Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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209 FXUS65 KPSR 071141 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 441 AM MST Sun Jul 7 2024 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... Extreme heat will continue across the region through the majority of this week as a strong high pressure remains overhead. Lower deserts will continue to see afternoon high temperatures in the 110-120 degree range with little to no overnight relief with overnight low temperatures ranging from the low 80s to low 90s. Some moisture will start to move back into the region by the middle to end of this week, leading to an increase in thunderstorm chances for southeastern Arizona and the Arizona high terrain. && .DISCUSSION... Upon analysis of upper- and mid-level water vapor satellite imagery this morning, the strong high pressure system is currently centered over California and western/southwestern Nevada. This high pressure system will slowly make its way eastward over the next week, however it`s strength will largely remain unchanged with 500 mb height fields expected to range between 594-597dm. This will result in relatively clear skies, with near zero storm activity for most of our region through the majority of this week. With the slow eastward propagation and very minimal change in the strength of the high pressure system, the extreme heat will continue through much, if not all, of this week. The lower deserts will see afternoon high temperatures in the 110-120 range with overnight/early morning low temperatures ranging from the low 80s to low 90s through at least Thursday. These temperatures will result in widespread Major HeatRisk and localized Extreme HeatRisk across the Arizona lower deserts and southeastern California. Due to this the Excessive Heat Warning has been extended through 8 PM MST/PDT Thursday, July 11. It is crucial to stay proactive in protecting yourself from these extreme temperatures as they can become deadly! Remember to stay hydrated; wear light, loose fitting clothes; and try to limit your time outdoors, especially during the hottest part of the day. The center of the high pressure system will move into western Arizona by the middle of this week. This will promote some moisture return into southern and eastern portions of Arizona, leading to afternoon and early evening isolated shower and storm chances across southeastern Arizona and higher terrain locations in eastern Arizona. Global ensembles continue to show PWAT values near 1" returning to portions of the Arizona lower deserts by Friday at the earliest. The increase in moisture will cause a slight cool down in temperatures over the Arizona lower deserts. There is still some uncertainty in the exact timing of the northward and westward extent of this increase in moisture. Due to this the Excessive Heat Warning may need to be extended through Friday, particularly for portions of southeastern California. By this coming weekend the high pressure system will make its way to the Four Corners Region. This will promote better moisture advection into our region, with global ensemble models showing PWATs rising above 1" across the region this coming weekend. This will lead to increased shower and storm chances, at least for the Arizona lower deserts. With the increased moisture, temperatures will also trend down below the excessive heat threshold. && .AVIATION...Updated at 1140Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Confidence in a full easterly wind shift at all TAF sites is low this morning, as a light west or light variability may prevail between 12-17Z at all but KIWA. SW to W winds will then increase by 17-18Z, with speeds up to 10-14 kts and gusting up to 20-25 kts this afternoon. More typical diurnal trends are expected tonight, with light winds becoming variable or east by or just after midnight. SKC will prevail. Southeast California/Southwest Arizona including KIPL and KBLH: Wind directions will generally favor SE at KIPL, aside from a few hour period of W this evening. S`rly directions will prevail at KBLH. Speeds will remain mostly aob 12 kt at KIPL. Speeds will be slightly stronger at KBLH, with sustained speeds in the low teens and the potential for some occasional gusts up to 20-25 kt. SKC will prevail. && .FIRE WEATHER... Hot and dry conditions continue through most of next week as high pressure remains overhead. Extreme temperatures continue with daily high temperatures generally between 110-120 degrees across the lower deserts and 95-110 degrees across the higher terrain. Daily MinRH values will range from 5-15% across the lower deserts and 10-20% across the Arizona higher terrain, with overnight recoveries generally in the 30-50% range. Winds will be fairly light and tend to follow their typical diurnal patterns, with some occasional gusts near 20 mph in the afternoons. This afternoon looks to be the breeziest this week, with afternoon wind gusts up around 20-30 mph, mainly across the eastern districts. The very hot and dry conditions will lead to an increased fire danger threat. && .CLIMATE... Record Highs Phoenix Yuma El Centro --------- ------- ----------- July 7 118 (2017) 118 (2017) 121 (2017) July 8 115 (1985) 118 (1958) 117 (1942) July 9 116 (1958) 119 (1958) 117 (1958) July 10 115 (1958) 118 (1959) 116 (2021) July 11 118 (1958) 118 (1958) 117 (1975) && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Excessive Heat Warning until 8 PM MST Thursday for AZZ530>555- 559. CA...Excessive Heat Warning until 8 PM PDT Thursday for CAZ560>570. && $$ DISCUSSION...Berislavich AVIATION...Benedict/Whittock FIRE WEATHER...Berislavich CLIMATE...Berislavich/Kuhlman