Marine Forecasts

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7 Day Forecast for Marine Location Near Evanston, IL

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Area Discussion for - Chicago, IL

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FXUS63 KLOT 121814 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 1214 PM CST Thu Dec 12 2019

SHORT TERM. 300 AM CST

Through Friday .

Today will find temperatures jump 15 to 20 degrees from yesterday thanks to gusty southerly winds expected to sporadically peak near 35 mph. Apart from a chance of sprinkles/spotty light rain in the far north, through the day Friday looks dry for most if not all of northern Illinois and northwest Indiana.

Early morning satellite water vapor imagery reveals a mid-level circulation across the Dakotas headed quickly east-southeast. This will pivot more due east in southern Minnesota into Wisconsin as it rounds the larger scale long wave trough across the eastern half of Canada. With this feature impinging quickly on the modified arctic air mass, this has limited time for any moistening in its warm sector, and that's why any afternoon/early evening brief light rain or sprinkles should be confined to near the Wisconsin state line associated with a 60+ kt low-level jet. It's this return flow that will be the story for the area, with sustained southerly winds near 20 mph thanks to a large surface isallobaric component. Given the unlikely scenario of any lower base clouds, would expect the boundary layer while shallow to still be able to mix gusts occasionally to the top of the mixing channel of 35 mph shown by the RAP and GFS.

By advection alone, temperatures will climb into the 40s with high confidence for most of the CWA, apart from toward Rockford where readings may stay just shy of that due to the thickest mid-level clouds. The question is just how far into the 40s. Some limited snow cover in the Illinois and Vermilion River Valleys should sublimate fairly quickly today and there is some guidance indication that the southeast CWA sees some thinning of high-mid cloud cover offering some sun. For now have gone primarily mid 40s, trying to balance the fact that the day after a heart of an arctic mass often can run a little cooler than guidance, though those often have widespread snow cover.

The clipper's associated low-level trough/cold front will move into the CWA late tonight and gradually weaken through Friday. Clouds should start to thicken and gradually lower Friday in a slowly moistening mid to low levels, but forcing for precipitation looks limited. In the absence of any advection and with clouds, high temperatures look to peak upper 30s to 40.

MTF

LONG TERM. 325 AM CST

Friday night through Wednesday .

An unsettled pattern will be in place Friday night through Monday, with Monday having some signal for accumulating snow maybe more so along/south of I-80, but that is with low confidence. For the beginning of this time (Fri night into Sat), the precipitation intensity looks light and coverage potentially limited, so impacts look to be small. The one main caveat to that is that there is a limited chance of freezing drizzle later Friday night and early Saturday morning.

A pseudo-split flow regime Friday night into Saturday will see multiple slow-moving short waves in the region, with guidance favoring the southern stream jet to drive some phasing of this activity east of the region into Saturday night. This presents limited deeper upper jet support in the region, as well as minimized areas of focus/convergence/baroclinicity in the lower to mid levels. On Friday night, any precipitation looks light and associated with either very weak isentropic upglide or pockets of ascent ahead of/within any of the mid-level impulses. Profiles show some marginal saturation of the heterogeneous ice nucleation layer, but also have doubts there will be precipitation actually occurring in such a profile. So while drizzle/freezing drizzle is possible it is again low confidence. Equally if not slightly more likely if any precipitation occurs is that it may be patchy very light snow/flurries. Lows on Friday night/Saturday morning have consistently looked like they would be right around freezing.

With the strengthening low expected to the east into Saturday p.m., cold advection will gradually strengthen over the area with still some impulses rotating through. So some potential for light snow Saturday and depending on how temperatures fall out, could see some very light accumulation. Anything higher than that is a diminishing forecast outcome at this point. The shot of cold advection will bring wind chills into the single digits during Saturday evening persisting into Sunday morning.

A continued quasi-split flow pattern rides into the start of next week. Guidance is in sound agreement on a southern stream system anchored along the subtropical jet and amplifying somewhere in the eastern half of the country on Monday. The ECMWF has been consistently south with this while the GFS has been frequently further north over a larger part of the CWA on its solutions. The GFS ensemble does have some more members that have trended north this past 24 hours, and a majority of them are producing some snow in the southeast forecast area as the system matures. For now have only inched up blend-provided chances in the southeast CWA, but tough to stray much from the consistent ECMWF solution at this medium range distance. Will be a period to watch as a swath of accumulating snow is certainly possible somewhere in the Ohio Valley to southern Great Lakes region.

Beyond looks somewhat quiet as northwest flow aloft takes back over for at least a multi-day period. Temperatures should be slightly below normal, though if any snow cover materializes that would likely tilt the forecast colder.

MTF

AVIATION. For the 18Z TAFs .

Low pressure across northern IA will shift into Wisconsin this afternoon and will continue the gusty south winds across the terminals. A strong inversion will limit the strength of gusts at the surface but lower 30 kt gusts have been observed and should remain the case this afternoon. Cannot rule out stray gust to 35 kt which would impinge on the ORD cross runway threshold, otherwise expect LLWS through the afternoon with 50-55 kt at 2000 ft. Speeds will taper off this evening as will the magnitude of the LLWS.

Lower VFR or some MVFR ceilings may impinge on the area this evening and overnight, with a bit higher confidence toward RFD and to the the west of ORD/MDW Friday morning.

KMD

LOT WATCHES/WARNINGS/ADVISORIES. IL . None. IN . None. LM . Small Craft Advisory . IN nearshore waters until midnight Friday.

Small Craft Advisory . IL nearshore waters until 9 PM Thursday.



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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
CHII2 - Chicago, IL	10 mi	35 min	SSW 29 G 32	43°F				28°F
CNII2	13 mi	25 min	S 17 G 24	43°F				25°F
CMTI2 - 9087044 - Calumet, IL	22 mi	55 min	S 13 G 23	42°F			1020.4 hPa (-4.4)	28°F
KNSW3 - Kenosha, WI	39 mi	55 min	SSW 15 G 20	43°F			1018.6 hPa (-4.4)
MCYI3 - Michigan City, IN	46 mi	35 min	S 20 G 26	41°F				26°F

Wind History for Calumet Harbor, IL

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Chicago / Wheeling, Pal-Waukee Airport, IL	12 mi	63 min	S 20 G 31	10.00 mi	Overcast and Breezy	44°F	24°F	45%	1020.7 hPa
Chicago, Chicago-O'Hare International Airport, IL	12 mi	64 min	SSW 13 G 27	10.00 mi	Overcast	42°F	26°F	53%	1020.5 hPa
Chicago, Chicago Midway Airport, IL	17 mi	62 min	SSW 14 G 27	10.00 mi	Overcast	43°F	27°F	53%	1021.9 hPa

Link to 5 minute data for KPWK

Wind History from PWK (wind in knots)

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Tide / Current Tables for

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Tide / Current Tables for

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Weather Map

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GEOS Local Image of Midwest    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East

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Wind Forecast for Chicago, IL (14,3,4,5)

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Ground Weather Radar Station Chicago, IL

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