textproduct: NWS Phoenix

UPDATE

Updated Aviation Discussion.

KEY MESSAGES

- A cold front will exit the area later this morning with lingering morning precipitation across eastern Arizona. Winds will remain breezy for much of today.

- Another weather system clipping the area Wednesday will bring more windy conditions and precipitation chances mainly over the Arizona high terrain.

- Yet another system Thursday night into Friday will keep temperatures cooler than normal through the end of the week with additional chances for light showers across the high terrain.

SHORT TERM /TODAY THROUGH WEDNESDAY/

The weather across the region has finally gotten more exciting with a decaying weather system now affecting much of the region. This unsettled weather pattern will last through the end of the work week with two other drier but colder weather systems skirting across northern portions of the region.

A distinct cold front is currently moving across central Arizona bringing a narrow band of rain and enhanced wind gusts along and just ahead of the front. Rainfall amounts with this band have generally been around 0.10" to upwards of 0.25". Localized wind gusts to around 40 mph have also been reported with the strongest gusts shifting into eastern Arizona closer to sunrise. A Wind Advisory remains in effect for portions of the higher terrain east of Phoenix through late morning. Temperatures today will be noticeably cooler with readings likely staying below 70 degrees for much of the south-central Arizona lower deserts to the lower 70s in Yuma and El Centro. Winds will remain breezy for much of the area today, especially across southeast California where the gradient will begin to tighten again this afternoon out ahead of the next approaching weather system.

The next weather system is colder and is currently centered just off the coast of northwest Washington. However, it is already in an occluded state and will be weakening quickly as it dives southward today into tonight. The biggest concern for our area will be the enhanced winds aloft with H8 winds increasing out of the west at 45-55 kts across southern California tonight to 30-40 kts across southern and central Arizona Wednesday morning. A Wind Advisory has been issued for all of southeast California and southwest Arizona with the strongest winds likely occurring early morning Wednesday across southeast California where higher terrain areas may see gusts up to around 50 mph. Gusty winds generally between 30-40 mph will spread throughout the rest of southern and central Arizona by mid morning and last at least into the early afternoon hours before gradually diminishing.

Most of the energy from the system will bypass our area to the north on Wednesday, but there should be enough jet support with the passing shortwave to create some shower activity across northern Maricopa County into Gila County mainly during the afternoon hours. PoPs have increased slightly with chances now 40-50% for the Phoenix area to 60-80% north of Phoenix. The lack of good moisture will however keep precipitation amounts fairly low with amounts at most 0.10-0.25" over some higher terrain areas northeast of Phoenix. Snow levels will drop Tuesday night into Wednesday morning down to around 5500 feet before rising closer to 6000 feet in the afternoon as the main shower activity moves through the area. Some light snow may occur over the highest peaks with at least some potential for a dusting of light snow along Highway 60 north of Globe Wednesday evening.

Temperatures will also be quite chilly Wednesday with morning temperatures starting out in the mid to upper 40s as winds become gusty. Make sure to dress warmly if going outside Wednesday morning.

LONG TERM /THURSDAY THROUGH SUNDAY/

Broad troughing will persist across the Western U.S. on Thursday and through Friday across our region as a third weather system is expected to track from along the Pacific Northwest coast Thursday morning reaching northern Arizona Friday morning. High temperatures Thursday may be the coolest of the week with readings from the lower 60s in the Phoenix area to the mid to the upper 60s across the western lower deserts. Overnight lows are also forecast to dip into the upper 30s to the mid 40s, but it could even be colder if it were not for the high likelihood of lingering elevated winds and clouds.

Model guidance is finally starting to come to a consensus for precipitation chances Friday with chances likely being very similar to the Wednesday system. The best moisture and forcing should be across the northern half of Arizona, but we should at least get some scattered shower activity reaching into the south- central Arizona lower deserts Friday morning. Precipitation amounts again should be on the light side, but some uncertainty remains as far as how much and how far south the shower activity will reach. Friday's high temperatures will be very similar to Thursday, but as drier air and light winds filter into the area Friday night more efficient cooling should lead to our coldest morning on Saturday. Lows Saturday morning very well could dip into the upper 30s for some of the Phoenix metro with rural lower desert areas into the mid 30s.

Upper level ridging should then move over the region this weekend with temperatures quickly climbing to above normal starting Sunday. Guidance favors the ridge to persist into early next week with NBM forecast highs back into the lower 80s for next Monday and Tuesday.

AVIATION

Updated at 1200Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: A cold front has passed over the terminals bringing temporary MVFR or lower VIS and/or CIGs as well as gusty south to southwest winds. MVFR CIGs are now mostly east of the terminals early this morning as SHRA activity moves out of the airspace. Lower cloud decks with bases between 4-7 kft AGL will linger through the morning followed by gradual improvements this afternoon. Anticipate winds to favor W/SW through early this evening, with occasional gusts into the teens and otherwise speeds AOB 11 kts. Confidence on winds late this evening into the overnight hours is lower than usual, however, most guidance shows winds shifting out of the SE ahead of a second weather system and attendant cold front that will move through Wednesday. This second system will present another period of gusty south to southwest winds by mid morning Wednesday, as well as another period of VFR CIGs and chances for SHRA mostly north of the Phoenix area.

Southeast California/Southwest Arizona including KIPL and KBLH: Extended periods of gusty southwest winds will be the primary aviation weather concern through the next 24 hours under FEW-SCT mid and high cloud decks. Winds AOB 12 kts this morning will then restrengthen by 17-19Z, with gusts to 25-30 kts becoming common this afternoon. Confidence is low on the amount of decoupling overnight, with some guidance showing winds becoming light and even shifting SE at KIPL, however, most guidance indicates gusty winds continuing. If confidence increases in winds decoupling overnight into early Wednesday morning, future TAF updated may need to include a mention of LLWS.

FIRE WEATHER

A weather system and associated cold front will impact the region early today with rain chances across the eastern districts mostly ending by this afternoon. Breezy conditions will continue today and pick up again on Wednesday as gusts once again reach above 35 mph in some areas. Another couple rounds of light shower activity will be possible across the Arizona high terrain on Wednesday and again Friday morning as two quick moving disturbances move across northern Arizona. Afternoon MinRH values will range between 25-40% across the lower deserts to 35-60% over higher terrain areas through Friday. Overnight recovery will range from good to excellent. Drying and warming conditions are expected for the coming weekend with MinRHs dropping into the teens for the lower deserts and temperatures rising to above normal.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...Wind Advisory from 8 AM to 4 PM MST Wednesday for AZZ530>533-535- 536.

Wind Advisory until 11 AM MST this morning for AZZ557-558-563.

CA...Wind Advisory from 7 AM to 3 PM PST Wednesday for CAZ565-567.

Wind Advisory from midnight tonight to 3 PM PST Wednesday for CAZ560-561-563-564-566-568>570.

Wind Advisory until 3 PM PST Wednesday for CAZ562.