Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/31/18

Area Forecast Discussion

National Weather Service Green Bay WI

 909 PM CST Tue Jan 30 2018

New Information added to update section

.UPDATE...
Issued at 902 PM CST Tue Jan 30 2018

Backed off on pops a bit for the late evening and early overnight
hours, then increased pops over northern WI later tonight into
Wednesday morning. Also increased QPF and snowfall amounts a bit
over the north, and especially far northeast WI. There is some
concern that a winter weather advisory may be needed for Door
county (for 2-4 inches of snow north of Sturgeon Bay), but
confidence is just a little too low to pull the trigger on it at
this time.

We upgraded our small craft advisory to a gale warning earlier
this evening, after coordination with MKX. Gusts are already
pushing 30 kts, and we should get occasional gusts to 35 kts
overnight.

&&

.SHORT TERM...Tonight and Wednesday
Issued at 243 PM CST Tue Jan 30 2018

The latest RAP analysis and satellite/radar imagery show a strong
area of low pressure passing across the Saskatchewan/Manitoba
border early this afternoon. In the warm advection ahead of the
low, mid-level fgen is producing an area of light to moderate
snow which is crossing into NW WI. This band of snow remains on
track to move into the Vilas-Wood county corridor between 3 and 4
pm and the I-39/route 51 corridor between 4 and 5 pm. A quick half
inch to inch of snow could fall right at evening commute time which
could make for some slippery roads, so will issue a SPS. A cold
front trails the low over NW ND, and will arrive late tonight.
Forecast concerns mainly revolve around light snow chances and
trends.

Tonight...A strong cyclone will track east across Manitoba and
Ontario tonight and Wednesday. The RAP and HRRR agree that mid-
level fgen in the warm advection zone ahead of the cyclone will
push a band of light snow across the area from late this afternoon
through about mid-evening. Because the band will be moving east
relatively quickly, mainly looking at around a half inch of
accumulations, though isolated locations over northern WI could
see up to an inch. Forcing with the tail of the main shortwave and
along a weak surface cold front will then generate a second band
of light snow after midnight across north-central and northeast
WI. An inch or two of snow is possible across the north, with
lesser amounts in central and east-central Wisconsin by morning.
With the clouds and gusty southwest winds, temps will be
considerably more mild tonight that yesterdays readings, and range
from the mid teens in the north to mid 20s south. Not much of a
change from todays high temps.

Wednesday...The light snow will be exiting northeast WI during
the morning. Up to an additional half inch will be possible over
Door county. Combined with the snow that will fall tonight, slick
roads can be expected for the morning commute. Behind the front,
drier air will invade the region from the northwest to southeast
from about mid-morning through early afternoon. Should therefore
see ample sunshine in the afternoon with highs ranging from the
mid 20s in the north to mid 30s in the south.

.LONG TERM...Wednesday Night Through Tuesday
Issued at 243 PM CST Tue Jan 30 2018

Very cold wind chills and the prospect of snow for
Friday night and Saturday are the primary weather concerns for this
period. A strong upper trough will swing across the area Wednesday
night accompanied by a cold front at the surface. The air is dry
but there should be sufficient support for light snow. The NAM and
ECMWF look on the right track with this, while the GFS is dry.
Think around an inch is likely.

The cold front will be followed by much colder air Thursday and
Friday. Wind chill advisories are likely north and west of the Fox
valley Thursday night.

Surface waves moving northeast along an arctic cold front should
bring some snow Friday night and Saturday. Model differences are
too big to determine exact snow amounts, but a few inches look
possible. Even colder air will arrive Saturday night and with a
fresh snow cover temperatures should fall below zero across the
entire region. Wind chill warnings and advisories look likely.
Temperatures could remain below zero from Saturday night through
midday Monday in far northern Wisconsin.
&&

.AVIATION...for 00Z TAF Issuance
Issued at 538 PM CST Tue Jan 30 2018

A band of snow with MVFR/IFR conditions will quickly shift east
through the forecast area this evening, and should taper off
within the first hour of the TAF period at the western sites, and
during the mid to late evening in eastern WI. A lull in the snow
and mainly mid-level clouds will occur late this evening into
early overnight. Then additional snowfall with MVFR/IFR conditions
will develop along a cold front late tonight into early Wednesday
morning. MVFR ceilings may linger for a few hours after the snow
ends Wednesday morning, but partial clearing and VFR conditions
are anticipated for the late morning and afternoon.

LLWS will overspread the entire area through mid-evening, then
ease from west to east late tonight into early Wednesday.
&&

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

$$

UPDATE.........Kieckbusch
SHORT TERM.....MPC
LONG TERM......RDM
AVIATION.......Kieckbusch




Area Forecast Discussion

National Weather Service Lincoln IL

 849 PM CST Tue Jan 30 2018

.UPDATE...
Issued at 840 PM CST Tue Jan 30 2018

Latest satellite data indicating a large area of mainly high level
clouds across the region this evening in advance of a frontal
boundary that will push across our area on Wednesday. A tightening
pressure gradient from the departing high pressure system that
brought the cold weather to our area this morning and low pressure
tracking just north of Minnesota this evening has brought gusty
south winds to central Illinois. A few gusts around 35 mph have
been reported early this evening and expect that to continue
overnight. That, coupled with the extensive shield of high level
clouds, will keep temperatures steady or even rise a few degrees
overnight. Not looking that favorable for viewing the lunar
eclipse towards dawn on Wednesday as the cirrus shield extends
west of the Missouri River this evening. The HRRR does indicate
a few breaks develop in that band of clouds over central Illinois
late tonight but based on what we are looking at on the IR loop
this evening, not looking that promising at this time.

As the cold front moves across the area, the stronger winds should
translate into eastern Illinois during the morning with rather
mild temperatures expected as highs top out in the upper 40s north
to the lower 50s over southwest Illinois. Colder weather moves
back into our area later Wednesday and for the rest of the work
week with early morning lows on Friday dropping back into the
single digits over all but far southeast Illinois. Made some minor
adjustments to the wind/wind gusts this evening, but for the most
part, the grids are in great shape. As a result, no ZFP update
will be needed at this time.

&&

.SHORT TERM...(This evening through Wednesday)
ISSUED AT 320 PM CST Tue Jan 30 2018

The short term will be highlighted by increasing southerly winds
tonight into tomorrow morning, as a 60KT southwesterly low level
jet (LLJ) cranks up in the 2-4K FT layer. The surface pressure
gradient will be tightening up over night, as high pressure
departs to the southeast of IL and a low pressure system
approaches from the Plains. Sustained south winds look to climb
into the 15-25 mph range, with gusts of 30-35 mph at times after
midnight and into Wed morning. The combination of strong south
winds and gradually warming low to mid levels will create a non-
diurnal temperature profile overnight. Low temps will most likely
be in the evening, with temps either steady or slowly rising as
the night progresses. Evening lows tonight will be in the upper
20s to low 30s, with temperatures by 6 am in the low to mid 30s
and climbing.

A warm front is expected to lift to the northeast across Illinois
Wed morning, to aid in the warm-up. Despite 850 mb temps peaking
in the 4-6C range just before sunrise then falling off slightly
during the day, high temps should be able to climb into the upper
40s to low 50s. South wind gusts will begin to subside from west
to east Wed afternoon, as the cold front progresses to near I-72
by 6 pm, and the surface pressure gradient weakens. Previous
model runs had some sprinkles developing as early as Wednesday
afternoon, but the 12z models have delayed much in the way of
precip until after midnight Wed night.

.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 320 PM CST Tue Jan 30 2018

The cold front is expected to stall out just south of our southeast
counties Wed eve, and a 500 mb vort max is expect to progress
east along the front. That will help create some forcing for
precip in our east counties between midnight and 6 am, and for
areas south of I-70 Thursday morning. We have narrow areas of slight
chance and chance PoPs /15-30%/ from late Wed night into Thursday
afternoon. Precip type looks to start out as a mix of rain and
snow or all snow Wed night, then transition to all rain as temps
warm on Thursday. Flurries could develop well north of the front
Wed night into Thur morning, north of I-74 where another 500mb
wave pushes across northern IL. Overall, little to no snow
accumulation is expected from this system, as the better forcing
for precip has continued its southerly trend.

A cold blast of air will follow that front, as Arctic high
pressure builds into Illinois. Low temps Thurs night will drop
into the single digits north of I-70, with low teens south of
I-70. The other issue Thursday night into Groundhog Day morning
will be gusty northwest winds of 10-20 mph putting wind chills
down to -5 to -10F.

A transition to southerly winds Friday afternoon will begin a
brief warming trend into Saturday, before another strong cold
front pushes across IL Saturday night. Highs Saturday should climb
to near normal for early February, but a reinforcing push of cold
air will change the last half of the weekend into early next week.
The cold front looks to have enough F-gen forcing for light snow
to progress across Illinois Saturday afternoon and Sat night.
Snow amounts look to remain light, with a half into to an inch for
areas along and north of I-74, and lesser amounts the farther
south of I-74 you go.

High pressure should provide dry conditions for Sunday and
Monday, along with below normal temperatures. Lows Sunday night
may drop to colder numbers than Thursday night, especially if any
snow cover remains into early next week.

Another shortwave could trigger light snow late Monday afternoon
through Tuesday, with some light snow accumulation possible.
However, there are large differences in position and track of the
weather features, so PoPs were kept low for now.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 515 PM CST Tue Jan 30 2018

Main forecast concern will be with the LLWS threat tonight into
Wednesday morning. Forecast soundings and time height cross
sections indicate 45-55 kt winds between 1500-2000 feet tonight
into Wednesday morning out of the south to southwest. We look for
the winds to gradually subside after 16z Wednesday as a frontal
boundary approaches the forecast area during the day. Mainly some
VFR mid and high level clouds around tonight and Wed with surface
winds gusty out of the south at 12 to 17 kts with gusts up to 25
kts. Surface flow will then veer into the southwest and west as
the front approaches Wednesday morning with speeds decreasing to
10 to 15 kts after 18z.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...Smith
SHORT TERM...Shimon
LONG TERM...Shimon
AVIATION...Smith




Area Forecast Discussion

National Weather Service Marquette MI

 1020 PM EST Tue Jan 30 2018

.UPDATE...
Issued at 1020 PM EST TUE JAN 30 2018

So far, fcst appears to be on track. WAA/isentropic ascent generated
band of snow is quickly spreading e across the area. This snow is
generally on the light side, but there should be some enhancement
off Lake MI over the eastern fcst area as the snow progresses
eastward. This snow should then tend to diminish for a while
overnight. Of a bit more concern is the pcpn breaking out across
mainly SD recently. This pcpn is tied to a shortwave and more
importantly to the left exit of 130kt upper jet streak. 00z NAM and
hourly RAP runs this evening show a rather impressive upper
divergence signature taking shape across central and eastern Upper
MI late tonight/Wed morning as nose of this upper jet shifts e to WI
by 12z Wed. It appears there will even be some coupling with the
right entrance of a 100kt upper jet streak located ne of Lake
Superior, boosting the upper divergence depicted by the models.
NAM/RAP/HRRR show a corresponding increase in qpf over the central
and eastern fcst area early Wed morning. So, may see 1-2hrs, maybe
3hrs, of mdt/hvy snow in the 6am to 10am time frame across the e
half of the fcst area, just in time for the morning commute. Thus,
ongoing advy over the eastern fcst area appears on track.
Dickinson/Marquette/Menominee counties will also be impacted by the
intensifying area of snow. Increased snow amounts some in these
counties. Given the timing of the snow in this area just before and
during the morning commute, may need to consider an advy issuance
for these 3 counties later in the night, depending on how upstream
developing pcpn evolves over the next several hrs.
&&

.SHORT TERM...(This evening through Wednesday)
Issued at 410 PM EST TUE JAN 30 2018

WV imagery and RAP analysis indicated nearly zonal mid/upper level
flow from the Pacific Northwest through the n cntrl CONUS. A
vigorous shortwave trough extended from n cntrl Manitoba into the
nrn plains. At the surface, a trough extended through the cntrl
Dakotas from a 988 mb low over w cntrl Manitoba. Radars/obs
indicated a band of snow from ne MN into wrn WI supported by strong
WAA 285k-295k isentropic lift ahead of the trough. Otherwise,
mid/high clouds were thickening across Upper Michigan ahead of the
snowband.

Tonight into Wednesday, models and radar trends suggest that the
initial snow band will move across the cwa this evening with a lull
overnight before the snow increases again from 06z-09z as 700-300 mb
qvector conv associated with the Dakotas shrtwv moves in. Overall
snow amounts should remain in the 1 to 3 inch range over most of
the cwa. However, lake enhancement with srly flow off of Lake
Michigan will bring the potential for heavier snow in the 3 to 7
inch range, especially east of a line from Manistique to Grand
Marais. There is still some uncertainty with the additional
amounts given the limited instability (850 mb temps near -9C)
amount of 900-700 mb directional shear, and steady eastward
movement of the greatest low level conv btwn 06z-15z. So, the
winter wx advisory was maintained. Expect the snow to quickly end
from west to east in Wed morninng.

Blustery west winds will then develop, especially over the Keweenaw
where gusts to around 45 mph (advisory), per momentum transfer prog,
will be possible as CAA increases mixing depth. Although temps will
remain steady or slowly falling over the west, highs should still
reach 30 or the lower 30s, central and east.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 353 PM EST TUE JAN 30 2018

General trend in the extended part of the forecast will be much
colder temperatures along with intermittent chances for lake effect
snow. Additionally, wind chill values will approach or drop lower
than thresholds for wind chill advisory criteria most morning
through the extended.

A steady/reinforced overall troughing pattern will continue through
the extended forecast over much of the eastern CONUS. The main
targets for the more concentrated lake effect/enhanced snow will be
the west to northwest wind favored snow belts through next Tuesday.
850mb temperatures are expected to fall from around -15C to -20
Wednesday to the -20C to -25C range through the rest of the
extended. This again is favorable for lake effect/enhanced snowfall
through much of the extended. There are a couple periods where lake
effect snow may intensify, which would be Wednesday night into
Thursday, Friday night into Saturday and again Monday night into
Tuesday. This will be associated with stronger shortwaves rotating
through the overall troughing pattern in place. There may be more
subtle waves that enhance the snowfall at times, but these will have
to be pinned down with more confidence as models grasp these
features over the next several days. Otherwise, temperatures will be
roughly 10 to 15 degrees below normal for both highs and lows
throughout the extended forecast.

Wind chill values will approach advisory criteria for most mornings
in the extended with values approaching or dropping below the -15F
to -25F range.
&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 655 PM EST TUE JAN 30 2018

Approaching disturbance will spread a couple of bands of snow across
the area tonight into Wed morning along with gusty south winds and
LLWS. Conditions at KCMX/KSAW will likely fall to IFR or near IFR
for a brief time this evening. Otherwise, MVFR conditions should set
in. Snow will be lighter at KIWD with mostly VFR conditions expected
until late tonight when MVFR conditions should develop. On Wed, MVFR
conditions should prevail at KCMX, but with gusty w winds up to
around 35kt, -shsn/blsn could lead to periods of IFR. KIWD/KSAW
should see a period of VFR conditions during Wed in the wake of
cold fropa.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 410 PM EST TUE JAN 30 2018

Long period of gales is expected starting this evening as south
gales tonight shift to the west on Wednesday. Gale warnings run from
tonight through Thursday afternoon. Heavy freezing spray is expected
Wednesday night into Thursday night.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until noon EST Wednesday for MIZ006-007-
     013-014-085.

Lake Superior...
  Gale Warning until 4 PM EST Thursday for LSZ264>267.

  Gale Warning until 1 AM EST /midnight CST/ Thursday for LSZ162-
     263.

Lake Michigan...
  Gale Warning until 1 PM EST Wednesday for LMZ248-250.

&&

$$

UPDATE...Rolfson
SHORT TERM...JLB
LONG TERM...KEC
AVIATION...Rolfson
MARINE...JLB