Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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681 FXUS65 KPSR 300515 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 1015 PM MST Mon Apr 29 2024 .Update...06Z Aviation Discussion && .SYNOPSIS... Warmer temperatures are anticipated over the next several days with highs rising into the low to mid 90s across the lower deserts. An upper level trough will pass through the Intermountain West mid-week resulting in breezy conditions across the region. Otherwise, dry conditions will prevail across the forecast area through at least this weekend. && .DISCUSSION... Benign weather conditions persist as quasi-zonal flow prevails across the Desert Southwest. Afternoon RAP analysis showed longwave troughing over the central CONUS while a shortwave trough is seen pushing into the Pacific Northwest. Locally, the quasi-zonal flow pattern will support continued dry westerly flow aloft, promoting mostly clear skies, while 500 mb heights continue to rise to around 575-578 dm today. Temperatures will respond accordingly as afternoon highs warm up several degrees above normal in the lower 90s. Widespread Minor HeatRisk will continue. Similar temperatures are in the forecast for tomorrow as the tranquil weather pattern persists before slightly cooling Wednesday. For the middle part of the week, a shortwave trough will swing through the Intermountain West while the core remains removed to the north from our area. However, we will see a tightening gradient as a result of this shortwave with an associated weak frontal boundary pushing into the region going into early Thursday. An increase in breezy conditions is expected Wednesday/Thursday with gusts upwards of 20-25 mph possible across much of the area. Temperatures for Wednesday and Thursday will see some slight cooling while remaining near to slightly above normal. Lower desert highs during this time will top out in the low 90s. Heading into this weekend, uncertainty remains high in regards to the potential for a deeper trough to affect the western CONUS with varying ensemble solutions with the pattern evolution. The GEFS continues to favor a deeper, amplified trough diving south along the West Coast this weekend before moving inland across California. This solution would favor a cooler, breezier weather pattern for our area. Meanwhile, the EPS, though the latest run of the ensemble has trended toward a deeper trough, keeps the greatest negative height anomalies further north across the Pacific Northwest. Depending on how this pattern evolves will dictate the amount of cooling and breeziness we see for the end of the week and into the beginning of next week. For now, NBM deterministic temperatures for the latter part of the week keep lower elevation highs in the low to mid 90s, while the interquartile range displays a continued large spread given the aforementioned uncertainties. Despite the uncertainty in temperatures, ensembles and deterministic models do agree that dry conditions are favored to persist through this weekend and into early next week and thus PoPs remain nil. && .AVIATION...Updated at 0515Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT and Southeast California/Southwest Arizona including KIPL and KBLH: No aviation concerns are expected across the region during the next TAF period. Winds will follow diurnal tendencies with speeds generally aob 10 kts at most terminals, except at BLH during the afternoon hours, where sustained speeds between 10-15 kts will be common with occasional gusts near 20 kts. Skies will be clear through the forecast window. && .FIRE WEATHER... Warm and dry conditions will persist this week and into this weekend with high temperatures around 3-5 degrees above normal each day. Winds will be light and follow typical upslope/downvalley patterns today and Tuesday before increased breeziness arrives Wednesday with gusts reaching the 20-25 mph range across much of the area. Windy conditions will also be possible across the western districts on Thursday as a dry cold front passes through the Colorado River Valley. Minimum relative humidity values will range from 8-15% each day. Moisture recovery will range from poor to fair each night, or around 25-50%. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Smith AVIATION...RW FIRE WEATHER...Smith/Salerno