Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/09/23
Area Forecast Discussion
National Weather Service Amarillo TX
853 PM CST Fri Dec 8 2023
...New UPDATE...
.UPDATE...
Issued at 840 PM CST Fri Dec 8 2023
Looking at the latest model guidance this evening, HREF members
continue to suggest a band of snow will move south across the
Panhandles tonight into tomorrow morning along and behind a cold
front. There has been decent run to run consistency showing
localized enhancement in precipitation south of the Canadian River
Valley across Oldham and Potter counties near sunrise. This
scenario seems reasonable given northerly winds have caused higher
totals to the south of the Canadian River during similar events in
the past. Have gone ahead and slightly increased snow amounts,
resulting in a slightly larger area of 1 to 2 inches of snow,
across these two counties. The previous Winter Weather Advisory
has been expanded southward to Oldham and Potter given this
potential.
Will have to keep a close eye on model and radar trends once the
band begins to set-up, as there is some guidance showing some
higher snow totals a bit further east along and south of the
Canadian River for Carson, Grey, and Roberts counties. Confidence
in that is low at this time, but will continue to closely monitor
that potential through the overnight hours.
Muscha
&&
.SHORT TERM ...
(This evening through Saturday night)
Issued at 250 PM CST Fri Dec 8 2023
Dry weather is expected to take a small break tonight as models
continue to project an upper-level trough move across the
Panhandles by Saturday afternoon. With the upper-level pattern
shift, look for an associated cold front to follow with latest
CAMs projecting showers and front over the Oklahoma Panhandle
around midnight. Snow continues to remain the dominate
precipitation type for the western half of the Panhandles, but a
cold rain can’t be ruled out the further east the showers spread
during the push. What has been a big change in the last 24 hours
has been the amounts. Currently the common trend for both the SERF
plumes and other high resolution models has been to see much
stronger bands of precipitation move across the Panhandles
tonight, which has also been something that the NBM has been very
slow to take in. As it stands, chances of receiving greater than
inch of snowfall has improved quite a bit in the northwest, with
half of Cimarron County now over 70%. These chances have also
spread further south with city of Dalhart now projected to be over
an inch as well. In fact should the HRRR prove to be the better
outlook, then it is possible for these values spread much further
into the Central Panhandles. Given the sudden spike and its
continued presence during the morning and afternoon runs, a Winter
Weather Advisory has been issued for the Northwest from midnight
Saturday till 12 pm that afternoon. By then, models expect the
cold front to be south of our area with showers rapidly
diminishing during the early afternoon hours.
Moving into the second half of the active pattern that Saturday
afternoon, models expect a strong upper-level jet to settle in
behind the frontal passage. Look for the jet to bleed down into
the lower-levels and create gusty northerly surface winds across
the Panhandle. As it stands winds could easily reach into the 25
to 30 mph range with gust reaching near 40 mph not our of the
question. While, RH values will thankfully keep fire danger low,
these winds could pick up any lose snow sitting on the ground and
create pockets of blowing snow across the north. As for
temperatures, expect them to drop behind the front with afternoon
highs tomorrow in the 40s. Meanwhile, overnight lows will once
again return to below freezing with many locations in the 20s and
teens.
Scoleri
&&
.LONG TERM ...
(Sunday through next Thursday)
Issued at 250 PM CST Fri Dec 8 2023
Northwest flow aloft on Sunday will gradually become more zonal on
Monday and then will become southwest on Tuesday as our next upper
level closed low drops southward through the Great Basin. A cold
front will also move through the Panhandles early Tuesday morning in
association with the next system to our west. Southwest surface
winds may reach 20 to 30 mph with higher gusts across the southwest
Texas Panhandle on Sunday as a lee-side low replaces a surface high.
Elevated fire weather conditions may also be found across the
southwest Texas Panhandle where the stronger winds will overlay the
lowest relative humidities.
Low level moisture should increase across the Panhandles on
Wednesday as southeast winds increase in response to lee-side
troughing. The moisture combined with increasing southwest flow
aloft and minor short waves embedded in the flow will help to
produce showers across the Panhandles Wednesday morning through at
least Thursday. Models have come into a little better agreement
with the upper level low pushing southward through Utah and then
east across the southern Rockies Wednesday and Thursday. This
pattern could bring Pacific and Gulf of Mexico moisture over the
Panhandles which could lead to some beneficial precipitation if
everything can come together just right. But, the models are still
in a state of flux and they are changing each day, so fingers
crossed! The latest models have come in a bit warmer, which would
lead to more of the area staying rain and less of the area switching
over to snow. But these details will work themselves out as we get
closer.
&&
.AVIATION...
(00Z TAFS)
Issued at 531 PM CST Fri Dec 8 2023
Main concern will be wintry precipitation with this TAF cycle. All
sites will likely have snow showers starting after 09z for KGUY
and eventually KAMA around 12z. Reduced visibility due to falling
snow combined with low ceilings may drop sites to IFR and
potentially LIFR for a few hours. Snow should be south of all
terminals by late morning and conditions should improve to VFR.
Breezy to gusty northerly winds behind a front are forecast after
snow ends and will continue through the remainder of this TAF
period.
Muscha
&&
.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX 29 42 21 54 / 10 60 0 0
Beaver OK 31 47 20 53 / 60 30 0 0
Boise City OK 26 39 17 51 / 70 40 0 0
Borger TX 30 44 21 56 / 30 70 0 0
Boys Ranch TX 28 43 17 55 / 30 70 0 0
Canyon TX 28 43 19 54 / 0 50 0 0
Clarendon TX 33 46 24 55 / 0 30 0 0
Dalhart TX 25 40 15 50 / 70 70 0 0
Guymon OK 28 43 17 52 / 70 40 0 0
Hereford TX 27 43 19 54 / 0 40 0 0
Lipscomb TX 30 47 21 55 / 30 30 0 0
Pampa TX 30 44 22 53 / 20 60 0 0
Shamrock TX 32 48 24 55 / 10 30 0 0
Wellington TX 33 49 24 55 / 0 20 0 0
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...Winter Weather Advisory from midnight tonight to noon CST
Saturday for TXZ001-002-006-007-011-012.
OK...Winter Weather Advisory from midnight tonight to noon CST
Saturday for OKZ001.
&&
$$
SHORT TERM...11
LONG TERM....15
AVIATION...05
Area Forecast Discussion
National Weather Service Dodge City KS
522 PM CST Fri Dec 8 2023
...Updated Aviation...
.KEY MESSAGES...
- Light accumulating snow likely across extreme southwest Kansas,
mainly Elkhart area, focused on Midnight to 6 AM CST very early
Saturday morning. Elsewhere, very little accumulating
precipitation.
- Seasonal temperatures and light winds Sunday through Tuesday in
between storm systems.
- Widespread precipitation event increasingly likely across
southern High Plains (especially West Texas), extending as far
north as portions of the central High Plains and southwest
Kansas mid to late next week (Dec. 13-15 time frame)
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 340 PM CST Fri Dec 8 2023
Short Term forecast emphasis mainly on tonight`s rain changing to
snow event across far southwest Kansas...and how much snow will
accumulate. An elongated, low amplitude shortwave trough continued
to push its way across the Colorado Rockies. Water vapor loop and
RAP analysis showed the exit region of the cyclonically-curved jet
streak entering southeast Colorado and adjacent far western Kansas.
This led to a blossoming of radar echo across eastern Colorado and
far western Kansas, but much of this was virga (precipitation not
reaching the surface), as low level relative humidity was in the 25-
30% range. Eventually, the low level airmass will moisten enough for
precipitation at the surface, but most likely will not occur across
far west central and southwest Kansas until well after dark.
The past few HRRR runs have shown respectable precipitation rates
across mainly Stanton and Morton County overnight, mainly in the 06-
12Z time frame with some 0.10"/hr rates. Any precipitation rates
this high will likely be over a rather small region, i.e. residence
time of these rates will be low as the mid level frontogenetic zone
will keep pushing south. Along with the modest precipitation rates
will be a cooling of the column to change rain over to snow. With
initial ground temperatures fairly warm, and given how short-
duration this event will be, we do not expect much accumulation. We
will, however, carry around 1 to 1.5" snowfall around the Elkhart
area, with a few tents of an inch of snow up to Johnson-Ulysses, and
perhaps as far east as Liberal, but much of the latest ensemble
model data (HREF, SREF, and of course NBM), keep heavier snow across
the Raton Mesa region toward the I-25 corridor of south central
Colorado. The latest 19z NBM run has the 50% Prob of Exceedance of
2" or greater across western Baca County, CO and points west...with
2"+ probabilities dropping off significantly east of Springfield,
CO.
Give all the above-stated, we will not be issuing any winter
headlines for tonight`s event after coordinating with WFO PUB and
WFO AMA (thanks!). Any light accumulating snow will be ending around
or shortly after sunrise Saturday, but strong winds out of the
northwest will be felt across all of southwest and west central
Kansas. We will continue to lean more toward 90th Percentile NBM
wind speeds for Saturday, which tends to work quite well in strong
pressure gradient situations in the wake of low pressure systems. As
far as temperatures go, we will see a pull back in temperatures for
sure, but there is no arctic air behind this storm, so with some
sun, we should still see afternoon temperatures in the mid to upper
40s for highs.
.LONG TERM...(Sunday through Friday)
Issued at 340 PM CST Fri Dec 8 2023
The first part of the Long Term period, Sunday through at least
Tuesday, will be quiet with seasonal temperatures of highs generally
in the 50s each day and lows in the 20s. The synoptic scale pattern
will be a nebulous west-northwest flow regime between the departing
trough and a new system developing out across the Great Basin earl
next week. An anticyclonic wave-breaking low will form and
essentially become "cut off" from the main polar branch of the
westerlies over Utah-Nevada-Arizona region. There is very high
confidence in this evolution of the synoptics with high run-to-run
continuity of all the global models and their associated ensemble
systems. The huge question is what happens once this low forms.
There is actually pretty good agreement between the EPS and the GEFS
Ensemble mean 500mb Height+Vorticity pattern at F+132...both showing
low center across northern Arizona with a vorticity anomaly centered
over southern/central Arizona (valid 00Z Thursday). Both ensemble
systems show this height/vorticity moving slowly east into New
Mexico over the next 24 hours. This slow movement and a position
southwest of Southwest Kansas would favor development of a robust
warm, moist conveyor belt across the southern High Plains. There
would be plenty of time to infuse Gulf of Mexico moisture into the
warm conveyor belt ahead of this upper low. Unsurprisingly with this
type of pattern, global models are showing a lot of 2-3 Day QPF mid-
late next week, especially to our south across much of West Texas.
There is a large degree of uncertainty in how far north this
substantial precipitation axis will reach into Kansas, and this is
seen in the latest 72-hr QPF >= 0.25" Probabilities at 20-35% across
southwest Kansas (vs. 60-75% south of us across portions of West
Texas). Understand that this event is still 5-7 days out, so there
will be a lot of adjustments to this forecast, including how much
(if any) of this precipitation will fall in the form of snow, so
keep checking back.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 517 PM CST Fri Dec 8 2023
Skies will be cloudy for much of tonight through Saturday morning
however it does look like the ceilings should stay in VFR status
for all terminals during this time. A cold front will move across
western Kansas tonight and we should expect winds to pick up
towards sunrise Saturday morning. Sustained winds of 20 kts with
gusts of 30 kts or more will be possible between 12Z-00Z. A fast
moving storm system will also lead to a chance (40-50%) of some
light snow mainly around the LBL area between 06Z-12Z. Snowfall
accumulations will be light but this could lead to some brief
lowered surface visibilities (~5 SM) during this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 31 47 21 52 / 30 0 0 0
GCK 28 45 19 51 / 40 0 0 0
EHA 28 44 19 52 / 70 30 0 0
LBL 29 46 18 51 / 60 10 0 0
HYS 30 46 20 51 / 10 0 0 0
P28 36 51 24 53 / 10 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Tatro
Area Forecast Discussion
National Weather Service Des Moines IA
527 PM CST Fri Dec 8 2023
...Updated for the 00z Aviation Discussion...
.DISCUSSION.../Tonight through Friday/
Issued at 154 PM CST Fri Dec 8 2023
Key Messages:
- Rain showers move over southeast Iowa tonight.
- Scattered snow showers with chances up to 50% over northern
Iowa on Saturday. While snow accumulations will be under an inch
in most places, the combination of falling snow and gusty winds
would reduce the visibility at times.
- There is a high (>90%) chance of wind gusts over 25 mph on Saturday
with a 50-70% chance over 40 mph in parts of northwest Iowa.
- Conditions seasonable to above normal and favoring dry conditions
until at least late in the week.
Details: GOES upper level water vapor imagery shows moisture
streaming northeastward over the central part of the county ahead of
the longwave trough over the western US. There is a 500mb and
surface low nearing International Falls this afternoon and the cold
front associated with these features is through Iowa with breezy
winds from the west or northwest prevailing. Temperatures have
reached the low or middle 50s in most locations, which is still 15
degrees above normal.
Focus is on the longwave trough with a shortwave trough moving
through the base of it this afternoon, which can be seen on GOES
imagery as a tight cyclonic spin over southern Colorado. QG
convergence and low level theta-e advection is advancing ahead of
this shortwave moving over the southeastern half of the state this
afternoon into tonight. As the mid-level forcing arrives with the
shortwave, scattered showers will develop and lift northeastward
over particularly the southeastern part of the state, though chances
will exist back into portions of central Iowa. Soundings continue to
show thermal profiles supportive of an all rain event tonight. As
the previous shift noted, trend has been to focus rainfall over
southeastern Iowa with chances and amounts tapering off into central
Iowa. National Blend of Models (NBM) probabilities of a half an inch
or more of rainfall peak in far southeastern Davis County near 50%
so a lucky location or two could pick up that, but probabilities
favor less than a half an inch. GFS and NAM show elevated
instability working up into southeastern Iowa, though not sure
anyone in our forecast area will hear thunder/see lightning so have
kept out any mention. The forcing will lift northeastward along with
the shortwave trough with all of the rainfall east of our forecast
area by sunrise Saturday.
The aforementioned 500mb low will drop toward the state on Saturday,
but much of its forcing will reside north of the state. The low will
bring low clouds into the state and forecast soundings show a
deepening of moisture in the low levels. This is particularly true
over northern Iowa with less moisture and saturation farther south
into central and southern Iowa. At the same time, lapse rates are
steepening causing low level instability to develop. The instability
is just into the dendritic growth zone, but it does look like
convective snow shower potential continues, particularly north of
Highway 20 where the deeper saturation will set up. The HRRR shows
this well with streaks of QPF and many models have at least light
QPF over portions of northern Iowa. So, this is where chances are
ranging from 20% around Highway 20 to between 30 to 50% near the
Minnesota border in north central Iowa along with light amounts of
QPF. Snow totals will average around a half an inch over northern
Iowa meaning that a few places will see little if any snowfall while
a few places will be closer to an inch. Trends will be monitored in
the depth of moisture in case chances need to be dropped farther
south with potential area shown in the 12z HREF 6 hr max QPF, HRRR,
or WRF-ARW/FV3.
It will be colder along with conditions turning blustery as the
pressure gradient tightens across the region with NBM probabilities
of wind gusts higher than 25 mph above 90% statewide and wind gusts
higher than 40 mph above 50% over portions of northwest into north
central Iowa including Estherville and Algona. Forecast soundings
from the NAM, GFS, and RAP show wind gusts of 30 to 40 mph as well,
which was higher than the initial NBM wind gusts. Thus, wind gusts
were increased blending in some of the NBM90th and HRRR. With winds
just approaching advisory criteria, no headline planned for now.
However, with snow showers and these winds, blowing snow may reduce
visibilities under 3 miles at times.
All of the snow shower activity will end early Saturday evening and
winds will gradually decrease overnight into Sunday morning. As the
trough axis pulls east, the upper level flow will become from the
northwest and then more zonal toward midweek as a western US trough
digs into the Four Corners region and cuts off a mid-level low. NBM
has shown a slight uptick in token PoPs Tuesday night into Wednesday
as a shortwave trough and associated forcing passes well northeast
of the state. A few ensemble members show low QPF, but not
justifiable to change the forecast at this time, especially with
surface high pressure moving through and continuing to limit
moisture return. The mid-level cutoff low will gradually move
towards the region tapping into Gulf moisture late next week. This
could bring our next chance of precipitation towards Friday or
Saturday as low level thermal lift with some amount of QG forcing
moves toward or over the state.
&&
.AVIATION.../For the 00Z TAFS through 00Z Saturday evening/
Issued at 526 PM CST Fri Dec 8 2023
Main concern will be wind and snow showers north. System southeast
of region clips far southeast with light rain while Saturday
Clipper tracking through MN pulls a cold front southeast. Increasingly
strong winds arrive aft 17z with scattered snow showers aft 20z;
mainly north at MCW. Due to snow shower coverage, have no mention
in terminal but best timing around MCW would be 20z Sat to 00z
Sunday. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION...Ansorge
AVIATION...REV
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
958 PM CST Fri Dec 8 2023
...New MESOSCALE UPDATE...
.MESOSCALE UPDATE...
Issued at 947 PM CST Fri Dec 8 2023
Local radars had a few light showers over the northeast portions
of the CWA with little if any elsewhere. Back northwest of the
ArkLaTex more vigorous convection was firing up. This activity wl
stay to our northwest the remainder of the night but models still
maintain some additional convection in our west after midnight
that may involve a rumble or two due to some elevated instability.
Otherwise, it won`t be as cold tonight as waa increases ahead of
the approaching low pressure system that will bring greater
chances for rain tomorrow. Temperatures were not cooling as fast
in the east as anticipated but morning lows still look achievable.
/22/
&&
.DISCUSSION...
Issued at 234 PM CST Fri Dec 8 2023
Tonight through next Thursday...
Tonight through Sunday: As the shortwave trough ejects east-
northeast, attention begins to turn to more robust mean-longwave
trough along & west of the MS River Valley. 90-120kt jet/increased
forcing/PVA of the strong spoke of energy is progged to round the
trough axis. Mean ridge axis will be amplifying over the
northeast, western Atlantic & subtropical ridge across the
southwestern Atlantic. The combination of the anomalous upper jet
& deepening subtropical ridge/mean ridge axis will help drive a
deeply amplified synoptic pattern. Cold core low over the northern
Plains to Great Lakes will only help strong ascent to occur in
these areas. 1003mb sfc low across the central Plains is progged
to move across the mid-West to Great Lakes by Saturday morning &
deepen to <995mb over south-central Canada through Saturday aftn.
Expect a strong cold front to shift east-southeast across the
Great Plains-Mid West to ArkLaTex by daybreak Saturday & sweep
across the region Saturday evening to overnight hours. Strong WAA
& increased gradient winds are expected as this frontal system
moves through, but some of the later timing should limit some of
the highest gradient wind potential. Lows will be above normal in
the low 60s west of I-55 while mid-upper 50s to the east, with
some patchy fog tonight in the Pine Belt. With highs well above
seasonable values, in the mid-upper 70s, there is expected to be
enough moist advection for dewpoints to climb into the mid 60s &
decent destabilization to occur. Strong low-level jet is progged
to develop, but a majority of that increased low-level flow in the
northern & eastern areas. There is enough progged juxtaposition
of anomalous destabilization & increased mean shear (i.e. ~1500
J/kg MLCAPE & 30-50kts of 0-3km & 0-6km mean bulk shear,
respectively) for all modes of severe weather including a few
tornadoes possible, damaging wind gusts & hail of quarter to golf
ball size. Lapse rates of 6.5-7.0 deg C & vertical totals in the
25-27 deg C range support anomalous destabilization, near
climatological record, for robust updrafts & large hail. Storm
mode at the onset is potentially some supercells transitioning to
broken line/bowing line segments, with embedded tornado potential
highest any east-northeast bowing segments.
Recent high-res CAM runs of the HRRR & RFS have begun to speed up,
with late aftn to early evening across extreme northwest ArkLaMiss
Delta, evening to around midnight across the Natchez Trace to I-55
corridor & late evening to just after midnight for areas east of I-
55. There could be some rogue aftn stronger storm or two that may
have some severe potential, but a majority should be in the late
aftn to evening timeframe. Rain & storm chances, with the best
forcing, have trended earlier but remain pretty isolated southeast
of the Natchez Trace Saturday aftn, but sufficient shear could
support a low end severe threat before the robust activity moves
in. Expect rain & storm chances to quickly scour out through
daybreak Sunday, with majority of the severe potential done
around midnight & any lingering low end potential done around 3AM.
Expect light rain chances to wind down by mid-morning to midday
Sunday. Lows Saturday night will be warmer southeast of the
Natchez Trace in the upper 40s to near 50 degrees due to
rain/storms & gradient wind, while to the northwest into the low
40s. Expect cooler thermo & more blustery conditions Sunday, with
highs 5-10 degrees below normal in the low 50s north to mid-upper
50s south.
Next week (Monday-Thursday): Synoptic/sfc pattern will consist of
mean northwesterly flow/sfc ridging early week gradually
transitioning to more zonal flow & southeasterly return flow &
moderating conditions in the mid-late week. At the start, as sfc
high builds through & winds lighten, widespread lows will fall below
freezing, some +10 degrees below normal, areawide Monday morning &
near to below again Tuesday morning. Widespread frost is expected
during this timeframe each night through mid-morning each day. Highs
will begin to moderate from near 5 degrees below normal in the mid
50s early week to near normal in the low 60s by late week. Lows will
begin to moderate as sfc ridge builds east & southeasterly return
flow commences. With dry conditions aloft & PWs around or less than
half inch, near the 10th-25th percentile, a dry & sunny conditions
are expected through midweek while scattered clouds could build
in late week. /DC/
&&
.AVIATION...
(00Z TAFS)
Issued at 534 PM CST Fri Dec 8 2023
VFR conditions along with VCSH are expected to continue this
evening before cigs lower to MVFR after 06Z and then to a mix of
MVFR/IFR conditions develop by 12Z. These lower conditions wl
continue through 18Z before improving to VFR conditions by 21Z.
A gusty south to southwest wind of 20kts wl be observed at most
TAF sites through the TAF period. /22/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 60 77 44 52 / 20 70 100 10
Meridian 57 77 48 56 / 40 60 100 40
Vicksburg 61 78 43 53 / 20 90 90 10
Hattiesburg 58 78 51 58 / 20 50 100 20
Natchez 61 78 43 53 / 20 70 90 10
Greenville 60 74 41 49 / 50 90 70 10
Greenwood 60 74 41 49 / 50 90 90 10
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
22/DC
Area Forecast Discussion
National Weather Service Marquette MI
717 PM EST Fri Dec 8 2023
.SHORT TERM...(The rest of this afternoon through tonight)
Issued at 133 PM EST FRI DEC 8 2023
Key Messages:
-Warm this afternoon. Some spots may flirt with 50F again,
especially over the west. Some records may also be broken.
-Rain could be seen over the west-central U.P. by early Saturday
morning.
We are already seeing another warm day across our area today as
spots across Upper Michigan have already reported temperatures up to
50F as of 1PM EST. While mostly cloudy conditions will somewhat
limit temperatures from getting much warmer across the central and
east, a hole in the cloud cover currently moving over the western
U.P. (as seen by satellite imagery) will likely increase
temperatures a couple of degrees from what we are seeing as of the
time of this writing. Therefore, there may be quite a few spots over
the western U.P. that get above 50F this afternoon before cloud
cover over northwestern Wisconsin moves in later this afternoon.
Thus, I`m confident (80 to 90% certain) that some high temperature
records will be broken today, particularly over the west.
Expect fairly mild temperatures tonight as mostly cloudy skies
dominate. As a low pressure lifts from the Mid-Mississippi Valley to
Lake Michigan tonight into Saturday morning, we may see some
rainfall starting to fall across our west-central area before dawn
tomorrow.
.LONG TERM...(Saturday night through Friday)
Issued at 431 PM EST FRI DEC 8 2023
Key messages:
- No widespread, significant system snowfalls across Upper MI thru
next week.
- Quick-moving low pressure system brings rain and some snow
Saturday. Snow potential greatest in a narrow swath over a portion
of the west and central U.P., with 1-2" likely and possibly isolated
amounts near 3" but should stay sub-advisory
- 3 to 6 inches of lake enhanced and lake effect snow is likely (at
least 60% chance) for areas favored by nw winds Saturday night into
Sunday, greatest over higher western terrain areas.
- Above normal temps to prevail on most days through next week with
warmth peaking again late next week.
Beginning Saturday, 12z models coming into better agreement on track
of sfc low lifting north through the Central Plains and then across
the eastern U.P. Saturday afternoon. Relatively compact pcpn shield
associated with the wave suggests best pcpn will stay over central
and eastern UP where I will continue with the categorical pops of 80%
or higher with a sharp drop in pops over far western Upper MI where
little system pcpn is expected Saturday. Given the antecedent warmth
over the area, unphased waves and positive tilt of the mid-level
trof, expect most of the pcpn with the first wave to be in the form
of rain on Sat, especially east half. However, CAMs suggest there
could be 1-2" of snow over central portions of Upper MI
(Baraga/western Marquette/Iron/Dickinson counties) and perhaps
higher amounts of 2- 4" in a stronger fgen/deformation band if the
HRRR and NSSLWRF solutions verify. If the stronger band develops
per HRRR and NSSLWRF then travel impacts would also be expected on
Saturday.
To the w, another shortwave will support a sharpening sfc trof that
will sweep into western Upper MI late aftn/early evening. 850mb
temps falling blo -4C will support lake enhancement. Wetbulb zero
heights above 700ft AGL suggest some rain initially at low
elevations near the lake as this next batch of pcpn initially
arrives/develops. Snow will become steadier during the evening as
the trof/wind shift passes. Fcst soundings don`t show much of a
favorable overlap of the upward motion with the DGZ, and that
combined with temps around freezing may hold snow accumulations down
during the period of best forcing in the evening. Still, it`s
looking more and more like a potential of 3-6 inches in the usual
highest terrain areas, greatest west higher terrain where a WSW
advisory may be needed. The trof will shift e thru Sat night,
changing lake enhanced rain/snow to snow east. Accumulations e will
be lower than over the w.
Deeper moisture departs from w to e late Sat night thru Sun morning,
marking a transition to pure nw flow LES under 850mb temps of -10 to
-12C. Fcst soundings indicate the DGZ will be near the top of the
convective layer and largely above the best upward motion, so SLRs
will be held down a bit. With inversions at around 4kft w, LES will
be light. To the e, inversions upwards of 6-7kft will support better
LES and 1-3 inch snow accumulations on Sun. The lingering LES will
end w to e Sun night into early Mon morning with increased ridging
and associated drying/subsidence.
Next shortwave will dive se into northern Ontario and Upper MI Mon
night. WAA/isentropic ascent ahead of this wave should lead to some
-sn developing across the n and e Mon night, followed by wnw flow
LES for Tue as 850mb temps dive toward -16C. Drier air mass flowing
into the area with the CAA will limit LES intensity as will the
quick passage of the 850mb thermal trof, but snow accumulations in
the 1-3 inch range are certainly a possibility. It will be a
blustery day on Tue as well with gusts 20-30mph, perhaps near 40
mph at times over the Keweenaw.
A warming and dry period will set in Wed thru the end of the work
week as westerlies retreat n and ridging takes hold. Warmth should
peak on Thu with high temps back into the low/mid 40s F.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 716 PM EST FRI DEC 8 2023
Flight categories will hover around the MVFR/VFR mark tonight,
moreso VFR at IWD and CMX. SAW, however, will be impacted a bit
sooner as a low pressure system approaches Lake Michigan. All TAF
sites will deteriorate further though during the Sat 12-14Z time
frame as that system moves into the area. Flight retrictions will
be most impactful at CMX and SAW where visibilities and cigs will
dip into the LIFR range. Elsewhere, IWD should stay around IFR. Do
not expect much improvement in this TAF period, but winds are not
expected to be an impact.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 431 PM EST FRI DEC 8 2023
With low pres tracking into northern Ontario, expect southerly winds
20 to 30 knots to becoming sw tonight across Lake Superior. Some
brief gale force gusts are possible from Grand Marais Mi to
Whitefish Pt into early evening. SW winds will settle back to blo
20kt after midnight tonight thru Sat morning. A cold front will then
sweep across Lake Superior late Sat aftn and night, bringing a wind
shift to the nw 20-30kt. There is a 40-60pct chance of low end 35-
40kt gales, with the greatest chc near the MN n shore to across the
tip of the Keweenaw and from Grand Marais to Whitefish Pt. Winds
will slowly subside on Sun with the risk of gales over by midday
Sunday. Expect winds under 25kt late Sun aftn and mostly under 20kt
Sun night. Another cold front approaching on Mon will cause sw winds
to ramp up to 20-30kt by late aftn, strongest w half where low-end
gale gusts could be possible. With passage of the front, there is a
high probability (at least 90pct) of w gales 35-40kt shifting to the
wnw Mon night and Tue.
&&
.CLIMATE...
Issued at 536 AM EST FRI DEC 8 2023
For WFO Marquette in Negaunee Township:
Record high max temp
Dec 8: 44F (1984)
Record high min temp
Dec 8: 33F (2015)
Dec 9: 32F (2015)
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...TAP
LONG TERM...Voss
AVIATION...TDUD
MARINE...Voss
CLIMATE...Rolfson
Area Forecast Discussion
National Weather Service Nashville TN
814 PM CST Fri Dec 8 2023
...New UPDATE...
.UPDATE...
Issued at 752 PM CST Fri Dec 8 2023
Forecast is pretty much on track for this evening. Some light rain
has blossomed across our western counties, as expected, but other
than that, not much going on.
I wanted to talk a little about tomorrow, based on what I`m seeing
in some of the latest CAMs and other models. When I`m looking at
severe potential, I always ask myself, what is going to keep this
from happening? What severe parameter is weak and is going to
stifle tornado development or us getting damaging straight line
winds?
Granted, I`ve been away. I don`t have days of models to go off
of mentally, but looking at the last 3 extended runs of the HRRR
and the 18Z GFS, honestly, I`m not seeing much stifling going on.
If I had to pick one or two: 1) Soundings are saturated. That can
discourage tornado development and downward momentum for wind and
B) Wind profiles are *almost* unidirectional. Neither of these
will negate tornado or damaging wind potential, but they`re worth
pointing out. If anything can keep us from seeing severe weather,
it`ll be morning rain/extra cloud cover to minimize
destabilization.
In a nutshell, I have to continue to agree with the afternoon
forecasters in the potential for all modes of severe weather
tomorrow afternoon and into the early evening hours on the
Cumberland Plateau, to include hail! I don`t think we see monster
hail. That`s not typically a December thing, but forecast sounding
lapse rates suggest we`ll get some hail reports, too. Storm
intensities should drop off pretty rapidly after sunset, so storm
threats should be over by 9-10 pm.
Some may also be wondering about rainfall totals. 24 hours ago, I
know we were talking about 2-3 inches of rain, but latest guidance
has backed off of this considerably. I think 1-2 inches is a good
possibility in several spots, but the flooding threat is
relatively low.
The midnight crew will delve further into the evening suite of
models and have more analysis, but wanted to get some thoughts
going for tomorrow.
&&
.SHORT TERM...
(This afternoon through Sunday night)
Issued at 115 PM CST Fri Dec 8 2023
Latest surface observations shows its a very pleasant December
day thanks to the ongoing strong WAA with temperatures in the mid
to upper 50s on the Plateau and low to mid 60s elsewhere. South
winds have also been quite gusty and reaching the 20-30 mph range
at times, while dewpoints have risen as high as 50 in our
southwest. Moisture will continue to increase the rest of today,
and by 00Z or so scattered showers should break out over our
western counties and gradually spread eastward through the cwa
tonight. Continued WAA will keep temperatures very mild overnight
with lows only dropping into the upper 40s on the Plateau and 50s
elsewhere, which are closer to our normal highs for this time of
year.
Main weather story continues to be potential for severe
thunderstorms tomorrow afternoon/evening as a 100kt H5 jet streak
rounds the base of a positive-tilt upper trough over the Plains
and moves into the Midwest, putting our area in the right
entrance region of the jet streak. As this occurs, a strong cold
front will approach from the west and reach the Tennessee River by
Saturday evening. 12Z models and CAMs have unanimously trended
higher with CAPE and shear tomorrow over the western two-thirds
of the midstate, with peak MLCAPE reaching the 500-1000 J/Kg range
during the afternoon and effective low level shear peaking in the
200-300 m2/s2 range. These values would be favorable for
scattered severe thunderstorms with hail, damaging winds, and
even a couple of tornadoes, with the highest potential for severe
storms along and west of the I-65 corridor between roughly
20Z-01Z. Uncertainty still exists on the degree of severe threat
tomorrow. Some CAMs such as the HRRR are more robust with the
threat and indicate a few supercells are possible during the
afternoon hours across our western half before activity congeals
into a QLCS and moves through our eastern half during the evening.
Other guidance shows less potential for supercells or a more
messy storm mode, leading to a lower severe threat. Regardless,
forecast soundings and ensembles indicate the severe threat will
decrease rapidly after 01-02Z as instability diminishes and a low
level temperature inversion develops, so the severe threat on the
Plateau looks minimal at this time.
After the QLCS moves through, rain is expected to continue across
the area Saturday night into Sunday morning before exiting the
midstate Sunday afternoon. WPC has lowered their forecast QPF,
but overall guidance and WPC still indicate 1 to 2 inches of rain
areawide. Models have trended quicker with moving precip out of
the area, giving less time for cold enough air to arrive and
potentially change the light rain to a light rain/snow mix or
light snow on the Plateau. Could still be a brief window of
opportunity for a little snow on the northern Plateau late Sunday
afternoon or early Sunday evening, and can`t rule out a dusting.
&&
.LONG TERM...
(Monday through next Friday)
Issued at 115 PM CST Fri Dec 8 2023
In the wake of the weekend system, dry weather and colder
temperatures are expected much of next week, with lows in the
20s/30s and highs in the 40s/50s. However, these temperatures are
near or above normal for mid-December. No significant weather is
expected Monday through Thursday, with our next chance of rain
arriving by Friday or Saturday of next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 513 PM CST Fri Dec 8 2023
VFR conditions are expected through most of the night, however as
we near sunrise, cigs should start to drop with the arrival of
scattered showers. MVFR will start the drop, followed by IFR by
mid-morning and these should stick around for the rest of the
period. TS are expected towards the end of the period at CKV.
We`ll see these introduced at the rest of Middle TN terminals in
the next issuance.
Winds will relax for a few hours this evening, but are expected to
get gusty again around 05Z. Southerly gusts of 20-25 kts can be
expected for the remainder of the cycle. Of course, with any
direct impact of TS, winds may be gust higher.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 55 68 40 47 / 50 90 100 50
Clarksville 56 65 37 43 / 50 90 90 20
Crossville 46 60 38 49 / 70 60 100 80
Columbia 55 66 40 46 / 50 80 100 40
Cookeville 51 65 39 47 / 60 80 100 70
Jamestown 47 62 39 47 / 60 70 100 80
Lawrenceburg 54 66 41 47 / 50 80 100 50
Murfreesboro 53 68 39 48 / 60 80 100 60
Waverly 54 65 37 44 / 50 90 90 20
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE.......Unger
SHORT TERM...Shamburger
LONG TERM....Shamburger
AVIATION.....Unger
Area Forecast Discussion
National Weather Service Shreveport LA
942 PM CST Fri Dec 8 2023
...New UPDATE, SHORT TERM...
.UPDATE...
Issued at 932 PM CST Fri Dec 8 2023
No changes with this update aside from adding some maybe severe
wording through late this evening in SE OK and SW AR.
&&
.SHORT TERM...
(Tonight through Saturday Night)
Issued at 932 PM CST Fri Dec 8 2023
The hourly HRRR for so long, all afternoon maybe, had this right
and then gave up just before suppertime as the convection
initiation occurred soon after. Now it is sporting some convection
down Shreveport way in the coming hours. So no changes to pops or
weather, but the time shift past 03Z to 06Z did change weather to
some extent. And now considering the likelihood of this sort of radar
activity for a few hours, just decided to add that wording for
our area with some maybe severe. The SPC has kept with their
marginal risk going and are still are not considering anymore than
20% for watch in their MD. Wind may become a concern as well for
a few hours this evening as the dry line pushes under this lead
short wave. /24/
&&
.LONG TERM...
(Saturday night through next Thursday)
Issued at 345 PM CST Fri Dec 8 2023
By Sunday, a post-frontal airmass will be in place across the Four
State Region. Expect below normal temperatures, as highs will range
from the low to mid 50s across the area. Surface high pressure will
settle across the region by Sunday night. Clear skies and light
winds will set the stage for good radiational cooling, and possibly
freezing temperatures areawide by Monday morning. Expect quiet
conditions to continue through most of the work week under upper-
level ridging, with a gradual warm-up to near normal temperatures.
Afternoon highs will climb into the upper 50s to lower 60s, with
overnight lows in the upper 30s to lower 40s. Could see some clouds
move into the region by mid week ahead of another cool front, which
will bring a return in rain chances by Friday and possibly into next
weekend. /20/
&&
.AVIATION...
(00Z TAFS)
Issued at 541 PM CST Fri Dec 8 2023
For the ArkLaTex terminals, VFR bcmg MVFR this evening with breezy
southerly winds overnight. A lead short wave is edging over E OK
attm and may trigger TS, but N of KTXK/KELD. SFC winds will veer
to S/SW toward daybreak. Overnight speed shear for KMLU should be
our most. Approaching cold front will shift wind to W/NW for our
TX terminals late a.m. through mid aftn with scattered showers
about. We should see TS development by 21Z somewhere b/t KSHV and
KMLU with fropa down our LA I-20 corridor late aftn/early eve. /24/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 66 77 41 55 / 20 40 20 0
MLU 64 78 42 54 / 30 50 60 0
DEQ 58 64 33 51 / 50 30 10 0
TXK 62 70 37 50 / 40 40 10 0
ELD 62 73 37 52 / 40 50 30 0
TYR 64 71 37 54 / 10 20 10 0
GGG 64 74 39 55 / 20 30 10 0
LFK 66 76 41 56 / 20 40 30 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
SHORT TERM...24
LONG TERM....20
AVIATION...24