Marine Weather and Tide Forecast for Fox Lake, IL

UPDATE
Issued at 944 AM CDT Sun Mar 15 2026

We have opted to upgrade the Winter Storm Watch across our northwest to a Winter Storm Warning from 7 pm this evening through 1 pm Monday. We strongly considered a Blizzard Warning, but have opted to hold off on that at this time, though cannot rule out the need to upgrade as the event unfolds this evening.
Either way the combination of falling and accumulating snow with widespread blowing snow and gusty northwest winds (up to 50 mph) will make for near blizzard conditions at times tonight into Monday morning across northwestern IL. Total snowfall amounts in the warned area are expected to be in the 3 to 6 inch range.

In addition to the warning, we have also opted to issue a Winter Weather Advisory from 10 pm tonight through 1 pm Monday for areas east-southeast of the Winter Storm Warning. This basically includes areas nearly as far southeast as the I-55 corridor. Snowfall amounts in this region are expected to be lighter, generally in the 1 to 3 inch range. However, the combination of the snow and blowing snow will also make for hazardous conditions outside of the Warning area Monday morning.

KJB

DISCUSSION
Issued at 311 AM CDT Sun Mar 15 2026

Recent surface observations, regional radar data, and GOES-19 water vapor imagery depict the center of a developing low pressure system in central Kansas with expansive radar returns extending northeastward into the Midwest within a tightening low-level baroclinic zone. The expectation is for the surface low to lift northeastward over Kansas City, Missouri this morning, over Davenport, Iowa this afternoon, and over southern Lake Michigan/Lower Michigan this evening into tomorrow. Such a path will squash all four seasons in one day in our local area, with hazards ranging morning thunderstorms, strong to locally damaging non- thunderstorm winds from mid-morning through the afternoon, a threat for damaging-wind producing band of showers and storms this evening, and wind-whipped snow overnight and tomorrow, and wind chills falling below zero Monday night. Good grief!

High Winds Today:

Per RAP mesoanalysis data and regional ASOS data, surface pressures across the Great Lakes are already falling at a rate of 1 to 2 mb/hr in advance of the surface low well to our southwest. A consensus of deterministic model output suggests that surface pressure falls will intensify after daybreak, reaching peak rates on the order of 4mb/hr, 8mb/3hr, and 15mb/6hr centered in Lower Michigan by late morning. Such intense pressure falls will demand a similarly intense low-level mass response, with 925 to 850mb flow progged to increase to 50 to 60 kt, respectively, across eastern Illinois and northwestern Indiana by mid-morning. Even with an increasingly saturated strong low-level inversion beneath a northeastward- advecting EML plume over our area, forecast mixing profiles from the HRRR/RAP/GFS ubiquitously depict the boundary layer tapping into the intense low-level flow primarily along and east of Interstate 57. Indeed, explicit model wind gust output from the HRRR/RAP exceeds 55 mph across far eastern Illinois and northwestern Indiana today, with ensemble means not far behind.
As a result, felt there is justification to issue a High Wind Warning for Ford, Iroquois, and Kankakee counties in Illinois and Lake, Porter, Newton, Jasper, and Benton counties in northwestern Indiana with the expectation for southerly wind gusts of 55 to 60 mph. Gusts should begin abruptly between 9-11 AM and continue through the afternoon and evening hours.

Meanwhile, for locations northwest of the new High Wind Warning area, the initial onset of strong winds will be offset by an initial batch of showers and thunderstorms this morning (more on this in the next section below). With that said, the expectation remains for surface gusts to rapidly increase this afternoon behind the morning convection, albeit to a slightly lower degree than points further east (where low-level wind fields will be stronger). So, will go ahead and expand the Wind Advisory to now include LaSalle, Kendall, Kane, DuPage, Cook, Lake, Livingston, Grundy, and Will counties in Illinois with the expectation for frequent southerly wind gusts of 45 to 50 mph mainly this afternoon.

Thunderstorm / Severe Weather Threat Today:

Outside the strong synoptic winds, being in the warm sector of deepening cyclones this time of year often brings consequences in the form of severe thunderstorms. The first opportunities for thunderstorms today will be between 8 AM and 12 PM primarily across Illinois as an apparent large-scale mesoscale gravity wave activates the EML plume into a northeastward-band of convection. While steep mid-level lapse rates (already sampled near 8.5 K/km per the 00Z ILX RAOB) intersecting the minus 10 to minus 30 layer will promote the development of hail, convective-layer shear looks relatively meager during the morning (only about 20 to 25 kt). Accordingly, the main threats with any morning convection should be downpours, lightning strikes, and spits of pea to dime size hail.

This evening, the surface low will move across far northern Illinois and drive a cold front through the area. Ahead of the cold front, the aforementioned strong southerly winds will rapidly advect a plume of lower 50-degree dew points currently across Arkansas and Oklahoma northeastward into Illinois and northwestern Indiana, leading to the generation of very modest but sufficient low-centric MLCAPE on the order of 250-400 J/kt.
With low-level strong convergence along and DCVA moving atop the cold front, the expectation remains for a narrow (10 to 15-mile wide) band of shallow (maybe 10-15kft deep) convection to develop along the front and sweep across our area.

While the convective band may not look like much on radar once it develops, it will have access to the aforementioned strong low-level flow (50 to 60kt from 925 to 850mb, some 0-3km shear approaching 50kt). As a result, the band will be capable of producing damaging winds of 60 to 75 mph as it races across our area. If instability were to verify on the upper-end of guidance (some CAMs depict 150 J/kg of 0-3km CAPE), would have to watch for any line breaks or kinks in the convective band or just more discrete convective cells in general to support tornadic mesovortices capable of EF-0 to EF-1 caliber damage. Confidence in the threat for tornadoes in these kinds of set-ups is relatively low and often comes down to surface conditions right as the line of storms is developing, so we should have a better idea of what we're dealing with later this afternoon. For what it is worth, the November 5, 2022 severe weather event appears to be a fair analog in which a narrow band of showers produced swaths of 60 to 75 mph winds and an EF-0 tornado across northern Illinois. Albeit, the threat area today is areawide and later in the day (primarily between 4 and 9 PM), and not just confined to Illinois.

Finally, while perhaps not the most likely our or current expected evolution of convection this evening, would be remiss to ignore the possibility for localized flooding owing to intense cool-season-like synoptic-scale forcing overlapping warm-season like PWATS over 1". Should a southwest-to-northeast oriented band of convection manage to develop this afternoon/evening (perhaps along a pseudo warm- frontal boundary somewhere between I-88 and southern Wisconsin), the aforementioned strong forcing and high moisture values would support localized swaths of rainfall totals in the 1 to 3 inches. Interestingly, successive runes of the deterministic ECMWF and HRDPS have depicted such a threat with convection this afternoon and evening, though other CAM guidance such as the HRRR depict far less impressive QPF footprints. Regardless, should such a swath of rain manage to materialize today, instances of flooding in poor drainage or urban areas cannot be ruled out.

Winter Weather Threat Tonight/Early Monday:

As the surface low lifts into Michigan this evening, the dry slot of the cyclone will race into northern Illinois and northwestern Indiana leading to a transition of anafrontal showers to mist and drizzle. With time through the overnight hours, increasing upper- level diffluence in the right entrance region of 125kt 500mb jet max racing into the Great Lakes will support the development of an expansive "comma head" deformation band of snow along the departing system, more or less centered along the Mississippi River and into Wisconsin. As this occurs, rapid pressure rises in the wake of the surface low (pushing 12mb/6hr) will lead to yet another period of strong winds gusting 45 to 55 mph, this time out of the northwest. The overlap of the strong northwesterly winds and falling snow will lead to an area of hazardous to downright travel conditions with localized blizzard conditions.

Curiously, we continue to see quite a bit of variance in the size, location, and ultimate strength of the deformation band of snow, seemingly tied to subtle differences in the evolution of the surface low. Global guidance, which is probably more representative of synoptic forcing, depicts the deformation shield being quite expansive and encompassing much of northwestern Illinois. In such scenarios, increasingly fluffy and blow-able snow would lead to blizzard-like conditions northwest of a line from Mendota to Crystal Lake with total snow accumulations north of 6 inches. Meanwhile, high-res CAM guidance which is more representative of convective processes, is far less expansive and generally weaker delivering little to no snow accumulations to our area (but still with strong winds).
Taken together, the combined HRRR/LREF 10th to 90th percentile snowfall at Rockford remains unusually large, spanning 1 to 8 inches.

All things considered, we simply do not have the confidence to hoist/change winter headlines right right now. So, will have to take the unsavory route of a low-lead time situation by giving the day shift the final say after seeing a couple more suite of model guidance (06, 12Z) to build confidence on the strength and placement of the deformation band. Sometimes, it's easier to decidedly be on the cold side instead of in the path of the center of the low!

One last thing... The propagation of the aforementioned 125mb 500mb jet away from the base of the trailing upper-level trough this evening will cause the upper-level flow to become very unbalanced and supportive of the generation of mesoscale gravity waves through the spontaneous balance adjustment process.
Interestingly, several CAMs, including the HRRR and RRFS, depict two distinct mesoscale gravity waves propagating northeastward within the deformation band across eastern Iowa, northwestern Illinois, and southern Wisconsin this evening. Should the gravity waves occur, the deformation shield may break up into "ribbons", with bands of locally higher precipitation rates intertwined with bands of no precipitation. Lift at the leading edge of each gravity wave may support the generation of a lightning strike and hail within the bands of enhanced precipitation rates as well, given modestly steep lapse rates intersecting a region of temperatures colder than minus 20C above 600mb. And, the passage of mesoscale gravity waves may lead to an enhancement of surface winds and oscillatory changes in wind direction as well, as the local pressure gradient similarly oscillates with the passage of each wave. The HRRR In particular hints at the potential for gravity-wave enhanced winds to poke up toward 60 mph out of the northeast in the deformation shield tonight. So, this will be something to monitor this evening.

Monday and Monday Night:

Behind the departing low pressure system, unseasonably cold air will rush into the area on Monday with 850mb temperatures poised to fall toward -15C. With northwesterly winds blowing 40 to 45 mph, Monday afternoon high temperatures in the lower 20s will feel more like the single digits. Such cold low-level temperatures will also lead to the development of low-level instability by early afternoon, and support the generation of horizontal convective roll-like snow showers from late morning through the afternoon hours. In these kinds of regimes, conditions can vary from perfectly fine to near blizzard-like across short distances around and within the snow showers. So, this time period may require a Winter Weather Advisory for parts or all of the area.

Monday night, 850mb temperatures will tumble toward -20C leading to a downright chilly night. Overnight lows will range from the mid single-digits northwest to the lower teens southeast, with wind chills falling to the minus 5 to minus 10 range. While uncomfortably chilly, record lows at Chicago and Rockford should not be threatened.

Borchardt

Tuesday through Saturday:

The unseasonably cold start to the day on Tuesday will lower the ceiling for the day's high temperatures, with temperatures presently favored to peak only in the 20s. With expansive surface high pressure shuffling its way eastward across the region, no precipitation is expected during the daytime hours.

A fast-moving clipper-type shortwave diving southeastward out of Alberta will arrive at our doorstep Tuesday night. Nearly all members of the 00Z EPS and GEFS output a modest amount of QPF across our forecast area Tuesday night into Wednesday morning, which would translate to measurable snowfall with air temperatures not expected to rise above freezing until sometime during the mid to late morning on Wednesday. Some ensemble spread remains with the strength of the inbound wave and how much moisture it will have to work with, but overall, this doesn't have the look of a blockbuster snowfall event.

A strong upper-level ridge initially centered off the California coast will reposition itself eastward over the Desert Southwest for the latter half of the week. This will kick off a warming trend here locally through the end of the workweek as the associated thermal ridge expands eastward, with highs in the 50s and 60s expected to make a return.

The jet stream draped around the ridge's northern periphery will also get nudged eastward, which will steer any subsequent clipper waves/systems emanating out of Canada more to our east.
That said, one additional clipper shortwave may still get close enough to our area Wednesday night into Thursday for another round of precipitation to occur here. This outcome is reflected only in a minority of Grand Ensemble members at this time, so made no changes to the dry NBM forecast at this juncture.

Ogorek

AVIATION /18Z TAFS THROUGH 00Z TUESDAY/
Issued at 1238 PM CDT Sun Mar 15 2026

Key Aviation Messages for the current TAF period:

- Another round of showers and thunderstorms this afternoon

- Strong southwest wind gusts in excess of 30 knots, locally up to 40 knots

- Winds will switch to the northwest behind a cold front tonight, but remain gusty through Monday morning

- Precipitation will switch from rain to snow behind the cold front, with a short window of wintry mix (rain/snow/sleet)
during the transition

- The combination of snow and strong wind gusts will result in reduced visibility Monday morning from blowing snow.

There is a bit of a break in the rain and storms at the moment.
There are a few light echos on radar that will persist through the early afternoon which could lead to a brief shower at any local site. Winds have underperformed thus far, but gusts out of the southwest over 20 knots prevail and are expected to increase this afternoon with prevailing gusts of 30 to 35 knots.
However, the next batch of showers and storms is in eastern Iowa and tracking east. Moderate confidence in the timing of showers and storms in the TAFs, but expected to be east of KGYY after 02Z.

The center of low pressure, and a subsequent cold front, that is driving this afternoon's showers and storms is projected to move over northern Illinois into early evening. Winds are expected to flip to the north-northwest behind the front. Lower confidence on the exact timing of precip changing from rain to snow, but there is a short window (less than two hours) where terminals can expect reduced visibility due to a wintry mix of snow and rain and perhaps some sleet. As temperatures drop well below freezing around and after midnight, precip will transition to all snow through the day on Monday. Terminals can expected lower cigs and vis due to the snowfall. Highest accumulations are expected around KRFD which could be in excess of 4 inches, while the Chicago Metro is expected 1 to 2 inches. However, the bigger impact from this system will be the blowing snow. The northwest wind gusts are expected to remain strong overnight with the strongest gusts expected Monday morning.

Snow showers are expected to remain through Monday morning before gradually tapering off in the early afternoon as the system finally moves east.

DK

LOT WATCHES/WARNINGS/ADVISORIES
IL...Winter Storm Warning from 7 PM this evening to 1 PM CDT Monday for ILZ003-ILZ004-ILZ008-ILZ010.

Winter Weather Advisory from 10 PM this evening to 1 PM CDT Monday for ILZ005-ILZ006-ILZ011-ILZ012-ILZ013-ILZ019- ILZ020-ILZ103.

Wind Advisory until 9 PM CDT this evening for ILZ006-ILZ012- ILZ013-ILZ020-ILZ103-ILZ104.

Wind Advisory until 9 PM CDT this evening for ILZ019-ILZ021- ILZ032-ILZ105-ILZ106-ILZ107-ILZ108.

High Wind Warning until 9 PM CDT this evening for ILZ023- ILZ033-ILZ039.

IN...High Wind Warning until 9 PM CDT /10 PM EDT/ this evening for INZ001-INZ002-INZ010-INZ011-INZ019.

LM...Gale Warning until 10 PM CDT Monday for the IL and IN nearshore waters.