textproduct: NWS Phoenix

KEY MESSAGES

- Temperatures will remain near normal through around Monday under clear to mostly clear skies.

- Strong high pressure will eventually build back into the region by the middle of next week pushing daytime highs to around or just above 110 degrees for a few days.

- Minor to Moderate Heat Risk is forecast through early next week before shifting to widespread Moderate to localized Major Heat Risk during the latter half of next week.

SHORT TERM /TODAY THROUGH SUNDAY/

Broad upper level troughing situated to our west and northwest has edged enough into our region to scour out any remaining moisture that helped to bring showers and thunderstorms during the first part of this week. Considerable dry air is in the process of working its way into the region and has already dropped surface dew points into the 30s and 40s. Humidities will continue to drop today into Saturday with afternoon readings falling to below 10% this weekend. Fortunately, the slow moving trough will keep heights aloft within the normal range over the next few days resulting in highs right around normal. Overnight lows will also be noticeably cooler due to the lower humidities and the lower heights. Most locations will see lows in the 70s through the weekend with more rural lower desert locations potentially dipping into the mid to upper 60s. The HeatRisk across the area will drop fully into the Minor category for this weekend.

LONG TERM /MONDAY THROUGH THURSDAY/

The upper level trough is forecast to break down and shift to our northeast starting early next week. As this occurs, the subtropical high centered just to our south will start to shift northward while also beginning to strengthen. Currently, model guidance favors the high center reaching southern Arizona by next Tuesday with H5 heights rising to around 595dm. This will allow for a warming trend to commence starting Monday with daytime highs as warm as 110 degrees by Tuesday.

Models also mostly suggest the high center setting up over or near southeast Arizona starting Tuesday and staying in that general vicinity through midweek. This positioning should allow for some modest Gulf of California moisture surges for a few days next week with forecast surface dew points gradually increasing back into the 40s to maybe the mid 50s. However, even with the modest increase in lower level moisture it will fall short of what would be needed for any convection to form. The close proximity of the high center and its strength will keep the subsidence quite strong next week, basically keeping a lid on any potential convection.

Guidance shows the ridge peaking at around 596-598dm next Wednesday and Thursday with daytime highs expected to break 110 degrees both days and some locations potentially reaching 115 degrees. Widespread Moderate HeatRisk will develop as early as Tuesday with a high probability of localized areas of Major HeatRisk for at least next Wednesday and Thursday. Guidance then favors another trough passing by to our north by next Friday or Saturday, likely dampening the ridge and starting a slight cooling trend.

AVIATION

Updated at 0900Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Winds will be the only weather forecast issue through Saturday morning under clear skies. Confidence is only moderate regarding the establishment of east winds this morning, followed by a brief period of a light southerly cross runway component. Some late afternoon/early evening gusts 15-20kt look probable, but may not be as pronounced or persistent as the past couple days before relaxing, and eventually turning back east late evening/overnight.

Southeast California/Southwest Arizona including KIPL and KBLH: Gusty winds will continue to be the main weather issue through Saturday morning under clear skies. Confidence is good that a W/SW component will be maintained at KIPL, however a few hours of late morning/early afternoon variability may occur. At KBLH, directions should oscillate between SE and SW. Late afternoon/evening gusts above 20 kt are likely with good confidence of periodic gusts near 30kt at KIPL this evening.

FIRE WEATHER

A pronounced drying trend will continue into the weekend, enough so to end any rain chances. Temperatures will fall within the normal range today through the weekend. Minimum humidity levels will drop into the single digits by Saturday and remain there at least through next Monday. Correspondingly, overnight recovery will fall into a poor to fair 20-40% range. Upslope afternoon gusts up to around 20 mph will be common over the next several days resulting in brief periods of elevated fire danger. By the middle of next week, temperatures will warm markedly with minimum humidity levels hovering around 10-15% and continued gusty winds yielding dangerous conditions for any ongoing wildfires.

PSR WATCHES/WARNINGS/ADVISORIES

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