Monday, February18, 2019

Marine Weather and Tides
Nunn, CO

Version 3.4
What's New / NOTES
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.

Sunrise 6:49AMSunset 5:38PM Sunday February 17, 2019 10:02 PM MST (05:02 UTC) Moonrise 4:25PMMoonset 6:27AM Illumination 98% Phase: Waxing Gibbous; Moon at 13 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 Nunn, CO
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location: 40.66, -104.88     debug

Area Discussion for - Denver/Boulder, CO
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Fxus65 kbou 180320
area forecast discussion
national weather service denver boulder co
820 pm mst Sun feb 17 2019

Issued at 817 pm mst Sun feb 17 2019
grids have been updated to account for areas of snow developing
east of the foothills. Some bands brought heavier amounts to
locations from golden to evergreen with a narrow area of 3 to 5
inches. This appears to be due to an area of convergence that was
taking place between the foothills and the denver metro area. An
area of warming cloud tops entered from the east was indicated on
satellite imagery. The surface dewpoints are currently in the
single digits so it's mostly just cold and dry. There will be a
chance that the dry air will hold the snow at bay, not allowing
much snow east of dia. Snow accumulations should be highest near
the foothills. Snow will decrease this evening with the incoming
southerly downslope flow.

Short term (this evening through Monday)
issued at 232 pm mst Sun feb 17 2019
a short wave ridge over colorado brought mostly clear skies this
morning. This ridge will slide east of the state tonight.

Satellite depicting convective clouds over the mountains and
foothills. The rap model shows CAPE up to 200 j kg for this
afternoon. Expect snow showers to form this afternoon and evening
along the front range foothills and mountains where the best
instability will be and where an easterly upslope flow will
prevail. Snowfall could be quite heavy for a short time under
stronger snow showers with up to 2 inches in less than an hour.

The snow showers are expected to end by midnight as the airmass
stabilizes, however widespread light snow should form as a short
wave trough lifts northeast over the central rockies. Lift from
the short wave trough and easterly upslope flow is expected to
produce light snow into mid Monday morning. Snow will then end or
taper off to flurries as the trough exits the state. More snow
showers are expected to form Monday afternoon over the mountains
as the airmass destabilizes again.

East winds will continue to push cold air into the state today
and tonight. Expect temperatures to fall into the single digits
tonight and only climb into the teens Monday. Snow ratios will be
high, approximately 20 to 1 ratio. Expect the foothills to see the
most snow because of the convection this afternoon and evening
and due to the easterly upslope flow. Here, thinking 2 to 5 inches
with a few higher amounts due to the convection. For denver,
around an inch on the northeast side to 3 inches over southwest
denver. Again locally higher amounts will be possible under the
stronger snow showers.

Long term (Monday night through Sunday)
issued at 232 pm mst Sun feb 17 2019
a complex upper level trough will extend from the northern rockies
into the southern rockies Mon night and is fcst to form into one
main elongated upper level low on Tue from WRN wy into WRN co.

Meanwhile at the sfc, cold high pres will extend from the nrn
rockies into the central us.

Overall mid level flow will be south to southwest Mon night into tue
with a decent amount of QG ascent late Mon night into Tue with
marginal lapse rates. Meanwhile low level flow east of the mtns
will generally be southeasterly. For the mtns orographics will be
rather weak with most locations only seeing light snow. Only
exception might be over SRN areas of zn 34 and across the valleys
of park county where southeast flow can produce decent snow.

Over northeast colorado forecast is rather complicated due to
southeast low level flow and impacts from a denver cyclone that will
be in place. Position of the upper level jet would favor areas of
the far ERN plains late Mon night into Tue for the best area for
decent snow with much lighter amounts further west along the front
range. However, southeast low level flow could allow for higher
amounts in and near the NRN foothills from fort collins north to the
wyoming border. Other wildcard is the denver cyclone which, if
strong enough, could turn winds more to the east from denver
northward which would allow for a better shot of snow over the nrn
suburbs of denver to boulder and northward. At this point still a
lot of questions so will just keep likely pops in for Mon night into
tue with light amounts. As for highs temps will remain well below
normal with readings in the mid teens to lower 20s across the

By Tue night the main upper level will move across into early wed
with some additional QG ascent. Once again low level flow across
the plains will be south to southeast as a denver cyclone remains in
place. As the main upper level trough moves across there will be
some additional light snow across the plains. Further west along
the front range the low level flow will become more north to
northeast as the cyclone shifts eastward. As a result this may
enhance upslope flow Tue evening, and as main trough moves across
this could see some enhancement of snow in the evening along the
front range urban corridor. In the mtns will see some light snow
tue night as well.

For Wed the upper level trough will be east of the area with drier
flow aloft moving across. Outside of a few snow showers in the mtns
it will be dry with moderating temps as readings rise into the lower
to mid 30s across the nern co.

On Thu an upper level trough will intensify over the WRN us with
increasing west to southwest flow aloft. Some moisture will affect
the mtns by aftn which may lead to a chc of snow. Across nern co it
will be dry with temps remaining in the 30s.

For late Thu through Fri night there isn't much agreement between
the ECMWF and GFS with the handling of the upper level trough. The
ecmwf shows an elongated upper level trough moving slowly eastward
into the great basin with a substantial amount of energy moving into
the swrn us. Meanwhile the GFS has an upper level trough moving
across the area on fri. Although the upper air patterns don't match
up well they do show a couple of things. First off, both models
do show favorable mid level ascent Thu night into fri, and
secondly, a cold front is fcst move across nern co enhancing
upslope flow. Thus despite the upper air patterns not matching up
both models would produce some snow across the area along with
colder temps.

By Sat the upper level trough will move either to the east or
southeast of the area with pcpn chances ending.

Aviation (for the 06z tafs through 06z Monday night)
issued at 817 pm mst Sun feb 17 2019
light snow will be present across the are tonight into early
Monday morning. Heavier snow showers could cause localized lifr
conditions until 06z. A quick inch or two will be possible with
any heavier snow showers. At kden, expect around an inch of snow
by Monday morning with kapa could receive two to three inches with
heavier bands. Snow will end around 16z Monday morning. Clouds
will also lift, due to the southerly downsloping winds through

Bou watches warnings advisories

Update... Sullivan
short term... Meier
long term... Rpk
aviation... Sullivan

Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Fort Collins/Loveland - Northern Colorado Regional Airport, CO16 mi67 minE 58.00 miLight Snow17°F12°F80%1022.9 hPa
Greeley, Greeley-Weld County Airport, CO21 mi67 minE 910.00 miPartly Cloudy17°F5°F59%1025.1 hPa

Wind History from FNL (wind in knots)
Last 24hrNW12N4NW10NW6CalmNW10SE11SE9E7N3CalmE5E5E10SE7E9E13NE14NE11NE9NE8NE9NE5E5
1 day agoN11NE12NE4CalmN5CalmSE3CalmN3SE3CalmSE5E6E11NE5SW12N11
2 days agoSE8SE4E4E7E5NE8N9NE6NE5NE6NE4CalmNE64SE5SE8E11SE11E14E6SE11SE7W4NE6

Tide / Current Tables for
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Weather Map and Satellite Images
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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.
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Wind Forecast for Denver/Boulder, CO (0,6,7,8)
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Ground Weather Radar Station Cheyenne, WY
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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 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 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.