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 June 26, 2008
The Week in Review
Summer was in full swing this last week in the high country of RMNP, with warm temperature cycles well above freezing each day and night near 11 kft.
With a trough of low pressure approaching from the northwest and higher pressure to our south and southwest, the winds are currently increasing to moderate levels near mountain top.
Another familiar sign that summer has returned to the high country is the presence of deep convective activity on a daily basis. Lightening and heavy precipitation associated with deep convective thunderstorms pose the greatest summer weather risk to climbers.
While forecasting the exact location where these storms will form is still beyond our current capabilities, knowledge of forecasted environmental conditions (which have become quite reliable over recent years) and local mountain-valley circulation patterns can help hedge ones odds in avoiding these rumbling beasts. Two important environmental conditions which control the formation of deep convection include the vertical structure of moisture and temperature in the atmosphere. More detailed analysis of these profiles, including web resources, will be discussed in the weeks to come.
The passage of a couple of weak weather disturbances last Sun. and Mon. created environmental conditions favorable for widespread convective activity. This included an increase in moisture, a decrease in temperature above 18 kft, and ascending environmental air.
In contrast, the convection which occurred during the remainder of the week was forced primarily by the daytime heating of the terrain and the resulting local mountain-valley circulations. Since water vapor levels have only been modestly moist, only isolated thunderstorm activity resulted. The higher cloud bases associated with these conditions can produce gusty outflow winds, as precipitation evaporates and cools the surrounding drier air below the cloud base.
The Upcoming Weekend
As the northwestern trough of low pressure brushes by the northern part of the state, expect thunderstorm activity to increase in coverage over the high peaks on Fri. However, the forecast for the weekend is looking much more favorable for good climbing weather. Once the system moves east of the Divide later on Fri., drier air is forecast to move into the region with northwesterly flow. This will effectively remove the fuel levels needed to feed deep convective storms.
Since RMNP will be on the northeastern boundary of the moist air on Sat., it still may be possible to pop a storm or two over the southern region of the park. Sun. may be the glory day, as the atmosphere is forecast to stabilize even more and remain dry.
The official NWS numerical forecast for the Longs Peak area is as follows:
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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