Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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157 FXUS65 KPSR 271050 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 350 AM MST Fri Sep 27 2024 .Update...Updated Aviation Discussion && .SYNOPSIS... Excessive heat will continue through the first half of next week as an unseasonably strong high pressure system remains overhead. Lower desert communities will see daily high temperatures in the 106-115 degree range, with the hottest days of this stretch expected to be today and tomorrow. Temperatures look to cool off slightly by the end of next week, but will remain above normal. Dry conditions and mostly clear skies will also continue through next week. && .DISCUSSION... Unseasonably hot, record-breaking temperatures will continue to be the primary weather headline through the remainder of this week and into next week. Daily record highs have now been either tied or broken in Phoenix the past three days with yesterday`s high of 110 degrees breaking the previous record of 108 degrees. New record highs are likely to be set each day through the first part of next week as the intense heat persists. The strong ridge of high pressure responsible for the anomalous heat has shifted westward and is now centered over the international border with 500 mb heights across the area around 590 dm. Over the next couple of days, the repositioning and strengthening of the ridge will cause 500 mb heights to rise upwards of 591-593 dm and thus will further boost temperatures today and tomorrow with these days being the hottest in the forecast. By Saturday, temperatures will peak upwards of 15-20 degrees above normal for this time of year as forecast highs push upwards of 110-115 degrees. If Phoenix reaches 115 degrees Saturday as currently forecast, this would shatter the daily record of 108 degrees set in 1992 by 7 degrees. Additionally, this would of course be the latest 115+ degree temperature on record for Phoenix, with the current record for latest 115+ degree temperature set on September 5th earlier this month and in 2020. Going forward as temperatures remain well above normal into next week, widespread Major HeatRisk as well as some areas of Extreme HeatRisk will be in place for most lower desert locales. Thus, Excessive Heat Warnings are in effect for much of the forecast area through Tuesday. Temperatures will trend down closer to around 105-110 degrees Sunday and Monday as heights lower somewhat along with an uptick in moisture over the area. Nevertheless, temperatures will remain above normal with Widespread Major to areas of Extreme HeatRisk persisting. By Wednesday, NBM shows highs around 105-108 degrees, which will promote continued areas of Major HeatRisk and thus could lead to an extension of the Excessive Heat Warning if trends hold. Going through the mid to latter part of next week, global ensembles indicate heights gradually lowering over the Desert Southwest as the ridge weakens, allowing for temperatures to cool some. Despite the ridge weakening some as indicated by global ensembles, temperatures will continue to remain above normal as highs remain in the triple digits. Dry weather will continue to accompany the unseasonably warm temperatures with no chances for rain in the forecast. && .AVIATION...Updated at 1050Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation weather concerns under mostly clear skies are expected through the TAF period. Winds will follow typical diurnal trends with speeds aob 10 kts. Moments of variability may also occur during directional shifts. Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns under clear skies will exist through the TAF period. Winds will favor a west to northwest component at KIPL and west to north component at KBLH through the period with speeds aob 8 kts. There will likely be extended periods of variable and nearly calm winds as well. && .FIRE WEATHER... Hot, dry weather conditions will continue, with temperatures remaining well above normal into next week as a blocking pattern keeps strong high pressure over the region. Many places across the lower deserts will see high temperatures approach or exceed 110 degrees each day with Saturday expected to be the hottest day as temperatures top out upwards of 110-115 degrees. Min RHs will range around 7-15% each day, while Max RHs range around 20-30% for most places through the weekend. Winds will remain fairly light generally following diurnal wind patterns with the exception of some breezier conditions on Saturday. && .CLIMATE... Record highs this week: Date Phoenix Yuma El Centro ---- ------- ---- --------- Sep 27 107 in 2009 111 in 1963 111 in 2009 Sep 28 108 in 1992 108 in 1994 109 in 2009 Sep 29 107 in 2003 110 in 1980 110 in 1969 Sep 30 107 in 2010 109 in 2020 108 in 2020 Oct 1 107 in 2020 110 in 1980 110 in 1980 && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Excessive Heat Warning until 8 PM MST Tuesday for AZZ530-533-534- 537>544-546-548>551-553>555-559. Excessive Heat Warning from 10 AM this morning to 8 PM MST Tuesday for AZZ531-532-535-536. CA...Excessive Heat Warning until 8 PM PDT Tuesday for CAZ569. Excessive Heat Warning from 10 AM this morning to 8 PM PDT Tuesday for CAZ562-566-567-570. && $$ DISCUSSION...Smith AVIATION...Lojero/RW FIRE WEATHER...Smith CLIMATE...18