Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/07/18

Area Forecast Discussion

National Weather Service La Crosse WI

 1022 PM CDT Sat Oct 6 2018

.SHORT TERM...(This evening through Sunday)
Issued at 345 PM CDT Sat Oct 6 2018

At 3 PM, the surface cold front extended from southwest Lower
Michigan into central Missouri. Temperatures south of this front
were in the 80s and lower 90s. Meanwhile north of this boundary
the temperatures ranged from the mid-40s to the 50s. Along this
front, there was scattered showers and storms. A few of these
storms were severe.

For tonight, the 06.12z models show that a short wave trough will
move northeast through southeast Iowa and northern Illinois. Much
of the 850 mb moisture transport ahead of this system remains to
our south and southeast. The greatest values (1000 to 1500 J/kg)
of most unstable CAPES remain across northern Missouri, central
Illinois, and central Indiana. After 07.10z, the RAP has up to
200 J/kg across portions of northeast Iowa and southwest
Wisconsin. This instability along with synoptic lift and weak
ascent from the upper level jet will result in the development of
scattered showers. The highest rain chances will be after
midnight south Interstate 90.

On Sunday, the upper level trough will continue to gradually
deepen to our west and the upper level ridge will retrograde
slightly to the west into the Tennessee River Valley. This will
gradually increase the southerly flow aloft. As this occurs, the
warm front will move slowly north across northern Missouri and
southern Iowa. As the instability is lifted up and over the warm
front, showers will move northward into the area. There may be
even a few isolated thunderstorms by late afternoon.

.LONG TERM...(Sunday night through Saturday)
Issued at 345 PM CDT Sat Oct 6 2018

On Sunday night and Monday, the warm front will gradually move
northward through the area. Precipitable water value will climb
to around 1.50 inches which is close to 200 percent of normal and
warm cloud layer depths will be around 3.5 km. This moisture then
remains over the area through at least Wednesday morning. There is
still some uncertainty on far north the warm front will get on
Monday night and how fast will the cold front move east from
Tuesday into Wednesday. The entire area will likely see 1 to 2
inches from Sunday night into Monday. Another 1 to 3 inches looks
likely from Monday night into Tuesday night along the cold front.
Thinking that the highest totals will be near Interstate 35, but
concerned that it could be a bit further east if the NAM verifies.

On Wednesday, the models continue to differ on the intensity and
timing of a negatively tilted trough moving through the region.
The ECMWF and GEM are much stronger with this wave and as a result
they have stronger shear and a higher potential for severe
weather. Meanwhile, the GFS is much weaker with this system and
there would likely be no severe weather.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1022 PM CDT Sat Oct 6 2018

Stratus holding firm across the area as expected, with mainly MVFR
ceilings likely to remain intact overnight and really right on
through the next 24 hours. Should see ceilings gradually lower
into Sunday afternoon as moisture starts to increase, with
widespread IFR and even LIFR conditions developing later in the
afternoon and evening as a large shield of rain overspreads the
area. Winds will be from a north to northeasterly direction
overnight, shifting due east through the day and into Sunday
evening at 5-15 knots, strongest of course at RST.

&&

.HYDROLOGY...
Issued at 345 PM CDT Sat Oct 6 2018

From Sunday night through Wednesday, there be several rounds of
showers and storms. With well above-normal (about 200 percent)
precipitable water values and warm cloud layer depths, there will
be periods of moderate to heavy rainfall. Much of the area will
see anywhere from 3 to 4 inches with locally higher amounts. Due
to some uncertainty on the timing and location of heaviest rain
bands, opted to issue an Excessive Rainfall Outlook for now. As we
get closer to this time period, we will likely have to issue
Flash Flood or Flood Watches for all or parts of this time period.

&&

.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&

$$

SHORT TERM...Boyne
LONG TERM...Boyne
AVIATION...Lawrence
HYDROLOGY...Boyne




Area Forecast Discussion

National Weather Service Indianapolis IN

 1140 PM EDT Sat Oct 6 2018

.UPDATE...
The AVIATION Section has been updated below.

&&

.SYNOPSIS...
Issued at 329 PM EDT Sat Oct 6 2018

A warm and humid environment will be in place across central
Indiana through the weekend and into next week. A persistent
frontal boundary will remain in the area with central Indiana on
the warm side making the environment very conducive to diurnal
development. Some of the storms could become strong to severe this
evening and tonight. The pattern will then change around mid-week
when a strong cold front moves through the forecast area on
Wednesday night. This will result in an abrupt change from the
summer like weather back to more normal Fall temperatures late in
the extended period.

&&

.NEAR TERM /Overnight/...
Issued at 958 PM EDT Sat Oct 6 2018

Convection from earlier this afternoon and evening has diminished
leaving central Indiana dry as of mid evening. The cold front has
drifted back south in wake of the earlier storms...and is now as
of 02Z located from Vermillion County northeast to southern Howard
County. Low clouds...northwest winds and noticeably cooler
temperatures in the lower 60s existed north of the boundary...
while the rest of the area ranged from the upper 60s to the mid
70s.

Some changes need to be made for the overnight considering the
front is further south than originally thought. In addition...hi-
res guidance has been extremely poor in handling convection today
and tonight...with low confidence in much more substantial impact
from rain and storms the rest of the night...even closer to the
front. HRRR is now bringing the front all the way down to within
about 10-15 miles of I-70 overnight before pulling it back north
during the predawn hours as heights aloft rise. Weak disturbances
riding around the upper level ridge were contributing to scattered
convection across Missouri this evening and as these move
northeast overnight...could see a slight uptick in convective
coverage over primarily the northern Wabash Valley. With minimal
instability and plenty of CIN already noted over the region via
mesoanalysis...have a hard time justifying much more than 20-30
pops for northern counties for the rest of the night.

As for the front...temps...winds and cloud cover will all be
impacted by how far south the boundary can get before retreating.
Have nudged temps down a few degrees over the northwest third of
the forecast area and bumped up cloud cover substantially with an
abundance of very low stratus present north of the front. As the
front pulls back north overnight...may see temps bump back up in
some locations northwest of Indianapolis. Over the southern half
of the forecast area...expect dry weather overnight with warm and
muggy conditions continuing.

Zone and grid updates out.

&&

.SHORT TERM /Tomorrow through Tuesday/...

Issued at 329 PM EDT Sat Oct 6 2018

Much of the same can be expected for tomorrow. Central Indiana
will remain in a warm, moist environment with southerly flow. Once
again, the best chances for any showers and thunderstorms will be
over the northwest two-thirds of central Indiana...closest to
frontal boundary. Meanwhile, the southeastern third of central
Indiana can expect mainly dry conditions. However, the drier air
will start working its way northward on Sunday night as the high
pressure over the Delmarva/Southeast U.S. shifts a bit. So, expect
dry conditions over all of central Indiana by Mon 06Z.

Monday and Tuesday, the high temperatures in the mid to upper 80s
will continue with dewpoints in the 60s. With the aforementioned
frontal boundary a little farther north though, shower and
thunderstorm chances will be reduced across most of the forecast
area. The exception will be low chances across the northernmost
counties.

&&

.LONG TERM /Tuesday night through Saturday/...
Issued at 256 PM EDT Sat Oct 6 2018

Models and ensembles in reasonable agreement that a strong cold
front will move through Wednesday night. Very warm, moist and
unstable air along and ahead of the system combined with the strong
dynamics will bring widespread showers and thunderstorms to the area
next Wednesday and Wednesday night. Heavy rain will be possible.

After that, the well above normal airmass will be replaced by a
below normal one for late next week and weekend.

There will also be a threat for more showers, but models and
ensembles are not in good agreement with the timing, so will accept
the blend with low confidence in timing. Brought more shower chances
in by late next Friday.

&&

.AVIATION /Discussion for 070600Z TAF Issuance/...
Issued at 1140 PM EDT Sat Oct 6 2018

Restrictions expected...especially at KLAF late tonight and Sunday
morning...and in and around convection. VFR conditions otherwise.

The frontal boundary continues to press south towards the Interstate
70 corridor late this evening. VLIFR ceilings have developed north
of the front at KLAF and may briefly impact KHUF and KIND with
variable wind direction if the front can get near or even pass both
sites before the front pulls back north during the predawn hours.
Any convection should remain scattered with KLAF likely being the
only terminal with a potential impact.

The frontal boundary will lift back north early Sunday and set up
once again across north central Illinois and Indiana during the day
with any convective development focused in the vicinity of the
boundary. Again...KLAF would be the most likely of the terminals to
be impacted by any storms Sunday afternoon...but plan on leaving any
precip mention out at this time with low confidence. Dry conditions
with scattered clouds are expected further south at KBMG...KHUF and
KIND Sunday.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...TDUD
NEAR TERM...Ryan
SHORT TERM...TDUD
LONG TERM....MK
AVIATION...Ryan



Area Forecast Discussion

National Weather Service North Platte NE

 646 PM CDT Sat Oct 6 2018

.SHORT TERM...(This evening through Sunday)
Issued at 308 PM CDT Sat Oct 6 2018

The HREF, RAP and HRRR models suggest the rain developing across the
cntl Rockies will move north tonight and a portion of it could reach
northwest Nebraska. The HRRR, RAP and NAMnest all indicate rain (not
a mix of rain and snow) which is consistent with temperatures above
0C at h850-700mb.

The main area of rain for Sunday should develop across KS tonight
and lift into swrn Nebraska by morning. This rain is operating on
deepening moisture and isentropic lift but the NAM and GFS model
soundings indicate a sliver of elevated CAPE and unidirectional winds
aloft which should support multicell showers and isolated
thunderstorms.

The temperature forecast tonight leans on the deterministic model
blend plus bias correction for lows in the 30s. This is warmer than
the guidance blend. Meanwhile, forecast highs in the 40s Sunday are
based on the same deterministic model blend plus bias correction
which was cooler than the guidance blend.

.LONG TERM...(Sunday night through Saturday)
Issued at 308 PM CDT Sat Oct 6 2018

The base of a long wave trough over the Great Basin is forecast
to move over the Four Corners Region Sunday night. Meanwhile, a
strong upper ridge over the Mid Atlantic and Southeastern U.S.
will help maintain a south southwesterly flow aloft to the area
with deep moisture available. Rain chances increase to 80 percent
Sunday night into Monday morning, then likely POPs in the
afternoon. A mix of rain or snow is possible late Sunday night
across the Pine Ridge in northern Sheridan County. There is also
a chance for isolated thunderstorms Sunday night into Monday due
to weak instability and unidirectional winds.

The base of the upper trough in the West will lift into the
Central and Northern Plains Monday night through Tuesday night.
POPs to range from 50 to 70 percent Monday night into Tuesday
morning, increasing to 70 to 80 percent Tuesday afternoon into
Tuesday night. There will be a chance for light snow or a
rain/snow mix across the western Sandhills later Monday night into
Tuesday morning. Temperature profiles look marginal for little
accumulation expected. Sufficiently cold sounding profiles on the
backside of the system would indicate better chances for light
snow accumulations Tuesday night. Due to differing model
forecasts, confidence is low at this time on any accumulations.

Highs on Monday forecast to range from the low to mid 40s
northwest, and the lower 50s southeast. However, the GFS maintains
warm air advection and much milder highs possible. Then for
Tuesday through Thursday, highs should range mostly in the 40s,
then reaching the lower 50s by next Saturday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 646 PM CDT Sat Oct 6 2018

MVFR to IFR ceilings are expected to develop across southwest
Nebraska between 06-12z Sunday morning and spread northward
through the day. Rain is expected which will lower visibility.
There`s moderate confidence on timing of the precipitation and
when ceilings change flight categories, but overall confidence is
good.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...CDC
LONG TERM...Roberg
AVIATION...Jacobs



Area Forecast Discussion

National Weather Service Chicago/Romeoville, IL

 811 PM CDT Sat Oct 6 2018

.UPDATE...
811 PM CDT

Evening Update...

Significantly lowered pops across the area this evening,
especially farther north. Precip chances gradually increase again
after midnight, and added some chance thunder mention, especially
south, during the overnight/pre-dawn period.

Surface cold front continues to push slowly southward across
central IL and IN this evening, with cool north low level flow and
weak subsidence in the wake of a departing short wave helping to
greatly limit precip across the cwa. While a few spotty showers,
or perhaps some drizzle is possible south of the I-80 corridor
this evening, most areas will remain dry. Of course, the elevated
frontal zone remains aloft across the region, and modest 15-20 kt
southwesterly flow around the 850 mb level will maintain weak but
persistent warm/moist advection aloft. Another low-amplitude short
wave is evident lifting out of eastern KS/MO per GOES-16 vapor
imagery, and this feature should provide some enhancement to moist
ascent across the area later tonight. Various model runs indicate
development of scattered showers and perhaps a few thunderstorms
back into the area mainly after midnight, so have ramped back up
to likely pops overnight. SPC RAP mesoanalysis depicts elevated
MUCAPE axis primarily over the southeastern part of the cwa this
evening, though aforementioned warm/moist advection is expected to
bring some weak elevated instability farther north later tonight.
Both forcing and instability is significantly weaker than last
night however. Shower coverage looks to decrease after sunrise,
though spotty light rain or drizzle will likely persist as modest
warm/moist advection flow continues aloft.

Updated digital grids and text forecasts available.

Ratzer

&&

.SHORT TERM...
302 PM CDT

Tonight and Sunday...

Periods of active weather are expected through mid-week as the upper
level pattern continues to amplify the longwave pattern with a
building upper ridge over the ern CONUS and a deepening trough over
the wrn CONUS.  The central CONUS, including the local area will be
under fast flow aloft, with strengthening upper level flow which
will gradually back from wswly to sswly through mid-week.  The
weather across the local area will remain active while the region is
under this fast swly flow aloft.  By late in the week, the longer
range guidance is indicating that the pattern will become more
progressive, with the upper level trough axis finally shifting east
and setting up a more moderate period of dry weather.

For tonight, a cold front will continue to sag southeast, with the
active convection pushing southeast of the CWA by early evening.
Behind the sfc front, mid-level swly flow will continue to stream
deep layer moisture across the region, with the continued potential
for showers and dense cloud cover through the overnight hours and
into early tomorrow morning.  The potential for thunderstorms will
mainly be along or slightly behind the sfc front, where broad scale
isentropic lift will coincide with weak elevated instability. By
Sunday morning, the front is expected to stall over cntrl IL/IN. Any
sfc based instability will be south of the front, with only the far
southern portions of the CWA keeping enough instability to maintain
a thunder potential.  So, have scaled back the thunder potential for
late tonight and tomorrow as cool nely flow and cloudy skies will
set up across locations generally north of the Illinois and Kankakee
River Valleys, including the Chicago and Rockford Metro areas. The
latest guidance suggests that any residual instability will likely
be south of the sfc front through the day, where there. may still be
a chance for some more thunderstorms.  North of the boundary,
thunder potential will diminish rapidly, with pcpn mainly light rain
or sprinkles.   Temperatures across the CWA will vary significantly,
with locations south of the front in the lowers 70s to around 80 F.
North of the front, under cloudy skies and cool nely winds, max
temperatures should range from the lower 60s over the Chicago Metro
area to the upper 50s over the Rockford Metro area.

&&

.LONG TERM...
302 PM CDT

Sunday Night through Saturday...

The front is expected to surge back north again Sunday night as a
new low develops over the western plains.  This will put the CWA
back under warm, moist southerly flow with another air mass change
back to warm sector air, with temperatures on Monday climbing back
into the 80s, with locations south of I-80 possibly reaching the
middle 80s.  Dewpoints will also climb back into the middle 60s as
well.  The return of the warm, moist air will set up the potential
for another round of showers and thunderstorms.  Some of the longer
range guidance is suggesting that a tropical system may develop over
the Gulf of Mexico, which will help build sfc ridging from the Mid-
Atlantic region through the lower Mississippi Valley.  This could
temporarily cut off the direct flow of Gulf moisture, and lead to a
short lull in pcpn potential.  By Tuesday night or Wednesday, this
tropical system may make landfall somewhere over the ern Gulf Coast,
and break down the sfc ridging and help set up a renewed return flow
of warm, moist air in advance of a cold front pushing across the
plains.  While this tropical system is NOT expected to have any
significant impact on the local area, the moisture pooling along the
cold front will bring the next significant chance for heavy rainfall
and thunderstorms to the local area for Wednesday into Wednesday
night.  Confidence in timing of this frontal passage will be the
main concern with the longer range guidance showing a bit of a
spread in the eastward speed of the system.  Temperatures should
remain well above normal at least through Tuesday with highs in the
lower to middle 80s.  Temperatures Wednesday will be a little more
uncertain, depending on the timing of the frontal passage.  Following
the passage of this front, temperatures should trend back closer to
seasonal normal levels with highs in the middle 50s to lower 60s
from Thursday and into next weekend.  Conditions should be dry
following the frontal passage as high pressure builds across the
region.

&&

.AVIATION...
For the 00Z TAFs...

636 pm...Forecast concerns include cigs through the period and
scattered showers overnight into Sunday morning.

Cigs across much of northern IL are slowly lifting through low
mvfr with cigs above 2kft across parts of southeast WI. Cigs may
continue to slowly lift to 2kft or higher this evening. However...
by early Sunday morning cigs are expected to drop back into ifr
as scattered showers develop across the area. Timing of these
showers as well as location remains somewhat uncertain. It had
appeared these may stay south of the terminals but latest trends
suggest showers across much of the area. Instability looks rather
low so not expecting much thunder but trends will need to be
monitored overnight. As this area of precip ends in the morning...
there may still be light showers or some drizzle through midday.
Beyond that time period...there appears to be a lull in precip
chances with perhaps another chance of showers later Sunday
evening into early Monday morning. Cigs will likely lower Sunday
morning into lifr especially if drizzle materializes with only
slow improvement to ifr Sunday afternoon. Guidance is in fair
agreement with cigs lowering again with sunset Sunday evening.
Patchy fog will be possible with perhaps the best time for more
widespread fog Sunday evening as cigs lower. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...nearshore waters
     until 4 AM Sunday.

&&

$$

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Area Forecast Discussion

National Weather Service Twin Cities/Chanhassen MN

 1048 PM CDT Sat Oct 6 2018

.UPDATE...
Issued at 1024 PM CDT Sat Oct 6 2018

Updated to include 06z aviation discussion below.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 406 PM CDT Sat Oct 6 2018

It`s another cloudy day today, with high pressure coming in from
Canada supplying us with cool and dry air as well. Visible
satellite imagery does show this stratus deck becoming a bit
cellular, so we will see a few peeks of sunshine this afternoon,
but expect a cloudy period on the whole, with NAM forecast
soundings showing the layer between 2000 and 3500 feet remaining
pretty much saturated. Whatever clearing we see this afternoon
will fill back in tonight as moisture and WAA advection commence
in the 925-850mb layer in response to the deep trough currently
over the Rockies starting to come out on to the high Plains. The
cloud cover will keep temperatures from really cratering tonight,
but as we see with temperatures this afternoon, the air with this
high is quite cool on its own, so lows in the mid 30s to lower 40s
should be easy to achieve. This favors the warmer end of guidance
for lows tonight and if we end up with a few hours of less cloudy
skies to start the night, we could certainly see low lower than
what we currently have.

On the whole, Sunday looks cloudy once again, with rain starting
to move into southern MN late in the afternoon. The cold front
that this afternoon that stretches from OKC northeast to along the
I-94 corridor in Michigan will basically stall in its current
location through the night and begin heading north as deep
southwesterly flow develops aloft and height falls start moving
out on to the Plains. It will take some time for rainfall to the
north of the front to get here, but as a southerly h85 jet
strengthens into IA during the afternoon, we`ll see isentropic
lift quickly build into southern MN. Still some timing differences
with how quickly rain comes north Sunday afternoon, with the GFS
continuing to be on the slow side of guidance. Looks like
saturation and rainfall move in fast during the afternoon and for
now went with a timing that`s a blend of the fast RAP and the
slower GFS. No matter what happens with the rain, this will merely
be the start of a significant and prolonged rainfall event, with
better moisture transport and threat for heavier precipitation
arriving Sunday night.

.LONG TERM...(Sunday night through Saturday)
Issued at 406 PM CDT Sat Oct 6 2018

Despite a pretty remarkable and anomalous weather event next
week, the set up is rather simple lending to high confidence. A
highly anomalous ridge off the mid Atlantic coast and an equally
impressive anomalous trough over the southwestern U.S. will set up
meridional flow from the western Gulf of Mexico to the Upper
Midwest. A very moist airmass and a stationary front stretching
from the eastern Plains to southeastern MN and central WI will
focus an area of continuous rainfall across much of the CWA from
Sunday night until the main wave finally passes through Wednesday.
Helping sustain this area of rain will be a 35-45 kt LLJ
paralleling the stationary front, pwats climbing to 1.5 to 1.75
inches Monday and Tuesday (3-4 standard deviations above normal
and near record values), and several waves rippling along the
front. Continued the categorical 80-100 PoPs Sunday night into
early Wednesday. The given blended QPF seemed too low, so Upper
Midwest WFOs loaded in straight WPC QPF through the event. The
thunder threat looks low given poor lapse rates, but given the
proximity of the surface front, maintained low chances across the
south and east.

The main question is where the heaviest axis will set up. GFS is a
bit further north than the rest of the guidance and ensembles. EPS
shows a wide swath of very high probabilities for greater than 2
inches of storm total rainfall across southern/eastern MN into
northern and central WI. There are even 20-30 percent probs of
greater than 5 inches in this corridor, which seems reasonable.
Issued a Special Weather Statement to highlight the heavy rain and
flood threat, but Flood Watches will eventually be needed.

After consulting with the NCRFC, 5 day WPC QPF would result in at
least minor flooding on the Minnesota, Mississippi, and their more
flood prone tributaries. More significant flooding looks to
remain south of the region.

A much more tranquil pattern will resume for late week, although
it does look even colder. A couple clipper systems could bring low
chances for rain or snow to much of the region Friday or Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1024 PM CDT Sat Oct 6 2018

MVFR ceilings to persist throughout this TAF set as winds become
northeast for the duration. High pressure to the north sliding to
the east of the area will help keep the NE winds going and keep
precipitation away from the area through the daytime hours
tomorrow but this is aid in keeping the lower ceiling in place.
The influence of high pressure will wane going into tomorrow
evening, in conjunction with a warm front to the south lifting
north. Rain will then move in from the south around 00z Sunday
evening and steadily spread north and east Sunday night into
Monday. After the precipitation starts, and mainly around daybreak
Monday morning, chances for IFR ceilings increase significantly.

KMSP...MVFR ceilings expected throughout this set, bouncing
between 1500-2500 ft, with IFR ceilings likely around daybreak
Monday morning. NE winds throughout with winds 5-10kt. Sustained
rain looks to move into the area around 00z Sunday evening. May
be some more isolated/broken showers before that but best timing
of persistent rain to start late afternoon into early evening then
continue through the night. Visibilities likely to drop as the
rainfall continues.

/OUTLOOK FOR KMSP/
Mon...MVFR/IFR with -RA chc TSRA. Wind SE 5-10 kts.
Tue...IFR/LIFR with -RA. Wind S bcmg NW 10 kts.
Wed...MVFR chc IFR cigs. Wind NW 10-15 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

UPDATE...JPC
SHORT TERM...MPG
LONG TERM...BORGHOFF
AVIATION...JPC




Area Forecast Discussion

National Weather Service Pueblo CO

 346 PM MDT Sat Oct 6 2018

.SHORT TERM...(This evening through Sunday)
Issued at 311 PM MDT Sat Oct 6 2018

Current water vapor imagery and upper air analysis is indicating
moderate to strong southwest flow aloft across the state, with a
broad upper trough digging into the Great Basin. Water vapor imagery
is also indicating one embedded short wave rounding the base of the
trough across north central Arizona, as more energy continues to dig
down the backside of the system across the West Coast. Regional
radars are currently indicating scattered showers, along with a few
embedded thunderstorms, lifting out across eastern Utah and
northwest Colorado at this time. At the surface, moist east to
southeast upslope flow across the eastern Plains has kept clouds in
place across the Pikes Peak region and the far southeast Plains
through out the day, with current temperatures in the upper 40s to
upper 50s across the eastern Plains, and mainly in the 30s and 40s
across the higher terrain, save for 60s in the San Luis Valley, with
breezy southerly winds at this time.

No big changes to current forecast with lastest models in decent
agreement through the day Sunday developing deep southerly flow
aloft as the West Coast energy continues to dig the trough into the
the Desert SW. Models agree that the embedded short wave will lift
into the Four Corners region this evening and continue across
Western Colorado through the day tomorrow. Progged movement of the
system will keep best coverage of showers and storms across the
Central Mountains through the evening, with focus of precipitation
shifting to the Southwest Mountains overnight, which then continues
through the day Sunday. Southerly flow aloft to keep snow levels
relatively high through the day tomorrow, with 1 to 5 inches of
accumulations possible generally above 10K ft with the greatest
amounts expected across the higher elevations of the San Juan and La
Garita Mts. Further east, moist upslope flow persists with stratus
expected to fill back in across the Southeast Plains through the
evening. With WWA aloft, can`t rule out a showers and a few
thunderstorms developing overnight, especially across extreme
southern Colorado, from the Raton Mesa through the far southeast
Plains, where the latest HRRR is indicating elevated convection
early Sunday morning. Deep southerly flow aloft will allow for
breezy to windy conditions to develop over and near the higher
terrain. Overnight lows are expected to be in 30s and 40s area wide,
with highs tomorrow remaining below seasonal levels, mainly in the
50s across the lower elevations, and 30s and 40s across the higher
terrain. Could again see highs touching the 60s across the San Luis
Valley and portions of the Southern I-25 Corridor, with southerly
downslope flow.

.LONG TERM...(Sunday night through Saturday)
Issued at 311 PM MDT Sat Oct 6 2018

...First moderate snow event of the season possible for the
mountains...

Models are in fairly good consensus with the large scale details
associated with developing long wave trof/upper low across UT/AZ
through Sunday, which is progged to lift out across the 4 corners
region/NW NM Monday night and across CO on Tuesday. Timing and
location of the front across the plains is still in question as it
retreats northward Sunday night and surges back southward on
Monday in response to falling surface pressures to the south. GFS
is still the outlier with the farther north surface front position
on Monday and have continued to leaned towards the faster, farther
south frontal position advertised by the NAM and ECMWF.

For sensible weather during this period, snow levels will fall
across the southwest mountains Sunday evening with potential for
embedded thunderstorms as the first round of of lift associated
with ejecting energy from the upper trof, along with instability,
affect the region. Could see some intense snowfall rates with
embedded convective showers and this explains the differences in
the GFS/NAM concerning QPF across the southwest mountains with
NAM12 rather heavy handed. Across the southeast mountains and
plains, ejecting wave will kick off a round of thunderstorms
around 00z, which will race off to the northeast. For now, it
appears thunderstorms will be more elevated, and CAPE limited,
which should keep thunderstorms sub severe across the plains in
spite of rather favorable shear. Still could be a strong storm or
two with small hail and strong winds possible during the evening.

Dry slot spreads up from the south on Monday which will decrease
snowfall across the southwest mountains for much of the day.
Meanwhile, pressure falls to the south should cause the front to
advance southward through the plains again, with warmest readings in
the morning to early afternoon the farther north you go, before
temperatures start dropping again in the mid-late afternoon.
Potential for severe thunderstorms looks low for southeast Colorado
now with best instability now shifted farther to the east and south.
Will still have to watch the surface feature placement as the risk
for severe thunderstorms will be close to the southeast corner of
the state.  Precipitation fills in again Monday night and Tuesday as
the upper trof ejects to the northeast across southeast CO.

Overall, Continental Divide should fair well with snowfall from this
event...though given the high snow levels in the initial stage of
the storm, along with dry slot for Monday and open nature to the
storm system for Monday night/Tuesday, snowfall amounts and
especially impacts may come in more in the advisory range.  Snow
levels will drop down to around 7000 feet Monday night and Tuesday
and there could be some snow mix in for the Palmer Divide and
portions of El Paso county Tuesday morning. Overall, it does not
look like a heavy event for the southeast mountains either as system
opens up and H7 flow never really attains a strong northeast upslope
component. Northerly flow off the Palmer Divide may even shadow
Pueblo area given downslope.

System pulls off to the northeast for Tuesday night with a lull in
the activity for Wednesday. Will have to watch Tuesday for a
potential frost or freeze highlight if clouds can clear out fast
enough across the plains.  The next system will be dropping in from
the NW on Thursday which ramps up precipitation chances for the
mountains again.  Front drops through the southeast plains which may
bring another uptick in precipitation chances through Friday
morning. This northern stream system is now driving the remnants of
Sergio farther south across NM...so this may be less of a player
than earlier thought.  But there are bound to be more changes in the
evolution of the pattern as time goes on, so stay tuned.  -KT

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 311 PM MDT Sat Oct 6 2018

A broad upper trough will continue to dig into the Great Basin
region with deep southerly flow aloft developing across the state
through this taf period. This will keep moist upslope flow in place
across the Southeast Plains through the period. With that said, VFR
cigs expected at COS and PUB through the early evening, with cigs
lowering to between bkn015-030 through the overnight hours. Could
see patchy fog develop at COS as well, though not enough confidence
to include in the taf at this time. There will be increasing
coverage of showers and thunderstorms across the area tomorrow
afternoon, especially in Pikes Peak region.

VFR conditions expected at ALS through the taf period. Breezy
southerly winds to develop this afternoon and diminish this evening
before picking up again through Sunday morning.

&&

.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...MW
LONG TERM...KT
AVIATION...MW