Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/16/19
Area Forecast Discussion
National Weather Service Bismarck ND
917 PM CST Sun Dec 15 2019
.UPDATE...
Issued at 917 PM CST Sun Dec 15 2019
A thin band of snow moved southeast through Bismarck about an
hour ago and dropped barely enough snow to cover the parking lot
here at the office. Adjusted POPs both south-central and up north
in the Minot area where light snow is moving east. Although
visibilities are still fine everywhere, opted to continue the
patchy fog in the southwest for a few more hours, and slightly
increased the spatial area as well. The latest RAP and HRRR runs
are becoming more insistent on dropping visibilities overnight,
and BUFKIT soundings for points in the far southwest and across
the border into Montana also signal fog development.
UPDATE Issued at 553 PM CST Sun Dec 15 2019
Low stratus deck is overtaking the northern and east-central parts
of the forecast area, with mid-level clouds southwest. Expanded
POPs slightly to the south with Beach reporting snow as of 2330
UTC. Also added in patchy fog in the southwest for the next few
hours, with a few travel webcams showing fog near the ND/MT
border. BUFKIT soundings and high-res model guidance are somewhat
consistent with areas of fog developing overnight, so will keep an
eye on things and possibly expand patchy fog east with the next
update.
&&
.SHORT TERM...(This evening through Monday)
Issued at 150 PM CST Sun Dec 15 2019
A warm front continues to push eastward through the state this
afternoon and a cold front is diving south out of Canada. There
may be a brief period late this afternoon when some clearing
occurs across the southwest, but all areas are expected to once
again fill in with stratus as the cold front quickly advances.
Some real light and brief snow is possible across western North
Dakota this evening as the short-term models show a small area of
mid-level lift associated with the passing wave.
Tomorrow will be a near carbon copy of today with perhaps less
cloud cover.
.LONG TERM...(Monday night through Sunday)
Issued at 150 PM CST Sun Dec 15 2019
Dry and milder weather highlight the extended forecast.
The 12 UTC global suite favors a transition from northwest flow
aloft to mean upper level ridging across the Northern Plains mid
and late next week. Thus a period of above normal temperatures is
expected mid to late next week with widespread highs in the 20s
and 30s, and maybe even a few 40s across the far southwest. This
is also favored by ensembles as well which depict a much higher
than average temperature signal favored through next weekend. At
this point, no precipitation is in the forecast in the extended.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 553 PM CST Sun Dec 15 2019
Widespread stratus across western and central North Dakota with an
IFR cloud deck overtaking northern and east-central ND, and VFR
ceilings southwest. Some scattered light snow is possible
tonight, but low confidence in exact location so only have VCSH at
KDIK/KXWA. Patchy fog is also possible in southwest North Dakota
through the night. Winds will generally be from the west at 5 to
10 knots, increasing to 10 to 15 knots tomorrow afternoon.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...MJ
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...MJ
Area Forecast Discussion
National Weather Service Dodge City KS
450 PM CST Sun Dec 15 2019
...Updated Aviation...
.SHORT TERM...(Today and tonight)
Issued at 300 PM CST Sun Dec 15 2019
Winter weather event Number 1 has come and gone without much fanfare
across southwest Kansas. We had one narrow band of moderate snow
develop and move across the area earlier in the day, but this didn`t
leave any more than around a half inch of snow at any one location.
Round Number 2 is still on the way, and appears to still be on track
for affecting areas mainly south of the Arkansas River to the
Oklahoma border. The last several runs of the HRRR have lined up
fairly well with the other 12Z high resolution model runs, if not
maybe a little bit north closer to the Arkansas River. It all
depends on how far north (if at all) the 700mb baroclinic zone can
push back into southwest Kansas after the first wave pushed it south
a bit. The latest Snow Amount grids will show around an inch of snow
south of a Richfield to Sublette to Greensburg to Pratt line with
around 2 inches from Ashland to Medicine Lodge. We will maintain the
same counties in the Winter Weather Advisory, but we will need to
watch areas like Liberal to Meade and perhaps even Ford County
should the mid level frontogenetic zone shift farther north than
currently expected. All snow should exit the DDC forecast area by
late Monday morning. Temperatures will not rise much above the lower
30s most areas on Monday behind the storm system.
.LONG TERM...(Monday through Saturday)
Issued at 330 PM CST Sun Dec 15 2019
Very quiet weather is forecast the remainder of the week as large
scale high pressure ridging develops across much of the western and
central CONUS. A small upper low will undercut this ridging late
week, but it should pass far enough south such that it will not
impact western Kansas much at all, other than a wind shift.
Temperatures will continue to warm through the week with highs in
the 50s starting Wednesday. The end of this forecast period looks
particularly mild, if not warm Sunday as good downslope conditions
develop, allowing the 700-850mb temperatures to really warm up
across the Central and Northern Plains.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 449 PM CST Sun Dec 15 2019
An upper level wave will move from the four corners region into
southwest Kansas tonight which will drop the cloud ceilings to IFR
conditions for all TAF sites with possible LIFR conditions for
DDC and LBL. Light snow will develop mainly after 03Z for LBL and
surface visibilities will be reduced from 05Z-10Z. Snow showers
could be in the vicinity of GCK and DDC during this time as well
however the snow band from forecast models will be in a narrow
corridor (as a result amendments are possible). As the wave
departs eastward cloud ceilings should rise to MVFR conditions
after 14Z and VFR conditions after 20Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 19 36 17 41 / 40 30 0 0
GCK 19 37 15 41 / 30 10 0 0
EHA 21 37 16 42 / 70 30 0 0
LBL 19 37 14 42 / 70 60 0 0
HYS 15 35 15 41 / 20 10 0 0
P28 20 34 17 42 / 70 70 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Monday for KSZ065-066-
078>081-084>090.
&&
$$
SHORT TERM...Umscheid
LONG TERM...Umscheid
AVIATION...Tatro
Area Forecast Discussion
National Weather Service Hanford CA
206 PM PST Sun Dec 15 2019
.SYNOPSIS...High pressure ridging Monday and Tuesday will keep
weather quiet before another possible storm system impacts Central
California during the middle of next week. High pressure will
return for late in the week with dry weather and a warming trend.
A potentially stronger storm may impact the area next weekend.
&&
.DISCUSSION...Visible imagery shows some upslope low clouds
banked up along the valley facing slopes of the Tehachapi
Mountains and over the far south end of the San Joaquin Valley
while some strato-cumulus is developing over the Sierra
foothills. Skies are mainly clear elsewhere in out area at this
time. Mesowest observations are indicating winds have been
decreasing today after frequently gusting above 45 mph overnight
and this morning across the Kern County mountains and Deserts.
HRRR indicating winds will continue to decrease through this
evening as high pressure builds inland into CA. Temperatures are
generally running 3-6 DEG F below yday at this time as a cooler
airmass settles into the area.
WRF indicating an a dry upper ridge pushes inland into CA. This
will result in skies clearing out and decreased winds across the
area. Radiational cooling in the San Joaquin Valley will allow
for some patchy fog to develop overnight. With lows anticiapted to
be in the mid 30s tonight at most locations areas of frost are
likely although a freeze is not anticipated.
The ridge is expected to continue building inland Monday through
Tuesday. An offshore gradient developing over Socal on Monday
will result in a Santa Ana type wind event Monday night and
Tuesday which might impact Kern County. Later shifts will need to
monitor this situation for possible wind highlights for the
Tehachapi and Fort Tejon areas Monday night through Tuesday
evening. The offshore winds will result in some additional drying
over the area and may allow for temperatures to drop below the
freezing mark at some locations in the San Joaquin Valley if skies
remain clear.
The offshore gradient will decrease by Tuesday night as the next
upper level low pressure system approaches central CA. This
system is progged to move through the area on Wednesday. RH progs
are not showing much moisture with this system and progged QPF`s
are generally very light. Between a tenth and a quarter inch of
liquid precipitation for the central Sierra and just a few
hundredths of an inch at most for the remainder of our area.
The medium range models and their ensemble means are in good
agreement with another dry ridge pushing through CA Thursday and
Friday which will bring another period of dry weather to our area
along with a warming trend. A fairly strong trough is still
anticiapted to impact our area next weekend agreement with a the
models coming into better agreement with a Saturday night to
Sunday time frame as a period of significant precipitation across
our area.
&&
.AVIATION...Areas of MVFR and mountain obscuring IFR in low
clouds over the Tehachapi Mountains near Fort Tejon and Tehachapi
thru 04Z Mon. Areas of MVFR and local IFR in mist over the San
Joaquin Valley between 10Z Mon and 18Z Mon. Otherwise, VFR
conditions will prevail across the Central CA Interior for the
next 24 hours.
&&
.AIR QUALITY ISSUES...On Monday December 16 2019...
Fireplace/Wood Stove Burning Status is: No Burning Unless
Registered in Fresno and Kern Counties. Further information is
available at Valleyair.org
&&
.CERTAINTY...
The level of certainty for days 1 and 2 is medium.
The level of certainty for days 3 through 7 is medium.
Certainty levels include low...medium...and high. Please visit
www.weather.gov/hnx/certainty.html for additional information
an/or to provide feedback.
&&
.HNX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
public...DS
aviation....DS
weather.gov/hanford
Area Forecast Discussion
National Weather Service Wichita KS
603 PM CST Sun Dec 15 2019
.SHORT TERM...(This evening through Monday)
Issued at 216 PM CST Sun Dec 15 2019
Water vapor imagery shows initial impulse lifting across
central/eastern KS with a more pronounced piece of energy
approaching the For Corners region.
Upgraded a few of our northeast counties to a warning a few hours
ago to account for ongoing banded snow along with the potential
for additional snow Mon morning.
Impressive area of banded snow has been ongoing over the last
several hours over northeast into parts of central KS with
numerous snow reports around 6 inches with moderate to heavy snow
still occurring. Even had some lightning show up GLM southeast of
Saline county a couple hours ago. Morning runs of both the NAM
and RAP did a good job showing enhanced area or frontogenesis
along with increased omega in the snow growth region. This area of
enhanced snowfall is expected to be moving out of our forecast
area by around 4 pm. Further south, have had steady freezing
drizzle since early this morning for areas generally south of
Highway 50. This also should slowly diminish as the better low
level isentropic lift shifts east.
Attention then turns to the main vort max which is expected to
move out into the Plains late tonight into Mon morning. Short
range models have come into good agreement in developing another
band of snow across south central KS, generally starting around
3 am. There is good model agreement in some impressive elevated
instability at the onset of the precip, along with good
frontogenesis. So not out of the question to see some
thundersnow/sleet as the initial mid level warm advection moves
into south central KS. There is some differences with the
placement of the heavier snow. The NAM/RAP lift it a bit further
north, more along a Hutch to Marion line, with the GFS/ECMWF more
along a Wichita to Emporia line. So at this point feel confident
enough to increase snow totals after midnight for much of south
central KS into the 2-5 inch range. Snow should decrease from west
to east Mon afternoon with most of it gone by 00z Tue.
.LONG TERM...(Tuesday through Sunday)
Issued at 216 PM CST Sun Dec 15 2019
Upper trough will stretch from the Ohio Valley into the southern
Plains by 12z Tue as upper ridging builds over the western CONUS.
Upper ridging will pass over the area through Thursday with good
agreement between the GFS and ECMWF in a shortwave moving out into
the Plains Fri. With lack of moisture, not expecting this wave to
have much of an impact. We look to get back into a warming pattern
for the weekend as the upper low pushes off to the southeast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 545 PM CST Sun Dec 15 2019
Widespread MVFR and IFR cigs remain across the area in the wake of
the initial shortwave trough. Meanwhile, another robust mid/upper
trough can be seen spinning across the central Rockies. This
system will continue moving eastward emerging across the Central
Plains late tonight and into Monday bringing another round of
snow and a continuation of IFR and MVFR cigs and visibilities to
much of the region. Snow is expected to expand in coverage after
05-07Z and linger across much of south central and east central
Kansas through 20-21Z on Mon. Northerly winds will persist across
the region with speeds in the 10-15 knot range for most areas.
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 21 31 16 39 / 70 80 0 0
Hutchinson 20 31 16 39 / 50 80 0 0
Newton 20 29 16 37 / 50 80 0 0
ElDorado 20 29 16 37 / 50 90 10 0
Winfield-KWLD 22 32 18 41 / 70 80 0 0
Russell 16 32 15 39 / 20 20 0 0
Great Bend 16 33 16 40 / 30 30 0 0
Salina 17 32 15 38 / 30 40 0 0
McPherson 18 31 16 38 / 40 60 0 0
Coffeyville 25 33 20 43 / 50 50 10 0
Chanute 23 30 17 38 / 40 70 20 0
Iola 22 29 16 36 / 40 80 20 0
Parsons-KPPF 24 31 19 41 / 50 60 20 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 PM CST Monday for KSZ032-033-047-
048-050-067>072-082-083-091>096-098>100.
Winter Storm Warning until 6 PM CST Monday for KSZ049-051>053.
&&
$$
SHORT TERM...RBL
LONG TERM...RBL
AVIATION...MWM
Area Forecast Discussion
National Weather Service Lincoln IL
835 PM CST Sun Dec 15 2019
.SYNOPSIS...
Issued at 835 PM CST Sun Dec 15 2019
Snow will continue to impact a large part of central Illinois
through the evening, while it mixes with or changes to freezing
rain near and south of I-70. This precipitation will taper off
after midnight, though some patches of light snow or freezing
drizzle may linger. Monday morning should be dry in many areas,
before the next round of precipitation arrives around midday.
Locations near and south of I-72 will be most impacted by this
second wave of precipitation, which will linger into Monday
evening.
&&
.UPDATE...
Issued at 835 PM CST Sun Dec 15 2019
Winter Weather Advisory was expanded northward to include the
remaining 5 counties in the northern CWA until midnight. Recent
reports around 2 inches have been received in the Peoria area, and
the snow will continue the remainder of the evening there, before
tapering after midnight.
Elsewhere, heaviest snow has occurred from near Charleston to just
south of Springfield, with 4 to 6 inches reported thus far.
Significant forcing occurred in this area earlier, though the
greatest EPV has shifted into Indiana. Latest radar mosaics
showing this same area as the southern edge of the main snow area.
South of that, surface reports near and south of I-70 have
steadily been showing a transition to unknown precip on the
automated obs, which generally indicates sleet or freezing rain
occurring. Last few runs of the HRRR had a good handle on that,
and show this occurring through midnight. Based on forecast
soundings showing a loss of ice crystals after that, freezing
drizzle was added after midnight as far north as I-72.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 255 PM CST Sun Dec 15 2019
Analysis of the progression of the storm through today was shown
by the radar mosaic, with banded pcpn pattern over MO, having
moved into Illinois this afternoon. SPC mesoscale analysis
indicated strong warm advection forcing by 850mb southerly jet
from AR into southern Mo and IL, with very good 850mb moisture
transport. Isentropic lifting therefore significant in the frontal
zone from east central MO into souther central and central IL,
which is expected to continue through evening hours. Banded pcpn
with this system still seems to be significant, with lift enhanced
by EPV forcing shown in SPC mesoanalysis ahead of the 850mb low
in KS.
Moisture channel satellite imagery continued to define the main
upper jet axis across northern MO into northern IL. Jet axis north
of the main low level frontal zone and serving to enhance the
lift of the warm advection, isentropic lift. Loop of the IR
imagery has been depicting development zone of the pcpn over
central MO and this area advected into IL. This trend of banded
snow development should be the main focus through evening hours.
Satellite also shows the back edge of mid level short wave from
eastern NE into northern central OK. Movement eastward will
continue on this feature, as it reaches IL overnight, and finally
ends the pcpn by morning.
Then, before the next system, there will be a lull through much
of the day on Monday. The next system is more upper level dynamic
driven, as the main upper short wave trough is progged to move
through. Difference in today`s model forecast is the low level
boundary by Monday will be farther southeast and so when the upper
level system moves through Monday afternoon, the amount of lift
will be weaker and the tap of moisture will be more limited. Snow
amounts with that system will be less.
With the ongoing pcpn impacts expected, will keep the current
warnings and advisories going and as conditions warrant, they
will be updated appropriately.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 255 PM CST Sun Dec 15 2019
Pcpn continuing into the overnight hours, ending by Tuesday
morning.
Rest of forecast period is dry.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 534 PM CST Sun Dec 15 2019
Mosaic radar display continued to show banded snow in east-west
orientation over central IL in the strong warm advection pattern
over region. SPC analysis continued to show the strong isentropic
lift region, with upper shortwave gradually advecting east over
western IA. Cigs and Vsbys are extremely variable in the banded
pcpn pattern, with IFR conditions when a heavy snow area moves
through and then some improvement in Vsbys after it passes. TAFs
reflect variability. Models continue to move snow development
region to the east later tonight, keeping the cigs down in the IFR
category. Next wave on Monday afternoon, brings Vsbys down again
in southern TAF sites, but not as strong as with this first wave.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight CST Monday night for
ILZ036>038-040>048-071>073.
Winter Storm Warning until midnight CST Monday night for
ILZ049>057-061>063-066>068.
Winter Weather Advisory until 6 AM CST Monday for ILZ027>031.
&&
$$
UPDATE...Geelhart
SYNOPSIS...Geelhart
SHORT TERM...Goetsch
LONG TERM...Goetsch
AVIATION...Goetsch
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
930 PM CST Sun Dec 15 2019
.UPDATE...
Issued at 915 PM CST Sun Dec 15 2019
I have made some big adjustments to the forecast for Monday.
In the short term the tonight period is evolving pretty much as
expected. The coverage of snow continues to diminish this evening
across the northern CWA as forcing shifts to the east with the
translation of a weak low amplitude short wave, and any
additional snow accumulations will be quite light this evening.
This area will eventually see a loss of cloud ice overnight and
transition to freezing drizzle with light glazing possible.
Further south we have already lost cloud ice across most of the
area along and south of I-70 and thus freezing drizzle will
dominate the remainder of the night with light glazing expected.
The new 00z NAM and at least the last 3 runs of the RAP are now
indicating much higher snow totals on Monday. An impressive
deformation zone is expected to evolve in response to large scale
forcing for ascent associated with a impressive migratory short
wave, strengthening mid level frontogenetic forcing, and
divergence within the entrance region of an ULJ streak. This band
should evolve during the morning and strengthen thru the
afternoon spreading from southwest/south central MO along a Rolla-
St. Louis-Litchfield line. Snow should exit to the east during
the evening. Snowfall rates within this band will approach an inch
per hour at times. I think additional snow accumulations with the
band will be in the 3-5 inch range along the aforementioned axis
centered through St. Louis. No changes to headlines are warranted
at this time.
Glass
Issued at 727 PM CST Sun Dec 15 2019
I have made a quick update for this evening to account for the more
persistent narrow snow band currently extending from near
Wellsville MO through Kampsville to Palmyra IL. This band is
likely producing rates up to an inch an hour. I think it will
persist another hour or two gradually pulling east-northeast and
weakening. Storm totals within the vicinity of this band could be
in the 6-8 inch range.
Along and south of I-70 the loss of cloud ice has brought an end
to measurable snow tonight and freezing drizzle should be the
predominant ptype with light ice accumulations.
Glass
&&
.SHORT TERM... (Through Late Monday Night)
Issued at 331 PM CST Sun Dec 15 2019
Early this afternoon, a very broad-based TROF extended over much of
the CONUS with a W-SW flow aloft/WAA regime over our region. The
strong storm system that we have been watching carefully was near
the Four Corners region in the southwest CONUS. At the surface,
an area of high pressure was centered over northern Illinois and
central Indiana with easterly flow over our region. A developing
surface inverted TROF was poking into southwest MO. Skies were
overcast across our region. Of most note was the heavy snow band as
forecast, but this has now drifted through much of the I-70 corridor
and is looking to settle a bit more in position through early this
evening. Temperatures were in the 20s for areas near and north of I-
70 and into the low 30s for areas south of I-70.
The WAA snow, locally enhanced by strong frontogenesis with that
heavy snow band just north of I-70, will gradually exit this evening
being replaced by a regime exhibiting a loss of cloud ice and weak
WAA. In addition, the inverted surface TROF will track east across
Missouri and southern Illinois and should create low level
convergence to develop areas of freezing drizzle for much of
tonight. This will continue into early Monday morning.
The main system is still expected to track E-NE through the main
flow and approach and move by our region later on Monday and into
Monday night. Lift will deepen, restore cloud ice to much of the
area, and result in an expansion of snow later on Monday morning and
continue through Monday evening before finally pulling out. The
best areas for additional snow accumulation look to be near and
north of I-70 with a snow/freezing rain scenario continuing for
areas further south. The upper level LO tracks continue to favor
what looks to be an additional 2-3" of snow possible for many of the
same areas affected by the heavy snow band today.
Between the already fallen/expected snow accums and forecasted ice
accums, much of the Warning/Advisory stratification looks justified
and will continue with this issuance.
TES
.LONG TERM... (Tuesday through Next Sunday)
Issued at 331 PM CST Sun Dec 15 2019
The weather still looks relatively quiet for Tuesday through next
Sunday. Cold temperatures are still expected Tuesday and Wednesday
as a cold high pressure system builds into Missouri and Illinois
behind the storm...especially Tuesday night when light wind, fresh
snow and clear sky will produce excellent radiational cooling
conditions. Highs mainly in the low to mid 30s and lows in the
teens to low 20s continue to look reasonable. Wind turns back to
the south on Thursday as high pressure moves into the Ohio Valley
and further east. Widespread highs in the 40s with even some low
50s in southeast Missouri look likely with lows mainly in the 30s.
There`s still a possibility of a little rain on Friday. The ECMWF
and GFS are in good agreement that a shortwave trough will move from
the Great Plains through the Midwest Friday into Friday night.
However, the GFS has a more progressive trough than the EC does.
It`s also been consistently printing out very light QPF ahead of the
trough, while the ECMWF has been alternating dry-wet-now dry again.
Am keeping the forecast dry at this time as the QPF that the GFS
prints out is very light and will likely have little or no impact
even if it does rain. Saturday and Sunday continue to look dry with
highs in the 40s and lows in the 30s.
Carney
&&
.AVIATION... (For the 00z TAFs through 00z Monday Evening)
Issued at 542 PM CST Sun Dec 15 2019
Poor flight weather is expected across the region through the
period. Along and axis from KCOU to the St. Louis metro there
could be a mix of ptypes for the first part of this evening
including -SN, -IP, and -FZDZ however the tendency as the evening
progresses should be for predominately freezing drizzle producing
light ice accumulations. At KUIN, snow will prevail until around
mid evening and the tendency should be for freezing drizzle as
well. Another round of snow will spread across the area on
Monday morning. Flight conditions will be dominated by IFR across
the region.
SPECIFICS FOR KSTL:
Poor flight weather is expected across the region through the
period with IFR flight conditions dominating. There could be a
mix of ptypes for the first part of this evening
including -SN,-IP, and -FZDZ however the tendency as the evening
progresses should should be for predominately freezing drizzle
producing light ice accumulations. Another round of snow will
spread into the terminal around 14-15z Monday morning.
Glass
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Winter Weather Advisory until midnight CST Monday night for
Crawford MO-Iron MO-Knox MO-Lewis MO-Madison MO-Marion MO-
Reynolds MO-Saint Francois MO-Sainte Genevieve MO-Shelby MO-
Washington MO.
Winter Storm Warning until midnight CST Monday night for Audrain
MO-Boone MO-Callaway MO-Cole MO-Franklin MO-Gasconade MO-
Jefferson MO-Lincoln MO-Moniteau MO-Monroe MO-Montgomery MO-
Osage MO-Pike MO-Ralls MO-Saint Charles MO-Saint Louis City
MO-Saint Louis MO-Warren MO.
IL...Winter Weather Advisory until midnight CST Monday night for
Adams IL-Brown IL-Randolph IL.
Winter Storm Warning until midnight CST Monday night for Bond IL-
Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL-
Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL-
Pike IL-Saint Clair IL-Washington IL.
&&
$$
WFO LSX
Updated for 00Z Aviation Forecast Discussion below.
&&
.PREV DISCUSSION... /issued 314 PM CST Sun Dec 15 2019/
DISCUSSION...
A potent trough continues to take shape over the Southern Rockies
this afternoon. Mid-level height falls are spreading eastward into
the Plains aiding in the development of a surface cyclone along a
stationary front in central TX. The cold front that moved through
the Mid-South yesterday is now lifting poleward across north MS
as a warm front. Analysis as of 3 PM places this front from near
the Interstate 40 corridor. Warm sector dewpoints are creeping
back into the 50s with temperatures approaching 60F in a few
areas. North of the front, temperatures are mainly in the 40s.
Strong, quasi-zonal flow aloft will gradually become more
southwesterly through tomorrow as the trough approaches. The
attendant upper-tropospheric jet will begin to shift to the east
tonight, placing the Mid-South in the right entrance region, a
favorable location for forced ascent. We`ve already seen scattered
light radar returns in the warm sector but rain and drizzle will
continue to develop north of the warm front as moist, isentropic
ascent continues over the frontal zone. Light rain may be
widespread north of I-40 by sunset and will continue through the
overnight hours as the warm front stalls. Some elevated
instability will be present late tonight and may support a few
rumbles of thunder.
As the trough approaches the region tomorrow, the TX surface low
will zip northeastward along the stationary front. This will
maintain the warm sector over northeast MS (and possibly into
extreme southwest TN) as southerly winds continue east of the
surface cyclone. Instability is forecast to increase in the warm
sector with MLCAPE peaking between 500-1000 J/kg tomorrow
afternoon. Shear will be quite strong across the region with long,
cyclonically curved hodographs. There remains a potential for
some strong to severe storms, mainly during the afternoon hours
across north MS, while the threat will be minimal north of I-40.
The primary hazard will be damaging wind, but there is also a
threat for large hail and a tornado or two. CAM ensemble guidance
continues to show the most significant updraft helicity swaths
south of the CWA, perhaps as far north as Tupelo.
Post-frontal rain will end from west to east Monday night as the
upper-level trough axis crosses the region. There is a brief
window where some lingering light rain could mix with light snow,
but it shouldn`t amount to anything as it quickly ends before
sunrise. A cool and dry air mass will settle over the region
Tuesday with temperatures in the mid 40s. Shortwave ridging aloft
will promote light winds and clearing skies, setting the stage
for a chilly Wednesday morning. Expect lows in the low/mid 20s in
most areas. We`ll otherwise see a nice weather period midweek as
the dry spell continues through Thursday night. Temperatures will
moderate back into the lower 50s for highs and 30s for lows, which
is pretty close to climatology for mid- December.
A progressive trough will move across the region Friday into
Saturday, providing another chance of rain for the Mid-South. QPF
doesn`t look impressive with this system and dry weather should
return by Saturday evening. Medium range models indicate some
upper-level ridging Sunday into early next week. This should
provide for a quiet start to the work week with temperatures on a
slow warming trend.
MJ
&&
.AVIATION...
00Z TAFs
Weak surface front along a MEM-MKL line will sharpen up this
evening, with influx of additional maritime moisture. KGWX VAD
wind profiler showed FL030 winds from 210 degrees at 65 to 70
knots just prior to 00Z. Despite clearing noted on GOES IR
imagery lifting into north MS, expect the maritime air to cloud up
at least a bit through the evening.
Regarding TS chances, HRRR and NAM 3km convection-allowing models
(CAMs) did not depict much in the way of TS overnight, while GFS
LAMP guidance painted a broad swath of 40 to 50 percent chance TS
through MEM and MKL. For the 00Z TAFs, have left VCTS in overnight
- but with lower than normal confidence. Main impact will be LLWS,
associated with the aforementioned FL020 winds.
PWB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Nashville TN
830 PM CST Sun Dec 15 2019
.DISCUSSION...
Rain event is underway as strong WAA has commenced over our area,
with a warm front now having moved northward to near a Waverly to
Livingston line. Warm front should continue northward but stall
near the KY border before oscillating back and forth over our
northern zones through the day tomorrow per HRRR model. Showers
that developed earlier over our northwest counties continue to
increase in coverage and intensity, and GFS forecasts K-index
values to rise well into the 30s in the next couple of hours.
Thus anticipate some thunderstorms to develop over our northwest
zones as well. Rain and thunderstorms should continue to focus
near and on the cool side of the stationary boundary tonight into
tomorrow, leading to an southwest to northeast axis of heavy
rainfall somewhere over our northwest half. Exactly where this
axis sets up remains somewhat in question as models continue to
differ with placement from north to south, with NAM furthest
north and GFS furthest south - but model consensus shows the most
likely scenario to be a swath of 1 to 3 inches of rainfall in the
vicinity of a line from Linden to Nashville to Westmoreland. Some
flooding will be possible along this axis of heavier rainfall on
Monday, especially in the afternoon and evening, when rainfall
rates are heaviest. Have adjusted temps and pops based on this
latest forecast reasoning, radar trends, and surface obs.
Concerning the severe potential, models are keeping most of the
warm sector free from thunderstorm activity until very late
tomorrow afternoon and mainly tomorrow evening when the main
surface low ejects northeastward across our area. With the low
track bisecting Middle Tennessee, main severe weather threat will
remain off to our south across Mississippi and Alabama, but
cannot rule out a strong or severe thunderstorm across our far
south and east counties. MLCAPE will struggle to reach 500 J/Kg in
our area, but low level and deep layer shear will be extremely
strong, so a few storms could contain damaging winds and hail.
This is true even along the cool side of the stationary front due
to considerable elevated instability. If enough instability can
make it this far north, an isolated tornado is not out of the
question in our far southern and eastern Middle Tennessee, but
this remains questionable. The midnight shift should get a better
handle on the severe weather threat as the full suite of CAMs
comes into range overnight.
&&
.AVIATION...
00Z TAF DISCUSSION.
BNA/MQY/CKV...VCSH has already started with VFR skies. Expect
skies to become MVFR by 03Z. Gusty westerly winds of 15-20 kts
expected through the night and becoming southerly. -DZ should
begin around 03Z for CKV and -SHRA after 06Z for BNA and MQY. Also
expect LLWS from 06Z-15Z. By sunrise CIGs will become IFR/LIFR as
the rain increases in intensity. Also including some -TSRA after
21Z.
CSV...VFR conditions...it will take some time for the showers to
reach the terminal in the east and have this happening after 05Z
when CIGs become MVFR. Winds will be southerly and gusty 10-20kts.
Also expect LLWS from 06Z-15Z. As the cold front sweeps through
tomorrow IFR/LIFR conditions expected along with -TSRA.
&&
.PRELIMINARY POINT TEMPS/POPS...
Nashville 52 61 37 42 25 / 90 100 100 10 0
Clarksville 45 50 34 41 24 / 100 100 100 10 0
Crossville 47 62 40 41 22 / 50 100 100 30 0
Columbia 54 65 37 43 25 / 90 100 100 10 0
Lawrenceburg 54 67 39 44 25 / 70 100 100 10 0
Waverly 49 54 35 41 25 / 100 100 100 0 0
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......Shamburger
AVIATION........12
Area Forecast Discussion
National Weather Service Pocatello ID
140 PM MST Sun Dec 15 2019
.SHORT TERM...Tonight through Wednesday. Early afternoon satellite
imagery was showing low clouds throughout the Snake River Plain and
Eastern Magic Valley as a broad disorganized trough advanced through
the region. Light snow was noted in the Missoula area as a weak
disturbance rotated SE through the panhandle on the WRN periphery of
the aforementioned trough. The numerical models continue to show some
light seeder-feeder snowfall within the Snake River Plain and ERN
mountains tonight (although not as robust as previous model runs) as
that disturbance shears SE through the region. Additional weaker
disturbances follow Monday afternoon/evening while a ridge of high
pressure expands along the NW coast. We should see progressively
drier/clearer conditions work into the region Tuesday and Tuesday
night as the ridge builds inland. The clearing will promote strong
radiational cooling and well below normal temperature`s Monday
through at least Wednesday morning with some recovery Wednesday
afternoon as the flow aloft becomes more southwesterly ahead of the
next incoming Pacific storm. Huston
.LONG TERM...Wednesday night through next Sunday. A moist, westerly
flow remains on tap following Wed`s dry trough passage. The Canadian
model initiates precip into the Central Mntns much earlier (Wed eve)
than the GFS/ECMWF (midday Thurs), and we considered it an outlier.
Continued to run with the reasonable NBM solution, which spreads
snow showers across the forecast area late Thurs AM into the
afternoon. Once again, the flow will target the higher-elevation,
west-facing slopes for greatest accumulation, but this still isn`t
looking like a major event. Even looking at the NAM 75th percentile
on 48-hour accumulation Thurs/Fri, most of the CWA picks up almost
nothing, and the Central Mntns west of Challis/north of Hailey stay
under 1 foot. AND, the long-range models are a bit more progressive
in shutting off that moist flow with a building longwave ridge of
high pressure by Fri night. Snow showers at lower elevations and in
the Snake Plain may end up being pretty light and hit-and-miss. So,
at this time, nothing looks particularly high impact outside of the
Central Mntns as we finish out the week. Dry conditions are now
expected Sat/Sun, with the region largely under the influence of the
ridge. Temps look to increase a few degrees each day through the
latter part of the week, trending a bit above climatological norms
for this time of year. - KSmith
&&
.AVIATION...The main concern for aviation over the next 24-48 hours
will be continued low stratus and patchy fog due to a very moist,
post-storm low-level airmass. Generally MVFR cigs are expected to
continue throughout the afternoon/eve, with almost no guidance
lifting anything above 3,000 feet. Given the continued low-level
saturation and lack of significant wind or any new system to clear
things out, this makes perfect sense. Stratus should again intensify
and lower tonight, probably back into IFR at KPIH/KIDA, and perhaps
KDIJ (less confidence there), supported again by very light winds
and the recent snowfall. We again used a combination of MOS guidance
and the HRRR cig/vsby products to develop our cigs and FG/BR
expectations in the TAFs (with the LAMP and the auto-generated MOS-
based TAF guidance used as a sanity check). They aren`t always
right, but they have been doing well at capturing the flavor of
things in these recent post-storm airmasses, and the degree of
moisture running around right now makes the NAM time-heights and
even some of the BUFKIT soundings nearly useless. Once again, we
expect the stratus to be the greater issue, with fog more patchy due
to the insulating cloud cover above. The greatest potential for LIFR
and near-closure conditions exists at KIDA, especially after 11-12z.
Meanwhile, KSUN should remain VFR for cigs/vsbys throughout the next
48 hours.
We do have a weak shortwave dropping across the region this
afternoon/tonight, and some of the coarser, deterministic model
projections do generate some snow shower/flurry activity with this.
It stands to reason that any mid-level clouds associated with this
feature (some observed upstream on satellite) moving over the low
stratus could contribute ice nuclei to the lower deck and set up a
seeder-feeder process. However, most of the high-res guidance
(particularly the HREF ensembles) are fairly dry, so our confidence
in snow showers hitting a given terminal is extremely low. Blanketed
the TAFs with VCSH for now, and will make any needed adjustments
based on radar/observational trends. - KSmith
&&
.PIH WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
...Update to aviation forecast discussion...
.SHORT TERM...(This evening through Monday night)
Issued at 340 PM CST Sun Dec 15 2019
Snowfall should gradually end from west to east late this
afternoon and evening as isentropic upglide and frontogenetical
lift cease with increasing northerly flow through the column.
Current radar trends still show elevated CSI being realized as
banded snow from Dickinson to Jackson counties. These bands should
decay from west to east with the loss of forcing. CAM guidance
and short-term trends are in very good agreement in the snow
coming to an end across the entire area by 9pm, which is the end
time for both the northern Winter Weather Advisory and the Winter
Storm Warning. Overall snow amounts have been coming in at around
3 to 6 inches, with localized amounts over 8 inches being reported
as well.
A brief lull in the snowfall will continue for most of the
overnight hours with subsidence occurring until the second round
begins in east central KS a few hours before sunrise. This next
batch comes ahead of the main trough axis swinging through western
KS, and the CVA associated with this wave looks to be the main
driver of this phase of the event as the baroclinic zone pushes
south and east of the area, taking the frontogenetical forcing
with it. Any cloud ice that would be lost this evening should be a
non-issue for Monday due to the DGZ re-saturating once we get
forcing for vertical motion in the morning. As such, have kept all
snow through the day with the highest chances along and south of
a line from Topeka to Council Grove. Models still vary slightly as
to how far north we`ll see any snow, so it`s possible Topeka
stays dry completely. Regardless, the northern half of the CWA
should avoid this round of snow with east central KS expected to
see it taper off in the evening as lift and saturation both
decrease. Additional accumulations look to be another inch or two
with potentially some locally higher amounts as the 18Z HRRR has
hinted at some more narrow bands developing tomorrow.
Have trended high temperatures a bit cooler in eastern KS for
tomorrow, in part because of the CAA regime expected to dominate
the period, and also to account for the new snow pack in east
central KS in particular. Most areas are forecast to stay in the
upper 20s with north central KS reaching the low 30s, where snow
amounts have been lower. With clouds clearing overnight after the
system moves out, lows are forecast to drop to the teens area-
wide.
.LONG TERM...(Tuesday through Sunday)
Issued at 340 PM CST Sun Dec 15 2019
Dry weather is expected for the rest of the week as ridging
builds in behind the Monday system. Another mid-level trough does
look to deepen to our west on Thursday and pass south of the area
on Friday, but precipitation is forecast to remain south at this
time with our only impacts being increased cloud cover and breezy
southerly winds. Temperatures are still dependent on snow pack and
how quickly it melts under sunny skies, especially on Tuesday,
but a general warming trend is expected late in the week with WAA
returning late Wednesday into Thursday. If this trend verifies,
more seasonal temperatures in the 40s would return for the second
half of the week, if not slightly above average.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 539 PM CST Sun Dec 15 2019
Conditions improving somewhat with snow moving east, though MVFR
ceilings should persist for much of this forecast. Confidence in
the next round of snow reaching the terminals is too low for
restrictions with it.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 PM CST this evening for
KSZ009>012-021-034.
Winter Weather Advisory until 6 PM CST Monday for KSZ040-054>056-
058-059.
Winter Weather Advisory from 3 AM to 6 PM CST Monday for
KSZ022>024-026-035>039.
Winter Storm Warning until 9 PM CST this evening for KSZ022>024-
026-035>039.
&&
$$
SHORT TERM...Picha/Skow
LONG TERM...Picha
AVIATION...65