Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/03/24
Area Forecast Discussion
National Weather Service Dodge City KS
516 PM CST Tue Jan 2 2024
...Updated Aviation...
.KEY MESSAGES...
- Quiet weather tonight through Wednesday Night, but a back-door
front will likely bring in widespread fog late Wednesday Night
into Thursday.
- Storm #1: Minor impact snow event likely Thursday Night into
early Friday afternoon. Probability of 2"+ snowfall in the 50
to 65% range across much of southwest Kansas. Peak snowfall
potential (10th percentile) around 4".
- A second storm early next week shows potential for widespread
Moderate or greater impacts (30-40% chance) with accumulating
snow, colder temperatures, and much stronger north winds than
Storm #1.
&&
.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 354 PM CST Tue Jan 2 2024
Late this afternoon, our southwest Kansas region found itself in a
modest northwest flow pattern aloft with benign sensible weather
conditions. A low-amplitude storm system centered across Southwest
Texas will remain well to our south with no impacts across our area.
A weak cold front pushed south leading to a north-northeast wind 12-
18 mph today, but these north winds will decrease by sunset leading
to light and variable winds tonight into the day Wednesday.
One thing the incoming swing shift and mid shift will need to
monitor is radiation fog development across our eastern counties
from roughly Hays down to Stafford... and perhaps as far west as
Dodge City by daybreak Wednesday. The HRRR continues to show
expanding one-quarter mile visibility across this region of our
forecast area. The official forecast will call for patchy fog but
not quite as far west as Dodge City. Any fog in the early morning
hours will dissipate by mid-morning as direct insolation increases.
850mb temperatures in the +3 to +5C range, along with low level
westerly wind will support afternoon highs 50F or slightly above.
Wednesday afternoon will be the last of temperatures this warm for
awhile, as a backdoor cold front at the surface will bring in slight
cold air advection along with upslope component to the low level
wind. Surface dewpoints will not decrease much, if at all, behind
the surface cold front, and this will lead to development of
widespread fog, possibly dense. The 12Z and now 18Z runs of the HRRR
that go out to 48 hours are matching what the NAM12 is showing
regarding widespread 1/4 mile visibility across much of Kansas. The
conceptual model certainly fits for widespread fog and a headline-
worthy dense fog episode is increasing in confidence. Low level
upslope, slight cold advection, fog much of the day and/or low
stratus will all prevent any appreciable warm-up on Thursday. On
this forecast cycle we will be going with upper 30s most areas for
highs based on some of the latest information coming in today, this
is going to be too high. By late afternoon Thursday, the first of
the two storms will be encroaching on far southwest Kansas, which is
discussed further in the Long Term section.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 354 PM CST Tue Jan 2 2024
This Long Term section will discuss two winter storm systems to
impact our southwest Kansas region.
Storm #1: Thursday Night and Friday... The Big Three global
deterministic models have now locked in on a 548 decameter 500mb low
centered around ABQ 18Z Thursday with an impressive cyclonically
curved jet max at the base of the low from southern Arizona into
West Texas. This setup puts southwest Kansas in favorable left-exit
region of the jet for enhanced upward vertical motion and low level
development. A large area of precipitation will develop across West
Texas into far southwest Kansas Thursday evening which will
spread/expand north into west central and southwest Kansas through
Thursday Night. Using the classical 850mb temperature field for the
rain-snow line proxy in southwest Kansas (around -1.0C for Dodge
City in January), most of our southwest Kansas region will be snow
per the ECMWF, GFS, and Canadian GDPS...all of which show around -1
to -1.5C at 06Z, which is around the time precipitation will likely
start accumulating, if not just before then. The GFS is warmest of
the three by 12Z Friday, which would support cold rain, but this
appears to be an outlier when you look at ensemble probability of
type fields from the Super Ensemble system (of the ~90% probPrecip
at 12Z Friday for Dodge City: ~60% probSnow vs. 30% probRain). The
upshot is that for most of southwest Kansas for Storm #1, the precip
type is likely to be snow for the large majority of the event.
Latest collaborated QPF forecast from WPC is showing 0.3 to 0.6" for
much of southwest Kansas (higher farther south toward OK border),
which will support a widespread fairly confident 2 to 4" snowfall
total across our region.
From an impacts standpoint, Storm #1 will likely be Minor to locally
Moderate with only small parts of our area at risk of 5+ inches of
snow (only 10% chance or less at any one location), and winds with
Storm #1 will be very manageable with easterly wind gradually
shifting to northeast then north at 10 to 15 mph at most. Surface
temperatures will also likely be right around 32F for much of the
event as well, and this will help prevent many roads from dropping
below the air temperature. Of course, higher snowfall rates during
the event will likely lead to at least some accumulation on roads.
Accumulating snow is likely to end by early Friday afternoon.
Storm #2: Late Sunday Night Through Monday Night... This storm has
the potential to have significant impacts across Kansas, including
perhaps Southwest Kansas, however there remains tremendous
uncertainty regarding when this storm will mature and where it will
undergo robust development. Both of these large uncertainties will
go into whether we receive any accumulating snow at all...or a
major, high end event leading to blizzard conditions...because as of
today...pretty much everything is still on the table. The best
forecast is still from the Super Ensemble Means. The reason ensemble
systems are very important is because we typically do not see major
day-to-day fluctuations in the Super Ensemble (Ensembles of GFS
(GEFS), Canadian (GEPS), and European (EPS). From today`s 12Z run,
Super Ensemble means are showing a surface low track from West Texas
across Oklahoma into Arkansas. Indications are this storm will have
a large areal extent with robust "comma head" of precipitation into
the cold sector across the Central Plains should mid level
cyclogenesis undergo rapid development across the Southern
Plains/Red River Valley. There is high confidence of very strong
north winds behind the developing low, such that even if we get 1-2"
of snow, widespread moderate impacts would be likely due to
significant blowing and drifting snow.
Today`s 12Z run of the popular deterministic ECMWF model now shows a
faster moving open trough, not undergoing development until the
system is well southeast of southwest Kansas, keeping southwest
Kansas dry. As of the writing of this discussion, the 12Z
deterministic ECMWF run is an outlier of not only its own ensemble
system but the other two ensemble systems as well. Regardless, Storm
#2 early next week still shows signals of
widespread moderate to major impacts should it develop faster and
move across the Great Plains slower. This will allow abundant
moisture/precipitation to overspread the cold sector across the
Central Plains along with 25 to 40 mph north winds. Keep checking
back regarding Storm #2`s potential impacts, as this forecast will
likely be in flux until all the models and their ensemble systems
really begin to lock in to a scenario we feel confident in.
&&
.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 502 PM CST Tue Jan 2 2024
Clear skies and light winds will create favorable conditions for
fog and/or stratus late tonight/early Wednesday morning. 18z
HREF and then latest CAMS continue to focus the best chances
for low clouds below 3000ft AGL and/or visibility <2miles in fog
(30-50%) being in the Hays area and east of highway 183.
Elsewhere VFR conditions are expected but would not be surprised
a brief period of patchy MVFR visibilties developing around
daybreak at Dodge City, Garden City and Libearl but confidence
is less than 10% so will not include this in the 00z TAFS. What
early morning fog/stratus that does develop will erode by 15z
Wednesday.
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Burgert
Area Forecast Discussion
National Weather Service Duluth MN
906 PM CST Tue Jan 2 2024
.KEY MESSAGES...
- Snow showers this evening and overnight especially north and
east of Duluth will cause snow accumulations under an inch
except a couple inches expected along the South Shore snow
belt in Iron County.
- Near-zero overnight low temperatures are expected Wednesday
night in northeast Minnesota, with single digit above zero in
northwest Wisconsin.
- Weak systems may pass over the Northland this weekend and into
early next weekend to bring light snowfall to the area.
&&
.UPDATE...
Issued at 859 PM CST Tue Jan 2 2024
Numerous reports of freezing drizzle across the northern MN have
begun rolling in. Satellite and surface observations indicate
ceilings are continuing to lower aiding in producing the
freezing drizzle. RAP soundings are keeping the signal for the
dry air in the mid levels and increased omega in the low levels
through the early morning hours. We have updated the forecast
package introducing some ice accumulation across northern MN and
into NW WI.
&&
.DISCUSSION...
Issued at 130 PM CST Tue Jan 2 2024
Radar showing some light reflectivities this afternoon which
could be mix of -fzdz and -sn though half of the forecast area
has temps above freezing, so fzdz may be just dz in places.
Daytime cloud phase suggests no ice in the clouds except in the
incoming clouds near KINL. Overall, do not expect much impact
from this -fzdz, but will keep an eye on it in case it`s doing
more than I think it is.
A cold front will slip down from Canada this evening bringing
light snowfall. 500 mb 12 hour height falls indicate some good
lift potential with 10 dam falls, but moisture is lacking and
the front is fairly progressive so do not expect any snowfall to
hang around too long to amount to much. The exception is on the
South Shore of Lake Superior where good delta T`s of 18C will
add about 250 J/kg of lake-induced CAPE to the mix allowing for
shallow convective enhancement and thus greater snow
accumulations in Iron County and to a lesser extent along the
Bayfield Peninsula due to shorter fetch.
By Thursday morning skies clear and cold air should be firmly in
place with dry air aloft allowing temperatures to fall quickly
especially in areas where snow cover is fresh. In this package,
I took them below NBM means and more towards the 25th percentile
which gives below zero in the MN Arrowhead, but those could
easily be 5 degrees lower in that good radiational cooling
environment.
The cold air doesn`t linger for too long as weak ridging builds
Thursday allowing more moisture to sneak in from the southwest.
By Friday night an upper level trough spawns a weak low that
broadly meanders across the Northland impacting us with a
prolonged period (a couple days) of high PoP and low QPF over
the weekend. While QPF isn`t high, the little bit that we do
get will slowly pile up a couple of inches of snow - at the
rate of an inch or two each day. All said and done, much of the
area may see 2 to 4 inches from Friday through Sunday morning.
While just outside of our forecast timeframe, there is a large
and expansive area of low pressure that is progged to move
through the Great Lakes region early next week. As of now,
deterministic guidance only brushes us with some light snow for
NW WI; however, some ensembles (3 out of 50) do nudge that
system further west for a more impactful storm for us. WPC
cluster analysis is in good agreement with a deep upper level
trough jetting east across the country early next week, and
deterministic guidance is in fair agreement with the same
signal. We`ll have to keep a close on eye this system. For now,
we will just leave it as something large is brewing and
probably will miss us to the east, but the details are still
uncertain.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 527 PM CST Tue Jan 2 2024
MVFR stratus engulfs the entirety of the Upper Midwest this evening.
A cold front is slowly dropping south from Canada and may help to
instigate some light snow across northern MN initially. As the
boundary dips farther south PoP chances will increase for NW WI with
the potential for some Lake effect snow showers. Accumulations are
expected to be minimal across northern MN and impacts to terminals
should be negligible aside from brief instances of IFR visibility
due to falling snow. Ceilings will gradually improve north to south
tomorrow.
&&
.MARINE...
Issued at 130 PM CST Tue Jan 2 2024
Gusty northwest winds will continue overnight and flirt with
hazardous small craft conditions near the lakeshore this
afternoon and early evening. Hi- rez guidance keeps these winds
off the lake surface, so will hedge that way and keep advisory
free. Most of the next 48 hours will see lightish pressure
gradients and fairly low seas except for Wednesday morning where
waves may be 4 feet or greater along the Outer Apostle Islands.
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...None.
&&
$$
UPDATE...Britt
DISCUSSION...Wolfe
AVIATION...Britt
MARINE...Wolfe
Area Forecast Discussion
National Weather Service Grand Rapids MI
1025 PM EST Tue Jan 2 2024
LATEST UPDATE...
Update
.UPDATE...
Issued at 1025 PM EST Tue Jan 2 2024
Area radars have shown the classic signal for drizzle/freezing
drizzle this evening, but reports are not all that widespread.
Even in an area that is showing returns near the GRR airport/ NWS
office, no real drizzle is being seen at the office here as of
10pm. There have been some patchy reports of mist and freezing
drizzle upstream, but radars across the lake are already showing
a downward trend in returns. We still feel there is a chance of
drizzle and freezing drizzle overnight as a surface trough moves
in, but a widespread threat of impactful freezing drizzle does not
look likely. One item that lends credence to that is a
significant downward trend in the lift in the moist layer from the
18z NAMnest to the new 00z NAMnest at GRR. The NAMnest usually
handles these events well. Sites along the shore in the 00z run still
have decent lift, but this can be overdone/exaggerated due to
frictional piling up of the wind near the land/lake interface.
Even if that lift pans out to be real, temperatures are very
marginal/above freezing for the most part towards the lake tonight.
Bottom line...some drizzle/freezing drizzle remains possible
tonight but not expecting a significant event.
&&
.SHORT TERM...(This evening through Wednesday night)
Issued at 247 PM EST Tue Jan 2 2024
- Light Wintry Mix Could Cause Slick Spots Tonight into Wednesday
No much has changed with the overall forecast for tonight. A
shortwave trough currently moving through the UP and WI will
continue to shift east through the area this evening. There isn`t
much in the way of mid to upper level moisture with this system,
but there is a signal, especially in the Hires guidance that 850
mb and below the environment saturates. Already seeing some lower
ceilings upstream in WI below 1,000 feet, this should advect into
our area overnight and is one confidence builder that there will
be some low level moisture to work with. The question is if the
moisture will be deep enough and lift strong enough for drizzle or
light snow to develop for the overnight period. Looking at
soundings the NAM, RAP, and HRRR would support the development for
some patchy precipitation with the best chances along the
lakeshore. Therefore have kept PoPs in the 20 to 30 percent range
overnight. The other variable to consider as well is how cold the
sounding profile gets. There is the potential that cloud depths
tap into the dendritic growth zone, therefore resulting in light
snow chances, but there is also an equal chance that they don`t so
kept the wintry mix of drizzle, freezing drizzle, and light snow.
Another variable to look at is air and surface temperatures. Lows
overnight are expected to drop to around 30 degrees, comparing
surface temperatures to air temperatures from last night they are
running around 2 degrees warmer than the air temperature.
Therefore this would limit icing concerns with the marginal
temperatures around freezing. Colder spots will have the potential
for a light glaze of ice, if any freezing drizzle occurs.
- Light Snow Wednesday into Wednesday Night
Another shortwave trough moves through Wednesday with some deeper
moisture and a colder temperature profile resulting in scattered
snow showers (30 to 50 percent). Best coverage at this time looks
be be near the lakeshore. Accumulations around an inch or less
are possible. Brief busts of snow could cause reductions and
visibility and slushy accumulations on roads. Temperatures will
again be in the low to mid 30s, but winds will be lighter and from
the northwest.
.LONG TERM...(Thursday through Tuesday)
Issued at 247 PM EST Tue Jan 2 2024
- Light snow chances this weekend
After the drizzle/freezing drizzle/snow chances in the short term,
it looks like the area will see a couple of quiet days at the end of
this work week. This comes as ridging aloft and high pressure at the
sfc move across the region in the wake of the short waves tonight
and Wednesday. After cooling temperatures for a couple of days,
temperatures will rebound some for the end of the week with return
flow setting up.
We will see precipitation chances then increase for Saturday, and
persist into Sunday. A strong storm system with the southern stream
is expected to take shape near the Gulf states, and then ride up
along the Eastern U.S. Coast for the weekend. This system is
forecast to stay well SE of the area, keeping it`s impacts with it.
The significance it has to our weather however is that a northern
stream is forecast to drop down and phase with the southern stream.
This will "connect" the two systems with a front, and bring some
light precipitation to Lower Michigan. It appears that enough colder
air coming in with the northern stream will make any precipitation
over the area fall as light snow.
The main push of this will be on Saturday with the front. Temps
during the daylight hours should be in the 30s, keeping impacts to
travel minimal, other than maybe some freeze up of wet roads
Saturday night. Snow rates will not be that heavy as all of the best
moisture and forcing will stay well SE of the area. Some light snow
will remain possible on Sunday as a weak short wave moves through.
This wave will not have much moisture to work with, so minimal
impacts are expected then also.
- Active and potentially impactful pattern next week
Our focus remains on the potentially strong and active system that
could impact the area as early as early Tuesday and beyond. As
mentioned in previous discussions, we are expecting a large
amplitude long wave trough and strong jet streak to help to develop
a fairly strong storm system sometime in the Tuesday-Wednesday time
frame. The signals are there in the long wave pattern that the large
storm system will be there.
However, as one would expect seven days out, some of the details
have to be ironed with with small details having big impacts on the
sensible weather. The ensembles had been fairly consistent in taking
the sfc low near the IN/OH border, and then through Toledo, making
for a track that could bring plenty of snow to the area. The latest
runs of the deterministic models are showing some spread developing,
which is not surprising given multiple factors having to come
together for the eventual outcome this far out.
The fact of the matter is there will be a stronger system taking
shape. The track of the upper and sfc lows remains fairly uncertain
yet depending on the strength of the waves, timing of how they
eject, and how much phasing occurs. Phasing is mentioned, as there
are some models that do not phase as quickly, and keep the
sufficiently cold enough air back to the West. This would
potentially allow for mixed precipitation. Stay tuned.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 723 PM EST Tue Jan 2 2024
Several items to consider in regard to aviation weather over the
course of the next 24 hours. Those items would be lower ceilings,
freezing drizzle and snow showers.
Lower ceilings are a slam dunk as we already have widespread MVFR
ceilings in place and we expect the low ceilings to persist
through the TAF period of 00Z to 00Z. There is a fair likelihood
that we dip into IFR as ceilings try to drop below the 1,000 foot
level tonight. There are some ceilings already below 1,000 feet in
a zone from Northern Lower Michigan southwest across Wisconsin
into portions of Northern Illinois. These lower ceilings are
associated with and located near a surface trough that is
progressing southeast towards our area.
The setup from drizzle/freezing drizzle tonight is a fairly
classic one with low level moisture seen in model profiles below
5,000 feet. Lift is also noted in model overviews within this
moist layer. Drizzle and freezing drizzle looks like a good bet
tonight with the demarcation zone between the two precipitation
types coming down to surface temperatures. Looking at HRRR
guidance, we are forecast to be slightly above freezing most of
if not all of the night from MKG to AZO and points westward to
the lake. In all other areas we will likely cool just enough for
freezing precipitation to be a concern. We have FZDZ in most of
the TAF sites from 03Z to 06Z right through about 14Z Wednesday
morning.
Finally, lake effect snow showers look to develop Wednesday
morning as the lake activates with enough instability present by
that time. Scattered snow showers will primarily affect MKG but
GRR and AZO will stand a chance as well. Visibilities through the
period, both with DZ and FZDZ as well as -SHSN do not look to drop
much from VFR levels.
&&
.MARINE...
Issued at 247 PM EST Tue Jan 2 2024
Gusty southwest winds to 30 knots and waves 5 to 7 feet continue
into the early evening before subsiding late tonight with winds
turning to the west to northwest. Northwest winds however build
into Wednesday evening with wave heights of 3 to 5 feet. Winds and
waves fall below Small Craft Advisory criteria by Thursday morning
and look to remain below criteria through the weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 2 AM EST Wednesday for LMZ844>849.
&&
$$
UPDATE...Duke
SHORT TERM...RAH
LONG TERM...NJJ
AVIATION...Duke
MARINE...RAH
Area Forecast Discussion
National Weather Service Gray ME
1059 PM EST Tue Jan 2 2024
.SYNOPSIS...
Dry weather and near normal temperatures continue through the
middle of the week. A series of cold fronts will cross the
region through Thursday. Scattered snow showers expected in the
mountains. These will usher in colder weather through the
weekend, with chances for snow Saturday night into Sunday
increasing with low pressure moving through the Mid Atlantic.
High pressure passes through Monday, and then another
significant system is already increasingly likely next Tuesday
to Wednesday.
&&
.NEAR TERM /OVERNIGHT/...
1100 PM Update...Forecast is well on track this evening with
stratocu overspreading areas north of the mountains.
705 PM Update...Little to report at this hour with mostly clear
skies across the lion`s share of the forecast area, except for
stratocu just at the international border and into the Moosehead
Lake region. Did blend in some HRRR trends to the advancement
of the stratocu deck, which delayed it by a couple hours and
will allow for more efficient cooling initially across the
northern valleys... already evident by temperatures lowering
past 20 degrees there.
Previously...
Initially clear conditions will begin the night...but a pretty
expansive area of stratocu lurks just west of the Adirondacks
and across the border in Canada. Generally southwest flow ahead
of an approaching S/WV trof in Ontario will likely continue
eroding the edges of the stratocu. However once the trof cross
the area clouds will push back in from the west. Other than some
scattered snow showers in the higher terrain...it will also
affect low temps. Coldest readings will be in the lee of the
mtns in the valleys...while cloud cover holds the northern
valleys slightly warmer. Both MOS guidance and CMC regional 2 m
temp guidance had this general pattern and so I used those as a
heavy part of the blend.
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
Mtn clouds and snow showers will continue into Wed...with a
brief pause as S/WV ridging moves in behind the departing trof
and ahead of the next. As the day goes on clouds and snow
showers increase in coverage again as the next S/WV trof
arrives.
Relatively quick rebound to return flow ahead of the next wave
will keep temps slightly above normal Wed...followed by
seasonably warm temps Wed night under mostly cloudy skies.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Overview...
An active pattern develops by the later part of the work week,
and continues through at least early next week with multiple
chances for snow or rain. The first system mostly passes
offshore on Thursday, but a few snow showers are still possible.
The next system approaches this weekend, and likely brings snow
to at least southern and coastal locations. After a brief break
Monday into Tuesday, another system already looks likely
Tuesday night and Wednesday of next week with rain, snow, and
wind all possible.
Details...
The first system on Thursday looks to be the least impactful,
and affects the area with some scattered snow shower activity.
This system will be organizing and impacting the Canadian
Maritimes on Friday. So the bulk of the moisture passes by
offshore, while the shortwave on the northern branch passes
through and brings some scattered snow showers to New England on
Thursday. These two features then phase off to our east and
develop into a strong storm system, but the only impacts felt in
northern New England will be a colder airmass that arrives on
the northwesterly flow behind the system.
Dry and seasonably cool conditions are expected for Friday and
Saturday as high pressure builds in from Canada. By Saturday
night, low pressure will move northeastward through the Mid
Atlantic, bringing the increasing chance of snow into our
forecast area.
There remains a great deal of question as to how far north the
snow will spread with this system. While the high to the north
keeps a steady supply of cold air and minimizes any concerns for
mixing, it`s also likely to keep the storm track too far to the
south to get our entire CWA into the snow shield. Models have
been bouncing back and forth over the last several runs between
a solid hit, and mostly a miss to the south. The overall trend
so far this afternoon has been for the global models and their
respective ensemble suites to consolidate a little farther
north, while still keeping the storm track far enough south that
northern areas miss the bulk of the moisture. There`s still
room for this system to trend farther north, but at this time
POPs were generally increased to bring high likelies into far
southern New Hampshire and the southwest coast of Maine.
After a brief break on Monday with high pressure passing
through New England, eyes are already turning to the next system
for next Tuesday and Wednesday. Although it`s still 7-8 days
away, models have been very consistent in bringing a
strengthening system into the Northeast, though there remains
high uncertainty as to whether this would be an inland cutter
with wind and rain, or a storm featuring more coastal
redevelopment and snowfall. Either way, POPs are quite high from
this far out and were only reduced from NBM`s 90% POPs due to
the risk of timing discrepancies from this far out. While it`s
still too early to sort out the details, a potentially impactful
system already looks likely in the Tuesday-Wednesday time frame
next week. Additionally, tides will be approaching their
monthly peaks by the middle to later portions of next week, so
this will be one more factor to monitor with this system.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Widespread VFR and no LLWS forecast thru Wed night.
A passing wave will increase cloud cover north of the mtns
starting late tonight...but MVFR CIGs are only expected to reach
as far south as HIE. MVFR CIGs may linger thru Wed night at HIE.
Long Term...Scattered snow showers may bring brief restrictions
and MVFR ceilings on Thursday, but otherwise mainly VFR
conditions prevail through Saturday, except at HIE where MVFR
ceilings are more likely through midday Saturday. Snow is then
likely across southern and coastal terminals with IFR conditions
Saturday night and Sunday. Snow and restrictions are still
possible across northern terminals, but will be more dependent
on the track of the storm. VFR conditions then return Sunday
night and Monday.
&&
.MARINE...
Short Term...Winds and seas will remain below SCA thresholds
thru Wed night.
Long Term...A cold front crosses the waters on Thursday as a
developing low pressure system passes east of the waters.
Northwesterly gales are possible Thursday night behind this
system. High pressure builds across the waters for Friday and
Saturday. Another developing low pressure system moves into the
waters Saturday night and Sunday, with northeasterly gales
possible.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.
&&
$$
UPDATE...Casey
NEAR/SHORT TERM...Legro
LONG TERM...Clair
Area Forecast Discussion
National Weather Service Marquette MI
525 PM EST Tue Jan 2 2024
.SHORT TERM...(This evening through Wednesday)
Issued at 325 PM EST TUE JAN 2 2024
Key Messages:
-Cold front passing today to bring chances for light snow, impacts
not expected during the day.
-Additional surge of cold air brings another round of lake effect
snow late tonight into Wednesday morning; a few inches of snow are
possible in the NW snowbelts.
Water vapor and RAP analysis show a shortwave moving over the UP
this afternoon, with winds shifting to the NW betraying the weak
associated cold front. This first wave has not kicked up any
precipitation so far, but will not rule some out in the eastern UP
with the frontal passage and some potential lake enhancement (lake
temperatures around 4C and 850mb temperatures aloft cooling to
around -8 C indicate marginal delta-Ts for LES).
Into tonight, another shortwave (currently evident over far western
Ontario) will drop through, providing a reinforcing shot of CAA and
resulting lake effect overnight in the NW and eventually NNW snow
belts. Though 850mb temperatures should only be around -8 to -10C by
late evening, they should be around -12C by the early hours of
Wednesday morning. With that, model soundings for tonight show
inversion heights rising from around 4kft to around 8kft, with
moisture depth increasing through a fairly elevated DGZ. That, in
addition to dryer low levels in soundings, will contribute to lower
snow ratios than we`d generally like to see in lake effect, but we
should still be around 12 to 15:1 overnight. By 12Z Wednesday,
guidance is showing widespread QPF amounts of a trace to a tenth of
an inch (>80% chance) across the western and eastern UP, with a 50-
80% chance of locally higher QPF in excess of a tenth of an inch.
That translates to a widespread 1-3 inches, with locally higher
amounts of 3-5 inches possible in the usual spots (eastern Alger
county, and the higher terrain of the north-central and western UP).
Some trace amounts may even extend more into the central UP as winds
shifting more northerly the second half of the night causes our LES
bands to shift more southward.
Otherwise, look for temperatures in the upper 20s and lower 30s this
afternoon to fall into the lower to mid 20s overnight while skies
remain mostly cloudy.
.LONG TERM...(Wednesday through Tuesday)
Issued at 307 PM EST TUE JAN 2 2024
Key Messages:
-Accumulating lake effect snow is expected in the northwesterly to
north-northwesterly snow belts Wednesday. Be mindful of the road
conditions when driving!
-The lake-effect snow dwindles Wednesday night and eventually ends
Thursday.
-These next several days will feel pretty `normal` for this time of
year.
The lake-effect snow continues over the northwest to north-northwest
wind snow belts Wednesday as a secondary shortwave low drops through
Lake Superior and brings much colder air across the U.P. throughout
the day. This raises the delta-Ts over the lake from around 13C to
20C by the end of the day, increasing the convective potential of
the snow bands Wednesday into Wednesday evening. While this will
improve lapse rates within the boundary layer and thus increase the
strength of the snow bands, it will also lower the inversion slowly
throughout the day from 5 kft to 4 kft. In addition, with high
pressure ridging to our west bringing some drier air into the region
(as can be seen by the model guidance showing an inverted trough
hanging over us Wednesday and Wednesday night), snowfall rates and
totals will be muted a bit, even despite the improved convective
potential. With model guidance also slightly lowering the QPF
amounts associated with the lake-effect snow too, thinking we will
see a snowfall total between 2 to 4 inches over the northwest to
north-northwest wind snow belts from tonight through Wednesday.
While snowfall rates could come down at half an inch per hour at
times in the strongest cells, given the convective nature of the
lake-effect bands, thinking the quickly accumulating snowfall will
come in quick `bursts` within the snow bands. Therefore, just be
careful driving Wednesday as surfaces could be slick and
visibilities could become sharply reduced to a half mile at times
over the northwest to north-northwest wind snow belts.
As ridging continues to move into the area Wednesday night, expect
the the lake-effect snowfall to begin dwindling and slowly back to
the northwest. As the high pressure associated with the ridging
moves through central Wisconsin Thursday, expect the winds to
continue backing to the west; with winds becoming westerly and drier
air moving over us, the lake-effect snowfall for the event ends by
Thursday evening. Between Wednesday night to Thursday evening,
expect only around an extra inch of snowfall in the north-northwest
to west-northwest wind snow belts, with the greatest accumulations
over the eastern U.P. With the sky clearing out, we could get some
fairly normal low temperatures for this time of year come Wednesday
and Thursday nights; thinking lows will be in the teens over the
course of those two nights.
The rest of the period looks somewhat normal for January as we move
into this weekend and early next week. Temperatures will be much
closer to normal than what we saw in December, although they may be
a little bit above normal still at the end of the day. Likewise, we
may see some additional light snowfall this weekend as a Clipper
touches our area. The one break to the normalcy could come at the
end of the period, when a large vertically-stacked low pressure from
the southern Rockies moves into the Eastern U.S. While model
guidance has generally trended the main low further south due to
stronger ridging over the Great Lakes, this system will still need
to be monitored in the additional forecast packages, as it could
(40% chance for now) bring some significant snowfall to the U.P.
next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 525 PM EST TUE JAN 2 2024
MVFR conditions will continue at IWD and SAW through the forecast
period. CMX will go from MVFR to IFR later tonight as clipper snow
will move in. Lake effect snow showers will then cause MVFR/IFR
conditions at CMX through the rest of the forecast period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 307 PM EST TUE JAN 2 2024
Northwest winds of 20 to 25 knots continue over Lake Superior this
afternoon before becoming 20 knots or less for a few hours late
tonight. Behind a secondary shortwave low that moves through late
tonight through Wednesday morning, north-northwesterly winds pick up
to 20 to 25 knots across the lake starting Wednesday morning. Once
the cold air advection ceases Wednesday night, the winds calm back
down to 20 knots or less again. As a Clipper low over northern
Ontario interacts with a high pressure leaving the Great Lakes
region for the Southeastern U.S./Mid-Atlantic Thursday night, some
west-southwesterly winds of 20 to 30 knots move across the lake
Thursday night into Friday morning before dropping below 20 knots
again Friday evening. An additional shot for notable winds looks
possible this weekend too as a shortwave low lifts from the Northern
Plains through Lake Superior.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...LC
LONG TERM...TAP
AVIATION...07
MARINE...TAP
Area Forecast Discussion
National Weather Service Phoenix AZ
512 PM MST Tue Jan 2 2024
.UPDATE...00Z Updated Aviation Discussion.
&&
.SYNOPSIS...
A couple of weather systems will move across the area through this
weekend, bringing good chances for accumulating precipitation,
especially with the system over the weekend. While precipitation
across the region seems to be a rare occurrence as of late, the
main concern will be threats for freezing temperatures late this
week and especially early next week across the lower deserts. Near
normal temperatures over the next couple of days will dip to well
below normal late this week and extend through early next week.
&&
.DISCUSSION...
Skies have cleared across the region from the system that mainly
impacted southeastern Arizona yesterday. Higher clouds ahead of
the next system are beginning to push into the southern beaches of
California, with the low circulation nearing the California/Oregon
coast this afternoon. This feature is in association with another
troughing feature that will continue to dig southeastward through
tomorrow, with the trough center reaching northern Arizona
tomorrow evening.
This troughing feature will provide the next chances for
precipitation across the region mainly Wednesday evening into
Thursday morning. However, not a ton of moisture will be
associated with this system, as ensembles depict PWAT`s generally
not exceeding 0.50" for the event. Thus, while NBM PoP`s continue
to advertise in excess of 70% chances for the lower deserts,
expectations for much accumulations will be relegated mostly to
the higher terrain areas. The latest HRRR shows a broken line of
showers, in association with the cold front, moving through
southcentral AZ tomorrow evening. Thus, the latest projections are
for most areas across the Phoenix metro to receive 0.10" or less
for this event. Snow levels will lower as the front moves through
the area, but any snow is expected to remain generally above 5500
feet. Enhanced breeziness will accompany the frontal passage,
generally gusting 15-25 mph across southcentral AZ. Stronger
winds are expected further west, with isolated areas in the higher
terrain of southwestern Imperial County gusting in excess of 40
mph, along with gusty winds 30-35 mph reaching the lower deserts
of Imperial County during the late afternoon and evening hours
before weakening during the overnight hours.
Moving into the latter portions of the week, skies will clear
through the evening hours by Thursday, so overnight temperatures
will plummet to near freezing in isolates spots across the lower
deserts. These chances will extend through Friday as well. The
latest NBM probabilities for reaching freezing for places like
Casa Grande and Arizona City are around a 60-80% chance for those
two mornings. Otherwise, temperatures will remain well below
normal across the region going into this weekend.
The next weather system will pack a stronger punch than the middle
of the week system, as the troughing feature dives southward from
the Arctic late this week and into the weekend. Mid-level heights
will be much more negatively anomalous, with even the 540 dam
contour digging into the Desert Southwest with this system. As a
result, snow levels will fall much more significantly with this
system, as low as 4000 feet on Sunday. However, this troughing
feature will also have limited moisture, with PWAT`s generally
maxed around 0.50". However, due to the stronger dynamics,
precipitation amounts are expected to be higher than tomorrow`s
system. Latest projections suggest rain amounts on the order of
0.25" or less continue for the lower deserts of southcentral AZ,
with higher amounts expected in the higher terrain (including snow
equivalent). Thus, this will be the first noteworthy winter system
for the season, with snow levels low enough to key an eye on snow
accumulations and potential impacts from the snow.
Heading into early next week, skies will clear Sunday night,
resulting in temperatures plummeting to the coldest temperatures
of the season expected. Widespread freezing temperatures across
the lower deserts look likely (60-80%) for both Monday and Tuesday
mornings, so freeze products will be needed for the Phoenix metro
should this forecast hold for early next week. Otherwise,
temperatures will remain well below normal through the middle of
next week, as ensembles continue to advertise general longwave
troughing persisting across western CONUS.
&&
.AVIATION...Updated at 0012Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major weather impacts are anticipated through the next 24
hours. A deck of high clouds will pass over the area this evening,
clearing briefly early tomorrow morning before mid to high clouds
build in again and begin to lower over the afternoon hours. Winds
will follow their typical diurnal tendencies with sustained speeds
aob 7 kts. A period of very light and variable winds is possible
preceding the E`rly switch this evening. Just beyond the current
TAF period, a cold front is expected to pass over the terminals
bringing lower ceilings, temporarily stronger winds out of the W
to NW, and the potential for some passing light showers. The main
aviation concerns associated with this are expected be low
ceilings (30% chance of MVFR or lower ceilings) and strong, gusty
NW winds associated with the frontal passage.
Southeast California/Southwest Arizona including KIPL and KBLH:
The main aviation weather concern through the TAF period will be
lower ceilings and strong W`rly winds associated with a cold
front passing over the terminals late tomorrow morning. Until the
front arrives between approximately 17-19Z, winds will remain
light (aob 5 kts sustained) at both terminals, with extended
periods of variability at KBLH and directions veering from SE to
SW this evening at KIPL. After the front arrives, SCT-BKN low
clouds with bases mostly aoa 5 kft will prevail through the end of
the period, and winds will pick up out of the W, especially at
KIPL.
&&
.FIRE WEATHER...
Near normal temperatures are expected through midweek, but the
unsettled weather will continue. One mostly dry weather system
will exit the area early today, while another more potent system
moves in from the west on Wednesday. Moisture levels will remain
slightly elevated with MinRHs above 30%, while rain chances
increase from west to east during the latter half of Wednesday.
The bulk of the rainfall will occur Wednesday night with CWR
mostly below 30% in the lower deserts to as high as 70% over the
higher terrain. After light winds today, breezy southwest to
westerly winds are likely for much of the area on Wednesday.
Below normal temperatures will settle into the region starting
Thursday with overall dry conditions Friday and Saturday, but with
MinRHs remaining near 30%. An even colder weather system is then
expected for Sunday bringing additional chances for precipitation
and another round of breezy to potentially windy conditions.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Young
AVIATION...Whittock
FIRE WEATHER...Kuhlman
Area Forecast Discussion
National Weather Service Topeka KS
918 PM CST Tue Jan 2 2024
.KEY MESSAGES...
-Dry and seasonable weather expected through midweek.
-An active pattern brings a few opportunities for snow - one on
Friday and another early next week.
&&
.UPDATE...
Issued at 918 PM CST Tue Jan 2 2024
Starting to see some shallow fog develop outside of the small
patch of stratus that continues to drift south towards MHK.
Initially the conditions appear ideal for radiational fog, but
dewpoint temps continue to fall into the middle 20s (lower than
previously forecast and what crossover temps would suggest), and
the 02Z RAP and 00Z NAM want to increase winds at the top of
the boundary layer to 10KT or 15KT which could increase dry air
entrainment into the boundary layer before sunrise. Overall
think fog development will continue. The patch of stratus over
Washington and Marshall counties is slowly expanding now.
However there are enough negatives with the dewpoints and 925MB
wind progs to go with widespread dense fog or thoughts of an
advisory at this time.
&&
.DISCUSSION...
Issued at 212 PM CST Tue Jan 2 2024
A shortwave trough and weak surface boundary are moving through the
CWA today, shifting winds from the southwest to the north. High
clouds have been present in our sky northeast of a mid-level low
over western Texas. Tonight, a batch of low stratus clouds in
Nebraska could move into the area with fog formation also looking
probable. Areas of fog will continue into Wednesday morning before
dissipating. Dry and seasonable weather is in store through midweek
as a result of surface and mid-level ridging over the region.
In the meantime, our next storm system currently located off
the Pacific Northwest coastline will be dropping southward over
the Four Corners region by Thursday. Precipitation will move
into southwestern KS as lift increases ahead of the advancing
mid-level low and as a surface low approaches the Red River
Valley early Friday. POPs increase from southwest to northeast
across the CWA early Friday as precip moves into the area. Light
snow looks to be the dominant precipitation type through the
morning hours with forecast soundings showing a nearly saturated
column all below freezing. Minor accumulations of less than an
inch our occur in central portions of the state for the morning
commute. Models then show only minor spread, and thus good
consensus, on temps warming above freezing during the afternoon.
As a result, snow could mix with some rain, or at least melt
upon impact through the afternoon. Light snow could continue
into the night before tapering off by Saturday morning. In
general, this system still appears to be low impact with temps
above freezing for much of the event. Both the LREF (long range
ensemble forecast, which includes the ENS, GEFS and GEPS) and
the NBM have a 30-50% chance of 1". The going forecast is closer
to 0.5" through this timeframe.
Another mid-level trough looks to work over the central CONUS this
weekend, so will keep slight chance POPs in the forecast. Light
snow could again occur, but accumulations are not expected at
this time. A larger and more impactful system could then affect
the region Monday and Tuesday of next week. With stronger
forcing and colder temperatures, this system comes with a higher
potential of accumulating snowfall. The LREF currently shows an
80-90% chance of at least 1" of snow, and a 50-70% chance for
at least 3", while the NBM has a 50-70% of 1" and a 20-40% of 3"
across the area. Given that this system is still a week out
there remains high uncertainty on the evolution and track, so
changes to the forecast are likely.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 440 PM CST Tue Jan 2 2024
With surface ridging passing over the area tonight, radiational
fog is becoming more probable. Most CAMs show some fog
developing but maybe not in the same place. But the MOS guidance
is not that excited about fog. Forecast soundings show light
winds throughout the boundary layer as high clouds pass to the
east. So the setup for radiational fog is favorable. Will start
off with VSBY around 1SM, but based on afternoon dewpoint
temps dense fog is possible. If more of the model guidance had
a similar picture, I might be more aggressive. Forecast
soundings show the boundary layer mixing out late in the
morning.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Wolters
DISCUSSION...Teefey
AVIATION...Wolters