Sig Silber

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Oct 01 2024
Valid 12Z Tue Oct 01 2024 – 12Z Thu Oct 03 2024

…There is a Marginal Risk of excessive rainfall over parts of the
Mid-Atlantic and Florida on Tuesday…

…There is a Critical Risk of fire weather over parts of the Northern
High Plains on Tuesday…

…There are Excessive Heat Warnings and Heat Advisories over parts of
Southern California and the Southwest…

Upper-level energy over the Mid-Atlantic will slowly advance off the
Eastern Seaboard by late Tuesday night. Lingering moisture and upper-level
energy will produce moderate to heavy rain over parts of the Mid-Atlantic.
Therefore, the WPC has issued a Marginal Risk (level 1/4) of excessive
rainfall over parts of the Mid-Atlantic through Wednesday morning. The
associated heavy rain will create localized areas of flash flooding,
affecting areas that experience rapid runoff with heavy rain.

In addition, showers and thunderstorms will develop over parts of Florida
producing areas of moderate to heavy rain. Therefore, the WPC has issued a
Marginal Risk (level 1/4) of excessive rainfall over parts of Florida
through Wednesday morning. The associated heavy rain will create
localized areas of flash flooding, affecting areas that experience rapid
runoff with heavy rain.

Meanwhile, a front extending from the Upper Great Lakes to the Southern
Plains moves eastward to the Northeast and weakens. On Tuesday, the front
will produce light rain over parts of the Upper Great Lakes and by Tuesday
afternoon, rain will expand along the boundary from the Ohio Valley to the
Tennessee Valley. Light rain moves into the Lower Great Lakes/Central
Appalachians by Wednesday and into the Northeast/Mid-Atlantic by Wednesday
evening. In addition, showers and thunderstorms will develop over parts of
Florida from Tuesday into Thursday.

Further, upper-level ridging over the Northern Intermountain Region into
the Northern Rockies will create warm air associated with down-sloping
air, strong gust wind, and dry fuels, prompting a Critical Risk of fire
weather over parts of the North High Plains on Tuesday.

Elsewhere, a front moving onshore over the Pacific Northwest will move
inland to the Great Lakes by Thursday. The system will produce scattered
showers over parts of the Pacific Northwest on Tuesday.

Moreover, the upper-level ridge over the Four Corners Region will create
high temperatures over Southern California and the Southwest, ranging from
the upper 90s to 110s. Low temperatures will be in the upper 80s to low
90s, providing little relief from the heat overnight. The temperatures
have prompted Excessive Heat Warnings and Heat Advisories over parts of
Southern California and the Southwest.

Record-breaking heat is expected across portions of the Southwest.
Remember, Heat is the Deadliest Weather Phenomenon in the U.S.! People
spending more time outdoors or in a building without cooling are at an
increased risk of heat-related illness. Visit www.weather.gov/safety/heat
and check local media and government websites for cooling center
information.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Sep 30 2024
Valid 12Z Mon Sep 30 2024 – 12Z Wed Oct 02 2024

..There is a Slight Risk of excessive rainfall over parts of the Central
Appalachians/Mid-Atlantic on Monday…

…There is a Critical Risk of fire weather over parts of the
Northern/Central Plains on Monday…

…There are Excessive Heat Warnings and Heat Advisories over parts of
Southern California and the Southwest…

An upper-level low over the Ohio Valley/Central Appalachians will slowly
weaken and move eastward to the Mid-Atlantic by Tuesday, with the energy
moving off the Mid-Atlantic Coast by Tuesday evening. A rich pool of
moisture extends from the Tennessee Valley to the Ohio Valley, and then
the Mid-Atlantic will be impacted by upper-level dynamics to produce heavy
rain over parts of the Central Appalachians/Mid-Atlantic. Therefore, the
WPC has issued a Slight Risk (level 2/4) of excessive rainfall over parts
of the Central Appalachians/Mid-Atlantic through Tuesday morning. The
associated heavy rain will create mainly localized areas of flash
flooding, with urban areas, roads, small streams, and low-lying areas the
most vulnerable. On Tuesday, the threat of excessive rainfall ends. Rain
and showers will continue over parts of the Mid-Atlantic through Tuesday
night.

Meanwhile, a dry front extending from the Northern Plains to the Central
High Plains/Central Rockies will move to the Lower Upper Great Lakes
southwestward to the Southern Plains by Wednesday. On Tuesday, the front
will intersect moisture over the Upper Midwest, producing light rain over
parts of the Upper Great Lakes. By Tuesday afternoon, rain will expand
along the boundary from the Ohio Valley to the Tennessee Valley. Light
rain will move into the Lower Great Lakes/Central Appalachians by
Wednesday. In addition, showers and thunderstorms will develop over parts
of Florida from Monday into Wednesday.

Ahead of the front, an upper-level ridge will extend from the Southwest to
the Northern/Central Plains. The warm air associated with the upper-level
ridge, strong gust wind, and dry fuels have prompted a Critical Risk of
fire weather over the North/Central Plains on Monday.

Moreover, the upper-level ridge over the Four Corners Region will create
high temperatures over Southern California and the Southwest ranging from
the upper 90s to 110s. Low temperatures will be in the upper 80s to low
90s, providing little relief from the heat overnight. The temperatures
have prompted Excessive Heat Warnings and Heat Advisories over parts of
Southern California and the Southwest.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sun Sep 29 2024
Valid 12Z Sun Sep 29 2024 – 12Z Tue Oct 01 2024

…There is a Slight Risk of excessive rainfall over parts of the Central
Appalachians/Mid-Atlantic on Sunday and Monday…

…There is a Critical Risk of fire weather over parts of the
Northern/Central Plains on Sunday and Monday…

…There are Excessive Heat Warnings over parts of Southeastern California
and the Southwest…

An upper-level low over the Ohio Valley will slowly weaken and move
eastward to the Mid-Atlantic by Tuesday. A rich pool of moisture extends
from the Tennessee Valley to the Ohio Valley, and then the Mid-Atlantic
will be impacted by upper-level dynamics to produce heavy rain over parts
of the Central Appalachians/Mid-Atlantic. Therefore, the WPC has issued a
Slight Risk (level 2/4) of excessive rainfall over parts of the Central
Appalachians/Mid-Atlantic through Monday morning. The associated heavy
rain will create mainly localized areas of flash flooding, with urban
areas, roads, small streams, and low-lying areas the most vulnerable.

On Monday, the threat of excessive rainfall continues, however, over a
slightly smaller area. Once again, the moisture and upper-level energy
will aid in producing heavy rain over parts of the Central
Appalachians/Mid-Atlantic. Therefore, the WPC has issued a Slight Risk
(level 2/4) of excessive rainfall over parts of the Central
Appalachians/Mid-Atlantic from Monday through Tuesday morning. The
associated heavy rain will create mainly localized areas of flash
flooding, with urban areas, roads, small streams, and low-lying areas the
most vulnerable.

Meanwhile, a dry front will move from the Northern Rockies to the Upper
Great Lakes southwestward to the Southern Plains by Tuesday. Ahead of the
front, an upper-level ridge will extend from the Southwest to the
Northern/Central Plains. The warm air associated with the upper-level
ridge, strong gust wind, and dry fuels have prompted a Critical Risk of
fire weather over the North/Central Plains from Sunday through Monday.
The front will produce showers and thunderstorms over parts of the Upper
Great Lakes overnight Monday into Tuesday.

Moreover, the upper-level ridge over the Four Corners Region will create
high temperatures over Southeastern California and the Southwest that will
range from the upper 90s to 110s, and low temperatures will be in the
upper 80s to low 90s, providing little relief from the heat overnight. The
temperatures have prompted Excessive Heat Warnings over parts of
Southeastern California and the Southwest.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri Sep 27 2024
Valid 12Z Fri Sep 27 2024 - 12Z Sun Sep 29 2024

...HELENE is forecast to continue to move inland to the northwestward to
the Ohio Valley by Saturday while slowly weakening...

...There is a High Risk of excessive rainfall over parts of the Southern
Appalachians on Friday and a Slight Risk over parts of the Ohio Valley on
Saturday...

...There is an Enhanced Risk of severe thunderstorms over parts of the
southern Mid-Atlantic on Friday...

...There are Excessive Heat Warnings over parts of Southeastern California
and the Southwest...

HELENE is forecast to move inland, heading northwestward to the Ohio
Valley, and slowly weaken by Saturday. Showers and thunderstorms with
heavy rain will develop over parts of the Southern Appalachians and
southern Mid-Atlantic. Therefore, the WPC has issued a High Risk (level
4/4) of excessive rainfall over the Southern Appalachians through Saturday
morning.  Severe, widespread flash flooding is expected. In addition,
areas that normally do not experience flash flooding will flood. Lives and
property are in great danger.

Moreover, showers and severe thunderstorms will develop over parts of the
southern Mid-Atlantic. Therefore, the SPC has issued an Enhanced Risk
(level 3/5) of severe thunderstorms over the southern Mid-Atlantic through
Saturday morning.  The hazards associated with these thunderstorms are
frequent lightning, a few tornadoes, and a minimal threat of severe
thunderstorm wind gusts and hail. Also, rain will develop over parts of
the Ohio/Tennessee Valleys on Friday.

On Saturday, the excessive rainfall threat from HELENE lessens. However,
heavy rain will develop over parts of the Ohio Valley. Therefore, the WPC
has issued a Slight Risk (level 2/4) of excessive rainfall over parts of
the Ohio Valley from Saturday through Sunday morning. The associated heavy
rain will create mainly localized areas of flash flooding, with urban
areas, roads, small streams, and low-lying areas the most vulnerable.

Further, the threat of severe thunderstorms ends on Saturday. Yet showers
and thunderstorms will develop over the Florida Peninsula. Additionally,
rain will continue over the Ohio/Tennessee Valleys and parts of the
Mid-Atlantic through Sunday morning.

Meanwhile, a front will move onshore over the Pacific Northwest and inland
to the Northern Plains. The system will produce rain over parts of the
Northwest ending by late Friday afternoon.

In addition, an upper-level high will remain over the Southwest through
Sunday. High temperatures will range from the upper 90s to 110s, and low
temperatures in the mid to upper 80s will provide little relief from the
heat overnight. The temperatures have prompted Excessive Heat Warnings
over parts of Southeastern California and the Southwest. 

alid 12Z Fri Sep 27 2024 - 12Z Sun Sep 29 2024 ...HELENE is forecast to continue to move inland to the northwestward to the Ohio Valley by Saturday while slowly weakening... ...There is a High Risk of excessive rainfall over parts of the Southern Appalachians on Friday and a Slight Risk over parts of the Ohio Valley on Saturday... ...There is an Enhanced Risk of severe thunderstorms over parts of the southern Mid-Atlantic on Friday... �There are Excessive Heat Warnings over parts of Southeastern California and the Southwest� HELENE is forecast to move inland, heading northwestward to the Ohio Valley, and slowly weaken by Saturday. Showers and thunderstorms with heavy rain will develop over parts of the Southern Appalachians and southern Mid-Atlantic. Therefore, the WPC has issued a High Risk (level 4/4) of excessive rainfall over the Southern Appalachians through Saturday morning. Severe, widespread flash flooding is expected. In addition, areas that normally do not experience flash flooding will flood. Lives and property are in great danger. Moreover, showers and severe thunderstorms will develop over parts of the southern Mid-Atlantic. Therefore, the SPC has issued an Enhanced Risk (level 3/5) of severe thunderstorms over the southern Mid-Atlantic through Saturday morning. The hazards associated with these thunderstorms are frequent lightning, a few tornadoes, and a minimal threat of severe thunderstorm wind gusts and hail. Also, rain will develop over parts of the Ohio/Tennessee Valleys on Friday. On Saturday, the excessive rainfall threat from HELENE lessens. However, heavy rain will develop over parts of the Ohio Valley. Therefore, the WPC has issued a Slight Risk (level 2/4) of excessive rainfall over parts of the Ohio Valley from Saturday through Sunday morning. The associated heavy rain will create mainly localized areas of flash flooding, with urban areas, roads, small streams, and low-lying areas the most vulnerable. Further, the threat of severe thunderstorms ends on Saturday. Yet showers and thunderstorms will develop over the Florida Peninsula. Additionally, rain will continue over the Ohio/Tennessee Valleys and parts of the Mid-Atlantic through Sunday morning. Meanwhile, a front will move onshore over the Pacific Northwest and inland to the Northern Plains. The system will produce rain over parts of the Northwest ending by late Friday afternoon. In addition, an upper-level high will remain over the Southwest through Sunday. High temperatures will range from the upper 90s to 110s, and low temperatures in the mid to upper 80s will provide little relief from the heat overnight. The temperatures have prompted Excessive Heat Warnings over parts of Southeastern California and the Southwest.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Sep 24 2024
Valid 12Z Tue Sep 24 2024 – 12Z Thu Sep 26 2024

…Potential Tropical Cyclone Nine is forecast to pass not too far from
the Florida Keys Wednesday night as a hurricane before skirting up the
West Coast of Florida by Thursday morning…

…Much needed rainfall from the Ohio Valley into the central to southern
Appalachians, Upper Tennessee Valley and Mid-Atlantic…

…Much above average temperatures continue across the West into the
Northern Plains and across the Gulf Coast into the Southeast…

A relatively benign mid- to upper-level trough that will likely bring
beneficial rainfall for the eastern U.S. is forecast to deepen when
another upper-level trough over the northern Plains drops southeast and
merges with the lead trough. The resulting trough amplification will be
instrumental in pulling the tropical moisture as well as Potential Cyclone
Nine (PTC9) northward into the eastern portion of the Gulf of Mexico by
the end of the short-range forecast period on Thursday morning.

The initial impacts from the lead trough will be in the form of an
expanding area of moderate to heavy rainfall potential from the Midwest
into the lower Great Lakes, Ohio Valley, upper Tennessee Valley, central
to southern Appalachians into the Mid-Atlantic near and ahead of a low
pressure wave. Much of these areas are currently experiencing severe to
exceptional drought conditions, with the expected 1 to 1.5 inch plus
rainfall amount over the next two days bringing some relief to these
drought conditions. With the dry conditions across these areas, river
flooding will be unlikely. However, there is still at least a marginal
risk of isolated flash flooding with the expected heavy rainfall amounts,
especially if they occur over urbanized regions.

As the above-mentioned amplifying pattern develops over the northern
Plains and dips toward the Deep South, PTC9 is forecast to track more
toward the north and intensify rapidly as it moves across the Yucatan
Channel on Wednesday and then pass not too far from the Florida Keys
Wednesday night. The Florida Keys can expect strengthening winds with
more frequent passages of squally downpours Wednesday night as PTC9 is
forecast to pass to the west as a hurricane. Computer models indicate
that the circulation of PTC9 will expand as it interacts with the
deepening upper trough in the Deep South. Given a more robust convective
structure concentrated more on the east side of the storm, the West Coast
of Florida could begin to see more frequent and intense squalls with winds
further strengthening by Thursday morning. Please refer to the National
Hurricane Center for the latest updates on this system.

The amplifying upper ridge across the interior West will be supporting
widespread much above average temperatures over the next few days across
nearly all of the West and into the Northern Plains. High temperatures
across these regions are forecast to be as much as 10 to 20 degrees above
average. Above average temperatures also likely across the Gulf Coast and
into the Southeast. While temperatures are forecast to be much above
across these areas over the next few days, there are not expected to be
many record highs. However, more numerous record high morning
temperatures are possible both today and Wednesday morning along the West
coast and from portions of the southern Mid-Atlantic into the Southeast
and Florida. Across the Pacific Northwest, the cold front associated
with a Pacific cyclone centered over the Gulf of Alaska will only bring
some rainfall into the region by Wednesday.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Sep 23 2024
Valid 12Z Mon Sep 23 2024 – 12Z Wed Sep 25 2024

…Threat of heavy rain and locally strong to severe thunderstorms will
slowly shift from the southern Plains this morning to the Ohio Valley,
central Appalachians and lower Great Lakes on Tuesday into early
Wednesday…

…Watching the western Caribbean Sea for tropical cyclone formation that
could bring strengthening winds and passing squally downpours into the
Florida Keys Tuesday night into Wednesday morning…

A low pressure consolidating over the southern Plains along a slow-moving
front is forecast to move northeastward through the Mid-Mississippi Valley
by tonight, then across the Midwest and Ohio Valley on Tuesday. Heavy
showers and some severe thunderstorms this morning across the southern
Plains are expected to taper off as today progresses but the threat of
heavy rain and locally strong to severe thunderstorms will increase from
the Mid-Mississippi Valley into the Midwest in the mean time. By Tuesday,
the center of the low will pass through the Midwest toward the lower Great
Lakes, the threat of heavy rain and embedded strong thunderstorms will
then develop well ahead of the low across the Ohio Valley, mainly from
Tuesday afternoon into Tuesday night. By early Wednesday, many areas
across the lower Great Lakes and the interior East Coast will be
enshrouded by showers and embedded thunderstorms. These showers and
storms will extend farther southwest near/along the trailing front across
the interior Gulf Coast states. Showers and periods of rain will also
move across the lower Great Lakes into the central Appalachians and
upstate New York in association with another wave of low pressure near the
front.

The upper-level low behind the slow-moving front will slide across the
central Plains, allowing much of the western U.S. to remain dry along with
a warming trend for the next couple of days. Meanwhile, colder air will
remain entrenched across the Plains behind the front but 90s will be
common in the afternoon across the South and into the interior Southeast
today and Tuesday ahead of the front. The outer edge of a Pacific cyclone
centered over the Gulf of Alaska will only bring some light rain into
northwestern Washington State this morning.

Farther south into the tropics, the National Hurricane Center continues to
watch the western Caribbean Sea for potential tropical cyclone formation.
Computer models now appear to be in good agreement for the system to move
northwestward and reach the Yucatan Channel by the time the short-range
forecast period ends Wednesday morning. This means that the Florida Keys
could experience strengthening winds along with passing squally downpours
from Tuesday night into Wednesday morning. Please refer to the National
Hurricane Center for the latest updates on this system.