textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- Above normal temperatures with minimal day to day changes will exist through the start of the week as afternoon highs reach 97 to 103 degrees across the lower deserts.

- Breezy to locally windy conditions can be expected in the mornings and early afternoons across south-central and southwestern Arizona through Monday with gusts reaching 20 to 35 mph.

- Temperatures across southeast California and southwest Arizona warm to near record levels Wednesday and Thursday.

- Dry weather with zero rain chances will persist through the week.

SHORT TERM /TODAY THROUGH TUESDAY/

Dry and warm conditions continue across the region with broad high pressure positioned over the Southwest CONUS. A strong E-W pressure gradient remains in place across southern AZ and has resulted in wind gusts today up to 30-40 mph across parts of south-central AZ. Several dust channels developed and were visible on satellite across Pinal County around midday. Magnitude of wind gusts are expected to wane through the afternoon and this evening. High temperatures this afternoon will be similar to yesterday for most areas and a couple degrees warmer across south-central AZ, topping out around 97-102 degrees.

Weather conditions heading into Monday will once again be similar to today with breezy easterly winds, as the pressure gradient persists, and above normal temperatures with afternoon highs again around 97- 102 degrees. Easterly wind gusts during the Monday are forecast to peak around 25-35 mph in the morning and then weaken through the rest of the day as the pressure gradient finally relaxes with lowering surface pressure to the east. By Tuesday, a shortwave trough, which is currently just off the CA coast, will move eastward inland through NV and UT and dislodge the high pressure over the region while also shifting mid-level flow from E-SE to W-NW. Despite these changes aloft, there will not be any notable immediate changes at the surface. Temperatures Tuesday will remain nearly unchanged at 5-10 degrees above normal with highs around 97-103 degrees across the lower deserts. The surface pressure gradient will at least relax further into Tuesday. There may still be some morning easterly breezes, but overall winds will be much lighter Tuesday across the region. Skies will remain mostly clear through the start of the workweek with no rain expected

LONG TERM /WEDNESDAY THROUGH SATURDAY/

By Wednesday, a quasi-omega block is shown to develop with an anticyclone developing near/over the SoCal coast. Forecast confidence is good that this pattern will hold through the end of the workweek. This will result in temperatures remaining fairly steady across south-central AZ with afternoon highs in the 95-100 degree range across the lower deserts and ranging from the mid 80s to lower 90s across the higher terrain areas. Meanwhile temperatures are expected to heat up across southeast CA and southwest AZ with a strengthening of the nearby anticyclone. Latest NBM forecast continues to show afternoon highs reaching the 100-106 degree range across the lower deserts in SE CA and SW AZ for both Wednesday and Thursday. These temperatures will be over 10 degrees above normal and near daily records in both El Centro, CA and Yuma, AZ both days. These temperatures also will likely lead to Major HeatRisk for this time of year, with probability of Major HeatRisk at 50-70%. As a result, an Extreme Heat Watch has been issued for the Yuma area and Imperial Valley for Wednesday and Thursday. With high pressure in place dry conditions are expected to persist with no chances for rain, except for near the White Mtns Wednesday with a weak shortwave moving through the Four Corners.

The high pressure to the west is then expected to start to weaken by the end of the workweek and into the weekend with a trough moving into western CONUS this upcoming weekend. However, forecast confidence decreases considerably by the end of the weekend and start of the following week as the ensemble spread is large with the timing of the high weakening and moving out of the region and the trough moving in. The ensembles also disagree on the strength of the trough for this upcoming weekend. Either way temperatures are expected to gradually decrease back toward normal by this upcoming weekend. Additionally, dry conditions look to continue through at least Saturday, but this could change depending on the evolution of troughing during the weekend. Right now better chances for rain look to arrive by the beginning of next week, with the best chances across the higher terrain in eastern AZ. Stay tuned for updates.

AVIATION

Updated at 2320Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Under clear skies, the primary weather issue through Monday evening will frequently gusty east winds. Confidence is moderate that some measure of gustiness will persist through the evening as decoupling may never fully be accomplished overnight. As a result, LLWS conditions may only be reached at the most sheltered aerodromes with steady wind speeds and occasional gusts through the night elsewhere. Confidence is very good that easterly gusts 20-25kt will redevelop Monday mid morning before relaxing mid afternoon. While some dust may locally be lofted with these wind gusts, the limited temporal and areal expanse should preclude surface or slantwise visibility issues.

Southeast California/Southwest Arizona including KIPL and KBLH: No weather issues will exist through Monday evening under clear skies. Confidence is good that wind directions will oscillate between a daytime E/NE and overnight N/NW with speeds occasionally reaching 10-12kt.

FIRE WEATHER

Expect easterly winds to remain elevated around 8-15 mph with early morning and afternoon gusts up to 20-35 mph, and locally higher gusts of 35-40 mph, today mainly across SW AZ and the eastern district. Winds will be a touch weaker Monday and then winds will return to their more typical light diurnal tendencies on Tuesday with only minor afternoon upslope gustiness. These lighter winds may only last a couple days before gusty easterly gradient winds develop again by Friday. Dry conditions with above normal temperatures will continue through the upcoming week. A slight increase in temperatures, into the 101-106 degree range is anticipated across southeast CA and southwest AZ Wednesday and Thursday. MinRHs will mostly range from 15-25% across the western districts to 20-35% across eastern districts with fair to good overnight recovery (35- 60%) area-wide. No wetting rain expected through the next 7 days.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...Extreme Heat Watch from Wednesday morning through Thursday evening for AZZ532.

CA...Extreme Heat Watch from Wednesday morning through Thursday evening for CAZ566-567.