textproduct: NWS Phoenix

KEY MESSAGES

- Unseasonably strong high pressure over the Desert Southwest will lead to well-above normal temperatures this week, with afternoon highs across the lower deserts pushing into the upper 80s to lower 90s by mid-week.

- Daily record highs and warm lows may be tied or broken in Phoenix, Yuma, and El Centro from Thursday through Monday.

- Dry, tranquil weather with zero rain chances are expected through this weekend.

SHORT TERM /TODAY THROUGH TUESDAY/

The upper-lvl pattern consists of a broad ridge of high pressure which now encompasses the entire western half of the CONUS. 500 mb hghts have risen to between 584-586 dam over our forecast area, or near the 98th percentile of climatology for late February. Despite a thin layer of high cirrus clouds currently progressing through the region, temperatures have quickly warmed into the upper 70s and lower 80s and are expected to top out in the mid 80s across the deserts of SE California, SW Arizona, and SC Arizona. The relatively strong sfc pressure gradient which brought breezy conditions to the foothills and higher terrain yesterday has finally relaxed and wind speeds will be much lighter through the rest of today and overnight. Dry and tranquil conditions will continue into tonight with temperatures settling into the low to mid 50s across the lower deserts and a few locations dipping into the mid to upper 40s.

The only sensible change in weather conditions on tuesday will be a noticeable increase in mid-to-high lvl clouds streaming into the region ahead of a strong AR event in N California and the PacNW. These clouds will do little to moderate temperatures however. Continued warming aloft and increase in mid-lvl hghts/thickness will cause highs to tick up by a couple more degrees on Tuesday. Highs Tuesday afternoon will close in on the 90 degree mark across the Imperial Valley of SE California and more solidly into the mid 80s across the SC Arizona lower deserts.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Little will change with the weather pattern during the latter half of the week and through the weekend, but temperatures are forecast to warm further and likely reach or top 90 degrees for a good portion of the lower deserts by the weekend. NBM forecast highs are shown rising to near 90 degrees in the Phoenix area by Thursday with most of the southeast California and southwest lower deserts flirting with the lower 90s. Guidance indicates H8 temperatures warming even further by the weekend, potentially reaching near record territory for this time of year for southwest portions of the Desert Southwest. Barring any thicker high clouds, which is not very likely, daytime highs should top 90 degrees across a majority of the lower deserts by Saturday. Daily record highs will be in jeopardy for at least Phoenix by Thursday as well as the all-time warmest day in the month of February, which is 92 degrees. The NBM shows a 50-60% probability of reaching 93 degrees or warmer in Phoenix on any day from Friday-Sunday.

Widespread Minor HeatRisk will develop by Wednesday, even affecting some higher terrain areas late week and through the weekend. Overnight lows in the 60-65 degree range will also become fairly common later this week. Although model uncertainty increases into next week, the ridge is favored to begin to break down and/or shift more to our southeast at some point early next week. This should start to bring temperatures down some, but only back into the 80s. There will be no chances for precipitation for our area through at least next weekend.

AVIATION

Updated at 1705Z.

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

No aviation concerns are expected during the TAF period. Winds will follow familiar diurnal trends with slightly later than usual turn to the W this afternoon/evening. FEW-SCT high cirrus will be present over the region through Tuesday morning.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation concerns are expected during the next 24 hours under FEW-SCT high cirrus clouds. Winds will be favored generally out of the W/NW at each terminals with speeds aob 7 kts.

FIRE WEATHER

Warm and dry conditions will prevail with temperatures pushing well above normal through the rest of this week. Afternoon highs will warm by a few degrees each day, reaching the lower 90s late week for much of the lower deserts. MinRH values will range from 10-20% and overnight recoveries improving to only 35-50% each day. Winds will overall be light and follow diurnal tendencies, with some occasional upslope breeziness in the afternoon and early evening.

CLIMATE

Daily High Temperature Records.

Phoenix Yuma El Centro --------- --------- --------- 2/25 92 (1921) 95 (1986) 94 (1986) 2/26 91 (1986) 96 (1986) 95 (1986) 2/27 92 (1986) 95 (1986) 96 (1986) 2/28 89 (1986) 97 (1986) 92 (1986) 3/1 89 (2016) 93 (1986) 91 (2016)

PSR WATCHES/WARNINGS/ADVISORIES

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