textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- A low pressure system and lingering showers will exit the region today with a brief period of cooler temperatures.

- High pressure will quickly build into the region the remainder of the week leading to dry weather and record warmth possible by the weekend.

SHORT TERM /Today through Thursday/

A well defined cutoff low continues its slow progression eastward into cntrl/nrn Sonora with several vorticity centers rotating about the larger cyclonic gyre. Upper level divergence fields remain maximized over the forecast area on the northern edge of the cold core with modest theta-e advection importing moisture northward. Several bands of showers will continue to pivot into southern Gila County through the morning before more defined subsidence spreads into the area by late afternoon in response to the cutoff finally accelerating into far west Texas. Thereafter, pronounced height rises will quickly build into the SW Conus as broad subtropical ridging becomes established over the East Pacific. There is excellent forecast confidence H5 heights gradually climb near 585dm resulting in sfc temperatures nearly 15F above normal Thursday.

LONG TERM /Friday through Monday/

Forecast confidence remains excellent through the weekend with resounding ensemble agreement depicting stagnant longwave features settling over the Conus. With trough amplification over the eastern Conus, strong East Pacific ridging will envelop the Southwest with H5 heights oscillating between 582-588dm. Ensemble guidance spread remains extremely narrow and reflects anomalous tropospheric height/thermal measures near the maximum of mid March climatology. High temperatures 20F above normal will become common by the end of the week resulting in widespread minor HeatRisk while also setting daily records (see Climate section). It's becoming inevitable that some the warmer, lower desert communities will experience the first 100F of the season early next week as the NBM 50th percentiles now covers this threshold. Virtually all ensemble members indicate even warmer weather materializing by the middle of next week as H5 heights likely eclipse 590dm. The ensemble guidance envelop is solidly above the 100F threshold for all lower desert communities portending a prolonged period of record setting, and potentially unprecedented warmth.

AVIATION

Updated at 1100Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation concerns are expected during the TAF forecast as -SHRA activity clears the region. Winds will follow diurnal trends with extended periods of VRB through the early daylight hours and an eariler-than-usual establishment of westerly directions. A few gusts may observed with those late morning west winds, but any breezes should be mostly in the mid to upper teens. Lower CIGs around 6-8k ft will gradually scatter out after sunrise, with mostly clear skies taking over by the evening hours.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation concerns are expected during the next 24 hours. Winds will be generally light aob 10 kts at both terminals with some windows of VRB to calm conditions. Outside of these light and variable periods, KIPL will see winds flip between east and west, while KBLH can expected a generally S/SW component throughout the forecast. Skies will be generally clear.

FIRE WEATHER

Dry weather with unusually warm temperatures and low humidities will return during the latter half of the week with record setting warmth likely by the weekend. Minimum humidity levels in a 25-50% range this afternoon will deteriorate significantly closer to a 7-15% range late in the week. Correspondingly, good to excellent overnight recovery of 60-90% will retreat into a 15-40% poor to fair category. Winds will be fairly light with only modest afternoon upslope gustiness limiting a greater fire weather danger.

PSR WATCHES/WARNINGS/ADVISORIES

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