textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- Scattered showers with pockets of light rainfall will continue across southeast California and southwest Arizona through Saturday.

- This weather system will keep moving east through the weekend bringing scattered showers to central and eastern Arizona Saturday and Sunday morning.

- Temperatures will remain below normal this weekend, then return to near normal levels by the middle of next week.

SHORT TERM /TODAY THROUGH SUNDAY/

The secondary upper level trough that originate from the Pacific NW has now made it just off the coast of Southern CA. With it brought an increase in low to mid level moisture across SE CA and SW AZ. This has bumped PWATS to ~0.9-1.1" in the western parts of our region, bringing additional rounds of showers this morning with rainfall totals already between 0.5-.8" across most of the Lower Colorado River area. A Flood Watch remains in effect through 11pm PST/12am MST tonight as another 0.25-0.50" can be expected throughout this afternoon/evening. Fortunately or unfortunately, depending if you view the glass half full or half empty, the core of this current weather system is expected to move more quickly than the previous system and is forecasted to be over SE CA/SW AZ by late Saturday night. This will keep temperatures below normal for a couple more days with highs barely tipping over 60 degrees today, in the low to mid 60s Saturday, and warming slightly Sunday with highs in the high 60s to near 70 in some locations.

For Central and Eastern AZ PWATS are currently ~0.4-0.6", but will increase to just shy of 1" by early Sunday morning as the trough moves northeastward through Central AZ. this will have activity lingering throughout the weekend but, most activity will remain light/sprinkles and most may only be virga showers for the Phoenix Metro, and potential for 0.1-0.2" in the higher terrain and Gila County. Models show no instability with this round of activity, so no thunderstorms are expected across central and eastern portions of the state. Similar to the western portions of our region, afternoon highs are expected to remain below normal for a few more days with temperatures throughout Central AZ peaking today in the mid 60s, warming slightly for Saturday to the low 70s, then cooling back to the mid 60s on Sunday as the low pressure system exits our region. As just mentioned the low will be east of AZ Sunday night and quickly advect into the Plains on Monday. By then PWATS across the Desert SW will be back to under 0.7" nilling further shower activity by Sunday night.

LONG TERM /MONDAY THROUGH THURSDAY/

As we move into next week calm and tranquil weather conditions make a return to the Desert Southwest. The low pressure system that will bring rain to the region this weekend will be well to the east of the region by Monday. In the wake of the low pressure system, heights aloft will be around 574-577 dm on Monday slowly rising to around 578-581 dm by Thursday. This will result in a gradual warming trend through the workweek, with temperatures returning to near normal as early as Tuesday. Across the lower deserts afternoon high temperatures are forecasted to range from the mid 60s to low 70s rising to the low to mid 70s by the end of the workweek. For the higher terrain areas, afternoon highs on Monday will be in the low 60s rising to the upper 60s to low 70s by the end of the workweek. Additionally morning lows will range from the mid 40s to low 50s across the lower deserts and in the low to mid 40s across the higher terrain through the workweek. With rising heights aloft, forecast confidence is very good that dry conditions will prevail through this coming workweek.

AVIATION

Updated at 0500Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Other than some potential variability in wind directions late this evening, the likelihood of SHRA Saturday evening/overnight will the primary weather issue under persistent cloud decks with bases frequently in a 080-100 AGL range, then possibly lowering late in the period. KPHX may experience some wind direction variability before midnight, however confidence is good that east winds will settle across the region much of Saturday morning and afternoon before veering S/SW around sunset. More uncertainty exists Saturday evening, however most guidance suggests -SHRA with lowering cigs entering the metro mid/late evening.

Southeast California/Southwest Arizona including KIPL and KBLH: Periods of RA, local MVFR cigs, and potential for MVFR vsby will be weather issues through Saturday afternoon before flight conditions improve. With N/NW winds generally prevailing, flight categories should be worst and persist the longest at KIPL where occasional MVFR cigs may occur with the next round of -RA late tonight and Saturday morning. Confidence is good that -RA ends at KBLH late tonight with improving conditions by sunrise and throughout the day. However, continued -RA with the potential for reduced vsby and lowered cigs will continue into Saturday morning and early afternoon at KIPL before improving late afternoon/early evening.

FIRE WEATHER

Below normal temperatures and elevated moisture will remain in place keeping MinRHs in a 40-70% range following excellent overnight recovery greater than 80%. Locally gusty winds upwards of 20 mph will be possible at times, though weaker wind speeds will be more common through the period. A weather system will be moving mainly across the western districts today leading to very good chances for wetting rains with more scattered shower activity across the eastern districts Saturday through Sunday, with Sunday expected to be the final day of activity. Temperatures will mostly remain below normal through the weekend with humidities staying elevated. Temperatures will return to near normal as early as Tuesday.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...None. CA...None.