textproduct: NWS Phoenix

UPDATE

Updated 00Z Aviation Discussion.

KEY MESSAGES

- High pressure building over the region will lead to rapid warming through the rest of the weekend, with afternoon highs pushing 5 to 10 degrees above normal by Sunday.

- Dry conditions along with well-above normal temperatures will prevail throughout all of next week, with afternoon highs by the second half of next week approaching the upper 80s to lower 90s and near daily records.

SHORT TERM /TODAY THROUGH SUNDAY/

After a very chilly start to the day that saw many areas dip down between the mid 30s and low 40s (with some areas near freezing) for early morning lows, afternoon high temperatures will rebound nicely with many of the lower desert areas expected to reach the upper 60s to low 70s. This rebounding in temperatures compared to the last couple of days is due to a building ridge of high pressure over the interior western CONUS, which is resulting building heights aloft with 500 mb height fields rising close to 580dam by late this evening. An expansive area of mid to high-level clouds will move into the region from the subtropical Pacific late this afternoon and persist through tonight, causing overnight temperatures to be significantly warmer compared to last night on the order of 5-10 degrees warmer. Therefore, most locations will see early morning lows on Sunday bottoming out in the 40s compared to the widespread 30s that was observed early this morning, with central Phoenix bottoming out to near 50 degrees.

Heading into Sunday, the aforementioned ridge of high pressure will strengthen even more with 500 mb height fields across the region rising to between 582-584dam. This strengthening of the high pressure will cause afternoon high temperatures to soar an additional 10 degrees, with readings in the upper 70s to low 80s across the lower deserts. With temperatures approaching 80 degrees, this will also present a Minor HeatRisk for portions of the region, therefore if partaking in outdoor activities for a extended period during the afternoon hours, make sure to frequently hydrate and take breaks in the shade. An easterly gradient setting up across eastern AZ in response to strong surface high pressure to the northeast will also result in some breezy conditions, especially from the mid/late morning hours into the early afternoon hours across south-central AZ as peak gusts could potentially reach 15-25 mph with some locally higher gusts closer to 30 mph across the higher terrain areas east of Phoenix.

LONG TERM /MONDAY THROUGH FRIDAY/

The warming trend will not stop with this weekend. The synoptic and large-scale pattern favors ridging persisting over the Desert Southwest, with H5 heights staying around 582-585dam through the end of the month. Under this riding pattern, persistent southwesterly flow will lead to continued warming through the coming week, with 850mb temperatures forecast to reach up to 17-19C by mid to late week. Temperatures of 17-19C at 850mb is more common for late April and early May. High temperatures in the upper 80s to around 90 degrees is normal for late April and early May and that is precisely what is in the forecast for this coming week. Latest NBM has forecast highs in the low to mid 80s for Monday and Tuesday across the lower deserts and then upper 80s to lower 90s Wednesday through the end of the week. Both high and low temperatures will be pushing daily records late this coming week. Daily record highs in Phoenix for the end of February are around 89-92F (see CLIMATE section below) and 92F is also the record highest February temperature. So there is even a decent chance of setting a new monthly record in Phoenix. The 07Z run of the NBM has a forecast high of 92F in Phoenix on the final day of February with around a 75% chance of 92F or higher. Lower desert high temperatures in the 80s to around 90F will lead to Minor HeatRisk and the heat will pose a health risk if you spend extended time outdoors in the afternoon without breaks from the sun and/or proper hydration. Besides the coming heat, the atmosphere in the Desert Southwest will remain dry through the next week and winds will generally be light with occasional late morning and afternoon breezes.

AVIATION

Updated at 0000Z.

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

No aviation weather concerns under increasing high level clouds during this TAF period. Easterly winds will briefly go NW'rly over the next couple hours and will return to an E'rly component during the overnight hours. Overall speeds will generally be aob 10 kts, but a few gusts into the teens are possible during the mid to late morning hours tomorrow morning.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns under some passing mid to high level clouds can be expected throughout the TAF period. Winds will generally be out of the west to northwest with periods of light variability this evening. Wind speed will generally be aob 7 kt.

FIRE WEATHER

Dry conditions will persist through the next week, with temperatures warming rapidly this weekend through the first half of next week. Besides a brief and small uptick in moisture during the middle of the coming week, MinRH values will be around 10-20% and overnight recoveries will be around 35-50% each day. Afternoon high temperatures will go from low to mid 80s Sunday through Tuesday to upper 80s to low 90s Wednesday through the end of the week, up around 15-18 degrees above normal. Winds will be light with an occasional afternoon breeze and follow typical diurnal directional patterns most days over the next week. There will be an uptick in easterly winds tomorrow morning across south- central AZ, with general winds up to 10-15 mph and gusts up to 20-25 mph across lower elevations (below 3000') and a bit higher over higher elevations, up to 15-25 mph sustained with gusts up to 30-35 mph. There may be another uptick in easterly winds at the end of next week, but forecast confidence is currently low. There is no precipitation in the forecast through next week.

CLIMATE

Daily High Temperature Records.

Phoenix --------- 2/25 92 (1921) 2/26 91 (1986) 2/27 92 (1986) 2/28 89 (1986) 3/1 89 (2016)

PSR WATCHES/WARNINGS/ADVISORIES

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