textproduct: NWS Phoenix

UPDATE...Updated 00z Aviation Discussion

KEY MESSAGES

- Unseasonably hot conditions will continue to challenge daily temperatures records through the rest of the week and into the weekend.

- These hot conditions may be dangerous, especially for any strenuous outdoor activities without proper hydration and frequent breaks in the shade, or air conditioning.

- Temperatures should finally begin to back away from record territory by the end of the weekend as the high shifts east and cloud cover and shower chances increase.

SHORT TERM /TODAY THROUGH FRIDAY/

On mid-level water vapor imagery strong ridging can still be seen lingering over the Western CONUS. The center of the ridge however is now well to our region's southeast, centered over SE AZ, SW NM, and Northern Mexico area. While the center of the ridge is not over our region, H5 heights are still quite high, with heights today between 857-590 dam. These heights remain in the max of NAEFS climatological percentile. In response, afternoon high temperatures across the lower deserts, today through Friday, will generally be between 98-102 degrees. These temperatures will continue to flirt with breaking record highs, and at the very least tying the previous records. Friday is expected to be the warmest day, before a pattern shift expected in the ladder half of the weekend.

An area of low pressure, currently sitting off the California Coast, will begin to move inland by late tonight / early Thursday morning. This area of low pressure will help facilitate breezier conditions, mostly along the Colorado River Valley and in SE CA. As the low progresses inland, it does look to weaken so winds are expected to be under advisory levels, but gusts between 15-25 mph will be common, with the higher range mostly confined to the ridge top areas. Calm conditions will resume by Thursday evening once this tiny disturbance passes through Northern Arizona into the Four corners region.

LONG TERM /SATURDAY THROUGH TUESDAY/

Heading into the weekend, a potent cold front will dive south across the Plains with a strong surface high building in behind it. This will result in noticeable enhancement of our regional pressure gradient, generating breezy to locally windy conditions for areas primarily east of the Colorado River. The highest gusts, which may exceed 35 mph, will be focused over the higher terrain areas east of the Phoenix metro area, but gusts 20-30 mph look possible (50-60%) for lower desert areas of South-Central and Southwestern Arizona. It appears likely (~80% chance) that some areas in the AZ high terrain will experience gusts that reach Wind Advisory criteria. However, with the limited spatial and temporal scope of advisory level winds, no products will be issued at this time. If future guidance expands the areas of 40+ mph gusts, then it would not be surprising to see an advisory issued in the coming days. Temperature wise, the front half of the weekend will pick up where the previous few days left off as readings in the upper 90s to around 100 degrees will be common once more.

The back half of the weekend may yield a very welcome change as the high begins to shift further east, with the axis of this feature becoming centered over the Front Range and the Central Plains. As the high shifts, it will impart southerly flow over the region which will tap into to sub-tropical moisture, setting up an almost quasi-monsoonal pattern over the Desert Southwest. Models continue to suggest PWATs increasing to 200-250% of normal across the majority of Arizona by Sunday. This flux will, at the very least, bring in considerable cloud cover over the region, helping to decrease insolation and lowering our temperatures, albeit just by a bit. Some showers and perhaps some thunderstorms cannot be ruled out in association with moisture at these levels, especially out in eastern Arizona and along our higher terrain areas of Gila County, but with temperatures remaining well-above normal, it would take a decent amount more moisture to achieve higher probabilities and greater coverage of any precipitation. Another factor that will likely inhibit any widespread showers and thunderstorms will be a lack of forcing. Synoptic lift will be missing so any vertical development would have to rely solely on orographic influence. As of now, PoPs for our eastern most areas stand at 20-25%, with less than 10% chances for the lower deserts. Any hope of rainfall for lower elevation areas will have to follow any outflow boundaries moving off the high terrain, but with where potential storms may initiate, and the expected storm motion, that appears to be an unlikely outcome at this point.

Rainfall Monday cannot be ruled out just yet as elevated moisture looks to remain over the region. However, it looks as if the start of next week may suffer from a similar setup as Sunday with decent moisture but not enough supporting lift. Even though there are some ensemble members that indicate better instability on Monday, the best chances for showers and thunderstorms is only around 20% out where enhanced terrain features can induce precipitation development. There are signs of an East Pacific trough approaching the West Coast toward the end of the forecast period. If this were to speed up at all and interact with lingering moisture, we could be talking about better rain chances in the coming days for the beginning of April.

AVIATION

Updated at 2330Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation weather concerns under generally clear skies can be expected throughout the TAF period. The overall wind pattern will continue to exhibit the typical diurnal tendencies with speeds generally aob 10 kts, with a few occasional afternoon/early evening gusts in the teens.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns with FEW to SCT high clouds tonight into Thursday morning can be expected throughout the TAF period. At KIPL, southeast winds will shift out of the west this evening before becoming more variable early Wednesday. At KBLH, winds will generally be out of the southwest through this evening before becoming more variable overnight tonight. Sustained speeds through this evening will generally range between 8-12 kts, with some gusts near 20 kts possible, especially at KIPL, this evening. Wind speeds will weaken during the overnight hours.

FIRE WEATHER

Record heat along with very dry conditions will continue through at least the start of the weekend. MinRH values will run generally around 5-10% over the next few afternoons before increasing closer to 10-20% starting Saturday. MaxRHs will follow a similar uptrend with readings close to 20-40% the next few mornings before rising through the weekend. Winds through the end of the workweek should be generally light and follow diurnal trends, although some marginal breeziness (gusts 15-25 mph) will be observed this afternoon and Thursday afternoon. Stronger winds (gusts 25-35 mph) enter the picture late Friday into Saturday mainly, for areas east of the Colorado River. Higher gusts upwards of 40+ mph will be likely (~80% chance) for portions of the Arizona high terrain, but should be confined to the highest ridgetops. With very dry air in place, marginal breezes will lead to periods of elevated fire weather conditions through Friday. Even with the enhanced winds for Saturday, RHs should come up enough to limit critical thresholds for being met, but continued elevated, to near critical, conditions can be expected.

CLIMATE

Daily record highs through this week:

Date Phoenix Yuma El Centro ---- ------- ---- --------- 3/25 99 in 2025 99 in 1896 99 in 2025 3/26 100 in 1988 99 in 1988 98 in 1988 3/27 98 in 1986 100 in 1986 99 in 1988 3/28 95 in 2015 98 in 2015 98 in 2015 3/29 97 in 2015 100 in 1897 97 in 1969

PSR WATCHES/WARNINGS/ADVISORIES

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