Atmospheric Rivers

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Sep 17 2024
Valid 12Z Tue Sep 17 2024 – 12Z Thu Sep 19 2024

…A coastal low will bring a threat of flash flooding to the Mid-Atlantic
today…

…A strong low pressure system will bring unsettled weather to the
Rockies and Plains with severe thunderstorms in the northern and central
High Plains…

A coastal low, previously labeled as Potential Tropical Cyclone Eight,
will continue to slowly move north across the Carolinas towards the
Mid-Atlantic over the next day or so. Moist, onshore flow will support
persistent showers and thunderstorms across portions of North Carolina and
the southern Mid-Atlantic today, and locally heavy rainfall could result
in isolated to scattered instances of flash flooding. Flood Watches are in
effect today for portions of southeastern Virginia and North Carolina.
Precipitation coverage and intensity should decrease on Wednesday,
resulting in a lower threat for flash flooding. Coastal flooding will also
be a concern with a prolonged period of onshore winds along the
Mid-Atlantic coast. By Thursday, this system will begin to shift offshore
into the Atlantic and high pressure will build behind it.

Meanwhile, a strong low pressure system will move across the Intermountain
West this morning and is expected to emerge in the northern Plains,
strengthening in the lee of the Rockies later today. Strong, gusty winds
and widespread showers and thunderstorms are forecast with this system in
the vicinity of the low pressure center and along and ahead of the
trailing cold front. Some thunderstorms may become severe this afternoon
and evening in the northern and central High Plains, and the Storm
Prediction Center has highlighted this area with a Slight Risk of severe
thunderstorms (level 2/5) with an embedded Enhanced Risk (level 3/5) over
the central High Plains. Severe storm hazards will include damaging winds
and isolated large hail.

The low pressure center of this system will be nearly stationary over
Montana through Wednesday as it’s forward motion is blocked by high
pressure to the east. This will likely result in heavy rainfall totals
that could cause scattered instances of flash flooding in portions of
Montana. The trailing cold front will slowly push east across the Plains
on Wednesday and Thursday, gradually losing steam, and the threat for
severe weather will decrease.

Another low pressure system will move south along the West Coast Wednesday
and Thursday, which will bring another round of unsettled weather.
Precipitation will spread from the Northwest to the Great Basin and
Southwest by Thursday, mainly falling as rain, but some wintry
precipitation will be possible in the higher elevations.

Initially, temperatures will be well below normal in the West and
Mid-Atlantic and well above normal in the Central U.S. and Northeast, but
temperature anomalies will gradually moderate as we move through the rest
of the week.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Sep 16 2024
Valid 12Z Mon Sep 16 2024 – 12Z Wed Sep 18 2024

…Potential Tropical Cyclone Eight will bring wind and heavy rain to the
Carolinas and Mid-Atlantic…

…A strong upper low will bring unsettled weather and well below normal
temperatures to the West with high elevation snow in the Sierra Nevada and
Intermountain West…

…Severe thunderstorms possible for the Northern and Central High Plains
Tuesday…

While Francine’s remnants have been dissipating over the Southeast,
Potential Tropical Cyclone Eight has been strengthening off the Southeast
Coast. This disturbance is forecast to bring gusty winds and heavy rain to
portions of the Carolinas and Mid-Atlantic and dangerous coastal and beach
conditions to much of the Southeast and Mid-Atlantic coasts. The forward
motion of Potential Tropical Cyclone Eight will be slowed down by strong
high pressure over the Northeast, which will increase the chance of heavy
rainfall totals in the Carolinas today. Flash flooding will be a concern,
especially in the eastern Carolinas where the highest rainfall totals are
forecast, and flooding could have locally significant impacts. This
disturbance is forecast to gradually move north across the Carolinas into
the Mid-Atlantic, bringing a threat of locally heavy rainfall to the
region mid-week.

In the West, a deep upper low will bring unsettled weather and well below
normal temperatures to the region this week. The upper low is accompanied
by a strong surface frontal system that will push east across the
Intermountain West today and into the Plains Tuesday afternoon. This
system will bring widespread precipitation chances and gusty winds to much
of the West. Precipitation will fall mainly in the form of showers and
thunderstorms, but temperatures will be cold enough for the high
elevations of the Sierra Nevada and Intermountain West to see some early
season snow. Winter Weather Advisories are in effect through this evening
for the Sierra Nevada above 8000 feet where up to 4 inches of snow may
fall, and Wind Advisories are in effect through this evening for portions
of the Southwest where wind gusts could exceed 45 mph.

The surface low pressure system is forecast to strengthen in the lee of
the Rockies over Wyoming and Montana, and will bring a threat of scattered
severe thunderstorms to the northern and central High Plains Tuesday
afternoon and evening. The Storm Prediction Center has highlighted these
areas with a Slight Risk of Severe Thunderstorms (level 2/5), and the main
storm hazards will be severe wind gusts and hail. Showers and
thunderstorms will push east across the Plains Tuesday night and move
towards the Mississippi Valley on Wednesday.

Temperatures will have a broad range across the United States over the
next few days. The deep upper low will result in well below normal
temperatures in the West through at least mid-week, with the coldest
anomalies over the Great Basin and California where high temperatures will
be as low as 15-25 degrees below normal. On the flip side, temperatures
will be well above normal in the Central U.S. and Northeast. High
temperatures will generally be in the 80s and 90s for these regions. Below
normal temperatures are also forecast for the Southeast and Mid-Atlantic
today and Tuesday due to expected precipitation and cloud cover, but
temperatures should return to near normal for these regions by Wednesday.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sun Sep 15 2024
Valid 12Z Sun Sep 15 2024 – 12Z Tue Sep 17 2024

…Heavy rain/flash flood threat continues today for portions of the Lower
Mississippi Valley and Southeast…

…A coastal storm will bring wind and rain to the Carolinas and
Mid-Atlantic over the next few days…

…A strong low pressure system will bring unsettled weather and well
below normal temperatures to the West with high-elevation snow in the
Sierra Nevada…

Francine’s remnants will linger over the southeastern U.S. early this week
as a nearly stationary frontal boundary sags south to the Gulf Coast.
Chances for locally heavy rain and isolated to scattered instances of
flash flooding will continue today for portions of the Lower Mississippi
Valley and Southeast. There is a Slight Risk of Excessive Rainfall (level
2/4) for parts of Mississippi, Alabama, and the Florida panhandle where
flooding will be most likely. Chances for showers and storms will persist
across this region over the next few days, but the risk of flooding will
gradually decrease, with only isolated flooding concerns expected Monday
and Tuesday.

Meanwhile, a separate area of low pressure will strengthen off the
Southeast Coast and gradually move north towards the Carolinas. This
system is likely to bring gusty winds, heavy rain, coastal flooding, and
dangerous beach conditions to the Carolinas and portions of the
Mid-Atlantic through mid-week. Strong high pressure over the Northeast
will slow the forward motion of this system, increasing the chance of
heavy rainfall totals and flash flooding. There is a Slight Risk of
Excessive Rainfall (level 2/4) for portions of the eastern Carolinas and
far southeastern Virginia with an embedded Moderate Risk (level 3/4) over
southeastern North Carolina where the risk of flash flooding will be
highest. The National Hurricane Center is also monitoring this system for
potential subtropical or tropical development, and has marked this area
with a 50% chance of tropical formation over the next 48 hours. There is
still quite a bit of uncertainty on the timing, intensity, and track of
this system, so regularly check for forecast updates over the next couple
of days.

In the West, an unsettled pattern is beginning to take root as upper level
troughing moves into the region. A deep upper low will move over the West
Coast today and Monday and push across the Intermountain West to the
Rockies on Tuesday. This will push a strong frontal system across the West
that will bring widespread precipitation chances and much cooler
temperatures to the region over the next few days. Precipitation will
mainly fall as rain, but temperatures will be cold enough in the high
elevations of the Sierra Nevada for some early season snow. A Winter
Weather Advisory is in effect for portions of the Sierra Nevada above 8000
feet where up to 4 inches of snow may fall tonight and Monday.
Precipitation chances will also increase across the Southwest/Four Corners
region today as tropical moisture streams north from Tropical Cyclone
Ileana, which will support monsoon-like showers and thunderstorms through
Tuesday.

Temperatures will have a large range across the United States over the
next few days. Forecast precipitation and cloud cover will keep
temperatures slightly below normal across the Southeast and Mid-Atlantic,
with highs from the mid 70s to the mid 80s. Well above average
temperatures are forecast for the Central U.S. and Northeast, with the
highest anomalies forecast to develop under high pressure in the Upper
Midwest/Great Lakes region. High temperatures will reach the 80s and 90s,
which will be 10-20 degrees above normal for some areas. Well below
average temperatures are forecast to spread across the West through
Tuesday under the deep upper low/trough, and high temperatures will be as
low as 15-25 degrees below normal. The coldest anomalies will be in
Oregon, Nevada, and California on Monday. Highs in the 50s will be common
in the Great Basin, and highs will likely only reach the 30s and 40s in
the Sierra Nevada.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sat Sep 14 2024
Valid 12Z Sat Sep 14 2024 – 12Z Mon Sep 16 2024

…Heavy rain and flash flood threat will continue for portions of the
Southeast this weekend, then the flash flood threat will shift to the
Carolinas/Mid-Atlantic early next week…

…A strong low pressure system will bring unsettled weather to the West
late this weekend/early next week, with wintry precipitation expected at
high elevations…

…Well above average temperatures for the Central U.S. and Northeast;
well below average temperatures for the West…

Though it is now post-tropical, Francine will continue to bring a threat
for heavy rain and flash flooding to portions of the Southeast through
Sunday. The central area of low pressure will gradually sink south towards
the Gulf Coast with a stationary boundary extending to the Southeast Coast
and a cold front extending back towards the Southern Plains. The
stationary boundary will be the main focus for convection this weekend,
and training showers and thunderstorms with locally heavy rainfall will
create a threat for scattered instances of flash flooding. There is a
Slight Risk of Excessive Rainfall (level 2/4) for portions of Arkansas,
Tennessee, Mississippi, Alabama, and Georgia today and Sunday. Flash Flood
Watches are in effect for much of this area, and urban/poor drainage areas
and areas that already received heavy rainfall over the past few days will
be most at risk for flash flooding.

A separate area of low pressure will strengthen along the stationary
boundary extending from the Southeast Coast, which will maintain shower
and thunderstorm chances from Florida to the Carolinas and southern
Mid-Atlantic through early next week. This low pressure system is forecast
to gradually track north along the East Coast early next week and will
bring a heavy rain and flash flood threat to portions of the Carolinas and
Mid-Atlantic. There is a Slight Risk of Excessive Rainfall (level 2/4) for
eastern North Carolina on Monday where scattered instances of flash
flooding will be possible.

In the West, an unsettled pattern is forecast to develop this weekend as a
strong upper low pushes a frontal system across the region. The system
will nudge into the Pacific Northwest today, then move across northern
California, the Great Basin, and the northern Rockies Sunday and Monday.
Widespread showers and thunderstorms will accompany this system, and there
is a broad Marginal Risk of Excessive Rainfall (level 1/4) in effect for
portions of the Northern Rockies and Great Basin on Monday. This system
will also usher in well below normal temperatures, which will allow for
wintry precipitation to fall at higher elevations. A Winter Weather
Advisory is already in effect for portions of the Sierra Nevada where up
to 4 inches of snow may fall Sunday night and Monday. Precipitation
chances will also increase across the Southwest/Four Corners region late
this weekend into early next week as tropical moisture streams north ahead
of Tropical Cyclone Ileana.

Temperatures this weekend will have a large range across the United States
with well above average temperatures in the Central U.S. and Northeast and
well below average temperatures under the strong upper low in the West.
High temperatures will be in the 80s and 90s for the Central U.S. and
Northeast through Monday, which is more than 15 degrees above average for
some areas in the Upper Midwest/Great Lakes. High temperatures in the West
will be near to slightly below average today, then drop to 15 to 25
degrees below average in Oregon, California, and Nevada by Monday. Highs
in the 50s will be common in the Great Basin, and highs will likely only
reach the 30s and 40s in the Sierra Nevada.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri Sep 13 2024
Valid 12Z Fri Sep 13 2024 – 12Z Sun Sep 15 2024

…Francine will continue to weaken while bringing a heavy rain and flash
flood threat to the Southeast over the next couple days…

…Above average temperatures will develop across the Central U.S. and
Northeast while below normal temperatures persist in the Southeast and
West…

Francine will continue to weaken today as its low pressure center meanders
east across northern Arkansas. A stationary boundary extending from the
occluded system will remain parked across the Southeast and provide a
focus for showers and thunderstorms through Saturday. The storm’s slow
motion will result in multiple days of heavy rain for the Southeast, which
will create a flash flooding risk. There is a Slight Risk of Excessive
Rainfall (level 2/4) today from western Tennessee through northern and
central Alabama to central/southern Georgia, with an embedded Moderate
Risk (level 3/4) for portions of northern and central Alabama. Flooding
will be most likely in urban and poor drainage areas and areas that
receive training/repeat convection, and locally considerable flash
flooding may be possible, especially where soils are already saturated
from previous rainfall. The flash flood threat will continue for these
areas on Saturday with another Slight Risk (level 2/4). Flood Watches are
in effect for much of the risk area. If you encounter flooding, turn
around, don’t drown. It is never safe to walk or drive into flood waters,
and most flood fatalities occur in vehicles. Isolated severe thunderstorms
will also be possible for parts of the Southeast today where the Storm
Prediction Center has issues a Marginal Risk of Severe Thunderstorms
(level 1/5). Severe storm hazards may include a few tornadoes or severe
wind gusts.

The flash flood and severe weather threats associated with Francine will
gradually decease through the weekend, and the remnants will begin moving
south Saturday night and stall along the Gulf Coast on Sunday. Another
area of low pressure is forecast to form along the stalled frontal
boundary off the Southeast Coast, which will create stormy weather from
Florida through the eastern Carolinas through this weekend into early next
week.

In the north, an occluded low pressure system north of Montana will push
further into Canada today and Saturday and will bring a weak cold front
across the northern and central Plains. Precipitation will linger on the
backside of the low in the northern Rockies and northern High Plains this
morning, and cold air will allow for snow and mixed wintry precipitation
at higher elevations. Shower and thunderstorm chances will accompany the
weak cold front through Saturday. Strong high pressure over the Northeast
will prevent the front from making significant eastward progress, and the
front will weaken and dissipate on Sunday.

In the West, a stronger Pacific frontal system will approach the coast
later today and move inland over the weekend. Precipitation chances will
begin in the Northwest late tonight/early Saturday and spread across the
Great Basin and northern California Sunday into Monday. Precipitation
chances will also increase across portions of the Southwest on Sunday as
tropical moisture from Ileana spreads north.

Temperatures will be on the rise this weekend across the Central U.S. and
Northeast, with high temperatures forecast to reach values as high as
10-15 degrees above normal for this time of year. Highs in the 80s and 90s
will be common for the Plains, Upper Midwest/Great Lakes, and Northeast.
Precipitation and cloud cover from Francine will keep temperatures below
average for much of the Southeast. Temperatures across much of the West
will be near to slightly below average through Saturday. On Sunday, the
Pacific frontal system will usher in cooler, unsettled weather, and
temperatures will drop to well below normal along the West Coast.

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.