textproduct: NWS Phoenix

UPDATE

Updated 00Z Aviation Discussion.

KEY MESSAGES

- Well above normal temperatures and dry weather will prevail across the entire region through the coming week.

- Record setting highs and warm lows will be possible across the lower deserts today and Monday, including Phoenix.

SHORT TERM /TODAY THROUGH MONDAY/

Upper level water vapor satellite imagery and objective analysis reveal strong upper level ridging still in place over the Desert Southwest along with a weak shortwave trough moving onshore in southern CA. The weak shortwave will move through our area later in the day on Monday (see long term discussion below). The ridge has H5 heights of 582-584 dm, which is above the 90th percentile of climatology. This unusually strong ridge for this time of year is resulting in temperatures 10-15 degrees above normal and high temperatures around their daily records. In fact, as of 1:13pm MST Phoenix Sky Harbor set a new record high temperature of 79 degrees, which breaks the old record of 78 set in 2010. With a couple hours of heating left, that new record could climb even higher. Elsewhere across the lower deserts afternoon highs will range from the upper 70s to low 80s and in the upper 60s to mid 70s across the higher terrain. SImilar temperatures are forecasted for tomorrow. Tomorrow's record high temperature for Phoenix is 79 degrees and the NBM is forecasting a high of 80 degrees, so another record could be broken tomorrow. Periods of high clouds, associated with the aforementioned shortwave, will be common across the region today and tomorrow.

LONG TERM /TUESDAY THROUGH SATURDAY/

The passing weak shortwave trough on Monday will briefly knock down H5 heights to between 578-580dm, but it will barely impact temperatures as highs should only drop 2-3 degrees Tuesday before warming again later this week. Another strong ridge is seen pushing eastward in behind the exiting trough with H5 heights briefly rising back to between 582-584dm on Wednesday. The center of the ridge is expected to stay well to our west, but heights over our region are still forecast to remain at or above the 90th percentile of climatology through at least midweek. Daytime highs for the latter half of the week are likely to top out anywhere from 76-80 degrees, or at least 10 degrees above normal. Eventually, ensembles show a deeper trough passing across the Northwestern U.S., potentially dipping into a portion of the Great Basin into the Central Rockies by next weekend. This should flatten the ridge some, but it is still too early to tell how much it will affect our region and if temperatures will drop much next weekend. Either way, the pattern will continue to support dry conditions across the Desert Southwest through the entirety of the upcoming week. Longer range guidance is still suggesting a pattern shift by Christmas with a trough setting up off and along the West Coast. If this continues to hold, we may see precipitation chances around or just after Christmas.

AVIATION

Updated at 2329Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns will exist through the TAF period. Winds will be light (aob 10 kts) and should remain predominantly easterly at the Phoenix Metro terminals through this evening. At the SE California TAF sites, winds will be mostly light and VRB through much of the afternoon before switching out of the N-NW at KBLH and W at KIPL this evening. Periods of SCT high clouds will continue to progress through the region this afternoon and evening before looking to clear out by late tomorrow morning.

FIRE WEATHER

Strong high pressure will result in warm and dry conditions continuing through the upcoming week. Highs in the upper 70s to the lower 80s will be common across the lower deserts, or upwards of 10 to 15 degrees above daily normals. Winds will follow familiar diurnal trends with occasional breeziness across the higher terrain areas. MinRHs this week will range from 15-25% while overnight recoveries will generally be between 40-70%.

CLIMATE

Daily Record Highs

Phoenix ------- 12/15 79 (1969)

PSR WATCHES/WARNINGS/ADVISORIES

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