textproduct: NWS Phoenix

UPDATE...Updated 18z Aviation Discussion

KEY MESSAGES

- Dry and mostly sunny skies today, but flooding of area creeks, streams, and rivers will continue today, following the rain over the past few days.

- Flooding in some of the major waterways like the Salt River may persist through the week. - Dry and seasonal weather conditions are expected through the next seven days, with lower desert high temperatures in the seventies to around eighty.

SHORT TERM /TODAY THROUGH WEDNESDAY/

Water vapor satellite and surface observations early this morning showed dry air was quickly spreading across the region, as the upper level trough was ejecting eastward through the Four Corners. Rain showers were also finally coming to an end across south- central AZ. A lot of water was transported in and squeezed out of the atmosphere over the past 3 days. Latest 3-day measured rainfall and radar estimates show a large area east and northeast of Phoenix, in the higher terrain, received 5-7 inches and a few spots reached 8 inches. Even though the has ended there is still a lot of runoff moving through the water systems across AZ. Several USGS and flood control streamflow gauges early this morning were still above designated action/alarm stages and some were in minor to moderate flood stage. Many areal and river flood warnings were still in effect and will remain in effect through most of this morning. Unlike Winter and Spring snowmelt runoff following a rain event, runoff following this rain event should subside more quickly. Still, runoff in some of the major waterways and watersheds, like the Salt and Verde systems, will take longer to subside. Possibly even most of the week. Salt River Project this morning around 3 AM MST was still releasing a very high volume of water from Bartlett Dam into the Verde River, over 60000 cfs, and from Granite Reef Dam into the Salt River, over 34000 cfs. Impacts on the Salt River downstream of Tempe Town Lake will likely develop today as runoff continues. Recreating in the Verde and Salt rivers will be very dangerous and is strongly discouraged. There have been multiple fatalities from recreation with similar flows in the past. Continue to heed all road closures as will and do not attempt to cross flooded roads.

Besides the lingering flooding, it will be a very pleasant Fall day, with high temperatures this afternoon forecast to reach the low to middle 70s under mostly sunny skies. Winds will be light across south-central AZ and there will be some northerly breezes up to 15-25 mph along the lower Colorado River Valley this afternoon. Dry conditions will continue Tuesday and Wednesday and temperatures will gradually warm. A shortwave ridge will pass over the area tomorrow between the departing upper level trough and another Pacific low. Model guidance keeps this next Pacific low on a west-east trajectory through UT and CO on Wednesday. Just about all this transient low will do to the local area is suppress heights and keep temperatures from warming more quickly. High temperatures Wednesday will be a bit closer to seasonal levels, but still ~5 degrees below normal, with lower deserts reaching the middle 70s to near 80 degrees. Morning temperatures the next few days will be seasonally cool, mostly in the 50s across the lower deserts and 40s in higher elevation communities and some of the typically cooler lower desert valley spots.

LONG TERM /THURSDAY THROUGH SUNDAY/

The long term forecast remains dry and seasonal. There is now much better confidence in the late week and weekend forecast, which favors ridging building in across the West and a weak cutoff low forming over the Pacific west of Baja California. Weak troughing looks to drag across the local area Friday into Saturday ahead of the building ridge. Previous forecasts supported slight rain chances with this trough, but this trough now looks completely dry and latest NBM PoPs are 5% or less across the region. These are also the only PoPs in the 7-day forecast. Plenty of time to dry out fallowing all the rain. Temperatures during the second half of the week will remain steady near to slightly below normal and then heading into the weekend temperatures are likely to trend warmer as the ridging builds into the west. Most lower deserts may see high temperatures return to the low and possibly even mid 80s.

AVIATION

Updated at 1720Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; No aviation weather issues are expected throughout the TAF period. The overall wind pattern will follow the more typical diurnal tendencies with westerly winds persisting through early this evening before shifting out of the east during the late evening hours with speeds generally aob 6 kts. Extended periods of light and variable to even calm conditions can be expected. FEW cumulus clouds with decks aoa 6 kft can be expected this afternoon with some high cirrus cloud decks moving in during the overnight period.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather issues are expected throughout the TAF period. Winds will generally prevail out of the west to northwest at KIPL and out of the north at KBLH with speeds aob 10 kts, although some occasional gusts in the mid to upper teens will be possible at KBLH this afternoon. Clear skies will prevail through this afternoon before some high cirrus cloud decks move in by early this evening.

FIRE WEATHER

Lingering floodwater runoff in area creeks, streams, and rivers is likely to continue through at least today. Otherwise, rain has ended and dry seasonal conditions can be expected through the next 7 days. Saturated grounds will help keep surface humidity levels somewhat elevated. Afternoon minimum RHs today will be around 50-60% across AZ and 25-35% across southeast CA. Despite gradual drying through the week, the minimum RHs will only fall to around 35-45% across AZ and 20-30% across southeast CA. Overnight recoveries will remain good through the week, with around 60-80% max RHs most nights. Winds through the next 7 days will mostly follow typical diurnal trends with light speeds and modest afternoon upslope gusts. Some breezier north winds may develop along the lower Colorado River Valley at times, but with only minor gusts up to 20-25 mph forecast at this time.

PSR WATCHES/WARNINGS/ADVISORIES

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