Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
223 FXUS65 KPSR 120533 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 1033 PM MST Tue Jun 11 2024 .UPDATE...Updated 06z Aviation Discussion. && .SYNOPSIS... High pressure will once again build over the Desert Southwest over the next few days, pushing temperatures back to near, and for some locations above, 110 degrees. In response, an Excessive Heat Warning has been posted for south-central Arizona until Thursday. A brief, relative cooldown will occur late in the week as an area of low pressure moves over our forecast area. && .DISCUSSION... Current objective analysis reveals the Desert Southwest under the influence of increasing heights aloft, while two areas of low pressure flank the region to the east and west. Atmospheric heights will continue their upward climb through the remainder of the day, pushing near 589-592 dam across our forecast area. This will result in an upward bump in temperatures, with high temperatures this afternoon across the lower deserts ranging between 106-111 degrees. Model guidance indicates further amplification of the upper-ridge through Wednesday while the cut-off low to our west continues to hover off the coast of northern Baja. Unseasonably high 500mb heights of 592-594 dam (near the 90th percentile of climatological normals) will promote another bump in temperatures for Wednesday afternoon. NBM MaxT forecasts have highs ranging between 109-113 degrees, with Phoenix flirting with a record high (113 degrees set in 2022). Widespread Moderate to locally Major HeatRisk will result from these unseasonably hot temperatures and those planning to be outside, or those who work outdoors, should take extra precautions during the next several days. In response to this period of heat, and Excessive Heat Warning has been posted for today through Thursday. The meandering area of low-pressure off the coast of Baja is projected to move onshore by late Thursday, providing the region with lowering heights aloft and increasing moisture levels. Relative cooling will take place as a result of the falling heights, with highs on Friday forecasted highs generally between 103-108 degrees across the lower deserts. The increasing moisture ahead of the low may yield some shower/thunderstorm activity across south- central Arizona, with the best chances (currently 20-25%) focused over high terrain locations north and east of Phoenix. Additionally, breezy conditions will increase late in the week, which combined with hot and dry weather will lead to enhanced fire weather conditions. Model clusters agree that once the aforementioned system ejects out of the Desert Southwest, ridging will once again build in its wake. Temperatures will likely near or exceed 110 degrees across much of the lower elevations by Saturday. Anyone with outdoor weekend plans should plan accordingly such as limiting time outdoors and maintaining adequate cooling and hydration. Uncertainty increases heading into the start of next week as a trough is shown pushing into the Pacific Northwest. However, the general consensus amongst models is that this troughing pattern will take hold across much of the western CONUS, with the main uncertainty being how deep this feature becomes. If the current forecast holds, a cooling trend can be expected regardless, with how much things cool off being dependent on how amplified this system becomes. && .AVIATION...Updated at 0535Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT; VFR conditions at all terminals under some passing high clouds can be expected through the TAF period. Winds will continue to exhibit diurnal tendencies with speeds generally remaining aob 10 kts, although some occasional afternoon/early evening gusts into the mid-teens cannot be ruled out. Winds will again have tendencies to have variability characteristics in direction and speeds during the transition periods, especially at KPHX. Southeast California/Southwest Arizona including KIPL and KBLH: VFR conditions at both terminals under some passing high clouds can be expected through the TAF period. At KIPL, winds will be out of the westerly direction into the overnight hours before light winds settle in into the morning hours. At KBLH, winds will generally be out of the south to southwest. Wind speeds will remain aob 10 kts through tomorrow morning, with afternoon winds generally around 10 kts, but cannot rule out sustains reaching up to 15 kts, with occasional gusts above 20 kts at both terminals in the later portions of the afternoon and into the evening hours tomorrow. && .FIRE WEATHER... Hot and seasonably dry conditions will continue to support a high fire danger across the area through the week. Temperatures will heat up over the next couple of days with afternoon highs across the lower deserts approaching or exceeding 110 degrees through Thursday. Winds will continue to generally favor diurnal tendencies with occasional afternoon breeziness of 20-25 mph expected across most of the region. MinRHs will range between 5-10% with overnight Max RHs between 15-35% expected. Going into the end of the work week, a weather system is expected to traverse the region and bring increasing breeziness, which will act to promote elevated fire weather conditions. Additionally, the weather system will bring a low chance (less than 10%) for dry thunder to the high terrain east of Phoenix. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Excessive Heat Warning until 8 PM MST Thursday for AZZ534- 537>555-559-560-562. CA...None. && $$ DISCUSSION...Smith/RW AVIATION...Young/95 FIRE WEATHER...Smith/Whittock