ILSNOW

And the GFS FV3

Heres 10:1 H

Has the GFS-FV3 ever been correct??

18z NAM to hoosier's point becoming a little icer at ORD

Euro 72 hrs 1000mb low over central IL

12Z models have pretty much held serve with the american models cutting the low farther west then the foreign models below is the GFS FV3

MKE take The operational 00Z GFS is furthest north, taking the 850 low across central Wisconsin. The ECMWF, on the other hand, takes the low across Chicago, which is an ideal track for a winter storm across southern Wisconsin. Between these two is the GFS Ensemble mean, which lends some credence to a more southerly track. Either way, winds will increase considerably heading into Tuesday morning, as the low deepens quite rapidly.

Euro 997 hr 72 at central KS/OK border to 985 hr 96 eastern shore of lake mich near new buffalo

Its the NAM but now showing more of an ice event on 0Z vs 18Z

Light freezing rain started 20 minutes ago streets are a sheet of ice already it’s 29

CMC

snippet from Izzi Model guidance isn`t in perfect agreement on the placement of the sfc freezing line and that has big implications on where the greatest risk of icing will exist. Using the typically more reliable models would lead me to believe that the great risk area could be from Lee/Ogle/northern LaSalle counties east-northeast into the western and northern suburbs of Chicago. While I am concerned that there is a potential for ice accums of at least 1/4" to 1/2", my confidence isn`t high enough in placement or chance of occurrence to make any changes to going headlines or forecast ice accums.

18Z NAM is wetter and taken at face value (which we won’t) is a big ice storm for far northern IL, N central and NW IL

12Z models continue to warm for Wednesday night Thursday event.

long range 84 NAM (for what little that it is worth)

OZ Euro step in the right direction @ 144hr 996 over Chicago

Nice LOT update

O’Hare not budging from -16 the wind is still up tying or breaking the record going to be tough

actually updated to this

Snow has started here as well.

GFS not backing down

LOT update National Weather Service Chicago/Romeoville, IL 901 PM CST Sun Jan 27 2019 .UPDATE... 901 PM CST Winter storm continues to take shape to our northwest this evening. Latest guidance continues to support a several hour period of heavy snow across the area last tonight and very early Monday morning, with snowfall rates of an inch or more per hour likely especially across far northern Illinois. Had considered adding another tier of counties to the Winter Storm Warning along the I-88 corridor, though 00Z runs of the HRRR/NAM and 3km WRF all appear to support going headline delineation with respect to expected snowfall amounts. Main message continues to be that several inches of snow will come at bad time for Monday morning commuters, and that the morning rush will likely be significantly impacted especially north of I88. Evening GOES-16 water vapor imagery depicts a vigorous mid-level short wave trough digging southeast across the northern Plains. Strong surface pressure falls, in excess of 4 mb per 3 hours, were developing downstream into the mid/upper Mississippi Valley in response to strong low level warm advection and height falls. This in turn was resulting in an expanding precipitation shield across much of Minnesota and Iowa, and into western parts of Wisconsin and Illinois. Model guidance has locked into a solution which takes the track of the surface low southeast into central Iowa through midnight, then eastward across far northern Illinois near the Wisconsin border through Monday morning. This low track would typically not favor heavy 6+ inch snowfall amounts for northern IL. However, very strong baroclinicity and dynamics with this system in addition to the initial southeasterly propagation of the storm support a period of impressive snowfall rates across northern IL. In addition, presence of cold arctic air mass will also likely support higher than usual snow/liquid ratios during the period of strong isentropic ascent from around midnight through sunrise. Overall, tweaked QPF amounts and snow ratios slightly, though basically am maintaining the same forecast snowfall amounts ranging from 1-3 inches across the southern couple tiers of counties to 6 to 9 inches across far northern IL closer to the Wisconsin border. The heaviest snow should be winding down as the morning rush hour begins, with intensity tapering of from sunrise through mid- morning. Mid-level dry slot develops which will likely result in a period of mixed light snow or drizzle. Surface temps, which will rise through the night and into Monday morning, will bring temps slightly above freezing across the east/southeast parts of the cwa for a time, though temps will then fall as the low and cold front move east of the area by early afternoon. This will result in the potential for a period of light freezing drizzle before cold advection cools the column enough for any lingering precip to change back over to light snow/flurries. Winds gusting 30-35 mph initially from the south in the morning, and then from the west- northwest in the afternoon, will likely cause some blowing and drifting of snow especially in open areas. Temperatures will fall into the teens and lower 20s behind the departing system in the afternoon, with wind chills dipping toward zero by nightfall.

nice for Milwaukee Changes to the forecast include an hour or two later snow arrival time this evening. Increased snowfall between 6 AM and Noon on Monday. Snow will gradually enter from west to east this evening and warm advection aloft kicks into gear at the nose of a 45kt low level jet. HRRR/RAP have come into line with GFS/NAM/ECMWF/GEM with the surface low strengthening and track. With the majority of the area north of the low track that goes across northern Illinois, we are poised for significant snow accumulation. QPF output remains robust, suggesting 1 to 2 inch per hour snow rates overnight through the mid morning hours Monday. This will cause significant travel impacts, with substantial impacts to the Monday morning commute. All areas can expect at least 6 inches of snowfall with a widespread 6-10 inches forecast. The axis of highest snowfall, between 10 and 14 inches is focused on the northeast portion of the forecast area, including areas in and around Fond du Lac, Sheboygan, Port Washington, West Bend and Juneau. It is entirely possible this band of higher snow shifts just a bit to the south and includes the the I-94 corridor. Bottom line, widespread heavy snow is expected. Lake enhancement will likely add 2-4 inches for lake front counties overnight through mid Monday morning. Right now, Sheboygan, Ozaukee and Milwaukee are most prone to these higher amounts. It is not out of reason to see storm total snowfall around 18 inches where lake enhancement is maximized.