Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
113 AM EDT Sat Jun 01 2024

Valid 12Z Sat Jun 01 2024 - 12Z Mon Jun 03 2024

...Excessive Rainfall threatens parts of the Central/Southern Plains,
Southeast and Mississippi/Ohio Valleys today...

...Severe Weather refocuses over the Great Plains this weekend...

...Southern Texas remains warmer than average through early next week...


A sequence of shortwave energies will support impactful weather across the
Central U.S. this weekend. Showers and thunderstorms will organize ahead
of a low pressure system over the Middle/Lower Mississippi Valley and
spread into the Southeast this morning and afternoon. Some storms may be
strong enough to produce heavy rainfall. A Slight Risk (at least 15%) of
Excessive Rainfall leading to Flash Flooding is in effect for portions of
Tennessee, Mississippi and Alabama today. Meanwhile, some dry-line storms
could turn severe over parts of the Central/Southern High Plains this
afternoon. The Storm Prediction Center issued a Slight Risk (level 2/5) of
Severe Thunderstorms for the aforementioned areas with supercells possibly
organizing into clusters and spreading into the Plains tonight. Severe
wind, hail and brief tornadoes are possible.

Another low pressure system emerging from the Rockies will bring a renewed
threat of severe weather to the Northern/Central Plains and Upper Midwest
on Sunday. A Slight Risk (level 2/5) of Severe Thunderstorms is in effect
from southeastern North Dakota to western Minnesota and down into central
Nebraska, where a line of severe storms may produce damaging wind gusts
and hail could be the main severe threats. There's also a Slight Risk (at
least 15%) of Excessive Rainfall leading to Flash Flooding over parts of
southern Minnesota, southeastern South Dakota, eastern Nebraska and Iowa
on Sunday.

Deep upper-level troughing will bring rain and cooler temperatures to the
Pacific Northwest on Sunday. Temperatures will remain above average across
southern Texas, while warmer conditions expand across the Great Plains
through early next week. Approaching shortwave energy and an upper low
locked in just off the Northeast Coast will support warmer than average
temperatures over the Northeast for the next several days.


Kebede


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EDT Sat Jun 1 2024

Valid 12Z Tue Jun 04 2024 - 12Z Sat Jun 08 2024

...Excessive heat likely to continue over southern Texas, while
heat builds in the West for the latter half of next week...


...Overview...

As the medium range period begins Tuesday, expect an upper-level
shortwave to track across the north-central U.S. along with a
surface low pressure/frontal system, spreading rain and
thunderstorms to much of the Mississippi Valley. This shortwave
trough will meet a somewhat blocky pattern farther east and
slow/deepen over the east-central U.S. late week into the weekend,
with rain chances gradually shifting toward the eastern U.S. along
and ahead of the cold front. Meanwhile an upper ridge atop Mexico
and southern Texas Tuesday will expand to affect much of the
western U.S. midweek and beyond, producing potentially hazardous
heat. Then an upper trough may approach the West Coast late week
but with uncertain timing.


...Guidance/Predictability Assessment...

Recent model guidance is more agreeable than it was a day ago
regarding the timing of the shortwave tracking near the
U.S./Canadian border Tuesday-Wednesday. This feature is likely to
form a closed upper low by Thursday near to northwest of the Upper
Great Lakes. Deterministic and AI models are more variable with the
placement of the upper low and the southern extent of the
resultant trough. The newer 00Z GFS/CMC end up reaching farther
south with the trough than the previous 12/18Z cycle, but the 00Z
ECMWF elongates the upper low west-east strangely by next Saturday.
Thus the details are still in question by late week/weekend with
this feature.

The relatively better agreement with the north-central to eastern
U.S. trough also yields better model consensus regarding the
western U.S. ridge, but uncertainties remain on the ridge's
periphery. The evolution of the eastern trough/low will affect the
ridge's extent north, with the greatest differences of ridging vs.
troughing arising in the north-central U.S. by Friday-Saturday.
Southern stream energy and possible closed upper low west of Mexico
through much of the period could play a role in the ridge's shape
on the southwest side. Then, there is model spread with timing of
troughing in the eastern Pacific approaching the Northwest late
week. The ECMWF is showing ridging strongly holding on in the
Northwest with the Pacific trough well west all the way through
Saturday, but EC-based AI/ML models indicate the trough farther
east. However, the GFS runs are well on the eastern side of the
envelope. A middle ground more like the ensemble means seemed best
for timing of that approaching troughing.

The WPC forecast utilized a multi-model deterministic blend early
in the forecast period given good agreement in the large scale
pattern at least. As the period progressed, transitioned to a blend
incorporating the GEFS/EC ensemble means to half Day 6 and more
Day 7, given the increasing spread and uncertainty.


...Weather/Hazards Highlights...

A vigorous shortwave and frontal system (anchored by southern
Canada low pressure) reaching the Dakotas into the Upper Midwest on
Tuesday will provide forcing and a focus for rain and
thunderstorms as instability abounds ahead of it. Smaller scale
shortwaves farther south should also track eastward and promote
scattered convection. A Marginal Risk is in place for the Day
4/Tuesday ERO for much of the Mississippi Valley and expanded a bit
into the Mid-South based on recent model trends. Some locations
within this area will be sensitive due to rainfall from prior days.
The best focus for widespread moderate to heavy rain is likely
across the Upper Midwest, but uncertainty in amounts and placement
as well as the effects of the rainfall precludes a Slight Risk
issuance at this time. Into Wednesday, convection is forecast to
shift east ahead of the cold front into the Great Lakes region and
Ohio and Tennessee Valleys, and a Marginal Risk is delineated for
those areas. For both days, the forward motion of the storms may be
a limiting factor for flooding to become too concerning. Steady
progression of the front will take rain chances into the East for
Thursday-Friday, with possible focus of heavier amounts from the
northern Mid-Atlantic into the interior Northeast where the best
forcing is.

Some lingering precipitation is forecast in the Northwest on
Tuesday before drying out midweek with the amplifying ridge aloft.
Gusty winds are possible in the northern Rockies behind the strong
southern Canada/northern tier U.S. surface low on Tuesday. Into
late week, some return flow of moisture is possible across the
southern/central Rockies and Plains, but with considerable
uncertainty in coverage and amounts of rain. The same can be said
of possible precipitation affecting the Northwest late week.

Next week will remain hot across South Texas westward through the
Rio Grande Valley, where the combination of hot temperatures into
the 90s and 100s as well as humidity will keep heat indices in the
upper 100s, locally 110+. Temperatures nearing or exceeding 100F
may stretch across the southern High Plains through Tuesday but
should moderate somewhat by midweek behind a frontal passage. Some
above normal temperatures are possible across the northern tier at
times. But the next big concern will be increasing heat across the
West as upper ridging builds in. Highs broadly will run 10-15
degrees above average, with even warmer anomalies of 15-20+ degrees
for the central California valleys and portions of the Great
Basin. Temperatures should reach over 100F across the central
California valleys, and near/over 110F in the Desert Southwest.
Scattered daily record high minimum and maximum temperatures are
possible. Per the Climate Prediction Center, this hot pattern could
continue into early next week.


Tate


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
332 AM EDT Sat Jun 01 2024

Valid 00Z Sun Jun 02 2024 - 00Z Sun Jun 09 2024

Breezy easterly trade winds are likely through the weekend and
into the first part of next week, as elongated surface high
pressure stays in place well north of Hawaii. Meanwhile aloft,
weak troughing possibly forming a closed upper low atop the state
this weekend could allow for some minor instability to develop,
increasing potential for showers. Showers should focus in
windward/mauka areas due to the trades. Models show above normal
moisture (precipitable water values) coming into the state
Monday-Wednesday as well.

By the latter half of next week, the elongated surface high is
likely to split north of Hawaii and decrease the pressure
gradient, lessening the trades and perhaps allowing for a land/sea
breeze pattern to set up. A somewhat drier pattern looks to
develop as well, as mid-upper heights rise.


Tate

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
848 PM EDT Fri May 31 2024
Day 1
Valid 01Z Sat Jun 01 2024 - 12Z Sat Jun 01 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
THE UPPER MIDWEST AND SOUTHEAST U.S. INTO THE LOWER/MID
MISSISSIPPI VALLEY...

...01Z Update...
With the 0100 UTC update, included a targeted Slight Risk area
across portions of central-southcentral TX, including much of the
Austin and San Antonio metros and Hill Country, owing to the
expanding cluster of convection moving into an area of untapped
deep-layer instability (mixed-layer CAPEs 2000-2500 J/Kg).
Moreover, recent heavy rainfall has significantly lowered FFGs in
this region, with 1hr FFG as low as 1-1.5". For further details,
please refer to the latest Mesoscale Precipitation Discussion or
MPD #361, which can be accessed at
www.wpc.ncep.noaa.gov/metwatch/metwatch_mpd.php.


...20Z Update...
Based on the latest observational and mesoanalysis trends, have updated
the Day 1 ERO to (a) add a Slight Risk area across northeast NE-
Southeast SD into northwest IA and much of southern MN, and (b)
pare much of the Slight risk west of AR-LA. Despite the earlier
heavy rainfall/antecedent wet soils, shortwave ridging is limiting
the converage of any renewed convection, despite the airmass
recovery (destabilization) this afternoon. Per the latest high-res
CAMs (HRRRs and 18Z HREF), less-organized or spottier convection
later this afternoon and evening may result in additional localized
instances of flash flooding, though mainly south of where the
heaviest rainfall had occurred over the past 24hrs.

Hurley

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
435 AM EDT Sat Jun 1 2024
Day 1
Valid 12Z Sat Jun 01 2024 - 12Z Sun Jun 02 2024

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
FAR SOUTHERN ALABAMA AND SOUTHERN/WESTERN FLORIDA PANHANDLE|...

A potentially high-impact event along the Gulf coast across
southern Alabama and the western Florida will have already started
by the time the Day 1 period begins at 01/12Z. Slow moving showers
and thunderstorms will be capable of training over the same area
with extreme rainfall rates leading to flash flooding, with some
concerns for locally significant impacts. Storms that formed prior
to 01/12Z taped a moisture rich atmosphere along a ribbon of
instability to produce a 1 hour rainfall rate in excess of 3 inches
according to MRMS radar estimates. Between rainfall rates that are
expected to exceed 2 or 3 inches...confluent flow of deep moisture
off the Gulf of Mexico and am environment supportive of back-
building and training...increasing areal coverage of impactful
flash flooding has prompted an upgrade to Moderate Risk,

Elsewhere...there is a Slight risk of excessive rainfall extending
g north and east of the activity along the Gulf as a shortwave lift
northward from the the Lower Mississippi Valley over a region made
more hydrologically sensitive by heavy rainfall earlier in the
past 3 to 7 days. Rainfall amounts and rates should be tapering off
with time as low level flow becomes less supportive with time so
maintained a broad apron of Marginal.

The risk for excessive rainfall will redevelop across portions of
the western high plains as another round of late day convection
develops near the dry line that propagates out towards the central
plains. Introduced a Slight Risk over parts of Kansas southward to
the Texas Panhandle where there is the best overlap for areal
average rainfall amounts of an inch or so...with some places having
had convection traverse the region over the past couple of days.

Bann

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
435 AM EDT Sat Jun 1 2024
Day 2
Valid 12Z Sun Jun 02 2024 - 12Z Mon Jun 03 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE CENTRAL AND NORTHERN PLAINS ON SUNDAY...

The focus for an excessive rainfall threat shifts into the northern
and central plains on Sunday and Sunday night as a low amplitude
trough makes its way out of the northern Rockies and tracks towards
the western Great Lakes. Moisture transport into the region will
be aided by strengthening low level flow over the plains which taps
deeper moisture...with enough pooling ahead of an approaching cold
front to boost precipitable water values into the 1.6 to 1.8 inch
range by 03/00Z. The lift resulting from the mid level wave and the
formation of 80 to 100 kt jet streak near the international border
supporting initial development that spreads south into an
increasingly unstable airmass with higher precipitable water values
by Sunday evening.

Maintained the Marginal risk area across the coastal regions of
Washington and Oregon. 00Z numerical guidance shows a period of 12
hours or so with prolonged and sustained moisture transport from
the eastern North Pacific Ocean directed normal to the coastal and
Cascade ranges. IVT values peak in the 700 to 900 kg per meter per
second range around 03/00Z and then weakens in the early morning
hours on Monday. While atmospheric rivers are normally much of a
consideration in summer...the upper level jet is quite anomalous
with the u-component of the 500 mb flow being greater than 5
standardized anomalies greater than climatology helping boost
precipitable water values to greater than an inch over the western
half of Oregon and southwest Washington by 03/06Z (at or above the
90th percentile for this time of year) with 1.5 inch precipitable
water values along the immediate Oregon coast by Sunday evening.
That all gives support to the NBM and WPC QPF guidance of 1 to 3
inches...with the highest amounts in the west aspect of the Coastal
Ranges and the Cascade Range...by the time that Day 2 ends at
03/12Z.

Bann

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
435 AM EDT Sat Jun 1 2024
Day 3
Valid 12Z Mon Jun 03 2024 - 12Z Tue Jun 04 2024

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN THE CENTRAL US
AND IN THE PACIFIC NORTHWEST|...

Central U.S....
There is a Marginal Risk of excessive rainfall over a broad and
rather unfocused area across the central U.S owing to weak and
difficult to time shortwave energy ejecting out over the Plains
ahead of largely zonal flow that gradually backs as broader height
falls over the Rockies. The atmosphere over the plains will
generally be moist enough to support locally heavy rainfall from
any storms that form...but confidence was below average as to the
placement and timing of the forcing.

In the West...
There is a Marginal Risk of excessive rainfall over
portions of the northern Intermountain region as zonal flow draws
deeper moisture inland that interacts with the terrain in the
northern Intermountain region (especially parts of the Bitterroots
and Sawtooth ranges). The resulting QPF is generally expected to be
in the 1 to 1.5 inch range where the flow impacts the
terrain...with spaghetti plots suggesting a low end chance for 2
inch totals. At the same time...weak shortwave ridging along the
Washington/Oregon coast will lead to a decreasing risk of excessive
rainfall as rainfall rates decrease and areal coverage diminishes
with time.

Bann

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EDT Sat Jun 1 2024


A vigorous shortwave and frontal system (anchored by southern
Canada low pressure) reaching the Dakotas into the Upper Midwest on
Tuesday will provide forcing and a focus for rain and
thunderstorms as instability abounds ahead of it. Smaller scale
shortwaves farther south should also track eastward and promote
scattered convection. A Marginal Risk is in place for the Day
4/Tuesday ERO for much of the Mississippi Valley and expanded a bit
into the Mid-South based on recent model trends. Some locations
within this area will be sensitive due to rainfall from prior days.
The best focus for widespread moderate to heavy rain is likely
across the Upper Midwest, but uncertainty in amounts and placement
as well as the effects of the rainfall precludes a Slight Risk
issuance at this time. Into Wednesday, convection is forecast to
shift east ahead of the cold front into the Great Lakes region and
Ohio and Tennessee Valleys, and a Marginal Risk is delineated for
those areas. For both days, the forward motion of the storms may be
a limiting factor for flooding to become too concerning. Steady
progression of the front will take rain chances into the East for
Thursday-Friday, with possible focus of heavier amounts from the
northern Mid-Atlantic into the interior Northeast where the best
forcing is.

Some lingering precipitation is forecast in the Northwest on
Tuesday before drying out midweek with the amplifying ridge aloft.
Gusty winds are possible in the northern Rockies behind the strong
southern Canada/northern tier U.S. surface low on Tuesday. Into
late week, some return flow of moisture is possible across the
southern/central Rockies and Plains, but with considerable
uncertainty in coverage and amounts of rain. The same can be said
of possible precipitation affecting the Northwest late week.

Next week will remain hot across South Texas westward through the
Rio Grande Valley, where the combination of hot temperatures into
the 90s and 100s as well as humidity will keep heat indices in the
upper 100s, locally 110+. Temperatures nearing or exceeding 100F
may stretch across the southern High Plains through Tuesday but
should moderate somewhat by midweek behind a frontal passage. Some
above normal temperatures are possible across the northern tier at
times. But the next big concern will be increasing heat across the
West as upper ridging builds in. Highs broadly will run 10-15
degrees above average, with even warmer anomalies of 15-20+ degrees
for the central California valleys and portions of the Great
Basin. Temperatures should reach over 100F across the central
California valleys, and near/over 110F in the Desert Southwest.
Scattered daily record high minimum and maximum temperatures are
possible. Per the Climate Prediction Center, this hot pattern could
continue into early next week.


Tate

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EDT Sat Jun 1 2024


A vigorous shortwave and frontal system (anchored by southern
Canada low pressure) reaching the Dakotas into the Upper Midwest on
Tuesday will provide forcing and a focus for rain and
thunderstorms as instability abounds ahead of it. Smaller scale
shortwaves farther south should also track eastward and promote
scattered convection. A Marginal Risk is in place for the Day
4/Tuesday ERO for much of the Mississippi Valley and expanded a bit
into the Mid-South based on recent model trends. Some locations
within this area will be sensitive due to rainfall from prior days.
The best focus for widespread moderate to heavy rain is likely
across the Upper Midwest, but uncertainty in amounts and placement
as well as the effects of the rainfall precludes a Slight Risk
issuance at this time. Into Wednesday, convection is forecast to
shift east ahead of the cold front into the Great Lakes region and
Ohio and Tennessee Valleys, and a Marginal Risk is delineated for
those areas. For both days, the forward motion of the storms may be
a limiting factor for flooding to become too concerning. Steady
progression of the front will take rain chances into the East for
Thursday-Friday, with possible focus of heavier amounts from the
northern Mid-Atlantic into the interior Northeast where the best
forcing is.

Some lingering precipitation is forecast in the Northwest on
Tuesday before drying out midweek with the amplifying ridge aloft.
Gusty winds are possible in the northern Rockies behind the strong
southern Canada/northern tier U.S. surface low on Tuesday. Into
late week, some return flow of moisture is possible across the
southern/central Rockies and Plains, but with considerable
uncertainty in coverage and amounts of rain. The same can be said
of possible precipitation affecting the Northwest late week.

Next week will remain hot across South Texas westward through the
Rio Grande Valley, where the combination of hot temperatures into
the 90s and 100s as well as humidity will keep heat indices in the
upper 100s, locally 110+. Temperatures nearing or exceeding 100F
may stretch across the southern High Plains through Tuesday but
should moderate somewhat by midweek behind a frontal passage. Some
above normal temperatures are possible across the northern tier at
times. But the next big concern will be increasing heat across the
West as upper ridging builds in. Highs broadly will run 10-15
degrees above average, with even warmer anomalies of 15-20+ degrees
for the central California valleys and portions of the Great
Basin. Temperatures should reach over 100F across the central
California valleys, and near/over 110F in the Desert Southwest.
Scattered daily record high minimum and maximum temperatures are
possible. Per the Climate Prediction Center, this hot pattern could
continue into early next week.


Tate

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
1031 AM EDT Mon May 13 2024

Valid 00Z Tue May 14 2024 - 00Z Fri May 17 2024

...WPC Winter Weather Desk no longer routinely staffed this
summer...

Pending any significant winter weather, the WPC Winter Weather Desk
will not be staffed this summer. The desk will resume continuous
staffing starting in late September 2024.

Most of the winter products from WPC will continue to be produced,
including the Winter Storm Severity Index (WSSI), Probabilistic
Winter Storm Severity Index (WSSI-P), and the Probabilistic Winter
Precipitation Forecasts (PWPF).

WPC

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 AM EDT Sat Jun 1 2024

Valid 12Z Tue Jun 04 2024 - 12Z Sat Jun 08 2024

...Excessive heat likely to continue over southern Texas, while
heat builds in the West for the latter half of next week...


...Overview...

As the medium range period begins Tuesday, expect an upper-level
shortwave to track across the north-central U.S. along with a
surface low pressure/frontal system, spreading rain and
thunderstorms to much of the Mississippi Valley. This shortwave
trough will meet a somewhat blocky pattern farther east and
slow/deepen over the east-central U.S. late week into the weekend,
with rain chances gradually shifting toward the eastern U.S. along
and ahead of the cold front. Meanwhile an upper ridge atop Mexico
and southern Texas Tuesday will expand to affect much of the
western U.S. midweek and beyond, producing potentially hazardous
heat. Then an upper trough may approach the West Coast late week
but with uncertain timing.


...Guidance/Predictability Assessment...

Recent model guidance is more agreeable than it was a day ago
regarding the timing of the shortwave tracking near the
U.S./Canadian border Tuesday-Wednesday. This feature is likely to
form a closed upper low by Thursday near to northwest of the Upper
Great Lakes. Deterministic and AI models are more variable with the
placement of the upper low and the southern extent of the
resultant trough. The newer 00Z GFS/CMC end up reaching farther
south with the trough than the previous 12/18Z cycle, but the 00Z
ECMWF elongates the upper low west-east strangely by next Saturday.
Thus the details are still in question by late week/weekend with
this feature.

The relatively better agreement with the north-central to eastern
U.S. trough also yields better model consensus regarding the
western U.S. ridge, but uncertainties remain on the ridge's
periphery. The evolution of the eastern trough/low will affect the
ridge's extent north, with the greatest differences of ridging vs.
troughing arising in the north-central U.S. by Friday-Saturday.
Southern stream energy and possible closed upper low west of Mexico
through much of the period could play a role in the ridge's shape
on the southwest side. Then, there is model spread with timing of
troughing in the eastern Pacific approaching the Northwest late
week. The ECMWF is showing ridging strongly holding on in the
Northwest with the Pacific trough well west all the way through
Saturday, but EC-based AI/ML models indicate the trough farther
east. However, the GFS runs are well on the eastern side of the
envelope. A middle ground more like the ensemble means seemed best
for timing of that approaching troughing.

The WPC forecast utilized a multi-model deterministic blend early
in the forecast period given good agreement in the large scale
pattern at least. As the period progressed, transitioned to a blend
incorporating the GEFS/EC ensemble means to half Day 6 and more
Day 7, given the increasing spread and uncertainty.


...Weather/Hazards Highlights...

A vigorous shortwave and frontal system (anchored by southern
Canada low pressure) reaching the Dakotas into the Upper Midwest on
Tuesday will provide forcing and a focus for rain and
thunderstorms as instability abounds ahead of it. Smaller scale
shortwaves farther south should also track eastward and promote
scattered convection. A Marginal Risk is in place for the Day
4/Tuesday ERO for much of the Mississippi Valley and expanded a bit
into the Mid-South based on recent model trends. Some locations
within this area will be sensitive due to rainfall from prior days.
The best focus for widespread moderate to heavy rain is likely
across the Upper Midwest, but uncertainty in amounts and placement
as well as the effects of the rainfall precludes a Slight Risk
issuance at this time. Into Wednesday, convection is forecast to
shift east ahead of the cold front into the Great Lakes region and
Ohio and Tennessee Valleys, and a Marginal Risk is delineated for
those areas. For both days, the forward motion of the storms may be
a limiting factor for flooding to become too concerning. Steady
progression of the front will take rain chances into the East for
Thursday-Friday, with possible focus of heavier amounts from the
northern Mid-Atlantic into the interior Northeast where the best
forcing is.

Some lingering precipitation is forecast in the Northwest on
Tuesday before drying out midweek with the amplifying ridge aloft.
Gusty winds are possible in the northern Rockies behind the strong
southern Canada/northern tier U.S. surface low on Tuesday. Into
late week, some return flow of moisture is possible across the
southern/central Rockies and Plains, but with considerable
uncertainty in coverage and amounts of rain. The same can be said
of possible precipitation affecting the Northwest late week.

Next week will remain hot across South Texas westward through the
Rio Grande Valley, where the combination of hot temperatures into
the 90s and 100s as well as humidity will keep heat indices in the
upper 100s, locally 110+. Temperatures nearing or exceeding 100F
may stretch across the southern High Plains through Tuesday but
should moderate somewhat by midweek behind a frontal passage. Some
above normal temperatures are possible across the northern tier at
times. But the next big concern will be increasing heat across the
West as upper ridging builds in. Highs broadly will run 10-15
degrees above average, with even warmer anomalies of 15-20+ degrees
for the central California valleys and portions of the Great
Basin. Temperatures should reach over 100F across the central
California valleys, and near/over 110F in the Desert Southwest.
Scattered daily record high minimum and maximum temperatures are
possible. Per the Climate Prediction Center, this hot pattern could
continue into early next week.


Tate


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