Marine Weather and Tide Forecast for Guadalupe, AZ

SYNOPSIS
Record-breaking heat will continue through at least Monday, with very little day-to-day changes in the weather pattern. An Excessive Heat Warning remains in effect through Monday as afternoon high temperatures reach upwards of 15 degrees above normal. A slight downtrend in temperatures is expected by the middle to end of next week as a weak disturbance moves in from the west, but temperatures will continue to remain above normal.

DISCUSSION
A hot, dry weekend is underway as a strong ridge of high pressure over the southwest CONUS continues to promote record-breaking excessive heat. As of noon, Phoenix Sky Harbor has reached 106 degrees, which breaks the daily record high and now brings Phoenix up to 12 consecutive days of temperatures tying or breaking daily record highs. In addition to the record highs, Phoenix has now had 8 consecutive days of record warm lows. Record-breaking temperatures will continue through at least Monday as temperatures climb upwards of ~15 degrees above normal. Anyone with weekend plans should take the necessary heat safety measures to protect against the heat.

The ridge of high pressure over the Desert Southwest has strengthened with RAP analysis showing 500 mb heights upwards of 592- 593 dm over the region. As a result, temperatures for many lower desert locales will top out around 110 degrees through Monday, which will shatter daily record highs across our area. Temperatures of this magnitude for this time of year will continue to promote widespread Major to areas of Extreme HeatRisk and thus an Excessive Heat Warning remains in effect for much of the lower deserts through Monday evening. For some context in regards to just how abnormal it is to see temperatures of this magnitude in October, the record latest 110 degree temperature occurrence in Phoenix prior to this year was September 19, 2010, while the average (1991-2020) last 110 degree temperature occurrence is August 26th. Meanwhile, the average last 100 degree temperature occurrence is today, October 5th.
Temperatures early next week will gradually trend downward, though the NBM keeps temperatures hot enough into Tuesday to support some continued areas of Major HeatRisk. Thus, the Excessive Heat Warning could be extended through Tuesday for parts of the area in future forecast updates.

A weak shortwave trough will approach the southern coast of California going into the middle part of next week, leading to gradual weak height falls over the region. Additionally, the weak disturbance will also import some mid and upper level moisture, which could be enough to promote shower development across parts of the Arizona high terrain but otherwise will lead to an increase in cloud cover over the region. Temperatures will respond to the weak shortwave by gradually trending downward during the mid to latter part of next week, though still remaining well above seasonal normals as forecast highs remain in the 100-105 degrees for most lower desert areas. Uncertainty increases heading into next weekend as guidance suggest a deeper eastern Pacific trough will propagate into the western CONUS. At this point in the forecast, it's no surprise to see a lot of uncertainty showing up in the global ensemble clusters in regards to the evolution of this trough.
Something to watch as a deeper trough solution into the western CONUS could finally push temperatures down below 100 degrees for our area.

AVIATION
Updated at 2315Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns under mostly clear skies can be expected through the TAF period. Overall wind pattern will continue to exhibit the typical diurnal tendencies with light speeds under 7 kts. There will likely be extended periods of very light/calm and variable winds, especially during the periods of diurnal transition.

FIRE WEATHER
Dry and abnormally hot conditions will persist through early next week, with lower desert highs ranging between 104-112 each afternoon. There will be little to no day-to-day change in the weather through Monday with the continued heat, mostly clear skies, and light winds. MinRH values will range between 5-15% each afternoon, while MaxRH readings are expected to be between 20-35%, with locally higher values in Yuma and Imperial Counties. There will be a very slight increase in moisture beginning around Tuesday that may keep MinRH values from falling into the single digits, but most areas will still see 10-15% readings in the afternoon through the end of next week. There will also be potential for some regional rain showers with the moisture increase, but at this time the chances are very low (5% or less) across the lower deserts and CWR is near zero. Winds will follow familiar diurnal trends, with occasional afternoon gusts near 15-25 mph.

CLIMATE

Record highs through next Wednesday:

Date Phoenix Yuma El Centro ---- ------- ---- --------- Oct 5 105 in 2020 108 in 1917 106 in 2020 Oct 6 105 in 1917 108 in 1980 106 in 1964 Oct 7 104 in 1991 108 in 1987 105 in 1991 Oct 8 104 in 1987 107 in 1996 106 in 1996 Oct 9 103 in 1996 106 in 1996 104 in 1996

PSR WATCHES/WARNINGS/ADVISORIES
AZ...Excessive Heat Warning until 8 PM MST Monday for AZZ530>544-546- 548>551-553>555-559.

CA...Excessive Heat Warning until 8 PM PDT Monday for CAZ562-566-567- 569-570.