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 291103 AFDLOT

Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 503 AM CST Wed Jan 29 2020

SHORT TERM. 322 AM CST

Through Saturday .

Persistence appears to be the way to go with the forecast. Broad upper trough over the region with subtle/weak shortwave troughs rippling through the area at somewhat regular interval. Each trough looks to be lacking moisture and likely only providing some modest ascent. Our CWA looks to be close to smack dab in the middle of a persistent stratus deck that looks like it covers at least 25% of the Lower 48. No indication that anything will result in clearing out of this stratus through Saturday with minimal subsidence and negligible advection.

Will need to watch for potential flurries or very light snow with each passing weak shortwave trough. One such wave will move across the area later today with forecast soundings showing the majority of the ascent aloft, however, with deepening mid-upper level cloud cover likely producing virga that could go on to seed the stratus deck and produce light snow/flurries. Given that the interceding dry layer the virga needs to survive to "feed" the stratus looks to be sizable, I'm not expecting more than a trace to perhaps a tenth of two of an inch on the high side of snow this afternoon and evening. For the most part, the lower CIGS and higher boundary layer moisture conducive for meaningful FZDZ has remained west of our CWA. We'll need to keep an eye on the FZDZ potential with this wave and subsequent waves through Saturday morning, but at this point the potential is too low to add to the forecast.

One effect of the stratus has been to keep low temps fairly mild and consistently warmer than most, if not all, available guidance. Have adjusted forecast lows in the forecast significantly higher than the NBM through Friday night with recent verification stats showing the NBM with one of the more sizable cold biases for nighttime lows this past week.

- Izzi

LONG TERM. 322 AM CST

Saturday night through Tuesday .

Big pattern changed still slated to take place in the longer term period. First, a transition to more of a zonal flow then some low amplitude ridging over the central & eastern U.S. Low/mid level flow will turn westerly Saturday night and should finally push this stratus deck out of the area and set the stage for sunshine Sunday. Source region for our low level air mass Sunday is from the down sloped Chinook warmed areas of the central Plains. At this point, the biggest limiting factor temps will be the ambient snow cover. Progged 925mb temps support highs at or above 50 in areas with little or no snow cover, though one potential complicating factor for Chicago is that west winds will be blowing off a deeper snow pack over north central IL. NBM has trended warmer with high temps and latest model guidance would support highs even warmer in areas of no or minimal snow pack, but with the NBM trending up gradually, didn't make any big changes to forecast high temps. Again, if guidance remains consistent, later forecast should have highs in the 50s over the snow-free portions of the CWA.

Low confidence forecast beyond Sunday as several players look to get involved, including a northern stream trough passing by the upper Great Lakes, a digging western U.S. long wave trough, and potential lead shortwave trough ejecting out from the digging western trough. Not surprising given so many moving, but there are some significant differences among the various medium range models. At this distance, it looks like it will be unseasonably mild initially before a strong cold front slips south and knocks temps back down to near seasonal norms. Timing of the front will play a big role in high temps Monday, slower arrival and another day of 40s over snow cover and 50s elsewhere would be likely, with an earlier arrival meaning highs in the 30s. Precipitation chances look to increase later Monday into Tuesday, though timing and precip type are still big question marks at this point. With cold air probably infiltrating the area, any system ejecting from the western trough will bear watching.

- Izzi

AVIATION. For the 12Z TAFs .

Overall it is looking like a fairly quiet weather day across the terminals. Expect MVFR CIGS, at or above 2,000 feet, to continue across the area through most of the taf period. We will also likely see some intermittent flurries through the day today, though no real impacts are expected. Otherwise, winds will remain light and somewhat variable through the period.

KJB

LOT WATCHES/WARNINGS/ADVISORIES. IL . None. IN . None. LM . None.

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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	38 min	NNE 12 G 14	31°F				27°F
CNII2	13 mi	28 min	N 6 G 8	30°F				25°F
CMTI2 - 9087044 - Calumet, IL	22 mi	58 min	NNE 5.1 G 8.9	32°F			1020.6 hPa	26°F
KNSW3 - Kenosha, WI	39 mi	28 min	N 8 G 9.9	28°F			1021.7 hPa (+0.7)
MCYI3 - Michigan City, IN	46 mi	38 min	S 1.9 G 2.9	31°F				25°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	36 min	N 3	10.00 mi	Overcast	30°F	21°F	72%	1022.8 hPa
Chicago, Chicago-O'Hare International Airport, IL	12 mi	37 min	N 4	10.00 mi	Overcast	31°F	23°F	72%	1021.9 hPa
Chicago, Chicago Midway Airport, IL	17 mi	35 min	N 0	9.00 mi	Light Snow	31°F	26°F	82%	1022.6 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 (7,2,3,4)

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Ground Weather Radar Station Chicago, IL

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