Saturday, May27, 2017 L-36.com


Marine Weather and Tides
Joliet, IL

Version 3.4
What's New / NOTES
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 5:21AMSunset 8:18PM Saturday May 27, 2017 6:50 AM CDT (11:50 UTC) Moonrise 7:23AMMoonset 10:23PM Illumination 4% Phase: Waxing Crescent; Moon at 2 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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LMZ742 Winthrop Harbor To Wilmette Harbor- Wilmette Harbor To Northerly Island- Northerly Island To Calumet Harbor- 345 Am Cdt Sat May 27 2017
Today..Northeast winds 5 to 10 kt becoming east in the afternoon. Mostly cloudy with patchy fog in the morning then clearing. Waves around 1 ft.
Tonight..East winds 10 to 15 kt. Rain showers likely and a chance of Thunderstorms after midnight. Waves 1 to 2 ft.
Sunday..East winds 5 to 10 kt becoming northwest 10 to 15 kt in the afternoon. Chance of showers and Thunderstorms. Waves around 1 ft.
Sunday night..West winds 10 to 15 kt. Partly cloudy. Waves around 1 ft.
LMZ742 Expires:201705271515;;276272 FZUS53 KLOT 270845 NSHLOT NEARSHORE MARINE FORECAST NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 345 AM CDT SAT MAY 27 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>742-271515-

7 Day Forecast for Marine Location Near Joliet, IL
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location: 41.52, -88.16     debug


Area Discussion for - Chicago, IL
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Fxus63 klot 270830
afdlot
area forecast discussion
national weather service chicago romeoville, il
330 am cdt Sat may 27 2017

Short term Through tonight...

329 am cdt
near term concerns center around cool and moist conditions with
pockets of clouds and even some fog and then switch back to
shower and thunderstorm chances overnight into Sunday.

A relatively moist air mass was left in the wake of yesterday's
rainfall. With high pressure moving in briefly behind this system,
clouds have been slowly clearing, but given the low dewpoint
depressions, even lower clouds have and should continue to fill in
for many locations that lose the initial cloud deck given the
lighter winds. In the cloud breaks fog has been occasionally near
dense in spots, but generally after period of visibility
reductions the light NE wind component congeals this into a low
cloud deck.

Forecast soundings from the rap hrrr depict this moisture to be on
the shallow side and generally consistent with obs, and both
indeed show somewhat fast clearing lifting by mid morning or so.

After the clouds and slow temperature climb, a seasonally mild
airmass aloft should translate to temperatures near or a tad above
normal, with 70s and even some low 80s south. Afternoon clouds
may hamper things a tad from upstream convection, and onshore flow
will keep the lake areas cooler yet again.

Eyes then turn to the endless parade of shower embedded
thunderstorm complexes, the next one across ks ne. While the
precipitation shield is fairly expansive, the better instability
lies along the southern portion of this activity. There is some
disagreement with how the northern portion of this complex will
behave between the hi-resolution cams keeping most of the action
attached to the higher instability axis as the warm front will
remain draped across our southern area. Meanwhile the larger
scale global guidance while consistent in keeping the
thunderstorms largely focused along and south of i-80, is in line
with the large scale pattern of warm moist ascent ahead of the
low and upper height falls suggests at least a period of showers
and some embedded thunder for many areas overnight. Confidence
given these inconsistencies gets lowered some, but the timing of
occurrence would be mostly after midnight with higher confidence.

Increased pwats again suggest brief moderate to heavy rainfall.

There is a marginal risk in our southern areas for severe hazards.

Mainly wind hail given the proximity of the warm front.

Kmd

Long term
307 am cdt
Sunday through Friday...

medium range guidance continues to depict that deep upper
troughing will dominate much of the great lakes and northeast
through most of the period. A series of mid-level disturbances
are indicated from Sunday through about Wednesday night which will
present the potential for primarily diurnally driven shower and
thunderstorms through mid-week, before a weakening upper level
ridge shifts east into the region Thursday Friday. Overall, the
pattern will support slightly lower than average temperatures
heading into the start of june.

Remainder of memorial day holiday weekend...

lingering precipitation weak convection may be ongoing early
Sunday morning, especially across the south southeastern parts of
the CWA in association with a low-amplitude short wave and area of
surface low pressure which develops into the area overnight.

Coverage and intensity should be on the decrease as this wave
moves out of the area during the morning, though a broad area of
height falls and large scale ascent is expected to be developing
in advance of the main upper trough axis which approaches the area
from the west northwest during the day. Forecast soundings depict
fairly benign lapse rates initially during the morning in the
wake of the overnight action, though the combination of diurnal
warming and cooling of mid-levels through ascent associated with
the approaching trough should result in new convective
shower thunderstorm development as we head into the afternoon. The
greatest threat of organized storms should be focused along ahead
of the cold front moving out of the eastern parts of the forecast
area through early afternoon, where stronger instability will
exist. Forecast soundings from the WRF depict MLCAPE values
approaching 1000 j kg in the far southeast during the afternoon,
tapering to 300-500 j kg across north central il with slightly
lower surface dew point temps behind the front. Deep layer bulk
shear values of 50-60 kts also shift across the southeastern cwa
during the afternoon, where SPC has maintained a marginal severe
risk for day 2 Sunday. Best focus for strong severe convection
could end up southeast of the CWA defendant upon effective
convergent zone and outflow boundaries from Saturday night mcs
activity. Guidance generally brings the upper trough axis across
the area by during the evening, which combined with loss of
diurnal instability should allow precip to dissipate after sunset.

Pattern persists Monday, with guidance indicating another short
wave propagating through the west-northwest mid-level flow south
of the upper low north of the lakes. Forecast soundings depict
skinny CAPE profiles of a few hundred j kg developing during the
afternoon, within a fairly deeply mixed boundary layer to 800-750
mb. In addition to likely supporting at least some scattered
afternoon showers and thunderstorms, this should produce breezy
westerly surface winds as wind speeds of 30-40 kts are evident at
the top of this mixed layer. Gradient itself is not overly strong,
so have held wind gusts to 30 mph at this time, but this may be
worth monitoring for the potential of more gusty conditions over
the next few model runs. In any case, breezy and mild conditions
are anticipated, with highs both Sunday and Monday expected in the
low-mid 70's and with offshore flow negating lake cooling
especially Monday.

Mid and late next week...

story remains the same as most head back to work Tuesday, though
with slightly warmer mid-level temps limiting the degree of
diurnal instability somewhat. Thus any diurnal showers and
isolated thunderstorms are expected to be limited to northern
portions of the CWA during the afternoon. Breezy westerly surface
winds should still hold off lake breeze development, with highs
from around 70 north to the lower 70's south supported by model
thermal fields.

The upper trough then drifts further east on Wednesday, allowing
surface high pressure to gradually build across the region into
Thursday. Mainly dry weather is anticipated, with weakening west-
northwest winds eventually resulting in the return of lake breeze
cooling for the latter part of the week. Differences develop in
the various guidance by this part of the extended, particularly
with the amplitude of the upper ridge nudging east across the
plains into the mississippi valley. GFS maintains a little sharper
feature, while the ECMWF flattens the ridge considerable and the
gem erodes it and develops a trough by 12z Friday. Thus confidence
in details does lower by the end of the period.

Ratzer

Aviation
For the 06z tafs...

concerns are on existing MVFR and ifr clouds, and then on
ifr lifr clouds and or fog expanding once the lingering clouds
erode. The later periods will then need to address showers and
embedded storms.

An area of lower clouds has begun to erode from the northwest, but
may slow its progression in the overnight hours and likely expand
now that we are in the overnight hours with moist conditions and
light northeast winds under the ridge. In addition where clearing
has occurred, dewpoint depressions are low and not expected to
climb, thus ifr or even lifr clouds will likely return and or low
to very low visibilities. Confidence is not high on how low and
how long conditions stay down but at least occasional reductions
if not longer and the pattern is favorable for low conditions of
some sort for many areas to start the day. What does form may be
initially slow to clear with the light profile, but then just
expect east winds with a lake breeze likely.

An area of showers and thunderstorms across the central and
southern plains will lift northeast tonight. Expect south of the
main terminals where the more active thunderstorms will be given a
significant gradient in instability from south to north, but
expect a period of showers and embedded thunder area wide as the
forcing with the wave is decent. More details with this in the
future tafs and just hinted at for now in ord 30 hr. General timing
is medium-high confidence.

Kmd

Marine
315 am cdt
overall, weak pressure gradient will linger across lake michigan
early in the period, until low pressure lifts out of the plains
and moves across the south end of the lake early Sunday. This low
is expected to deepen as it pulls away to the east-northeast
Sunday night and Monday, and merging with a deeper low which
remains nearly stationary north of the lakes across ontario
through early next week. As this occurs, winds will shift westerly
and increase, with the strongest winds expected Monday and Monday
night. Relatively warm air over the still cool lake waters will
make for stable conditions out away from the shore, and should
limit mixing of stronger winds aloft. Still, westerly wind gusts
of 25-30 kts are possible during the Monday-Tuesday period. The
nearly stationary low will eventually weaken and drift east during
the mid-late week period, with the gradient relaxing again across
lake michigan as a broad area of high pressure spreads southeast
from the northern plains to the midwest.

Ratzer

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 TempWater Temp WavesPressureDewPt
JAKI2 36 mi110 min NNE 9.9 54°F
CMTI2 - 9087044 - Calumet, IL 36 mi50 min N 5.1 G 7 53°F 1011.6 hPa (+1.0)53°F
CNII2 37 mi20 min N 4.1 G 11 54°F
OKSI2 39 mi110 min W 1 54°F
CHII2 - Chicago, IL 41 mi30 min N 6 G 7 53°F 50°F
FSTI2 42 mi110 min N 8.9 52°F
BHRI3 - Burns Harbor, IN 54 mi70 min NNE 7 G 8 53°F 1012.2 hPa

Wind History for Calumet Harbor, IL
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N9
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Joliet Regional Airport, IL1 mi55 minN 04.00 miFog/Mist56°F55°F98%1012.2 hPa
Lewis University Airport, IL7 mi55 minENE 63.00 miFog/Mist55°F54°F100%1011.8 hPa
Morris Muni-James R Washburn Field Airport, IL15 mi55 minN 01.75 miFog/Mist54°F52°F96%1011.8 hPa
Aurora Municipal Airport, IL24 mi58 minENE 55.00 miFog/Mist55°F54°F96%1012.1 hPa

Wind History from JOT (wind in knots)
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Last 24hrCalmSE4S4E9SE10SE9SE11SE7
G16
E6CalmE4E7NW3NE7NE7NE7NE9NE6NE4N3N3N3CalmCalm
1 day agoN8N10NW7N6N6NW7W3NW4NW7W5W6W6CalmCalmCalmCalmE3CalmCalmCalmCalmCalmCalmCalm
2 days agoNE7NE8NE9NE8NE7N8N10N11
G15
N9N8
G14
NE10NE8NE5NE5N4N5N5N6N6N3N4NW5N6N5

Tide / Current Tables for
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Weather Map and Satellite Images
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IR Satellite Image from GEOS
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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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Disclaimer:
The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerious of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.