Catalina, AZ Weather

Synopsis

There will be a slight chance of showers and thunderstorms along the Arizona and New Mexico state line through mid-day Saturday. Dry conditions are then expected areawide Sunday into next week. High temperatures will be below normal into early next week, warming to near normal during the middle of next week.

Discussion

There's an old saying that was passed down to me from my grandma, "after a storm comes the calm." While today may not be entirely calm with a slight chance for light showers remaining along the Arizona/New Mexico border this afternoon, considerably quieter weather is in store for Southeast Arizona the next several days following our recent bout with turbulent weather.

The upper weather pattern this afternoon is defined by a mean trough across the NRN Intermountain West extending SSW into southern California...with the latest water vapor imagery indicating two distinct low centers across northern Nevada and central California. The recent GOES precipitable water imagery indicated a significant area of drier air has expanded into the area, with PWATs between 0.40 and 0.50 across Pima and Santa Cruz counties. Still some lingering moisture holding onto the Arizona/New Mexico border with PWATs ranging between 0.65 and 0.75 inches. This is supported by surface dewpoints early this afternoon, with values hovering from the mid 40s across far western Pima to the lower 50s in the Tucson Metro, and in the upper 50s in the Gila River Valley and along the AZ/NM state line. I would expect decent mixing this afternoon will bring the dewpoints in Tucson down into the mid 40s, but I am confident that higher moisture will persist out east, especially given the higher soil moisture content. The combination of weak mid- level lift east of the mean trough and this moisture along the AZ/NM border will result in a slight chance for light showers this afternoon, possibly persisting into mid-day Saturday. Otherwise, expect fair weather cumulus from Tucson east today and clear skies west.

The upper-low to our west eventually ejects NE this weekend with another kicker low developing along the Pacific Northwest coastline. Ensemble members are all over the place with regards to both the north/south and east/west position and movement of this feature with lots of variance evident on the Empirical Orthogonal Functions (EOF) of the GEFS/ENS/GEPS Sunday. In general we will see an upper-low develop, but the amplification and position will depend on the strength of the upper ridge building into the Gulf of Alaska. This has ramifications for what happens later next week, as both the deterministic GFS and ECMWF are trying to push a slug of subtropical moisture east toward the Desert Southwest next weekend. If the upper-low pattern remains an open wave for the majority of next week, we will see a strong zonal flow directing that moisture plume our way, possibly getting wrapped up ahead of the upper low as it swings into California. This potential heavy rainfall event is getting picked up by the grand ensemble of the NBM, with a 20-40 percent probability for a 48-hr rainfall in excess of an inch next Sunday and Monday (November 1-2) on the 23/12Z NBM run. Again, still a lot of variance in the early stages of this pattern setup, so my confidence is low on the timing and strengthof any pcpn event we may see (not this weekend but the next weekend).

Until then...enjoy the calm and take advantage of the beautiful weekend in store for Southeast Arizona.

Aviation

Valid through 25/00Z. SCT-BKN clouds at 5k-8k ft AGL east KTUS to the AZ/NM state line through mid-day Saturday. with a slight chance of -SHRA/-TSRA along the AZ/NM border. SFC wind southwest less than 12 kts west of KTUS, and 10-15 kts with gusts to 25 kts east of KTUS into this evening, then wind less than 12 kts and terrain driven overnight. Aviation discussion not updated for TAF amendments.

Fire Weather

High temperatures will be below normal through Monday, warming to near normal Tuesday and Wednesday of next week, then lowering back below normal by the end of next week. There will be a slight chance of showers and thunderstorms through mid-day Saturday along the Arizona and New Mexico state line and in the White Mountains. 20-foot winds will generally be 15 mph of less through at least the middle of next week. Minimum RH values will be in the 25-40 percent range in the valleys through Sunday (higher in the mountains), lowering into the 20-30 percent range next Monday through Wednesday.