Marine Weather and Tides
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.
|Sunrise 5:33AM||Sunset 8:21PM||Friday July 21, 2017 5:46 PM CDT (22:46 UTC)||Moonrise 3:43AM||Moonset 6:45PM||Illumination 3%|
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|LMZ741 Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 506 Pm Cdt Fri Jul 21 2017 |
.severe Thunderstorm watch 429 in effect until midnight cdt tonight...
Tonight..Southeast winds 10 to 15 kt becoming south 10 to 20 kt after midnight, then becoming 10 to 15 kt late. Chance of showers and Thunderstorms, then showers and Thunderstorms. Waves 1 ft or less building to 1 to 3 ft late.
Saturday..Southwest winds 10 to 15 kt becoming northeast in the afternoon. Chance of showers and Thunderstorms. Waves 1 to 3 ft.
Saturday night..North winds 5 to 10 kt becoming northwest after midnight. Mostly cloudy. Waves 1 to 3 ft.
Sunday..West winds 10 to 15 kt. Slight chance of showers and Thunderstorms in the afternoon. Waves 1 to 3 ft.
|LMZ741 Expires:201707220315;;614799 FZUS53 KLOT 212206 NSHLOT NEARSHORE MARINE FORECAST National Weather Service Chicago/Romeoville IL 506 PM CDT Fri Jul 21 2017 For waters within five nautical miles of shore on Lake Michigan Waves are provided as a range of significant wave heights, which is the average of the highest 1/3 of the waves, along with the average height of the highest 10 percent of the waves which will occasionally be encountered. LMZ740>742-220315-|
7 Day Forecast for Marine Location Near Evanston, ILHourly EDIT Help
Area Discussion for - Chicago, IL  (on/off)  Help NOTE: mouseover dotted underlined text for definition
|Fxus63 klot 212131|
area forecast discussion
national weather service chicago romeoville, il
431 pm cdt Fri jul 21 2017
426 pm cdt
severe thunderstorm threat increasing across northern illinois
late this afternoon within a strongly unstable and moderately
sheared airmass. Couple areas of concern noted per regional obs
and satellite imagery. First, an outflow boundary is draped from
the northern suburbs of chicago wsw to near the quad cities this
afternoon. Satellite imagery reveals changes in the
characteristics of the cloud cover along the boundary suggesting
weakening convective inhibition and would expect thunderstorm
coverage to further increase over the next hour or two along this
boundary. Moderately strong deep layer bulk shear would support
supercell development, and low LCL heights and increased SRH along
the aforementioned boundary suggests there is some threat for
tornadoes this afternoon evening.
Second area of concern is a warm frontal boundary draped from near
the quad cities southeast through near pontiac to danville.
Cumulus not really well defined along this boundary at the moment
but there are some thunderstorms developing just south within the
warm sector. If further development occurs along the front,
bunkers right moving supercell vectors oriented parallel to the
boundary suggest that storms could become latched onto the
boundary which would also be an area of concern for
Beyond the next couple hours, strengthening low level jet this
evening will result in renewed thunderstorm development to our
west with training thunderstorms producing heavy rain and a
heightened flooding concern, especially given saturated soils in
255 pm cdt
main forecast concerns challenges continue to be tied to
additional thunderstorms which are likely today into tonight, with
severe and flash flooding threat likely this evening and
Feeling fairly confident this afternoon that much of northern
illinois and northwest indiana will be right in the center of much
of the thunderstorm activity during this period. Despite earlier
guidance and even some of the global models showing a more
northerly track with any convection today tonight, persistence
seemed to be the best route to take with the forecast. Once again,
no real big change to the large scale pattern, along with
moisture instability axis still focused right into the cwa. With
this in mind, a more southerly track with any upstream development
appears to be the most likely scenario, and have updated the
forecast to reflect this current thought.
Latest radar imagery showing thunderstorms continuing to slowly
propagate through northeast iowa and southwest wisconsin. General
motion with the current storms just northwest of rockford has been
mainly to the east. Although this will likely continue east, am
monitoring for possible development along its southern edge that
could clip more of far northern illinois this afternoon. This
possibility seems reasonable, as instability continues to rebound
further north in the high dewpoint air. If this occurs, at this
time, it should stay tied to areas near the il wi border. However,
will continue to monitor for a possible continued southerly
development of this leading edge, into areas along near the i-88
corridor in northeast illinois this afternoon. A strong severe
threat would be likely with these storms, along with heavy
Expect current thunderstorms across ia to further develop quickly
over the next couple of hours, in around surface trough and
synoptic boundary. Once again, expect a east southeast movement
through the afternoon and early evening right into northern
illinois and northwest indiana. As these storms move east this
afternoon intensification likely as they encounter a very moist
and unstable air mass in place over eastern iowa, northern
illinois, and northwest indiana. Development likely into forward
propagating line of storms appears likely with a damaging wind
threat appearing highly probable by early this evening across
north central illinois. No change in the environment throughout
the cwa, so feel fairly confident of this line of storms to
continue east southeast through the remaining areas in northern
illinois and northwest indiana through mid to late this evening,
with a damaging wind threat also continuing. At this time, all
locations in northern illinois and northwest indiana are in the
path of these storms. Given the environment instability, can't
rule out a high end wind threat of 60- 80 mph with the strongest
storms. Although high winds will be the main threat, a tornado
threat will remain. This is especially the case as a synoptic
boundary and outflow boundary will be situated across the region,
which could act to support a locally higher chance of a tornado.
Torrential rainfall will be possible with any storm and with the
initial storms this evening, expect more of a progressive movement
with the storms. This could limit the initial flash flood risk,
but don't want to downplay this too much as a quick 1 to 3 inches
will be very possible this evening. This would fall within the
flash flood watch area, and locations that have already saturated
conditions, with flash flooding still a definite possibility.
Additional thunderstorms appearing likely overnight, with
increasing LLJ and boundaries in place. Focus continues to be in
the watch area in northern illinois, north of i-80. Additional
torrential rainfall will be possible during this time, with a
pattern of training storms a definite possibility. This will keep|
concerns high for flash flooding overnight. No change to the
current watch, but will monitor the possibility of areas just to
the south and east of the watch to get into the location of
402 am cdt
Saturday through Thursday...
Saturday afternoon heat and humidity will again push apparent
temperatures toward or over heat advisory criteria with the support
of southwest flow ahead of an approaching frontal zone. Model qpf
fields and mslp trends reflect disagreement in the timing and low
level forcing related to the passage of the front, perhaps due in
part to the potential stabilizing effects from widespread convective
activity expected tonight and in the predawn and morning hours on
Saturday. Still feel that, at the least, isolated to scattered
activity is possible areawide for the Saturday afternoon period,
but toward evening and overnight the focus shifts mostly south of
the chicago metro area.
A considerable pattern change is then in store, with Sunday looking
like a transition day toward drier weather with cooler temperatures
and lower dewpoints as an upper trough digs over the area and a
broad surface ridge approaches the great lakes from the northwest.
Sunday appears to be just a bit cooler and drier than Saturday,
but the change will be more evident on Monday and Tuesday when
some locations do not escape the 70s. By mid to late week the
ridge likely will move far enough east to allow more typical
warmth and moisture to start streaming back into the area, but at
this range we do not appear positioned for a late-week repeat of
the recent very warm heat and high humidity.
For the 18z tafs...
primary concerns center around the timing of thunderstorms at the
A few showers may continue eastward this afternoon, but at this
point we do generally feel these will remain in a tempered state
with some capping in pace.
Model spread is still high enough to retain tempered confidence,
likely medium as this point, regarding specific timing on thunder
impacts at the terminals, but confidence has increased regarding an
earlier arrival time for the leading edge of storms this evening and
for additional development overnight.
Expect a leading storm complex to move into area this evening, and
these storms will likely pose a concern for gusty northwest winds.
Concerns then shift to what appears to be a a favorable setup for
backbulding storms during the overnight hours. While this is
expected to happen, whether this is over the terminals or a bit
south is still in the air, but our feeling overnight is that there
will likely be some very heavy rain producing storms. The
boundary does appear to linger over our terminals on a NW to se
axis from rfd through chicago, so the best course of action is
continue the thunder mention into the overnight hours across the
terminals. Confidence on how quickly storms shift south of the
terminals is also low, and tweaks may be needed for this
Confidence is pretty high that after 12z things will shift south of
the terminals and the impacts will dwindle. At this point confidence
on wind direction diminishes, so future adjustments may be
needed. Additional development is possible tomorrow afternoon,
but the bulk of guidance is drier than previous forecast will
likely hold dry.
1251 pm cdt
strong to severe thunderstorms are expected over the southern
third of the lake this evening, with gusts in excess of 30 kt
certainly plausible, along with heavy rain.
Otherwise, thermal circulations exist this afternoon across
nearshore areas with a broad southeast wind regime in place. A low
pressure trough will cross the lake tonight with the main low
center not expected to cross the lake until later Saturday which
will maintain the east wind component until the low moves south of
the lake Saturday night.
Once the associated low shifts east, the flow around to the north
where it will remain and gradually increase into early next week, to
the point that small craft advisories may be needed along the
southern shores on Monday with a full northerly fetch wind. The
gradient then appears to relax again on Tuesday through mid to late
Lot watches warnings advisories
Il... Flash flood watch... Ilz003-ilz004-ilz005-ilz006-ilz008-ilz010-
until 9 am Saturday.
Visit us at http: weather.Gov chicago (all lowercase)
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Weather Reporting StationsEDIT (on/off)  Help NOTE: Click on distance to see the station location on a map
|Stations||Dist||Age||Wind||Air Temp||Water Temp||Waves||Pressure||DewPt|
|FSTI2||4 mi||106 min||Calm||76°F|
|45174||7 mi||26 min||ENE 5.8 G 7.8||74°F||73°F||1 ft||73°F|
|OKSI2||9 mi||106 min||S 1.9||76°F|
|CHII2 - Chicago, IL||10 mi||26 min||NE 7 G 8||77°F||72°F|
|45177||10 mi||166 min||75°F|
|CNII2||13 mi||16 min||76°F|
|JAKI2||18 mi||106 min||SSW 1||76°F|
|CMTI2 - 9087044 - Calumet, IL||22 mi||46 min||ESE 4.1 G 8||80°F||1013.2 hPa (-1.3)||72°F|
|WHRI2 - Waukegan Harbor, IL||24 mi||66 min||E 2.9 G 5.1||74°F|
|BHRI3 - Burns Harbor, IN||39 mi||43 min||S 5.1 G 13||85°F||1013.9 hPa|
|KNSW3 - Kenosha, WI||39 mi||46 min||E 9.9 G 13||73°F||1013.2 hPa (-1.7)|
|45170||43 mi||26 min||ENE 5.8 G 5.8||78°F||77°F||74°F|
|MCYI3 - Michigan City, IN||46 mi||26 min||W 2.9 G 5.1||82°F||71°F|
Wind History for Calumet Harbor, IL(wind in knots) EDIT (on/off)  Help
Airport ReportsEDIT (on/off)  Help Click EDIT to display multiple airports
|Chicago / Wheeling, Pal-Waukee Airport, IL||12 mi||54 min||N 0||6.00 mi||Thunderstorm Light Rain Fog/Mist||77°F||75°F||94%||1014 hPa|
|Chicago, Chicago-O'Hare International Airport, IL||12 mi||55 min||Var 4||1.75 mi||Thunderstorm Heavy Rain Fog/Mist||82°F||72°F||72%||1013.2 hPa|
|Chicago, Chicago Midway Airport, IL||17 mi||53 min||S 9||10.00 mi||Mostly Cloudy||87°F||70°F||57%||1011.8 hPa|
Wind History from PWK (wind in knots)
|1 day ago||E||NE||NE||NW|
|2 days ago||E||E||SE||Calm||SW||SW||SW||W||W||W||SW||SW||W||W||NW||NW||N||NE||NE||E||NE||NE |
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Weather Map and Satellite Images(on/off)  Help
|Weather Map ||IR Satellite Image from GEOS|
GOES Local Image of Midwest EDIT
Wind Forecast for Chicago, IL (18,4,5,8)(on/off)  Help
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