Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/09/24
Area Forecast Discussion
National Weather Service La Crosse WI
505 PM CST Mon Jan 8 2024
.KEY MESSAGES...
- A more significant winter storm is still expected across the
area tonight through Tuesday evening/night, with the most
impact in northeast Iowa and southwest Wisconsin. Snow amounts
were increased there into the 9-14" range. Lesser amounts are
expected northwest. Drifting snow in 30-40 mph gusts will
increase the impacts Tuesday. Commuting on Tuesday will be
affected areawide.
- Forecast confidence has increased on a fast-moving, light snow
producing system for later Wednesday afternoon and night.
- Another accumulating snow system may affect the area later in
the week with a return to colder winter-like temperatures.
&&
.DISCUSSION...
Issued at 310 PM CST Mon Jan 8 2024
Current radar and surface observations show a broad
precipitation shield heading toward the area with ~0.05" of
water per hour reported (0.5" snow). The leading edge is now
into Des Moines with light snow. The surface low is forecast to
track northeast from its current location east of Amarillo TX,
to near Chicago by mid-afternoon Tuesday.
The storm has remained fairly on track with previous forecasts.
Snow amounts have been increased somewhat across far northeast
Iowa and into southwest and central Wisconsin with a period of
1-2" per hour rates expected and around an inch or slightly over
of liquid. 08.12Z SPC HREF probabilities for 12+" are 20-30%
and mainly confined to southwest WI and far northeast IA south
of Highway 18. The latest RAP runs are now suggesting a bent
back surface low structure which would act to prolong the snow
duration across that higher impact area. Instability will also
reign south of La Crosse with upright and slantwise instability
suggested across many CAMs above the 600-700 mb frontogenesis
zone later night and Tuesday morning. As the cyclone deepens and
the deformation maximizes in the morning, would think some
convective rates are certainly possible to 3" per hour. The
centered ensemble 50% is about 9 to 14" in southwest WI and
Clayton/Fayette counties in IA...and the forecast was bumped a
bit to be in that range. Winds will increase Tuesday with gusts
in the 30-40 mph range expected in this same heavy snow
region...thus it will be dangerous with heavy snow, low
visibilities, and then drifting expected. The highest snowfall
rate period will be Tuesday morning centered around the morning
commute. Some power outages may occur, although the snow ratios
dont suggest a heavy wet snow.
Further northwest of this "ideal" snowfall area, lesser amounts
are forecast as instability wains and the main deformation
band(s) is likely further south. Thus, a decreasing snow amount
forecast northwest, with northcentral WI / Taylor county will
be on the edge with 1-3" expected. Have converted the Winter
Storm Watch to an Advisory for 2-6 inches of snow northwest of
an Albert Lea MN to Wausau WI. Winds will add to the impacts in
the Advisory with drifting expected, albeit less.
The snow should generally shift east Tuesday, possibly out of
the Advisory area by 6 pm, with lingering snow, and the double
structure surface low suggesting the south could snow into the
evening. Will need to reassess the Advisory and Warning end
times as this storm progresses.
Wednesday Night Light Snow Accumulations Now Likely
A swift moving system will bring a period of good lift across
the area later in the afternoon Wednesday and Wednesday night.
There are still some differences on the track and intensity of
this system, but the forecast snow chances were increased with a
light snow expected of about an inch. This is a fairly quick
moving system, but does have moderate QG convergence, with the
only question of track of the stronger lift. At this time, most
areas should remain below 1" total /08.00Z Grand Ensemble
suggesting 30% chances for 1+"/. Impacts may come into MN/IA
for the afternoon commute on Wednesday.
More Accumulating Snow Chances and Colder Temperatures Suggested
By Week`s End
Another accumulating snow system looks to move through the area
Friday and Saturday with the seasons coldest air behind it. The
western CONUS trough ejects east through the ArkLaTex, and then
northeast toward the eastern Great Lakes as longwave trough
deepening occurs as the flow consolidates over North America.
The 08.00Z ECMWF/Canadian/GEFS ensembles suggest, for now, the
highest probability for heavy snow would be south of the area,
with 30-50% chances /highest in swrn WI/ of 2" or more. Maybe
the biggest story will be the very different cold air mass
behind. The blended solutions (NBM) suggest wind chills of -15
to -25 Sunday morning in a brisk northwest wind. Depth and
timing of the trough as well as a secondary shortwave trough
from the northwest are still of lower confidence with spread in
this outcome quite large in the ensembles. Confidence is higher
on the larger ideas of snow possible and a return to more
winter- like cold.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 505 PM CST Mon Jan 8 2024
CIGS: clouds will continue to lower as snow overspreads the area
this evening, if LIFR/IFR persisting into Tue afternoon. Cigs will
start to improve overnight Tue as winter storm continues to exit
east. Could break back into VFR on Wed before more low clouds
quickly return ahead of the next upper level weather system Wed
evening.
WX/vsby: expect IFR snows to move in this evening, and could drop
into LIFR from time to time. With the expectation for at least a few
inches of snow, BLSN will be an issue at KRST. However, wet nature
of the snow may result in more drifting rather than blowing/vsby
impacts. Most of the snow looks to push east of KRST by 00z Thu,
then KLSE before 06z.
WINDS: easterly winds will turn northerly toward 12z Tue, become
strong/gusty by late morning. Gusts up to 30 kts expected.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Warning from midnight tonight to 6 AM CST
Wednesday for WIZ041>044-053>055-061.
Winter Weather Advisory from midnight tonight to 6 AM CST
Wednesday for WIZ029-032>034.
MN...Winter Storm Warning from midnight tonight to 6 AM CST
Wednesday for MNZ095-096.
Winter Weather Advisory from midnight tonight to 6 AM CST
Wednesday for MNZ079-086>088-094.
IA...Winter Storm Warning from 6 PM this evening to 6 AM CST
Wednesday for IAZ008-018-019-029.
Winter Storm Warning from midnight tonight to 6 AM CST
Wednesday for IAZ009>011-030.
&&
$$
DISCUSSION...Baumgardt
AVIATION.....Rieck
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1021 PM EST Mon Jan 8 2024
.SYNOPSIS...
A strong low pressure system will impact the area tonight into
Tuesday, with heavy rainfall and very windy conditions expected
across the region. Dry weather will return Wednesday and Thursday,
before the next storm system arrives for the weekend.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 955 pm EST Monday: Regional radars show the first band of
moderate to heavy rainfall lifting northeast across northern Georgia
and PoP trends have been accelerated for the next few hours. Pockets
of observed subfreezing wet bulb temperatures persist in and near
the Blue Ridge mountains, and points immediately east, so the winter
weather advisory for freezing rain accumulations still looks well
placed. We are also beginnning to see ridge top gusts picking up,
with the latest RAP solution showing the arrival of the 60 to 70 kt
low-level jet by midnight. The NC and GA mountain wind products are
already in effect and this also looks well-timed, with the Wind
Advisory for the rest of the area picking up mid-morning Tuesday. No
changes to the hazard headlines appear needed late this evening.
Otherwise, water vapor imagery shows the deep, closed upper low
spinning over Oklahoma late this evening. This highly dynamic upper
low will feed abundant Gulf moisture into the region tonight through
Tuesday, with precipitable water values likely running around 200
percent of normal for this time of year. A strong core of 50+ kts is
evident on model profiles at 2 to 3 kft over the region. A High Wind
Warning remains in effect for the NC mountains abv 3500 ft, with a
wind advisory for elevations below 3500 feet thru 00z Wed. A Wind
Advisory also takes effect Tue morning through Tue afternoon east of
the mountains given the stout jet just off the surface. This will
pose a threat with any degree of mixing. Given the wet soil
conditions, these winds will have the potential to knock down trees
and cause power outages and structural damage through Tue afternoon.
There will be significant hydro issues beginning toward daybreak as
moderate to high rainfall rates aided by stg forcing trains and
slowly crosses east over the area. Several main stem rivers are
fcst/d to reach flood levels, many area streams will likely reach or
exceed bankfull. Urban flooding is likely. The existing flood watch
covers all but the southern-most tier of the forecast area, and this
still seems reasonable given flood guidance values.
Thunderstorms developing in a blossoming warm sector from the
southeast will bring a threat of both higher rainfall rates and the
potential for severe thunderstorms. A few hundered J/kg of SBCAPE
may be uncovered as updraft helicity bands develop mainly southeast
of I-85 mid morning through Tuesday afternoon. Strong to severe
convective winds are possible in this area, and a few brief
tornadoes are not out of the question. Temperatures will remain
around or a little abv normal overnight, while highs Tue reach abv
normal due to increasing s/ly flow.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
As of 210 pm EST Monday: Forcing and deeper moisture will be pulling
away from the forecast area to start the short term period, with
generally token chance PoPs advertised across mainly eastern
portions of the CWA Tue evening. The only exception will be an
enhanced (i.e., 50-60%) chance along the TN/NC border, where a W/NW
cold advection acting on lingering low level/wrap-around moisture
from the TN Valley into the crest of the Appalachians. Backed low
level flow (more W than NW) and generally unfavorable thermodynamic
profiles will limit the potential for accumulating snow showers.
(Except in localized areas where the topography is oriented more
N->S than NE->SW. e.g., western Graham County). Overall, this looks
to be another sub-Advisory snow shower event. Surface winds will
otherwise remain quite strong and gusty from the W/SW through Tue
night, gradually abating through the daylight hours Wed.
The remainder of the short term will see a much-welcomed drying
trend with cool conditions. Temps will generally be below climo
through the period, other than perhaps a brief above-normal
excursion for Thursday`s maxes.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
As of 220 pm EST Monday: Global models are in quite good agreement
regarding the overall pattern and even many of the details of the
extended period. The axis of a broad long wave trough will remain
centered across the central Conus early in the medium range, with a
continued very active pattern across the entire country. The period
will begin dry and seasonably cool before the next blockbuster/
strengthening storm system lifts out of Texas and the southern Great
Plains on Friday. Associated forcing and moisture may begin
impacting the western Carolinas and northeast GA as early as Friday
morning. This timing will be important, as sufficient cold air may
remain in place across the mountains to support a brief period of a
wintry mix Fri morning.
Otherwise, confidence is quite high that another round of widespread
rain with embedded thunderstorms will sweep across the region Friday
into Friday night. While the track of synoptic surface features will
actually be quite similar to tomorrow`s system, the global models
generally agree that the intensity of the features will be weaker,
while the overall pattern will be a little more progressive. If this
pans out, rainfall amounts and winds associated with the late week
system...while still noteworthy...will be less impressive. Having
said that, guidance is also suggesting perhaps less of a potential
for in-situ cold air damming and more potential for a warm sector/
weakly unstable air mass to make significant inroads into the CWA.
This would indicate perhaps a higher potential for severe storms.
Meanwhile, despite the expected (hopefully) lesser rainfall amounts,
poor antecedent hydro conditions lingering from the early week storm
will yield some degree of an excessive rainfall/localized flooding
threat. Temperatures are expected to begin the period with
near-to-above normal temperatures before cooler-than-normal
conditions become established in the wake of Friday`s storm
system.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
At KCLT and elsewhere: Conditions will rapidly deteriorate from the
southwest overnight as deeper moisture arrive quickly ahead of the
advancing low pressure system to the west. MVFR bases have already
arrived at the Upstate TAF sites late this evening and these will
develop across NC through 07Z. IFR cigs will shortly follow
thereafter in the developing heavier rainfall rates. Expect liquid
precipitation at the TAF sites, although temperatures near KAVL
could get locked in just above the freezing mark through daybreak,
and brief ZR cannot be ruled out. Confidence is too low to mention
any wintry types there at present, however. Otherwise, Anticipate
LIFR cigs and IFR visibility as the heaviest rain moves in through
the morning hours. Will introduce thunder potential mainly from KAND
to KCLT with the lifting wedge frontal boundary from late morning
through late afternoon, but some rumbles of thunder are also
possible in the rest of the Upstate and at KHKY. Winds will increase
through the period, with gusts above 30 kt likely at all sites, and
possibly above 40 kt at times. Will also feature LLWS midday Tuesday
given the stout jet just a few hundred feet off the ground.
Conditions are unlikely to improve until just beyond the current
period.
Outlook: Drying is expected Wednesday through Thursday before
another storm system begins to impact the area Friday into the
weekend.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Wind Advisory until 7 PM EST Tuesday for GAZ010-017.
Flood Watch through Tuesday evening for GAZ010-017-018-026-028.
Wind Advisory from 10 AM to 10 PM EST Tuesday for GAZ018-026-
028-029.
NC...Wind Advisory until 7 PM EST Tuesday for NCZ048>053-058-059-
062>065.
Flood Watch through Tuesday evening for NCZ033-035-049-050-052-
053-056-059-062>065-068>070-501>510.
Wind Advisory from 10 AM to 10 PM EST Tuesday for NCZ035>037-
056-057-068>072-082-501>510.
High Wind Warning until 7 PM EST Tuesday for NCZ033-048>052-
058-059.
Winter Weather Advisory until 7 AM EST Tuesday for NCZ033-049-
050-053-063>065-501-503-505-507-509.
Flood Watch from 7 AM EST Tuesday through Tuesday evening for
NCZ036-037-057-071-072-082.
SC...Flood Watch through Tuesday evening for SCZ008-010-101>109.
Wind Advisory from 10 AM to 10 PM EST Tuesday for SCZ008>014-
019-101>109.
Flood Watch from 7 AM EST Tuesday through Tuesday evening for
SCZ009-013-014.
&&
$$
SYNOPSIS...JDL
NEAR TERM...HG/SBK
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...HG
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
822 PM CST Mon Jan 8 2024
.UPDATE...
Issued at 822 PM CST Mon Jan 8 2024
National CONUS GOES-16 water vapor imagery this evening is a
sight to behold, with a tightly wound-up low pressure center in
southern Oklahoma and an impressively expansive cloud shield
extending from the southern Louisiana Coast into southern
Ontario. Regional radar imagery is similarly impressive with a
large shield of precipitation across the mid Mississippi River
Valley associated with the warm conveyor belt of the developing
cyclone and a burgeoning deformation band across the Plains.
In all, the forecast appears to be in good shape with an initial
band of precipitation (associated with 700-500mb fgen) now lifting
toward US-24 and a much broader region of WAA-driven precipitation
lifting into central Illinois. Webcams beneath the initial band
of precipitation show primarily rain thus far, though with time,
snow should begin to mix in and become dominant, especially as
the band lifts further northward.
Taking a quick peek at incoming 00Z guidance, I am concerned
that our advertised snow totals areawide through the duration of
the storm are too high. For one, the rain/snow line looks like it
will stall somewhere near or just west of I-355 and north of I-80
tomorrow afternoon, leading to a stark reduction in snow totals
over the core of the Chicago metropolitan area. More specifically,
conditions may vary markedly from west to east across Will,
DuPage, and the northern section of Cook counties from tomorrow
morning onward. As has been highlighted for several days, exactly
where the rain/snow line stalls will make or break the forecast
and define the sharp snowfall gradient. Secondly, snow ratios
through the entire event may struggle to exceed 7:1 or 8:1, with
Cobb output applied to the fresh 00Z HRRR suggesting even lower
ratios near 6:1. For this reason, would not be surprised if
observed snow totals end up on the lower side of advertised ranges
during both rounds of snow. Even so, the very (extremely?) wet
nature to the snow will no doubt lead to difficult to dangerous
travel conditions, with the impact levels still looking
appropriate in each respective headline area (Winter Storm
Warning/Winter Weather Advisory).
Updated products will be sent soon.
Borchardt
&&
.SHORT TERM...
Issued at 225 PM CST Mon Jan 8 2024
Through Tuesday night...
* Snow, heavy at times, will overspread the forecast area between
about 8 pm and midnight. Vast majority of snowfall expected
within about a 3-6 hour window. Snowfall rates will likely reach
1 inch per hour in some areas and could approach 2 inches/hour,
particularly with any embedded convective elements.
* Winter storm warning will be issued for Lake, Kane, LaSalle
Counties westward. Winter weather advisories will be in effect
tonight into tomorrow morning remainder of northeast Illinois
and northwest Indiana.
* Snow, heavy at times, is expected to continue northern portions
of the area through much of the day Tuesday, though possibly
mixed with or changing to rain near the lake.
Headlines:
Have opted to upgrade to a winter storm warning for northwestern
1/3 to 1/2 of the CWA, roughly northwest of a line from Streator
to Aurora to Waukegan. Guidance has trended toward shorter break
in the precip intensity early Tues AM, so for the sake of
simplicity have converted the advisory for tonight to just a
warning for the duration of the storm.
No changes have been made to the winter weather advisory tonight
into tomorrow morning for most of the remainder of the CWA. We still
expect a quick hitting burst of snow tonight, with snow likely to
mix with then change to rain from south to north for areas
roughly south of I-80 very late tonight into Tuesday morning.
We have also extended northern Cook and DuPage Counties winter
weather advisory into tomorrow evening. Potentially very sharp
gradient in snow is expected to set up from the lakefront to
western Dupage and far northwestern Cook Counties. Confidence in
how much, if any, of the western portions of these counties will
reach warning criteria is too low to justify a warning at this
time, but may need to be considered in later forecast updates.
Tonight:
Warm conveyor belt with deepening cyclone will move across the
area, driven by very deep and strong isentropic ascent. Strong
upper level divergence from some coupling of jet streaks will
combine with the strong warm air advection to result in very
strong, deep upward vertical velocities tonight. The strong low
level jet will transport unusually moist air mass for this time of
year northward with PWATs of 0.70-0.85" or roughly 200%+ of
normal. In addition, guidance does show some transient f-gen
bands, which could locally enhance precipitation rates and
possibly even allow for an isolated thunderstorm or two. There is
a very small chance for lightning (<10%), but chances appear
small enough to keep out of the forecast. Whether or not there is
lightning, the convective elements could result in snowfall rates
of 1" to possibly locally 2" per hours.
Forecast soundings show a pretty classic archetype for big fat
(1"+ diameter) aggregate snowflakes tonight with deep isothermal
layer hovering just below 0C, along with deep ascent above that
layer promoting variety of flake types. Air temps are forecast to
be above freezing at the onset of the snow, with wet-bulbing and
dynamic cooling likely knocking temps down to around 32. Given the
marginal air temperatures and likely very wet nature of the
snowfall, would expect low snow to liquid ratios. The dense,
heavy nature of the snow will make shoveling challenging and could
lead to snow sticking to tree limbs and even traffic lights.
The strong warm air advection should eventually overcome the
dynamic cooling to push the rain snow line into our southern CWA
(south of US Highway 24) overnight with the rain snow line likely
continuing to march northward, possibly reaching as far north as
the I-80 corridor by or just after sunrise.
Tuesday:
As the warm conveyor belt will shift east of the area late
tonight/early Tuesday morning, should see a bit of a lull in the
heavier precipitation rates. However, a tongue of very moist air
should wrap west across our area to the north of the mid level
low. Strong DCVA and divergence should result in continued precip
development Tuesday morning, especially central and northern CWA.
As this is taking place, the rain snow line should continue
translating north to around the I-55 corridor. In addition, there
will probably be just enough lake warming of the already
marginally cold air to flip areas near the lake over to rain or
rain snow mix Tuesday morning. The rain snow line should hold
relative steady during the afternoon. Guidance has trended a bit
farther south with the WSW to ENE east oriented deformation band,
which looks to set up across the northern half of our CWA late
morning. That deformation band should inch northward with the
heaviest precip rates north of I-80 and especially north of
I-88/290 during the afternoon.
Precip type in this band should be most wet, heavy snow, except
closer to Lake Michigan where a rain or rain/snow mix is expected.
Given the magnitude of forcing and at least transient bands of
f-gen, we could see rates approach 1" per hour at times, even with
the very low SLRs. This could result in snowfall totals across the
warning area pretty commonly in the 5-9" range, with some local
10"+ totals not out of the question. This will be a very heavy,
wet snow. Air temps near freezing could reduce the impact on
travel conditions outside of the heavier bursts of snow, but
amounts expected to be this high and given the wet nature of the
snow, felt a warning was certainly justified.
Tuesday evening:
Snowfall will taper off from west to east, though an additional
inch or so of snow could fall across many areas before snow ends.
The bigger story Tuesday evening will be the quickly increasing
winds. Strong pressure rises and modest cold air advection should
keep boundary layer mixed enough to transport down some 30-40 mph
gusts. While the wet nature of the snow should limit the
blowing/drifting threat some, the wet snow sticking to tree limbs
and traffic lights, etc could become problematic as the strong
winds develop.
-Izzi
&&
.LONG TERM...
Issued at 306 PM CST Mon Jan 8 2024
Wednesday through Monday...
Key Messages:
- A quick hit of light snow Wednesday night/early Thursday
morning, possibly impacting Thursday morning commute along and
north of I-80.
- Likelihood continues to increase that another significant winter
storm will impact at least portions of the region Friday into
Saturday.
- Coldest air so far this season expected this weekend into early
next week, with subzero wind chills.
A very active winter weather pattern is expected to persist across
the central CONUS later this week into the weekend. Within this
active pattern, a compact and fast moving low will track eastward
from the Mid-Missouri Valley into the Western Great Lakes late
Wednesday into Wednesday night. As it does so, about a 5 to 9 hour
period of light accumulating snow (generally an inch or less) is
likely (60-70% chance) Wednesday night, primarily for locations
along and north of I-80. Temperatures will be below freezing
during this period of snow, so while it will be light, some
patchy slick travel conditions may persist into the early Thursday
morning commute. The snow is expected to abate by, or slightly
after daybreak Thursday, with the remainder of the day looking
quiet.
Thereafter, attention continues to focus on the increasing
likelihood for another significant winter storm to track east-
northeastward from the southern Plains late Thursday into the
Ohio Valley region sometime late Friday into Friday night. While
ensemble guidance continues to depict some spread with the actual
track of this system, the general consensus at this time tends to
favor a track southeast of Tuesday`s winter storm. For this
reason, the threat of accumulating snowfall (potentially of
several inches in some locations) could end up favoring most of
northern IL into northwestern IN Friday into Friday night. We will
continue to keep a close eye on the evolution and track of this
system, as the potential for accumulating snow in combination with
strong north-northwest winds (gusting in excess of 35 mph) could
support some higher end impacts in or near the region into Friday
night.
Beyond this storm, conditions continue to favor a turn towards a
much colder period of weather from Sunday into next week. In fact,
high temperatures by for Sunday and Monday of next week are
currently forecast to only be in the single digits to low teens,
with subzero overnight low temperatures and wind chills.
KJB
&&
.AVIATION...
For the 00Z TAFs...
Aviation forecast concerns for the current TAF period include:
* Snow arriving this evening and falling at a moderate to heavy
rate overnight
* Precipitation type forecast for the daytime hours tomorrow: all
snow expected at RFD; mainly rain/drizzle favored at MDW and
GYY; rain and snow both likely at times at ORD and DPA with low
confidence in the precise timing of each precipitation type
* Precipitation type transitioning to all snow again at all TAF
sites for tomorrow evening
* LIFR/IFR ceilings and visibilities expected through most of the
precipitation event
* Blustery easterly winds tonight into tomorrow morning; blustery
northwesterly winds tomorrow evening
This TAF period is a busy one, to say the least. Precipitation
associated with a deepening low pressure system centered over
Oklahoma at press time will spread over the terminals this evening
and continue through the remainder of the TAF period while the
low`s center tracks towards and into the Chicago metro. While a
few raindrops can`t be ruled out initially at the onset of
precipitation this evening, precipitation should otherwise reach
the ground as all snow tonight, likely falling at a pretty good
clip at times overnight into tomorrow morning with snowfall rates
likely to at least briefly reach 3/4"-1" per hour. This will
likely translate to at least temporary LIFR visibilities amidst
prevailing low-end IFR or LIFR ceilings.
Around or soon after daybreak tomorrow, the precipitation type
forecast becomes a bit trickier for the Chicago metro terminals,
particularly ORD and DPA. With the low pressure system`s dry slot
moving overhead and surface temperatures expected to warm ever so
slightly, precipitation is likely to transition to all rain or
drizzle at MDW and GYY, while ORD and DPA are favored to see rain
at least mix in with the ongoing snow. The precipitation type
forecast for ORD and DPA is one of low confidence given that the
rain/snow line will likely end up being positioned near or over
both sites for much of the day, so have a prevailing -RASN mention
going in both TAFs for a a good chunk of the morning and
afternoon. Regardless of the exact precipitation type that falls,
IFR to LIFR ceilings and visibilities are likely to be observed
through much of this time at all four of the Chicago metro
terminals. Precipitation should change over to all snow once
again on the backside of the system tomorrow evening. Meanwhile,
all snow is expected all day tomorrow at Rockford with a second
round of moderate to heavy snowfall rates and likely LIFR
visibilities expected during the late morning and afternoon hours
there. If precipitation were to become all snow during this time
at DPA and ORD, then these heavier snowfall rates and lower
visibilities would likely be observed there as well, though this
a relatively low confidence outcome at this time (more so at ORD
than DPA).
Lastly, winds will initially be out of the east tonight, becoming
increasingly blustrier as the surface pressure gradient tightens
in response to the approach of the deepening low pressure system.
As the low`s center moves into or near the Chicago metro tomorrow,
wind directions at the Chicago metro terminals could become a bit
squirrelly, though wind magnitudes will subside at this time. On
the backside of the surface low, winds will become northwesterly
and become blustery once again with 20-30+ kt gusts expected
towards the end of the current 30-hour TAF period for ORD and MDW.
Ogorek
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Winter Storm Warning...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019 until midnight Wednesday.
Winter Weather Advisory...ILZ013-ILZ103 until midnight Wednesday.
Winter Weather Advisory...ILZ020-ILZ021-ILZ023-ILZ032-ILZ104-
ILZ105-ILZ106-ILZ107-ILZ108 until noon Tuesday.
Winter Weather Advisory...ILZ033-ILZ039 until 9 AM Tuesday.
IN...Winter Weather Advisory...INZ001-INZ002 until noon Tuesday.
Winter Weather Advisory...INZ010-INZ011-INZ019 until 9 AM
Tuesday.
LM...Gale Warning...IL and IN nearshore waters...9 PM Tuesday to 6 AM
Wednesday.
Small Craft Advisory...IL nearshore waters until 6 PM Tuesday.
Small Craft Advisory...IN nearshore waters...midnight Tuesday to
3 PM Tuesday.
&&
$$
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Area Forecast Discussion
National Weather Service Lubbock TX
527 PM CST Mon Jan 8 2024
...New AVIATION...
.UPDATE...
Issued at 406 PM CST Mon Jan 8 2024
Only some minor updates were made to the grids to add blowing snow
in the southwestern Texas Panhandle and an upgrade to a blizzard
warning. Conditions have continued to deteriorate in the SW Texas
Panhandle through the afternoon and is expected to continue for
the next several hours. A trowal was noted in the latest RAP
guidance around the 290 theta-e surface and is expected to weaken
after 00Z this evening. Across the northwestern and central South
Plains, where snow was more spotty, snust (blowing snow and
blowing dust) could mix together.
&&
.SHORT TERM...
(This evening through Tuesday)
Issued at 157 PM CST Mon Jan 8 2024
A strong storm system continues to move eastward across the Texas
Panhandle toward western Oklahoma this afternoon. The forecast
remains on track with wind issues the primary concern and snow a
secondary one. Wind speeds across the western Panhandle have reached
high wind criteria with 3-hour surface pressure rises of 2-4 mb.
Those pressure rises are progged to increase to around 5-7 mb per
three hours and expand southward. NBM and MOS both showing potential
for high wind speeds north and northeast of Lubbock through the
evening hours in the wake of the Canadian cold front moving
southeastward through the region. Have upgraded roughly the
northeastern half of the Wind Advisory to a High Wind Warning.
Regarding snowfall, models had the southward extent of meaningful
snowfall pegged well. Obs and radar show a snowband extending from
Clovis northeastward through Hereford and extending back as far
north as Tucumcari and Dalhart. A webcam at Friona has been showing
persistently heavier snowfall during the last hour with grassy
surfaces becoming covered. Higher reflectivity rates slipping
southward suggest a quick one or two inches in Parmer and Castro
counties is possible (possibly as much as three in northwestern
Parmer) before lift wanes behind the departing mid level
circulation. Have issued a Winter Weather Advisory for those two
counties into early evening to account for accumulation on area
roadways pending further cooling behind the Canadian cold front.
With the storm system pulling farther away from the forecast area
later tonight, think timing of the decrease in winds below
warning/advisory criteria looks reasonable, although breezy to windy
conditions will linger through the night and Tuesday morning before
finally diminishing later tomorrow. The strong cold advection
tonight will result in cold temperatures in line with NBM and MOS
for both tonight and Tuesday.
&&
.LONG TERM...
(Tuesday night through next Sunday)
Issued at 157 PM CST Mon Jan 8 2024
Upper troughing and cold fronts will dominate much of the forecast
through the next week. The upper low affecting the region today will
move into the Midwest by tomorrow evening while upper flow becomes
more west to west-northwesterly over the FA. The upper flow will
remain relatively unchanged through the day Wednesday, but a surface
trough associated with an upper shortwave pushing across the Central
and Northern Plains will dig southward and provide us with another
breezy day Wednesday. Winds will be out of the west at 20-30 mph.
Zonal upper flow will give way to an amplifying and quick moving
upper trough late Thursday afternoon, and the trough axis will move
through the region Thursday night into early Friday morning. Another
cold front will push into the region before midnight. Models
continue to lower precip chances associated with the system. Any
precip, mostly in the form of snow, would be limited to the Texas
Panhandle and northward. Northwesterly upper flow will dominate the
region through Saturday and will help to keep temps in the 40s and
50s. This will be followed by another quick moving upper trough on
Sunday that will bring another shot of cold air into the region that
will likely keep temps in the 30s across much of the FA Monday. This
system, similar to the one expected this Thursday, will likely be
dry in terms of precip.
&&
.AVIATION...
(00Z TAFS)
Issued at 518 PM CST Mon Jan 8 2024
A powerful storm system will continue to affect the area for the
next 24 hours. Periods of snow will affect the KPVW terminal for
the next few hours before snow tapers off. Conditions may
periodically dip into IFR but will mostly remain in MVFR during
the next few hours. Otherwise, very strong northwest winds will
persist through the overnight hours. Winds will begin to taper off
around daybreak Tuesday morning and decrease through the day.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 2 AM CST Tuesday for TXZ021-027-028-033>035-
038>044.
Blizzard Warning until 8 PM CST this evening for TXZ021-022.
High Wind Warning until 2 AM CST Tuesday for TXZ022>026-029>032-
036-037.
Winter Weather Advisory until 8 PM CST this evening for TXZ023-
027>029.
&&
$$
SHORT TERM...01
LONG TERM....51
AVIATION...01
Area Forecast Discussion
National Weather Service Tallahassee FL
1054 PM EST Mon Jan 8 2024
...New MESOSCALE UPDATE, MARINE, HYDROLOGY...
.MESOSCALE UPDATE FOR A POTENTIALLY SIGNIFICANT SEVERE WEATHER
EVENT OVERNIGHT THROUGH TUESDAY...
Issued at 1021 PM EST Mon Jan 82024
Late-evening GOES 1-min satellite imagery shows a deepening
surface low over LA strongly forced by its parent upper low
evident near the ArkLaTex region. Immediately ahead of this
feature is an extensive area of robust convection spreading into
the MS Valley. To its south is a warm front nearing the East-
Central Gulf Coast with a trailing cold front stretching along
coastal TX. A tight pressure gradient is contributing to a potent
southerly LLJ up to around 60 kts, per latest SPC mesoanalysis.
Such an intense wind field is allowing for very robust inland
moisture advection off the Gulf, which will steadily juice up the
airmass for severe thunderstorms. Latest hi-res guidance such as
the RAP shows a tongue of MLCAPE of 500-1500 J/kg translating east
towards the the western FL Panhandle and southern AL overnight.
That amount of instability overlapping a highly sheared
environment spells trouble.
Radar shows a squall line taking shape north of New Orleans and
widely scattered showers & thunderstorms downstream of it. Much of
this activity is poised to consolidate into a more potent QLCS
while moving eastward overnight. We will have to closely monitor
discrete to semi-discrete cells ahead of the line for rotation, as
some are likely to acquire supercell characteristics and pose a
nocturnal tornado threat. For these reasons, in coordination with
SPC, a Tornado Watch was issued through 12Z for our SE AL and the
FL Panhandle counties. Strong tornadoes are possible, so please
ensure you have a way to be awoken by any warnings issued.
Elsewhere expect mostly rain showers with some embedded thunder,
though winds are expected to start really picking up after
midnight. A 6Z balloon launch is forthcoming to sample the
atmosphere.
&&
.SYNOPSIS...
Issued at 355 PM EST Mon Jan 8 2024
A significant weather event is still expected tonight into Tuesday
across the area with multiple hazards. Key Messages below:
1. Strong to severe storms will begin late tonight in the form of
isolated supercells, followed by an intense squall line during the
day Tuesday. Damaging to destructive winds, tornadoes (some strong),
and hail are all possible threats.
2. Heavy rainfall is also expected with this system tonight and
Tuesday. Some flooding is possible, as well as rises to near flood
stage on some area rivers.
3. Very strong non-thunderstorm gradient winds are expected with
this system. Wind gusts of 40-55 mph are possible across the area on
Tuesday. Given wet soils, this could result in trees falling more
easily. Even higher wind gusts approaching 60 mph are expected along
the coast from Wakulla county westward to Walton County.
4. Extremely dangerous beach and boating conditions are expected.
Gales and storm-force wind gusts are expected tonight and Tuesday.
Very high surf and deadly rip currents are expected.
5. Minor to moderate coastal flooding is expected on Tuesday, most
likely along the shores of Apalachee Bay.
&&
.NEAR TERM...
(Through Tuesday)
Issued at 355 PM EST Mon Jan 8 2024
Overall, there is little change to the previous forecast.
A high-impact weather event will affect the region tonight and
Tuesday. Multiple hazards are expected, including a significant
outbreak of severe thunderstorms. Stay weather aware over the next
24 hours.
A deepening low pressure center will turn northeast across the Mid-
Mississippi Valley tonight. A large field of intense pressure
gradients and wind will engulf the trailing cold front, which will
quickly sweep east across our region on Tuesday.
In advance of the front, an extremely strong 65-80 knot southerly
low-level jet will develop tonight to our west, then translate east
across the area during the course of Tuesday morning. Strong,
damaging gradient winds are expected by late tonight into Tuesday,
with inland wind gusts around 50 mph. Along the beaches gusts of 55
to 60 mph are forecast.
The low-level jet will push a warm front northward this evening,
leading a rapid influx of maritime tropical air, with surface
temperatures and dewpoints rising during the night. The air mass
will become weakly to moderately unstable, which is bad news in
light of extreme kinematics. With the warm sector late tonight,
discrete supercells could move in from the Gulf across the
Panhandle, possibly reaching southeast Alabama. Any of these
discrete supercells could produce a strong tornado, particularly
where the air mass is most unstable and least inhibited at the
coast.
Then the cold front will blast through during the day on Tuesday,
accompanied by a solid squall line that could bring widespread
severe convective wind gusts. A few embedded tornadoes will likely
accompany the line, and these could also be strong. The latest SPC
outlook maintains the Enhanced Risk area (Level 3 of 5) over our
entire area. The squall line should exit east of I-75 and east of
the Suwannee during the late afternoon.
&&
.SHORT TERM...
(Tuesday night through Friday night)
Issued at 355 PM EST Mon Jan 8 2024
In the wake of the squall line, improving weather Tuesday night,
with breezy conditions as west winds gust around 20 mph. A dry
period of weather with light winds is expected on Wednesday and
Thursday for any post storm clean-up efforts. A couple of chilly
nights are on tap with lows ranging from the low 30s northwest
to low 40s southeast on both Tuesday and Wednesday nights, which
is a concern for those that may be without power due to Tuesday`s
severe weather. The wind chill/apparent temps Tuesday night will
make it feel like the mid 20s northwest to mid 30s southeast.
The next system takes aim at the region on Friday, with increasing
clouds in advance expected on Thursday. SPC already has much of
the region in a day 5 (Friday) 15% probability for severe weather,
which is equivalent to a slight risk in the day 1-3 time frame.
Mid-level shortwave is modeled to go negatively tilted as it swings
through the TN Valley, placing the strongest forcing for ascent
northwest of the region. The wind field may be more unidirectional,
but strong nonetheless, with deep layer bulk shear approaching
70 kts and a low-level jet over 50 knots. This will be more than
sufficient to advect a warm and unstable air mass northward, with
ensemble mean CAPE around 500 J/kg. This supports the potential
for another severe weather event with damaging winds and a risk of
tornadoes centered on Friday.
&&
.LONG TERM...
(Saturday through Monday)
Issued at 355 PM EST Mon Jan 8 2024
In the wake of Friday`s storm system, cyclonic flow aloft pulls
away from the region on Saturday, with zonal flow through early
next week. No major impactful weather expected at this time.
&&
.AVIATION...
(00Z TAFS)
Issued at 648 PM EST Mon Jan 8 2024
Gusty winds, low cigs, and LLWS remain the primary concerns
tonight. Thunder is kept at ECP/DHN given evening radar trends
showing elevated convection. The main update to the 0Z TAF cycle
was introducing TEMPO groups of +TSRA at all terminals for the
severe squall line plowing thru the region tmrw. Latest HRRR
narrows down timing: 13-15Z ECP/DHN, 14-16Z TLH/ABY, and 16-18Z
VLD. Gusts of 45+ kts are likely. Improving wx from W-to-E in the
line`s wake, but gusty winds linger.
&&
.MARINE...
Issued at 1021 PM EST Mon Jan 8 2024
The Orange Beach Buoy (42012) was reporting sustained SE winds of
25 kts with gusts near gale force and 11-ft seas late this
evening while Buoy 42036 was reporting similar conditions.
From the CWF Synopsis...A very deep low pressure center will
continue crossing the Mid- Mississippi Valley late tonight, and a
trailing cold front and pre-frontal convection will cross the
northeast Gulf waters on Tuesday. Conditions deteriorate further
as the pressure gradient tightens more, culminating in frequent
storm- force gusts in the southerlies preceding the front.
Westerly gales will kick in behind the front, lasting into early
Tuesday night. In addition, a squall line of severe thunderstorms
with tornadic waterspouts will cross the waters on Tuesday.
Conditions will gradually improve on Wednesday, and a high
pressure center will quickly pass across the waters on Wednesday
night. Southeast breezes will freshen in advance of the next storm
system on Thursday and especially Friday, with a period of gale-
force wind gusts possible.
&&
.FIRE WEATHER...
Issued at 355 PM EST Mon Jan 8 2024
Heavy wetting rains are expected tonight through Tuesday as a
strong storm system moves through the region. In particular, a
line of severe thunderstorms is expected to sweep through the
entire region on Tuesday from the early morning into the early
afternoon with the potential for large hail, several tornadoes,
and wind gusts up to 80 mph. Ahead of this line, a period of
strong winds is expected with wind gusts around 40 to 50 mph
inland and 50 to 60 mph closer to the coast. Looking ahead, dry
weather is forecast on Wednesday and Thursday, with a potential
for low dispersions on Thursday across much of the region.
&&
.HYDROLOGY...
Issued at 1021 PM EST Mon Jan 8 2024
River forecast evening update: A Flood Warning is now in effect
for the Choctawhatchee River - Newton, which is now forecast to
reach minor flood stage Tuesday afternoon, then crest by
Wednesday morning. The Pea River - Ariton is also forecast to
minor flood stage, but given that significant rainfall has not
occurred yet and that the stage change is just outside of 24 hrs,
we decided to hold off on issuing a warning and wait more cycle.
An incredible synoptic setup with a very dynamic system is expected
to begin impacting the region this evening through Tuesday.
Overall, rainfall amounts have increased slightly in the western
half of the region, owing to an initial widespread stratiform rain
event, then turning convective prior to the arrival of a squall
line. As a result, this is why rainfall amounts mainly west of the
ACF basin have trended upward. Fortunately, this area has received
less rainfall than other portions of our forecast area, so while 3-6
inches of rain does present a localized flash flood threat and will
lead to noteworthy rises on the Choc/Pea system in South Alabama, a
significant flash flood threat does not appear likely, thus no flood
watch is needed.
The squall line will deliver a very quick 1-2 inches, but its fast
progression will limit any flash flood concerns, even in the eastern
portions of the forecast area that are much more saturated. Even so,
we`ll still see modest rises on our mainstem rivers.
So while riverine and flash flood impacts are minor, the more
pressing concern is the coastal flood impacts. While timing of the
onshore winds is important, the magnitude and duration of the winds
combined with attendant winds from the squall line set up a scenario
where moderate flooding is likely in Apalachee Bay, especially east
of Carrabelle. It`s east of Carrabelle where the synoptic scale
winds of 40-50 mph with higher gusts will pile water into the bay
ahead of the squall line. Even if the squall line arrives around
16z, 2 hours prior to high tide, the additional influence of the
squall line will push water levels to warning criteria from
Carrabelle eastward. Unfortunately, the squall line timing and
environmental winds are forecast to peak as they near the
Taylor/Dixie County coast around 18z, which is when high tide
occurs. Both deterministic and ensemble guidance suggest at least 2-
4 feet AGL with isolated pockets of inundation as much as 5 feet.
While this is on the high side of the guidance, the environmental
winds are well beyond 90th percentile, so favoring the higher end
guidance seems appropriate here.
Thus a coastal flood warning was issued for Franklin County
eastward. A coastal flood advisory was issued for the Panhandle
counties to account for the strong winds leading to minor flooding
there.
We`ll watch the next system on Friday for additional rains and see
how it will undoubtedly impact our river systems into the coming
weekend.
&&
.SPOTTER INFORMATION STATEMENT...
Spotter activation is requested. Spotters should safely report
significant weather conditions and/or damage by calling the
office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 54 68 38 56 / 90 100 10 0
Panama City 56 66 40 55 / 90 100 0 0
Dothan 51 64 34 52 / 100 100 0 0
Albany 53 66 36 52 / 100 100 10 0
Valdosta 55 70 38 54 / 90 100 20 0
Cross City 59 72 42 58 / 40 100 40 0
Apalachicola 60 67 42 56 / 80 100 0 0
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...Wind Advisory until noon CST Tuesday for FLZ007>010.
Wind Advisory until 5 PM EST /4 PM CST/ Tuesday for FLZ011>017-
026-027-118.
Wind Advisory from 4 AM to 5 PM EST Tuesday for FLZ018-019-028-
029-034.
High Rip Current Risk through late Wednesday night for FLZ108-
112-114-115.
High Wind Warning until 1 PM EST /noon CST/ Tuesday for FLZ108-
112-114-115-127.
High Surf Warning until 11 AM EST /10 AM CST/ Wednesday for
FLZ108-112-114.
Coastal Flood Advisory until 1 AM EST /midnight CST/ Wednesday
for FLZ108-112-114.
High Surf Advisory until 10 PM EST Tuesday for FLZ115.
Coastal Flood Warning from 7 AM Tuesday to 1 AM EST Wednesday
for FLZ115-118-127.
Wind Advisory until midnight EST Tuesday night for FLZ128-134.
Coastal Flood Warning from 7 AM Tuesday to 7 AM EST Wednesday
for FLZ128-134.
GA...Wind Advisory until 1 PM EST Tuesday for GAZ120.
Wind Advisory until 5 PM EST Tuesday for GAZ121>131-142>146-
155>158.
Wind Advisory from 4 AM to 5 PM EST Tuesday for GAZ147-148-
159>161.
AL...Wind Advisory until noon CST Tuesday for ALZ065>069.
GM...Gale Warning until midnight EST Tuesday night for GMZ730-765.
Storm Warning until 1 PM EST /noon CST/ Tuesday for GMZ750-752-
755-770-772-775.
&&
$$
MESOSCALE UPDATE...IG3
NEAR TERM...DVD
SHORT TERM...LF
LONG TERM....LF
AVIATION...IG3
MARINE...LF/IG3
FIRE WEATHER...LF
HYDROLOGY...Godsey/IG3