textproduct: NWS Phoenix

UPDATE

Updated 00Z Aviation Discussion.

KEY MESSAGES

- Dry conditions with mostly sunny skies can be expected today, but flooding of area creeks, streams, and rivers will continue through least tonight, following runoff from significant rainfall 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 over the next several days, with lower desert highs gradually rising from the mid 70s to upper 70s by the end of this week.

SHORT TERM /TODAY THROUGH WEDNESDAY/

Latest 3-day gauge measured rainfall and radar estimates show a large area east and northeast of Phoenix, in the foothills and higher terrain, received 5-7 inches and a few spots reached 8 inches. Even though the rain has ended, there is still a significant amount of runoff moving through the water systems across central AZ. Several USGS and flood control streamflow gauges are still above designated action/alarm stages and some are currently in minor to moderate flood stage. Many areal and river flood warnings will remain in effect through the rest of today. Unlike winter and spring snowmelt runoff following a rain event, should subside more quickly. However, some of the major waterways and watersheds, like the Salt and Verde systems, will take longer to subside. Possibly through even most of the week. Salt River Project will continue releasing a very high volume (over 60000 cfs) of water from Bartlett Dam into the Verde River, and from Granite Reef Dam into the Salt River. Impacts on the Salt River downstream of Tempe Town Lake can be expected as high flows continue. 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. Latest mid-lvl wv imagery and 500 mb streamline analysis reveals the trough of low pressure that passed through our region yesterday is now entering the Midwestern U.S. while a shortwave ridge builds in behind this feature over the West Coast. Winds will be somewhat breezy this afternoon on the backside of the departing trough, mainly along the lower Colorado River Valley where gusts could reach 20-25 mph at times. However much of the region will experience light winds and clear skies through the rest of this afternoon with highs reaching the mid 60s to low 70s across the lower deserts. Winds will greatly diminish tonight after sunset, becoming very light and calm across the area. With clear skies and light winds along with residual sfc moisture left over from yesterday's rain event, there is a chance that patchy fog could develop in low lying elevations early Tuesday morning. The most likely location for fog development will be N Pinal County and the Imperial Valley.

The aforementioned shortwave ridge will pass over the forecast 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 Tuesday and Wednesday will rise by a few degrees area-wide, but still remain around 5 degrees below normal, with lower desert communities reaching the middle low to mid 70s. 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 0030Z.

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 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. Skies will be mostly clear 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 at KBLH, will be out of the NW with speeds around 8kt into the overnight hours, then winds will go light and variable and may even be calm at times. Winds at KIPL will be light and variable to calm throughout the period. Clear skies will prevail before some high cirrus cloud decks move in this evening.

FIRE WEATHER

Lingering floodwater runoff in area creeks, streams, and rivers is likely to continue through tonight. 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.