EconCurrents

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.