Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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608 FXUS65 KPSR 012321 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 421 PM MST Mon Dec 1 2025 .UPDATE...Updated 00z Aviation Discussion... && .KEY MESSAGES... - Dry and mostly tranquil conditions will exist through the next few days with some occasional breeziness for the Lower Colorado River Valley this afternoon. - Weak low pressure will dive across the Great Basin during the middle portion of the week potentially sparking some isolated shower activity over higher terrain areas of central and eastern Arizona. - Temperatures through the week will cool slightly, but will be generally steady, hovering around normal levels for this time of year. && .SHORT TERM /TODAY THROUGH TUESDAY/... The Desert Southwest currently finds itself caught between a positivley-tilted trough moving over the Southern Plains and a high amplitude ridge over the eastern Pacific. Even though heights aloft will be on the rise as the influence of the upper-level high pressure reaches out towards the Great Basin, cool, and dry northerly flow will keep temperatures generally in the upper 60s to lower 70s for lower desert areas. The somewhat enhanced pressure and thermal gradients will result in some occasional breeziness, with gusts around 25 mph being most common for portions of the Lower Colorado River Valley this afternoon. Persistent cool northerly to northwesterly flow aloft will help nudge temperatures down a degree or two for Tuesday. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Models continue to trend away from any impactful weather later this week with a second Pacific trough now expected to take a more northerly track. Ensembles are now in very good agreement the next system for later Wednesday and Thursday will be much like the first progressive system. Even compared to model runs yesterday, the system shows a more eastward and northerly track shift bringing the bulk of the energy across northeastern Arizona. Additionally, the fact the trajectory of the trough is completely inland and it is now likely to take a shallower track through our region moisture will be even more limited than previously expected. As are result, NBM PoPs have dropped dramatically since yesterday with PoPs dropping to below 10% for all of the western deserts and even the western half of the Phoenix metro. Depending on the exact track of the system, the Arizona high terrain may still see some light shower activity, but expected QPF amounts have fallen below 0.05". Temperatures should also dip a bit further with the passage of the trough with lower desert highs falling more into the mid to upper 60s for Thursday and Friday. Guidance also heavily favors a more expansive ridge setting up over the eastern Pacific later this week with a fairly likely chance of a portion of the ridge will edge into our region by the weekend. Although the ridge is shown to flatten out over the weekend, the weather pattern may support the ridge to rebuild again and push farther into our region during the first half of next week. We have high forecast confidence in dry conditions prevailing well into next week with temperatures eventually warming to above normal. && .AVIATION...Updated at 2320Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns under some passing high clouds can be expected throughout the TAF period. Wind speeds will generally be aob 7 kts throughout the period. North to northwest winds will be common at both KIPL and KBLH. At the Phoenix area terminals, generally light and variable winds will be common through early this evening before shifting out of the east later this evening. Confidence is increasing of winds temporarily shifting out of a light west to southwest direction at KPHX between the 09-13z time frame and thus a TEMPO group has been added to the latest TAF package to reflect this shift. Otherwise, a more typical diurnal wind pattern is expected to develop on Tuesday. && .FIRE WEATHER... Dry conditions will continue to prevail for the bulk of the region this week as two mostly dry weather systems pass near or through portions of the region. Today`s weak weather system will only bring breezy northerly winds across the Lower CO River Valley and slightly cooler temperatures. Another weather system for late Wednesday and Thursday may bring light precipitation chances, but mostly to higher terrain areas. Humidities this week will stay elevated with MinRHs mostly ranging between 25-35% much of the time, with good to very good overnight recoveries. Winds are expected to stay light across the eastern districts, while another round of breezy conditions will be possible across the western districts Wednesday and Thursday. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ SHORT TERM...RW LONG TERM...Kuhlman AVIATION...Lojero FIRE WEATHER...Kuhlman