textproduct: NWS Phoenix

KEY MESSAGES

- Breezy to locally windy conditions are expected this weekend, particularly on Sunday across the foothills and higher terrain east of Phoenix, where Wind Advisories will be in effect.

- Below normal temperatures will continue today, then warm near to slightly above normal Sunday and continue gradually warming through the majority of the upcoming work week.

- Dry conditions will prevail across the region through at least the next week.

SHORT TERM /TODAY THROUGH SUNDAY/

Flow aloft has transitioned from NW/N yesterday to NE/E today as a Rex blocking pattern begins to take shape across the Western US. An upper level trough axis with strongly positive tilt at its southern extent is draped from off the Baja Peninsula up through the western Great Lakes region, while high pressure builds into the Interior West. Ensembles are in excellent agreement that a low will detach from this elongated upper level trough and settle near the Baja Peninsula tonight. In between this closed low and high pressure to the north, an easterly jet will form over the Desert Southwest tonight. Easterly flow will be unusually strong over Southern AZ with this setup, with NAEFS/ENS mean zonal winds near CFSR climatological maximum values early Sunday morning at the 850 mb (30-45 kts) and 700 mb (20-35 kts) levels. The easterly jet will reach peach intensity between 06-12 UTC, during the overnight hours, and so much of the populated valleys/lower elevations will be spared from the strongest winds, but once daytime heating commences Sunday, some of the higher momentum air will start mixing down to the surface. High terrain and prominent ridgetops to the east/southeast of Phoenix will likely see gusts up to 50-55 mph, with downstream foothills and adjacent lower deserts forecast to receive easterly winds of 20-30 mph with gusts up to 40-45 mph. Wind Advisories will be in effect for those areas from early Sunday morning through the early afternoon. Elsewhere across the lower deserts, daytime gusts to 20-35 mph will be common. The easterly jet will diminish over the course of the day, and so winds will decrease across the region to more seasonable levels by the evening.

Other than the unusually strong easterly winds tonight into Sunday, conditions will be dry, skies will be mostly clear, and temperatures will commence a warming trend as positive midlevel height anomalies begin to influence the region. A few isolated, sheltered valleys may see sub-freezing temperatures Sunday morning, with latest NBM still advertising near-freezing temperatures in the populated valleys of Southern Gila County. However, HREF probabilities for temperatures at or below 32F remain below 20%, even in those more cold-prone areas. Forecast highs Sunday are generally within a few degrees of daily normals, ranging from the middle 60s to around 70F across the lower deserts.

LONG TERM /MONDAY THROUGH FRIDAY/

Ensemble members are in good agreement that the rex blocking pattern will hold through at least the beginning of the upcoming workweek before the low finally breaks down during the latter half of the week. At the same time, the high pressure will maximize during this time, which is when we're forecasting the warmest temperatures of the upcoming week. Gradually warming temperatures are expected through the week. Afternoon high temperatures Monday and Tuesday are forecasted to be in the low to mid 70s across the lower deserts and in the 60s across the higher terrain. Then for the latter half of the week high temperatures warm into the mid to upper 70s to near 80 degrees across the lower deserts and in the mid 60s to low 70s across the higher terrain. Additionally morning lows will be on the rise, going from the 40s (30s) across the lower deserts (higher terrain areas) to start the workweek to the upper 40s to low 50s (low to mid 40s) to end the workweek. Dry conditions will also continue through this upcoming week.

AVIATION

Updated at 1730Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation concerns are expected during the TAF period. Winds will contain an E'rly component through Sunday morning with some occasional breeziness through during this afternoon. Enhanced flow just above the surface should create some marginal LLWS impacts, especially during the morning hours. TAF criteria is not anticipated to be met, or may only be reached in isolated instances, so mention of LLWS has been omitted at this time. Clear skies will prevail over the region.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation concerns are expected over the next 24 hours under clear skies. Winds at each terminal will favor a N/NNE component through this afternoon before backing to a NW/W'rly component by this evening. Speeds at KIPL should remain around 10 kts or less while KBLH can expected slightly higher readings around 10-15 kts.

FIRE WEATHER

Temperatures remain below normal today, followed by a warming trend back into an above normal category by the beginning of next week. Temperatures will go well above normal by the middle of this coming week. MinRH values have fallen into a 15-35% range and will remain in that range through this coming week, with overnight recoveries generally between 40-70%. Breezy to locally windy conditions will continue this weekend. The highest gusts will be across the eastern districts, especially ridgetops, where gusts in excess of 40 mph are likely tonight into Sunday. Winds will maintain a northeasterly to easterly prevailing direction through the weekend and possibly into early next week. Wind speeds will return to more seasonable levels next week.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...Wind Advisory from 2 AM to 2 PM MST Sunday for AZZ552-558.

Wind Advisory from 5 AM to 2 PM MST Sunday for AZZ547-555-557- 561-562.

CA...None.