textproduct: NWS Phoenix

KEY MESSAGES

- Fluctuating temperatures along with breezy to locally windy conditions will accompany a few weather systems as they traverse the region.

- The stronger and slower moving area of low pressure will present rain chances to the region for the end of the weekend and into the start of next week

- High pressure, along with consistent above-normal temperatures, make their return by the middle portion of next week

SHORT TERM /TODAY THROUGH FRIDAY/

Current 500mb RAP analysis reveals a decent upper-level trough moving through the Great Basin and Intermountain West. An associated a cold front has reached down into the Desert Southwest and has helped provide some breezy to locally windy conditions to portions of Southeast California this morning. Although the peak of the winds has likely been observed, it will not be the last of the gusts that we see. Winds 25-30 mph will be widespread across lower desert areas, while higher gusts 30-35 mph will be more common for higher terrain areas, especially those out in SE CA such as the Chocolate Mtns and the western portions of Joshua Tree NP. Due to the cooler air aloft and the previously- mentioned cold front, temperatures across our forecast area will continue their cooling trend with highs for the lower deserts generally in the middle 70s to around 80 degrees.

By the end of the workweek, a secondary shortwave will split from the previous trough, eventually sagging southward toward the Baja Peninsula. As this evolution occurs, breezy to locally windy conditions will stick around, mainly for the Lower Colorado River Valley up through the western peaks of Joshua Tree NP, which the latter could potentially see gusts reach advisory levels. As of now, no wind products have been issued for portions of the park due to the isolated nature of the strongest winds. If gusts were to reach 40 mph or higher, they would most likely be focused over the tallest ride tops. One thing that appears more certain is that temperatures are likely to see their lowest values over the next week on Friday due to a reinforcing feed of cooler air to the region. MaxTs for that afternoon will be in the lower to middle 70s, right around and even slightly below normal for this point in March.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Models continue to show good agreement in the incoming troughing feature developing into a cut off low starting Saturday. The core of this developing cut- off low will likely set up just off the coast of Northern Baja Peninsula as early as Saturday afternoon, and looks to remain fairly stationary over the weekend. This system is not expected to bring any notable moisture into the region until Sunday afternoon but some uncertainty still remains with the extent of moisture increase and location. However, even with this uncertainty models are still suggesting PWATs increasing to anywhere between 150-180% of normal by Sunday night. This has led to models projecting the best chances for precipitation Sunday night into Monday afternoon. Eastern Arizona in the higher terrain areas have the best PoP chances, near 40-50% with QPF values most likely no more than 0.25". Outside of the higher terrain, QPF totals are expected to be mostly between 0.05-0.10", while many areas may not see any precipitation at all as the activity will be very light and scattered across the lower deserts.

Afternoon high temperatures will continue to fluctuate through early next week then steadily climb starting Tuesday through the rest of the week. As the cut-off low begins to set up over Baja on Saturday, the region will be under the influence of lingering negative height anomalies, keeping high temperatures in the mid to upper 70s. As the cut-off low tightens over the NW Baja coast, the region will begin to warm as the lower heights will be too far to the region's SW. This will lead to afternoon highs Sunday warming back into the low to mid 80s. These temperatures will lead to the lower desert areas being under Minor HeatRisk throughout the weekend. As the core of the cut-off low progresses eastwards over Northern Mexico starting Monday, temperatures yet again will cool slightly in response. High temperatures Monday are expected to be in the mid to high 70s. By Tuesday the cut-off low will be to the region's east, ejecting into Western Texas and into the Plains. Over the Desert SW H5 heights will then be able to steadily climb, leading to a steady increase in temperatures with highs back in the mid to high 80s by around Wednesday.

AVIATION

Updated at 1745Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Gusty west winds through at least early this evening, potential slantwise visibility reductions from lofted dust, and low confidence on wind directions Friday morning will be the main aviation weather concerns during the TAF period under clear skies. Winds have already begun to shift out of the west across the terminals. Confidence is high that gusts to around 20-25 kts will develop by 20-21Z. Gusts will peak late in the afternoon, with occasional readings around 25-30 kts. Between 03-05Z this evening, speeds will subside noticeably, though some gusts into the teens may linger into the overnight hours. Friday morning, confidence is low on a full E/SE wind shift, and so have opted for VRB winds at KPHX. Regardless, speeds should be under 10 kts during that time.

Southeast California/Southwest Arizona including KIPL and KBLH: Gusty north northwesterly winds and the potential for brief VIS reductions (primarily at KBLH) due to localized blowing dust will be the main aviation weather concerns through Friday morning under clear skies. Afternoon wind gusts up to 25-35 kts are expected at KBLH, whereas gusts will not be as strong at KIPL, mostly around 20-25 kts. Gusts will subside later this evening and tend to back out of the NW, staying generally between 7-12 kts overnight through Friday mid morning. Once again, if there is sufficient decoupling at the surface at KBLH, some minor LLWS conditions may develop, particularly between 11-15Z Friday. However, confidence is very low in LLWS meeting criteria for inclusion in the TAF.

FIRE WEATHER

The weather pattern will become increasingly active through the rest of the week as a series of dry disturbances cross the Southwest. The current passing system continues to bring light diurnal winds which will begin to strengthen bringing breezy to windy conditions today. Dry conditions will persist across the region with minimum relative humidity values staying entrenched between 10-15% through Saturday, while overnight recoveries will only reach the 30-50% range. Winds are expected to strengthen significantly after sunrise Thursday, with west gusts of 25-35 mph in the Phoenix area and peak WNW gusts of 30-45 mph across southeast California, leading to elevated fire weather concerns before a potential slight increase in moisture arrives Sunday into Monday.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...None. CA...Wind Advisory until 6 PM PST this evening for CAZ560-561-564- 568>570.