The weekly weather forecast for the high country of Rocky Mountain National Park, Colorado; researched and written by professional meteorologist and avid mountaineer: Dan "the weather man" Gottas.
Issued Thursday July 10, 2008
The Week in Review
An upper atmospheric disturbance moved over the region last weekend. This large scale pressure wave allowed moist subtropical air, originating in Mexico, to surge northward over Colorado, and was essentially our first taste of the North American Monsoon of the season.
With the increase in cloud coverage and precipitation for the two days ahead of the pressure minimum (which occurred on July 7th), daytime high temperatures were 10 – 15 degrees F colder than the previous few days. In addition, the isolative properties of the overcast skies acted to keep the diurnal temperature spreads small.
With the slower daytime heating rate induced by the extensive cloud coverage, afternoon thunderstorms were slow to develop, leaving more bark than bite prior to 3pm. While heavier showers were confined mostly to the deeper convective cells after 3pm, large-scale forcing, orographic forcing, and weak daytime heating were enough to support scattered spitting around the clock over the higher terrain.
After the pressure wave passed to the east of Colorado on Monday, a drying trend began. By Thursday (July 10), very low levels of atmospheric water vapor moved into the region, which limited the moist convective activity to just shallow fair weather cumulus clouds mainly over the eastern sections of the park.
With RMNP currently positioned on the south side of the polar jet stream, subsiding, dry westerly air flow has produced a vastly dry and stable airmass from California to Colorado. In addition, the moist, subtropical plume associated with the monsoon is now well south and east of RMNP.
The Upcoming Weekend
With respect to safe weather, all systems are GO for higher, committing alpine ascents over the next couple of days (Friday and Saturday). Shallow cumulus cloud development will be the extent of the afternoon weather activity, and so the lightening risk will be non existent. With an abundance of direct sunshine (over 1000 Watts per square meter up on the high peaks), the greatest weather-induced risks will be sun burn and dehydration.
For Sunday, the atmosphere may moisten up a bit east of the Divide. Even if this verifies, the threat of precipitation and lightening will remain low, with mostly an increase the convective cloud coverage and some thicker cloud depths. The temperature and wind forecast for the high peaks is as follows:
By Tuesday, subtropical moisture is forecast to creep back into the area from the southwest, as an anticyclonic circulation develops over New Mexico. With this, the risk of showers and thunderstorms will be on the increase.
Detailed 7-Day Forecast
The link above will take you to the National Weather Service forecast for the 12,000 foot level near Longs Peak. These forecasts are derived from computer-generated numerical forecasts, and are updated shortly after 3:30 am, 9:30 am, 3:30 pm, and 9:30 pm local time. In the lower right-hand corner of the page, one can view forecasts for other locations in the Park by clicking on the desired location in the terrain map.
Do-It-Yourself Weather Forecast Links
The link above provides a list of web links to various sites containing a variety of meteorological data and information. Collectively, these resources can be used to monitor and study current weather conditions, as well short-term, medium-range, and climate forecasts.
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