28-Day Weather Outlook

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Thu Sep 12 2024
Valid 12Z Thu Sep 12 2024 – 12Z Sat Sep 14 2024

…Heavy rainfall from Francine will spread into the Mid-South, Tennessee
Valley, and Southeast today while the severe weather threat shifts east
into Alabama and the Florida Panhandle…

…A round of moderate to heavy rain and strong thunderstorms with move
across the northern High Plains with high-elevation snow in the northern
Rockies…

…Elevated to critical fire weather concerns extend across much of the
High Plains and into portions of the central Great Basin…

Tropical Storm Francine continues to weaken and lift north early this
morning into southern Mississippi at the same time spreading gusty winds
and heavy rain across the region. The system is forecast to lose remaining
tropical characteristics later today as it pushes northward into the
Mid-South and connects with nearby frontal boundaries, while still
producing areas of locally heavy rain and chances for severe
thunderstorms. Tornadoes will be the main severe weather hazard through
tonight, potentially impacting parts of Alabama and the Florida Panhandle
along a slow-moving warm front. The Storm Prediction Center has issued a
Slight Risk (level 2/5) of severe weather for this region. The greatest
threat for considerable flash flooding exists across parts of northern and
central Alabama, where a slow-moving line of showers and thunderstorms
capable of containing intense rainfall rates could linger for several
hours and produce localized totals up to 10 inches. Heavy rain is also
possible from northeast Arkansas through the Tennessee Valley and into the
Florida Panhandle today. Looking ahead to the start of the weekend,
showers and localized torrential downpours will remain possible throughout
much of the Southeast as lingering tropical moisture and stationary
frontal boundaries stay draped across the region. Residents are advised to
have multiple ways of receiving warnings and never drive across flooded
roadways.

A potent storm system is also impacting parts of the West and High Plains
as an area of low pressure organizes in eastern Montana today. Areas of
heavy rain and severe weather are possible across the state. Gusty winds
and large hail associated with thunderstorms are most likely to impact
eastern Montana and far western North Dakota through tonight, with heavy
rain a potential weather hazard in central/western Montana. Additionally,
cool temperatures in the high elevations of the northern Rockies could
lead to early-season mountain snowfall for western Montana and the greater
Yellowstone National Park area. The other aspect of this system will
correspond with strong southerly winds throughout the High Plains. Wind
gusts up to 50 mph are possible, which could result in a few power
outages. These strong winds will also increase the fire weather threat
across the region as dry vegetation and low relative humidity create a
ripe environment for erratic fire behavior. Red Flag Warnings and/or Wind
Advisories span from southern Utah to North Dakota.

Elsewhere, high pressure will keep much of the Great Lakes and Northeast
dry as high temperatures increased into the 80s through the beginning of
this weekend. Warm and dry weather will also be found throughout the
Desert Southwest and southern Plains, with high temperatures into the
mid-to-upper 90s. Conversely, below average temperatures in the wake of a
cold front will be felt across much of the West to end the week.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Wed Sep 11 2024
Valid 12Z Wed Sep 11 2024 – 12Z Fri Sep 13 2024

…Hurricane Francine is forecast to make landfall in Louisiana later this
evening with damaging winds, life-threatening storm surge, and torrential
rainfall…

…A round of moderate to heavy rain with high-elevation snow forecast
throughout the northern Rockies…

…Elevated to critical fire weather concerns across much of the Great
Basin and portions of the High Plains…

Ample attention is on the central Gulf Coast today as Hurricane Francine
is anticipated to make landfall in Louisiana this evening before spreading
impacts north to the Mid-South through the end of the week. Once the storm
pushes onshore south-central Louisiana tonight, life-threatening weather
conditions are expected to impact parts of the state, including the cites
of Lafayette, Baton Rouge, and New Orleans. Hazardous weather conditions
include storm surge, strong winds, torrential rainfall, and a few
tornadoes. While the strongest winds and peak storm surge are expected to
occur closer to the center of Francine in south-central portions of
Louisiana, the heavy rain and tornado threats are forecast to span much
farther east along the central and eastern Gulf Coast, including southern
Mississippi, Alabama, and the Florida Panhandle. In total, Francine is
expected to produce rainfall amounts of 4 to 8 inches, with local amounts
to 12 inches for the central/eastern Gulf Coast through Thursday night.
This rainfall could lead to considerable flash and urban flooding. As
Francine pushes northward into the Mid-South and weakens by the end of the
week, additional heavy rain is possible and could lead to scattered
instances of flash flooding. Additionally, a lingering frontal boundary
draped across the Florida Peninsula could lead to localized flash flooding
concerns over the next few days. Residents under hurricane-related
warnings should follow advice of local officials, including evacuation
orders, and never drive across flooded roadways.

A separate weather system will also impact the Nation through the end of
this week, with moderate to heavy rain and gusty winds impacting parts of
the Intermountain West and northern Rockies. This autumn storm will be
driven by a deep upper low crossing from the Northwest today before
closing-off and churning over the northern Rockies on Thursday. Most of
the impactful precipitation will be confined to the northern Rockies and
the High Plains on Montana. A few inches of rainfall could produce
flooding concerns throughout northwest Montana, prompting a Slight Risk
(level 2/4) of Excessive Rainfall both today and Thursday. Snow levels
dropping to around 7,000-8000 feet may also create hazardous winter-like
conditions for the high elevations of Montana Idaho, and northwest
Wyoming. The other aspect of this system will be associated with gusty
winds and increased fire weather concerns throughout the Great Basin and
High Plains. Strong winds combined with dry vegetation and low relative
humidity are forecast to be more pronounced over the Great Basin today and
increase the chances for erratic fire behavior. Additionally, elevated to
critical fire weather also exists across the High Plains and is most
apparent on Thursday as southerly winds increase in speed. Red Flag
Warnings and Fire Weather Watches have been issued throughout 10 states
between California and Nebraska. Outdoor burning is not recommended
throughout these regions and residents are reminded to not go near any
wildfires as they can spread quickly.

Otherwise, a large high pressure system over the Northeast will aid in
producing tranquil weather from the Great Lakes to much of the East. Well
above average temperatures are expected to overspread the north-central
U.S. before a warming trend is also noticeable across the southern Plains
by Friday. Highs across the northern Plains, Upper Midwest, and Great
Lakes are forecast to reach into the upper 80s and low 90s, while upper
90s eventually return to the western half of Texas and eastern New Mexico.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Sep 10 2024
Valid 12Z Tue Sep 10 2024 – 12Z Thu Sep 12 2024

…Life-threatening storm surge and hurricane-force winds, as well as the
risk of considerable flash flooding are forecast across southern Louisiana
on Wednesday as Francine approaches…

…Heavy rain expected to impact parts of the northern Rockies by
midweek…

…Elevated to critical fire weather concerns across much of the
Intermountain West…

As of early this morning Tropical Storm Francine continues churning in the
western Gulf of Mexico just to the southeast of Brownsville, Texas and
moving on a gradual northward motion. Francine is forecast to strengthen
into a hurricane before an expected landfall in southern Louisiana on
Wednesday. As the system approaches the central Gulf Coast and eventually
pushes inland across Louisiana, an increased threat of life-threatening
storm surge, hurricane-fore winds, and considerable flash flooding is
anticipated. Rainfall amounts of 4 to 8 inches, with local amounts up to
12 inches are forecast across much of central/eastern Louisiana and
Mississippi through Thursday night. Francine is then forecast to continue
its trek northward into the Mid-South on Thursday, while quickly
weakening. However, additional heavy rainfall and flash flooding concerns
are possible into western Tennessee neighboring regions. A stationary
front extending eastward from the center of the storm over the next few
days will also focus areas of numerous, slow-moving thunderstorms capable
of containing intense rainfall rates between the Florida Peninsula and
central Gulf Coast. Residents are reminded to remain weather-ready and
never drive across flooded roadways.

The only other section of the Lower 48 expecting chances for heavy rain
through midweek are parts the northern Rockies as a deep upper-level low
crosses over the region. A few inches of rainfall throughout northwest
Montana could lead to an increased risk of flash flooding on Wednesday,
which has prompted a Slight Risk (level 2/4) of Excessive Rainfall. This
storm system will also produce gusty winds throughout the Intermountain
West and lead to fire weather concerns. Specifically, the Storm Prediction
Center has issued a Critical Fire Weather area for much of Nevada and
western Utah. Current and continued wildfire activity over the Great Basin
will further add to the smokey skies noticeable throughout the northern
Plains, Midwest, and parts of the Ohio/Tennessee valleys.

High temperatures will remain above average average and into potentially
dangerous levels across parts of southern California and the Southwest
today before a quick cooldown commences by midweek. Meanwhile, upper
ridging in the north-central U.S. is expected to produce more summer-like
afternoon temperatures into the upper 80s and low 90s as far north as the
northern Plains and Upper Midwest by Thursday. These temperatures equate
to around 10 to 20 degrees above average, but are not expected to break
many daily records.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Sep 09 2024
Valid 12Z Mon Sep 09 2024 – 12Z Wed Sep 11 2024

…Heavy rain and a risk of flash flooding expected throughout much of the
Gulf Coast and Florida Peninsula into midweek…

…Potentially dangerous heat forecast across southern California and the
Southwest today…

…Elevated to critical fire weather concerns as well as Air Quality
Alerts remain across much of the Great Basin…

A stationary front extending from the Florida Peninsula through the
northern Gulf of Mexico along with a gradually organizing area of low
pressure in the southwest Gulf of Mexico (labeled Potential Tropical
Cyclone Six by the National Hurricane Center) will continue to produce
areas of heavy rain and the risk of flash flooding through midweek. For
today, the heaviest rainfall is anticipated over portions of southern
Texas, the central Gulf Coast, and much of the Florida Peninsula, mainly
associated with scattered showers and thunderstorms near the stationary
boundary. This may lead to isolated flash flooding concerns mainly
concentrated to urban locations. By Tuesday and more pronounced on
Wednesday, increased moisture content and organized bands of thunderstorms
associated with Potential Tropical Cyclone Six are forecast to reach the
western and central Gulf Coast. This will increase the risk of heavy
rainfall and considerable flash flooding. At the moment, the greatest risk
for rainfall amounts up to 12 inches and numerous flash floods are
forecast throughout southern Louisiana. Life-threatening storm surge and
damaging winds are also possible from the Upper Texas Coast to the
Louisiana coastline as the system is forecast to reach hurricane strength
in the northwest Gulf of Mexico by midweek. Residents should ensure they
have their hurricane plan in place and check www.nhc.noaa.gov for the
latest forecast.

Dangerous heat is in the forecast for at least one additional day for
southern California and parts of the Southwest. Highs into the upper 90s
and triple digits have prompted Excessive Heat Warnings and Heat
Advisories to be issued, with a cooling trend set to commence by midweek.
The combination of above average temperatures, dry vegetation, and gusty
winds have resulted in elevated to critical fire weather concerns
throughout much of the Intermountain West through the next couple of days.
Additionally, current wildfires continue to pump smoke into the atmosphere
of the northern Great Basin, leading to poor air quality. This smoke is
also forecast to extend eastward in the mid-to-upper levels of the
atmosphere through the northern Plains and Ohio Valley, creating
noticeably hazy skies.

Elsewhere, well above average temperatures are expected across the
north-central U.S. as highs return to the upper 80s and low 90s, which
equates to around 10-15 degrees above average. Cooler, fall-like
temperatures will kickoff the new workweek throughout the Ohio Valley and
East until temperatures return to near normal by Wednesday as the dominant
high pressure system in place slowly slides eastward to the western
Atlantic.

While notable precipiation should be mostly sparse across the Lower 48
outside of the Gulf Coast, a few areas of locally heavy rain are possible
across the Northeast and Northwest through Wednesday. Isolated severe
thunderstorms are possible throughout Upstate New York today as a weak
cold front dives across the region, with some storms potentially
containing damaging wind gusts. Increasing precipitation chances are also
forecast to spread into the Northwest and Northern Rockies as a deep upper
low swings eastward from the northeast Pacific.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sun Sep 08 2024
Valid 12Z Sun Sep 08 2024 – 12Z Tue Sep 10 2024

…Dangerous heat continues to impact portions of southern California and
the Southwest through Monday…

…Heavy rain and scattered instances of flash flooding remain possible
along the Gulf Coast and parts of the Southeast over the next several
days…

…Below average temperatures forecast across much of the Midwest and East
through the beginning of the week…

Potentially dangerous and record-breaking heat is forecast to continue
across southern California as highs soar into the upper 90s and triple
digits away from the immediate coastline. Excessive Heat Warnings remain
in effect through Monday as a gradual cooldown commences on Tuesday. Highs
into the triple digits are also forecast throughout the remainder of the
Desert Southwest, but not considered as anomalous as values forecast
across southern California. Elsewhere, above average temperatures are
anticipated across the northern Great Basin and northern Plains as
upper-level ridging slides eastward. Heat will wane across eastern
Washington and neighboring states by Tuesday as the core of the
late-summer temperatures concentrate over the northern Plains. Highs in
the north-central U.S. are forecast to reach into the low-to-mid 90s early
this week, which equates to around 10 to 20 degrees above average for this
time of year. Additionally, sultry heat and humidity will impact southern
Florida once again today, where Heat Advisories have been issued due to
maximum heat indices forecast to near 110 degrees. Remember to follow
proper heat safety by staying hydrated, limiting strenuous outdoor
activity during peak daytime heating, and checking on vulnerable
individuals.

Much of the Nation is anticipated to be void of notable precipitation over
the next few days, with the Gulf Coast and parts of the Southeast being
the lone exception. A lingering stationary front and developing area of
low pressure in the western Gulf of Mexico will focus heavy rainfall
potential from the coastal Carolinas to the Florida Peninsula and entire
Gulf Coast region. Scattered flash flooding is possible where the heaviest
rainfall occurs, with urban and low-lying areas most at risk to flooding
impacts. Otherwise, isolated flash flooding is also possible in parts of
the Intermountain West through early this week due to widely scattered
thunderstorms developing in tandem with daytime heating.

Large surface high pressure extending from the southern Plains to the
Midwest and East throughout Tuesday will not only supply sunny and dry
conditions for much of the Lower 48, but well below average temperatures
as well. In fact, daily record lows are possible between the Midwest and
Mid-Atlantic this morning as temperatures dip into the 40s for most
locations. Patchy frost is possible in low lying protected areas. As this
autumnal airmass moderates somewhat early this week, afternoon
temperatures will gradually warm back into the mid-80s by Tuesday.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sat Sep 07 2024
Valid 12Z Sat Sep 07 2024 – 12Z Mon Sep 09 2024

…Dangerous heat continues to impact portions of the West this weekend…

…Heavy rain and scattered instances of flash flooding are possible along
the Gulf Coast and parts of the Southeast…

…Below average temperatures to settle in across much of the Midwest and
East through the beginning of next week…

A few more days of record-breaking and dangerous heat are in store for
parts of the West as well above average temperatures linger underneath a
weakening upper-level high pressure system. Areas most likely to
experience major to extreme HeatRisk (levels of heat that affect anyone
without effective cooling or adequate hydration) through Sunday include
southern California, the Desert Southwest, and the northern Great Basin.
These regions are also where Excessive Heat Warnings and Heat Advisories
remain in effect. High temperatures in the Southwest are expected to soar
into the upper 90s and triple digits, with 110s in the typically hottest
desert locations through at least Monday. Highs into the upper 90s are
forecast to simmer the northern Great Basin before a gradual cooling trend
commences by early next week, with the anomalously warm temperatures
forecast to shift eastward into the northern Plains. Residents and
visitors are advised to continue following proper heat safety. This
includes staying hydrated and avoiding extended periods of time outdoors
during the hottest parts of the day. Poor air quality will also remain a
concern for parts of the Great Basin as wildfire smoke continues to
overspread the region.

A stationary front extending from off the Southeast coastline to the
northern Gulf of Mexico will continue to provide a focus for numerous
showers and thunderstorms over the next few days as its moisture gradient
gets reinforced by a separate approaching cold front sinking southward
across the Deep South today. Areas of locally heavy rain and scattered
flash floods are possible from the coastal Carolinas to the central Gulf
Coast, including northern and central Florida. Greater concentration of
tropical downpours are anticipated to reorient to southern Texas by Monday
as an area of low pressure develops in the Bay of Campeche and ushers
elevated atmospheric moisture westward to the western Gulf Coast.

Elsewhere, a cold front sweeping across the East Coast today will produce
scattered showers and thunderstorms throughout the Northeast. Behind this
frontal boundary and underneath potent high pressure, below average and
crisp temperatures are expected to overspread much of the Great Lakes,
Midwest, and East this weekend. Widespread lows into the 40s will lead to
a few chilly mornings, with several daily record lows possible between
Missouri and New Jersey on Sunday. Patchy frost cannot be ruled out for
some locations. Conversely, southern Florida will remain hot and humid
this weekend as high temperatures rise into the low-to-mid 90s, while heat
indices approach 110 degrees.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri Sep 06 2024
Valid 12Z Fri Sep 06 2024 – 12Z Sun Sep 08 2024

…Dangerous heat continues to impact large sections of the West into this
weekend…

…Heavy rain and instances of flash flooding are likely throughout the
central Gulf Coast and Southeast over the next few days…

…Showers and isolated severe thunderstorms possible from the Ohio Valley
to the Lower Great Lakes today…

An upper level high pressure system is expected to continue aiding well
above average and potentially dangerous temperatures throughout the West
into the first full weekend of September. Highs today are forecast to soar
into the triple digits for much of the Southwest and interior California,
with 110s in the typically hottest locations of the Desert Southwest.
Meanwhile, daily high temperature records are possible in the Northwest
where mid-to-upper 90s are in the forecast. A minimal relaxing of the
extreme heat should be felt throughout much of the West and Southwest on
Saturday, but with temperatures remaining above average. The core of the
anomalous heat will shift to the northern Great Basin and northern Rockies
as parts of eastern Oregon and Washington experience another day with
highs well into the 90s. Poor air quality will also remain an issue
throughout parts of the northern Great Basin as wildfire smoke continues
to plague the region. Residents and visors are advised to follow proper
heat safety, which includes checking on vulnerable individuals.

Not much heavy precipitation to speak of throughout the Nation over the
next few days besides along the Gulf Coast and parts of the Southeast. A
lingering stationary front and a couple waves of low pressure will provide
a focus for tropical downpours over already saturated soils. The greatest
threat for heavy rainfall turning into flash flooding impacts are forecast
across southeast Louisiana today, where a Moderate Risk (level 3/4) of
Excessive Rainfall has been issued. Several inches of rain occurring
within a very short period of time could lead to numerous flash floods
here. A scattered flash flood threat also extends eastward along and just
north of the stationary front into northern Florida and southern Georgia.
This frontal boundary is expected to gradually sink southward by Saturday
as an area of low pressure exits off the Southeast coastline, with a
persisting isolated flash flood potential extending from the central Gulf
Coast and northern Florida to the coastal Carolinas. Remember, most flood
fatalities occur within vehicles… turn around, don’t drown.

Elsewhere, a cold front sweeping across the Ohio Valley and Lower Great
Lakes will usher in below average temperatures throughout the Great Lakes,
Midwest, before reaching the East Coast by this weekend, while also
producing areas of showers and thunderstorms. A few storms could produce
locally gusty winds and hail today in the Ohio Valley and nearby Lake Erie
region. Scattered showers are expected to progress eastward along the cold
front on Saturday and dampen weekend plans throughout the Interior
Northeast and sections of New England by Saturday evening.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Thu Sep 05 2024
Valid 12Z Thu Sep 05 2024 – 12Z Sat Sep 07 2024

…Very heavy rain and the threat for scattered to numerous instances of
flash flooding continues for the Gulf Coast states the next couple of
days…

…Dangerous heat wave intensifies over the Southwest and West Coast…

Heavy rain and flash flooding remain in the forecast along the Gulf Coast
as a stationary front and coastal low drive multiple days of widespread
showers and thunderstorms across the region. The elongated area of low
pressure and front from the north-central to western Gulf will keep the
greatest focus for repeated rounds of storms moving onshore over the
central Gulf Coast and upper Texas Gulf Coast today (Thursday),
potentially spreading a bit further northward into the Lower Mississippi
Valley. Very moist Gulf air continues to contribute to very efficient
downpours with these storms, approaching 2-3″ per hour in some cases,
exacerbating the threat for heavy totals and flash flooding. There is now
a Moderate Risk (level 3/4) of Excessive Rainfall for southeastern
Louisiana where prior days rainfall has lead to very wet antecedent
conditions and brings a locally greater threat for scattered to numerous
instances of flash flooding, especially for the urban areas around greater
New Orleans. A broader Slight Risk (level 2/4) is in place across the
region for additional scattered instances of flash flooding. An
approaching upper-level wave will help to shift the focus for heavy
rainfall a bit eastward on Friday as the front begins to meander away from
the western Gulf and lift northward into southern Georgia, leading to
decreasing rain chances further West. Another Slight Risk of Excessive
Rainfall extends from the central Gulf Coast eastward through the Florida
Panhandle into southern Georgia where a similar threat for intense heavy
downpours with repeated rounds of storms will lead to several inches of
rain, and the potential for scattered instances of flash flooding.
Temperatures will remain well below average across the region north of the
frontal boundary and in the presence of widespread rain and cloud cover
with mostly upper 70s and low 80s. Some locations may only reach into the
low 70s Friday. On the other hand, it will be hot south of the front
across the Florida Peninsula, with highs in the low 90s. A Heat Advisory
is in place for South Florida where the combination of heat and humidity
will lead to heat indices in the 105-110 degree range.

A dangerous heat wave will intensify over the Southwest and West Coast the
next couple of days with a strong upper-level ridge now settled over the
region. Forecast high temperatures Thursday and Friday range from the 110s
for the Desert Southwest, low 100s to near 110 for southern California,
mid-100s for the central California Valleys, and the 90s to low 100s for
central/northern California and into the Pacific Northwest. Several
record-tying/breaking highs are possible across the Pacific Northwest.
Widespread heat-related warnings and advisories are in place given the
heightened threat for heat-related illness to anyone without efficient air
conditioning or adequate hydration. While not quite as hot, highs will be
well above average and potentially uncomfortable even for some immediate
coastal locations with temperatures reaching into the 80s.

Elsewhere, a broad area of showers and thunderstorms is expected ahead of
a pair of cold fronts passing through the Upper Midwest/Great Lakes,
Central Plains, and central/southern High Plains and adjacent Rockies. The
greatest chance for some moderate to locally heavy rainfall will be under
the influence of an upper-level trough over the Upper Midwest/Great Lakes,
and where upslope flow enhances storms over the southern Rockies. A few
isolated instances of flash flooding will be possible in the southern
Rockies given recent rains and some more sensitive burn scars. Storm
chances with moderate to locally heavy rainfall will continue ahead of the
front as it pushes eastward through the Great Lakes overnight Thursday and
into the Lower Great Lakes/Upper Ohio Valley on Friday. Some storms may
begin to spread into the Northeast and Mid-Atlantic by early Saturday
morning. Temperature-wise, the passing cold front will bring well below
average, Fall-like temperatures to the Northern Plains and Upper Midwest
Thursday, with highs in the 60s to low 70s. Temperatures will be rather
chilly for the Upper Great Lakes by Friday as highs drop into the 50s.
Conditions will be much warmer ahead of the front Thursday over the
Midwest and Ohio Valley with highs in the mid-80s to low 90s. The
approaching front will bring temperatures down into the 70s for portions
of the Midwest Friday. Mild conditions will continue for much of the East
Coast through Friday with highs in the upper 70s to low 80s.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Wed Sep 04 2024
Valid 12Z Wed Sep 04 2024 – 12Z Fri Sep 06 2024

…Heat wave builds over the Southwest and the West Coast this week…

…Heavy rain and flash flood potential continues for the Gulf Coast
states the next couple of days…

An upper-level ridge building northward over the West Coast will help to
expand and intensify a heat wave over the region through the next few
days. Forecast highs today (Wednesday) range from the upper 100s to
mid-110s in the Desert Southwest, the mid-90s to low 100s for southern and
central California, and the mid-90s to low 100s for portions of the
Pacific Northwest. Temperatures soar even higher on Thursday, with highs
into the 110s for the Desert Southwest, the 100s to near 110 in southern
California, the mid-100s for the central California Valleys, and the low
100s for portions of the Pacific Northwest. Widespread heat-related
warnings and advisories are in place as the threat for heat-related
illness and impacts will increase today and especially on Thursday. This
heat will be dangerous to anyone without effective air conditioning or
sufficient hydration. While not quite as hot, temperatures will also be
well above average along the immediate Pacific Coast, with highs into the
80s for many locations.

Heavy rain and the threat for flash flooding will remain in the forecast
for the Gulf Coast states this week as a stationary front and coastal low
drive multiple days of widespread showers and thunderstorms across the
region. The placement of the elongated area of low pressure in the western
Gulf will keep the focus for the most widespread rainfall over portions of
the central and upper Texas Gulf Coasts, and possibly a bit further north
into the Lower Mississippi Valley. Extremely moist Gulf air will lead to
very heavy downpours (upwards of 2-3″ per hours rates) with continued
rounds of storms moving onshore. Forecast areal average rainfall totals
are in the 3-5″ range, with locally higher amounts of 7″+ possible, most
likely near the immediate coast. A Slight Risk of Excessive Rainfall
(level 2/4) is in place for the region both today and tomorrow given the
threat for scattered instances of flash flooding. Storms will also
increase along the southeastern Atlantic Coast today and Thursday, and
daily thunderstorm chances will continue for the Florida Peninsula. The
passage of the frontal boundary to the coast and widespread storms and
clouds will keep temperatures down across Texas and the Southeast the next
couple of days, with highs generally in the 80s. Conditions will be hotter
south of the boundary in Florida with temperatures into the 90s. A Heat
Advisory is in place for South Florida today as the combination of highs
into the 90s and high humidity will lead to heat indices in the 105-110
degree range.

Elsewhere, much of the eastern U.S. outside of the the South will be dry
with generally mild temperatures. Early Fall-like highs in the 70s are
expected throughout New England, the Mid-Atlantic, and Carolinas through
Thursday. An upper-level ridge passing over the Midwest will bring
temperatures back up into the mid- to upper 80s over the next couple of
days. An approaching upper-level trough/surface frontal system will bring
shower and thunderstorm chances to portions of the Central/Northern Plains
and Upper Midwest today, with the greatest storm coverage and chance for
some more moderate rainfall in the Upper Midwest and the central High
Plains/adjacent Rockies. The frontal system will push further
southeastward on Thursday, bringing storm chances to the Great Lakes,
Central Plains, and central/southern High Plains/adjacent Rockies. Once
again, the greatest storm coverage and heavier rainfall will be focused to
the north over the Great Lakes and to the southwest over the
central/southern High Plains and adjacent Rockies. Some isolated flash
flooding will be possible over the southern Rockies given more sensitive
soils from recent rainfall and over any burn scars.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Sep 03 2024
Valid 12Z Tue Sep 03 2024 – 12Z Thu Sep 05 2024

…Areas of heavy rain and the potential for flash flooding continue in
Texas and along the Gulf Coast the next couple of days…

…One more day of late-Summer heat for the north-central U.S. Tuesday
before focus shifts to a building heat wave in the West Wednesday…

Thunderstorms capable of producing heavy rainfall will persist across
portions of Texas and along the Gulf and southeastern Atlantic Coasts this
week as very moist Gulf air pools around a quasi-stationary frontal
boundary lingering through the region. A passing upper-level disturbance
will lead to more widespread storms once again today (Tuesday) over
portions of central Texas where a locally greater threat for some flash
flooding will exist, with a Slight Risk of Excessive Rainfall (level 2/4)
outlooked for the region. Further east along the central Texas Gulf Coast,
very moist, onshore flow aided by a stubborn coastal low and continued
rounds of storms moving inland will bring further heavy downpours that
could lead to several inches of rainfall. A Slight Risk of Excessive
Rainfall has been included here as well as wet antecedent conditions from
rainfall over the past few days will increase the threat for some
additional instances of flash flooding in the area. The upper-level
disturbance will lift northeastward on Wednesday, increasing storm
coverage over the central Gulf Coast and possibly north into the Lower
Mississippi Valley. Another Slight Risk of Excessive Rainfall is in place
given the threat for heavy downpours and scattered flash flooding. Storms
will also increase along the southeastern Atlantic Coast by Wednesday, and
daily thunderstorm chances will continue for the Florida Peninsula.

Further north, an upper-level trough and associated surface cold front
will bring showers and thunderstorms to the northern Rockies today. Some
locally heavy downpours will be possible with an isolated threat of flash
flooding over central Idaho and southwestern Montana. Ahead of this
system, an upper-level ridge over the northern/central High Plains will
lead to another day of well above average, hot late-Summer temperatures,
particularly over the northern High Plains. Forecast highs are into the
90s, with some upper 90s possible for the western Dakotas. The approaching
system from the west will help to bring temperatures back down to average
Wednesday, with highs in the low to mid-80s. Showers and storms are
expected with the passage of the system, particularly over the central
High Plains. Storms chances will also spread into the Upper Midwest as the
system continues east Wednesday night.

Attention in the mid- to late week will turn to a building heatwave over
the West. A strong ridge will settle in over the West Coast following the
passage of the upper-trough over the northern tier, with highs on Tuesday
already beginning to climb into the upper-90s and low 100s over interior
California and 100s to 110s in the Desert Southwest. Then, on Wednesday,
temperatures will soar into the low 100s over interior California and into
the 90s in the Pacific Northwest. While not as hot, much above average
temperatures are expected for coastal areas too, with highs into the low
80s for some locations. Heat-related warnings and advisories have been
issued for the Desert Southwest and central/southern California outside of
the immediate coast given a heightened risk for heat-related illness,
especially for those without access to effective air conditioning.
Elsewhere, most of the eastern U.S. outside of the the South will be dry
with generally mild temperatures. Early Fall-like highs in the 70s are
expected throughout New England, the Mid-Atlantic, and Carolinas.