Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/15/18
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
503 PM CST Sun Jan 14 2018
.Discussion...
Issued at 229 PM CST SUN JAN 14 2018
Pretty solid warm air advection across the area has brought
temperatures to around freezing/melting, mainly across the
southern half of the forecast area. Southwest winds around 10 to
15 mph and good sunshine has allowed for these temperatures to
come up. Areas north of the river will only get to about 25 to 30
degrees this afternoon, but this "warm up" will be very brief as
another very potent cold front is diving south toward the area. By
this evening, around 02z the front will nose into northwest
Missouri. Low level frontogenesis along the surface and low level
front will be responsible for another round of some light snow
later this evening. Mid level ascent associated with the trough
over the Great Lakes will arrive a bit later, so the bulk of the
lift associated with this widespread round of light snow tonight
will be in the lower levels as the cold air moves in. HRRR
soundings taken in the early hours of the event indicate that the
atmospheric profile might struggle to saturate into the Dendritic
Growth Layer, which might lead to some light freezing drizzle
before snow begins to fall once the column saturates. Given QPF
amounts around or less than .10" if any of it falls as light
drizzle it would likely cut into any forecast amounts. The quick
duration of the frontogenetic lift will also limit the amount of
snow production. Right now the forecast calls for about another
inch of snow, give or take a couple hundredths. The quick duration
of the frontogenetic lift will also limit the amount of snow
production.
Behind the cold front, and lasting much longer than the falling
snow, is very cold temperatures, which will overspread the area
through the day on Monday. Temperatures through the day on Monday
will be falling, resulting the high temperature occurring early in
the day. Winds will be in the 10 to 20 mph range, which will bring
wind chill values down to around zero through the day. By Monday
evening/Monday night time frame widespread wind chills will be
down to around 10 to 20 below, with some areas of far northern
Missouri dropping to around 25 below.
Surface ridging will dominate the area for the middle part of the
week, with below normal temperatures and dry conditions. By Friday
a surface trough will form to the west of the area, and mid level
ridging will form ahead of a deepening mid level trough for next
weekend. Good warm air advection ahead of the surface trough will
bring temperatures above freezing for Friday. Warm air advection
continues for Saturday, likely bringing day time highs well above
normal, with temps in the middle 50s. The evolution of the trough
next weekend still bears some watching as confidence is growing
that this trough will eject into the plains and affect the area
with some precipitation. The questions lie with track, timing, and
intensity of the wave as GFS and EC are both still very divergent
in their solutions.
&&
.Aviation...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 455 PM CST SUN JAN 14 2018
Current VFR conditions should quickly transition to MVFR with the
arrival of light snow and reduced ceiling heights through the
latter half of the evening into the early overnight. Snow should
taper off shortly after 06Z, though MVFR stratus will linger until
sunrise. At that point, mixing and resulting gusty winds should
lift ceiling heights slightly through the remainder of the period.
Surface winds will transition to northwesterly in the wake of a
passing cold front.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Winter Weather Advisory from 11 PM this evening to 9 AM CST
Monday for KSZ057-060-103>105.
Wind Chill Advisory from 6 PM Monday to noon CST Tuesday for
KSZ025-057-060-102>105.
MO...Winter Weather Advisory from 11 PM this evening to 9 AM CST
Monday for MOZ007-008-015>017-021>025-028>033-037>040-
043>046-053-054.
Wind Chill Advisory from 6 PM Monday to noon CST Tuesday for
MOZ013>017-020>025-028>033-037>040-043>046-053-054.
Wind Chill Advisory from 3 PM Monday to noon CST Tuesday for
MOZ001>008-011-012.
&&
$$
Discussion...Leighton
Aviation...Welsh
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
931 PM CST Sun Jan 14 2018
.UPDATE...
No major changes needed to the short-term of the forecast tonight, as
the previous forecast is mostly on track. Only changes were made to
the hourly grids based on current trends. 00z guidance is beginning
to come in and a full update to the package will be done tonight
regarding the upcoming winter weather on Tuesday.
&&
.PREV DISCUSSION... /ISSUED 622 PM CST Sun Jan 14 2018/
AVIATION... /00Z TAFS/
SREF cig/vsby probabilities show low probabilities of cigs and vsbys
to build over I-35 through 09z, so will maintain the more-
conservative-than-MOS-guidance trend for another TAF cycle. Light
decoupled evening winds may also play a role in the slow to return
clouds. CIRA-SIMWRF fog product is more agreessive and shows cigs
spreading west rapidy toward DRT by daybreak. Boundary layer moisture
look less saturated at DRT based on the RUC soundings for 10-12Z, so
conditions could potentially drop to lifr there. Once the moist layer
is established will defer to the more pessimistic NAM guidance on an
afternoon return to vfr skies and mid evening return back to mvfr.
PREV DISCUSSION... /ISSUED 250 PM CST Sun Jan 14 2018/
SHORT TERM (Tonight through Monday Night)...
With southerly flow in place temperatures overnight tonight into
Monday will be warmer than we have seen the last few days. Clouds
will also be on the increase overnight and will remain in place
during the day on Monday. Highs Monday will top out in the lower 60s
and will be the warmest temperatures Central Texas will see through
the work week.
Models have trended a bit earlier with the cold front passage with
the NAM, GFS, and ECMWF bringing it into the Hill Country and Austin
area by midnight, Del Rio and San Antonio around 3am, and into the
Coastal Plains by daybreak on Tuesday. Precipitation due to
isentropic lift will be ongoing ahead of the front and will continue
into Tuesday. Temperatures will plummet behind the front. To use
Austin as an example temps will go from the upper 50s Monday evening,
to around 48 at midnight, to 35 at daybreak (behind the front), and
continue dropping into the mid to upper 20s by Tuesday afternoon. See
the LONG TERM discussion below for a more in depth look at the
wintry precipitation forecast beginning Monday Night.
LONG TERM (Tuesday through Sunday)...
Bottom line up front is a wintry mix of precipitation and very cold
temperatures are likely across most of Central Texas beginning Monday
night through Tuesday.
Synoptically isentropic lift and dynamic lift from impulses embedded
in the longwave 500mb trough will help produce precipitation ahead
of the front moving through Monday night into Tuesday and continue
precipitation through the day on Tuesday. Precipitation will linger
into the afternoon hours behind the front but begin to clear from
north to south late Tuesday afternoon and evening. Atmospheric
soundings from the NAM and GFS show precipitation transitioning from
rain to freezing rain and sleet to snow across western and northern
parts of Central Texas. The GFS soundings in these northern area are
more moist in the dendritic growth zone which will favor a switch to
a snow/ice mix across these areas.
This leads to a discussion on precipitation types. Based on the
timing of the front and the strong cold air advection behind the
front the Hill Country and Austin Metro area could see the wintry mix
beginning after midnight and continuing through 6am. This transition
will happen between 6am and noon for San Antonio and the U.S. HWY
90/I-10 corridor, and during the afternoon and evening for the far
southern areas. Initially the mix will mainly be sleet and freezing
rain, but as the atmosphere continues to cool as discussed above some
snow could possibly be mixed in across the Hill Country and Austin
area during the afternoon, and across parts of the Rio Grande plains
during the afternoon and evening. As precipitation exits late in the
day into the overnight hours parts of the coastal plains could also
see some of the wintry mix before precipitation ends.
In terms of accumulations and impacts as of right now we are looking
at possible accumulations of 1/10 of an inch of freezing rain and
sleet with some isolated higher accumulations possible up to 1/4 of
an inch. This does not include any possible snow accumulations,
remaining less than 1/2 an inch, which will again be focused across
the northern and southwestern areas. With this much ice and
temperatures expected to dip down into the 20s Tuesday afternoon the
icing could impact not just the typical bridges and overpasses, but
also primary and secondary roads. This would create significant
travel impacts during the day on Tuesday into Tuesday night as
temperatures remain well below freezing.
Now that we have covered the precipitation expected we do need to
talk briefly about temperatures which will fall through the day on
Tuesday. Model guidance is dropping temperatures by Tuesday afternoon
into the upper 20s across parts of South Central Texas, including
the Austin and San Antonio metro areas. Coupled with the strong north
winds this will create windchill values in the teens for most areas.
These windchill values will continue overnight as lows drop into the
low 20s and upper teens. So after the precipitation ends the cold
will continue to be a concern. This also means that any ice/snow that
does accumulate will stick around through the night Tuesday into
Wednesday morning until temperatures rise above freezing Wednesday
afternoon. There is only a 5 to 8 hour window on Wednesday afternoon
where temperatures will be above freezing before dropping again for
Thursday night.
The GFS and ECMWF are now more in line with one another clearing out
precipitation late Tuesday evening from the Interstate 35 corridor
and out of Central Texas completely by Wednesday morning. Wednesday
will be dry and cold with temperatures slowly rising above freezing
by the afternoon.
Another strong upper level disturbance will approach and move
through South Central Texas Wednesday night and Thursday. With the
cold airmass in place and more precipitation expected, a second round
of wintry precipitation will be possible overnight Wednesday across
the Edwards Plateau and Rio Grande Plains, stretching into the Hill
Country by Thursday morning. The 12z GFS has shifted the focus of
this freezing rain and sleet event further west than previous runs.
Confidence for this second event remains low to moderate as some
differences in the models exist with temperatures and the location
of the wintry precipitation. For now have gone with low end PoPs and
a rain/sleet/freezing rain mix. Of note is the colder trend in the
GFS and ECMWF with temperatures. This would result in a larger area
being impacted by wintry precipitation. Temperatures warm above
freezing by noon Thursday transitioning all precipitation to rain as
the system exits.
Southerly flow returns Friday with dry and warmer weather Friday and
Saturday. The next trough will move across Texas late Saturday into
Sunday dragging a cold front with it. Models are showing slight rain
chances across areas east of Interstate 35 along the front as it
moves through for Saturday night and Sunday.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 42 62 28 29 22 / 0 10 70 60 10
Austin Bergstrom Intl Airport 40 62 29 30 23 / 0 10 70 60 20
New Braunfels Muni Airport 40 63 30 30 23 / 0 10 60 60 30
Burnet Muni Airport 40 58 24 25 18 / 0 10 70 60 10
Del Rio Intl Airport 42 61 34 34 27 / 0 - 60 50 10
Georgetown Muni Airport 40 60 25 27 19 / 0 10 70 60 10
Hondo Muni Airport 41 64 33 33 24 / 0 10 60 60 20
San Marcos Muni Airport 40 63 30 30 22 / 0 10 60 60 20
La Grange - Fayette Regional 40 64 31 31 22 / 0 10 50 50 30
San Antonio Intl Airport 43 62 32 32 25 / 0 10 60 60 30
Stinson Muni Airport 43 64 34 34 26 / 0 10 50 60 30
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from late Monday night through Tuesday afternoon
for the following counties: Bandera...Bastrop...Bexar...Blanco...
Burnet...Caldwell...Comal...Edwards...Fayette...Gillespie...
Gonzales...Guadalupe...Hays...Kendall...Kerr...Kinney...Lee...
Llano...Medina...Real...Travis...Uvalde...Val Verde...Williamson...
Wilson.
&&
$$
Mesoscale/Aviation...Oaks
Synoptic/Grids...Hampshire
Public Service/Data Collection...33
Area Forecast Discussion
National Weather Service Lincoln IL
926 PM CST Sun Jan 14 2018
.UPDATE...
Issued at 926 PM CST Sun Jan 14 2018
Decided to adjust some of the snow totals for tonight. Seeing some
reports already of 1-2 inches so have adjusted snowfall totals up
some with this update.
UPDATE Issued at 909 PM CST Sun Jan 14 2018
Light snow continues to fall across most of central and eastern
Illinois this evening. It is beginning to end just west of I-55 so
there will be a break in the snow late this evening. Then the snow
associated with the main vort max/cold front will move into the
CWA around midnight and then continue overnight. Reports have been
very few, but looks like around an inch has occurred with some of
the heavier pockets. Another 1-2 inches still possible overnight
with round #2. Current forecast is looking fine, but will make
some tweaks and send an update shortly.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 300 PM CST Sun Jan 14 2018
Light snow associated with increasing warm advection ahead of
a weak short-wave trough has developed across west-central
Illinois this afternoon. 20z/2pm radar imagery and area surface
obs suggest snow is falling along/west of a Galesburg to
Jacksonville line. This is a fairly narrow band of precip, with
the snow coming to an end further west across north-central
Missouri. Based on latest HRRR forecast, it appears the snow band
will spread eastward to the Indiana border by early evening...with
the snow tapering off and perhaps temporarily coming to an end
behind the initial band by mid-evening. Given the current dry
airmass and the transient nature of the band, am expecting little
more than a dusting of snow early this evening. The more
significant snow will not arrive until later tonight as a vigorous
wave over South Dakota dives southeastward into the region. Models
have been fairly consistent with their solutions...bringing a band
of light to moderate snow associated with the second wave and its
associated cold front into the NW KILX CWA late this
evening...then spreading it further east and south overnight. NAM
time-height cross-sections indicate a 3-4 hour window of time when
deep-layer omega is maximized and the highest snowfall rates will
be achieved. Despite moderately strong lift and ample profile
moistening, the progressive nature of this system will limit
snowfall totals. Amounts will generally be on the order of 1 to 3
inches...with the highest totals perhaps close to 4 inches focused
north of the I-74 corridor. The snow will linger across the E/SE
through Monday morning before quickly exiting into Indiana by
afternoon. Will be issuing a Winter Weather Advisory for all of
central and southeast Illinois from 9pm tonight through noon
Monday to cover the accumulating snowfall and the distinct
possibility of blowing/drifting snow Monday morning. Strong W/NW
winds in the wake of the system will bring sharply colder air into
central Illinois...with temperatures falling into the single
digits and teens by afternoon.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 300 PM CST Sun Jan 14 2018
Bitterly cold conditions will prevail Monday night as overnight
lows drop to around zero. Thanks to continued brisk northwesterly
winds, wind-chill values will plunge to between 15 below and 20
below zero. As a result, will be issuing a Wind Chill Advisory for
all of central and southeast Illinois Monday night into Tuesday
morning.
With a sharp upper-level trough rotating through the Great
Lakes/Midwest, cyclonic flow will result in plenty of clouds and
perhaps a few snow flurries Tuesday/Tuesday evening before the
trough axis settles southeastward into the Ohio River Valley.
After that, the very cold weather will persist into Wednesday
before the prevailing upper trough flattens and a pronounced
warming trend develops by the end of the week. High temperatures
will climb into the 30s by Thursday...then will soar into the
upper 40s and lower 50s by Saturday. The next significant
weather-maker will not impact the region until late next weekend
when temps will be warm enough to support rain by Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 600 PM CST Sun Jan 14 2018
The waa segment of the clipper system is moving through the area
currently and based on local and mosaic this will last couple more
hours at PIA and BMI. It has already diminished some at SPI/DEC
but has not started at CMI yet. So for these three sites will have
VCSH for this evening with MVFR cigs around 2.5kft at SPI and VFR
cigs at DEC and CMI. MVFR clouds should move into DEC and CMI in a
few hours. PIA and BMI will be MVFR predominately, but IFR vis of
2sm is occurring now with light snow. Have tempo at each site to
cover the IFR conditions. By 05z at PIA and 06z at BMI/SPI/DEC and
07z at CMI, the main wave of snow will begin and there will be
tempo groups at each site for worse conditions of 1sm and cigs
below 1kft. These conditions will improve in the early morning
hours at all sites but VCSH of scattered light snow or flurries
will continue during the morning hours til close to noon. Will
keep MVFR cigs around 2.5kft going at all sites after the snow
ends even into the afternoon. Winds will be southerly this evening
but become southwesterly during the morning hours. Then around
noon, the winds will become west-northwesterly after a cold front
moves through the area...and the associated snow. Will be some
gusts at times through the period around 20kts.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon CST Monday for ILZ027>031-
036>038-040>057-061>063-066>068-071>073.
Wind Chill Advisory from 6 PM Monday to noon CST Tuesday for
ILZ027>031-036>038-040>057-061>063-066>068-071>073.
&&
$$
UPDATE...Auten
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Auten