Sunrise 6:04 AM   Sunset 7:17 PM Moonrise 4:35 PM   Moonset 4:33 AM

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FXUS65 KPSR 201110 AFDPSR

Area Forecast Discussion National Weather Service Phoenix AZ 410 AM MST Sat Apr 20 2024

Update
12Z Aviation Discussion

SYNOPSIS
Unseasonably warm temperatures and mostly sunny skies will persist through early next week. Daily high temperatures, mostly in the mid nineties to as hot as the upper nineties are expected across the lower deserts, with the hottest days on Sunday and Monday. This will lead to widespread minor heat-related health risks. A slow moving weather system later next week is forecast to bring a gradual cooling trend through the end of the week, while also increasing winds across the region.

DISCUSSION
A weak upper level shortwave continues to track eastward across the Desert Southwest with the core of the disturbance bringing some high based virga showers to portions of central and eastern Arizona. By sunrise or shortly after sunrise, this activity will exit into New Mexico leaving behind clear skies for the rest of today. From tonight through Monday, the region will then fall under a slow moving shortwave ridge which will boost H5 heights back to around 580dm, while also boosting daytime highs into the mid to upper 90s for Sunday and Monday. Both of these days will bring the hottest temperatures the region has seen so far this spring with localized Moderate HeatRisk possible from Phoenix through southeast California. NBM probabilities of reaching 100 degrees largely remains unchanged at 5-20% affecting portions of Phoenix, Lower CO River Valley, and western Imperial Co.

By early next week, a Pacific upper level trough will start to approach the West Coast, but it is likely to stall out some by Tuesday as it becomes closed off. Over the past 24 hours, ensemble guidance has slowed up the initial push of the trough into our region with it mainly holding off until late Wednesday into Thursday. However, as the trough approaches the California coast by Tuesday, it should knock down our heights aloft over our region allowing for the beginning of a cooling trend. Forecast highs do drop back into the low to mid 90s on Tuesday and Wednesday before the bigger drop in temperatures is likely on Thursday once the trough eventually swings through our region. The influence of the incoming trough by the middle of next week will also bring an increase in winds over the area with afternoon wind gusts likely reaching to between 20-30 mph for several days.

Guidance then suggests a second follow-on shortwave trough will be possible by around next Friday or Saturday and this could drop daytime highs down to slightly below normal, or as low as the lower 80s. The first weather system during the middle of next week looks completely dry, but there may some slight chances for rain possible over higher terrain areas with the second system.

AVIATION
Updated at 1110Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

No aviation concerns are expected during the TAF period. Winds will be light (speeds aob 10 kts) and follow diurnal tendencies.
Other than a FEW high clouds passing over the region later in the forecast window, skies will be mostly clear.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation concerns are expected during the TAF period. Winds will be light (aob 10 kts) and follow diurnal tendencies. Clear skies will give way to a FEW to sometimes SCT high clouds by this evening.

FIRE WEATHER
Dry conditions and above normal temperatures will persist through early next week as lower desert highs top out each day mostly in the mid 90s. Winds this weekend will overall be light following diurnal daily trends with any afternoon breeziness in the mid teens. Min RHs will continue to fall into the 5-15% range each day, while overnight Max RHs mostly stay in a 25-45% range for most places. A cooling trend is then forecast for the latter half of next week eventually bringing temperatures back down to normal or below normal late next week. Breezy to locally windy conditions are also expected for much of next week with daily afternoon gusts commonly reaching to between 20-30 mph. Humidities are likely to stay quite low next week with daily MinRHs around 10% through the middle of the week before some improvement is forecast to around 20-25% late next week as temperatures cool down.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...None.
CA...Wind Advisory until 5 AM PDT early this morning for CAZ562.

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National City
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Sat -- 02:25 AM PDT     0.95 feet Low Tide
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