NWS Hastings, NE wrote its last area forecast discussion before the first event at Jan 8, 6:07 AM CST, 53 minutes earlier. Its key messages:
Area forecast discussion, Jan 8, 6:07 AM CST, 53 minutes before
Area Forecast Discussion
National Weather Service Hastings NE
607 AM CST Mon Jan 8 2024
...Aviation Update...
.KEY MESSAGES...
- A significant winter storm will impact our entire coverage
area (CWA) to varying degrees today into tonight, with the
majority of FALLING snow occurring this morning through this
evening, but the worst impacts from blowing/drifting snow
ramping up from west-to-east this afternoon-overnight as
northerly winds gust as high as 40-50 MPH. MOST places now
expected to pick up between 5-10" of snow.
- Roughly the southwest half of our CWA (including the Tri
Cities) has been converted to a Blizzard Warning as those
counties are overall most-favored to experience a few hours of
blizzard conditions later today-tonight as winds ramp up, but
at least near-blizzard conditions are also probable elsewhere
in our CWA where a Winter Storm Warning continues.
- Our active weather pattern continues beyond the current storm,
with a chance for a touch of light snow returning already
Wednesday, and perhaps a better chance for accumulating snow
during the Thurs-Fri time frame (uncertainty high, but does
not appear nearly as significant as current system.
- Starting especially Thursday night onward (likely into the
first part of NEXT week...beyond our current 7-day forecast),
we will need to brace for what will likely be our overall-
coldest, multiple-day stretch since the infamous Feb. 2021
cold air outbreak. Several days of single-digit high temps
appear probable, along with several overnight-morning wind
chills of at least -15 to -30 degrees (probably eventually
prompting Advisories and possible Warnings).
&&
.DISCUSSION...
Issued at 533 AM CST Mon Jan 8 2024
UP FRONT NOTE: in the interest/necessity of time, the ENTIRE
remainder of this discussion will focus solely on these next 48
hours, and particularly on the impending winter storm. The most
important items in our longer term forecast are outlined in Key
Messages above.
-- VARIOUS NOTES/ITEMS COMPLETELY RELATED TO THE IMPENDING
WINTER STORM:
- Meteorological basics/general expectations:
In the mid-upper levels, water vapor satellite imagery and short
term model data clearly depict a vigorous closed low/vort max
churning over eastern NM, with the exit region of a powerful
100+KT upper level jet streaming northeastward along its
periphery, and promoting increased lift into our area within its
left exit region. At the surface, a roughly 996 millibar low s
centered over the northeast NM/TX Panhandle border area. Out
ahead of the surface low, an impressive southerly low level jet
has resulted in impressive (for January) warm air/moisture
advection into our region, and there is even up to a few hundred
J/kg of elevated instability/CAPE noted over our KS/southern
zones, where some rain showers (possibly with some sleet) have
already developed and the possibility exists for some weak
thunderstorms.
Over the course of today, the warm air advection will steadily
be replaced by cold air advection as the nearly vertically
stacked upper/surface lows move east into northwest OK, causing
our surface/level winds to turn northerly and increase across
our CWA with time from west-to-east. Although this low pressure
track is typically a touch too far south to bring us significant
precipitation/snowfall, latest model runs have keyed in on
impressive lift/forcing/frontogenesis to the north of the main
low, with a significant expansion (explosion?) of moderate-
heavy precipitation likely to break out over the entire CWA this
morning, but the overall-heaviest amounts targeting roughly the
southeast 2/3rds of our CWA. For the vast majority of the CWA,
precipitation type will be snow (heavy at times). However
through at least mid-morning (9-10 AM) lingering warm air aloft
could keep precip type as mainly rain (and possibly sleet in
convective cores) in parts of our KS zones up toward the Hebron
area. However, even much of this area should turn to snow by
mid-late morning as the low-levels cool aided by strong dynamic
forcing/lifting processes.
This evening-tonight into Tues AM, the powerful upper
level/surface storm system will reach southern MO, with our
winds ramping up and turning more northwesterly in a tight
pressure gradient, with with snow gradually becoming lighter in
nature while ending from west-to-east. By sunrise, especially
the western 2/3rds of our CWA will be snow-free, but lingering
light snow might take closer to 9-10 AM to fully vacate our far
eastern zones. Even as falling snow exits, tonight into Tues AM,
strong north-northwest winds gusting as high as 40-50 MPH
(anything over 45 would likely be an exception) will promote
continued blowing/drifting snow issues.
Finally, Tuesday afternoon will not only bring steadily
decreasing winds (actually fairly light by sunset...only around
10 MPH from the west) and plentiful sunshine, officially ending
any issues with this potent system.
-- SNOW AMOUNTS/UNCERTAINTY:
As always, even at this "zero hour", there is still some modest
uncertainty in how snow amounts play out. However, we are
calling for MOST of the CWA to end up somewhere in the 5-10"
range, which is consistent with various model guidance including
the 00Z HREF. Localized higher/lower amounts are certainly
possible too. IF any locations were to exceed 10", it would
appear most favored within some of our Nebraska counties east of
Hwy 281. IF there is any particular location most favored to
fall short of 6" (perhaps only 3-4"), it would be our extreme
southeast CWA in/near Mitchell County KS, where a combination of
precipitation taking the longest to turn to snow, along with
possible influences from the northern fringe of a mid-level dry
slot could cut into amounts. As for actual precipitation amounts
(liquid equivalent), much of the southeast 2/3rds of our CWA is
in line for 0.75-1.25", which is a SIGNIFICANT amount by Jan.
standards.
- WINDS:
Fairly high confidence in our wind forecast. Right away this
morning they are fairly light (generally only 10-15 MPH and
mainly easterly). However, as the main low pressure system
passes to our south this afternoon-evening, wind will turn more
northerly while increasing in speed (from west-to-east across
the area), with sustained speeds commonly 25-35 MPH and frequent
gusts 35-45 MPH (isolated 50 MPH possible). Obviously this could
cause plentiful issues with blowing/drifting, although with the
initial several hours of snow being on the wetter side to what
degree is somewhat in question. Between sunrise and noon
Tuesday, gusts of 30-40 MPH will remain common, but then
decreasing steadily Tuesday afternoon and allowing snow clean-up
to get into full force.
- WARNING ("headline") DECISIONS:
After some long consideration, have opted to convert roughly the
southwest half of our CWA (including the Tri Cities) from a
Winter Storm Warning to a Blizzard Warning, while letting the
Winter Storm Warning ride farther north and east. PLEASE NOTE
that true blizzard-criteria wind speeds (gusts 35+ MPH) won't
kick in until this afternoon-evening, but just went ahead and
started the Blizzard Warning this morning for simplicity sake.
Reaching official blizzard criteria is not a "sure thing", but
felt the combo of significant snow/strong winds made this
conversion warranted particularly for that part of our CWA (most
population, including parts of the I-80/Hwy 281 corridors. The
Blizzard Severity Index (BSI) is also most supportive of this
part of our CWA having the overall-WORST issues (values slightly
over 4), but please note that at least near-blizzard conditions
will likely unfold within the Winter Storm Warning area and
further conversion to Blizzard cannot be ruled out by later
shifts. As for the "end time" of the Warnings, made no change
(still 9 AM Tues), but could easily see eastern counties
possibly needing extended closer to Noon depending on blowing
snow trends.
- OTHER "MINOR" temperature details:
Made very minimal change to temperatures over the next 36 hours,
Actual highs today mainly 30-36 degrees, but temperatures will
steadily fall into the 20s and even teens this afternoon in our
west, allowing initially wetter/stickier snow to turn drier and
more prone to blowing issues. Low temps tonight mainly teens and
highs tomorrow mainly 20s, as despite sunshine returning the
fresh snow could really hold things back.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 550 AM CST Mon Jan 8 2024
- A significant winter storm will impact our entire coverage
area (CWA) to varying degrees today into tonight, with the
majority of FALLING snow occurring this morning through this
evening, but the worst impacts from blowing/drifting snow
ramping up from west-to-east this afternoon-overnight as
northerly wind gusts ramp up as high as 40-50 MPH. MOST places
now expected to pick up between 5-10" of snow.
- Roughly the southwest half of our CWA (including the Tri
Cities) has been converted to a Blizzard Warning as those
counties are overall most-favored to experience a few hours of
blizzard conditions later today-tonight as winds ramp up, but
at least near-blizzard conditions are also probable elsewhere
in our CWA where a Winter Storm Warning continues.
- Our active weather pattern continues beyond the current storm,
with a chance for a touch of light snow returning already
Wednesday, and perhaps a better chance for accumulating snow
during the Thurs-Fri time frame (uncertainty high, but does
not appear nearly as significant as current system.
- Starting especially Thursday night onward (likely into the
first part of NEXT week...beyond our current 7-day forecast),
we will need to brace for what will likely be our overall-
coldest, multiple-day stretch since the infamous Feb. 2021
cold air outbreak. Several days of single-digit high temps
appear probable, along with several overnight-morning wind
chills of at least -15 to -30 degrees (probably eventually
prompting Advisories and possible Warnings).
&&
.DISCUSSION...
Issued at 533 AM CST Mon Jan 8 2024
UP FRONT NOTE: in the interest/necessity of time, the ENTIRE
remainder of this discussion will focus solely on these next 48
hours, and particularly on the impending winter storm. The most
important items in our longer term forecast are outlined in Key
Messages above.
-- VARIOUS NOTES/ITEMS COMPLETELY RELATED TO THE IMPENDING
WINTER STORM:
- Meteorological basics/general expectations:
In the mid-upper levels, water vapor satellite imagery and short
term model data clearly depict a vigorous closed low/vort max
churning over eastern NM, with the exit region of a powerful
100+KT upper level jet streaming northeastward along its
periphery, and promoting increased lift into our area within its
left exit region. At the surface, a roughly 996 millibar low s
centered over the northeast NM/TX Panhandle border area. Out
ahead of the surface low, an impressive southerly low level jet
has resulted in impressive (for January) warm air/moisture
advection into our region, and there is even up to a few hundred
J/kg of elevated instability/CAPE noted over our KS/southern
zones, where some rain showers (possibly with some sleet) have
already developed and the possibility exists for some weak
thunderstorms.
Over the course of today, the warm air advection will steadily
be replaced by cold air advection as the nearly vertically
stacked upper/surface lows move east into northwest OK, causing
our surface/level winds to turn northerly and increase across
our CWA with time from west-to-east. Although this low pressure
track is typically a touch too far south to bring us significant
precipitation/snowfall, latest model runs have keyed in on
impressive lift/forcing/frontogenesis to the north of the main
low, with a significant expansion (explosion?) of moderate-
heavy precipitation likely to break out over the entire CWA this
morning, but the overall-heaviest amounts targeting roughly the
southeast 2/3rds of our CWA. For the vast majority of the CWA,
precipitation type will be snow (heavy at times). However
through at least mid-morning (9-10 AM) lingering warm air aloft
could keep precip type as mainly rain (and possibly sleet in
convective cores) in parts of our KS zones up toward the Hebron
area. However, even much of this area should turn to snow by
mid-late morning as the low-levels cool aided by strong dynamic
forcing/lifting processes.
This evening-tonight into Tues AM, the powerful upper
level/surface storm system will reach southern MO, with our
winds ramping up and turning more northwesterly in a tight
pressure gradient, with with snow gradually becoming lighter in
nature while ending from west-to-east. By sunrise, especially
the western 2/3rds of our CWA will be snow-free, but lingering
light snow might take closer to 9-10 AM to fully vacate our far
eastern zones. Even as falling snow exits, tonight into Tues AM,
strong north-northwest winds gusting as high as 40-50 MPH
(anything over 45 would likely be an exception) will promote
continued blowing/drifting snow issues.
Finally, Tuesday afternoon will not only bring steadily
decreasing winds (actually fairly light by sunset...only around
10 MPH from the west) and plentiful sunshine, officially ending
any issues with this potent system.
-- SNOW AMOUNTS/UNCERTAINTY:
As always, even at this "zero hour", there is still some modest
uncertainty in how snow amounts play out. However, we are
calling for MOST of the CWA to end up somewhere in the 5-10"
range, which is consistent with various model guidance including
the 00Z HREF. Localized higher/lower amounts are certainly
possible too. IF any locations were to exceed 10", it would
appear most favored within some of our Nebraska counties east of
Hwy 281. IF there is any particular location most favored to
fall short of 6" (perhaps only 3-4"), it would be our extreme
southeast CWA in/near Mitchell County KS, where a combination of
precipitation taking the longest to turn to snow, along with
possible influences from the northern fringe of a mid-level dry
slot could cut into amounts. As for actual precipitation amounts
(liquid equivalent), much of the southeast 2/3rds of our CWA is
in line for 0.75-1.25", which is a SIGNIFICANT amount by Jan.
standards.
- WINDS:
Fairly high confidence in our wind forecast. Right away this
morning they are fairly light (generally only 10-15 MPH and
mainly easterly). However, as the main low pressure system
passes to our south this afternoon-evening, wind will turn more
northerly while increasing in speed (from west-to-east across
the area), with sustained speeds commonly 25-35 MPH and frequent
gusts 35-45 MPH (isolated 50 MPH possible). Obviously this could
cause plentiful issues with blowing/drifting, although with the
initial several hours of snow being on the wetter side to what
degree is somewhat in question. Between sunrise and noon
Tuesday, gusts of 30-40 MPH will remain common, but then
decreasing steadily Tuesday afternoon and allowing snow clean-up
to get into full force.
- WARNING ("headline") DECISIONS:
After some long consideration, have opted to convert roughly the
southwest half of our CWA (including the Tri Cities) from a
Winter Storm Warning to a Blizzard Warning, while letting the
Winter Storm Warning ride farther north and east. PLEASE NOTE
that true blizzard-criteria wind speeds (gusts 35+ MPH) won't
kick in until this afternoon-evening, but just went ahead and
started the Blizzard Warning this morning for simplicity sake.
Reaching official blizzard criteria is not a "sure thing", but
felt the combo of significant snow/strong winds made this
conversion warranted particularly for that part of our CWA (most
population, including parts of the I-80/Hwy 281 corridors. The
Blizzard Severity Index (BSI) is also most supportive of this
part of our CWA having the overall-WORST issues (values slightly
over 4), but please note that at least near-blizzard conditions
will likely unfold within the Winter Storm Warning area and
further conversion to Blizzard cannot be ruled out by later
shifts. As for the "end time" of the Warnings, made no change
(still 9 AM Tues), but could easily see eastern counties
possibly needing extended closer to Noon depending on blowing
snow trends.
- OTHER "MINOR" temperature details:
Made very minimal change to temperatures over the next 36 hours,
Actual highs today mainly 30-36 degrees, but temperatures will
steadily fall into the 20s and even teens this afternoon in our
west, allowing initially wetter/stickier snow to turn drier and
more prone to blowing issues. Low temps tonight mainly teens and
highs tomorrow mainly 20s, as despite sunshine returning the
fresh snow could really hold things back.
&&
.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 606 AM CST Mon Jan 8 2024
- General overview for KGRI/KEAR:
This period will be highlighted by a fairly significant winter
storm (snow storm), that will not only promote a varied mix of
MVFR/IFR/LIFR ceiling and/or visibility the vast majority of the
time, but also dump GENERALLY around 6-10" of snow, with
increasing winds especially later this afternoon-overnight
blowing it around and causing drifting etc.
- Ceiling/visibility/snowfall details:
Although VFR ceiling could hang on for another 1-2 hours (mainly
at KGRI), there is still very high confidence that hte vast
majority of the period will be sub-VFR, with IFR likely by 15Z
or so as steadier snow starts breaking out. Have indicated a
gradual return to MVFR ceiling by later tonight into Tuesday
morning. Some guidance suggests improvement to MVFR could occur
sooner than indicated at KEAR/later at KGRI, so there is some
uncertainty. As for visibility/snowfall, light snow could break
out anytime in the next 1-2 hours, with a fairly abrupt onset of
moderate-heavy snow then likely by 15-16Z (perhaps some sleet at
the very outset?). Once the steady snow kicks in, prevailing
IFR/LIFR visibility will be common through much of the remainder
of the period (perhaps low-end MVFR later tonight as snow rates
let up and assuming blowing snow is not overly-significant).
- Winds:
The lightest winds will certainly occur during the first 6
hours, generally sustained only 10-15 KT/gusts under 20KT as
direction shifts from easterly to northeasterly. Thereafter,
stronger winds arrive this afternoon onward as direction turns
more northerly and eventually north-northwesterly, with much of
especially the latter 12-15 hours featuring sustained speeds
20-30KT/gusts 30-40KT.
&&
.CLIMATE...
Issued at 533 AM CST Mon Jan 8 2024
- DAILY PRECIPITATION/SNOWFALL RECORDS FOR JAN. 8TH ARE VERY
LIKELY TO BE BROKEN TODAY AT GRAND ISLAND/HASTINGS:
-- Grand Island (official snow measured near airport):
Current precipitation record: 0.35" in 1937
Current snowfall record: 4.0" in 1937
-- Hastings (official snow measrued at NWS office):
Current precipitation record: 0.10" in 1992/1985/1918
Current snowfall record: 3.0" in 1985
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...Blizzard Warning until 9 AM CST Tuesday for NEZ060>062-072>075-
082>085.
Winter Storm Warning until 9 AM CST Tuesday for NEZ039>041-
046>049-063-064-076-077-086-087.
KS...Blizzard Warning until 9 AM CST Tuesday for KSZ005-006-017-018.
Winter Storm Warning until 9 AM CST Tuesday for KSZ007-019.
&&
DISCUSSION...Pfannkuch
AVIATION...Pfannkuch
CLIMATE...Pfannkuch