Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/01/23
Area Forecast Discussion
National Weather Service Dodge City KS
414 PM CST Sat Dec 31 2022
...updated aviation...
.SHORT TERM...(This evening through Sunday night)
Issued at 1202 PM CST Sat Dec 31 2022
18Z obs are showing west to northwest flow in the mid levels and
the moisture in the mid levels is currently at a lull which is
leading to the sunny skies across western Kansas. Upstream a large
area of Pacific moisture is currently streaming from Colorado back
to the coast of California. This is ahead of an approaching
shortwave which will affect Sunday night through Monday`s weather.
At the surface a weak lee side low is located in the Oklahoma
panhandle with a surface trough/wind shift line extending into
central Kansas.
Tonight should be fairly quiet as the surface low moves into
western Kansas and the winds should remain light. There will be a
few passing high clouds during the night and some approaching mid
level clouds from the southwest ahead of the next shortwave
towards morning. Overall efficient radiational cooling as lows
will fall into the 20s and 30s.
Sunday with the approaching upper level trough heading towards the
four corners we should see an increase of clouds during the
morning and be mostly cloudy for the whole area towards mid to
late afternoon. Winds should continue light as the surface
low/trough will remain in western Kansas. Highs will be in the
mid 50s.
Sunday night we should start to see the first bands of
precipitation develop along the front range of the Rockies with
the approaching storm system. Ahead of the system a warm front
will lift towards the I-70 corridor overnight with the HRRR
hinting at the potential of some advection fog and/or drizzle
towards morning. I kept this out of the forecast as of now but
it is something to monitor over the next few forecast cycles.
Light rain could begin to develop towards the Colorado border by
sunrise however it looks like most of the area should be dry as
lows fall into the mid to upper 30s.
.LONG TERM...(Monday through Saturday)
Issued at 155 PM CST Sat Dec 31 2022
Main story of the long term is the upcoming storm system which
will mostly affect northeastern Colorado, northwestern Kansas, and
Nebraska with a large winter storm and the trend of being more in
the dry slot for much of our area keeping the chances of rain and
snow lower and the amounts lower as well.
Latest deterministic models have continued the northern track of
the 500 mb low through northeast Colorado and most of the better
forcing in northwest Kansas. Along with that a pocket of drier air
comes in the 700 mb- 850 mb level during the day on Monday. The
exception is the latest deterministic Euro which has moved a
little further south from the previous run and has introduced
rainfall amounts of 0.10-0.25 inch across the area. After
collaboration with neighboring offices and WPC I decided to keep
the drier solution which would give much of the area little to no
QPF with the exception of our northwest and I-70 corridor
counties. The ensemble Euro and GFS also continue their respective
trends of almost no QPF for the GFS and a few tenths from the
Euro. Overall it looks like mainly a wind event for the area as
the surface low deepens in eastern Colorado which will produce
gusty southwest winds and highs in the mid 50s.
Monday night into Tuesday the storm system should exit into
northeast Nebraska and on the backside a cold front will usher in
colder air and breezy northwest winds across much of central and
western Kansas. Any lingering precipitation could quickly switch
over to snow mainly along the I-70 corridor with little to no
accumulations.
Tuesday should remain breezy and cooler with highs in the 40s.
The middle of the week we should stay on the cool side of the jet
stream and highs will stay in the 40s. By Friday an upper level
ridge will usher in warmer temperatures and will be ahead of
another large trough in the southwest which could be a potential
weather maker for the region for next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 444 PM CST Sat Dec 31 2022
VFR is expected through TAF pd. Winds should remain light and variable
tonight and into the AM. A weak backdoor front works in during the
day tomorrow with winds becoming NE 5-15 kt in its wake. Any weather
impacts with an eventual passing weather system looks to remain outside
of this TAF pd.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 29 54 37 56 / 0 0 10 30
GCK 28 53 35 54 / 0 0 10 30
EHA 36 57 38 56 / 0 0 20 20
LBL 31 55 38 57 / 0 0 10 20
HYS 26 52 34 52 / 0 0 10 40
P28 33 55 40 57 / 0 0 0 20
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Tatro
LONG TERM...Tatro
AVIATION...Sugden
Area Forecast Discussion
National Weather Service Grand Forks ND
725 PM CST Sat Dec 31 2022
.UPDATE...
Issued at 725 PM CST Sat Dec 31 2022
Areas of fog continue to be reported, with transient pockets of
dense fog (1/2-1/4 mile). Conditions are highly variable with
reports of riming/heavy frost in the dense freezing fog and very
light mist mainly associated with these dense pockets. Actual
freezing drizzle in the east may have transitions out of the
area, so the main impacts are going to be where this freezing fog
develops and tracks and current conditions with the previous
advisory are highly variable. High resolution guidance indicates
that this will persist and eventually new dense freezing fog may
overspread our entire forecast area through the late
evening/overnight. The strongest signal for improvement by RAP
sounding is when winds finally shift to the west and increase
Sunday, but that leave a very moist/stagnant air mass in place
overnight matching the idea of expanding impacts. Considering the
expected trends I went ahead and expanded the dense fog advisory
for our entire area and ran it through 9am Sunday. I`m also using
extra caution considering holiday travel tonight.
&&
.SHORT TERM...(This evening through Sunday night)
Issued at 220 PM CST Sat Dec 31 2022
Key Messages
1. Dense fog will continue at least through midnight. Fog may
persist after as confidence is quite low in duration of the fog.
2. Freezing drizzle is possible tonight, especially in northwest
Minnesota near the Red Lakes. Be prepared for slick conditions.
DISCUSSION
The surface pattern is dominated by a weak surface low over eastern
South Dakota, contributing to southerly flow and moisture advection
over the Northern Plains. This has allowed for some weak upslope
flow in eastern North Dakota which has caused areas of fog. Fog is
the most dense along where moisture advection exists ahead of the
850mb trough. It is unclear how long this dense fog may exist,
but it does appear like it will at least continue through
midnight. With the surface inversion, fog will unlikely get
better, so the Dense Fog Advisory has been expanded northeastward
and extended through midnight.
Weak warm air advection ahead of the 850 trough will allow for some
freezing drizzle potential in northwest to north central Minnesota.
Soundings indicate a pretty solid moist 1km deep layer associated
within this region of WAA. This potential will exist through 09z/3
AM one warm air advection is able to exit the area.
For tomorrow, primarily zonal flow will keep us mild and quiet for
the most part. Stratus may continue to linger around, but confidence
is low in that department as this stratus has hung around for
several days. Impacts should remain low for New Years Day.
.LONG TERM...(Monday through Saturday)
Issued at 220 PM CST Sat Dec 31 2022
Key Messages -
*Normal to Above Normal highs and lows for the first part of January
*Light snowfall along the ND/SD line into west central Minnesota
Monday into Tuesday
Ensembles/cluster analysis continues to place more weight on a
southern track or soln with the upcoming system Monday into Tuesday.
As a result little snow expected from the system along and north of
the I94 and Hwy 10 corridor. Highest amounts expected in this
forecast area will be for Grant county. The probability of an inch
or more is 50% or higher along and south of a line from Havana to
Wahpeton to Park Rapids with just a 20% for 4 inches along a line
Hankinson to Fergus Falls to Nimrod with higher values to the south
as a 40% chance exists in southern Grant at Herman and Hoffman. In
the wake of the system some patchy blowing snow will be possible in
the southern valley as sustained north to northwesterly winds
approach 20mph Tuesday.
With the quasi-zonal flow the rest of the week into next weekend
temperatures will not vary much this week with highs in the teens
and low 20s most days. The exception will be Wednesday in the wake
of the system with highs in the single digits and teens. Lows this
week will be in the single digits above and below zero. Normals for
the first week of January are highs in the mid teens and lows around
zero.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 544 PM CST Sat Dec 31 2022
Fog and stratus are likely to continue through the TAF period,
with dense fog this evening responsible for lowest visibilities
to 1/4 mile or less. How long dense fog lasts is hard to say as
there are upstream indications of improvement in the west as
winds shift to the southwest, however guidance supports
decreasing winds locally and continued pooling of low level moisture
which may limit improvement. Eventually winds do shift more to
the west Sunday and increase and that should be at least enough
for prevailing MVFR rather than IFR conditions.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Dense Fog Advisory until 9 AM CST Sunday for NDZ006>008-014>016-
024-026>030-038-039-049-052>054.
MN...Dense Fog Advisory until 9 AM CST Sunday for MNZ001>009-013>017-
022>024-027>032-040.
&&
$$
UPDATE...DJR
SHORT TERM...Perroux
LONG TERM...JK
AVIATION...DJR
Area Forecast Discussion
National Weather Service Wichita KS
525 PM CST Sat Dec 31 2022
.SHORT TERM...(This evening through Monday night)
Issued at 300 PM CST Sat Dec 31 2022
FORECAST HIGHLIGHTS THE NEXT 7 DAYS:
* Fog potential southeast Kansas late tonight into Sunday morning.
* Above normal temperatures through Monday.
* Precipitation chances Monday-Monday night.
* Near to below normal temperatures Tuesday-Thursday, with a
warming trend late week and next weekend.
With weak moist advection into a developing warm frontal zone,
thinking fog potential will increase late tonight into Sunday
morning over southeast Kansas, mainly southeast of the KS Turnpike.
Bufkit RAP soundings support patchy to areas of dense fog, so later
shifts may need to monitor for a possible dense fog advisory.
Fortunately, temperatures should remain above freezing, so patchy
slick spots on roads and bridge decks are unlikely.
Main forecast highlight is the anomalously deep western CONUS upper
trough ejecting onto Mid-America by Monday. Deterministic and
ensemble consensus continues to favor the highest precipitation
chances associated with this system over eastern Kansas, where deep
moisture transport and large scale ascent coincide. Have sided with
this model consensus for the official forecast. However, the
deterministic ECMWF solution continues to be the deeper and more
negatively tilted outlier with regard to the upper system, with also
a further south warm frontal position, which would favor a more
widespread footprint of precipitation across the region. If the
model consensus starts to trend closer to the ECMWF solution, later
shifts will need to increase rain chances and amounts further west
across the forecast area.
Warm thermal profiles support a precipitation type of mostly
rain, with a few embedded thunderstorms over southeast KS, amidst
anomalous moisture and associated marginal instability. Severe
weather isn`t expected, although given the strong wind fields and
marginal instability, cannot rule out small hail and gusty winds
with the strongest activity. As the system pulls away and colder
air filters south, could see a period of a light rain/snow mix
over central Kansas Monday night into early Tuesday, especially if
the stronger/more wrapped up ECMWF solution verifies. The heavier
wintry precipitation should remain well north of the region, so
am not expecting impacts from wintry weather across central KS.
.LONG TERM...(Tuesday through Saturday)
Issued at 300 PM CST Sat Dec 31 2022
Chilly Canadian high pressure building in from the north should
support a return to near to below normal temperatures Tuesday-
Thursday, with lows in the teens-20s, and highs in the 30s-40s. By
late next week and next weekend, model consensus supports
temperatures warming back to mostly above normal readings in the 40s-
50s. In wake of the early week system, meaningful precipitation
chances look low through next weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 519 PM CST Sat Dec 31 2022
Some cirrus clouds will continue to spread eastward across the
region through the period. We`re still expecting to see some
increasing potential for fog and stratus across southeast KS
during the predawn hours on Sun likely lowering flight categories
at KCNU while lingering into the morning hours on Sunday before
mixing out. Light easterly winds are expected to develop as low
pressure organizes over the Southern Plains during the day on
Sunday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 34 54 43 57 / 0 0 0 50
Hutchinson 32 54 39 54 / 0 0 10 50
Newton 34 54 41 55 / 0 0 0 50
ElDorado 37 54 44 58 / 0 0 0 50
Winfield-KWLD 38 57 47 61 / 0 0 0 50
Russell 27 51 35 52 / 0 0 10 50
Great Bend 29 53 37 52 / 0 0 10 40
Salina 30 52 38 52 / 0 0 10 50
McPherson 31 53 39 53 / 0 0 10 50
Coffeyville 43 62 52 65 / 0 0 0 80
Chanute 40 59 49 62 / 0 0 0 70
Iola 39 58 48 62 / 0 0 0 70
Parsons-KPPF 42 60 50 63 / 0 0 0 70
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...ADK
LONG TERM...ADK
AVIATION...MWM
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
824 PM CST Sat Dec 31 2022
.UPDATE...
Issued at 824 PM CST Sat Dec 31 2022
No significant changes to going forecast this evening. Primary
concern continues to be a period of mixed rain/snow/freezing rain
this evening from the I-39 corridor east-northeast through the
northern Chicago metro suburbs before low level temps and wet
bulbs warm solidly above freezing. Did raise pops a bit across the
north and made some temp/dew point and wet bulb adjustments based
on near term obs trends, but otherwise forecast appears to be in
good shape.
Have seen some spotty light precipitation early this evening
mainly along/north of about a Sterling to Waukegan line. Surface
temps were generally in the 32-35 degree range in this area per
ASOS/AWOS and private sensors, with RAP soundings depicting sub-
freezing wet-bulb profiles below cloud base. This will likely
support a brief period of mixed rain/snow and perhaps even a few
sleet pellets as precipitation continues to increase in coverage
over the next couple of hours. Persistent low level warm advection
will gradually warm surface temperatures and dew points solidly
above freezing by midnight, with gradual low level saturation
working to increase wet bulbs and turn precip to all by midnight.
Some patchy slick spots are possible mainly on thinner untreated
surfaces such as sidewalks and parking lots this evening however.
This precipitation is associated with a pair of mid-level short
waves traversing the region. The first, currently transiting WI,
largely worked to saturate the mid-levels. The second and stronger
wave currently crossing the mid-upper Missouri Valley will bring
stronger forcing across the region overnight, expanding rain over
the forecast area toward/after midnight. The wave will exit the
region prior to sunrise allowing rain to exit to the east early
Sunday morning. Lingering low clouds and patchy fog will likely
linger into the daytime hours however.
Updated digital and text forecasts available.
Ratzer
&&
.SHORT TERM...
Issued at 243 PM CST Sat Dec 31 2022
Through Sunday night...
Main forecast highlights through the period include:
* Period of Rain across northern IL tonight, with some potential
for a wintry mix far north at onset early this evening.
* Some fog plausible late tonight into Sunday morning following
the period of rain.
* Potential for more substantial low clouds and fog developing
Sunday night and persisting into Monday.
An upper level 120+ kt upper level Pacific jet streak is currently
oriented from the northern Rockies east-southeastward into the
Mid-Missouri Valley. The exit region of this jet streak is
expected to nose eastward across IA and into northern IL into
tonight, and will be accompanied by a quickly moving low amplitude
mid-level impulse. Ultimately, these features will support a
period of precipitation across a decent portion of northern IL
tonight.
Increasingly lower-level warm air advection and a lead mid-level
disturbance over IA is already resulting in an area of
precipitation across eastern IA and far northwestern IL. This
activity will be fighting a drier low-level airmass as it
continues to move eastward into northwestern IL and southern WI
late this afternoon and early evening. While this may result in
many of the echos on the radar not reaching the ground initially,
evaporative cooling of the lower levels is likely to, at least
initially, offset the warming of the column from thermal
advection. This may thus support a period the precipitation
onsetting as a light wintry mix into early this evening before the
warm air advection wins out and warms the column enough to
support all rain by mid to late this evening. The main potential
for a brief 1 to 3 hour wintry mix looks to be across the northern
tier counties in IL near the WI state line. A minor coating of
accumulation is possible, but this is not likely to lead to major
travel disruptions. Areas farther south look to warm enough prior
to the onset of precipitation to support all rain by mid to late
this evening.
It appears the best period of rain will occur around, or a bit
after midnight tonight as the main upper level disturbance and
exit region of the upper level jet begin to nose into the area.
Forecast guidance even suggests that a band of lower-level
frontogenesis may even focus a band of some heavier showers
within a region of steepening mid-level lapse rates right across
northern IL (north of I-80) for a couple hours overnight during
the period of strongest large scale forcing. Currently, the timing
of this better period of rain across northeastern IL looks to be
in the 12 am to 4 am time period tonight. Accordingly, POP and QPF
values have been boosted to 60 to 70%, and 0.25 to 0.5",
respectively.
As the rain ends from west to east overnight, signs point to low
clouds and fog development by daybreak Sunday morning. While
guidance has not recently had a good track record with fog
development, it appears the increasing low-level moisture from the
south may make the fog more likely into Sunday morning. For now, I
have added patchy fog wording to the forecast, though if trends
continue to support this it may need to be hit a bit harder in the
forecast. Aside from lingering morning fog and low clouds, Sunday
looks to be primarily quiet. Temperatures should be milder, with
highs generally in the 40s.
Winds are expected to turn northeasterly Sunday night as a warm
front sharpens just south of the area in response to developing
low pressure over the TX panhandle. This warm front will
gradually shift northward across IL into Monday. The main concern
for our area Sunday night into Monday will again be tied to low
clouds and fog, some of which could be dense. For now, I have
added patchy fog wording for areas generally along and south of
I-88 Sunday night through Monday morning.
KJB
&&
.LONG TERM...
Issued at 333 PM CST Sat Dec 31 2022
Monday through Saturday...
Monday begins with a warm frontal boundary approaching the area from
the south tied to our next big storm system. 30s and lower 40s in
the morning will rise into the mid 40s to lower 50s by Monday
afternoon. The front is forecast to move through the area Monday
afternoon and evening with efficient WAA continuing to take place
through the night. This will result in warming conditions overnight
with 40s and lower 50s in the evening followed by 50s to around 60
degrees by daybreak on Tuesday. The Euro is a bit slower to bring
the front through which would result in slightly, but notably,
cooler conditions, especially in the northern CWA.
The widespread rain expected with this storm will begin feeding in
from the southwest through the latter half of the evening, perhaps
preceded by a few scattered pre-frontal showers through the
afternoon. PWAT forecasts Monday evening and night continue to
exceed one inch area-wide and push 1.5" across the southern CWA;
note that 1.28" is the highest PWAT ever measured by a radiosonde
out of ILX through the month of January. Perhaps the most notable
change in the forecast since yesterday is the uptick in instability
driving up the thunder and heavy rain potential. Anywhere from 100
to 400 J/Kg of elevated low level CAPE, deep layer saturation, and
plenty of synoptic support from the left exit region of a 45-60 kt
LLJ suggest widespread moderate to heavy rainfall. The GFS, Euro,
and NBM like to think areas roughly southeast of I-55 will see
heavier rain and, resultantly, higher QPF where PWAT values are
expected to be a bit higher, forcing from the LLJ will likely be
greater, and where the Euro thinks there will be significantly more
instability. The widespread, heavy rain will taper off to the
northeast early Tuesday morning with a few lingering showers
possible through the morning and perhaps into the early afternoon.
QPF across most of the area is averaging out around 0.4" to 0.8".
However, as previously mentioned, further southeast in the CWA may
see higher rain totals. The GFS is the most aggressive in this area
spitting out around 1.5"+ of QPF through Tuesday morning. The Euro
is thinking closer to 1" in these parts.
Now to touch on the thunder potential. As noted above, the increase
in forecast instability has both increased and expanded thunder
chances across the area. A thunderstorm certainly seems possible now
area-wide, though the greatest thunder chances remain south of I-80
where the greater instability and stronger LLJ are expected. A not-
so-terrible shear profile featuring as many as 45 kts of 0-1 km
shear and some modest low level veering suggest a non-zero severe
thunderstorm potential. Deep convection doesn`t appear too likely
given that just about all of our instability will be confined in the
lowest 300mb. However, that fact shouldn`t put too much of a damper
on a strong wind threat.
The majority of Tuesday will be rain-free underneath a sizable dry
slot aloft even preceding the passing of the cold front at the
surface. The front will be passing over Tuesday evening pulling
temperatures from mid 50s and lower 60s Tuesday afternoon back to
near or below freezing by Wednesday morning. Highs in the 30s can
then be expected through the rest of the workweek. The cooler
profile could provide us with some snow showers on Wednesday if
moisture and forcing play out as expected. Moisture availability has
been shaky for Wednesday, but models have come to a good consensus
on a good deal of moisture wrapping around the backside of the
system and resaturating the 950-700mb layer, especially closer to
the IL/WI state line. Some modest PVA is anticipated through this
layer along and east of the low level trough axis. The NBM is still
rather conservative on the snow potential compared to other models
which have almost all come to agree that we will see at least some
snow fall on the area. A lack of additional forcing and little to no
snow production within the DGZ should keep snowfall on the lighter
side. Plus, the above-freezing surface temps should inhibit
accumulation, especially on roadways which will inevitably be even
warmer. The greatest potential for snow will be Wednesday afternoon
into the earlier part of the evening. Light snow may last through
the night for parts of northwest IN and locales closer to the lake.
The lake-effect potential we`ve been eyeing is looking modest at
best with a lack of forcing and the not-so-impressive cold air mass
providing little lake-induced instability. However, some lake
enhancement toward the end of the event over the aforementioned
areas appear certainly possible.
Doom
&&
.AVIATION...
For the 00Z TAFs...
The primary aviation concerns through the TAF period are as
follows:
* Period of showers this evening, most likely at RFD but possibly
also DPA/ORD/MDW/GYY
* Second period of shower after midnight most likely at
DPA/ORD/MDW and possibly GYY
* Quickly deteriorating cigs/visbys toward sunrise with high
confidence in IFR and medium (but growing) confidence in LIFR
conditions
Regional radar imagery depicts an area of showers stretching from
eastern Iowa into southern Wisconsin, which are associated with a
compact system lifting northeastward into central Wisconsin.
Over the next few hours, the showers should continue
eastward through a pocket of dry low-level air may chew up most
raindrops before the reach the ground. Confidence is highest in
precipitation occurring this evening at RFD where the low-level
dry air is least prevalent. For this reason, will maintain the
inherited TEMPO group at RFD and VCSH groups at ORD/DPA/MDW/GYY.
Cigs and visbys will remain VFR through midnight.
After midnight, a second system is expected to track across
northern Illinois leading to the development, if not
invigoration, of showers primarily over DPA/MDW/ORD/GYY between
the hours of 07-11Z. As showers taper toward sunrise, cigs and
visbys are expected to rapidly deteriorate thanks to increasing
subsidence and a weakening low-level pressure gradient behind the
departing wave. High resolution model guidance unanimously shows
cigs building below 500 feet and visbys below 1 mile from sunrise
to early Sunday afternoon, giving high confidence in IFR and
medium (and growing) confidence in LIFR conditions. For now, will
introduce 1-2SM visbys and OVC004 to OVC005 cigs at all terminals
from 11Z onward keeping in mind even lower conditions may need to
be introduced in future TAF packages.
Confidence in how fast conditions improve Sunday afternoon is
lower than average owing to a lack of traditional mechanisms to
scour our low-level moisture. For one, low-level winds will
slacken in response to a surface pressure col stalling overhead.
As a response, there will be little in the way of moisture or
temperature advection, allowing for conditions to more or less
stagnate. Interestingly, model guidance ubiquitously advertises a
gradual return to VFR conditions Sunday afternoon (maybe thermal
mixing even with the low sun angle?), so will hedge
optimistically and to the same. However, it would not be
surprising in the least to see low clouds remain well into Sunday
afternoon and beyond.
Borchardt
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.
&&
$$
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Area Forecast Discussion
National Weather Service Memphis TN
536 PM CST Sat Dec 31 2022
...New AVIATION...
.DISCUSSION...
(This evening through next Friday)
Issued at 149 PM CST Sat Dec 31 2022
GOES-16 Satellite trends this afternoon place an upper level
trough axis stretching from the Northern Plains back through
portions of the Mississippi Valley and Southern Plains.
Meanwhile, at the surface a weak cold front stretches from New
York back through Middle Tennessee and portions of West Tennessee
and Arkansas. GOES-16 Visible satellite trends have continued to
indicate clearing of the morning fog/low stratus resulting in
mostly sunny to partly sunny skies. As of 2 PM CST, temperatures
across the Mid-South range from the lower to middle 50s north and
60s south. The potential for fog and/or stratus tonight along
with strong to severe thunderstorm potential late Monday afternoon
into early Tuesday morning are the predominant challenges in this
afternoon`s forecast issuance.
Surface and shortwave upper level ridging will build into the
Mid-South tonight into New Year`s Day. Short term model soundings
indicate the boundary layer will remain moist below a subsidence
inversion. This moisture combined with relatively clear skies
initially and temperatures falling tonight in the 50s to near
dewpoints in the 50s will result in the development of patchy to
areas of fog this evening into New Year`s Day morning. Any fog
that develops is anticipated to gradually lift into a low stratus
layer as boundary layer winds begin to increase towards morning.
The evening shift will monitor visibility trends and consider
dense fog headlines if conditions warrant. Highs on New Year`s Day
will be in the middle 60s to lower 70s with the warmest
temperatures over North Mississippi. Highs on Monday will be in
the upper 60s to lower 70s.
Short term models indicate an upper level trough off the
California Pacific Coast will move into the Rockies/Southwest
United States Sunday night, then becoming negatively tilted as it
moves northeast into the Upper Midwest by Monday evening. Upper
level forcing will increase as 60-80 DM 500 mb height falls
spread across the Mid-South Monday night into Tuesday morning and
favorable upper level divergence produced by the right entrance
region of a 180 300 mb upper level jet spread across the Lower
Mississippi Valley. Favorable upper level forcing, moderately
steep 700-500 mb layer mid-level lapse rates, and favorable
kinematics (speed and directional shear) suggest a potential for
strong to severe thunderstorms across portions of the Mid-South
between late Monday afternoon into Tuesday morning.
However, the main limiting factor continues to be the amount of
available surface/mixed layer instability during this
aforementioned time. GFS/ECMWF ensemble data continues to indicate
the best corridor of marginal instability remaining mostly over
portions of East Arkansas (south of I-40) and over Northwest
Mississippi (west of I-55) late Monday afternoon into Monday
evening then tapering off into the remainder of North Mississippi
late Monday night into early Tuesday afternoon.
An early look at potential times for severe weather would be
between late Monday afternoon into early Monday evening as a warm
front moves north across the Mid-South and when a quasi-linear
line of convection along a cold front moves through the area late
Monday night into Tuesday morning. Large hail, damaging winds, and
perhaps a tornado or two might be possible but the amount of
instability may end up tempering the overall potential and
coverage of severe thunderstorms across the Mid-South especially
north and east away from the aforementioned areas. Stay tuned...
In addition, heavy rainfall will be possible with this convection
as precipitable water values rise to above the 99th percentile (1.5
inches) for January with 1 to 3 inches of rain forecast mostly along
and west of the Mississippi River.
Long term models indicate a couple of mid-level shortwave troughs
will rotate around an upper low in the Ohio Valley by the middle
of next week. Cooler temperatures but no precipitation is
anticipated with the passage of these upper level synoptic
features. Temperatures will gradually moderate towards next
weekend as upper level ridging builds back into the Mississippi
Valley.
CJC
&&
.AVIATION...(00Z TAFS) Issued at 526 PM CST Sat Dec 31 2022
Backed off on the low visibility tonight based on latest HRRR and
NBM guidance as well as expected wind around 4-5 kt overnight. Low
CIGs will still result in LIFR conditions. South wind will
increase to around 8-11kt tomorrow and high clouds will overspread
the Midsouth. VFR conditions should prevail tomorrow after
midmorning into tomorrow night.
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
PUBLIC FORECAST...CJC
AVIATION...JDS
Area Forecast Discussion
National Weather Service Morristown TN
908 PM EST Sat Dec 31 2022
...New UPDATE...
.UPDATE...
Issued at 904 PM EST Sat Dec 31 2022
A bit more clearing than earlier forecast, but fog and low clouds
are increasing. Some of the fog is locally dense, and an SPS for
localized dense fog has been issued. Will continue to monitor in
case the dense fog gets widespread enough to trigger a dense fog
advisory. Have increased fog coverage with this update, and
decreased PoPs/shower coverage as precip has been staying mainly
to our north.
&&
.SHORT TERM...
(This evening through Sunday)
Issued at 320 PM EST Sat Dec 31 2022
Key Messages:
1. Majority of the rain exits east late this afternoon, but a few
light showers/sprinkles will accompany the front later this
evening. Patchy fog overnight.
2. Clouds hang around through most of the day tomorrow with above
normal high temperatures.
Discussion:
Overview: A cold front moving into middle TN will move across our
area this evening, exiting east of our area before midnight. The
last of the heavier precip is currently moving through the east TN
Valley now. The latest HRRR shows this line exiting east around 4 to
5 PM EST. Then, expect a few light showers/sprinkles to accompany
the front later this evening. QPF amounts will be lighter with the
activity along the front, where only a few hundredths of an inch of
precip is expected. Patchy fog is expected overnight. Overnight
lows remain mild as we only dip down into the mid to upper 40s,
which is 15 to 20 degrees above normal.
With weak westerly flow, low-level moisture remains trapped in the
valley tomorrow so expect clouds to be around through most of the
day. Some areas could see a few breaks late in the afternoon but
expect more clouds than sun. Highs will again be above normal with
temps in the upper 50s to mid 60s.
&&
.LONG TERM...
(Sunday night through next Saturday)
Issued at 320 PM EST Sat Dec 31 2022
Key Messages:
1. A strong storm system will bring a return of rain to the region
Tuesday through Wednesday after dry and and unseasonably mild
conditions on Monday.
2. High winds are possible in the mountains by Tuesday, in addition
to widespread moderate to heavy rainfall and thunderstorms. A few
strong to severe thunderstorms are possible Tuesday evening, mainly
in southern areas.
3. Cooler temperatures return by Thursday onward.
Sunday Night through Wednesday
At the start of the period, upper ridging will be building into the
region with surface high pressure centered across the southeastern
U.S. This will continue a warm and dry pattern ahead of a
trough/system initially located over the Rockies. 500mb heights are
expected to reach 5,800 meters or higher, values typical in May,
which emphasizes the extent of above normal temperatures expected
early in the week. Heading through the day on Monday, the
aforementioned trough will eject out of the Rockies and become
increasingly negative in its tilt as it progresses northeastward
into the Great Plains. This will also be coincident with the surface
low deepening to 995mb on a similar track. There still remains minor
timing and spatial differences regarding the evolution and track of
the surface low, but the overall consensus is for it to track up
towards Iowa on Monday night as an open wave. Based on the timing
and track of the system, PoPs will increase from west to east later
on Tuesday and continue through much of the day on Wednesday as a
coupled jet structure sets up aloft.
As the system follows this trend and progression, the consensus is
for the 850mb jet to strengthen to 50 to 60 kts northwest of the
region by Tuesday morning. This will also come with a tightening of
the MSLP gradient over the mountains and adjacent foothills. As
such, confidence continues to increase for potential of mountain
wave winds out ahead of the system. With lingering uncertainty in
exact details and available data, messaging will be kept largely the
same.
Regarding the potential for thunderstorms, overall dynamics will
support organized, potentially strong convection by Tuesday evening.
Deep-layer shear will be in excess of 50 kts area-wide with low-
level SRH of over 200 m2/s2. These values will be enhanced by the
continually strong 850mb jet. Much of the uncertainty still lies
with instability and how far northward it reaches into the area. The
12Z GEFS, for example, shows 80% or more probability of SCP values
exceeding 1 in southern portions of the area but only 30% to 40%
probability of over 500 J/kg of surface-based CAPE. For the 250 J/kg
threshold, however, values are above 60% across the southern half of
the region. There is also a slightly slower trend in the arrival of
convection with this most recent model run that could shrink the
window of concern during this timeframe. Overall, confidence in the
dynamics and potential for sufficient instability are both high
enough for elevated concern of strong/severe convection. In any
case, locally strong winds are certainly possible with any
thunderstorm due to the low-level jet.
With respect to potential for flooding, anomalous moisture above the
90th percentile and depth to the warm cloud layer will be in place,
emphasizing potential for efficient rainfall rates within any
convection. At the time of this forecast issuance, the current FFG
indicates that rainfall totals of 3" in a 6-hour period would be
needed to cause flash flooding. This value will definitely change in
the coming days, but the likelihood of two main rounds of rain, one
Tuesday evening and one Wednesday morning, will keep concerns for
localized flash flooding. This will be maximized in the southern
half of the region with better expected coverage. Nevertheless, the
downward trend in overall rainfall totals continues with most places
unlikely to reach close to this threshold. Overall, messaging for
impacts from this system will remain the same with the main
difference being a slight increase in confidence for severe
potential and a decrease in confidence for flooding based on recent
trends.
Thursday through Saturday
By the end of the period, troughing will build into the region with
a more northwesterly low-level flow pattern. This will all make the
case notably cooler temperatures than earlier in the period. With
some lingering low-level moisture, low-end PoPs were kept in the
forecast, focused in the mountains. There is certainly potential for
transition to light snow showers, but this looks to be of minimal
impact and limited to the highest elevations if it occurs. Dry and
seasonally cool conditions will continue into the weekend as strong
high pressure sets up in the eastern U.S.
&&
.AVIATION...
(00Z TAFS)
Issued at 559 PM EST Sat Dec 31 2022
CHA/TYS will likely start off VFR with MVFR to start at TRI, and
while the details are still murky at best it appears all sites
will deteriorate in fog/low cigs overnight with conditions at
least as low as IFR likely by later tonight. Expect some
improvement late in the period with VFR conditions expected before
the period ends.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 50 66 49 69 / 10 0 0 10
Knoxville McGhee Tyson Airport, TN 48 63 44 68 / 10 0 0 10
Oak Ridge, TN 47 61 44 66 / 10 0 0 10
Tri Cities Airport, TN 47 60 40 67 / 20 0 0 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...SR
LONG TERM....BW
AVIATION...
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
427 PM MST Sat Dec 31 2022
.DISCUSSION...(This Evening Through Saturday)
Issued at 153 PM MST Sat Dec 31 2022
Upper trough beginning to dig into the western CONUS and will
eventually eject into the central plains this week, supporting
heavy snow over parts of the region. Confidence in snow amounts
remains medium to low on the northern side of this system, which
is basically all of the FA outside of scentral SD, due to concerns
on dry air to the north and the mean location of the progged LL
FGEN max. Weak impulse traversing the region this afternoon,
resulting in some light snow over the higher elevations of the
central and southern BH, with dry air winning out elsewhere. This
band of weak lift will shift SE this afternoon with possibly a few
light snow showers lingering over scentral SD this evening.
Attention then turns toward the vigorous upper trough taking aim
on the region. Lead northern split wave will support a WAA regime
over the far SW Sunday afternoon evening, allowing increasing
chances for snow there. Snow will then then slowly shift ENE
Sunday night into Monday, with snow spreading into most of far
southern SD by Monday morning. Forecast models are starting to
come into some agreement with the storm track and some of the
dynamics, namely where the best FGEN and associated snow band will
likely be. Right now most forecast models are progging the axis
of strongest FGEN over NE into scentral SD AOA h7. The strongest
lift and heaviest snow would be expected just to the south of the
FGEN max. This is also starting to be confirmed in the RAP and
HRRR, which both support the heaviest snow on the southern side of
most medium range model solutions. To the north of the FGEN band,
snowfall will be much lighter, with amounts likely in the adv
range. However, given the long duration of the event, current
forecast amounts come close to low end warning numbers and felt
given the continued uncertainty in model solutions a northward
extension of the watch was warranted, esp along the eastern
foothills of the BH where some upslope enhancement still looks
possible. Again, the northward side of the snow shield has the
highest uncertainty with large foretasted ranges given intrusion
of dry air and potentially weaker lift north of the FGEN max and
feel snow amounts are likely over done there. Further west, have
opted for an adv over southern Campbell and Weston Counties given
an earlier start to snow per the lead trough with 2 day total
amounts up to 8 inches possible in the far southern portion of
these counties. Still expecting breezy northerly winds Monday
night into Tues over scentral SD, with some blowing snow possible.
Snow will shift east and end Monday night across the area west to
east, possibly lingering over scentral SD into Tues morning. Not
much cold air behind this system with seasonal temps the remainder
of next week with dry conditions.
&&
.AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening)
Issued At 424 PM MST Sat Dec 31 2022
Leftover very light rain/snow showers over south-central SD will
end by 03z. VFR conditions are expected through 12z Sunday. An
approaching storm system will bring MVFR/IFR CIGS into the far
southwest reaches of the CWA Sunday morning, slowly progressing
northeast through the afternoon. KGCC won`t be affected before
21z Sunday with KRAP after the forecast period.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Watch from late Sunday night through Tuesday
morning for SDZ026-030>032-042>044-046-047-049.
Winter Storm Watch from Sunday evening through Tuesday morning
for SDZ027-029-041-074.
WY...Winter Weather Advisory from 3 PM Sunday to 11 PM MST Monday for
WYZ055-058.
&&
$$
DISCUSSION...JC
AVIATION...Helgeson
Area Forecast Discussion
National Weather Service Las Vegas NV
645 PM PST Sat Dec 31 2022
.SYNOPSIS...Widespread rain, high elevation snow, and gusty winds
will impact the region tonight and tomorrow. Model simulations show
that this active weather pattern will continue through the first
week of the New Year.
&&
.UPDATE...Current satellite imagery shows moisture streaming into
the western United States from the Pacific, which has brought
impressive rainfall to parts of California. Snowfall estimates of
around a foot are being reported from sites in the eastern slopes of
the Sierra. Most of the moisture is being blocked by the Sierra at
this time. That being said, rainfall has already started at Bishop
and in sections of the southern Great Basin. Short term guidance
shows a slower advance of precipitation into the Las Vegas Valley.
Confidence is decreasing in precipitation reaching Las Vegas before
midnight, thinking it will mainly reach the city in the early
morning hours. Gusty southerly winds should persist through the
night, but gust intensity is coming into question as observations
are around 5 to 10 knots lower than previously expected.
&&
.SHORT TERM...Through Sunday night.
Beginning to see more reports of light rain spilling over the
southern Sierra into the Owens Valley. Otherwise, the Mojave Desert
is windy as south-southwest winds are occurring well out ahead of
the potent trough off the central California coast. From snow
pillows, I`d estimate between 5-7 inches of snow at the higher
elevations in Inyo County.
Latest radar imagery show next pulse of heavy rain moving into
central California with reflectivity enhancements increasing on the
western slopes of the southern Sierra indicating onset of moderate-
heavy precipitation. Progressive nature of the trough will push this
precipitation shield south into south California late this
afternoon/evening. HRRR indicates heavier rain breaking out across
the western Mojave Desert this evening before pushing east into
southern Nevada later this evening. Onset of precipitation around
Las Vegas still continues to be around 9-10 pm, while main band
shift through between midnight and 5 am New Years Day.
That main band continues east through Mohave County AZ Sunday
morning with embedded thunderstorms possible across southern Mohave
County where CAPE is the greatest. Wrap around moisture/instability
in colder air on backside of trough will keep showers going across
southern Nevada and eastern through much of New Years Day as well.
Strong wind gusts of 40-50 mph have been observed in northwest San
Bernardino County, while Angel Peak in southern Nevada consistently
60-70 mph since 10 am. Pockets of these stronger winds will continue
through tonight. Post-frontal winds out of the northwest will remain
gusty New Years Day.
Am not going to add any additional products to the mix as elevations
above 6000 feet in Mohave County will probably see less than 3
inches between late Sunday afternoon and Sunday night.
Pleasant temperatures ahead of the storm today but 8-12 degrees
colder behind the cold front tomorrow.
.LONG TERM...Monday through Saturday.
Sunny and dry start to Monday morning expected with below-average
temperatures and breezy southwest afternoon winds. Thereafter, there
is quite a bit of change to the forecast compared to our analysis 24-
hours ago. An additional round of moisture will approach the western
CONUS, bringing PoPs to the region Monday night into Tuesday. QPF
has dropped substantially, which coincides with IVT plumes
indicating the weak atmospheric river will take a further south
track inland. That said, QPF has not completely dropped off, with
moisture making its way south and around the Sierra Nevada Mountain
Range and over the San Bernardino mountains. ECMWF ensemble means
put forecast PWAT values around half of an inch across the Mojave
Desert Monday night. With this system will come some of the lowest
precip-combined snow levels of the season, bottoming out around 2700
feet in Las Vegas. Not expecting anything in the way of
accumulation, especially with the greatly diminished forecast
precipitation totals, but cannot discount the chance of snow
flurries on the western side of the Las Vegas Valley, and even a
dusting in higher elevations of Summerlin and Red Rock. No impacts
expected with this system other than impacts that accompany snow-
related distracted driving. Remember to keep 2 times the distance
between your car and the car in front of you, as slick roadways are
more often caused by light precipitation than a deluge.
A brief break in wintry weather expected Tuesday and Wednesday
morning before the next wave approaches. As with the early-week
system, this forecast is trending drier with a less favorable
trajectory for Mojave Desert rainfall. QPF has dropped for the
valleys and inland mountains, but increased for the Sierra Crest, as
the bulk of the available moisture smacks into the mountain range
and wrings out with minimal spill over. High uncertainty remains
with this forecast, so details are subject to change as we approach
this event.
Through midweek, temperatures will remain a few degrees below
seasonal averages, then will gradually increase toward average late-
week.
&&
.AVIATION...For Harry Reid... As a storm system moves across the
region, conditions will deteriorate at the field later this
afternoon and evening. Decreasing CIGs can be expected by late
afternoon, falling below 5kft this evening. Showers are also
expected in the vicinity of the field after 02Z, with showers
becoming likely between 06Z and 12Z. Showers will become more
scattered tomorrow after 12Z, but the threat of precipitation and
decreased CIGs will persist into tomorrow afternoon. Winds will
also become gusty out of the north by Sunday afternoon as a cold
front moves through the Vegas Valley. It should be noted that if
the New Years Eve fireworks display along The Strip does occur at
midnight as scheduled, a period of additional low-level obscuration
due to smoke can be expected in the vicinity of the field.
For the rest of southern Nevada, northwest Arizona and southeast
California...Gusty winds, low CIGs, and areas of light to moderate
precipitation will result in poor flying conditions across the
region today into Sunday. Additionally, downslope winds off the
Sierra near KBIH could lead to sudden cross winds and LLWS in that
area. Slowly improving conditions are forecast west to east across
the area Sunday afternoon as the storm system exits the region.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
$$
UPDATE...Meltzer
SHORT TERM...Pierce
LONG TERM...Varian
AVIATION...Planz
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