Marine Weather and Tide Forecast for Sierra Vista, AZ

DISCUSSION
Today will be similar to yesterday with high pressure still in place over the southwest and temperatures 3 to 10 degrees above normal. Just enough moisture will be in place for an isolated storm or two over the White Mountains as well as Cochise County. Winds will also be easterly with some breezes in the Gila River Valley through Saturday. Friday the ridge begins to weaken some as a small closed low ahead of a larger Pacific trough moves south along the California coast. This is what will cause Hurricane Rachel to begin its northeastward turn towards Baja. Temperatures Friday will be similar to today with another slight chance for storms in the White Mounatins. The 08/06Z HRRR is also showing isolated storms from Tucson westward, likely initiated from early moisture advection. PWATs could be as high as 1.25" by Friday afternoon. However, confidence in this storm activity is low given it's only the HRRR showing this and no other HRRR or REFS members.

Much better and more widespread rain chances begin this weekend into early next week as tropical moisture interacts with a Pacific trough. Saturday into early next week a Pacific trough sets up over the West Coast. At first moving inland over the Pacific Northwest then digging south and absorbing the aforementioned small closed low by Monday. Rachel is expected to weaken to a tropical storm in the next few hours, and will likely be post-tropical when its remnants make landfall late Saturday or early Sunday morning. The current NHC track has Rachel making landfall over northern Baja California, then moving up the lower Colorado River Valley. This will lead to an increase in moisture for southeast Arizona beginning Saturday with PWATs around 200 percent of normal. Expect scattered moderate showers Saturday and Sunday with some embedded thunderstorms. The heaviest rain at this time looks to be a little further north over central Arizona. The trough will also bring breezy to windy conditions Sunday and Monday afternoons with speeds 15-30 mph and gusts to 40 mph. Winds will be strongest on Sunday.

Rachel will not be the only tropical system to watch over the next few days. Newly named Simon is currently centered a couple hundred miles west/southwest of Acapulco. Over the next day or so it is forecasted to strengthen into a Hurricane and move northward reaching central Sinaloa late Monday night. This will send re-enforcing tropical moisture towards southeast Arizona keeping PWATs around 200 percent of normal through at least Tuesday. On its current trajectory the best moisture will be just east in New Mexico, but it will be enough to keep rain chances going into Tuesday and Wednesday.

Current forecast rainfall totals Saturday into Tuesday are 0.25"-1.00" in the valleys and 1.0"-2.0" in the mountains. This is more of a long duration rain event and flash flooding is not expected. But by Monday and Tuesday area washes could have some flow in them depending on rainfall amounts. Still some spread in the QPF forecast so expect these rainfall amounts to fluctuate as the weekend and early next week approaches.



AVIATION
Valid thru 09/12Z.
FEW-SCT clouds 8k-12k ft AGL through the forecast period with BKN cigs into this evening from KSAD northeastward and along the international border. Isolated -SHRA/-TSRA will be possible across northern Greenlee County as well as Cochise County.
Likelihood of any terminals being affected by TSRA is low. SFC winds E/SE 6-12 kts through the period. Aviation discussion not updated for TAF amendments.

FIRE WEATHER
Easterly winds return today into Saturday with the strongest winds in the Gila River Valley Friday with gusts 20-35 mph. Minimum relative humidity values will remain 15-30 percent in lower elevations and above 40 percent in high elevation terrain through Saturday. A few storms are possible for the White Mountains and Cochise County this afternoon and again Friday afternoon. A weather system will begin to move in this weekend bringing a 30-70 percent chance for rain Saturday through early next week. This system will also bring breezy to windy southwest winds Sunday and Monday.

TWC WATCHES/WARNINGS/ADVISORIES
None.