textproduct: NWS Phoenix

UPDATE

Updated Aviation Discussion.

KEY MESSAGES

- Temperatures will gradually warm through the rest of the work week and the weekend, with afternoon highs topping out around 110 degrees across the lower deserts during the weekend.

- Breezy conditions will linger today, particularly across the Arizona higher terrain areas, maintaining an elevated fire danger threat.

- An increase in moisture by the end of the week and weekend will lead to isolated thunderstorm activity across the Arizona higher terrain areas.

SHORT TERM /Today through Thursday/

Early morning objective analysis depicts broad troughing in place across the western CONUS with a trough axis moving through the Desert Southwest. This troughing pattern will continue to result in enough of a pressure gradient to maintain elevated breeziness for today, particularly across the AZ higher terrain areas north and east of Phoenix, where peak afternoon/early evening gusts upwards of 25 mph are likely. The elevated breeziness combined with the very low RHs and dry fuels will maintain an elevated fire danger threat through today. With 500 mb heights ranging between 586-588dm, afternoon high temperatures today will top out between 102-106 degrees across the lower deserts, or about 2-3 above normal. As the overall longwave trough moves east-northeastward and high pressure aloft gradually builds overhead, heights aloft will increase close to 588dm Wednesday and Thursday, resulting in further warming as afternoon highs across the lower deserts top out in the mid to upper 100s.

LONG TERM /Friday through Monday/

Temperatures are forecast to increase even further heading into the upcoming weekend as the subtropical ridge, forecast to be centered near the Gulf Coast region, expands westward. With 500 mb heights forecast to increase to around 590dm, the latest NBM is depicting temperatures breaching the 110 degree mark for both Saturday and Sunday across the majority of the lower desert communities. Temperatures of these magnitudes will be enough to result in a high-end Moderate to localized Major HeatRisk across the region.

Model guidance continues to be consistent in showing moisture increasing across the region starting Friday and persisting throughout the weekend as the combination of the subtropical high located to the east and a weak upper-level low riding northward off the Baja Peninsula will induce a southerly flow. The latest EPS and GEFS mean show PWATs peaking at 1.1-1.4" across much of southern AZ and 0.7-1.0" across the higher terrain areas. Thus, enough moisture will be present to result in the development of higher terrain convective activity each day starting Friday and continuing through the weekend. Moisture looks to decrease by early next week as westerly flow settles over the region.

AVIATION

Updated at 1105Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns will exist through the TAF period under clear skies. Winds will generally follow diurnal tendencies, however, confidence is low on the exact wind directions at KPHX early this morning. Winds should shift out of the west by late morning, with occasional gusts into the middle to upper teens developing by mid afternoon and persisting into the early evening.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns are expected during the next 24 hours under clear skies. Daytime SE winds switching to SW/W this evening can be anticipated at KIPL. Occasional westerly gusts to around 20 kts will be possible at KIPL during the evening. Winds will favor S to SW at KBLH with high confidence in afternoon gusts peaking around 20 kts for a few hours. Outside those periods with gusts, wind speeds will generally remain light, AOB 10 kts.

FIRE WEATHER

Elevated fire weather conditions will continue today as elevated breeziness combine with very low RH values of near 10%. Afternoon breeziness will peak at 20-25 mph, particularly across the AZ higher terrain areas. Even though lighter winds are expected Wednesday, with MinRHs bottoming out in the single digits, even some marginal breeziness can create locally elevated fire weather conditions. MinRHs will increase closer to 15% towards the latter half of the week and upcoming weekend as moisture increases.

PSR WATCHES/WARNINGS/ADVISORIES

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