Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/18/19

Area Forecast Discussion

National Weather Service Green Bay WI

 620 PM CST Sun Nov 17 2019

Updated aviation portion for 00Z TAF issuance

.SHORT TERM...Tonight and Monday
Issued at 251 PM CST Sun Nov 17 2019

The latest RAP analysis and satellite/radar imagery show an upper
trough moving across the northern Mississippi Valley early this
afternoon. This trough is pushing an occluded front across
Wisconsin, with areas of light precip occurring along the front.
After receiving 1 to 3 inches over parts of north-central WI this
morning, most of the light precip, including snowfall, has been
diminishing across the region. Patchy drizzle and freezing drizzle
have been showing up at times on area radars and surface obs over
northwest/north-central WI as mid-level moisture departs. Because
of previous snowfall and road temps above freezing, don`t think
freezing drizzle will have much impact through the afternoon.
Another area of rain is surging northeast over southern WI, and
should move into east-central WI later this afternoon.  Looking
further west, widespread low overcast prevails all the way to the
eastern Dakotas. As the front continues to move east across the
area, forecast concerns revolve around potential for freezing
drizzle/mist followed by cloud cover.

Tonight...The front will slowly move east across north-central WI
in the evening and northeast WI overnight. Steady light rain,
possibly mixed with snow, will depart east-central WI early this
evening. But forecast soundings indicate that the surface to
800mb layer will remain saturated along the front, so think
potential for drizzle and freezing drizzle will persist through
much of the evening. With cooling temperatures and loss of solar
insolation, the freezing drizzle may cause slippery spots may
develop on untreated roadways. Any wet roads may also develop some
black ice as temps fall below freezing. Otherwise, expect a low
overcast cloud deck to persist through the night, with not much of
a fall of temperatures. Lows ranging from the middle 20s to the
low 30s.

Monday...Widespread low clouds will continue into the morning. As
the surface ridge axis approaches during the afternoon, may see
some holes in the overcast develop, but not expecting much in the
way of clearing. Will only see a small rise in temps into the
middle to upper 30s.

.LONG TERM...Monday Night Through Sunday
Issued at 251 PM CST Sun Nov 17 2019

Mostly cloudy skies and generally dry conditions are anticipated
as a ridge of high pressure moves through Monday evening. A warm
front will impact the forecast area late Monday night into
Tuesday morning, but moisture and deep saturation will be limited.
Have raised pops to chance category, and gone with a light mix of
snow and freezing drizzle. Roads may be slippery in spots for the
Tuesday morning commute.

A stronger low pressure system is expected to arrive Wednesday
night into Thursday, and the GFS/ECMWF have come into better
agreement on a track through southeast Wisconsin. Low-level
thermal profiles and thicknesses would suggest rain across all but
the far northwest part of GRB CWA by early Thursday, with the
rain/snow line pushing southeast across all of north central WI
Thursday morning. Could see 1 to 3 inches of accumulation in
our northwest counties before the system pulls out midday
Thursday. Farther southeast, a good slug of moisture, with PWATs
exceeding 1 inch, will lead to moderate rainfall late Wednesday
night into Thursday morning, with rainfall totals possibly
reaching a half to three-quarters of an inch. With frost depths
already at 6 inches or more, runoff from the rain could cause
minor flooding issues. Have bumped up pops to likely/categorical
over the entire forecast area.

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

Models have come into better agreement for the weekend, with dry
northwest flow and a storm track remaining north of the forecast
area. Looks like a generally dry weekend, with temperatures near
seasonal normals.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 620 PM CST Sun Nov 17 2019

A mix of LIFR/IFR/MVFR CIGS and VSBYS were found across the area
during the early evening hours, with the poorest conditions across
central and north central WI, as a weak front crosses the state.
A wintry mix was also pushing across the area. Look for these poor
flying conditions to continue through the evening hours with a mix
of light snow, drizzle and freezing drizzle continuing. However,
as the front exits the area later this evening, CIGS/VSBYs are
expected to slowly improve from west to east overnight into
Monday morning, but conditions look to remain MVFR through at
least Monday morning. CIGS will climb close to or possibly into
low-end VFR range Monday afternoon. Winds will remain on the
light side through the TAF period.
&&

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

$$

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



Area Forecast Discussion

National Weather Service Louisville KY

 1006 PM EST Sun Nov 17 2019

.Forecast Update...
Issued at 1006 PM EST Sun Nov 17 2019

A sharp upper trough is entering the Mississippi Valley this
evening. Vorticity will increase in the base of the trough with a
maximum dropping into the Tennessee Valley during the pre-dawn
hours.

Upstream radars are showing targets aloft in mid-level clouds along
and ahead of the trough axis, but the hydrometeors are largely
evaporating as they fall into very dry sub-cloud air with dew point
depressions on the order of 20 to 30 degrees F. Since 22Z little
more than a trace to 0.01" of rain has been reported at southern
Illinois observation sites.

Will continue chances of sprinkles tonight in southern Indiana and
central Kentucky with a small chance of isolated measurable rain as
the trough moves into the region. As temperatures fall into the
lower and middle 30s by dawn a few flurries could mix in with the
sprinkles.

&&

.Short Term...(Tonight through Monday evening)
Updated at 320 PM EST Sun Nov 17 2019

An upper trough, now near the KS/MO border, will swing into our
region Monday morning. Moisture is limited ahead of this feature,
but a few models still are trying to squeeze out some light precip
for the morning hours and even into the afternoon hours east of I-
65, perhaps as a drizzle. Current forecast calls for slight chances
of measurable precip. We may have a brief window between the upper
clouds moving through and the lower clouds developing, as shown by
GFS and RAP time-height sections, to allow for a brief cool down
under calm/light winds. That window is 2-3 hours, according to those
models, but given upstream coverage on satellite, will lean towards
more cloud cover tonight. Even if we do end up with some wintry
precip/flurries road temperatures should be warm enough to quickly
melt it, given that rates would be very light.

Expect cloud cover to linger through much of the day Monday, making
for a dreary day. Despite that dreariness, statistical guidance is
calling for temperatures to reach the upper 40s and even a few 50s
across southern KY. Winds should turn to westerly for most areas by
afternoon, so not sure where the guidance is picking up on the
warmer values. That said, given that the spread is pretty narrow on
model solutions, will only cut down on the blended forecast by a
degree.

&&

.Long Term...(After midnight Monday night through Sunday)
Updated at 250 PM EST Sun Nov 17 2019

Another quick-moving wave looks to bring another low-end chance for
precip Tuesday. Precipitable waters are just a little higher with
this system but temperatures Tuesday morning may be a degree or two
closer to a point where we get some mixed precip early, mainly along
and north of I-64. It should be noted that the Euro and CMC
solutions show the QPF, whereas the GFS and NAM solutions are much
more spotty in coverage. Blended model guidance with some of the
better-performing 36-48 hour models of late and went with slight
chances for measurable precip. Soundings show that moisture is
fairly shallow, so we may end up with more of a measurable drizzle
than rain/snow. Also, not expecting any travel impacts here, as in
the Monday morning case, with road temps still well warm enough.

Midweek offers us a brief break from these precip chances, as well
as a warmup as ridging builds in aloft. That will be short-lived
however as a stronger low pressure system moves across the Midwest
Thursday. These rain chances could linger into Friday as the
associated cold front briefly stalls somewhere in the vicinity of
the Ohio Valley and then gets another upper trough to kick it out
either Friday or Saturday. Model guidance diverges quite a bit with
the timing here, so will have to spread out timing for precip in
these periods. Type is in question given that spread, but as with
previous forecast, qpf ended up more in the liquid variety with this
set of blended guidance.

&&

.Aviation...(00Z TAF Issuance)
Issued at 650 PM EST Sun Nov 17 2019

Current satellite imagery shows high clouds streaming across the
region, with VFR conditions expected to prevail for the beginning of
the TAF period. Ceilings will begin lowering into MVFR range at KHNB
around 10Z and push eastward towards the other TAF sites throughout
the day as an upper level trough swings across the OH Valley. Some
light precip will be possible tomorrow, but confidence is too low to
include any mention in the TAFs. Ceilings will begin to lift above
fuel-alternate and into VFR towards the end of the TAF period.
Expect a more westerly wind tomorrow, generally under 10kts.

&&

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

$$

Update...13
Short Term...RJS
Long Term...RJS
Aviation...JML




Area Forecast Discussion

National Weather Service Marquette MI

 524 PM EST Sun Nov 17 2019

.SHORT TERM...(This evening through Monday)
Issued at 427 PM EST SUN NOV 17 2019

Latest WV imagery and RAP analysis indicated an upstream mid/upper
level trough from northwest Ontario into the Upper Mississippi
Valley. At the surface, southerly winds prevailed ahead of the
associated sfc trough through western Lake Superior into northwest
Wisconson. The combination of weak isentropic lift and 700-300
qvector conv ahead of the mid level trough supported light snow/rain
over mainly the east half of Upper Michigan. With the pcpn
diminshing over the west, upstream obs indicated the potetnial of
some light drizzle or freezing drizzle as moisture above -10C
dwindles.

Tonight, with abundant low level moisture over the region and weak
qvector conv and low level conv near the trough, patchy dz/fzdz is
expected to continue this evening over the west. The best chance for
some icing will be in the higher terrain west where upslope westerly
flow develops this evening. Over the east, the pcpn will also
gradually diminish but may linger a bit longer where some lake
enhancement is possible with southerly flow off of Lake Michigan.
Temps should remain high enough for pcpn to remain as light rain or
drizzle.

Monday, some lingering light pcpn may linger over the east as the
mid level trough will be slow to exit the region. With only a
shallow moist layer, mainly just dz/fzdz is expected. Otherwise, look
for seasonable November temps with highs in the mid to upper 30s
under cloudy skies.

.LONG TERM...(Monday night through Sunday)
Issued at 338 PM EST SUN NOV 17 2019

Some light, scattered precipitation is possible Tuesday as a
weakening shortwave traverses the region. Wednesday looks mostly dry
but all eyes are on the potential for the first widespread system
snow this winter as a low will eject out of the panhandles region
and head northeast Wednesday evening. The sfc circulation will be
strengthening Thursday as a mid-level, positively tilted trough digs
out of the northern Plains. Models continue to come into better
agreement on a track that favors significant synoptically driven
precipitation across the Upper Peninsula, but there remain questions
about the strength of the low and extent of the cold air and thus
precipitation types. Better agreement exists in a brief period of NW
wind lake effect snow following this system through much of Friday,
shutting down Friday night. Then, another shortwave pushing
southeast through Ontario may clip the region with more light snow
chances late Saturday into Sunday, especially east.

Monday night into Tuesday, as a weakening shortwave trough axis
approaches from the WNW, some light mixed precipitation is likely
for portions of the area. Best chances are over the far west with
additional slight chances over the far east. A quick dusting of snow
will very likely be followed by a brief period of drizzle/freezing
drizzle as mid-levels dry out a little and scour out ice nuclei.
Could be a couple hundredths of sfc ice accumulation, just enough to
potentially cause some slick spots on roads and sidewalks for the
Tuesday morning commute. Best chances for this will be in Gogebic
and Ontonagon Counties.

Wednesday brief ridging will poke into the region from the SE, but
this will be short lived. NAM shows a much faster progression of an
initial round of isentropic lift and associated precip that could
affect the west half in the afternoon but chances are good that this
will hold off until the evening or overnight.

The main event for this week will be the deepening low pushing
through IA into WI Wednesday night, with a precipitation shield
filling in through the early AM hours of Thursday over the UP and
then exiting in the afternoon. Model agreement in the track is much
better than yesterday, but significant differences remain in the
sensible weather. While the GFS/ECMWF would suggest low level
temperatures supportive of mainly rain except across the far west,
the GEFS ensembles are trending colder and generally produce more
snow. In fact, at MQT the deterministic soln is at the very bottom
of the 12Z GEFS snow envelope. The main exception is that east of US-
41 in all likelihood more rain will mix with the snow regardless. If
snow were to be the more dominant precip type across central/western
portions of the region, it would be of the heavy and wet variety. On
the high end, 6-9" snowfall accumulations wouldn`t be out of the
question in some spots, but there remain several model solutions
that keep the majority of the precip in liquid form and thus only
produce a couple of inches of snow mainly west on the backside of
the system as cooler air moves in. Hopefully things will become
clearer as we add higher resolution models to the mix over the next
24-48 hours.

Some NW wind LES is likely Thursday night and Friday as winds
strengthen and 850 temps drop to somewhere in the -11C (ECMWF) to -
14C (CMC) range. But this will be cut off quickly on Friday
afternoon over the west and evening east as mid-level shortwave
ridging pushes the trough axis eastward and winds shift back to the
SW. Could be some additional light snow returning as early as
Saturday afternoon, mainly east, but marginally better chances will
come overnight and Sunday.
&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 524 PM EST SUN NOV 17 2019

With abundant low level moisture over the region as a trough moves
through, expect mainly IFR or low end MVFR conditions to prevail
through tonight. Some freezing drizzle may also be possible at CMX
where upslope westerly flow develops. Enough dry air moves in Monday
for conditions to lift to MVFR, first at IWD.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 414 PM EST SUN NOV 17 2019

Lingering gusty winds of 20-30 knots over the far eastern lake will
continue to diminish this evening. Winds will veer more west to
northwesterly and decrease further into Monday, relaxing below 15
knots. Winds will remain relatively calm through Wednesday night as
a trough hangs over the area followed by a brief ridge. Models then
indicate a low pressure system will develop across the Central
Plains and lift northeast toward Lake Huron Thursday evening and
then into Quebec on Friday. This will bring the next chance at
northwest winds approaching 30 knots, and possibly exceeding 30
knots over the eastern lake by Thursday evening. Winds will then
gradually subside below 20 knots early Friday morning.
&&

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

$$

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