textproduct: NWS Phoenix

UPDATE

Updated Aviation

KEY MESSAGES

- Slightly above normal temperatures will persist through Friday with gradual drying across the region.

- Temperatures will warm again this weekend with readings returning to around 10 degrees above normal. - A few showers and thunderstorms will be possible early next week across the eastern Arizona high terrain.

SHORT TERM /Today through Friday/

The weather across the region is now being driven by dry west northwesterly flow around a large Pacific trough currently moving east southeastward through the Pacific Northwest. Cooler air has also settled into the region behind the cold front that moved through the region yesterday, resulting in our coolest forecast overnight lows since mid March. The rest of today will continue to bring pleasant weather conditions with highs mostly in the mid 80s across the lower deserts under mostly sunny skies.

The track of the Pacific trough will bring the center through Wyoming on Friday, but a trailing trough axis is expected to clip the Four Corners area. Despite the trough axis mostly missing our region, a tightening pressure gradient across the northern half of Arizona will help to bring increased northerly winds through the area, particularly down the Lower Colorado River Valley. Models are now showing the potential for Advisory level winds mainly along ridgetop locations across eastern Riverside County through the Chocolate Mountains focused during the latter part of the morning hours into early afternoon Friday. Even drier air will also surge southward into our area later Friday through Friday night dropping surface dew points to between 10-20 degrees by Saturday morning.

LONG TERM /Saturday through Wednesday/

A mostly quiet weather pattern is expected for the weekend and through the first half of next week as a eastern Pacific ridge initially moves into the Western U.S. this weekend. This will help to quickly boost temperatures with highs topping 90 degrees across the lower deserts on Saturday and into the low to mid 90s on Sunday.

Models have also been trending toward a weak shortwave trough tracking across northwest Mexico and southern Arizona on Sunday, while the flow in the lower levels turns out of the southeast. Model consensus as of now shows a brief 12-24 hour period on Sunday of moist southeasterly flow into Arizona, potentially raising low level mixing ratios to between 6-7 g/kg across the eastern Arizona high terrain. If this moisture does make its way into eastern Arizona by the afternoon hours, some convection is likely to develop. The latest NBM shows this potential with PoPs now as high as 30-40% across eastern Gila County. The drier conditions into the lower deserts will most certainly prohibit any convection getting close to the Phoenix area.

By Monday, moisture should begin to decrease again likely ending any rain chances across the area. Upper level ridging will still be in charge over much of the Western U.S. going into the middle of next week and this should keep our region under overall dry conditions with temperatures staying stable in the low to mid 90s.

AVIATION

Updated at 1705Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major weather issues will exist through Friday afternoon under period of high cirrus decks. Confidence is moderate that wind directions will switch to westerly earlier than usual this afternoon, then persist longer into the overnight. Occasional gusts around 20kt will be possible late afternoon/early evening.

Southeast California/Southwest Arizona including KIPL and KBLH: The main weather hazard through Friday afternoon will be periods of very gusty winds as occasional high cirrus decks spread over the region. Wind speeds will be more pronounced at KBLH with 20-30kt gusts becoming common Friday morning as directions veer from SW to north. Gusts at KIPL should only peak around 20-25kt with directions westerly through the overnight, then becoming northerly Friday mid morning.

FIRE WEATHER

Dry weather returns to the region with temperatures hovering slightly above normal through Friday. Minimum humidity levels will fall into a 15-25% range today with even drier values closer to 10% Friday. Fair to good overnight recovery of 40-70% will deteriorate into a poor to fair 20-50% range. Enhanced wind gusts 30-40 mph will be possible in western districts on Friday creating elevated fire weather conditions, while other areas will only see modest afternoon breeziness. Lighter winds and temperatures rising to well above normal are then anticipated for the weekend. Moisture is expected to briefly increase across eastern Arizona this weekend potentially bringing chances for showers and thunderstorms across the higher terrain on Sunday.

PSR WATCHES/WARNINGS/ADVISORIES

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