Sunrise 5:57 AM   Sunset 7:25 PM Moonrise 10:33 PM   Moonset 7:24 AM

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FXUS65 KPSR 260946 AFDPSR

Area Forecast Discussion National Weather Service Phoenix AZ 246 AM MST Fri Apr 26 2024

SYNOPSIS
A weather system moving across the Desert Southwest today will result in enhanced winds as well as chances for showers, mainly across the higher terrain areas north and east of Phoenix.
Any rainfall amounts will remain very light. Temperatures will continue to run below normal through Saturday before a strong warming trend ensues beginning on Sunday and continuing into early next week.

DISCUSSION
The shortwave trough that moved across the region yesterday, providing widespread breezy conditions as well as convective shower activity across the northern half of AZ, is now quickly progressing northeastward into the Central Plains. However, another trough over the northern Great Basin will quickly dive southeastward into the Desert Southwest later today. This trough is expected to be more potent compared to its predecessor.

The strong height falls associated with the approaching trough will cause another period of enhanced winds this afternoon and this evening across the majority of the region. The strongest winds are expected across the Yuma area, through most of Imperial County as well as across western portions of Joshua Tree National Park, where there is a high probability (>80%) of gusts exceeding 40 mph. As a result, a Wind Advisory remains in effect for these areas. The Wind Advisory that was in effect for portions of southern Gila County has been cancelled as the latest guidance has backed off on the maximum winds with the latest HRRR only showing a 10% chance of advisory level winds. Elsewhere, it will still be windy but not as strong with peak gusts during the afternoon and evening hours of upwards of 30-35 mph. The strong winds, especially in the western deserts, will be capable of producing areas of blowing dust, resulting in periodic reductions in visibilities.

The combination of better moisture flux with PWATs increasing to 0.5- 0.6" and increased forcing for ascent will be sufficient for the generation of shower activity later today, with most widespread potential mainly across the AZ High Country. Chances for rain, however, does still exist for south-central AZ, with the highest chances across the foothills and higher terrain to the north and east of Phoenix, where the latest NBM PoPs are now up to 40-60% for this evening through early Saturday morning. For the Phoenix area itself, PoPs are around 20-30%. There will be enough elevated instability for isolated thunderstorms with any of the showers, with the best chances across the higher terrain. Rainfall amounts for most part are expected to remain very light at less than a tenth of an inch, however, locally higher amounts cannot be ruled out, especially with any thunderstorm activity.

On Saturday, the trough will quickly move northeastward towards the central Rockies. There will still be some residual breeziness, but noticeably lighter compared to today as peak gusts area wide are expected to remain under 30 mph. Once the trough has fully cleared the Desert Southwest, the ensemble model guidance is in good agreement of low amplitude ridging developing overhead through next week with dry and tranquil conditions prevailing.

Under the influence of the troughing feature, high temperatures today and Saturday will remain below normal with highs across the lower deserts topping out in the low to mid 80s. Beginning on Sunday and continuing through early next week, as high pressure builds over the region, temperatures will be on a strong warming trend. High temperatures on Sunday will rise back up to near normal levels with readings in the mid to upper 80s before rising further into the low 90s on Monday and then into the mid to upper 90s by Tuesday. Not much change in temperatures is expected during the middle to latter half of the week with readings remaining steady state, in the mid to upper 90s, with a low chance (10-20%) that some areas, including Phoenix, reach 100 degrees.

AVIATION
Updated at 0510Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Periods of gusty afternoon/early evening winds will be the primary weather concern through Friday night under FEW-SCT midlevel decks.
Confidence is good wind directions will revert to light easterly after midnight, however directions should veer back to S/SW quickly by late Friday morning with gusts progressively strengthening during the afternoon. By late afternoon, gusts reaching a 25-30kt range should be common. Isold SHRA/TSRA across northern AZ should decay before reaching terminals Friday evening, however there is a remote chance (less than 20%) that a residual SHRA and outflow descends into the Phoenix metro.

Southeast California/Southwest Arizona including KIPL and KBLH: Strong, gusty W/SW winds will be the main weather concern through Friday evening under clear skies. Gusts should generally relax during the overnight hours, however stronger gusts should resume fairly quickly Friday afternoon. Widespread 20-30kt gusts should become common with KIPL likely experiencing gusts above 35kt at times late Friday afternoon/evening. As a result, lofted dust and regionally reduced slantwise visibilities are possible, though not specifically mentioned at the surface at any particular TAF site.

FIRE WEATHER
Another weather system will produce another period of strong winds, especially for this afternoon and evening. The strongest winds are expected across portions of the western districts, where gusts in excess of 40 mph are likely at times. Elsewhere, winds will lighter but still gusty, peaking at 30-35 mph. MinRHs will be high enough at between 20-30%, which will prevent any critical fire weather conditions from materializing. There will be a chance for showers this evening into early Saturday morning, mainly across the higher terrain areas north and east of Phoenix, however, the chances for wetting rains will be low at around 10%.
On Saturday, winds will trend downward with peak gusts of only 20-30 mph and MinRHs remaining above 15% area wide. Temperatures today and tomorrow will remain below normal with highs only topping out in the low to middle 80s across the lower deserts.
Thereafter, a significant warming trend takes place Sunday through early next week with little change in temperatures expected by the middle and latter half of the week. With the warming trend, RH values will trend downward with MinRHs bottoming out at around 10-15% starting on Monday. Winds through most of next week will be lighter with the typical afternoon upslope breeziness expected.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...Wind Advisory from 3 PM this afternoon to midnight MST tonight for AZZ532.

CA...Wind Advisory from noon today to midnight PDT tonight for CAZ560- 563-565>567.

Wind Advisory until midnight PDT tonight for CAZ562.

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