushing the Texas rainfall eastward while
spreading a broader shield of moisture across the central and east-
central U.S. Some wintry weather will be possible over far
northern latitudes but otherwise most precipitation should be in
the form of rain. How much snow falls over the northern Plains next
weekend will depend on how strongly the Plains/Upper Midwest
system develops, with low confidence in specifics at this time. The
next Pacific system may increase precipitation along the West
Coast by next Sunday.

The weak wave forecast to track off the Mid-Atlantic/New England
coast on Wednesday may produce some light precipitation early but
most likely just near the coast.

The strong upper ridge over the West into Wednesday will bring
well above normal temperatures to the region, with a broad area of
highs 10-20F above normal with locally higher anomalies. There will
also be potential for numerous daily records for highs/warm lows,
especially during Wednesday. As the upper ridge shifts eastward
with time, the West will cool down while already above normal
anomalies over the central U.S. will increase. Locations from the
northern-central Plains into Midwest should see one or two days of
highs reaching 20-25F or so above normal by Thursday-Friday, with
best potential for some daily records over the central High Plains
on Thursday. The East will see near to slightly below normal
temperatures Wednesday-Thursday and then increasing coverage of
highs 10-20F above normal Friday into the weekend. However a front
reaching the Northeast/Mid-Atlantic may define a sharp gradient
between this warmth and cooler readings just to the north.

Santorelli/Rausch


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