textproduct: NWS Phoenix

UPDATE

12Z Aviation Discussion.

KEY MESSAGES

- Unseasonably warm temperatures will be seen today with highs well into the 80s, or around 15 degrees above normal.

- Breezy northeasterly to easterly winds are will develop today and reach their strongest Thursday morning with wind gusts between 20 and 30 mph across the lower deserts and upwards of 30 to 40 mph across the higher terrain.

- Above normal temperatures and overall dry weather should prevail through at least the weekend before a pattern change later next week brings cooler temperatures and potential precipitation chances.

SHORT TERM /TODAY THROUGH THURSDAY/

Today is shaping up to be quite warm across the area with a large ridge moving over the Western U.S. providing record high heights for the period across the Northwestern U.S. H5 heights of 582-584dm will be seen today across the Desert Southwest, or well into the 90th percentile of climatology. Most lower desert areas saw highs in the lower 80s yesterday, while today will bring even more optimal conditions for heating. The higher heights today and even warmer air aloft will more easily mix down to the surface today under increasing easterly winds and gusts of 20-25 mph in the afternoon. In addition to the slight boost (~1 degree or so) from the higher heights, downslope warming into the lower deserts may add another 2-3 degrees. Highs this afternoon are expected to reach between 82-85 degrees across the lower deserts with decent potential (25-40% probability) of overachieving by 1-2 degrees. Despite the NBM deterministic forecast high of 84 degrees for KPHX, we are quite confident it will be higher, potentially threatening the daily record of 86 degrees. A cut-off low has also taken shape west of Baja over the past 24-36 hours with guidance showing it starting to shift toward our region tonight into Thursday. As the low attempts to move into the ridge over our region, it will quickly tighten the pressure gradient tonight into Thursday allowing a easterly low-level jet to develop across southern and central Arizona. The strength of this low-level jet and how much of it will mix down to the surface is somewhat uncertain as there is a good deal of variance among the models. We could very well see a 30-45 kt low-level jet form tonight as indicated by the HREF, but a strong nocturnal inversion should limit what makes it to the surface. Unsheltered higher terrain areas and ridgetops may see wind gusts at times of 35-45 mph, but will be holding off on any Wind Advisories for now. Portions of the lower deserts should see winds pick up during the overnight hours with occasional gusts between 20-30 mph before more consistent breezy to windy conditions settle in after mixing later in the morning. The low-level jet will gradually weaken late morning into the early afternoon hours allowing winds to diminish throughout the afternoon.

A slug of high level moisture (15-25K feet) will also enter the region on Thursday, spreading from southwest to northeast. Fairly cloudy skies are likely to be seen across southeast California and southwest Arizona by early afternoon and by late afternoon for the rest of southern and central Arizona. The lowering heights from the incoming cut-off low and the increasing clouds will help to keep daytime highs in the upper 70s to around 80 degrees Thursday.

LONG TERM /FRIDAY THROUGH NEXT THURSDAY/

Model uncertainty remains a big part of the forecast for the weekend into next week. Models are confident the cut-off low moving into our region Thursday into Friday will quickly weaken and become an open wave before somewhat absorbing another weakening trough peeling off from the main flow off the coast of California. Models yesterday were hinting at the potential for a restrengthening of a new cut-off low forming from the two pieces of energy, but now they are backing off this potential solution. The latest runs do still show a brief closed low forming to our southwest by Saturday, but trends are now showing a much weaker system and progressing it farther to the south instead of coming back into or near our region. Any PoPs the NBM had introduced yesterday for Sunday and Monday are now mostly gone. Temperatures from Friday through Monday are expected to stay quite stable with highs mostly in the upper 70s to the lower 80s.

Forecast uncertainty increases even more for the rest of next week as the potential Pacific trough that may move into our region is now looking less impressive. The timing is still about the same with the trough moving through our region from the west around next Wednesday and Thursday, but ensembles have backed off on the QPF potential for now. Given this is still a week away, we should not put much stock in the guidance for another few days.

AVIATION

Updated at 1015Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns under mostly clear skies are expected through Wednesday. Easterly winds will continue throughout the entire TAF period with speeds generally aoa 10kts, primarily at KPHX and KIWA, after sunrise this morning. At KSDL and KDVT wind speeds will also increase by this morning, but will hover between 7-11 kts throughout the period. Gusts between 15-20 kts will be possible by the mid-afternoon hours. Mostly clear skies with increasing SCT-BKN cloud decks entering the region near midnight tonight.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns under mostly clear skies are expected throughout the forecast period. At KIPL, light westerly winds will continue before transitioning to N-NE by this afternoon. At KBLH, light NW winds will become more elevated out of the NE around the same time this afternoon.

FIRE WEATHER

Unseasonably warm temperatures and overall dry conditions will persist through the end of the workweek. Today will see highs well into the 80s with MinRHs of 10-15%. Winds will also increase today out of the east northeast with gusts of 20-25 mph possible. Winds will pick up further tonight through Thursday morning with wind gusts as high as 30-40 mph across portions of the eastern districts. Humidities will improve going into Thursday and then again Friday with MinRHs 15-20% Thursday and 20-25% Friday. Lighter winds with fairly stable humidities are expected for the weekend.

CLIMATE

Phoenix, AZ Daily Record High Temperatures.

2/4 86 (2025) 2/5 87 (1963)

PSR WATCHES/WARNINGS/ADVISORIES

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