Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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339 FXUS65 KPSR 221152 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 452 AM MST Sun Sep 22 2024 .UPDATE...Updated 12z Aviation Discussion. && .SYNOPSIS... Temperatures will steadily warm over the next few days reaching into an above normal category as strong high pressure builds over the region. Dry air will also remain entrenched over the area yielding little to no chance for precipitation through the entirety of the coming week. && .DISCUSSION... The taste of fall weather looks to be short-lived as the last of the low pressure systems that brought the cooler weather is quickly moving northeastward away from the region. Upper level troughing will still stick around for today, but heights aloft will quickly rise, as well as temperatures. Highs today are expected to reach into the normal range and this will be the last day for a while that sees temperatures near normal. A strong upper level ridge currently building off the northwest Pacific coast will shift inland over the Pacific Northwest on Monday and then shift east southeastward over all of the Interior West by Tuesday. This ridge will become our dominant weather feature across the Desert Southwest starting Tuesday and likely through the rest of the week. Ensemble mean H5 heights are seen rising to around 588dm over our region on Tuesday with very little fluctuations in the heights aloft through the rest of the week as this develops into an Omega Block pattern. Model runs over the past several days have been trending a few degrees warmer, especially later in the week with forecast highs now peaking right around record temperatures starting Wednesday in Phoenix to a few degrees shy of record in Yuma and El Centro. Forecast highs should begin to top 100 degrees over the majority of the lower deserts starting Monday with further warming through mid week. By Wednesday, highs are likely to top out between 103-107 degrees across the lower deserts with overnight lows creeping into the mid 70s on average. Expansive areas of Moderate HeatRisk are expected to develop by Wednesday with patchy areas of Major HeatRisk possibly on Thursday and Friday as NBM forecast highs peak between 104-108 degrees. By next weekend, model spread increases considerably with some members attempting to push the ridge farther to the east into the Southern Plains while allowing a near cut-off low to move into western portions of the Desert Southwest. Overall, a majority of members still keep the ridge mostly over our region through next weekend resulting in continued above normal temperatures. The influence of the potential cut-off low may end up bringing some slight cooling by next weekend and this is reflected in the NBM forecast highs dropping roughly five degrees over the western deserts to 2-3 degrees across the south-central Arizona lower deserts. No matter how the pattern evolves later this week into the weekend, dry conditions will continue to prevail. && .AVIATION...Updated at 1200Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation weather concerns are expected through the TAF period as dry, tranquil conditions prevail. Light, diurnal tendencies aob 8 kts will continue through the period with winds becoming light and variable at times during transition periods. Mostly clear skies will continue with mid clouds generally remaining across the high terrain north and east of Phoenix Sunday afternoon. Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns are expected through the next 24 hours. Light and variable winds less than 7 kts will be prevalent at both terminals through the period. Clear skies will persist. && .FIRE WEATHER... High pressure will gradually build over the region early this week resulting in warmer temperatures and dry conditions. Above normal temperatures with lower desert highs topping 100 degrees are expected starting Monday. MinRHs will fall from 10-15% over the lower deserts today to 8-12% starting Monday with higher terrain areas seeing up to 20%. Expect a more traditional diurnal wind pattern across the region over the next several days with little to no breeziness. Much of the same is expected through the rest of the week as the high pressure system keeps above normal temperatures and dry conditions over the region. && .CLIMATE... Record highs next week: Date Phoenix Yuma El Centro ---- ------- ---- --------- Sep 25 108 in 1989 112 in 1963 110 in 2015 Sep 26 108 in 1989 111 in 2010 110 in 2010 Sep 27 107 in 2009 111 in 1963 111 in 2009 Sep 28 108 in 1992 108 in 1994 109 in 2009 && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Kuhlman AVIATION...Young/Smith FIRE WEATHER...Kuhlman CLIMATE...18