Monday, May21, 2018 L-36.com


Marine Weather and Tides
Altoona, WI

Version 3.4
What's New / NOTES
5/20/2018 -- NOAA is having problems with the data feed that I use to draw the graphs. They are aware of the issue and working to resolve it. Sometimes changing the location by about a mile will give a correct graph. 3/3/2018 - There is a new GOES Satellite for the east coast that required rewriting that part of the code. Please report any issues.

Sunrise 5:28AMSunset 8:36PM Monday May 21, 2018 10:07 AM CDT (15:07 UTC) Moonrise 11:00AMMoonset 12:42AM Illumination 42% Phase: First Quarter Moon; Moon at 7 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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7 Day Forecast for Marine Location Near Altoona, WI
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location: 44.78, -91.48     debug


Area Discussion for - Twin Cities, MN
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Fxus63 kmpx 211128
afdmpx
area forecast discussion
national weather service twin cities chanhassen mn
628 am cdt Mon may 21 2018

Updated for 12z aviation discussion
Issued at 624 am cdt Mon may 21 2018

Short term (today and tonight)
issued at 310 am cdt Mon may 21 2018
the main challenge in todays forecast is how the interaction of the
upper level disturbance located across south dakota, and
weak theta-e advection across iowa southern minnesota slowly evolve.

Based on current radar and satellite trends, the bulk of the
activity in southwest minnesota will lift northward and slowly
dissipate toward noon, while another area developing across northern
iowa, will spread across south central southeast minnesota through
noon. Between these two systems that are generating scattered shower
activity, will be a lull with only isolated showers possible.

Current pops convey this trend with the highest across
southwest west central minnesota until noon, and another area in
southeast minnesota, and portions of west central wisconsin slowly
increasing in areal coverage through noon. By the afternoon, most of
the activity will slowly begin to dissipate as the main upper level
disturbance moves overhead and east, with any theta-e advection
weakening with time. Temperatures in the 60s will reflect the denser
cloud cover and scattered shower activity. Later tonight, especially
in areas that had more rainfall, fog will likely form as light winds
hold across the area, and skies clear. I wouldn't be surprised to
see areas of dense fog where skies clear quicker in western
minnesota.

Long term (Tuesday through Sunday)
issued at 310 am cdt Mon may 21 2018
there are several chances for thunderstorms starting late Tuesday
and lasting through Friday. At this point it appears that the main
threat for Tuesday Wednesday will be heavy rain, while Thursday
Friday could see more of a severe weather threat. Everything is
very conditional at this point, so expect the forecast to continue
to change over the next few days. Don't want the details
discussion below to give a false sense of certainty.

Tuesday night through Wednesday night - over the next couple of days
an upper level trough will dig over the great basin, and this does
appear to be tied to the polar jet. However, the polar jet will
ridge out across canada, so this upper level wave will slowly fill
and rely on the weak, subtropical jet to advect its positive
vorticity downstream. On Tuesday night a shortwave trough lifts
northeast and induces low level theta_e advection over the upper
midwest.

Increased pops for Tuesday night across southwest minnesota.

Forecast models are in good agreement with precipitation developing
on the leading edge of this warm air advection. Pwat values will be
around 1.5 inches, which is near the 90th percentile for late may.

Meanwhile winds within the entire troposphere are less than 50 kts,
and winds are less than 20 kts from the surface up to 400 mb. Cape
profiles are thin, since at this time there is not an elevated mixed
layer to work with. The end result of this set up should be
overnight convection Tuesday night lingering into Wednesday morning,
and the main threat from these storms is heavy rain. We have been
dry, so at this time the antecedent conditions do not favor flash
flooding, but folks along the minnesota river valley and i-90 could
have a quick 2 to 3 inches or more with any one particular storm.

This convection should weaken and eventually dissipate on Wednesday
as the forcing from the low level jet dissipates.

Wednesday and Wednesday night are of lower concern. There will
probably be some lingering convection across the region, but there
shouldn't be enough CAPE shear for it to be severe. It's difficult
to pin down a persistent area of forcing, so will just continue with
the blended forecast.

Thursday through Friday - the atmosphere changes across the region
on Thursday as an elevated mixed layer seen via the h700-500 lapse
rates lifts up from the southwest. Meanwhile surface temps and
dewpoints increase beneath this eml, so afternoon CAPE values of
3000 to 4000 j kg develop. Based on the forecast soundings, this
instability should remain capped off on Thursday so although there
are pops in the forecast, they likely will not be realized until the
evening when the first of two shortwaves drops down from canada. If
this shortwave trends quicker like the ecmwf, then the convection
could develop sooner.

Deep layer wind shear is still on the low side, but sufficient for
organized convection. The primary threats will be large hail early
on in western minnesota, and then transitioning to a damaging wind
threat Thursday night as the storms move eastward toward wisconsin.

Cips severe analogs have been showing a signal for severe storms
during this time period. Per coordination with spc, there are still
uncertainties in timing, so at this point confidence is not high
enough to highlight a specific area in the day 3 4 outlook.

Friday is also uncertain. There is potential for storms redeveloping
as the second shortwave trough and cold front sweep through the
region. However it is certainly possible that Thursday night's
storms scour out the region of any instability and accelerates the
passage of the cold front.

Looking ahead, it does appear that drier air will move across the
region for the memorial day weekend as high pressure builds off to
the east. Could see some lingering showers on Saturday, but Sunday
and Monday look dry.

Aviation (for the 12z tafs through 12z Tuesday morning)
issued at 624 am cdt Mon may 21 2018
vfr conditions will give way to MVFR conditions and possible ifr
conditions. There is low confidence in the CIGS this morning
because there is a lot of spread among the various forecast
models. With the late may heating, should have cloud bases raise
bit this afternoon before dropping down low again tonight, but
that is not a sure thing. It does however look like ifr lifr
conditions will develop over most of the region tonight.

Kmsp...

challenging forecast with the lower sub-1700 ft ceilings to the
south, andVFR conditions to the north. Msp is in between and they
"should" be MVFR most of the day, with perhaps aVFR break this
afternoon. Later tonight we do expect ceilings to lower below 1700
ft, with some fog possible.

Outlook for kmsp
tue... MVFR CIGS early, thenVFR. Wind SE 5 kts.

Wed...VFR with chc shra tsra late. Wind SE 5-10 kts.

Thu...VFR. Chc -tsra. Wind S 5-10 kts.

Mpx watches warnings advisories
Wi... None.

Mn... None.

Short term... Jlt
long term... Jrb
aviation... Jrb


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chippewa Valley Regional Airport, WI7 mi71 minE 710.00 miOvercast55°F36°F49%1020.2 hPa
Menomonie Municipal Airport-Score Field, WI22 mi32 minE 810.00 miPartly Cloudy59°F37°F46%1020 hPa

Wind History from EAU (wind in knots)
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Last 24hrE7E12
G17
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E9E10E8E8E6E4CalmCalmCalmCalmNE3NE5NE4NE4NE4E9E6E7
1 day agoW7W6W7NW6W6N10N11
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NE8NE7NE7NE8E8
2 days agoSE106
G17
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G23
SE14
G20
SE14SE11SE12
G18
SE5E5SE11SE10SE16SE11S7SE7SE3CalmE4CalmS54

Tide / Current Tables for
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Tide / Current Tables for
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Weather Map and Satellite Images
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GOES Local Image of GreatLakes    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.
target = "new">Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Twin Cities, MN (11,2,3,4)
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Ground Weather Radar Station La Crosse, WI
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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.