Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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376 FXUS65 KPSR 051759 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 1059 AM MST Wed Jun 5 2024 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... High pressure building over the region through Thursday will push temperatures higher resulting in the hottest temperatures of the year through the rest of the week. An Excessive Heat Warning is in effect across all of the lower deserts today through Friday with some spots at risk of breaking daily temperature records. A slight cooling trend will then begin on Saturday with more cloud cover, but temperatures are expected to remain above normal. && .DISCUSSION... Over the past 24 hours, the residual higher level moisture from the atmospheric river that hit the Pacific Northwest earlier this week has passed through the Desert Southwest. The higher clouds from this moisture have all since dissipated and/or pushed south into Mexico leaving clear skies across our region. Current water vapor imagery shows modestly drier air working in from the north associated with the building upper level ridge now overtaking much of the Southwestern U.S. and the Great Basin. As the ridge fully moves over our region later today, it will push H5 heights from 585dm yesterday to around 592dm which would fall within the 90th percentile of climatology across the southern half of the region to as high as the 97th percentile across northern Arizona and much of the Great Basin. The ridge is forecast to sit over the Southwestern U.S. through Friday creating a fairly strong heat dome for early June and pushing surface temperature anomalies to around 10 degrees above normal. After a week of temperatures running slightly above normal with highs between 100-105 degrees across the lower deserts, today will mark a noticeable jump in temperatures as highs reach to between 105-110 degrees. The full force of the heat dome will then realized on Thursday and likely into Friday as NBM forecast highs top out between 109-114 degrees. It`s likely that Phoenix will break the daily record high temperature on Thursday of 111 degrees, while Yuma and El Centro fall a few degrees shy of their daily records. An Excessive Heat Warning goes into effect starting late this morning and currently lasts through early Friday evening. While the upper level ridge dominates the region over the next 2-3 days, a weak cut-off low will be spinning off the coast of Baja. The placement of the low to our southwest and the high center over New Mexico starting Thursday will result in weak southeasterly flow into Arizona and some slight moisture advection into the state. There should be just enough moisture for isolated afternoon convective showers and maybe a few weak thunderstorms starting Thursday from the White Mtns northwestward along the Mogollon Rim. Moisture levels are shown to be quite limited and these areas should be the extent of the rain chances through the weekend. A southerly steering flow should keep any of this limited convective activity well north and east of the Phoenix area with PoPs only at around 10-15% across eastern Gila Co. By Saturday, models generally agree the cut-off low will move up the Gulf of California reaching northern Mexico later in the day. This should bring increasing clouds to our area throughout the day on Saturday, while the high pressure ridge weakens and starts to move east of the region. As a result, forecast highs Saturday drop back to between 106-110 degrees. The lowering heights aloft and noticeable cloud cover should then persist through Sunday with highs lower further to between 104-108 degrees, or back to around 5 degrees above normal. The weather pattern during the first half of next week may support another cut-off low forming off the coast of California, but this next one could be stronger. The positioning of this low and how it will impact our region next week is still fairly uncertain. If the low stays well to our west, as the ensemble means currently favor, it would likely present another warming trend as ridging would be favored to build back over Arizona and New Mexico. For now, NBM forecast temperatures show a fairly large spread going into the middle of next week, but the overall trend should be hotter with more 110 degree temperatures likely coming as early as next Tuesday. && .AVIATION...Updated at 1758Z. South-Central Arizona including KPHX, KIWA, KSDL, KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH: Winds will follow typical early Summer diurnal tendencies for at all terminals, with speeds generally aob 10 kt. Occasional afternoon gusts up to 15-20 kts can be anticipated in the Phoenix area. SKC will prevail through this afternoon. However, there may be FEW cumulus near the Phoenix metro this afternoon and evening, based around 15-16K ft. FEW to SCT high cirrus will also spread over the Phoenix area Thursday morning. && .FIRE WEATHER... Hotter temperatures are expected over the next few days, while seasonably dry conditions prevail. Lower desert highs are expected to reach up to 110F today and in into the 110-115F range for Thursday and Friday. Afternoon minimum RHs of around 10% will continue through the end of the week, while overnight recoveries will mainly range from 20-40%. Winds will remain fairly light across all districts with typical diurnal tendencies and afternoon gusts up to around 20 mph. A weak weather system is then expected to move through the region Saturday into Sunday allowing temperatures to start to lower, but will remain above normal. Winds will also increase a bit which could push afternoon gusts up to 25 mph in some locations. && .CLIMATE... Record high temperatures: Date Phoenix Yuma El Centro ---- ------- ---- --------- June 5 113 in 2016 115 in 1957 114 in 2016 June 6 111 in 2016 114 in 1928 113 in 2002 June 7 115 in 1985 116 in 1985 113 in 1985 && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Excessive Heat Warning until 8 PM MST Friday for AZZ530>556- 559>562. CA...Excessive Heat Warning until 8 PM PDT Friday for CAZ561-563-566- 567-569-570. && $$ DISCUSSION...Kuhlman AVIATION...Benedict FIRE WEATHER...Kuhlman CLIMATE...18