textproduct: NWS Phoenix

UPDATE

Updated 00Z Aviation Discussion.

KEY MESSAGES

- An overall broad scale troughing pattern will persist over the western U.S., resulting in temperatures remaining right around seasonal norms through the rest of this week.

- Dry conditions, with no threat of rain, and seasonal afternoon breezes are expected through the next 7 days.

SHORT TERM /TODAY THROUGH TUESDAY/

Latest GOES W infrared and visible satellite imagery indicates a broad trough of low pressure encompassing the western half of the U.S. with multiple embedded shortwaves rotating around the trough axis. The robust shortwave which was responsible for gusty winds, blowing dust, and critical fire weather in our region yesterday has since lifted into the S Rockies and is now bringing a round of severe weather to the Central Plains. As the trough axis passes over the Desert Southwest this afternoon, negative 500 mb height anomalies will continue to overspread the area, resulting in a mild afternoon across the lower deserts. Highs this afternoon are forecast to top out in the mid 80s across the lower deserts, with only 10-20% chances of reaching 90F in the main population centers including Phoenix and Yuma. Dry air will continue to filter into the region from the NW and cause sfc dewpoints to crash into the 20s and 30s across AZ and even into the single digits in southeast CA. This intrusion of dry air will result in cool overnight temperatures with lows falling into the mid 50s to low 60s across the lower deserts.

On Tuesday, a follow-on shortwave trough will dive through the Great Basin region, but will be much weaker than the one we experienced on Sunday. This shortwave will again result in enhanced breeziness along the Lower Colorado River valley where northerly gusts as high as 20-30 mph will develop early morning through midday. Increasing SW flow aloft over AZ will also result in breezy conditions, mainly over the higher terrain of northern and eastern AZ. Elsewhere across the lower deserts wind speeds will be much lighter, generally below 15 mph. Due to the positioning of the trough centered over the Great Basin, 500 mb hghts will not change much and thus high temperatures Tuesday afternoon will only warm by a few degrees into the mid 80s to lower 90s which is still below normal.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Through the rest of the week, global ensembles depict a lasting weak longwave trough pattern across the Desert South, with neutral height anomalies and no significant shortwaves rolling through the region. This will translate to rather seasonal weather conditions, but with a slow day-to-day warming trend. High temperatures are forecast to be near normal through the end of the work week - highs in the middle to upper 90s. Meanwhile morning lows are expected to be near to slightly below normal, largely due to dry air/low humidity and limited cloud cover. It is not until the weekend when odds of high temperatures reaching the 100 degree mark spikes back up to around 30-60%, as the longwave trough across the Desert Southwest breaks down. Conditions will remain dry through this weekend, with no threat of rain, and seasonal wind patterns are expected, with light winds through the overnight and morning hours and afternoon upslope breezes up to 15-25 mph.

AVIATION

Updated at 2330Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns expected throughout the TAF period. Westerly winds will prevail through this evening with some occasional gusts into the upper teens through sunset. Winds will resume their more typical diurnal pattern tonight through Tuesday with easterly winds expected during the overnight and early morning hours followed by a westerly shift by the late morning/early afternoon. A FEW-SCT clouds around 8 kft will clear out this evening making way for clear skies during the late evening/overnight. FEW high clouds will move in tomorrow afternoon and evening.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns under mostly clear skies can be expected throughout the TAF period. At KBLH, wind gusts upwards of 20-25 kts will subside over the next couple of hours. Then, west to northwest winds will prevail this evening, at both terminals, with speeds less than 10 kt. Winds will then go back northerly late tomorrow morning. Speeds will increase slightly at KIPL but remain around 10 kt. At KBLH wind gusts upwards of 20-25 kt are expected again tomorrow afternoon.

FIRE WEATHER

Seasonal temperatures with dry conditions will persist through the end of this week. Daily afternoon humidity values will bottom out around 5-15% each day with poor to fair overnight recoveries at 25-50%. After today seasonal wind patterns are expected through the rest of the week, with afternoon upslope breezes up to 15-25 mph and the only exception being another brief enhanced northerly wind down the Colorado River on Tuesday morning. There is no rain in the forecast through this weekend.

PSR WATCHES/WARNINGS/ADVISORIES

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