Area Forecast Discussion

KEY MESSAGES

- Near normal temperatures through mid week will turn hotter going into the weekend with lower desert highs into the nineties as early as Friday.

- A trough approaching the West Coast will tighten the pressure gradient across the Desert Southwest. Expect widespread breezy to windy conditions Saturday and Sunday.

- The combination of single-digit afternoon RH and gusty winds will likely lead to elevated fire weather concerns this weekend.

SHORT TERM /TODAY THROUGH THURSDAY/

The system previously progged to bring light showers Thursday has trended much weaker and further south in the latest model runs. Analysis of the NAM and HRRR shows the cut-off low shearing apart as it moves over the Baja. Tranquil conditions persist. Highs will hover in the upper 80s to low 90s today. Expect high-level cirrus to persist.

For Thursday. While the mid-levels show a slight increase in moisture, the sub-cloud layer remains extremely dry with large T/Td spreads. Both the 06Z and 12Z HRRR runs show almost zero simulated reflectivity for the CWA. Consequently, PoPs have been lowered to <5% for the lower deserts. Any activity will be limited to virga or a few "dry" sprinkles with slightly higher probabilities (~5%) over the higher terrain of Gila County.

LONG TERM /FRIDAY THROUGH TUESDAY/

By Friday, the close low will be exiting to the region's east, but negative height anomalies will remain over much of the Desert SW. Even with negative height anomalies temperatures will begin to warm as upper level ridging begins to build over the West Coast. Temperatures in response to the building ridge will warm into the lower to mid 90s in the western lower deserts and in the lower 90s across south-central Arizona.

Over the weekend another low pressure system will develop off the Californian coast, which will help amplify the ridge over the Desert SW driving temperatures into the mid to upper 90s. Models point towards this next system moving into our region by early next week which will most likely return breezy to windy conditions, cooler temperatures, and possibly some higher terrain rain chances.

AVIATION

Updated at 1730Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No significant weather issues will exist through Thursday afternoon under FEW-SCT and at times BKN mid and high cloud decks (AOA 10 kft AGL). The overall wind pattern will exhibit typical diurnal tendencies with speeds aob 10 kts and occasional afternoon/early evening gusts in the teens. SHRA activity is expected to develop across southeastern AZ by Thursday afternoon, outside the Phoenix airspace, but VCSH conditions or virga/weak radar echoes cannot be entirely ruled out, especially for the southernmost terminal (KIWA). Confidence remains very low for VCSH or SHRA inclusion in any of the TAFs. The main concern from this, if any, would be the potential for a thinly scattered lower cloud deck late Thursday afternoon into Thursday night.

Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns will exist through the next 24 hours under generally FEW-SCT high clouds. Winds will favor a westerly component at KIPL and S-SW at KBLH with extended periods of variability possible. Winds may gust up to around 20 kts for a period at KIPL this evening.

FIRE WEATHER

Dry conditions along with warming temperatures will be observed through today. Winds will remain fairly light, following diurnal trends, with a few afternoon gusts to around 10-15 mph. MinRH values will be around 25-40% tonight before decreasing to 10-15% on Thursday. Thursday night MaxRH values will generally range between 25-60%. Gusty winds are expected to increase this weekend into early next week, which could lead to elevated fire weather conditions in some areas.

PSR WATCHES / WARNINGS / ADVISORIES

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