Monday, June21, 2021
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Marine Weather and Tides
Granby, CO

Version 3.4
NOTICE
3/30/2021 -- ANZ330 has been split into ANZ331 and ANZ332. Click EDIT in Marine Forecast and select your new zone.
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

Sunrise 5:30AMSunset 8:35PM Monday June 21, 2021 12:09 AM MDT (06:09 UTC) Moonrise 4:19PMMoonset 2:02AM Illumination 85% Phase: Waxing Gibbous; Moon at 11 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 Granby, CO
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location: 40.15, -105.89     debug


Area Discussion for - Denver/Boulder, CO
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FXUS65 KBOU 210201 AFDBOU

Area Forecast Discussion National Weather Service Denver/Boulder CO 801 PM MDT Sun Jun 20 2021

UPDATE. Issued at 801 PM MDT Sun Jun 20 2021

Cold front is pushing south across northeast Colorado at this time and will pass through the Denver area between 8pm and 9pm. Northeast winds gusting to 25 mph will prevail after it pushes through. Scattered rain showers have been forming behind it. Lift from the jet is producing more widespread showers and isolated thunderstorms over central and southeast Wyoming. This will slide southeast through the rest of the evening. Increased PoPs more with rain very likely for most of northeast Colorado. Amounts not all that impressive with less than a half inch expected.

SHORT TERM. (This evening through Monday) Issued at 156 PM MDT Sun Jun 20 2021

This morning's cold front has stabilized the plains, while dry air remains over areas west of the Front Range. We're still looking for a few weak showers and storms to form over the central mountains where there's a little more moisture. A few of these may survive moving across the Colorado Springs area towards southern Lincoln county where there hasn't been as much cooling. Otherwise, we'll be waiting on the lift associated with the shortwave trough which is now dropping south across central Wyoming. There are increasing clouds behind a stronger secondary cold front that will pass across our area early this evening. However, this still looks to be capped by a stable layer between 600-450 mb, so if there are any showers they should not be very productive. The shallow instability will get deeper with a little cooling aloft that will drop from the northern border before midnight across the plains late tonight. This will allow for a period of more general rain, probably for 4 to 6 hours as this feature passes. By sunrise Monday, this will likely have pulled east of the mountains but there may still be some showers on the plains. There will be warming and drying aloft during the day Monday, but it will take a little while to burn off the low clouds as there's no sharp drying at the surface. West of the Front Range there may be a few showers overnight as the trough passes, but the bulk of the lift comes from the overrunning and convergence east of the mountains. With the warming/drying aloft we should be stable tomorrow afternoon, though some isolated weak convection over the central mountains may be possible again.

The main change with this package is slowing the arrival of the rain a little this evening along with slightly cooler temperatures overnight.

LONG TERM. (Monday night through Sunday) Issued at 156 PM MDT Sun Jun 20 2021

Monday night should be relatively quiet, with lows in the 40s across the high terrain and 50s for the plains. The cool weather from Monday will be short lived as an upper level ridge axis builds over the state. Low to mid 90s will be the theme across the plains, with 70s for the mountains and 80s for the high valleys. It will also be pretty windy across the higher elevations, which will lead to some fire danger concerns, which are discussed further below. Forecast soundings show almost no moisture to work with and only about 100-200 J/kg of CAPE, so virtually the whole forecast area should stay dry.

Wednesday looks to be the hottest day of the week, with highs in the mid to upper 90s for most of the plains. There's just enough moisture and instability to work with during the day to see a few thunderstorms, but this activity should largely stay confined to the mountains and across South Park.

Model solutions then begin to diverge Thursday and beyond, with substantial differences emerging by next weekend. There is reasonable agreement in a large-scale trough axis working across the northern U.S. by Thursday, with a cutoff low or second trough centered west of California. We should see highs in the upper 80s to low 90s during the afternoon, with better chances of afternoon showers and storms across most of the forecast area.

Much more uncertainty exists for Friday and next weekend, with the GFS/ECM now suggesting a stronger northern trough and much cooler weather than previous cycles had shown, in addition to a fairly widespread precipitation event sometime in that period. The spread in the ECM ensemble for Friday and Saturday's highs range from the low 70s to upper 90s. The current forecast lies near cooler than the center of this range, with highs near 80 and PoPs right around 40-50%. Expect changes to the forecast as confidence increases.

AVIATION. (For the 00Z TAFS through 00Z Monday evening) Issued at 801 PM MDT Sun Jun 20 2021

Northeast winds will continue overnight behind a cold front. Gusts to 25 knots will be possible as the front pushes through, between 0230Z and 03Z. Rain showers will form behind the front along with a few weak thunderstorms. Clouds will continue to lower through the night with ceilings falling below 2000 feet around 06Z. Low clouds will be slow to burn off and lift Monday morning. Expect ceilings of 3000 to 6000 feet into early Monday afternoon before clouds scatter out.

FIRE WEATHER. Issued at 156 PM MDT Sun Jun 20 2021

Red Flag conditions in Jackson and Grand counties will ease with cooling this evening. Monday afternoon will be warm, dry, and breezy again, but with slightly lower temperatures and higher humidities and a bit less wind.

Critical fire conditions may re-develop Tuesday and Wednesday, especially across the high valleys. Hot temperatures are likely for Tuesday, with forecast highs in the mid to upper 80s across North and Middle Park. Lack of any substantial moisture will lead to humidities again in the 10-15% range. Forecast soundings at Walden and Kremmling show about 20-25kt winds through the boundary layer Tuesday, which should lead to gusts up to about 30-35 mph. Conditions will likely be similar Wednesday, with just a little less wind to work with. Though we held off on Fire Weather Watches in this forecast package, headlines will likely be needed for both Tuesday and Wednesday this week.

HYDROLOGY. Issued at 156 PM MDT Sun Jun 20 2021

Light rain is expected over the east slopes of the Front Range tonight, with a chance of light showers further west. The threat of burn area flooding is low. Little or no thunderstorm activity is expected on Monday. Tuesday and Wednesday should both be fairly dry with a low flood threat. Precipitation chances increase Thursday and into next weekend.

BOU WATCHES/WARNINGS/ADVISORIES. None.

UPDATE . Meier SHORT TERM . Gimmestad LONG TERM . Hiris AVIATION . Meier FIRE WEATHER . Gimmestad/Hiris HYDROLOGY . Gimmestad/Hiris


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Kremmling, Mc Elroy Airfield, CO26 mi74 minNW 8 G 1610.00 miFair59°F41°F51%1022.7 hPa

Link to 5 minute data for K20V

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Last 24hrCalmSE7CalmE3CalmSE3CalmCalmCalmCalmN3W11
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1 day agoCalmSE4E4E5SE4E8NW4CalmSE4E4E6W5W6W10
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NOTE: This section has been updated as of 1/26/2021. If the image you are expecting is not showing, please let me know. You may use the EDIT function to update your location.
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