Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Sat Oct 24 2026

Valid 00Z Sun Oct 25 2026 - 00Z Tue Oct 27 2026

...A Slight Risk of excessive rainfall from portions of New Mexico to
southern Colorado and nearby High Plains through Saturday night, shifting
slightly eastward into the southern High Plains on Sunday...

...A Slight Risk of severe thunderstorms from western Texas to southern
New Mexico through Saturday night...

...Heavy rain and excessive rainfall threats linger near the east coast of
Florida Peninsula...

An amplified weather pattern featuring a deep upper-level low over the
Desert Southwest sliding eastward against a strong ridge of high pressure
anchoring across the South will continue to feed subtropical moisture into
the southern Rockies and southern High Plains through the next couple of
days. Under this pattern, New Mexico will remain under the threat of
additional heavy rainfall from organized lines of showers and
thunderstorms through tonight. Areas receiving antecedent heavy rain are
the most vulnerable to flash flooding. In addition, the Storm Prediction
Center is highlighting areas from western Texas to southern New Mexico for
a slight risk of severe thunderstorms through tonight. By Sunday, the
heavy rain threat is forecast to shift only slightly to the east into the
southern High Plains under this slow-moving weather pattern. From Sunday
night into Monday, a low pressure wave is forecast to form over the
central High Plains and move northeast toward the northern Plains. A swath
of rain will gradually overspread the northern Plains, with embedded
thunderstorms ahead of the low pressure center, bringing 1 to locally 2
inches of soaking rain area-wide by Monday evening. The low pressure wave
will also drag colder air from the north, which could change the rain to
wet snow across the western portion of the Dakotas beginning Monday
morning.

Meanwhile, persistent easterly flow on the south side of a large and
strong high pressure system under the slow-moving weather pattern will
continue to feed Atlantic moisture toward the Sunshine State. This will
maintain a threat of heavy rainfall for the east coast of the Florida
Peninsula. WPC highlights a slight risk of excessive rainfall for
southeastern Florida on Sunday, lowering to a marginal risk on Monday.

Across the Pacific Northwest, a low pressure system is forecast to move
onshore and bring a round of rain area-wide, with embedded thunderstorms
possible on Sunday. The rain is expected to penetrate further inland
across Oregon, reaching into Idaho on Monday.

Elsewhere, under the amplified and slow-moving weather pattern, cooler
than normal temperatures are expected to prevail along the East Coast and
down into portions of the Gulf Coast states. In contrast, return flow from
the south will bring much above normal temperatures up the Plains states
and into the Midwest toward the Great Lakes through the next couple of
days. Meanwhile, dry weather will prevail across the Southwest.


Kong


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
230 PM EDT Sat Oct 24 2026

Valid 12Z Tue Oct 27 2026 - 12Z Sat Oct 31 2026


...Overview...

An upper trough will be atop the northwestern U.S. as the medium
range period begins Tuesday, with embedded shortwaves providing
rain and snow to the Pacific Northwest, northern Rockies, and
across the Upper Midwest as some energy pivots east. There is
increasing model agreement that an upper low will develop atop the
Pacific Northwest and British Columbia Wednesday-Thursday,
maintaining the same type of general flow pattern. Downstream upper
ridging will allow for warmer than average temperatures to spread
across much of the eastern half of the U.S. through the week.
Rounds of rain and thunderstorms are possible across the south-
central U.S. with favorable flow aloft. Into late week, upper
troughing is forecast to deepen in the West, supporting
precipitation chances over parts of the region. Overall, weather
across the lower 48 does not appear widely hazardous next week.


...Guidance/Predictability Assessment...

Models continue to show good overall agreement with the large
scale pattern across the country next week, with generally only
minor smaller scale spatial and temporal differences noted. The
differences in these details are more apparent with the positions
of a series of shortwaves spanning from the northwestern U.S. to
the central/northern Plains and Upper Midwest. Some of this energy
eventually shifts across the Great Lakes/Northeast as the week
progresses, with typical spread. The mid/upper pattern spanning
from the eastern Pacific into the Pacific Northwest, which models
initially struggled to resolve, now appears locked in with a
consensus for a Pacific Northwest/BC upper low Wednesday into
Thursday. Downstream ridging also seems well predicted. By Friday
and Saturday, some southern stream energies are forecast to pivot
around the base of the Northwest upper low/trough, which should
deepen the upper trough overall in the West. There are still some
model variations on the handling of these shortwaves and the exact
depth and position of the trough axis, but the overall pattern
seems fairly well aligned at this time range all things considered.

Given reasonably good model agreement on the large scale, used a
multi-model blend of the dynamical and AI guidance through much of
the period. Included some ensemble means in the fronts/pressures
forecast by the latter part of the period to smooth out individual
model differences.


...Weather/Hazards Highlights...

Multiple rounds of rain and higher elevation snow are forecast for
the Pacific Northwest across the northern Great Basin and Rockies
next week under a couple of upper troughs. Shortwaves in the
northern tier will also support precipitation in the north-central
U.S., and some snow could mix in at times even in lower elevations
of the northern Plains. Farther south, rain and thunderstorms are
possible in the southern/central Plains. Rain totals look to be
light through midweek, but may increase by later next week.
Meanwhile, broadening and deepening upper troughing across the West
may also direct more focused moisture and thus precipitation
chances into parts of the Four Corners states, but California is
starting to lean drier. Showers and thunderstorms could also affect
at least the east coast of Florida in easterly flow behind a
stalled front farther south.

Warmer than average temperatures are expected for portions of the
central and eastern U.S. from day to day under mean upper ridging.
Highs in the 70s are forecast as far north as the Mid-Mississippi
and Ohio Valleys. Temperatures should be near average to slightly
below average for highs in the western U.S. next week.


Tate/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

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
445 AM EDT Sat Oct 24 2026

Valid 00Z Sun 25 Oct 2026 - 00Z Sun 01 Nov 2026

An area of low pressure dropping south well to the northeast of
the islands will disrupt the trade winds to an extent over the next
couple days, although still expecting a steady northeasterly
breeze across the state. Within this flow we should see a
continuation of periodic showers across the windward areas of the
Big Island and Maui.

More impactful weather is likely to impact portions of the state
by Tuesday into Wednesday as an area of low pressure well west of
the islands moves east. Regardless of the state of this low, a
trough axis extending east of it should help focus an increasing
rainfall threat. While models continue to disagree on the exact
strength/track of this low, they all generally depict this trough
axis and PWs increasing towards 2.5", with a mid level trough and
upper level jet streak increasing forcing across the region. There
has been enough model and run to run agreement in this overall
setup to indicate confidence is increasing in a heavy rainfall
and flash flood risk Tuesday into Wednesday. However confidence on
the details, such as exact timing/location/magnitude of the
threat remains lower. The 00z GFS and ECMWF are very aggressive in
bringing a swath of heavy rainfall across the central islands,
and while this is a plausible scenario, the ensembles and past
deterministic runs indicate this magnitude of rain is not locked
in. Thus we will have to continue to monitor trends over the
coming days.

The pattern Thursday into Saturday is uncertain. While the most
organized heavy rainfall threat should diminish by Thursday,
there is disagreement in the guidance on whether anomalous
moisture and a wet pattern continues, or if some drier air
advects in and we transition to a more typical trade pattern.

Chenard

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 PM EDT Sat Oct 24 2026
Day 1
Valid 16Z Sat Oct 24 2026 - 12Z Sun Oct 25 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
WEST TEXAS, NEW MEXICO, AND COLORADO INTO FAR WESTERN KANSAS...

...16Z update...

Relatively minor changes were made to the outlook for this update
across western CO/NM with a westward expansion of the Slight Risk
to cover much of the San Juan Mountains into portions of
northwestern NM. This was due to early morning convective
development noted on 15Z satellite/radar across northwestern NM
into southwestern CO out ahead of a slow moving closed low across
the Southwest. Continued thunderstorm development is anticipated
over this region during the day today with increasing instability
resulting in multiple rounds of heavy rain. Given ongoing
hydrologic sensitivities over the region, the addition of an inch
or two of rain could exacerbate ongoing flooding in the vicinity of
the western CO/NM border as seen in the 12Z HREF/REFS with 24 hour
neighborhood (40 km) probabilities of exceeding 2 inches in the 50
to 80 percent range.

Elsewhere, the Slight and Marginal risks over southwestern NE and
northwestern KS were pulled back to the southwest a bit given an
expected lack of instability. The latest model consensus indicates
MUCAPE values staying generally below 250 J/kg through Sunday
morning and the 12Z HREF/REFS show neighborhood (40 km)
probabilities of exceeding 2 inches of rain in 24 hours to be less
than 1 percent where the risk areas were removed.

Otto

...previous discussion follows...

...West Texas to the Southern/Central High Plains...

An upper level low will split off from the main upper trough over
the southwestern U.S. early this morning. This feature will create
favorable conditions downstream for scattered to widespread
convection to develop from West Texas and New Mexico into the
southern and central High Plains, and convection will likely be
enhanced in coverage and intensity by an upper level shortwave
lifting north across the region this afternoon and evening.
Additionally, a strengthening south-southeasterly jet ahead of the
system will increase moisture transport into the region, and
instability will combine with this anomalous moisture to create a
heavy rainfall threat.

A Slight Risk of excessive rainfall was maintained for much of
eastern New Mexico and southeastern Colorado and portions of West
Texas and western Kansas. This area is expected to see the highest
rainfall totals ranging from 1.5-3 inches, with higher amounts
expected in portions of northeastern New Mexico and southeastern
Colorado where the HREF and REFS show 50-75% chance of exceeding 3
inches in 24 hours. Rainfall rates in this region may reach 1-1.5
inches per hour, rivaling flash flood guidance, and could lead to
scattered instances of flash flooding. Thankfully, the heaviest
rainfall today should be displaced to the east of where the
heaviest rain fell yesterday, but portions of north-central New
Mexico and south-central Colorado have been included in the Slight
Risk area to account for an elevated flash flood threat where
locally heavy rain may fall over already saturated soils.

The Slight Risk area also extends south into southeastern New
Mexico and West Texas where the environment will be favorable for
strong, organized convection later today. This area will see the
highest CAPE and wind shear values this afternoon, and the
vertically veering wind profile will be conducive for supercell
development. Any supercells that develop will be capable of
producing locally heavy rainfall that could cause flash flooding.
These cells should be fairly quick-moving, which should help to
somewhat limit the flash flood risk. The surrounding Marginal Risk
area was expanded in West Texas to account for the potential
eastward progression of convection this evening and for an upward
trend in hi-res model QPF in this area.

...Four Corners region...

A Marginal Risk of excessive rainfall extends back into the Four
Corners region and includes portions of eastern and southern Utah
and northern Arizona where convection in the vicinity of the upper
low may result in isolated instances of flash flooding. Convection
in this area should be fairly slow moving, and although snow levels
will be dropping, they should remain high enough to allow for
heavy rainfall. Models show some instability developing across Utah
and Arizona during the afternoon hours, and there should be enough
moisture to support widely scattered convection. Given the
preceding days of heavy rainfall leading up to Saturday, the region
may be more sensitive to additional heavy rainfall.

...East Coast of Florida...

A mid/upper-level low will slowly move south over the Atlantic
parallel to the Florida East Coast, which will generate scattered
convection over the Atlantic that will migrate onshore with strong
northeasterly flow on the northern and western sides of the
circulation. A plume of anomalous moisture with PWATs of 1.3-1.5
inches will be aimed onshore by the low circulation and gradually
shift down the coast throughout the day. The moist and unstable air
mass will allow for heavy rainfall rates to develop and coastal
convergence will focus rainfall over the urban I-95 corridor, which
has been highlighted with a Marginal Risk of excessive rainfall.
Isolated instances of flash flooding will be possible, especially
in urban, low-lying, and poor drainage areas.

Dolan


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 PM EDT Sat Oct 24 2026
Day 2
Valid 12Z Sun Oct 25 2026 - 12Z Mon Oct 26 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS AND SOUTHEAST FLORIDA...

...21Z update...

...Central and Southern High Plains...

The Slight Risk was extended southward from the TX/OK Panhandles
into southeastern NM and far western TX (just east of El Paso).
This was due to forecasts for higher instability (500-1500 J/kg
MLCAPE) over these regions which will be capable of supporting
higher rainfall rates. While better synoptic scale forcing will be
to the north with an ejecting shortwave, a lingering surface trough
axis/weak dryline will help to focus afternoon/evening
thunderstorms with potential for repeating/training due to largely
unidirectional southwesterly flow in the LFC-EL layer. There
remains some question on the coverage of cells but antecedent
rainfall from Saturday into Sunday morning will be a factor for
producing excess runoff. 12Z HREF/REFS neighborhood (40 km)
probabilities for exceeding 1 inch of rain in an hour are greatest
within the Slight Risk area extending from southeastern
CO/southwestern KS into the northwestern TX Panhandle, eastern NM
and far western TX (30-50 percent).

Farther north, forecast MUCAPE from the 12Z members of the HREF
showed values mostly below 500 J/kg throughout the 24 hour period
and more often, far less than 500 J/kg. This is reflected in the
12Z HREF/REFS neighborhood (40 km) probabilities for exceeding 1
inch per hour which are less than 15 percent where the Slight Risk
was trimmed but a Marginal Risk remains over portions of
northwestern KS. Outside of smaller maxima for exceeding 2 and 3
inches over the 24 hour period, the 12Z HREF/REFS neighborhood (40
km) probabilities showed the largest regional max for 2 and 3+
inches/24 hours to be centered from northeastern NM into the
western TX/OK Panhandles.

...East Coast of Florida...

Fairly good model agreement exists with the setup across FL with
25-35 kt of northeasterly 925-850 mb winds and a relative surge in
moisture that is in place at the start of the period. 12Z models
showed precipitable water values of 1.5 to 1.8 focused mostly over
the southeastern Peninsula along with the greatest instability
across the state, containing ~500 to 1000 J/kg MLCAPE. Moisture is
forecast to fluctuate through Monday morning along the east coast
of FL, remaining near average for late October. Repeating rounds
and brief training of showers/thunderstorms are expected to result
in isolated high rainfall totals. The 12Z HREF/REFS showed 40-60
percent neighborhood (40 km) probabilities of exceeding 3 inches
across southeastern FL over the 24 hour period ending Monday
morning along with up to 15 percent chances for exceeding 5 inches
near the coast or just offshore.

Otto

...previous discussion follows...

...Central and Southern High Plains...

The cutoff low will gradually progress northeastward, resulting in
an expanding region of precipitation ahead of the system from West
Texas through the southern and central High Plains. Similar to the
setup on Saturday, anomalous moisture will stream ahead of the
system into the Plains under favorable upper level conditions for
scattered to widespread convection. The best instability should be
focused over New Mexico and Texas, but there should be enough
instability extending into the High Plains to support deeper
convection with locally heavy rainfall.

The highest flash flood threat will likely be located over
portions of northeastern New Mexico, southeast Colorado, western
Kansas, and the Oklahoma and Texas panhandles where there is a
Slight Risk of excessive rainfall. There is still quite a bit of
uncertainty surrounding rainfall totals, but the general consensus
is for the highest amounts over the southern and central High
Plains, and this is also where the REFS is flagging the highest
probabilities for heavy rainfall. The western side of the Slight
Risk area is where there is a chance that the heavy precipitation
footprint may overlap with areas forecast to receive heavy rainfall
on Saturday, which would make the area more susceptible to flash
flooding with any additional rainfall.

The broader Marginal Risk area surrounding the Slight Risk area
was expanded in this forecast cycle to include more of southeastern
New Mexico and West Texas. This region will have the best
ingredients for heavy rainfall (CAPE greater than 1000 J/kg and
PWATs of 1-1.5 inches) but will be slightly displaced from the best
synoptic forcing with the main low. Any convection that develops
in this area will have the potential to produce locally heavy
rainfall. Given vulnerable terrain in southern New Mexico and heavy
rainfall received yesterday and expected today, the expansion of
the Marginal Risk area was justified. Soils over portions of Texas
will not be as saturated, but given the favorable setup could still
see a localized flash flood threat. The Marginal Risk area was
also trimmed on the northern side to remove some of Nebraska and
South Dakota where rainfall rates will be limited due to a lack on
instability and where rain should be more stratiform in nature.

...East Coast of Florida...

The mid/upper level low sliding down the coast will stall
southeast of Miami, which will result in a prolonged period of
moist, onshore flow across Southeast Florida. Showers and storms
will form over the Atlantic and move over the Florida coast, which
will result in heavy rainfall focused along the I-95 corridor. The
heavy rainfall threat will shift south throughout the day, with the
highest rainfall totals expected to accumulate over Southeast
Florida once the system stalls. There is a Marginal Risk of
excessive rainfall for much of the I-95 corridor south of
Jacksonville and a Slight Risk for the I-95 corridor south of
Melbourne. The Slight Risk area was expanded south to include more
of the Miami metro area based on the latest model trends in QPF.
Scattered instances of flash flooding will be possible, especially
in urban, low-lying, and poor drainage areas.

Dolan


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 PM EDT Sat Oct 24 2026
Day 3
Valid 12Z Mon Oct 26 2026 - 12Z Tue Oct 27 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL AND SOUTHERN HIGH PLAINS AND SOUTHEAST FLORIDA...

...21Z update...

...Central and Southern High Plains...

Only minor adjustments were made to the previous Marginal Risk
area across the southern High Plains.

There is good agreement in the 12Z models that the upper
trough/closed low over CO/WY at the start of the period (Monday
morning) will lift northeastward into the northern Plains through
Tuesday morning. An axis of above average precipitable water
containing standardized anomalies of 1 to 3 (via the 12Z GFS) will
be in place early Monday morning from far western TX into western
KS, but these values are expected to gradually lower beyond 00Z as
an upper trough axis swings through the southern Plains. A remnant
surface trough axis/weak dryline will extend southwestward from
western KS into eastern NM and far west TX (near El Paso). This
boundary and the unstable environment extending to its east will
serve as a focus for showers/thunderstorms with a likely diurnal
max in the late afternoon/evening. Peak hourly rainfall of 1-2
inches seems likely with the flash flood threat potentially
enhanced due to antecedent rainfall from previous days.

...Southeast Florida...

No changes to the existing Marginal Risk were made for this
update.

The QPF signal in the models is not as high over eastern FL for
Monday into Tuesday as compared to QPF ending Sunday and Monday
morning, however, a lower end flash flood threat looks to remain
over mainly southeastern Florida. Southeastern FL is forecast by
the 12Z model consensus to maintain 500-1000 J/kg MLCAPE focused
closest to the coast which may still allow for localized heavy
rainfall in the urban corridor.

Otto

...previous discussion follows...

...Central and Southern High Plains...

The upper level cutoff low will progress further, tracking across
the north-central U.S. on Monday with a trailing frontal zone
extending back across the central and southern High Plains.
Scattered convection is expected to develop ahead of the system and
will be able to tap into moisture flowing in from the Gulf and
instability in the vicinity of the front. A shortwave is expected
to move across the region on Monday and a strengthening jet along
the frontal boundary will place the southern High Plains in the
right entrance region, both of which should provide additional
support for convective development. Compared to previous days,
model QPF totals are modest, but the ingredients will be in place
for at least a localized heavy rainfall threat. Therefore, the
inherited Marginal Risk area was continued for the central and
southern High Plains.

...Southeast Florida...

Northeasterly onshore flow will continue across Southeast Florida,
but the low pressure system will gradually weaken, resulting in
precipitation tapering off on Monday night. Given heavy rainfall
expected in Southeast Florida on Sunday, a Marginal Risk was
maintained to account for isolated flash flood potential with
locally heavy rain falling over saturated soils.

Dolan

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 PM EDT Sat Oct 24 2026
Day 4 and Day 5
Valid 12Z Tue Oct 27 2026 - 12Z Thu Oct 29 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Pereira

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 PM EDT Sat Oct 24 2026
Day 4 and Day 5
Valid 12Z Tue Oct 27 2026 - 12Z Thu Oct 29 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Pereira

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
321 PM EDT Sat Oct 24 2026

Valid 00Z Sun Oct 25 2026 - 00Z Wed Oct 28 2026

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

An upper low over northwestern Arizona this evening will lift
northeastward across the Four Corners overnight. Southerly flow in
advance of the low will bring moderate precip rates and high snow
levels over Colorado around 9000ft tonight as rates decrease under
height falls. The probabilities for an additional 6 inches of snow
after 00Z are highest in the higher Sangre de Cristos and
especially the higher San Juan Mountains.


...Northern Plains...
Days 2-3...

The Four Corners low will mostly open to a trough by Monday and
eject across the northern Plains. With surface low pressure moving
across eastern SD Monday night, enough comma head expansion of
precip should occur to have some snow bands on the outer northwest
side of the precip shield. This could intersect with the Black
Hills and could also have dynamic enough banding for some snow
accumulation in northwestern South Dakota and south central North
Dakota. Temperatures are marginal, but any snow that falls before
sunrise would have a better chance of accumulating. Most likely
forecast is for a broad T-0.5" snow with some potential for an axis
of 1-2" from the Black Hills northeastward. The probability of at
least 2" from the Probabilistic Precipitation Portal is about
20-55% along the ND/SD border southwest of Bismarck, but the 90th
percentile is around 4".

...Northern Rockies...
Day 3...

An upper low along the WA/OR coast Monday will push inland and
cross the Divide early Tuesday, spreading valley rain and mountain
snow to Wyoming, Idaho, and western Montana. Snow levels will hover
around 5000-7000ft through Tuesday evening with snow continuing
into early Wednesday. The probability of at least 6 inches of snow
by 00Z Wednesday is >50% above about 8000ft where liquid amounts
will be highest as well.


For Days 1-3, the probability of significant ice across the CONUS
is less than 10 percent.


Fracasso/Jackson

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
230 PM EDT Sat Oct 24 2026

Valid 12Z Tue Oct 27 2026 - 12Z Sat Oct 31 2026


...Overview...

An upper trough will be atop the northwestern U.S. as the medium
range period begins Tuesday, with embedded shortwaves providing
rain and snow to the Pacific Northwest, northern Rockies, and
across the Upper Midwest as some energy pivots east. There is
increasing model agreement that an upper low will develop atop the
Pacific Northwest and British Columbia Wednesday-Thursday,
maintaining the same type of general flow pattern. Downstream upper
ridging will allow for warmer than average temperatures to spread
across much of the eastern half of the U.S. through the week.
Rounds of rain and thunderstorms are possible across the south-
central U.S. with favorable flow aloft. Into late week, upper
troughing is forecast to deepen in the West, supporting
precipitation chances over parts of the region. Overall, weather
across the lower 48 does not appear widely hazardous next week.


...Guidance/Predictability Assessment...

Models continue to show good overall agreement with the large
scale pattern across the country next week, with generally only
minor smaller scale spatial and temporal differences noted. The
differences in these details are more apparent with the positions
of a series of shortwaves spanning from the northwestern U.S. to
the central/northern Plains and Upper Midwest. Some of this energy
eventually shifts across the Great Lakes/Northeast as the week
progresses, with typical spread. The mid/upper pattern spanning
from the eastern Pacific into the Pacific Northwest, which models
initially struggled to resolve, now appears locked in with a
consensus for a Pacific Northwest/BC upper low Wednesday into
Thursday. Downstream ridging also seems well predicted. By Friday
and Saturday, some southern stream energies are forecast to pivot
around the base of the Northwest upper low/trough, which should
deepen the upper trough overall in the West. There are still some
model variations on the handling of these shortwaves and the exact
depth and position of the trough axis, but the overall pattern
seems fairly well aligned at this time range all things considered.

Given reasonably good model agreement on the large scale, used a
multi-model blend of the dynamical and AI guidance through much of
the period. Included some ensemble means in the fronts/pressures
forecast by the latter part of the period to smooth out individual
model differences.


...Weather/Hazards Highlights...

Multiple rounds of rain and higher elevation snow are forecast for
the Pacific Northwest across the northern Great Basin and Rockies
next week under a couple of upper troughs. Shortwaves in the
northern tier will also support precipitation in the north-central
U.S., and some snow could mix in at times even in lower elevations
of the northern Plains. Farther south, rain and thunderstorms are
possible in the southern/central Plains. Rain totals look to be
light through midweek, but may increase by later next week.
Meanwhile, broadening and deepening upper troughing across the West
may also direct more focused moisture and thus precipitation
chances into parts of the Four Corners states, but California is
starting to lean drier. Showers and thunderstorms could also affect
at least the east coast of Florida in easterly flow behind a
stalled front farther south.

Warmer than average temperatures are expected for portions of the
central and eastern U.S. from day to day under mean upper ridging.
Highs in the 70s are forecast as far north as the Mid-Mississippi
and Ohio Valleys. Temperatures should be near average to slightly
below average for highs in the western U.S. next week.


Tate/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