Author: Ben Castellani (page 1 of 21)

What can weather radars tell us about bats?

We examine the fascinating amount of information about bats that can be gleaned from their signatures on weather radars!

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This week in weather: August 14, 2017

Our cool and wet prediction for the month of August has held true thus far. The city of Boulder is currently riding a streak of 17 consecutive days of below normal temperatures. Furthermore, the last 90-degree afternoon was nearly three weeks ago. Will the upcoming week continue the trend? Read on to find out!

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Rain overdue? A cool and soggy outlook for the month of August

It’s hard to believe that August is now upon us! Summer is almost half over. The month of July produced below normal precipitation and had a temperature nearly two degrees above average in Boulder. Should we expect more of the same in August? Read on as we examine Boulder’s climatology and consider the current state of the atmosphere to give our outlook for the next month.

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This week in weather: July 31, 2017

As we close out the month of July and move into the fourth week of monsoon season, somewhat drier air will take hold across Colorado and make for less storm activity overall this week. However, a significant cool-down is likely towards the latter part of the week ahead. Read on for details.

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DayCAST: Thu 07/27/17

How about that slow-moving monsoon storm last night in Boulder….definitely our most intense rainfall since late last summer.  Between 7and 9 PM, 0.5 to 1.0″ of rain was recorded as torrential rain pounded the city. The radar image from 7:42 PM is below, with the storm that affected Boulder circled in pink.

Radar image from Wednesday night at 7:42 PM. Monsoon storms!

Yesterday had a lot of solid meteorology working together to produce the heavier rainfall. Today we will not see quite as favorable of conditions. Moisture has dropped and the frontal boundary has pushed well south and east.

After morning sun, expect partly cloudy skies in the afternoon and storms forming after 2PM, first across the higher elevations. We expect storm coverage to be isolated across the Metro area, with scattered activity in the Foothills (especially south and west of Denver). Highs will remain cool in the lower 80’s.

Unsettled conditions will remain through the upcoming weekend, with at least isolated chances of storms each day.

Fujiwhara Effect! 

While checking the health of our monsoon flow for this forecast, I noticed a rare phenomenon in the models that is expected to happen between two tropical systems off the western coast of Mexico in the coming days. It is known as the Fujiwhara Effect and it happens when two nearby low pressure systems (normally tropical cyclones) orbit each other and spiral closer together. You can see this happening in the animation below between Tropical Storm Irwin (left) and Hurricane Hilary (right). Here is some additional reading from Wikipedia on this rare effect if you are interested.

Animation showing a likely Fujiwara interaction between two tropical cyclones off the western coast of Mexico this weekend.


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This week in weather: July 24, 2017

Much of our region has missed out on the monsoon thunderstorms so far. As we move into the last week of July, Boulder’s monthly rainfall total rests at just 0.32″. Normal for the month of July is right around 2″, so this is well below average. The week ahead will offer a resurgence of monsoon moisture to northeast Colorado. However, as always, not everyone will see the much needed soaking rains.

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Introducing SummitCAST, hiking forecasts for Colorado’s high country

Today we are excited to announce the launch of SummitCAST, our cutting-edge suite of localized forecasts for Colorado’s top hiking destinations. Read on for all the details and begin planning your next alpine excursion using the BEST mountain forecasts currently available!

To celebrate the launch of SummitCAST, through July 31st use the promo code SUMMIT to receive a 33% discount on an annual subscription to BoulderCAST Premium. The final price is just $26.80 per year!

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This week in weather: July 10, 2017

This week we discuss the arrival of the summer monsoon which will facilitate some of the best chances of rain we have seen in weeks.

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Tracking the arrival of the summer monsoon

With the first full-week of July coming to a close, monsoon season is right around the corner for northeast Colorado. However, its arrival is not something you can mark on the calendar as there is no set date for its commencement. It fluctuates substantially from year to year, depending greatly on the weather patterns of Mexico, the southeast USA, and the tropical eastern Pacific Ocean. We discuss the current state of the atmosphere and when we expect the monsoon to finally arrive. It’s already running a tad late.

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Forecast for Bike to Work Day 2017!

The last Wednesday in June has arrived, the day when thousands of hard-working citizens take to the bike paths for their morning and evening commutes. Yes, it’s Bike to Work Day 2017 tomorrow! Five out of the last ten Bike to Work Days have seen measurable precipitation in Boulder. How does tomorrow’s forecast look for the Metro area? Read on to find out if the bikers will be getting wet this year….

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This week in weather: June 26, 2017

While our forecast for the week ahead contains the chance of rain each and every day, we do believe that many locations won’t see a drop of rain at all this week. The roller-coaster ride of temperatures is the bigger story here.

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Possible hail Thursday & the cool weekend ahead

After record-setting heat the last two days, the first wave of cooler air arrives early this afternoon. Then, an actual cold front is set to move in later tonight. Before that however, we’ll have to survive a few hail-producing severe storms this afternoon.

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SOLSTICE ONLY: Celebrate summer with our biggest Premium discount ever!

For today only, in celebration of the first day of summer, use the promo code SUMMER to receive 40% off an annual subscription to BoulderCAST Premium, our biggest discount ever!

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