Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/17/19

Area Forecast Discussion

National Weather Service Green Bay WI

 608 PM CST Sat Nov 16 2019

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Sunday
Issued at 239 PM CST Sat Nov 16 2019

The latest RAP analysis and satellite/radar imagery show high
pressure exiting over the eastern Great Lakes while low pressure
is moving east over southern Manitoba. Mid-level clouds continue
to move east across the region above scattered to broken mvfr
strato-cu. Think some of these low clouds will erode through the
rest of the afternoon. Precip is developing over South Dakota and
falling out of a mid-level cloud deck. As this storm system moves
east, timing and accumulations of wintry precip are the main
forecast concerns.

Tonight...Low pressure and associated frontal system will continue
to track east into Wisconsin late. Timing has slowed a bit, and
the cold front may not move into northwest Wisconsin until closer
to 12z Sunday. Timing of precip has slowed as a result, arriving
into north-central WI in the 4 to 6 am time period. Could see up
to a half inch of snow accumulations by 6 am over western Vilas
county. Otherwise, will see clouds gradually thicken and lower
through the night. With a mild south wind and cloud cover, temps
should only fall into the middle to upper 20s.

Sunday...Precipitation will continue to move east along the cold
front, but gradually diminish in the process. Temps should be cold
enough for precip to fall mainly as snow over central and north-
central WI. This should result in an additional accumulations of
up to an inch. By the time precip moves into northeast WI,
including the Fox Valley, temps are forecast to warm into the
middle 30s, making precip more of a rain/snow mix. With precip
forecast to thin out, accumulations continue to look minor in
this area, and perhaps a couple tenths are possible. Forecast
soundings indicate that mid-level moisture departs during the
afternoon on the trailing edge of the precipitation band. Could
therefore see precip mix with or change over to freezing drizzle
for a time, mainly over north-central WI where temps will be near
freezing. But don`t think any freezing drizzle will lead to much
impacts with temps near freezing and time of day considerations.

.LONG TERM...Sunday Night Through Saturday
Issued at 239 PM CST Sat Nov 16 2019

An upper level trough and associated cold front will be moving
through the forecast area Sunday evening, so will keep a chance of
precipitation in the east and north part of the cwa. Moisture will
be shallowing out, so any lingering light snow may change to
drizzle or freezing drizzle. Temperatures in eastern WI may also
be warm enough for a mix of light rain/snow early.

Generally dry conditions are anticipated as a ridge of high
pressure moves through WI Monday and early Monday night. A warm
front will impact the forecast area late Monday night into
Tuesday, but will not have much moisture to work with. For now,
will only carry low-end pops for light snow or freezing drizzle.

A potentially stronger system is expected to arrive Wednesday
night into Thursday, but there are strength and timing issues
with the medium-range models. The GFS is strongest and farthest
north with the surface low, and brings a significant rain to much
of the cwa, while the ECMWF is farther south, colder and not as
strong. Have bumped up pops to likely in the southeast part of the
forecast late Wednesday night into Thursday morning. Later
forecasts will be able to provide more details on the likely track
and strength of the low in upcoming days, with better estimates
on QPF, as well as potential snow accumulations on the colder
northwest periphery of the storm.

As this system exits, there will be potential for a brief period
of light lake effect snow showers over north central WI Thursday
night.

Models diverge for the weekend, with the GFS suggesting a
generally dry forecast, while the ECMWF supports a chance of
snow showers as an upper trough swings through the region.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 608 PM CST Sat Nov 16 2019

Some MVFR clouds persisted across portions of eastern WI late
this afternoon, with mid-upper clouds across the rest of the area.
Look for the MVFR clouds to continue to dissipate/exit eastern WI
as winds become southerly, lingering the longest at KMTW.

Flying conditions will deteriorate on Sunday as snow spreads west
to east across the area. IFR CIGS and VSBYs are expected for a
few hours in the heaviest precip. A period of LIFR conditions are
possible as well, mainly at KAUW, KCWA, and KRHI Sunday morning.
As temps climb through the day, look for the snow to mix with or
change to a period of rain, especially across central and eastern
WI. As the steady precip exits in the afternoon, a period of
drizzle and freezing drizzle is expected. Only minor improvements
in CIGS are expected in the afternoon.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......Bersch



Area Forecast Discussion

National Weather Service Wilmington NC

 653 PM EST Sat Nov 16 2019

.SYNOPSIS...
Periods of rain, very strong wind, and unseasonably cool
temperatures will prevail through the remainder of the weekend,
as powerful low pressure deepens off the Carolina coast. The
storm will move away from the area late Sunday, with rain and
wind trending down. High pressure will follow early next week,
with drier and warmer weather into mid week. A cold front is
expected to move through the area late next week.

&&

.UPDATE...
WINDS: Almost all synoptic/mesoscale models show the strongest
975 mb winds (45-50 kt) affecting the coast between now and
06z. The Frying Pan Shoals buoy has gusted to 58 kt/67 mph
within the past hour. Gusts on the beaches have reached 59 mph
at Wrightsville Beach, and 45 mph on Topsail Island. Weatherflow
station peak gusts include 51 mph at Federal Point, NC; 49 mph
at Oak Island, NC; and 48 mph at Lake Arrowhead near Myrtle
Beach, SC. At the Wilmington airport gusts have reached 47 mph,
with 46 mph at North Myrtle Beach. The Wind Advisory was earlier
expanded one tier of zones westward, and continues into Sunday.

TEMPS: Temps may rise a bit along the NC coast overnight, with
steady to slowly falling temps anticipated across most of
northeastern South Carolina. Forecast lows are raised to around
40 on the I-95 corridor, mid 40s SC beaches, and upper 40s NC
beaches. Used a raw model-based curve (non-diurnal) to calculate
hourly temps through Sunday morning.

POPS/WX: Used 18z NAM and 22z HRRR to nudge PoPs/Wx grids
overnight. Inland rain should largely dry up around midnight,
but waves of rain and some evening elevated convection will
continue overnight nearer to the coast. Overall reduced QPF
forecasts, especially inland.

COASTAL FLOODING: Expanded the coastal flood advisory to cover
the Brunswick County coast. Despite offshore winds, the offshore
storm has pushed water levels high enough along the entire
Carolina coastline to produce flooding during Sunday morning`s
high tide. This is one to watch: the latest ETSURGE guidance has
Wrightsville Beach getting within about 3 inches of moderate
(warning-level) coastal flooding Sunday.

&&

.NEAR TERM /THROUGH SUNDAY/...
High Surf Advisory for Pender, New Hanover beaches ongoing through
much of Sunday, as 8-13 foot breakers crash onshore. This threat
will escalate with Sunday morning`s high tide, as coastal flooding
and high water run-up reach peak, increasing the danger for
beachgoers, especially anyone entering the surf, or venturing too
close to the surf`s edge without a flotation device.

Strong winds caught in the pressure grip of the potent coastal low
will peak this evening, holding strong overnight, with more notable
abating of wind Sunday afternoon. As a result the `Wind Advisory`
for the NC coast will remain intact, with N gusts as high as 45-50
mph from Surf City to Wrightsville Beach to Carolina Beach to Fort
Fisher to Bald Head Island, to eastern Brunswick county coast
tonight and early Sunday. Weakened trees or large branches from
Hurricane Dorian`s impacts could topple as winds peak late today,
overnight, and early Sunday morning.

Approximate center-line of QPf ensembles, pointing to an additional
1.5-2 inches along the NC coast, 3/4-1.25 inches along the NE SC
coastal zones, and 1/3-1 inch for most of inland SE NC and NE SC.
Areas west of I-95 may only see additional amounts around 1/4 inch.
Do not anticipate big flooding problems, but isolated training of
rain, or brief high rain-rates, could cause localized flooding, and
dangerous water ponding on highways.

Wind, clouds, rain, and a singular air mass, will keep temperatures
at and by the coast, nearly flat-lined, whereas diurnal temperature
ranges well inland will show greater spreads between
max-T/min-T.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
A mid level trough will move across the area through the day
Monday and guidance, although seemingly going back and forth is
once again developing some light showers across the area. Have
added little activity (pop) with this development and to align
with adjacent offices as well. Highs Monday will be in the
middle to upper 50s and lows Tuesday morning with some clearing
will be a couple of degrees either side of 40.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
The extended period remains relatively unchanged with the mid
level trough moving across early in the week transitioning to a
somewhat progressive mid level ridge. A broad split flow wants
to develop late although there are timing differences with the
guidance. A cold front, mainly associated with the northern
branch moves across very late in the period. Not necessarily a
significant system but low pops are warranted. No significant
changes to the temperature forecast which offers little
deviation from climatology until late when warmer readings
develop.

&&

.AVIATION /0Z SUNDAY THROUGH THURSDAY/...
Predominantly MVFR this TAF period, with chance for IFR ceilings
overnight into tomorrow morning. As strong nor`easter offshore
slowly moves northeastward, abundant low level moisture and tight
pressure gradient will keep ceilings mainly around 1500 ft across
the area with strong northerly winds. Light rain will slowly
taper off across NE SC, and linger in coastal NC areas through
tomorrow afternoon. Included IFR ceilings at ILM overnight where
confidence is higher, but IFR possible elsewhere as well.

Strongest winds will be between now and 12z, sustained between
15 and 20 kts inland and 20-25 kts along the coast, with gusts
mainly between 25 and 30 kts. Gusts up to 40 kts at times possible
at coastal sites overnight. Have included low-level wind shear
at ILM due to forecasted winds at 2 kft over 50 kts overnight.
Wind shear at MYR and CRE will be close to criteria with 2 kft
winds near 50 kts.

Extended Outlook...Sub-VFR ceilings could linger Sunday into
Monday afternoon, mainly along the coast and SE NC. Becoming
VFR Monday through Thursday, with chance for fog Tuesday morning.
&&

.MARINE...
Dangerous marine conditions, venturing out and especially offshore
is highly discouraged. Storm Force winds will rip across the NC
waters and buoy 41013 has already reported gusts to 51 knots, or
about 59 mph. Gale force winds will rake the SC waters, with a few
storm force gusts possible beyond 15 nm tonight and early Sunday.
Noticeable lessening of winds will be seen by Sunday afternoon, but
still dangerous as large seas propagate through the waters. Seas
made up of NE waves 9-14 every 10-12 seconds, with lashing N chop in
the mix on top of these large waves. If all this were not convincing
enough to stay in port, isolated TSTMs are possible offshore, mainly
beyond 10 NM through this evening.


No real significant systems to drive winds and seas too high
for basically the short and long term period. More variability
in the winds, which is typical if anything. A decent northwest
flow of 10-15 knots will be in place initially associated with
the waning impacts from this weekend`s coastal storm. Weak high
pressure will dominate the mid week period with a weak boundary
moving across later Tuesday to kick up the winds briefly. A
decent and prolonged (at least for the winter season) return
flow develops late and increases gradually in magnitude. Could
see some 15-20 knot speeds here. Significant seas basically
follow the winds with 2-4 feet with maybe an increase late with
the better fetch.

&&

.TIDES/COASTAL FLOODING...
Dangerous beach conditions through Sunday morning. Tidal flooding
will combine with large storm-waves, to bring significant coastal
flooding and sea-water run-up at areas beaches. The offshore wind at
Brunswick county will help stem the reach and advance of water
there, and to a lesser extent at east facing beaches.

Erosion will occur Sunday morning, as water levels approach the more
rare `moderate` flooding threshold, possibly breaching low dune
spots, with exception of Brunswick county. Right now, predicted
water levels to make the upper reaches of `minor` category, but this
could change to moderate with any increases in predicted levels.

The lower Cape Fear river also to experience significant water rises
Sunday morning, especially with all the rain run-off, and river
levels also approach moderate stages, resulting in much more
extensive impacts to residents affected by high water levels on the
lower Cape Fear river, and adjacent roadways.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Wind Advisory until noon EST Sunday for SCZ054.
     Coastal Flood Advisory until 2 PM EST Sunday for SCZ054-056.
NC...Wind Advisory until noon EST Sunday for NCZ105>110.
     High Surf Advisory until 6 PM EST Sunday for NCZ106-108.
     Coastal Flood Advisory until 2 PM EST Sunday for NCZ106-108-
     110.
     Coastal Flood Advisory from 10 AM to 2 PM EST Sunday for
     NCZ107.
MARINE...Gale Warning until noon EST Sunday for AMZ254-256.
     Storm Warning until 6 AM EST Sunday for AMZ250-252.

&&

$$

SYNOPSIS...SHK
UPDATE...TRA
NEAR TERM...MJC
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...VAO
MARINE...MJC/SHK
TIDES/COASTAL FLOODING...




Area Forecast Discussion

National Weather Service Louisville KY

 1003 PM EST Sat Nov 16 2019

.Forecast Update...
Issued at 1002 PM EST Sat Nov 16 2019

A quiet night is in store. Skies will be mostly clear, other than
some scattered cirrus high overhead. Atmospheric cross-sections
show very light winds by dawn from the surface to about 800mb, and
temperatures will fall toward crossover temperatures. However, today
was the fourth dry day in a row and most guidance keeps surface dew
point depressions of a few degrees at dawn, so will continue with
forecast of patchy fog...with the best fog chances in the usual
river valleys...which generally agrees with RAP and NARRE progs.

&&

.Short Term...(This evening through Sunday)
Updated at 315 PM EST Sat Nov 16 2019

Surface high pressure beneath flat upper level ridging over the
region continues to provide sunny skies and dry conditions across
the Ohio Valley. Current satellite shows some mid and high clouds
streaming across IL, which should provide a beautiful sunset for
many this evening. Clearing skies overnight may result in some
patchy fog early Sunday morning, mainly north of the parkways and
within river valleys. Sunday will start off cold with temps in the
mid 20s. Expect to see increased mid and high level clouds
throughout the day Sunday ahead of a cold front that will be
positioned N-S along the Mississippi Valley. Clouds will do little
toward impeding diurnal warming; therefore, expect to see max temps
reach into the upper 40s to low 50s.

.Long Term...(Sunday night through Saturday)
Updated at 340 PM EST Sat Nov 16 2019

Sunday Night through Tuesday Night...

Upper level pattern looks to remain in a ridge west, trough east
type pattern through this period.  Our region will sit within a mean
trough axis with several weaker perturbations moving through the
region.  Model proximity soundings are still rather meager with the
overall moisture over our region.  However, there may be just enough
forcing to get some light precipitation at times.  The first
perturbation will move through the region late Sunday night and
early Monday.  With the system moving through overnight, model
soundings suggest that we could have a mix across southern Indiana
where near term surface temps very close to freezing.  Highs on
Monday look to rebound thorugh into the upper 40s to around 50.

Another weak system looks to move through late Monday night and
early Tuesday.  Again model soundings are suggestive that some mixed
precip could occur.  However, morning lows Tuesday morning look to
be slightly warmer than Monday morning.  Overall forcing with this
system looks a little weaker, so precipitation would be rather light
and very scattered.  Highs again will rebound into the upper 40s and
lower 50s. Lows Tuesday night will drop back into the 33-35 degree
range.

Wednesday through Saturday...

Global models are in good agreement with a period of ridging for
Wednesday.  Given the good model agreement and rather consistent
signaling here, yields a higher confidence forecast of dry and
pleasant conditions for Wednesday.  Afternoon highs look to top out
in the low-mid 50s over southern Indiana and far northern Kentucky.
Highs across the southern half of the state look to warm into the
upper 50s to around 60.  Wednesday night lows look to cool back into
the upper 30s to the lower 40s.

For the Thursday through Saturday period, forecast confidence drops
to below normal for a few reasons.  First, we will have a split flow
pattern setting up across the CONUS.  Dynamical models struggle
highly in a split flow regime.  Secondly, we will have to watch two
features within the pattern that could potentially impact us for the
late week period.  First feature is a fairly potent mid-level trough
within the northern stream and the second feature is a cut off low
over the southwest US.  Earlier in the week, the global models were
suggesting that these two features would eject out similarly and
phase as they headed across the country.  Yesterday, there was ample
agreement that the northern stream system would dive down and dig
faster leaving the southern stream system behind.  Today`s Euro and
CMC models continue this line of thinking keeping the systems
unphased with ample ensemble agreement as well.  Today`s GFS/FV3
solution attempts to phase the streams, but have given more weight to
the Euro/CMC OP/Ens solutions here.

With that thinking, we`ll swath of widespread rain showers move into
the region late Wednesday and continue through the day on Thursday.
Some colder air may get in on the back side of that system by Friday
morning allowing for a possibility of a change over to snow before
ending.  As always, it will be a race to see if the cold air can
catch the back side of the precipitation shield.

Today`s data suggest that a secondary northern stream wave is
forecast to dip out of Canada and into the Plains.  This secondary
wave may end up phasing with the slower southern stream system
bringing another storm system through the region on Saturday.
Depending on the evolution of the upper level features, the track of
this system is highly uncertain and will likely change a bit over
the next week.

&&

.Aviation...(00Z TAF Issuance)
Issued at 627 PM EST Sat Nov 16 2019

Overall, aviation concerns should be minimal over the next 24-30
hours. Some light fog could lower conditions to MVFR, especially
between 11-14z, at HNB/SDF/LEX. Otherwise, VFR conditions likely.
Mainly clear skies overnight with just brief SCT cirrus. Northeast
winds around 5 kts are forecast to diminish to nearly calm by 09-12z
Sun.

Winds will remain light throughout Sunday with a baggy gradient in
between weather systems. We`ll see a substantial increase in high
level cloud cover during the afternoon and evening hours.


&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...13
Short Term...CG
Long Term...MJ
Aviation...EBW



Area Forecast Discussion

National Weather Service Marquette MI

 527 PM EST Sat Nov 16 2019

.SHORT TERM...(This evening through Sunday)
Issued at 418 PM EST SAT NOV 16 2019

WV imagery and RAP analysis indicated an upstream mid/upper level
trough from Manitoba into western North Dakota and eastern WY. At
the surface, southerly winds prevailed through the Upper
Mississippi Valley and northern Great Lakes between a trough
through the eastern Dakotas and high pressure over the St.
Lawrence Valley. The WAA pattern through the region supported mid
clouds into Upper Michigan. Although there were weak radar
returns from MN into Upper Michigan, no pcpn was observed given
the very dry 925-700 mb layer.

Tonight, as the trough advances toward the region, moisture
advection toward Upper Michigan will increase as a sw low level jet
also approaches. Even with some time to saturate the dry layer,
expect light snow to develop over the west between 09z-12z with some
minor accumulations up to a half inch. Otherwise, increasing clouds
and mixing with the southerly winds will keep temps from falling
past the upper 20s.

Sunday, the mid level trough with weak to moderate 700-300 qvector
conv and a band of isentropic lift will bring pcpn through the rest
of Upper Michigan. Wet-bulb zero height forecasts suggest that most
of the pcpn will fall as snow, except over portions of the central
and east, especially for locations of with low level flow southerly
flow of the warmer waters of Lake Michigan. Overall amounts should
be fairly light with snowfall totals to around an inch possible. As
is often the case with WAA events, locations near Lake Superior
should see lower amounts with downsloping. Forecast soundings also
show enough drying at the top of the moist layer for the possibility
of freezing drizzle as the pcpn diminishes.

.LONG TERM...(Sunday night through Saturday)
Issued at 323 PM EST SAT NOV 16 2019

Sunday night, ongoing light precipitation will be associated with a
slow moving shortwave and cold front that will become negatively
tilted and eventually phase with a developing coastal low riding up
the Atlantic. Following that, a relatively progressive pattern will
be in place through next week with a couple passing shortwaves from
the W/WNW. On Thursday, confidence is beginning to increase that a
deepening sfc low will pass close enough to the southeast to bring
more significant precipitation, mainly over the east half, but exact
track and subsequent p-type and amounts remain in question at this
time. Except for a briefly colder airmass passing across the region
behind this system on Thursday night/Friday that will bring a return
to some LES, near normal temperatures are expected through the
period.

Early Sunday night, 850 temps of -2 to -4C will allow just enough of
a delta-T for a brief period of enhancement off of Lake Michigan,
but overnight qpf should still top out around 0.10". Early
on, some snow accumulations of up to 1" are possible east, however
forecast soundings do show ample mid level drying behind the
front, with a deep saturated low level profile that may remain
warmer than -10C. This indicates the chance of a changeover to a
period of drizzle/light rain that will possibly begin to freeze to
some elevated surfaces as temperatures dip into the upper 20s to
near 30. Although any ice accumulation would max out at a
couple hundredths of an inch, it could lead to some slick roadways
especially over the east half for the morning commute.

Cant rule out some lingering flurries or dz/fzdz during the day
Monday and into Tuesday as well, but little to no accumulation is
expected. 850 temps bottoming out near -5C will be too warm for any
sustained or significant lake effect snow. A shortwave and
associated rapidly weakening sfc trough will approach from the NW
Tuesday. Some light mixed precip is possible but there is some
uncertainty in timing and location. Only a dusting of snow or a
hundredth or so of drizzle/ice would squeeze out with a dry airmass
in place and very weak forcing.

Wednesday looks mainly dry as well, but an approaching upper trough
will bring colder air and increasing precipitation chances
overnight. There remains a rather large spread in ensemble solutions
but some synoptically forced precip is possible as a strengthening
sfc low pushes through lower MI, with the best chances currently
over the far east. Depending on the track, this could fall mainly as
rain, or bring measurable heavy wet snow to parts of the area, but
it`s also still within the envelope of GEFS solutions that
significant precipitation skips the UP entirely. Current
deterministic GFS is much slower and further west than other models
as well as the GEFS mean, so not buying into that much wetter soln.
Could be some lake enhancement component to this as well later
Thursday. Will continue to hone in on the details and impacts with
subsequent forecasts.

There is much higher certainty in a brief period of N to NW flow
lake effect behind this system Thursday night and Friday as a
pocket of -12 to -15C 850 temps pushes through, but the colder air
will be exiting through the daytime and winds should be
diminishing as well, so Friday night into Saturday will have better
chances of being drier. That said, the latest ECMWF brings a closed
low out of Ontario Sat, thus slight chance to low end chance POPs
remain in the forecast.
&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 527 PM EST SAT NOV 16 2019

An approaching trough and tightening pressure gradient will bring
gusty south winds to all sites through Sun morning. As low level
moisture increases along with light snow, expect conditions to drop
to MVFR overnight or early Sunday and to IFR Sunday morning.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 418 PM EST SAT NOV 16 2019

A strong pressure gradient ahead of an approaching trough will
support southerly winds between 20 and 30 knots. A few gusts up to
35 knots are possible into this evening, mainly at higher
observation platforms. The strongest winds are expected north and
along the Keweenaw and east towards the Canadian waters and
Michipicoten Island. Winds will veer more northwesterly and decrease
through the day on Sunday, relaxing below 20 knots by Sunday night.
Winds will remain relatively calm through Wednesday night as high
pressure remains across the region. Some models suggest a low
pressure system will develop across the Central Plains before
traversing northeast and cross Lake Superior Thursday night into
Friday. This will bring the next chance at winds approaching 30
knots.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...KCW
AVIATION...07
MARINE...JLB



...Updated Aviation Forecast Discussion...



 .DISCUSSION...
Issued at 230 PM CST Sat Nov 16 2019

The main forecast concerns are precipitation chances tonight into
Sunday morning, chances Sunday night into Monday, and then again
from Wednesday afternoon into Wednesday night and Thursday. The
last event in that list could have some thunder Wednesday evening,
then rain changing to snow. Some snow accumulations possible, but
way too early to start looking at specific amounts.

Short term...Tonight through Tuesday.
A fairly strong shortwave trough and an associated cold front will
continue to push eastward across the region tonight into Sunday.
This trough had 12 hour height falls of 50 to 100 meters from WY
up into Saskatchewan and Manitoba at 12Z. There was also decent
upper level jet support.

Cold front will continue to push through the area overnight, with
precipitation chances developing with mid level lift associated
with large scale forcing. Trough axis will not be through the
forecast area by 12Z and so had added some POPs for Sunday morning
with an update earlier today. Most model guidance is picking up on
the precipitation development in IA, but favored the RAP and some
of the other short range CAMs for precipitation later tonight into
mid morning Sunday across southeast NE (and southwest IA). This
looks to be mostly a rain event, with a light wintry mix at least
possible.

Another fast moving, but weaker, shortwave trough will bring a
chance for light precipitation late Sunday night into Monday
morning. This also looks to be mainly rain, with some brief
freezing rain or sleet possible.

Look for highs Sunday in the mid 40s to lower 50s, mainly 50s
Monday and Tuesday.

Long term...Tuesday night through Saturday.
At the start of this period we should be under the influence of
weak mid level ridging with a couple of troughs to our west. One
will be over Baja, with another stretching from the Pacific NW
into northern CA. This will transition to more of a split flow by
Wednesday, as a 500 mb low tries to close off near the CA coast.

Will start increasing chances for rain Wednesday afternoon, with
some thunder possible by Wednesday evening. The 12Z GFS model
showed some CAPE by that time across parts of southeast NE and it
does fit a common pattern. Several things will be coming together
for a moderate precipitation event for our area, with the heaviest
amounts likely farther south of our area, with better/deeper
moisture. Cold air moving in should bring a transition of rain to
snow, with details yet to be worked out. Just how fast the cold
air works in will help determine snow amounts. Best chances for
precipitation being in the form of snow are in northeast NE, but
at this time that is also where precipitation amounts (water
equivalent) are expected to be the lowest.

There are some fairly large model differences (GFS versus ECMWF)
for Thursday. The 12Z ECMWF has a much stronger shortwave trough
in the northern stream (and is colder) compared to the 12Z GFS.

The period from Thursday afternoon into Friday looks mainly dry,
with chances for rain and snow increasing again toward Friday
night and Saturday.

Temperatures should be fairly mild Wednesday, ranging from near 50
at the SD border to lower 60s at the KS border. Thursday will be
noticeably cooler with highs in the upper 30s to mid 40s. Highs
Friday and Saturday should be mostly in the 40s.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 531 PM CST Sat Nov 16 2019

Expect a wind shift across the area this evening and overnight as
a front moves across eastern Nebraska. In addition some lower
ceilings, MVFR, may occur along after midnight. At this point we
are not anticipating any visiblity issues as any precipitation
that does form will be very light and the wind gradient will
remain strong enough to keep any fog from forming.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

DISCUSSION...Miller
AVIATION...Pearson



Area Forecast Discussion

National Weather Service Riverton WY

 158 PM MST Sat Nov 16 2019

.SHORT TERM...(This evening through Sunday Night)

Storm system continues to move through the area this afternoon,
with the heaviest precipitation at 1 PM extending from around
Lander to Beaver Rim and eastward into Natrona County. HRRR is
showing the bulk of the precipitation moving southeast out of the
area by around 4 PM. Certainly some heavier rain and snow occurred
today than expected, with more snow due to adiabatic cooling from
southern Johnson County into Natrona County and across southern
Fremont County. Next couple of hours will see precipitation
continue across central WY and impact activities and travel.

Clearing and brisk north to northwest wind to the northwest of
the system is showing nicely on radar, satellite, and webcams,
though unstable mid layers with so-so moisture could give rise
some scattered showers. Skies will go from partly cloudy to mostly
clear overnight with mid-level northwest flow. Sounds like a good
pattern for areas of fog after midnight in the places that have
received the most precipitation. High- to mid-level clouds will
start moving back into NW WY by early Sunday morning as weak
energy overtops the upper level ridge over the western US. Models
are indicating that low- to mid-level moisture will increase
enough over NW WY for light snow showers Sunday morning. This
enhancement appears to be due to a shortwave trough moving through
the flow over Montana and NE WY. Sunday afternoon will thus see
the surface pressure gradient increase from west to east and help
west to southwest wind increase across southern and south-central
WY. The wave will also bring precipitation to northeast WY where
the Bighorns and Johnson County will see another round of
precipitation and wind shift to the north. With 700mb temperatures
back to around 0C, precipitation should be rain in the lower
elevations with snow levels around 8000 feet. Some showers may
make it down into eastern Natrona County as will late Sunday
afternoon. This moderately moist northwest flow will continue
Sunday night to allow light snow showers over the northwest
mountains through Monday morning.

.LONG TERM...(Monday through Saturday)

A weak ridge axis will build from west to northeast across the
forecast area to start out the work week. The southwest low to mid
level flow into the area will result in a couple of above normal
temp days with generally dry weather into Tuesday.  Winds will pick
up again on Tuesday especially in the wind corridor from Sweetwater
into Natrona counties and will have to be watched to potentially
have to highlight these areas.

The next storm system will arrive late Tuesday and affect northwest
Wyoming first, as the upper flow splits over the Pacific northwest.
This will result in an upper low being pushed south to California,
while the main mid level trough moves to the north of Wyoming. An
associated cold front will move southeast into the forecast area by
late Tuesday night, and will spread widespread precipitation into
the region through Wednesday.

The GFS and ECMWF models continue to disagree involving the precip
amounts with the next system. The GFS model continues to produce
more overrunning precip along the cold front, compared to the drier
solution of the ECMWF model. Still leaning more toward the ECMWF
model solution, which is more in line also with WPC QPF guidance,
which would result in more of a snow/rain mixture in the valley
locations and higher snow amounts in the northern toward central
mountains. This storm system has more of a pacific air component, so
do not expect very cold air in the wake of this system. High
pressure  By Friday, the slow moving frontal boundary should finally
be south of the state, with weak high pressure expected to build
into the forecast area through the upcoming weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)

West of the Continental Divide...KRKS, KJAC, KBPI, KPNA Terminal
sites:

Skies will be clearing across the area to start tonight`s forecast
period with all TAF sites expecting VFR conditions through the
entire forecast period through Sunday afternoon. Winds should begin
to relax somewhat by tonight after 03Z at most locations with the
exception of KRKS. Have increased winds at KRKS and KBPI after 17Z
Sunday.

East of the Continental Divide...KCPR, KLND, KRIW, KCOD, KWRL
Terminal sites.

Skies will be clearing across the area to start tonight`s forecast
period with most locations expecting VFR conditions through the
entire forecast period through Sunday afternoon. Winds should begin
to relax somewhat by tonight after 03Z at most locations with the
exception of KCPR. Due to the increased moisture available and
snowfall amounts especially at KLND and KCPR, will add in a mention
of fog overnight at these locations from 03Z-14Z Sunday.

&&

.FIRE WEATHER...

Storm system exiting the forecast area this afternoon, with
precipitation continuing across Natrona County, southern Fremont
County, and eastern Sweetwater County through about 4pm. Behind
the system, winds are north-northwest about 10 to 15 mph with
higher gusts. Skies will be partly cloudy to mostly clear
overnight. A weak system in northwest flow will skim north-central
WY from midday Sunday through Monday morning, bringing some
showers to the northwest mountains and the Bighorns, along with
showers over Johnson and eastern Natrona counties. Sunday will
also see slight warming over southwest WY with breezy west wind.
Weak high pressure will be over the area Monday and Tuesday for
continued breezy conditions and above normal temperatures.

&&

.RIW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...McDonald
LONG TERM...Troutman
AVIATION...Troutman
FIRE WEATHER...McDonald