The strong high pressure ridge that has persisted over the Southwest for the past week, keeping thunderstorms across Northern Arizona somewhat isolated, is weakening and shifting eastward while a low pressure system develops along the West Coast and cuts off. The combination of ridging to our east and a low to our west will continue to keep the flow aloft southerly and maintain enough moisture for a daily chance of thunderstorms through the weekend. Thunderstorm motion will generally be toward the north at about 10 – 15 mph. The main threats will be locally heavy rain, small hail, lightning, and gusty wind. Storms will generally remain non-severe.
Meanwhile, Hurricane Irma is now the strongest category (Cat. 5) hurricane and is approaching the West Indies and Puerto Rico. It could weaken slightly over the next several days, but is expected to remain a major hurricane as it approaches Florida Saturday-Sunday.
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!
ERAU Applied Meteorology degree program
Official National Weather Service forecast
Graphical Weather Forecast for the Prescott Area:
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).