textproduct: NWS Phoenix

UPDATE

Updated 06Z Aviation Discussion.

KEY MESSAGES

- Unseasonably strong high pressure over the Desert Southwest will result in abnormally warm conditions for this time of year as afternoon highs approach 15 degrees above normal.

- Multiple daily record highs and overnight warm lows are likely to be tied or broken during the end of the week and into the weekend in Phoenix, Yuma, and El Centro.

SHORT TERM /TODAY THROUGH FRIDAY/

Current objective analysis reveals strong high pressure centered over the Baja Peninsula deflecting any and all significant weather well off to the north of the Desert Southwest. Meanwhile, dry and tranquil conditions prevail for our forecast area due to our proximity to the center of the anti-cyclone. H5 heights currently sit between 584-586dm (ranking above the 97th percentile against climatology), while H8 temperatures range close to all-time records for February over parts of the region. This setup will help continue the noticeable warming trend that began this past weekend, with lower desert temperatures this afternoon ranging from the middle 80s for South-Central AZ to the middle 90s for areas around the Lower Colorado River and Imperial Valleys. The forecasted high for El Centro, CA this afternoon is 94F, if this were to be reached, that would tie daily record for this date which was set back in 1986.

Trends indicate that the height and thermal profiles will only continue to be unseasonably high through the end of the week, allowing the meteoric rise of surface temperatures to persists as readings approach 15F-20F above normal for the end of February. To put this late winter heat into perspective, not only will the potential exist to see daily records tied or broken at multiple locations both Thursday and Friday, it is also not out of the question that all-time monthly temperature records are exceeded by the time the workweek is out.

LONG TERM /Saturday through Tuesday/

The persistent Conus longwave pattern featuring broad ridging in the west and predominant troughing over the east will be disrupted early next week as East Pacific energy progresses onshore forming weak negative height anomalies over the SW Conus. While the H5 high pressure ridge will become dampened over the weekend in response to incoming shortwaves, low level thermal profiles will be slower to respond with H8 temperatures still hovering around +20C and maintaining widespread lower desert afternoon readings above 90F (at or above daily records). Midlevel heights falls will become far more pronounced Monday and Tuesday with a preponderance of ensemble membership portraying either a weak positive tilt or partially cutoff cyclonic circulation. Moisture associated with this system should be extremely limited and capable of little more than squeezing out light showers over mountains of northern/eastern Arizona. Regardless, this pattern shift will allow temperatures to retreat from record territory, but likely still in an above normal category through at least the middle of the week.

AVIATION

Updated at 0520Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation weather concerns under periods of FEW-SCT high cirrus cloud decks can be expected throughout the TAF period. The overall wind pattern will exhibit diurnal tendencies with periods of light variability. The overall speeds will remain under 10 kts.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns under periods of FEW-SCT high cirrus cloud decks can be expected throughout the TAF period. Light west to northwest winds along with extended periods of light variability to even calm conditions can be expected.

FIRE WEATHER

Warm and dry weather will persist through early next week with temperatures reaching well above normal. Minimum afternoon humidity levels will generally fall into the teens across the lower elevations, and only somewhat higher in foothills and mountains. This will follow mostly fair to good overnight recovery of 30-60%. Wind speeds will largely remain under 15 mph with modest afternoon upslope gusts 15-25 mph becoming common. Overall conditions will be favorable for early spring prescribed burning operations.

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) 3/2 90 (2016) 94 (1910) 92 (2016)

PSR WATCHES/WARNINGS/ADVISORIES

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