SYNOPSIS
Thunderstorms will remain situated closer to higher terrain areas north and east of Phoenix through the weekend as drier air begins filtering into the region. Temperatures will also retreat somewhat closer to the seasonal normal as high pressure weakens and shifts into northern Mexico. This trend will continue through around the middle of next week before a warmer and more humid airmass returns to the region supporting increased thunderstorm chances.

DISCUSSION
Early morning satellite depicts a complex of showers and storms that have blossomed over southeastern Arizona, with a gravity wave emanating to the north and interacting with a shortwave moving across the region resulting in elevated convection into portions of Pinal and even far southeastern Maricopa County. Hi- res models show this convection persisting over the next few hours prior to dissipating by daybreak, thus elevated PoP's of 30-40% are present in the very near-term forecast for the general areas where the convection has developed. The current convection is expected to be the main activity for today across the region, as the drying trend will continue to erode away favorable shower/thunderstorm conditions over the weekend. For today, the majority of the activity is expected to remain in far eastern Gila County, with convection either struggling to migrate off the higher terrain features, or the general motion will move out of the forecast area to the east or south. Temperatures will remain above normal, although most lower desert locations may see highs dip below 110 degrees by Sunday.

This decrease in thunderstorm activity is due to the subtropical high pressure retreating southward centered generally over the Baja Peninsula, as a shortwave traverses across the Great Basin over the weekend. This trough will keep deep layer westerly to southwesterly flow into early next week. Thus, daily shower/thunderstorm chances will continue to diminish, with higher terrain areas of southcentral Arizona only around a 30-40% chance over the next several days. Ensembles are in excellent agreement on the subtropical high building back across the region early next week, with the high center located over the southern Plains by Tuesday. The upper level flow response will back more towards the south, but the return of moisture to the region remains stunted, as PWAT's remain around 1.25" across southcentral Arizona going into the latter portions of next week. As a result, there remains low chances for thunderstorm activity, relegated to the higher terrain areas during this period.

Looking towards the latter portions of the week and into next weekend, ensembles remain in excellent agreement on ridging over western CONUS becoming more amplified and strengthening to 597-600 dam, with the high center migrating back over the four corners region. This pattern change would introduce more deep layer monsoonal flow, so a return of moisture and increasing thunderstorm chances would be expected. However, the more favorable flow is looking delayed to more Friday onward, where ensembles generally show PWAT's beginning to bump upwards more towards 1.50" going into the weekend. Based on the current forecast, NBM PoP's begin to show a discernible increase starting Friday across the higher terrain, but any lower desert activity will likely remain limited to next weekend. Temperatures throughout the extended period will continue to run several degrees above normal, with warming of a few degrees by the end of the week.

AVIATION
Updated at 1155Z

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation concerns are expected during the TAF period. Winds will follow diurnal trends, with gusts during the afternoon hours around 20 kts. Isolated showers and thunderstorms are once again expected over the Arizona high terrain this afternoon, but should remain well outside the vicinity of metro terminals. A strong outflow from this activity cannot be completely ruled out, but chances (10-20%) are much lower compared to the previous several days, and therefore mention of one of these features is not included in the TAFs at this time. Hi-res data is trying hint at some rainfall activity closer to the terminals late in the period, but chances during this timeframe are too low to include mention of any SHRA in the TAFs. FEW, to occasional SCT mid and high level clouds will be present, with the lowest bases around 12k ft.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation concerns are expected during the TAF period.
Winds at IPL will contain a W'rly component through Sunday morning, with gusts this evening upwards of 25 kts. Familiar diurnal trends should be anticipated at BLH, with gusts 20-25 kts during the afternoon and evening hours. Other than a FEW passing high clouds, skies should be mostly clear through tonight.

FIRE WEATHER
Thunderstorm chances should remain confined primarily to the higher terrain areas of eastern districts through the beginning and middle of next week, with chances lessening each day. CWR's will remain less than 10% through the middle of next week. Aside from any thunderstorm outflows, winds will follow typical upslope/downvalley patterns with intermittent afternoon gusts in the 15-20 mph range. Minimum humidity values will trend drier through early next week with lower elevations falling into the teens while eastern district higher terrain near 25%. This will follow widely varying overnight recovery ranging from poor 20-25% in western districts to fair to good 40-60% in eastern districts.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...None.
CA...None.