Sunrise 5:32 AM   Sunset 7:57 PM Moonrise 1:14 PM   Moonset 1:04 AM

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FXUS65 KPSR 141228 AFDPSR

Area Forecast Discussion National Weather Service Phoenix AZ 528 AM MST Fri Jun 14 2024

UPDATE
Updated 12z Aviation Discussion.

SYNOPSIS
Very hot and dry conditions will persist through the weekend, with Excessive Heat Warnings in effect for various parts of the region through Sunday. The hottest day is expected to be Saturday with highs topping 110 degrees over the majority of the lower deserts. Temperatures will eventually cool back to normal levels during by the early part of next week before heating back up late next week.

DISCUSSION
The upper level low that brought considerable cloudiness and some light shower activity yesterday is currently centered just northwest of Phoenix. Dry air has swept in from the southwest since the evening hours with any residual clouds and showers now confined to the north and east of Phoenix. By sunrise, skies should be clear across all but far eastern Arizona. The low is forecast to become an open wave before exiting into New Mexico this afternoon as strong ridging begins to quickly build in from the southwest. By late afternoon, forecast H5 heights reach to around 590-591dm before peaking at 592-593dm tonight across southern Arizona and southeast California.

Given the increasing heights today and sunny skies, temperatures will heat up quickly with highs topping out between 109-112 degrees across the western deserts to 105-109 degrees across the south-central Arizona lower deserts. The hottest temperatures are still expected to occur on Saturday with highs between 110-114 degrees across the lower deserts and areas of Major HeatRisk.
Excessive Heat Warnings are in place for portions of southeast California today and Saturday and through Sunday for much of south-central Arizona. Starting Sunday, lowering heights aloft from an incoming Pacific trough moving through the Pacific Northwest will begin to lower temperatures, but some locations in the Phoenix area could still top 110 degrees.

Relief from the excessive heat is expected by Monday as H5 heights lower down to 582-585dm and highs drop well below 110 degrees.
Near normal temperatures are expected Monday through Wednesday as the region stays under the influence of the Pacific trough, despite the core of the trough only brushing across the northern portion of the Great Basin. Unfortunately the "cooler" but still near normal temperatures will be short-lived as the unseasonably strong ridge that impacts the eastern U.S. early next week is forecast to shift westward starting next Wednesday. Temperatures should quickly heat up starting next Thursday with highs likely topping 110 degrees over the south-central Arizona lower deserts.
Ensembles generally agree the core of the ridge with H5 heights around 592-594dm is likely to move back over the Desert Southwest by next Friday into the following weekend. The latest NBM temperatures show highs peaking during this time between 112-116 degrees, or roughly 8-10 degrees above normal. Granted this is still a week out, but models are fairly certain we will see another excessive heat event later next week. Guidance is also showing the flow turning out of the east southeast later next week potentially allowing for some modest moisture advection into Arizona. For now, forecast ensemble mean PWATs increase to around or just over 1" by next weekend. This could present our first real chance for some monsoon activity in Arizona, albeit still minimal.

AVIATION
Updated at 1220Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation impacts are expected for the valid forecast period.
Winds will generally favor light diurnal trends for today. Winds have shifted out of the southeast over the last hour or so, but this recent development is expected to be short-lived this morning. Winds will predominantly become light and variable through the morning hours, with exception of KIWA, which may see a more definitive westerly shift late this morning. Focusing on KPHX, light and variable winds could extend past 00z, before a W-NW component develops through the evening and early overnight hours. Otherwise, expect the westerly winds to lighten late this evening and into the overnight period, with either light and variable or a southeasterly component winds to develop. Otherwise, clear skies are expected through the period.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation impacts are expected for the valid forecast period.
Winds at KIPL will favor a westerly component aob 10 kt through the TAF period. At KBLH, light and variable winds will go southeasterly this afternoon and then back southwesterly tonight.
Wind speeds will be aob 10 kt through the TAF period. Skies will be clear through the period as well.

FIRE WEATHER
Hot and dry conditions will continue to bring elevated fire danger to much of the region into next week. Lower desert high temperatures will approach 110 degrees today and likely exceed 110 degrees on Saturday. After light winds today, winds will become breezy over the weekend with gusts oftentimes reaching 20-25 mph during the afternoon and early evening hours. MinRH values will range between 5-10%, while poor overnight recoveries can be expected with MaxRHs only reaching towards 15-35%. A gradual cool down will bring temperatures back to near normal early next week with breezy conditions persisting through Tuesday.
High pressure is then expected to build back over the region later next week leading to another period of very hot temperatures while RHs stay quite low. There are signs of some moisture seeping into the eastern half of Arizona by next weekend and this could bring some chances for showers and thunderstorms over higher terrain areas.

PSR WATCHES/WARNINGS/ADVISORIES
AZ...Excessive Heat Warning until 8 PM MST Sunday for AZZ534-537>555- 559-560-562.

CA...Excessive Heat Warning from 10 AM this morning to 8 PM PDT Saturday for CAZ562-563-566-567-570.

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San Clemente
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Fri -- 03:29 AM PDT     3.40 feet High Tide
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Fri -- 10:20 AM PDT     0.98 feet Low Tide
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