Marine Weather and Tide Forecast for Lincolnwood, IL

DISCUSSION
Issued at 258 AM CDT Fri May 23 2025

Through Saturday:

Early morning upper air analysis illustrates ridging across the southern and central Plains and a prominent longwave trough encompassing the northeastern quadrant of the CONUS with a northwesterly jet stream sandwiched in between these two synoptic-scale features. A shortwave trough emanating out of the northern Plains will zip through the northwest flow along the associated baroclinic zone today, with an uptick in upper- level cloud cover expected to be the most apparent sign heralding its arrival. Meanwhile, at the surface, winds will largely remain out of the northwest today, though closer to Lake Michigan, a lake breeze will push inland this afternoon and shift winds to a direction between northerly (in northwestern Indiana) and easterly (in northeastern Illinois). These wind directions will once again help hold today's high temperatures below the climatological normals for this time of year, though away from the lakeshore, today's highs should end up much closer to these normals compared to yesterday with inland afternoon temperature readings likely to range from the low 60s to around 70. Closer to the lake, it will be another day where temperatures fail to make it out of the 50s.

There are still some questions regarding how much boundary layer mixing will occur during the daytime and how much that will end up affecting surface dew points. This is relevant for today's forecast as if dew points aren't scoured out as aggressively as the HRRR, RAP, and HRW-ARW are suggesting, then a sliver of meager surface-based instability may materialize in the southern half of our forecast area this afternoon right as the aforementioned shortwave is knocking on our doorstep. The 00Z runs of the CAMs that don't appreciably mix out the mid 40s surface dew points actually pop some showers and output light QPF across this narrow, modestly unstable corridor south of I-80. However, a close inspection of forecast soundings in these models suggests that this output is likely overdone as cumulus growth will be inhibited by a temperature inversion near 750-700 mb. When coupled with dry low-level air, this will likely render cloud depths that should be insufficient to support much of any appreciable precipitation. For this reason, kept our going forecast dry across the entirety of our CWA, but opted to add in a strip of "silent" PoPs up to 10% south of I-80 where some blips of light rain could not be ruled out wherever confluence in the surface wind field ends up promoting clumpier, deeper cumulus growth.

Late this afternoon into tonight, the eastern fringes of a broader shield of precipitation associated with greater large- scale forcing to our west should cross the Mississippi River into Illinois. A minority of the latest model guidance suggests that some of this precipitation could graze our southwestern counties, but the more likely scenario is that this rain will remain bottled up well to our west and south, so have again maintained a dry forecast for tonight. Otherwise, if the associated cloud cover doesn't end up being too much of a hindrance to radiational cooling efforts, then -- much like this morning -- a couple of spots in northern Illinois and northwest Indiana could see low temperatures fall just below 40 degrees, while the rest of the area sees low temperatures that are solidly in the 40s once again.

The influence of surface high pressure in the region will be felt once again on Saturday, which should feature similar conditions to today. Another lake breeze is expected to develop, keeping locations near Lake Michigan in the 50s, while inland locations climb into the 60s once again. Dry conditions will also once again be favored across our forecast area.

Ogorek

Saturday night through Thursday:

Next week, a strong upper-level trough stalled off the western coast of British Columbia will lead to persistent mid-level warm-air advection across western Canada. As a result, anomalous upper-level ridging (500 mb heights >2 sigma above normal over Hudson Bay) is expected to persist across central Canada. With residual upper-level troughing trapped across the northern United States to the south of the ridging to the north (and yet another reinforcing Pacific trough due to dig into the northwestern US by the middle of the week), the upper-level pattern next week across North America will be more or less locked and blocked in place.

In terms consequences of the blocky pattern on the weather in our local area, ensemble median heights and 850mb temperatures from the EPS and GEFS next week resemble either a flat line or modest upward curve from Sunday onward. Accordingly, there is medium to high confidence that the general trend in temperatures next week should be steady to eventually upward. Highs advertised by the NBM in the upper 60s through the middle of the week to the 70s by the end of the week hence appear appropriate. With a surface high pressure system trapped across southern Canada next week, persistent northeasterly (onshore) flow across the Great Lakes will continue to stunt high temperatures some 10 to 15 decrees cooler along the Lake Michigan shore compared to locations further inland.

With the northeasterly surface flow and trapped upper-level flow also blocking meaning moisture from the Gulf region streaming northward toward the Great Lakes, the pattern next week will not be supportive of widespread or soaking rainfall.
The "best" opportunity for rain will be during the middle of the week (Tuesday/Wednesday timeframe) as the upper-level trough currently along the California coast tries to sneak east- northeastward and merge with the aggregate troughing trapped across the northern United States. Given the trough will be disconnected from the mean flow well to the north, exactly how the merging process will take place is an item of lower than average confidence (ensemble IQR heights push 5 to 10 dm by the middle of next week). All things considered, low-end chance (20 to 40%) PoPs advertised by the NBM in the Tuesday/Wednesday timeframe appears reasonable for now.

Looking well ahead, ensemble model guidance suggests the blocky pattern may struggle to decompose until the first week of June.
By that point, ensemble meteograms advertise mean highs returning toward or just above average values for the time of year, accompanied by a return of regular chances for showers and thunderstorms. Time will tell if such a signal will persist.

Borchardt

AVIATION /06Z TAFS THROUGH 12Z SATURDAY/
Issued at 1158 PM CDT Thu May 22 2025

There are no aviation concerns through the TAF period.

Strong surface decoupling will continue to support nearly calm winds through sunrise. A few mid clouds (based 7kft and 10kft)
will pass through from time to time overnight, as well.

Winds should become north to northwesterly at less than 10 kt as a FEW to SCT cumulus deck rooted at 5kft sprouts by mid- morning. A lake breeze is expected to move inland during the afternoon hours. Will maintain the inherited timing of the northeasterly wind shift at GYY around 18Z, MDW at around 19Z, and ORD at around 20Z. Winds will again become calm tonight thanks to efficient surface decoupling. A few to scattered high clouds (based between 20 and 25kft) will stream overhead tonight.

Borchardt

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