Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/02/24
Area Forecast Discussion
National Weather Service Denver/Boulder CO
807 PM MST Mon Jan 1 2024
.KEY MESSAGES...
- Next storm system with mostly light snow expected late Thursday
through Thursday night
- Potential bigger storm by late next weekend
&&
.UPDATE...
Issued at 805 PM MST Mon Jan 1 2024
Another quiet night with no changes needed to current forecast.
Higher valleys in low lying spots have already dropped below zero
but current grids have that covered overnight.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 249 PM MST Mon Jan 1 2024
Residual moisture and a subtle shortwave, combined with sufficient
daytime heating has been enough for some shallow convection to
develop across the higher elevations... mainly the northern
Foothills. It`s difficult to say if any precipitation is reaching
the surface, especially given a very dry boundary layer noted
from surface observations and ACARS soundings.
A weak trough axis will pass through the region tonight through
Tuesday. A shallow/weak cool front is expected to move through the
region tonight. Overnight lows will generally be comparable to
last night`s, with the Grand/Jackson county cold spots once again
dipping below zero.
The aforementioned cold front will lead to high temperatures on
Tuesday 5-10F cooler than today. An initially mostly cloudy day
will see gradual clearing as moisture departs the region. With
little flow aloft, light winds are expected yet again.
.LONG TERM...(Tuesday night through Monday)
Issued at 249 PM MST Mon Jan 1 2024
A sharp ridge will shift eastward across the forecast area
Tuesday night into Wednesday, keeping dry and mild weather in the
forecast. Sunshine should abound on Wednesday per cross sections,
with most of the cirrus holding off until very late in the day or
Wednesday night. However, a weak backdoor cold front does appear
to push across the plains which could offer up some cooling
despite the sunshine. Temperatures will still average a few
degrees above normal.
By Thursday, models remain fairly consistent with the treatment
and location of the next weather system moving through the
Southern Rockies. Some models have nudged the snow slightly
northward, which means a little better chance of light snow
sneaking into Denver metro. The highest odds of snow would still
favor the mountains, and Palmer Divide area under the region of
better QG lift. The heart of QG lift should will likely stay
well south of our forecast area into far southeast Colorado and
northeast New Mexico. Although mainly light snow is expected,
slick travel can still be expected as colder temperatures will
support road snow especially by Thursday evening. Odds of snow
decrease rather quickly north of Denver so places like Fort
Collins may see only flurries or no snow at all.
Friday into Saturday will feature mostly subsidence and drying,
although another trailing shortwave and sufficient orographics
will likely bring enough support for mountain snow. Accumulations
should stay on the light side due to limited moisture.
Temperatureswill rebound to/near above normal levels late Friday
or Saturday.
Eyes will remain on the next potential storm system late next
weekend into Monday of next week. While most models and runs show
a potential low carving out in the Central Rockies, there is, and
should remain a fair amount of uncertainty with regard to depth
and intensity of this storm system. What was interesting, perhaps
even surprising, is that very few ensemble members give a
significant snowfall to the forecast area (just 4% of ECENS and
13% of GEFS have a 6" or greater snow for Denver), while the vast
majority (>80%) have just a light snowfall of 1-4". Given the
track, one would think there would be greater potential, but
we`ll continue to keep our eyes on this one should anything
change.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 449 PM MST Mon Jan 1 2024
VFR conditions thru the period. Light south winds this evening
may briefly shift to the north around 06z as a weak front moves
across. Winds will then shift back to drainage by 09z. On Tue,
light south winds will become east by 19z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...RPK
SHORT TERM...Hiris
LONG TERM...Barjenbruch
AVIATION...RPK
Area Forecast Discussion
National Weather Service Northern Indiana
643 PM EST Mon Jan 1 2024
.SYNOPSIS...
Issued at 226 PM EST Mon Jan 1 2024
Rather cloudy overnight and into Tuesday. Temperatures this week
will generally be seasonably cool, if a touch a above normal.
There is a risk of freezing drizzle Tuesday night, followed by
lake effect snow Wednesday into Thursday. Dry otherwise for
inland areas.
&&
.SHORT TERM...(This Evening through Tuesday)
Issued at 226 PM EST Mon Jan 1 2024
Key message:
*Quiet weather beneath mostly cloudy skies.
High pressure over Iowa provides quiet weather over the next 24
hours along with rather cloudy skies. A few breaks are noted, but
stratus otherwise persists from the Appalachians through the
Upper Peninsula. Clouds will provide insulation tonight resulting
in low temperatures right near normal, while providing a spring
board for slightly above-normal highs Tuesday afternoon (upper
30s.) Tonight, I did nudge temperatures up just a touch over the
in- house blend, which was too optimistic with sky cover.
Therefore, the current forecast is closer to the 75th percentile
(warmest) solutions, compared to the blend`s 50th percentile.
&&
.LONG TERM...(Tuesday Night through Monday)
Issued at 226 PM EST Mon Jan 1 2024
Key Messages:
*Freezing drizzle possible Tuesday night (low confidence in
occurrence).
*Renewed lake effect snow for northwest Indiana midweek.
High pressure slides southeast in response to an Arctic Front racing
in from the Upper Great Lakes Tuesday night. Ahead of the front, low-
level moisture becomes trapped beneath a developing inversion.
Plenty of low-level lift accompanies this tough dropping in such
that freezing drizzle is a concern Tuesday night. Forecast soundings
at this distance leave something to be desired as usual members like
the NAM are perhaps over-doing the FZDZ, while the GFS is under-
representing the risk. In coordination with GRR, I have introduced
slight chance (20%) POPs Tuesday night in northwest IN and southwest
MI. Confidence is low at this distance and is something that will
need to be scrutinized in the next two forecast cycles.
The Arctic front pushes through during the day Wednesday but has
little moisture associated with it. Therefore, it will take
several hours, but a response from Lake Michigan is expected
Wednesday night and Thursday. A first glance at soundings suggests
an elevated, dry DGZ with shallow equilibrium levels. Therefore,
significant lake effect snow seems unlikely for northwest Indiana,
but small accumulations like the past 24 hours are probable.
The long term period ends with two midlatitude cyclones passing
through the CONUS. Of course, storm tracks are woefully uncertain at
this distance. Via pattern recognition and being robbed of a descent
snow storm before, I continue to suspect the first cyclone (this
weekend) will pass to our southeast. The in-house blend says
otherwise, for the moment, warranting POPs. The second cyclone
early next week could pan out similarly. For the moment, however,
I`ll acknowledge it looks exciting.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 636 PM EST Mon Jan 1 2024
ACARS soundings from KORD and KFWA depict the story well with
drying occuring AOA 850 mb and some below 950 mb with a stout
inversion holding strong as modest WAA commences. Cigs have been
slowly falling over the past couple of hours after a brief
increase, with both locations expected to remain MVFR through at
least 12Z with slow improvement expected on Tuesday as SW flow
establishes. Cigs may continue to vary either side of 2000 ft at
KSBN.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory from 1 PM to 10 PM EST Tuesday for LMZ043-
046.
&&
$$
SYNOPSIS...Brown
SHORT TERM...Brown
LONG TERM...Brown
AVIATION...Fisher
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Area Forecast Discussion
National Weather Service Louisville KY
833 PM EST Mon Jan 1 2024
==============================================================
Key Messages:
- Very light drizzle/snow grains continue into the evening.
- Cool and partly cloudy Tuesday.
==============================================================
.Forecast Update...
Issued at 828 PM EST Mon Jan 1 2024
Minor tweaks to the forecast at this time to account for a low
chance (less than 20 percent) of sleet for the Bluegrass tonight
based on METAR, mPing and weather observer reports during the last
hour or so. Cloud top temperatures and LEX ACARS sounding show
moisture below the DGZ layer while any mesoscale or synoptic lifting
mechanism is lacking, so coverage and duration of any frozen
hydrometeors tonight will be spotty and short-lived probably related
to cloud-scale processes. Accumulations are not anticipated.
Rest of the forecast looks on track with cloudy skies for the rest
of the night and the morning as thermal trough aligns very well with
the stratus edge. Some clearing will work out from the southeast
tomorrow afternoon as deamplifying shortwave ridge and surface high
pressure approach the region. Given the cloudiness and small
advective component, a small diurnal temperature change will be in
place.
&&
.Short Term...(This evening through Tuesday)
Issued at 220 PM EST Mon Jan 1 2024
Currently... Some light echoes are moving through southern Indiana,
northern Kentucky, and the Bluegrass region this afternoon, likely
bring some very light drizzle/snow grains to the surface.
Temperatures have struggled to depart from the morning low due to
the thick low stratus deck. These conditions will continue into the
evening.
Tonight... The positively tilted trough will begin to move east out
of the region and surface high pressure will drift into the region
from the west. Low clouds will begin to thin and erode from west to
east in the early morning hours. As the high moves towards the area,
light winds will back to the southwest. Low temperatures are
expected to be in the mid-upper 20s.
Tuesday... Upper-level ridging will quickly move over the region,
and zonal flow will fill in behind. Surface high pressure will still
reside over the region, and clouds will thin. Winds will remain
light and out of the southwest. High temperatures are expected to be
in the low-mid 40s. Tuesday should be a pleasant break in between
weather systems moving through the Ohio Valley.
&&
.Long Term...(Tuesday night through Monday)
Issued at 225 PM EST Mon Jan 1 2024
=============================================================
Key Messages:
* Potential for a stronger system to affect the region this
weekend. Low confidence on track/p-type at this time.
=============================================================
A surface cold front and upper level trough will approach the region
from the west on Wednesday. Ahead of the trough, southwesterly flow
should allow temps to climb into the mid/upper 40s during the
afternoon hours, with fropa likely occurring after sunset. Appears
very little moisture will be associated with the trough and surface
front, so forecast has trended dry for this timeframe. Colder
conditions will then advect in behind the front for Thursday, but
mid-level ridging building in from the west will allow temps to
modulate some on Friday.
Forecast becomes a bit complicated and uncertain going into the
weekend. A strong southern stream trough will swing into the
southeastern U.S. and take on a negative tilt. At the surface, an
area of low pressure will develop over the Gulf of Mexico and move
into AL/GA/FL by Saturday. Strong forcing/lift in conjunction with
deeper moisture being advected poleward will result in the
development of widespread precipitation. Model guidance and their
respective ensembles still vary on the overall storm system track,
northward extent of the precipitation shield, and depth of cold air
that will be in place for the weekend, so confidence in the forecast
specifics remain low. With that said, there is potential for
impactful snow accumulations if everything comes together just
right, so this will be a system worth keeping an eye on in the
coming days.
&&
.Aviation...(00Z TAF Issuance)
Issued at 615 PM EST Mon Jan 1 2024
Impacts/Confidence:
- High confidence in MVFR ceilings through this TAF period
- Medium confidence in VFR conditions starting Tuesday afternoon.
Discussion...MVFR conditions will continue until at least early
Tuesday afternoon with gradual clearing from south to north
thereafter. Although the upper flow is more progressive, cold
temperatures aloft will continue promoting BKN-OVC stratus layer
across the region. Therefore, decided to keep MVFR ceilings through
2/18Z given climatology and model support. On the other hand,
surface high pressure over the Mid Mississippi will slowly move
towards the Tennessee Valley allowing winds to subside and back to
the southwest by Tuesday morning. VFR conditions should return by
late Tuesday afternoon but confidence in exact timing is low at the
moment.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&
$$
Update...ALL
Short Term...SRM
Long Term...DM
Aviation...ALL