Posts by Sig Silber

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EST Mon Jan 20 2025
Valid 00Z Tue Jan 21 2025 - 00Z Thu Jan 23 2025

...Dangerously cold temperatures and wind chill values to linger for much
of the South and eastern third of the nation through mid-week...

...Rare winter storm to bring heavy snow as well as areas of sleet and
freezing rain to the Gulf Coast and Southeast with widespread impacts...

...Extremely Critical Risk of Fire Weather for southern California will
continue into Tuesday...

A bitterly cold arctic airmass is currently in place for locations east of
the Rockies with well below average temperatures extending from the High
Plains to the East Coast. Wind chill values of 40 to 55 degrees below zero
will linger within the core of the coldest air from the northern Plains
into the Upper Mississippi Valley through Tuesday morning. Wind chill
values that are below zero will affect a broad portion of the lower 48
extending from the southern High Plains into the Ohio River Valley and
northern Mid-Atlantic region with wind chills in the teens and single
digits possible for portions of the Gulf Coast. These extreme cold
conditions will pose a risk of hypothermia to individuals not dressed
appropriately as well pose potential for frozen pipes and damage to
sensitive vegetation.

While much warmer temperatures are forecast for the northern Plains
tomorrow, the cold temperatures will continue from the Midwest to the
southern Plains to the East Coast tomorrow and Wednesday. High
temperatures for these regions on Tuesday are expected to be 20 to 30
degrees below mid-January averages and lows will drop below freezing for
all locations east of the Rockies except for central and southern Florida.

With the cold air in place, wintry precipitation is expected to overspread
south-central Texas to the central Gulf Coast tonight as an upper level
disturbance passes over the southern Plains. Snow or a snow/sleet mix is
likely for cities from San Antonio to Houston and New Orleans to Albany,
GA while freezing rain falls on South Texas and portions of southern
Georgia and northern Florida as the unusual winter storm tracks east on
Tuesday/Tuesday night. A narrow stripe of 4 to 6 inches will be possible
from southeastern Texas into southern Louisiana. Light accumulations of
snow are expected from the Florida Panhandle to the beaches of the
Carolinas. This winter storm is likely to result in major travel
disruptions, including significant traffic impacts on area highways, power
outages as well as flight delays/cancellations for these areas that are
not accustomed to impactful winter weather.

Conditions will begin to warm for the western U.S. into the middle of the
week but the continued dry conditions and dangerous Santa Ana winds will
contribute to Extremely Critical fire weather conditions for southern
California through the remainder of today into at least Tuesday morning.
Winds for coastal locations could gust into the 50-70 mph range while wind
gusts to near 100 mph will be possible in the mountains and foothills.
While some improvement is possible later on Tuesday, conditions will
remain dangerous with additional rounds of gusty offshore winds which will
continue through Wednesday.

Elsewhere, bands of heavy lake effect snow will continue the next couple
of days for favorable downwind locations of the Great Lakes with
persistent northwesterly flow in place.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Jan 20 2025
Valid 12Z Mon Jan 20 2025 – 12Z Wed Jan 22 2025

…Dangerously cold temperatures in place from the Rockies to the East
Coast…

…Rare, significant winter storm to bring a swath of heavy snow as well
as areas of sleet and freezing rain to the Gulf Coast and Southeast…

…Extremely Critical Risk of Fire Weather for southern California
Monday…

A bitterly cold arctic airmass has overspread the interior western,
central, and eastern U.S. following a strong cold front passage over the
weekend. Forecast high temperatures Monday from the Great Basin/Rockies
east to the East Coast will be upwards of 20-30 degrees below January
averages, ranging from the negative teens and single digits in the
northern Plains/Upper Midwest; the single digits and teens in the Rockies,
central Plains, and Midwest; the teens and 20s for New England and the
Mid-Atlantic; and the 20s and 30s for the Great Basin, southern Plains,
and Southeast. Life-threatening wind chills of 30 to 55 degrees below zero
at times are expected across the Rockies, northern Plains, and Upper
Midwest through Tuesday morning. Wind chills of this nature pose an
extreme risk of hypothermia and frost bite to exposed skin. Sub-zero wind
chills will reach as far south as the south-central Plains and east into
the Ohio Valley through Wednesday. Numerous Freeze Warnings are in place
along the Gulf Coast and northern Florida as sub-freezing morning lows
will pose a risk to sensitive vegetation and exposed plumbing for
locations not as accustomed to harsh Winter temperatures. Unfortunately,
these conditions look to remain in place across the eastern and southern
U.S. through the next few days. Upper-level ridging expanding across the
northwestern tier of the country will bring relatively warmer, more
seasonable Winter temperatures to portions of the Great Basin/Rockies as
well as the northern/central Plains on Tuesday, with highs back into the
20s, 30s, and 40s.

In addition to the frigid temperatures, the combination of such cold air
reaching the Gulf Coast and a developing low pressure system will lead to
a rare, significant winter storm for the Gulf Coast States and Southeast.
Impacts will begin Monday evening across eastern and southern Texas,
spreading eastward along the Gulf Coast and through the Southeast through
Tuesday and Wednesday. Heavy snow is expected along and north of the
Interstate 10 corridor with swaths of sleet and freezing rain over
portions of southern Texas and southeast Georgia/northern Florida. Major
travel disruptions are likely and flight delays/cancellations are expected
given that these areas are not accustomed to impactful Winter weather.
Power outages in areas of significant snow and ice are possible, and will
exacerbate impacts from the frigidly cold temperatures that will also be
in place.

Conditions will remain closer to average temperaure-wise for the West
Coast, particularly in California where forecast highs are in the 50s and
60s. Unfortunately, the mild temperatures as well as low humidity and the
return of very strong winds will lead to dangerous fire weather conditions
for southern California Monday into Tuesday. The Storm Prediction Center
has issued a Critical Risk of Fire weather (level 2/3) for southern
California as gusts to 60 mph for lower elevations and 75 mph and higher
in the foothills are expected. An Extremely Critical Risk (level 3/3) is
in place for the sensitive, ongoing fire areas of the San Gabriel and
Santa Monica Mountains.

Elsewhere, bands of heavy lake effect snow will continue the next couple
of days for favorable downwind locations of the Great Lakes with
persistent northwesterly flow in place. An upper-level wave will encourage
snow showers with some accumulations possible for portions of the
central/southern Rockies and Plains on Monday, while a clipper system
dropping south from Canada will bring snow showers to the northern
Rockies/Plains and Upper Midwest Tuesday into Tuesday night.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sun Jan 19 2025
Valid 12Z Sun Jan 19 2025 – 12Z Tue Jan 21 2025

…Winter storm to bring moderate to heavy snow to the Mid-Atlantic and
Northeast Sunday…

…Intrusion of Arctic Air bringing dangerously cold conditions to much of
the nation...

…Impacts from a rare, significant winter storm across the South next
week will begin for Texas Monday night…

…A Critical Risk of Fire Weather returns for southern California
Monday…

A winter storm is forecast to produce heavy snow across portions of the
Mid-Atlantic and Northeast today (Sunday). Some snow showers over the
Ohio/Tennessee Valleys and rain showers in the Southeast will linger into
Sunday morning following the passage of a cold front off the East Coast.
Meanwhile, an upper-level wave will help to deepen an area of low pressure
along a cold front Sunday morning which will move to the northeast just
off the coast through Sunday night. This will lead to a band of enhanced
snowfall developing inland to the northwest of the low track over the
Appalachians Sunday morning and from the northern Mid-Atlantic into New
England during the day. The heaviest snow will likely stay to the north
and west of the I-95 corridor. However, 3-6″ of snow with locally higher
amounts is expected form northern Maryland through Boston. Some
rain/wintry mix will be possible from northern Virginia to southern New
Jersey.

Precipitation chances elsewhere through Monday include bands of heavy
lake-effect snow for favorable downwind locations of the Great Lakes with
cold northwesterly flow in place. Some snow showers will return to the
central/southern Rockies and adjacent High Plains on Monday as a shortwave
passes over the region and in the presence of post-frontal upslope flow.

Another big story this weekend and heading into next week will be the
bitterly cold Arctic airmass spreading across most of the central/eastern
U.S. Temperatures have already plummeted across the Rockies, Plains, and
Mississippi Valley, and will reach the East Coast Sunday as the noted cold
front pushes offshore. This will be the coldest air of the Winter season
thus far, and in many cases the coldest in several years. Forecast highs
the next couple of days range from below zero to the single digits in the
northern Plains/Upper Midwest; the single digits and teens across the
Rockies, central Plains, and Midwest; the teens and 20s across the
Northeast and Mid-Atlantic; and the 20s and 30s for Texas and the
Southeast. Wind chills will reach dangerously cold levels, with minimum
wind chills from 30 to 55 below zero at times Sunday and Monday in the
Rockies, northern Plains and Upper Midwest. Sub-zero wind chills are
expected to reach as far south as Oklahoma and the Tennessee/Ohio Valleys
by Sunday night.

The combination of this frigid air reaching the Gulf Coast and the
development of a low pressure system over the Gulf will lead to a
significant winter storm across the Gulf Coast/Southeast next week.
Initial impacts are expected to begin by late Monday night across eastern
and southern Texas. A corridor of potentially heavy snow is expected near
and just south of the Interstate 20 corridor, with a wintry mix of snow,
sleet, and freezing rain closer to the Interstate 10 corridor. Given the
rare southerly track of this winter storm, major traffic and travel
disruptions are likely through mid-week.

Some of this Arctic airmass will reach portions of the Great
Basin/Interior West as well, with highs by Monday only in the 20s and 30s
for most locations. Forecast highs are generally more mild and around
average along the West Coast, with 40s for the Pacific Northwest, the 50s
and 60s for California, and the 60s to low 70s for the Desert Southwest.
Unfortunately, these mild conditions along with gusty winds and very low
humidity have prompted the Storm Prediction Center to issue a Critical
Risk of Fire Weather (level 2/3) Monday for southern California.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Sat Jan 18 2025
Valid 12Z Sat Jan 18 2025 – 12Z Mon Jan 20 2025

…Winter storm to bring moderate to heavy snow to the Mid-Atlantic and
Northeast Sunday…

…Snow showers with moderate accumulations continue Saturday through the
central Rockies and adjacent central/southern High Plains…

…Arctic front brings dangerous cold to much of the nation this weekend…

Moisture lifting northward ahead of a storm system/cold front pushing
through the eastern U.S. will bring wintry precipitation to the north and
rain and thunderstorms to the Southeast Saturday. A light to moderate
wintry mix is expected to move from the Great Lakes into the Appalachians
and interior Northeast, with mostly light rain showers elsewhere in the
Ohio Valley/Southeast and along the East Coast. An enhanced flow of Gulf
moisture over northern Florida will bring some more intense showers and
thunderstorms Saturday night with locally heavy rainfall and the risk for
some isolated flash flooding. A changeover to snow is expected Saturday
night for the Ohio/Tennessee Valleys following cold frontal passage,
though accumulations should generally remain light. Then, an upper-level
shortwave traversing the southern U.S. will help to encourage the
development/deepening of an area of low pressure as it moves off the coast
of the Mid-Atlantic. This will lead to an enhanced swath of snow to the
northwest of the low track beginning early Sunday morning across the
Appalachians and continuing into the day Sunday from the northern
Mid-Atlantic to New England. The swath of heaviest snow (5-8″+) will
likely stay just to the north and west of the I-95 corridor. However, 3-6″
of snow with locally higher amounts is expected from northern Maryland
through Boston. Lake-effect snow will also continue this weekend for
favorable locations downwind of the Great Lakes with strong northwesterly
flow in place following the frontal passage.

Elsewhere, snow showers will continue Friday for portions of the Rockies
and adjacent central/southern High Plains in post-frontal upslope flow.
Moderate totals of 3-6″ are possible in vicinity of the Raton Mesa.
Otherwise, the rest of the central/western U.S. will be mostly dry this
weekend.

Besides the impactful winter weather, dangerously cold temperatures
spreading across much of the Lower 48 this weekend and into next week will
be the other big weather story. Arctic air will plunge southward Saturday
over the Rockies, Plains, and Midwest following the cold frontal passage,
and will reach the East Coast Sunday night as the front moves off into the
Atlantic. Forecast highs by Sunday range from below zero to the single
digits in the northern Plains/Upper Midwest, the teens and 20s across the
central Plains and Midwest, the 20s and 30s for the southern Plains and
Lower Mississippi Valley, and the 40s along the western and central Gulf
Coast. These temperatures will spread to the East Coast for highs Monday,
just beyond the forecast period. Dangerously cold wind chills of 30-55
degrees below zero are expected across the Rockies, northern Plains, and
Upper Midwest Sunday and continuing into next week. This will pose a
life-threatening risk of hypothermia and frostbite to exposed skin. Wind
chills below zero will reach as far south as Oklahoma and the Tennessee
Valleys. Temperatures will remain near average west of the Rockies, with
30s and 40s for the Interior West/Pacific Northwest, the 50s and 60s in
California, and the 60s and 70s in the Desert Southwest.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Fri Jan 17 2025
Valid 12Z Fri Jan 17 2025 – 12Z Sun Jan 19 2025

…Arctic front begins to bring hazardous cold to much of the nation this
weekend…

…Wintry mix for the Midwest/Northeast and rain for the Southeast Friday
into Saturday…

…Snow showers with some moderate accumulations expected through the
Northern/Central Rockies and adjacent High Plains…

A clipper system will move quickly across the northern Plains into the
Midwest Friday and the Northeast by Saturday, bringing a wintry mix of
rain and snow showers ahead of a sweeping cold front. Precipitation totals
should remain on the lighter side for most locations through Saturday,
with only some light snow accumulations expected for some of the higher
elevations of the Appalachians. More moderate totals are expected where
post-frontal flow across the Great Lakes will lead to some lake-effect
snow showers for favorable downwind locations, especially along the Upper
Peninsula of Michigan and east of Lake Ontario. Some potentially more
impactful snow is becoming more likely for the Northeast on Sunday just
beyond the current forecast period. Further South, moist return flow from
the Gulf of Mexico will lead to heavier rain showers ahead of the trailing
cold front through the Middle Mississippi/Ohio Valley and the Southeast
late Friday and into early Saturday. Some wintry precipitation will be
possible following the frontal passage for the Ohio/Tennessee Valleys on
Saturday. Showers and thunderstorms will continue ahead of the front as it
passes into northern Florida by Saturday evening, with more potent locally
heavy downpours and isolated flash flooding possible.

This sweeping cold front will begin to usher in a frigid Arctic airmass
that will be one of the main national weather stories this weekend and
into the next week. Temperatures will plunge by 30-40 degrees Saturday
after above average conditions on Friday. Forecast highs Saturday range
from the single digits and teens in the northern Plains/Upper Midwest, the
teens and 20s for the central Plains and Midwest, and the 30s and 40s into
the Southern Plains/northern Texas. Wind chills upwards of 20-30 degrees
below zero are expected for the northern Plains. Unfortunately, this is
only just the tip of the iceberg, as even colder temperatures will expand
in coverage beyond the current forecast period. Conditions will be at or
above average ahead of the front along the East Coast and the Southeast
through Saturday, with highs the next couple of days in the 30s and 40s
for the Northeast, the 40s and 50s from the Ohio Valley east through the
Carolinas, and the 60s and low 70s for the Southeast.

Upslope flow following the passage of the front along the Rockies will
lead to some scattered snow showers with light to moderate accumulations
for the northern Rockies/High Plains Friday and the central and southern
Rockies/High Plains Friday into Saturday. Gusty winds are also expected
across portions of the Plains and along the Front Range of the Rockies.
This may lead to some blowing snow in the northern Plains. Dry conditions
are expected for the Great Basin and West Coast, with high temperatures
generally around average. Forecast highs range from the 30s and 40s in the
Great Basin, the 40s for the Pacific Northwest, the 50s and 60s in
California, and the 60s to low 70s in the Desert Southwest.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Thu Jan 16 2025
Valid 12Z Thu Jan 16 2025 – 12Z Sat Jan 18 2025

…Improvement in fire weather conditions across southern California…

…A brief moderation of temperatures across the central U.S. before an
arctic front plunges into the northern U.S. on Friday…

…Lake effect snow expected on Thursday and snow also expected for the
central Appalachians…

There will be a few things making weather headlines through Friday night
across the country. Lake effect snow is expected in the wake of a
shortwave passage, and the heaviest snowfall will be downwind of Lake Erie
across western New York on Thursday, where lake effect snow warnings are
now in effect. Moderate to heavy snow is also on the way for the central
Appalachians with moist upslope flow leading to 5-10 inches of
accumulation across the higher terrain of West Virginia into south-central
Pennsylvania, where winter storm warnings are in effect.

A pattern change will evolve across the Central U.S. and the Rockies going
into Friday and especially into early Saturday. After a brief moderation
in temperatures across the north-central U.S. on Thursday, an abrupt
change to reality is coming by Friday as a pair of strong cold fronts
heralds the arrival of frigid temperatures and brutally cold wind chills.
This will continue well beyond the short range forecast period, and the
Weather Prediction Center has Key Messages regarding this arctic blast.
This could also be accompanied by some snow showers and a few snow squalls
across the northern Rockies and western High Plains going into Friday and
Friday night, resulting in mainly light accumulations but accompanied with
poor visibilities and gusty winds.

For the Eastern U.S., a gradual moderation trend in the recent very cold
conditions is on the way to conclude the work week with readings returning
to near seasonal averages for the East Coast, and above average for much
of the Southeast states. A developing low pressure system over the Deep
South Friday night will likely lead to increasing showers and perhaps a
few thunderstorms near the central Gulf Coast region by Saturday morning,
but this region should remain dry until then.

Things are starting to look better in terms of the forecast across
California and the areas that have been devastated by the ongoing
wildfires. Even though no rain is in the forecast, the winds are expected
to switch to a more onshore flow late Thursday and into Friday, bringing
higher relative humidities and less chaotic wind flow, thus helping to
mitigate the wildfire threat compared to recent days.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Tue Jan 14 2025
Valid 12Z Tue Jan 14 2025 – 12Z Thu Jan 16 2025

…Extremely critical fire weather conditions will continue across coastal
Southern California today…

…Much below average temperatures from the Midwest to the central
Appalachians through Wednesday but warming into the central U.S. on
Thursday…

…Locally heavy lake effect snow showers downwind of the Great Lakes
through Wednesday…

Overall, the weather pattern across most of the lower 48 through Thursday
will feature a lack of precipitation with a warming trend later in the
week. This will be a reflection of broad upper level troughing over the
eastern two thirds of the nation and ridging over the Pacific Northwest,
forecast to migrate eastward through Thursday.

Coastal southern California will continue to see extremely critical fire
weather conditions through at least today with localized wind gusts near
70 mph focused across Ventura and Los Angeles counties. Very dangerous
conditions will continue into Wednesday for many of these same locations
with a broader, though not as extreme, threat extending along most of the
Transverse and Peninsular Ranges. Winds are expected to oscillate in
magnitude over the next 48 hours but the environment is expected to be
remain extremely dangerous, favorable to very rapid fire growth if a fire
does start.

After the passage of a cold front on Monday night across the eastern U.S.,
another surge of modified Arctic air will move across the Midwest today.
High temperatures will be 10 to 20 degrees below average for many
locations from the Upper Midwest through the Ohio Valley today, with the
cold continuing for the Ohio Valley on Wednesday. A change in wind
direction from northerly/northwestelry to westerly will accompany a warm
front on Wednesday across the north-central U.S. which will have the
effect of significant warming for the region. In fact, high temperatures
are forecast to jump about 20 degrees higher on Wednesday compared to
Tuesday for the north-central U.S., moving high temperatures from below
average to above average. The warmer weather will expand south and east
for Thursday but the East Coast will still remain a little below average.

The other consequence of the cold weather will be heavy lake effect snow
showers on the southeast and eastern shores of the Great Lakes. While
local wind direction will vary over the next couple of days, moving narrow
bands of heavy snow north or south, the heaviest accumulations of 1 to 2
feet (locally higher) are expected east of Lake Erie and Lake Ontario,
especially into the Tug Hill Plateau.

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
Mon Jan 13 2025
Valid 12Z Mon Jan 13 2025 – 12Z Wed Jan 15 2025

…Extremely dangerous fire weather conditions to develop across coastal
southern California early this week…

…Locally heavy lake effect snow showers downwind of Lakes Erie and
Ontario as renewed surge of arctic air moves through into the upper
Midwest and Ohio Valley…

The weather pattern across the lower 48 will feature upper level ridging
from the northeastern Pacific into the northwestern U.S., while upper
level troughing dominates much of the remaining area of the country. Below
average moisture across much of the lower 48 will result in a lack of
rain/snow for many areas of the lower 48 through Tuesday with the
exception of lake effect snow showers and scattered snow showers in and
around the northern/central Rockies into the High Plains.

The passage of a weak surface low and cold front through Florida today
will bring a gradual end to rainfall across portions of the southeastern
U.S. Meanwhile, another cold front, moving through the Ohio Valley this
morning, will be followed by another surge of Arctic air which will reach
the Midwest today and into the Mid-Atlantic and Northeast for Tuesday. The
cold front will be accompanied by snow showers today across the Northeast
with potential for isolated snow squalls which could result in hazardous
travel from sudden reduced visibilities, gusty winds and quick minor
accumulations of snow. High temperatures will be 10 to 20 degrees below
average today from the Upper Midwest to lower portions of the Ohio Valley.
The airmass will be modifying/losing vigor as it reaches the East Coast,
but will still be responsible for below average temperatures by Tuesday
for the Eastern Seaboard. Heavy lake effect snow showers are expected to
develop later today as the colder air moves across the Great Lakes, with
localized snowfall accumulations of 1-2 feet for isolated locations which
experience persistent banding through Tuesday night, mainly east of Lake
Erie and Lake Ontario.

The lack of precipitation across the CONUS will also include southern
California which has experienced a number of high profile wildfires over
the past week. Upper troughing aloft and increasing surface pressures over
the Great Basin will again lead to strong gusts across the typically
favored areas across coastal southern California today with winds peaking
between 40-50 mph. Conditions are expected to worsen for these locations
by Tuesday morning as wind gusts near 70 mph will be possible. When
combined with low relative humidities and a lack of recent rainfall (dry
fuels), a Particularly Dangerous Situation Red Flag Warning has been
issued for Santa Barbara, Ventura and Los Angeles Counties from Monday
night through Wednesday morning. These locations will be under a high risk
for large fires with potential for very rapid spreading of any fires that
may develop.