Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/07/24

Area Forecast Discussion

National Weather Service Cheyenne WY

 427 PM MST Tue Feb 6 2024

.KEY MESSAGES...

- A messy storm system is expected to pass through our area
  Wednesday into Thursday, bringing accumulating mountain snowfall
  and scattered rain and snow showers for the valleys.

- Strong winds are increasingly likely on Wednesday night and
  Thursday as the storm system departs the area.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 300 PM MST Tue Feb 6 2024

A sprawling, messy storm system is slowly meandering across the west
this week, and is expected to bring more active weather over the
next few days. Currently, the axis of this trough is pushing into
the central California coast. Satellite imagery indicates a plume of
rich moisture streaming out ahead of the trough across the Four
corners states and into Wyoming/Nebraska this afternoon. The
deepening trough over the west coast is helping to amplify the
downstream ridge over the central Plains, which is supporting mild
temperatures across the area. While 700-mb temperatures are analyzed
at around +2 to +4C across the area, we aren`t quite seeing
temperatures as warm as this signal aloft indicates, likely due to
the inconsistent sunshine, snow cover, and lack of downslope wind.

Heading into tonight, the upper level low will continue to deepen
and creep eastward, leading to the flow aloft becoming increasingly
southerly. A pocket of deeper moisture shifting northward will
intersect the mountains and increase snow shower activity once again
in the Sierra Madre range. The HRRR is showing a very aggressive
solution with nearly 0.5" QPF prior to sunrise Wednesday. Though
other guidance is not as robust, increased snow slightly for the
overnight period to account for this possibility. Expect a lull, or
at least lighter snowfall rates Wednesday morning in the Sierra
Madre range in between moisture pushes. Meanwhile, a weak surface
high over the northern plains in the wake of a modest shortwave
swinging across south central Canada is expected to drop a weak back-
door cold front into portions of the High Plains tonight. The light
upslope flow and increased moisture may allow for fog to pool into
the central/northern NE Panhandle, and possibly far eastern Wyoming.
There is not enough confidence for a fog headline yet, but will
need to monitor this evening if this manages to push in.

The bulk of this next storm system finally arrives on Wednesday. The
mid-level front is likely to push through in two phases: first
Wednesday morning with an initial vort-max rotating around the main
upper level low, and second Wednesday afternoon/evening as the main
trough axis pushes through. Initial SSW flow aloft (700 to 500-mb
layer) will become more SW to WSW after the first vort-max, and then
W to WNW behind the main trough axis. Expect snow to resume in
earnest by mid afternoon in the Sierra Madre, with the potential for
fairly heavy snowfall rates through Thursday morning. Driven
somewhat by the latest Hi-Res model guidance, edged snowfall totals
up slightly for the mountains during this event, leading to enough
confidence to upgrade the existing watch to a Winter Storm Warning.
The start time was also accelerated to 06z tonight to account for
the possibility of an initial surge in moisture discussed in the
prior paragraph. While the Snowy range is expected to receive less
snow due to shadowing from the initial phase with a southerly
component, the area should do better behind the main trough axis
when winds gain a northerly component. As a result, decided to add a
Winter Weather Advisory for this zone, with a later start time.
Further east, we remain in the warm sector of this system as the
upper level low passes to the north. Cold air advection aloft behind
the first push of the mid-level front will actually lead to the
development of some modest instability over the High Plains in the
presence of a saturated middle/upper atmosphere. As a result, Hi-Res
models are showing shower activity kicking off in the afternoon
ahead of and along the second frontal push. Precipitation type will
start as rain east of I-25, but could quickly switch to snow behind
the main trough axis. A rogue rumble of thunder can`t quite be ruled
out. For the most part, QPF is limited with this activity. Northwest
flow wraps up behind the departing low-pressure system, which could
bring another round of snow into portions of the area (mainly north)
Wednesday night into Thursday AM. While some moisture wraps around
the backside here, but flow along an isentropic surface looks to be
descent rather than ascent. Northerly upslope in Converse/Carbon
county could be enough though to produce light snow accumulations.
This looks sub-advisory for now, but could need to be watched in the
future.

Lastly, the northwest flow behind this departing system may lead to
a return of the winds across southern Wyoming. While we`ve enjoyed
nearly 3 weeks without a wind headline in the core of winter,
guidance is showing the possibility for this to come to an end
Wednesday night and Thursday. GFS-based in house probabilities give
only a 40% chance of high winds over the I-80 summit, but the GFS
may actually be on the low end of guidance, which is fairly rare.
Most Hi-Res models show winds exceeding 50-knots in this area, and
the NAM shows impressive 700-mb winds exceeding 65-knots briefly
early Thursday AM. This was enough evidence to at least go for a
watch for the southern Laramie range, but would like to see a little
more inter-model consistency before expanding this to other zones,
or upgrading to a warning. There`s some uncertainty on how blow-able
the remaining snowpack will be, or if it managed to crust over
yesterday/today. Didn`t message blowing snow in the watch or in the
grids yet, but may need to watch to see if the wind will pick up
some snow after all.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 300 PM MST Tue Feb 6 2024


An unsettled pattern is expected across much of the western CONUS
late in the week through mid-week next week. Thursday evening into
Friday morning a broad 250mb trough will be positioned generally
across north central to northwestern CONUS with a strong jet across
much of the Deep South northeast into the southern Midwest. This
trough will be the first of many to propagate across the region
through the long term period, with each passing trough bringing snow
chances to the mountains and lower-elevations. This first upper-
level trough will stall slightly throughout the day Friday, with the
trough axis still over central Wyoming by Saturday morning. With
this stalled, positively tilted trough, southwesterly flow will
remain across the region Thursday evening through Saturday morning.
Westerly to southwesterly 700mb flow develops over the western CWA,
specifically over the Sierra Madre and Snowy ranges, throughout the
day as a 700mb low traverses over northern Minnesota and southern
Canada. Favorable surface flow promotes upslope development of snow
showers across the mountain ranges Thursday evening through Saturday
morning. Underneath this broad upper-level trough, cloudier skies
are expected though temperatures will be near-average for this time
of year with highs east of I-25 in the mid-30s to mid-40s and highs
in the 30s west of I-25.

As the first upper-level trough finally pushes through the region on
Saturday, precipitation chances spread across much of the CWA,
especially southern portions of the region. Westerly atmospheric
flow turns northwesterly to northerly as the western portion of the
trough begins to tilt more positively as an upper-level ridge
attempts to build over the West Coast. Northwesterly flow coupled
with strong 500mb cyclonic vorticity advection on the back side of
the trough will promoted continued lift across the region.
Additionally, an advancing cold front will further support snow
chances across much of the CWA as well as drop temperatures
significantly for Saturday. Highs on Saturday will be around 10
degrees colder area wide behind the front and with continued cloud
cover over the region associated with the upper-level trough,
surface warming will be significantly reduced throughout the day.

Sunday will be a transition day across much of the area as an upper-
level ridge attempts to build in from the west, only to be forced
south and away by a digging upper-level trough over southern Canada
and an incoming shortwave off the coast. As the upper-level ridge
and digging upper-level trough interact, height gradients will
tighten across much of Wyoming, increasing atmospheric winds just
northeast of the CWA. Despite the northeasterly displacement, height
gradients over the CWA will strengthen just enough to promote
enhanced winds across the wind prone region of southeast Wyoming.
Craig to Casper gradients increase to the mid-40s for Sunday evening
into Monday morning, further supporting elevated winds across the
wind prone regions. High winds do not look likely at this time due
to the lack of 700mb jet support across the region, but elevated
winds look likely at this time. Snow chances look to be confined to
the mountains for Sunday, with minimal accumulation at this time.
Temperatures will be slightly warmer than Saturday, due to
downsloping winds across the Laramie Range.

The remaining long term forecast remains just as unsettled as
another upper-level trough pushes into and across the region Monday
through Wednesday morning. Disagreement remains between the ECMWF
and the GFS as to the exact progression of this upper-level trough
for early next week. Significant differences exist between the long
range models at the 700mb level, with the GFS suggesting
northwesterly flow associated with a trough across southern Canada
while the ECMWF keeps relatively zonal flow across most of the
western CONUS. Kept low PoPs in for the mountains for this time
period as enough lift exists for slight chances of snow across the
mountain ranges through Monday through Wednesday. Gradual warming
trend expected Sunday onward, with near-average temperatures once
again by Tuesday.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 418 PM MST Tue Feb 6 2024

Some changes to the aviation forecast, with upslope flow
increasing fog potentials for the Nebraska Panhandle late this
evening into the morning hours tomorrow. Confidence has
continued to increase, with the latest HRRR model analysis
indicting IFR conditons for KBFF, KAIA, KSNY, and KCDR. As a
result, went ahead and dropped ceilings and visibility for all
terminals in the Nebraska Panhandle through the late morning
hours. Into tomorrow, approaching cold front continues to track
across the CWA, bringing widespread rain and snow showers from
west to east. For areas east of the I-25 corridor should remain
as rain to rain/snow mix throughout the afternoon before
switching to all snow when the temperatures drop below freezing
in the overnight hours.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Storm Warning from 11 PM this evening to 5 PM MST
     Thursday for WYZ112.
     Winter Weather Advisory from 11 AM Wednesday to 5 PM MST
     Thursday for WYZ114.
     High Wind Watch from Wednesday evening through Thursday
     afternoon for WYZ116.
NE...None.

&&

$$

SHORT TERM...MN
LONG TERM...AM
AVIATION...MRD



Area Forecast Discussion

National Weather Service Quad Cities IA IL

 939 PM CST Tue Feb 6 2024

.KEY MESSAGES...

- Areas of fog expected tonight, becoming locally dense east and
  northeast of the Quad Cities where a Dense Fog Advisory is in
  effect.

- Above average temperatures will continue through the week.
  Record warm low temperatures are possible Wednesday night and
  Thursday night, with near record high temperatures possible on
  Wednesday and Thursday.

- Rain showers are likely on Thursday into Thursday night with some
  thunder possible ahead of a frontal system.

&&

.UPDATE...
Issued at 930 PM CST Tue Feb 6 2024

Issued a Dense Fog Advisory to the east and northeast of the
Quad Cities through 9 AM Wednesday. GOES nighttime microphysics
imagery showed fog and low stratus slowly advecting into eastern
counties (from the east) and surface observations have already
fallen to a half mile or lower in these areas. With high
pressure over the Mid Mississippi and Ohio Valley region, winds
will remain light overnight allowing air temperatures to hold
near the dewpoint. Therefore expect the fog to expand slightly
to the west through midnight before gradually lifting northward
into early Wednesday AM as SSE winds steadily increase. It`s
possible the advisory may have to be expanded to the NW;
however, the duration of dense fog should be more limited on the
western fringe per the latest HRRR runs.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 227 PM CST Tue Feb 6 2024

Tonight...As high pressure slides off to the east, south to
southeasterly LLVL return flow will maintain along with passing
cirrus streaks. This would hopefully keep the temps from bottoming
out well below guidance like the last few nights, but will still
undercut the loaded blend a few degrees. Lighter sfc flow to the
east in lingering stratocu fields and earlier fog bank acrs northern
IL may be the spawning grounds for more fog development this evening
after sunset. Then the southeasterly LLVl flow may advect it back
north and northwestward acrs portions of northwest IL again
overnight. An uncertain scenario as fog is many times, but will
place patchy to areas of fog mention in these eastern areas. If this
fog/low stratus occurs, freezing fog on some untreated sfc`s will
again be a factor.

Wednesday...Fcst soundings suggest 25-30 KT southwesterly low level
jet(LLJ) to really carve out a pronounced dry wedge/inversion aloft.
Even limited mixing depth into the base of this inversion will
produce highs in the low to mid 50s, with several areas in the
west/southwest reaching the upper 50s to near 60. Near record
territory for several climate sites, as long as any nocturnal
stratus doesn`t take all day to mix out.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Issued at 227 PM CST Tue Feb 6 2024

Wednesday night...An increasingly breezy and seasonably mild night,
and feel most developing showers will hold off until after sunrise
Thursday.

Thursday...A taste of mid April with warm sector highs in the upper
50s to mid 60s, again if cloud cover and prefrontal WAA-type showers
arn`t too heavy in coverage. A rather vigorous sfc low still on
track to progress acrs the northern plains, with a SHREF timed
frontal passage through the area by late Thu night. Pre-frontal
pressure gradient to drive southerly wind gusts 35 to near 40
MPH if the currently indicated top of the mixed layer is
realized. Sctrd rain showers at times during the day and into
the evening, before a likely dry slot whirls in acrs the local
area after midnight. Elevated MUCAPEs of 100-200+ and a plume of
6.5 to 7 C/km mid layer lapse rates support some thunder from
mid morning through the evening, before shunting off to the east
later Thu night. An unseasonable PWAT feed by warm and more
moist pre- frontal conveyor of 0.70 to 0.80 inches will fuel
passing downpours, but speed of the elements may limit rainfall
amounts to a tenth to quarter inch for most spots.

Friday and Saturday...Post-frontal regime and cooling this end of
week period, but still above normal temps into Saturday. Will have
to watch for post-wave wrap around precip possibly skirting acrs the
northern CWA Friday into Saturday, but most precip ensembles suggest
this activity to remain to the north of the area. Highs Saturday
down in the upper 30s north, to the mid 40s south.

Sunday through Monday...Latest ensemble blends and upper jet trends
have trended with a split flow blocking pattern into early next
week, with the southern stream becoming the dominant and energized
flow. Thus with the local fcst area looking to largely to remain in-
between these active streams, it`s appearing to be dry into
Tuesday.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 548 PM CST Tue Feb 6 2024

Main concern overnight into early Wednesday AM is for a period
of fog and low stratus near DBQ. Confidence remains low on the
extent and severity of the fog, which could become locally dense
near and east of DBQ. Otherwise, anticipate prevailing VFR
through the period at all the terminals and increasing SSE winds
on Wednesday.

&&

.CLIMATE...
Issued at 205 PM CST Sun Feb 4 2024

Record High Temperatures:

February 7:
CID: 57/1987
DBQ: 51/1882
MLI: 59/2009
BRL: 66/2009

February 8:
CID: 57/1925
DBQ: 55/1925
MLI: 63/1990
BRL: 66/1990

February 9:
DBQ: 51/2009

Record Warm Low Temperatures:

February 7:
KDBQ: 39/1878

February 8:
KDBQ: 37/1938
KMLI: 40/1925

February 9:Thursday.
KDBQ: 42/1966
KMLI: 43/1966

February 10:
KDBQ: 37/1886
KMLI: 39/1903

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...Dense Fog Advisory until 9 AM CST Wednesday for ILZ001-002-007-
     009-016>018.
MO...None.

&&

$$

UPDATE...Uttech
SHORT TERM...12
LONG TERM...12
AVIATION...Uttech
CLIMATE...12



Area Forecast Discussion

National Weather Service Goodland KS

 229 PM MST Tue Feb 6 2024

.KEY MESSAGES...

- Strong SSW winds (30-45 mph gusting 55 mph) will create
  hazard travel conditions during the day on Wednesday. Reduced
  visibilities associated with blowing dust possible, mainly in
  far western Kansas.

- Low confidence in accumulating snow this weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 110 PM MST Tue Feb 6 2024

Synoptic Overview: An upper level ridge presently situated over
the central CONUS will shift east toward the Mississippi River
Valley tonight and Wed.. as a large upper level low (presently
centered along the central California coast) progresses
inland/eastward across the Intermountain West.

Tonight: A low-level southerly return flow regime will be
established in earnest overnight.. as the aforementioned ridge
shifts east of the High Plains and upstream height falls
/strengthening SW flow atop the Rockies/ foster the development
of an increasingly pronounced lee trough/cyclone in Colorado.
Southerly winds will increase to 20-30 mph late this evening and
overnight.. as the MSLP-H85 height gradient tightens on the
eastern periphery of the deepening lee cyclone. The thick veil
of cirrus presently shrouding the region will persist
overnight.. in assoc/w a continued influx of upper level
moisture via strengthening SW flow aloft.

Wed-Wed night: Strong SSW winds are anticipated across the
majority of the area during the late morning and afternoon.. as
the MSLP-H85 height gradient further tightens on the eastern
periphery of the [still] deepening lee cyclone in northeast
Colorado. Guidance continues to indicate that widespread upper
level cloud cover will shift eastward into central KS during the
day.. and that unimpeded insolation will aid in the development
of a rather deep (6-8 KFT AGL) mixed-layer by mid-afternoon.
GFS forecast soundings suggest that 35-50 knot southerly (SSW-
SW) low-level flow will be present within/throughout the
deepening mixed-layer, strongest along/east of Highway 25 in
northwest Kansas.. on the eastern periphery of the eastward
advancing lee cyclone.. where the MSLP-H85 height gradient will
be tightest. With the above in mind, expect sustained SSW-SW
winds on the order of 30-45 mph and gusts up to 60 mph..
windiest (overall) along and east of Highway 25 where stronger
low-level flow (on the eastern periphery of the aforementioned
lee cyclone) will more favorably overlap with peak heating/
mixing. Reductions in visibility assoc/w blowing dust are
possible over portions of western KS, though.. saturated ground
conditions associated with recent rainfall and snow-melt are apt
to be a significant limiting/mitigating factor. Either way,
strong S to SW winds will create hazardous travel conditions
across the majority of the area, especially on west-east routes
such as I-70, where cross winds will be strongest.

Guidance continues to suggest that unimpeded insolation may
yield ~250 J/kg of MLCAPE over portions of eastern CO and far
western KS at peak heating.. indicating a potential for high-
based, low-topped convection (lifted condensation level ~8 KFT,
equilibrium level ~22 KFT) in the ~21-00Z time frame. Simulated
reflectivity forecasts via the 18Z HRRR and NAM NEST suggest
that scattered convection may develop invof a surface to 850 mb
trough /low-level convergence zone/ in southeast Colorado at
peak heating. Lightning is a possibility.. especially if forcing
happens to be augmented by well-timed DPVA attendant small
amplitude waves in SW-SSW flow aloft. While locally strong winds
may accompany any low-topped convection.. the magnitude of said
winds would likely be similar to /indistinguishable-from/
already breezy background flow.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 229 PM MST Tue Feb 6 2024

On Thursday, a cold front is expected to move southeast across the
area bringing some weak chances, less than 25%, for light rain and
perhaps some light snow for those mainly west of the Colorado
border. Latest guidance has backed off from yesterday`s forecast
with a dry slot developing over portions of the Southern Plains
between the two systems. Little to no snow accumulation is expected
should any snow develop Thursday night. Weak shortwaves ahead of the
large trough moving over the Western CONUS and moisture moving
across the Rockies overnight Thursday through Friday morning is
expected to bring more chances (less than 40%) for rain and light
snow along and west of the Colorado border. Little to no
accumulation is expected given the above freezing temperatures
currently forecast. Friday evening, a surface low is expected to
develop and move southeast towards the Kansas/Oklahoma border,
continuing the chances for light snow through the overnight hours.

Over the weekend, precipitation chances are expected to continue as
more moisture moves over the Rockies. Light snow is the current
forecasted precip type, though above freezing temperatures may lead
to more light rain occurring over the eastern half of the area
as the precipitation expands east. The best chance for any
accumulations is on Saturday with PoPs up to 60%, while more
widespread snow chances look to occur during the day on Sunday.
It`s still a little too far out for amounts to be discussed;
however, we are looking at a wet heavy snow for most of the area
with snow to liquid ratios ranging from 7-12:1. There remains a
decent amount of uncertainty for how deep the trough becomes as
well as how quickly the system moves over the Rockies, leading
to some guidance leaving the area dry. Continue to monitor the
forecast over the next few days as we gather more information
about the upcoming system. High pressure over the Rockies will
lead to dry conditions on Monday.

Temperatures look to be above normal on Thursday with highs in the
50s to around 60 degrees and overnight lows in the 20s to lower 30s.
Friday will be slightly cooler with highs in the upper 40s to lower
50s. Overnight lows are forecast to fall into the 20s Friday night.
Over the weekend, highs are expected to be in the mid 30s to mid 40s
both days with overnight lows in the upper teens to mid 20s. Monday
is expected to warm up slightly during the day with highs in the 40s
to around 50 degrees and overnight lows in the upper teens to lower
20s overnight.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 159 PM MST Tue Feb 6 2024

GLD: VFR conditions will prevail through the TAF period.. with
ceilings confined to cirrus at or above 18 KFT AGL. South winds
at 12-17 knots this afternoon will increase to 20-30 knots this
evening and persist overnight.. as the MSLP gradient tightens
on the eastern periphery of a deepening lee cyclone in northeast
Colorado. South winds will further strengthen to 30-40 knots
several hours after sunrise Wednesday (15-18 UTC) and persist
through the afternoon. A ~50 knot southerly low level jet (LLJ)
may foster a period of LLWS at ~1,000 ft AGL early Wednesday
morning (~07-14 UTC), though -- some degree of mixing (as one
might infer from the presence of breezy/gusty surface winds) --
may tend to decrease LLWS magnitude and impact, especially in
the presence of a unidirectional wind profile.

MCK: VFR conditions are anticipated to prevail through the TAF
period, with ceilings confined to cirrus at or above 18 KFT AGL.
S winds at 10-15 knots this afternoon will increase to 15-25
knots late this evening/overnight.. as the MSLP gradient
tightens on the eastern periphery of a deepening lee cyclone in
northeast Colorado. South winds will further strengthen to 30-40
knots several hours after sunrise Wednesday (15-18 UTC) and
persist through the afternoon. A ~50 knot southerly low level
jet (LLJ) will foster a period of LLWS at ~1,500 ft AGL early
Wednesday morning (~07-14 UTC).. until surface winds
substantially increase (a few hours after sunrise).

&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...None.
CO...None.
NE...None.

&&

$$

SHORT TERM...BV
LONG TERM...KMK
AVIATION...BV



Area Forecast Discussion...Updated

National Weather Service Lincoln IL

 937 PM CST Tue Feb 6 2024

.KEY MESSAGES...

- Areas of fog tonight through mid morning Wednesday, 40-60%
  chance of 1/4 mile visibility.

- Unseasonably warm temperatures Wednesday through Friday with
  highs in the 50s and 60s.

- South to southwest winds gusting 35-45 mph Thursday afternoon,
  posing difficult travel for high profile vehicles.

- Low chance (20%) for scattered thunderstorms Thursday evening.

&&

.UPDATE...
Issued at 937 PM CST Tue Feb 6 2024

Forecast is needing some updating tonight as dense fog is now
expanding to the west across the CWA. Initial look at the HiRes
models showed the dense fog would be moving to the west, however,
that does not seem the case at this time. High clouds are blocking
the view of the lower clouds/fog over central IL, but trends that
were seen before the high clouds moved in showed the dense fog and
lower clouds were just expanding to the west. Therefore, an update
to the forecast was needed to expand the fog in the grids and to
issue a Dense Fog Advisory. Where temps are below freezing the
rest of the night...and there is fog...this fog will be freezing
fog and could cause some icy spots on untreated surfaces and
roads. Update should be coming shortly.

Auten

&&

.DISCUSSION...
Issued at 230 PM CST Tue Feb 6 2024

Areas of dense fog had lifted by midday, leaving an area of low
stratus stretched north to south through the central CWA early
this afternoon. Midday sun is doing its best to punch holes in the
thin cloud deck while also eroding it from the edges, so most
areas will see mostly sunny skies by sunset. However, all the
parameters that contributed to dense fog last night remain in
play tonight with the surface ridge axis draped over the area and
lingering low level moisture. We will see increasing cirrus from
the west tonight which could act to limit the extent/duration of
dense fog, so will hold off on headlines with this forecast
package. Will mention the possibility of dense fog overnight
through mid morning in messaging (wx story graphics/HWO)
particularly north of a Canton to Mattoon line, in line with
latest RAP/HRRR guidance (HREF shows 40-60% probabilities of 1/4
mile visibility in these areas 03-14z). Lows are forecast in the
lower 30s, so patchy slick spots could develop where the dense fog
overlaps sub- freezing roads.

By midday Wednesday the synoptic pattern begins a major shift as
an upper level ridge axis pushes east, opening the area up to an
increasing southwest gradient flow ahead of Plains low pressure.
This brings a breezy/warmer/springlike airmass overhead for the
remainder of the work week, with highs in the 50s Wednesday, and
mid 50s to lower 60s Thu-Fri. This is a few degrees below record
highs which are in the mid/upper 60s for most areas. South to
southwest wind gusts peak Thursday afternoon when the tightening
gradient and deeper mixing bring 35-45 mph gusts down to the
surface. An area of warm advection showers ahead of an eastward
pressing cold front overspreads the region Thursday
afternoon/evening. Moisture return is limited and kept PoPs in the
30-40% range with light QPF near/under a tenth inch. A period of
elevated instability (200-400 J/kg MUCAPEs) slides east over the
northern half of the CWA Thursday evening, so will keep mention of
isolated thunder in the forecast. Will need to watch this
timeframe for a few gusty showers/storms that could bring 40-50 kt
winds at 2-3k feet down to the surface. The cold front pushes
across the region Friday afternoon/overnight, and have another
mention of low chance PoPs near/south of I-70 Friday night when
the next upper wave rides along the boundary. Instability is even
lower for this round of showers so we don`t have a thunder
mention.

A more seasonable airmass filters across the Midwest behind
Friday`s frontal passage, with highs mainly in the 40s through
early next week. An active southern steam jet will be in place
through the extended. Most ensemble guidance keeps precip south
of the area late this weekend and early next week, though the
blended guidance shows slight chance PoPs (15-20%) for the
southern half of the CWA.

25

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 552 PM CST Tue Feb 6 2024

Another complicated TAF forecast for the night and into tomorrow.
MVFR conditions are expected at all sites this evening, but IFR
clouds and lower vis are expected this evening at BMI and DEC, but
looks like will advect westward this evening into the overnight
hours...based on HRRR HiRes model guidance and satellite loop.
With this being an advection setup up, CMI will not have the lower
cigs, but should get some light fog later tonight through
overnight. All other sites will see vis drop to below 1sm with PIA
and BMI seeing 1/2sm fg. The lower cigs and vis will last into the
morning hours and be slow to improve at BMI with VFR conditions
not expected until around noon. Winds will be light tonight but
then become more southeast overnight and then southerly tomorrow
late morning into the afternoon.

Auten

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 11 AM CST Wednesday for ILZ027>031-
036>038-041>043-048-051>053.

&&

$$