textproduct: NWS Phoenix

KEY MESSAGES

- Dry weather and warming temperatures starting today, and lasting through Monday.

- Unsettled weather will return Tuesday and again late week, leading to a couple periods with rain chances over South Central Arizona and cooling temperatures near to below daily normals.

SHORT TERM /TODAY THROUGH MONDAY/

The shortwave that moved across northern AZ yesterday is now positioned along the boarder between NM and TX. Behind the shortwave, to our region's west, upper level ridging is building and will quickly move eastwards and strengthen over the Desert SW starting today.That being said, H5 heights will climb back up to between 577-580 dam by this afternoon, which will diminish any further rainfall and begin to trend temperatures back into the mid to upper 70s across the lower deserts. Further warming will occur heading into Monday where temperatures will increase to the upper 70s with the Phoenix Metro having near an 80% chance of hitting at least 80F.

LONG TERM /TUESDAY THROUGH FRIDAY/

By late monday night/early Tuesday morning another upper level trough will push inland with models now showing the core of this next system lifting to the NE through NV and UT. However the bottom of the trough will move through Arizona providing enough ascent to the region to increase PoPs back to between 60-90% across South-Central AZ, and 20-60% across SW AZ. PWATs Tuesday will also increase to over 200%, with the latest WPC QPF indicating Tuesday's rain totals between 0.25"-0.50" across the Greater Phoenix area, locally higher in thunderstorms, and close to 1.00" over Central AZ higher terrain to the north/northeast. However, considerable spread remains in the model guidance, with 25th-75th percentile QPF ranging between a few tenths to upwards of 1.25", focused over the higher terrain to the north/northeast of Phoenix. A 1-2 day break in the unsettled weather will then likely ensue following Tuesday, ahead of the next system.

During the latter half of the week, ensembles are pointing towards yet another upper level trough moving inland from the Pacific NW, however, there are still considerable discrepancies in the trajectory of this followup system (how far south it will propagate, which will impact the moisture return and placement of the best upper level ascent mechanisms). Due to this, confidence remains low for PoPs/QPF late in the work week, but at the very least, there is building consensus for an even cooler airmass to enter the region as a result of this second system. Latest NBM highs continue to trend towards the 60s to lower 70s by late week. However, the spread in the model guidance increases considerably on Friday, with IQRs on the NBM forecast temperatures increasing to 8F-10F.

AVIATION

Updated at 0525Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No aviation concerns are anticipated through the forecast period under mostly clear skies. Winds will maintain a light easterly component overnight and through much of the day Sunday. There is low confidence that a westerly shift will occur at KPHX Sunday afternoon. Speeds should remain aob 6 kts through the period.

Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns will exist through the forecast period. Winds will favor a W at KIPL overnight before switching out of the SE by Sunday afternoon. At KBLH, a N-NE wind direction will be common. Extended periods of calm and vrb conditions will be likely at both terminals, especially after sunrise Sunday morning. FEW to SCT low clouds with bases aoa 7 kt will persist over SE California.

FIRE WEATHER

Dry conditions and temperatures warming near to slightly above normal are expected starting today lasting through Monday before another weather system moves through the region on Tuesday. Despite the upcoming drier and warmer conditions afternoon minimum humidities will continue to range between 30-60% areawide through the week, following good to excellent overnight recovery. Widespread breezy and locally windy conditions in Southeast CA will develop with the next system on Tuesday. This system will also cool temperatures back into a below normal category. The next weather system will likely reach the area by Friday and result in even cooler temperatures and another round of rain chances.

HYDROLOGY

Gila: A Flood Warning remains in effect from Painted Rock Dam through the Dateland area through at least early next week due to water released from the dam. Water releases remain at 3000 cfs and are expected to remain at this level through the next several days. This will have the potential to flood farm fields and low- water crossings along the river downstream from the dam.

PSR WATCHES/WARNINGS/ADVISORIES

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