textproduct: NWS Phoenix

UPDATE...Updated 00z Aviation Discussion

KEY MESSAGES

- Record breaking temperatures will continue through the end of the weekend, likely extending into the upcoming workweek.

- Extreme Heat Warnings remain in effect for lower desert areas through this evening.

- The unprecedented afternoon heat will be dangerous, especially with any strenuous or long-duration outdoor activities without proper hydration and taking breaks in the shade, or air conditioning.

SHORT TERM /TODAY THROUGH TUESDAY/

Mid-level water vapor imagery shows quasi zonal flow across much of the Western CONUS. This is in response to the core of the ridge being dislodged to the regions southeast, in conjunction to a few small shortwaves progressing through Canada, helping flatten out the upper level ridge. Additionally on 500 mb RAP analysis, a small shortwave trough can be seen just to our region's southwest, helping bring in some upper level moisture resulting in an increase in cloud coverage today, and lingering into Monday morning. Between lowering H5 heights, and a small increase in cloud coverage, afternoon highs today will generally be between 100F-102F with localized areas 1F-2F below 100F. Monday will be the "coolest" day with forecasted afternoon highs in the mid to upper 90s. Even though Monday will be the coolest day during this early season heatwave, record high temperatures will be broken, yet again.

Starting Monday night H5 heights look to restrengthen, with model guidance expecting heights to be between 587-590 dam by Tuesday evening. However, the thermal profile will lag behind, keeping Tusday's highs in the upper 90s, with localized areas breaking 100F. It will not be until the middle of the work week that temperatures will begin to float a few degrees above 100F once more.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

The longer term outlook does not offer much relief as the regional thermal profile catches up to the above-mentioned strengthening of the high, translating to a continuation of abnormally hot conditions for the latter portion of the month. H5 heights will rise to around 588-590dm, once again near climatological records, by Wednesday, ushering in the return of widespread triple digit heat for the lower deserts. This level of heat will continue to break daily records for many locations. In fact, Phoenix Sky Harbor has already set 4 consecutive daily records, and that is likely to extend to at least 11 by the end of the current forecast window. The only noticeable weather change is projected during the upcoming week is a compact trough traversing the Great Basin by as early as Wednesday as it rides around the periphery of the center of the high. However, the only expected change would be some breezy to locally windy conditions for parts of our forecast area. Even with some lower heights associated with the disturbance, temperatures will not be impacted as the ridge remains the dominant feature.

AVIATION

Updated at 2325Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation weather concerns expected throughout the TAF period. Winds will exhibit the typical diurnal tendencies with speeds aob 10 kts. SCT high cirrus cloud decks will persist through tonight with coverage decreasing to FEW throughout the day Monday.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns expected throughout the TAF period. At KIPL, winds through this evening will remain out of the west before shifting out of the southeast during the overnight period. At KBLH, winds will fluctuate between the south to south- southwest. Overall wind speeds will remain aob 10 kts, with the exception of some intermittent sundowner gusts near 20 kts this evening at KIPL. SCT high cirrus cloud decks will persist through this evening with coverage decreasing to FEW during the overnight period.

FIRE WEATHER

Record high temptress along with dry conditions will persist through the remainder of the weekend and into the upcoming week. MinRHs will generally range between 5-10%, with portions of the western districts being the exception during the front half of workweek. Increase in Gulf of California moisture will push MinRH values for these areas closer to 15-20% Monday and Tuesday. MaxRH values will follow a similar pattern with readings generally between 20-40% during much of the next seven days, as higher readings closer to 50-70% for some western districts locales. Winds will be generally light and follow diurnal trends through much of the foreast with typical afternoon upslope breeziness. More widespread and stronger gusts may come into play during the middle and latter portion of the week. With very dry air in place, any stronger winds would result in periods of elevated fire weather conditions.

CLIMATE

Daily record highs through the upcoming work week:

Date Phoenix Yuma El Centro ---- ------- ---- --------- 3/22 94 in 1990 98 in 2004 96 in 2004 3/23 93 in 1990 96 in 1990 93 in 1990 3/24 96 in 2025 97 in 2025 96 in 2025 3/25 99 in 2025 99 in 1896 99 in 2025 3/26 100 in 1988 99 in 1988 98 in 1988 3/27 98 in 1986 100 in 1986 99 in 1988

PSR WATCHES/WARNINGS/ADVISORIES

AZ...Extreme Heat Warning until 8 PM MST this evening for AZZ530>555- 559-561.

CA...Extreme Heat Warning until 8 PM PDT this evening for CAZ561>570.