Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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316 FXUS65 KPSR 282151 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 251 PM MST Sun Apr 28 2024 .SYNOPSIS... Temperatures will return to seasonal levels today over the forecast area. An overall dry and benign weather pattern will set up across the Desert Southwest this week with highs rising slightly above normal starting tomorrow. Breezier conditions will be possible during the middle part of the week. Otherwise, warm and dry conditions with no precipitation is anticipated through the week. && .DISCUSSION... Another quiet weekend afternoon is ongoing across the forecast area as a tranquil pattern sets up for the start of the new week. Currently, objective analysis showed the southwest CONUS under the influence of broad cyclonic flow while an upper low is currently centered over Nebraska/South Dakota. Locally in Arizona, a weak vort max is pushing across the state, aiding in the development of an expansive cloud field over the northern AZ high terrain/orographic features with no sensible impacts across the lower elevations. Temperatures today will warm back up to near normal readings as heights rise in response to a quasi-zonal flow pattern that will prevail for the start of the new workweek. Temperatures this afternoon will be ~5-7 degrees warmer than yesterday as highs top out in the upper 80s to near 90 degrees across the lower deserts. As mentioned before, quasi-zonal flow will prevail for the start of the new workweek, pushing 500 mb heights to around 575-578 dm through the first part of the week. Temperatures will respond by rising near to slightly above normal as highs climb into the lower 90s starting tomorrow. Uncertainty increases heading into the mid to latter half of this week in regards to the evolution of a trough that will move into the northwest CONUS early in the week. Ensemble cluster analysis reveal the bulk of global members favor a solution where greater negative height anomalies remain to our north, while a minority of members (predominantly comprised of GEFS members) show troughing deepening further south closer to our area. The latter solution would favor a cooler, breezier pattern for our area. As of now, NBM deterministic highs remain in the low to mid 90s through the week before increasing into the mid to upper 90s for the weekend, though larger temperature spread is seen in the interquartile range due to the aforementioned uncertainties. Despite these uncertainties, ensembles agree that dry conditions are favored to persist through the week. && .AVIATION...Updated at 1737Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT and Southeast California/Southwest Arizona including KIPL and KBLH: Light winds, generally aob 7 kts, following typical diurnal directional patterns will prevail at all terminals. Extended periods of calm to light and variable winds are anticipated as well. SKC skies will prevail with no VIS impacts. && .FIRE WEATHER... A warming trend will continue through the first part of this week as afternoon temperatures rise near to slightly above normal in the low to mid 90s across the lower deserts. Along with the warmer temperatures, it will be consequently drier each afternoon with minimum relative humidity values bottoming out around 8-15% over the next several days. Overnight Max RHs will initially be in the 30-50% for the first part of the week before gradually decreasing during the latter half of the week. Lighter winds will follow typical upslope/downvalley patterns through the first part of this week. Winds are expected to stay below 15-20 mph through Tuesday, however there is potential for some increased breeziness toward the middle to latter half of this week as a dry weather system passes north of the area. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Smith AVIATION...Benedict FIRE WEATHER...Smith/Salerno