Good Chance of Rain Tuesday - Thursday, Maybe Even Snow

15 December 2014   Dr. Curtis James
No warming expected in the near future.

The figure above indicates the forecasted high in orange (with error bar denoting the range of ensemble forecast members), average high for this time of year in orange (dashed line), forecasted low in blue (with error bar), average low this time of year in blue (dashed line), and forecasted wind speed in purple. Note that the wind speed forecast is sustained wind (not gusts), and it is based on only one model (not an ensemble). 

Weather Discussion:

A longwave upper-level trough of low pressure will slowly shift across the southwestern U.S. this week, with several faster-moving shortwave disturbances moving across Arizona through the longwave trough. Lifting from these disturbances and strengthening pressure contrasts will create breezy and cool conditions across northern Arizona with a chance of rain Tuesday Night – Thursday.

There is great deal of uncertainty as to the strength of the last disturbance on Thursday, which would affect the temperatures in the upper atmosphere and determine whether or not temperatures will be cold enough for snow to fall here in Prescott. One of the operational weather forecast models (the Global Forecast System) is indicating a much weaker disturbance on Thursday, with only light rain showers for Prescott (snow levels around 6,000’). Another operational forecast model (the North American Model) is indicating a much stronger upper-level trough for Thursday with snow levels near 5,000’ and sufficient lifting for perhaps 2-3” of snow.

Bottom line is, a good chance of rain Tuesday night – Thursday, possibly changing to snow Wednesday night to Thursday.

C. James

Met Mail is an unofficial weather discussion and forecast transmitted once or twice a week via e-mail by the Embry-Riddle Department of Meteorology (http://meteo.pr.erau.edu/). Embry-Riddle offers an undergraduate bachelor-of-science degree program in Applied Meteorology. Please spread the word to all potential qualified candidates!

Further Information:

ERAU Applied Meteorology degree program

Official National Weather Service forecast

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