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

…Flash flooding possible in the Ohio/Tennessee Valleys and
central/southern Appalachians through early this week…

…Scattered severe thunderstorms forecast across portions of the Northern
Plains Monday and Upper Midwest Tuesday…

…Dangerous mid-summer heat wave to begin expanding across the central
U.S. on Monday…

Bouts of thunderstorms are expected to continue over portions of the
Ohio/Tennessee Valleys and spread further into the central/southern
Appalachians to start off the work week. An active upper-level pattern
featuring at least a couple shortwaves and an approaching surface frontal
system from the west will help to focus storm development over the
Ohio/Tennessee Valleys and eventually into the southern Appalachians
Monday. Plentiful moisture in place will also continue to lead to the
threat of heavier rain rates, with increasing storm coverage into the
evening and potential back building/repeated rounds of storms raising the
chance for locally heavy rainfall totals. As such, a Slight Risk of
Excessive Rainfall (level 2/4) is in place for the threat of some
scattered flash flooding. In addition, sufficient instability/shear will
be in place over the Ohio Valley for a couple more intense storms, as well
as the threat for a more organized storm complex later Monday evening. The
Storm Prediction Center has included a Slight Risk (level 2/5) for severe
weather as well mainly for the threat of damaging winds. A similar pattern
will be in place on Tuesday, with the focus shifting further into the
southern and central Appalachians as the upper-level energy and surface
frontal system move eastward. Another Slight Risk of Exessive Rainfall is
in effect here for additional instances of flash flooding. Outside of the
flash flooding threat, scattered thunderstorms with moderate to locally
heavy rainfall are expected more broadly over the Midwest/Southeast
Monday, and also over portions of New England as a coastal low approaches.
Rain chances will expand over the Mid-Atlantic/Northeast as the system
approaches from the west on Tuesday. Forecast high temperatures across the
East will vary depending on cloud/storm coverage, with mostly mid-80s to
low 90s expected.

Some additional storms will be possible further west along the frontal
boundary into the Upper Midwest and Northern Plains. Embedded upper-level
energy will help to trigger one round of storms over the Northern Plains
on Monday. Stronger upper-level flow will lead to more deep-layer shear
here than further east, with another Slight Risk of severe weather for the
threat of some very large hail as well as significant damaging winds if
storms consolidate/grow upscale into an organized system later in the
evening. Another round of severe weather is possible downstream over the
Upper Midwest Tuesday as yet another upper-level impulse helps to trigger
storms along the frontal boundary. Very high moisture will lead to strong
to extreme instability, with a Slight Risk in place for the chance of more
damaging winds.

Outside of the severe weather threat, heat will become the big story more
broadly over the central U.S. over the next few days as an upper-level
high strengthens/expands over the region. Forecast high temperatures
Monday and Tuesday are expected to soar into the low to mid-100s over the
Central Plains, with upper-90s to low 100s to the west over much of the
High Plains, and mid- to upper 90s for the Middle and Lower Mississippi
Valley. High humidity values over the Mississippi Valley and eastern
portions of the plains will lead to heat indices in the 105-110 degree
range, potentially as high as 115 for some locations, with widespread
heat-related warnings/advisories in place. Warm morning lows only dropping
into the mid- to upper 70s will provide little relief from the heat
overnight. This combination of hotter temperatures to the west, higher
heat indices to the east, and the multi-day duration of this heat wave
will increase the danger not only to more sensitive groups, but also the
general public, particularly those without adequate air conditioning.

A stagnant troughing pattern over the West will keep temperatures mostly
below average across the region, especially over portions of the Pacific
Northwest and northern Great Basin/Rockies. Forecast highs Monday-Tuesday
range between the 60s and 70s along the Pacific Coast, the 70s and 80s in
the Pacific Northwest and northern Great Basin/Rockies, the 80s and 90s
for interior California and the central Great Basin/Four Corners Region,
and 100s in the Desert Southwest. A cold front passing through the Pacific
Northwest will bring some rain chances on Monday, spreading into the
northern Rockies Tuesday. Smoke from area wildfires will also continue to
plague parts of the West, particularly over portions of the northern Great
Basin, resulting in poor air quality and areas of reduced visibility.

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

…Flash flooding possible in the Ohio/Tennessee Valleys Sunday, spreading
into the central/southern Appalachians by Monday…

…Severe thunderstorms expected across portions of the Northern/Central
Plains with flash flooding into the Upper Midwest Sunday…

…Cooler than normal for much of the West with monsoonal thunderstorms
for portions of the Southwest…

A lingering frontal boundary snaking through the Ohio/Tennessee Valleys
deeper into the Southeast and off the Atlantic coast will continue to help
trigger scattered showers and thunderstorms over the next couple of days.
An upper-level wave passing over the Ohio/Tennessee Valleys will provide a
focus for more numerous storms on Sunday, possibly into the
central/southern Appalachians as well, with very moist, southerly Gulf
flow leading to some locally heavy downpours. A Slight Risk of Excessive
Rainfall (level 2/4) is in effect for the threat of some scattered
instances of flash flooding, particularly where storms may have the
tendency to backbuild/repeat over areas in vicinity of the frontal
boundary. Then, as the upper-level wave continues east on Monday, the
focus for storms will spread further into the central/southern
Appalachians, with another Slight Risk of Excessive Rainfall in effect for
additional instances of flash flooding. High temperatures broadly across
the Ohio Valley into the Southeast and along the Gulf Coast will remain at
or a bit below average given widespread clouds and storms, with highs
generally in the mid-80s to low 90s.

A frontal system passing slowly through the Northern/Central Plains and
the Upper Midwest will bring storm chances to these regions Sunday.
Plentiful moisture, instability, and strong upper-level flow overhead
leading to sufficient deep-layer shear is expected to result in some more
intense, organized storms. Initially isolated storms/supercells over
portions of South Dakota, central Nebraska, and northwestern Kansas may
produce some large hail and damaging winds. Eventual upscale growth into
an organized convective system Sunday evening may bring a damaging wind
threat downstream into southwestern Minnesota and northwestern Iowa. The
Storm Prediction Center has highlighted these areas with a Slight Risk
(level 2/5) of severe weather. The expanding coverage of storms heading
eastward, as well as plentiful moisture to lead to heavy rainfall rates,
will also bring the threat of flash flooding into Iowa. Additional storms
will continue ahead of the front over Minnesota through early morning
Sunday, with another round of storms expected Sunday night. Repeated
storms bringing heavy rainfall on top of already wet antecedent conditions
will lead to the risk of some scattered flash flooding here as well. A
Slight Risk of Excessive Rainfall extends from portions of Minnesota
southward into Iowa to cover these threats. The system will continue into
the Great Lakes region Monday, bringing showers and storms with moderate
to locally heavy rainfall. High temperatures ahead of the front will be
rather hot, running 10-15 degrees above average for some locations, with
80s to near 90 in the Upper Midwest and 90s to low 100s southwestward into
the Central Plains and southern High Plains. A few near
record-tying/breaking highs will be possible in the southern High Plains
Monday.

An upper-trough over the West will keep temperatures below average for
most of the region. Forecast highs Sunday-Monday range between the 60s and
70s along the Pacific Coast; 70s and 80s in the Pacific Northwest; 80s and
90s in the Great Basin, Four Corners Region, and interior California; and
the 100s into the Desert Southwest. Some Monsoonal storms will continue
over parts of the Southwest, particularly southeastern
Arizona/southwestern New Mexico, with an isolated threat of flash
flooding. A storm system approaching the Pacific Northwest will bring some
shower chances here as well. Smoke from wildfires will also continue to
plague parts of the West, particularly over the northern Great
Basin/Rockies, resulting in poor air quality and areas of reduced
visibility. Elsewhere, conditions will be trending hotter across most of
the Northeast, with 80s and low 90s forecast. A coastal low approaching
southern New England is looking more likely to bring cooler temperatures
and some rain chances over the next couple of days.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri Jul 26 2024
Valid 12Z Fri Jul 26 2024 – 12Z Sun Jul 28 2024

…Scattered showers and thunderstorms continue across much of the South
with a risk for flash flooding Friday in the coastal Carolinas and
southeastern Texas…

…Storm chances for portions of the Upper Midwest and Northern Plains
heading into the weekend with severe weather possible Saturday…

…Monsoonal thunderstorms continue for portions of the Intermountain West
with isolated flash flooding possible…

Scattered showers and thunderstorms will continue across much of the South
along and ahead of a cold front slowly pushing southward through the
region. Plentiful moisture will bring the threat of some locally heavy
downpours. A couple upper-level waves, one over the Carolinas and another
to the west over the Southern Plains, will help to provide a focus for
some locally more widespread, intense downpours along the coastal
Carolinas and southeastern Texas. Wet antecedent conditions from rainfall
the past few days will increase the risk for some scattered flash
flooding, with Slight Risks of Excessive Rainfall (level 2/4) in place. An
isolated threat for flash flooding will exist more broadly across the
region both Friday and Saturday. The presence of storms and general
cloudiness will help to keep temperatures near or below Summer-time
averages, especially over portions of eastern and central Texas, with
highs generally in the 80s.

A frontal boundary draped across the Upper Midwest/Northern Plains will be
the focus for daily thunderstorm chances heading into the weekend. More
widely scattered storms are expected Friday before a passing upper-level
shortwave helps to encourage more widespread storms on Saturday.
Sufficient instability along with the arrival of stronger winds aloft
bringing increasing deep-layer shear is expected to result in at least a
few more intense thunderstorms. The Storm Prediction Center has issued a
Slight Risk of severe weather (level 2/5) for portions of northwestern
Minnesota and eastern North Dakota for the threat of some large hail as
well as damaging winds, particularly if storms can organize into a
convective system into the evening hours. High temperatures will remain
rather hot across the Northern/Central Plains and Upper Midwest, with
highs in the 90s upwards of 10-15 degrees above average.

Monsoonal showers will continue across portions of the Intermountain West
Friday and Saturday, particularly from the Southwest north through the
Rockies and central Great Basin. Deep moisture lingering through the area
will bring the threat for some locally intense downpours. Isolated
instances of flash flooding will remain possible, particularly for terrain
sensitive areas such as burn scars. Forecast highs across the West will
generally be below average with an upper-level trough overhead, with highs
in the 80s and 90s across the Pacific Northwest, Great Basin, Rockies, and
interior California, and 60s and 70s along the Pacific Coast. The Desert
Southwest will be much hotter, with highs in the low to mid-110s.
Elsewhere, conditions will be mostly dry from the Midwest to the Northeast
under the presence of high pressure. Forecast high temperatures Friday
will be a bit below average, with low to mid-80s forecast. Highs will warm
up a bit on Saturday, reaching into the mid- to upper 80s.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Thu Jul 25 2024
Valid 12Z Thu Jul 25 2024 – 12Z Sat Jul 27 2024

…Another day of major to locally extreme Heat Risk across the northern
High Plains before cooler air arrives behind a cold front…

…Excessive Rainfall is forecast for the Texas coast through tonight with
more scattered showers and thunderstorms across the southern tier states
to the East Coast…

…Monsoonal thunderstorms continue across the Great Basin and into the
Four Corners region with threats of localized flash flooding while fire
weather danger emerges over the interior Northwest…

A slow-to-evolve summertime weather pattern will continue across much of
the U.S. mainland while a more progressive Pacific cold front sweeps
across the northwestern part of the country through the next couple of
days. Under this weather pattern, unsettled weather and relatively cool
temperatures for July will continue across the South as well as the Great
Lakes. The stronger forcing associated with the Pacific front will push
the heat dome into the northern High Plains today behind a warm front,
resulting in another day of major to locally extreme Heat Risk for the
region. High temperatures will once again reach well up into the 100s with
little to no rainfall expected. Meanwhile, the heat will continue to
become less intense over the Central Valley of California and the Desert
Southwest. Some of the hot air over the northern Plains will be pushed
into the upper Midwest by the weekend with highs reaching into the 80s and
90s. Please continue to practice heat safety before cooler air arrives
behind the cold front.

The Pacific cold front currently making its way through the northern
Rockies into the High Plains will gradually become nearly stationary
through the next couple of days. Lightning associated with dry
thunderstorms triggered by the passage of the cold front will raise fire
danger concerns over the interior northwestern U.S. into the northern High
Plains. Farther south, monsoonal thunderstorms across the Great Basin
today will shift farther eastward into the Four Corners and as far north
as Wyoming through the next couple of days.

In contrast to the heat in the West, cooler than normal temperatures will
prevail across the mid-section of the country and portions of the eastern
U.S. where a stalled front will keep plenty of clouds along with scattered
thunderstorms. It appears that coastal sections of Texas will see the
highest chance of receiving heavy rainfall today into tonight as some
influx of tropical moisture from the Gulf of Mexico could interact with
the weak front under a broad upper-level southwesterly flow ahead of a
trough. A moderate risk of excessive rainfall remains in place from the
mid and upper Texas coast to southwestern Louisiana through tonight.
Thunderstorms across other areas of the southern tier states are not
expected to be severe, but they could result in localized flooding issues
from time to time. The same is true along the East Coast with a slight
risk of excessive rainfall over portions of the Carolinas through Friday
night where storms are expected to be more numerous. Meanwhile, showers
and a few embedded thunderstorms today across New England will clear out
by Friday as a low pressure wave moves away into eastern Canada.