Atmospheric Rivers

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Wed Jun 05 2024
Valid 12Z Wed Jun 05 2024 – 12Z Fri Jun 07 2024

…Excessive Heat Warnings in effect across parts of California’s Central
Valley region as well as the Desert Southwest; Extreme Heat Risk continues
across south Texas…

…Thunderstorms and heavy to Excessive Rainfall possible from Southern
Plains to Northeast through Thursday…

A very pronounced ridge will build across the Western U.S. over the next
few days while upper-level lows influence the pattern across the lower 48
from their respective stations off the Baja and Nova Scotia Coasts. The
upper ridge will support a heat wave which will expand across the region.
High temperatures in the 90s and 100s will be 20-30 degrees above average
for this time of year, while low temperatures in the upper 60s and 70s
will offer little respite at night. Widespread high and low temperature
records may be tied or broken through Friday. There are Excessive Heat
Warnings in effect for California’s Central Valley as well as portions of
the Desert Southwest including southeastern California, southern Nevada
and western/southern Arizona. Mild night time temperatures will continue
to plague southern Texas through the end of the week. These extremely hot
conditions will affect anyone without effective cooling and/or adequate
hydration.

A pair of low pressure systems tracking across the eastern half of the
country will trigger scattered to isolated showers and thunderstorms
across much of the region today before shifting into just the East Coast
on Thursday. Deep layer moisture paired with instability will support
locally heavy rainfall over parts of the Ohio Valley, Central Appalachians
and Mid-Atlantic where a Slight Risk (at least 15%) of Excessive Rainfall
leading to Flash Flooding is in effect for today. The threat for Excessive
Rainfall shifts into parts of the interior Northeast and New England on
Thursday, where another Slight Risk of Excessive Rainfall is in effect. A
pattern change will ensue across the Eastern U.S. on Thursday, in which a
digging trough will usher in cooler air temperatures and continue through
the weekend.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Jun 04 2024
Valid 12Z Tue Jun 04 2024 – 12Z Thu Jun 06 2024

…There is a Moderate Risk of Excessive Rainfall leading to Flash
Flooding over parts of southeastern Oklahoma and the ArkLaTex today…

…Severe Thunderstorms possible across parts of the Mississippi Valley
today…

…Growing Excessive Heat potential over portions of California’s central
valley region as well as the Desert Southwest; southern Texas heat risk
persists…

An amplified upper trough will swing through the Great Plains and
Mississippi Valley, bringing with it a pair of cold fronts and
thunderstorm activity over the next couple of days. Potent mid-level
energy on the southern periphery of the trough anchored over
southern-central Canada will move slowly across the Deep South today and
promote a pair of MCSs to propagate across the ArkLaTex region this
morning and then again tonight. The repeating thunderstorms (potentially
severe) over the same area prompted the issuance of a Moderate Risk (at
least 40%) of Excessive Rainfall leading to Flash Flooding over portions
of southeastern Oklahoma through the ArkLaTex for the 24 hour period
ending Wednesday morning. Frontally driven diurnal convection will also
occur across the Upper/Middle Mississippi Valley this afternoon and
evening. The Storm Prediction Center issued Slight Risks (level 2/5) of
Severe Thunderstorms over parts of the Upper/Middle Mississippi Valley and
another one across the ArkLaTex into western Mississippi. Large hail and
severe wind gusts will be the main threat for any severe storms that
develop over the Upper/Middle Mississippi Valley, while damaging wind
gusts will be the sole threat across the ArkLaTex/Lower Mississippi Valley.

A deepening upper ridge in the West and cutoff low west of Baja will
support a heat wave across much of the Western U.S. over the next several
days. Temperatures will be below average for the Pacific Northwest today
but will be overtaken by warmer conditions beginning on Wednesday. Areas
of particular concern include the low elevation regions of California’s
central valley and the Desert Southwest where high temperatures will
easily climb over 100 degrees beginning today. High temperature anomalies
of 20-30 degrees above average are likely. Widespread temperature records
are expected to be tied or broken across much of the aforementioned areas.
Excessive Heat Warnings and Watches extend from the central valley down
through southern California’s deserts, southern Nevada and
southern/western Arizona. HeatRisk will peak over California’s central
valley on Wednesday before expanding into the Desert Southwest later this
week. Little overnight relief will make for dangerous conditions for those
without effective cooling and/or adequate hydration. HeatRisk over
southern Texas peaks today but persists for the next few days.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Jun 03 2024
Valid 12Z Mon Jun 03 2024 – 12Z Wed Jun 05 2024

…Excessive Rainfall and Severe Weather threaten portions of the
Mississippi Valley and Southern Plains today…

…Increasing Excessive Heat Risk potential over parts of the West and
southern Texas through mid-week…

Shortwave energy spinning through the Northwest will support showers and
thunderstorm activity across the region today. Rainfall rates over the
favored terrain of the Cascades and Northern Rockies will be high enough
to warrant an Excessive Rainfall threat. Thus, a Slight Risk (at least
15%) of Excessive Rainfall leading to Flash Flooding is in effect for
portions of the Northern Rockies, while a Marginal Risk (at least 5%) area
is in place over the Cascades, Olympics and Seattle Metro area. Elsewhere,
showers and thunderstorms are expected to continue over parts of the Great
Plains and Mississippi Valley today. Pockets of severe thunderstorms
capable of producing heavy to excessive rainfall may develop over parts of
the Southern Plains into the Mississippi Valley. Slight Risks of Excessive
Rainfall and Severe Thunderstorms are in effect over those areas, where a
swath of damaging wind gusts are possible. The severe thunderstorm threat
concentrates over parts of the Central Plains and Middle Mississippi
Valley on Tuesday, where a Slight Risk is in effect. Large hail is
possible at the outset when storms are more cellular, but will then be
followed by a congealing of cells into a line of storms with damaging wind
gusts eventually being the main threat.

An upper ridge is expected to develop over the West early to mid-week.
High temperatures will gradually climb into 100s by Wednesday and Thursday
with many records potentially being tied or broken on those days.
Excessive Heat Warnings are in effect for the central valley region of
California while Excessive Heat Watches are in effect for parts of the
Desert Southwest. Extreme HeatRisk is probable to continue for much of
southern Texas through Wednesday. This level of heat risk means that there
will likely be little to no overnight relief for those without effective
cooling and/or adequate hydration.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sun Jun 02 2024
Valid 12Z Sun Jun 02 2024 – 12Z Tue Jun 04 2024

…Excessive Rainfall and Severe Thunderstorms possible over portions of
the Great Plains and Mississippi Valley…

…Heavy to Excessive Rainfall possible across parts of the Northwest
through Monday…

…Increasing Excessive Heat threat over parts of California, Nevada and
Arizona…

A series of shortwaves will be responsible for Excessive Rainfall and
Severe Thunderstorms that develop across the Great Plains and Mississippi
Valley over the next few days. Today, showers and isolated thunderstorms
will spread from the High Plains into the Mississippi Valley. Some storms
may turn severe. The Storm Prediction Center issued an Enhanced Risk
(level 3/5) of Severe Thunderstorms across portions of the Central High
Plains this afternoon and evening. Very large hail, severe wind gusts
greater than 75 mph, and a few tornadoes are expected. Rain rates in some
of those storms could be high enough to cause flash flooding which is why
there’s a Slight Risk (at least 15%) of Excessive Rainfall over parts of
the Northern/Central Plains and Upper/Middle Mississippi Valley.

Elsewhere, a deep upper low will transport anomalous tropical Pacific
moisture into the Northwest today. Excessive Rainfall is naturally a
concern over the favorable terrain of the Cascades, Bitterrroots, Salmon
River Mountains as well as the Seattle metro, where Slight Risks (at least
15%) are in effect through Monday. Monday will be a Marginal Risk kind of
day for Excessive Rainfall and Severe Thunderstorms over parts of the
Southern/Central Plains and Mississippi Valley. Cloudy/cooler conditions
will prevail over the Northwest thanks to the Atmospheric River event set
to unfold over the next couple of days. Otherwise, the Great Plains and
Northeast are likely to experience above average temperatures this week.
Abnormal heat is expected to expand across parts of the West mid-week.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
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.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri May 31 2024
Valid 12Z Fri May 31 2024 – 12Z Sun Jun 02 2024

…Severe Weather and Excessive Rainfall potential across mid-section of
the country this weekend…

…Heat Risk continues over far southern Texas…

Southern stream shortwave energy will be the catalyst for severe
thunderstorm and excessive rainfall potential across parts of the Central
U.S. this weekend. Today a complex of thunderstorms will propagate from
the Central/Southern High Plains across northern and eastern Texas,
followed by another round of storms which will develop and move into parts
of Arkansas and southern Missouri this evening. The Storm Prediction
Center issued a Slight Risk (level 2/5) of Severe Thunderstorms for these
events with wind damage and an isolated tornado being the main hazard
threats. Isolated large hail and severe wind gusts will be possible over
the Central High Plains. There’s also a Slight Risk (at least 15%) of
Excessive Rainfall leading to Flash Flooding over portions of the
Middle/Lower Mississippi Valley and eastern Oklahoma/Texas. There’s still
plenty of uncertainty as to where exactly storms will initiate and be most
impactful.

The focus for showers and thunderstorms shifts into the Lower Mississippi
and Ohio Valleys on Saturday. Another complex of storms may propagate into
the central Gulf Coast beginning in the morning. Some of these storms may
be efficient enough rain producers to warrant another Slight Risk of
Excessive Rainfall over much of Mississippi and Alabama. The Storm
Prediction Center has another Slight Risk of Severe Thunderstorms along
the Central to Southern High Plains where supercells capable of producing
severe wind, hail and a couple of brief tornadoes could impact the region
Saturday afternoon.

Elsewhere, heat risk continues to be a concern over south Texas through
the weekend. Convection over the Central U.S. will lead to below average
high temperatures today. Troughing in the West will support above average
temperatures across much of the region this weekend. A deep upper-level
low will arrive over the Pacific Northwest on Sunday, bringing with it the
potential for heavy rainfall

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Wed May 29 2024
Valid 12Z Wed May 29 2024 – 12Z Fri May 31 2024

…Active central U.S. weather pattern to continue, with heavy rains,
flash flooding, and severe weather possible…

…Anomalous heat continues across far southern Texas and Florida, while
hot temperatures begin to build in the Southwest and interior California
Valleys…

The active and stormy weather pattern impacting the central U.S. is set to
continue over the next few days while also expanding in coverage to
include much of the Great Plains, middle and lower Mississippi Valley. For
today, a cold front progressing across the Northern Rockies and central
Great Basin in response to a Northwest upper trough will help spark
numerous thunderstorms into the northern Plains and parts of the central
High Plains. A few scattered storms could contain intense rainfall rates,
hail, and damaging winds. Scattered thunderstorms are also possible along
a lingering stationary front extending along the Gulf Coast and southern
Plains, which have greater chances of producing instances of flash
flooding due to thunderstorms overlapping with saturated ground
conditions. As upper troughing enters the Great Plains on Thursday, even
more rounds of slow-moving tumultuous thunderstorm clusters are
anticipated. This leads to a broad region at risk for hail, damaging
winds, and flash flooding from Kansas and eastern Colorado to
north-central Texas. This activity is then forecast to gradually slide
eastward on Friday to impact the ArkLaTex region, as well as extending
into the mid-Mississippi Valley and southern Plains once again. Flash
flooding will remain a concern due to the relatively slow-moving nature of
thunderstorms occurring within a moisture rich environment. Widespread
areal-averaged rainfall totals by the end of the week are forecast to add
up to over 2 inches throughout much of Kansas, Oklahoma, northern Texas,
southern Arkansas, and northern Louisiana, with localized amounts over 4
inches possible.

Simmering heat is expected to continue for much of the central and
southern Florida Peninsula as highs reach into the mid-90s, which may
tied/break daily record highs today. Highs also returning to the upper 90s
are forecast along the Rio Grande Valley of southern Texas after early
morning thunderstorms. However, a larger area of hot weather will begin to
build throughout the Southwest and interior California valleys by the end
of the week. Afternoon temperatures into the upper 90s and triple digits
can be expected.

Elsewhere, high pressure stretching from the Great Lakes to the Southeast
will keep most areas east of the Mississippi River dry with the exception
of the Ohio Valley, Mid-Atlantic, and Northeast today. A compact storm
system will be swinging eastward over the Mid-Atlantic and produce
scattered showers and thunderstorms. The main weather hazards associated
with these storms are forecast to be associated with lighting and locally
heavy rain.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue May 28 2024
Valid 12Z Tue May 28 2024 – 12Z Thu May 30 2024

…Numerous strong to severe thunderstorms and areas of flash flooding
likely across portions of northern and central Texas today…

…Unsettled weather with thunderstorms and heavy rain possible over the
northern Great Basin/Rockies today before shifting into the northern High
Plains on Wednesday…

…Sweltering heat continues across parts of South Texas and southern
Florida…

The Lone Star State will be the focus for active weather today as strong
thunderstorms develop along a southern High Plains dryline and lingering
stationary front. Ample atmospheric moisture content and instability will
support the likelihood of storms containing significant damaging wind
gusts and very large hail. Ongoing thunderstorms along the Red River
Valley of the South are expected to continue through the morning hours
before numerous additional storms form across western and north-central
Texas by the afternoon. Merging cells and clusters of storms are also
likely to contain intense rainfall rates capable of triggering several
flash floods, particularly for areas just west of Dallas-Fort Worth and
north of Austin. The threat of scattered flash flooding and severe
thunderstorms includes a much larger region extending from the Texas
Panhandle to the western Gulf Coast. For the overnight timeframe, heavy
rain and severe weather chances are forecast to gradually decrease and
slide eastward within Texas. Residents and visitors are reminded to remain
weather aware, have numerous ways to receive warnings and never drive
across flooded roadways.

A cold front progressing across the Northwest, northern Great Basin, and
northern Rockies today will provide enough forcing to produce the
potential for scattered severe thunderstorms capable of containing
damaging wind gusts for parts of northeast Oregon, northern/central Idaho,
and western Montana. A few storms may also produce heavy rain and isolated
flash flooding. This area of unsettled weather is expected to swing
eastward by midweek and enter the north-central High Plains before an
expanding area of storminess returns to the central/southern Plains on
Thursday.

Elsewhere, cold air advection on the southwestern periphery of an eastern
Canada low pressure system will produce scattered areas of showers and
storms over the next few days from the Great Lakes and Upper Midwest to
the Ohio Valley, Mid-Atlantic, and Northeast. A few storms could contain
hail and brief damaging winds today from southern Wisconsin to northern
Illinois and northwest Indiana.

The heat plaguing much of the Gulf Coast and southern Texas is finally
abating, but will linger across parts of southern Texas today with heat
indices up to 115 degrees. High temperatures are also expected to remain
above average and near daily record highs throughout the central and
southern Florida Peninsula over the next few days.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon May 27 2024
Valid 12Z Mon May 27 2024 – 12Z Wed May 29 2024

…Severe thunderstorms and areas of heavy rain to impact much of the
eastern U.S., with isolated severe weather possible in the southern
Plains…

…Dangerous heat remains in place this Memorial Day throughout
southern/central Texas, the western and central Gulf Coast, as well as
southern Florida before some gradual relief by midweek…

…Unsettled weather and thunderstorms return to the southern Plains on
Tuesday, as well as the northern Great Basin and northern Rockies…

The severe weather threat shifts eastward today along a cold front
extending southward from a low pressure system forecast to slide northeast
over the Great Lakes. Ongoing storms stretching from the upper Ohio Valley
to the lower Mississippi Valley are expected to weaken this morning, but
redevelopment is likely this afternoon along and ahead of this boundary.
Clusters of merging thunderstorms are possible in the Mid-Atlantic and
Northeast, which may also contain intense rainfall rates. This heavy rain
could lead to scattered instances of flash flooding from northeast
Maryland to the Catskill Mountains of New York, where a Slight Risk (level
2/4) of Excessive Rainfall is in effect through tonight. The severe
weather threat includes a broader region extending from the lower Great
Lakes to the Southeast, with damaging wind gusts and hail the primary
hazards, with isolated tornadoes possible in the eastern Mid-Atlantic. As
the cold front extends westward towards the southern Plains, a few
isolated severe thunderstorms are also possible in parts of central and
eastern Texas.

South of the cold front in parts of Texas, the Gulf Coast, and southern
Florida, oppressive and dangerous heat continues today. Highs into the
upper 90s and triple digits are forecast throughout much of the Lone Star
State, with a few daily record highs possible. Elevated humidity levels
will lead to heat indices up to 120 degrees across portions of southern
Texas. Excessive Heat Warnings and Heat Advisories are in effect from
south-central Texas to the central Gulf Coast. Additionally, a simmering
Memorial Day is also in store for parts of the Florida Peninsula, where
daily record highs could be tied/broken in Key West, Port St Lucie, and
Melbourne. Summer heat is expected to linger over the Sunshine state
through midweek, while gradual cooling enters the Gulf Coast and Texas as
an approaching cold front inches towards the region. Residents are
reminded to follow proper heat safety and check on the vulnerable
population over at least the next few days.

The next round of active weather should return to the southern Plains on
Tuesday as scattered thunderstorms impact parts of southeast New Mexico
and much of Texas near a lingering stationary front. Severe wind gusts and
large hail are possible, as well as heavy rain producing scattered areas
of flash flooding. Meanwhile, a separate area of thunderstorms is possible
along a cold front as it progresses from the northern Great Basin on
Tuesday into the northern High Plains on Wednesday. Isolated thunderstorms
could turn severe and contain intense rainfall rates in these regions.