textproduct: NWS Phoenix

UPDATE

Updated Aviation Discussion.

KEY MESSAGES

- A weather system will pass to the north tonight into Monday dropping temperatures into the normal range, but dry conditions and mostly clear skies will continue to prevail.

- A second weather system is expected during the latter half of the week providing at least precipitation chances across the Arizona high terrain.

SHORT TERM /TODAY THROUGH TUESDAY/

The weather pattern is becoming more active across the Western U.S., but for the Desert Southwest little will change over the next few days. Large scale broad troughing has now settled in across the region with a shortwave trough well to the north across the Pacific Northwest and Idaho. Heights aloft are very slowly dropping, but it will have little effect on temperatures today as highs should be nearly identical to Saturday. The disturbance to our north will continue to track south southeastward into tonight, eventually passing across the Four Corners area Monday morning. Any precipitation chances with the system will stay well to our north, but we will see some passing higher level clouds tonight and some breezy northerly winds across the Lower CO River Valley on Monday. Temperatures will also drop a few more degrees on Monday with lower desert highs ranging between 68-72 degrees. Tuesday looks to be another transition day with the first system exiting to the east and another one quickly diving southward through the Pacific Northwest into the Great Basin. Weather conditions Tuesday will be again quite nice with sunny skies and highs mostly in the upper 60s.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

Models are beginning to come to a better consensus for the expected weather system later this week, but there is still enough spread to keep a good amount of doubt in our precipitation chances. The system will again take an overland trajectory, keeping moisture levels on the lower side, but it will at least be a good deal farther west than the one for tonight/Monday. The main shortwave is expected to pass across Nevada into eastern California Tuesday night/Wednesday morning before likely tracking right through our region Wednesday afternoon through the daytime hours Thursday.

Ensembles are now heavily favoring a fairly progressive trough with little chance of becoming cut off and retrograding to the west. This should result in at least some precipitation chances for northern and eastern Arizona from later on Wednesday through much of Thursday, but moisture will be a bit limited and the energy from the trough may be somewhat lacking. NBM PoPs have increased slightly from yesterday, but remain mostly between 15-30%. If the track holds true, it's likely these PoPs will improve over the next couple of days. The latest QPF amounts are still quite limited at basically nothing for southeast California and southwest Arizona to upwards of 0.1-0.25" over the higher terrain north and east of Phoenix. The system should not be all that cold, so snow levels will remain quite high limiting any potential snow to the highest peaks. Temperatures should however lower a bit more with highs falling more into the mid 60s across the lower deserts by Thursday.

AVIATION

Updated at 1705Z.

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

Little to no aviation weather concerns are expected through the TAF period. Winds today will remain light at or below 7 kts at all terminals and directions will follow typical diurnal tendencies. Toward the end of the TAF period, expecting some increasing northerly winds across the Lower CO River Valley by late Monday morning, Have introduced gusty winds at 16z Monday for KBLH. Clear to mostly clear skies will also prevail through the period with SCT high cirrus.

FIRE WEATHER

Dry conditions will continue to prevail early this week as a weak disturbance passes by to the north of the area. Temperatures will cool into the normal range starting Monday, while daily MinRHs continue to range between 25-35% with good to very good overnight recoveries of 60-80%. Winds will overall remain light through the period except for a period of northerly breezy conditions across the Lower CO River Valley on Monday. By Wednesday into Thursday, another weather system may bring precipitation chances to portions of the area with humidities increasing further.

PSR WATCHES/WARNINGS/ADVISORIES

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