textproduct: NWS Phoenix

KEY MESSAGES

- Near to slightly above normal temperatures will persist through the first half of the week before warming up towards the end of the week into next weekend as readings approach 110 degrees across portions of the region.

- Breezy conditions will continue through Tuesday, particularly across the Arizona higher terrain areas, resulting in elevated fire weather conditions.

- Seasonably dry conditions will persist through the next several days.

SHORT TERM /Today through Tuesday/

GOES mid-level WV imagery and RAP40 500mb analysis show the first troughing feature, that swept through the Pacific NW over the weekend, now well into Canada. Behind that initial system is another trough that has continued to keep broad troughing over the Western CONUS. However, even with this troughing in place, near normal height anomalies remain in place over the Desert SW as this second troughing feature will be contained well to the north. With that being said, afternoon high temperatures today will be between 98F- 102F across the western lower deserts and between 102F-105F across south central AZ. As the axis of this broad troughing sweeps up towards the NE H5 heights across the western lower deserts will quickly go from 583-585 dam today to between 588-591 dam across the entire lower deserts by Tuesday. As heights aloft continue to build, temperatures will increase in response, with afternoon highs tomorrow forecasted to be in the 103F-106F range across the entire lower desert. This will be around 2-3 degrees above normal for this time of year, and just the beginning for some warmer temperatures ahead.

Otherwise, afternoon breezy conditions will continue today across the lower Colorado River area, then shift into the eastern higher terrain Tuesday as the troughing feature passes to our north. During this time gusts between 20-25 mph will be common in each respective area and time. Additionally, with MinRH values continuing to hover near 10%, and very dry fuels, wide spread elevated fire weather conditions will persist today, with minor improvement starting Tuesday, however, caution should still be practiced.

LONG TERM /Wednesday through Sunday/

The synoptic pattern through the middle to latter half of the week will be transitioning as the longwave trough will lift east northeastward, allowing upper-level ridging to take hold across much of the western CONUS. As a result, upper-level heights will be on the rise with the latest guidance indicating 500 mb heights increasing to near 590dm by the end of the week into next weekend. This will allow for temperatures to warm up into an above normal category, potentially as high as 5-8 degrees above normal. This means that many of the lower desert communities will be approaching 110 degrees for afternoon highs as early as Friday and continuing into the weekend.

In addition to the increasing temperatures, guidance is also showing an increase in moisture by the end of the week and the weekend as southerly mid-level flow increases. The latest EPS and GEFS show PWATs increasing as high 1.0-1.2" across much of southern AZ. This increase in moisture would certainly be enough for some isolated convection to materialize across the AZ high terrain and will be something to monitor during the next several forecast cycles.

AVIATION

Updated at 1736Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation weather impacts expected through Tuesday under mostly clear skies. Winds will continue to mostly follow typical diurnal trends. A period of southerly crosswinds are expected at KPHX and KDVT midday through early afternoon before W-SW becomes more predominant. There is some uncertainty in whether the diurnal E winds will fully develop early Tuesday morning at all terminals, but speeds will be very light in the morning. This afternoon, wind speeds up to 8-13 kts with gusts up to 15-20 kts are expected.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns are expected during the next 24 hours. Winds will follow familiar diurnal trends at KIPL, while KBLH sees a more consistent S'rly component that will become breezy (20-25 kt gusts) during this afternoon. Other than some high clouds moving in later in the period, skies will be mostly clear.

FIRE WEATHER

Elevated fire weather conditions will persist through Tuesday as elevated breeziness combine with very low RH values. Afternoon breeziness will peak at 20-25 mph, highest across the AZ higher terrain areas. MinRHs will bottom out near 10% with poor overnight recoveries. Heading towards the middle to latter half of the work week, winds will be lighter, decreasing the overall fire weather threat. However, with MinRHs continuing to bottom out in the single digits to lower teens, even some marginal breeziness can create localized elevated fire weather conditions.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...None. CA...None.