EconCurrents

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

…Great Lakes heavy lake-effect snow expected to continue into Friday
especially along the Snow Belt of the lower Great Lakes…

…A couple rounds of heavy coastal rain and heavy mountain snow expected
to impact northern California into Sierra Nevada heading into the
weekend…

…Sub-zero temperatures expected over parts of the northern Plains and
upper Mississippi Valley for the next couple of mornings…

As a deep low pressure system races further northward into eastern Canada
and a potent cold front exits New England this morning, an arctic high
pressure system will take over the northern Plains and expand across the
entire eastern U.S. through the next couple of days. Maine will be the
last to clear out from the heavy rain early this morning followed by much
colder temperatures under blustery westerly winds. The resurgence of
arctic air is triggering a new round of heavy lake-effect snow across the
Great Lakes through today and tonight before gradually tapering off on
Friday. The Snow Belt of the lower Great Lakes can expect a foot or more
of new snow, with locations downwind from Lake Ontario possibly getting
more than 2 feet since these locations will be the last to clear out from
the snow late on Friday.

Along the West Coast, moisture ahead of the next Pacific cyclone is poised
to overspread much of the Pacific Northwest and a good portion of
California today. The heaviest precipitation is expected to reach
northern California in form of rain near the coast and lower elevations.
A quick round of moderate to heavy snow will then reach the high
elevations farther inland and then along the Sierra Nevada for much of
today. It appears that this latest around of precipitation will taper off
temporarily tonight before the next round of precipitation associated with
the next Pacific cyclone arrives on Friday. Northern California into
southwestern Oregon can expect heavy precipitation Friday night with a
marginal risk of excessive rainfall continuing into Saturday morning by
the end of the short-range forecast period. Lesser amounts of
precipitation are expected for the Pacific Northwest.

The arctic high pressure system that is forecast to bring sub-zero
temperatures for the next couple of mornings is forecast to strengthen and
slide east into New England by Saturday morning. This will allow
southerly flow to increase across the southern Plains along with moisture
returning from the Gulf of Mexico by Friday night. Meanwhile, residual
energy associated with the first Pacific system is forecast to exit the
southern Rockies and induce the formation of a low pressure system over
the central Plains by Friday night. Some thunderstorms along with heavy
rain could quickly develop and move across the central Plains early on
Saturday ahead of the new low pressure system. Colder air could support
areas of mixed rain and snow farther north across the north-central Plains
into the upper Midwest in advance of the low pressure center. In the
short-term though, dry, breezy and relatively mild conditions will support
elevated fire danger across the southern High Plains for today.

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

…Widespread heavy rain and severe thunderstorm treats spreading up the
East Coast today and through New England into tonight…

…A surge of cold air into the eastern U.S. today will be followed by a
reinforcing surge of arctic air into the northern U.S. through the next
couple of days…

…Another round of significant lake effect snow expected through the next
couple of days downwind of the Lakes...

The stage is set for a rapidly intensifying low pressure system to track
up the East Coast today. A potent cold front trailing southwest from the
center of this elongated low pressure system will be the focus for heavy
rain, blustery winds, and strong to severe thunderstorms. Ahead of the
front, warm and moist air streaming in from the nearby Atlantic and Gulf
of Mexico will interact more vigorously with a jet stream aloft to develop
and expand the coverage of showers and thunderstorms, first across the
Southeast and the Carolinas this morning, followed by the Mid-Atlantic
states during the day, and into New England this evening. The highly
dynamic nature of this front will likely trigger formation of strong to
severe thunderstorms. This is especially the case across eastern North
Carolina this afternoon, and into southern New England this evening, where
the Storm Prediction Center has issued a Slight Risk (level 2 of 5) for
severe thunderstorms capable of producing damaging wind gusts. Elsewhere
along the Eastern Seaboard, the main concern will be a period of heavy
rain with embedded strong thunderstorms and intense downpours. Despite
much of the region currently experiencing moderate to extreme drought
conditions, the rain, while mostly beneficial, could lead to some
localized instances of flash flooding. The more urbanized locations and
poor drainage areas would have the greater risk of flooding issues.

Behind the potent cold front sharply colder air will surge into the East
Coast from the north and northwest. A period of accumulating wet snow can
be expected to spread up the western slope of the entire spine of the
Appalachians from south to north today through tonight. Meanwhile, a
reinforcing shot of arctic air is plunging into the northern Plains and
will overspread much of the northern tier states through the next couple
of days. High temperatures the next couple of days will be roughly 10 to
as much as 30 degrees below normal.

Attention then turns to yet another round of significant lake effect snow
downwind of the Great Lakes through the next couple of days. The
aforementioned surge of arctic air will stream across the still relatively
warm Great Lakes and ignite intense bands of lake effect snow, initially
downwind of Lakes Superior and Michigan on today and then downwind of
Lakes Erie and Ontario tonight into early Thursday. By the time the snow
starts to taper off on Friday, snowfall totals of 1 to 2 feet are likely
in the favored Snow Belt across portions of northwest and western New York
State, far northwest Pennsylvania, far northeastern Ohio, the Upper
Peninsula of Michigan and the western portions of the Lower Peninsula of
Michigan.

Along the West Coast, moisture ahead of the next cyclone from the Pacific
is poised to overspread much of the region through the next couple of
days. Northern California will see heavy coastal rain by this evening,
followed by heavy mountain snow farther inland and down the Sierra Nevada
where a foot or more of new snow is forecast through Thursday. It appears
that this round of precipitation will mostly taper off Thursday night
prior to the arrival of the next Pacific system.

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

…Widespread heavy rain threat emerging across the central to eastern
Gulf Coast region today will spread rapidly up the entire East Coast on
Wednesday…

…Active Lake effect snows to begin Wednesday and continue through
Thursday downwind of the Lakes…

…Record warm morning lows likely along the east coast Wednesday
morning…

…Arctic air to surge south into the Northern Plains/Upper Mississippi
Valley region late Tuesday into Wednesday…

…Santa Ana winds along with critical to extreme fire weather danger
across portions of southern California…

The upper-level flow pattern across much of North America will undergo
significant amplification over the next few days, producing various types
of impactful weather across mainland U.S. The most active weather in
terms of precipitation and winds will be the primary focus along the East
Coast through the next couple of days. Precipitation currently falling
across portions of the Southeast is in its organizing stage ahead of a
developing low pressure wave over the Mid-South along a cold front. As
the cold air behind the front interacts with a rapidly amplifying upper
trough, rain and embedded thunderstorms will rapidly expand northeastward
during the day Wednesday and up the entire East Coast, producing a period
of widespread heavy rainfall from the central to eastern Gulf coast,
across the Southeast, Mid-Atlantic, Northeast and New England. With much
of these areas currently in moderate to extreme drought conditions, this
rainfall will be beneficial. Still, given the potential for periods of
heavy rains over a short period, there will be a threat of localized flash
flooding, especially in more urbanized regions.

The cold front associated with this rapidly intensifying system will
become rather potent as it sweeps across the East Coast during the day on
Wednesday. There is potential for some very strong thunderstorms to form
ahead of the front together with heavy downpours. Meanwhile, drastically
colder air behind the front is forecast to produce accumulating snowfall
up the western slopes of the Appalachians on Wednesday together with
blustery northwesterly winds. The snow will then sweep across interior
New England through Wednesday night into Thursday morning as a potent
elongated low pressure system races northward into southeastern Canada.

With a warm southerly flow strengthening ahead of this potent front, there
is the potential for widespread record high morning low temperatures on
Wednesday across the southern Mid-Atlantic, Mid-Atlantic and portions of
the Northeast. In the wake of this front, much colder air will stream
across the Great Lakes from west to east beginning on Wednesday. This will
ignite active lake-effect snows, initially downwind of Lakes Superior and
Michigan on Wednesday and then downwind of Lakes Erie and Ontario
Wednesday night into early Thursday. Before these lake-effect snows
diminish by early Friday, snowfall totals of 1 to 2 feet are possible in
the favored Snow Belt across portions of northwest and western New York
State, far northwest Pennsylvania, far northeastern Ohio, the Upper
Peninsula of Michigan and the western portions of the Lower Peninsula of
Michigan.

The above-mentioned lake-effect snows will be driven by arctic air that
will be first surging east southeastward late Tuesday into early Wednesday
across the Northern Plains into the Upper Mississippi Valley and then
eastward trough the Great Lakes into the Ohio Valley on Wednesday. While
there are not expected to be any records with this arctic outbreak,
temperatures will be much below average on Wednesday across the Northern
Plains into the Upper Mississippi Valley. These much below average
temperatures will then push farther southeast into the Great Lakes and
Ohio Valley region on Thursday. Across these regions, high temperatures
will be 10 to 25 degrees below average during the height of the cold
temperatures during Wednesday and Thursday.

In contrast to the wet and cold conditions across portions of the
north-central to eastern U.S., dry condition and milder temperatures are
in store across the West coast, Great Basin and Rockies region. The dry
air, low relative humidities together with the latest episode of Santa Ana
winds across southern California will produce critical to locally extreme
fire weather danger. These fire weather conditions will be most prominent
in the higher terrain areas to the north and east of the Los Angeles to
San Diego region. Winds of 35 to 45 mph in the valleys and gusts of 50 to
65 mph in the mountains will help fan any fires that do develop quickly
and may reduce visibility with blowing smoke and dust adding to travel
concerns in the region. Across these areas, red flag warnings are
currently in effect, affecting nearly 13 million people.

By early on Thursday, the next round of coastal rain and mountain snow is
forecast to reach northern California as the next Pacific cyclone arrives.

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

…Heavy rain threat across the central to eastern Gulf Coast region today
will expand and move up the East Coast late Tuesday into Wednesday
morning…

…Periods of mixed rain and snow linger across interior New England
through tonight…

…Snow/blizzard conditions across the northern High Plains will gradually
taper off later today…

…Strong Santa Ana winds prompting critical fire danger across Southern
California…

…Well above average temperatures will overspread the central and eastern
U.S. as cold air surges into the western and then central U.S….

Increasingly active weather will progress toward the eastern U.S. through
the next couple of days as a weather pattern reversal continues to unfold
across the mainland U.S. One of the ingredients of this pattern change is
manifested by an expanding area of moderate to heavy rain moving through
the Ohio and Tennessee Valleys this morning with embedded thunderstorms
across the Deep South. The associated jet stream aloft will send the rain
rapidly northeastward across the Mid-Atlantic states today, reaching into
southern New England tonight. Temperatures will be cold enough to support
snow across northern New England Monday night into Tuesday morning before
tapering off for the time-being Tuesday afternoon. Meanwhile, an
extensive surge of cold air into the mid-section of the country will
reinvigorate the jet stream across the Deep South on Tuesday, leading to
an expanding area of moderate to locally heavy rain from the Gulf Coast
into the Deep South and interior Southeast. Tuesday night into Wednesday
morning will likely see the rain quickly expanding up the Appalachians and
into the interior section of the Mid-Atlantic, and then up into New
England with some ice possible at the onset. Meanwhile, organized lines
of thunderstorms could form ahead of a potent cold front across the
interior Southeast early on Wednesday along with sharply colder
temperatures and blustery northwesterly winds behind the front.

Across the northern High Plains, colder air and gale force winds behind a
low pressure system have prompted winter weather advisories/warnings,
Blizzard Warnings, as well as wind advisories/high wind warnings this
morning. 4-7″ of snow is expected across the northern High Plains.
Meanwhile, strong onshore flow off Lake Superior will further enhance
local snow totals across the Arrowhead of MN range where 9-12″+ totals are
expected.

On Tuesday, a more intense surge of cold air will be funneled southward
from Alaska and western Canada into the Plains associated with an
intensifying arctic high pressure system. A ‘Blue Norther’ cold front
will be driving well through the Southern Plains into northern Mexico by
Tuesday night, dropping temperatures into the 30s into southern Texas by
Wednesday morning. Meanwhile, a reinforcing cold front will drop
temperatures below zero degrees over the northern Plains by then. High
temperatures will be about 5-10 degrees below normal across much of the
Rockies, Southwest and eventually into the Plains.

Across the western U.S., a cold surge directed through the Great Basin
into the lower Colorado River Valley today will bring very strong Santa
Ana winds into southern California by later today. Given dry/low humidity
conditions already in place, Red Flag Warnings have been issued for the
eastern Transverse and all of the Peninsular Ranges; as well as a Critical
Fire (level 2 of 3) from the Storm Prediction Center. Winds of 35 to 45
mph in the valleys and gusts of 50 to 65 mph in the mountains will help
fan any fires that do develop quickly and may reduce visibility with
blowing smoke and dust adding to travel concerns in the region.

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

…Heavy rain threat emerges across the Deep South late Sunday into
Monday…

…Periods of mixed rain and snow linger from the Great Lakes to northern
New England through Monday night…

…Unsettled and windy weather spreading across the Pacific Northwest this
weekend will reach into the northern Plains as snow/wintry mix by Monday…

…Well above average temperatures will overspread the central and eastern
U.S. as cold air surges into the western U.S….

A major reversal of the weather pattern is forecast to occur across
mainland U.S. during the next couple of days. The remaining cold air
across the eastern U.S. originated from the recent arctic outbreak will be
dispelled by an eastward expanding mild air mass from the central U.S.
Meanwhile, the mild air across the western U.S. in recent days will be
dispelled by a surge of cold air currently advancing through the
northwestern U.S. The upper-level trough responsible for this cold surge
into the western U.S. will first spread mixed rain and snow through the
northern Rockies today behind a cold front along with windy conditions.
Daytime heating will keep the precipitation mainly in the form of rain as
it moves quickly across the northern Plains today. By tonight, colder air
from Canada is forecast to filter south from Canada behind a low pressure
system. This will bring periods of snow into the northern Plains and
areas farther west to the foothills of the northern Rockies through
tonight and into Monday, along with windy conditions. The higher elevations
will receive higher amounts of snow, with the highest snowfall likely near
the northern slopes of the Black Hills where more than a foot of new snow
is possible. Portions of the central Rockies into the Front Range of
Colorado and down into northeastern New Mexico can expect to receive a
period of snow from this system through Monday night into Tuesday morning.

Ahead of the cold front trailing south from the aforementioned low
pressure system, a jet stream sliding across northern Mexico will interact
with a coastal front and a low pressure wave near the western Gulf Coast
to bring an increasing threat of heavy rain farther inland across the
lower Mississippi Valley and then into the Deep South through the next
couple of days. Warmer and more unstable air arriving from the Gulf will
help trigger heavier showers and thunderstorms for the eastern portion of
these areas. The overlapping elements coupled with some recent rainfall
will result in the possibility of scattered instances of flash flooding.
The Weather Prediction Center maintains a Marginal Risk of Excessive
Rainfall across the central Gulf Coast region for Monday into early
Tuesday, with a Sight Risk area from southeastern Louisiana to southern
Mississippi.

Across New England, widespread snowfall is in progress today ahead of a
clipper system moving quickly eastward along a warm front lifting north
across the region. Widespread snowfall of up to 6 inches can be expected
from the Adirondacks eastward through Maine before the snow tapers off
tonight. More snow will then skirt the upper Great Lakes ahead of the
warm front associated with the northern Plains low pressure system, with
6-8 inches expected over the Upper Peninsula of Michigan and the Arrowhead
of Minnesota. A period of rain will sweep across the Ohio Valley Sunday
night, then the Appalachians and the northern Mid-Atlantic on Monday ahead
of the trailing front, followed by the next round of snow across northern
New England Monday night. Mild Atlantic air will keep the precipitation
as rain for southern New England into Tuesday morning.