textproduct: NWS Phoenix

Update

18Z Aviation Discussion

KEY MESSAGES

- Chances for light rain will end from west to east by late morning with skies becoming sunny by the afternoon.

- Slightly above normal temperatures are expected today through Friday with gradual drying taking place across the region.

- Temperatures will warm again over the weekend into next week with highs reaching the low to mid nineties by Sunday.

SHORT TERM /TODAY THROUGH THURSDAY/

An upper level shortwave and a modest cold front are currently tracking across the region early this morning providing ample lift for some light rain showers and virga. There is plenty of moisture in the upper levels, but moisture within the low and mid levels is sparse except for along and just ahead of the cold front. Hi-res CAMs show more scattered virga and light rain over the next few hours before forming a more definitive line of showers by around 6 AM as it passes through the Phoenix area. Even though the radar is picking up a lot of returns, we have yet to record any measurable rainfall across the lower deserts. Some higher terrain areas in southern California and western Arizona have managed to pick up some rainfall, but mostly under 0.10". As the front moves through the rest of Arizona later this morning, lower desert locations are likely to get see some sprinkles, but most will not receive any measurable rainfall. Higher terrain locations north and east of the Phoenix area are likely to see some measurable rainfall with localized amounts 0.1-0.2" possible.

Breezy to locally windy conditions will occur the rest of the morning mainly associated with the frontal passage and again during the afternoon hours focused across southeast California and the Arizona high terrain. Cooler air will also filter into the region from the west keeping daytime highs in the low to mid 80s across the lower deserts. Once the disturbance exits well to the east tonight into Thursday, drier northwesterly flow will settle over the region keeping skies clear to mostly clear. Temperatures Thursday are forecast to warm slightly, but still only topping out in the upper 80s.

LONG TERM /FRIDAY THROUGH TUESDAY/

A quiet weather pattern is expected going into the weekend and through at least the first part of next week. A Pacific trough will track well to our north on Friday keeping temperatures just a few degrees above normal. A modest ridge will then move into the region over the weekend quickly boosting temperatures as highs top out around 90 degrees Saturday and into the low to mid 90s on Sunday. This ridge will somewhat stick around into early next week, but it will likely be undercut by a very weak shortwave on Monday before another Pacific trough potentially moves into the Western U.S. on Wednesday. Dry conditions are likely to prevail the entire time with the only chances (5-10%) for any showers across the far eastern Arizona high terrain. NBM forecast temperatures look quite stable for the first half of next week with highs hovering around 95 degrees, or roughly 10 degrees above normal.

AVIATION

Updated at 1705Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns expected throughout the TAF period. Westerly winds can be expected through this evening with occasional afternoon/early evening gusts reaching 20-25 kts. Speeds will subside under 10 kts later this evening. Winds will then shift out of the east during the overnight period. FEW-SCT cloud decks aoa 8 kft will prevail into this afternoon before skies become clear by this evening.

Southeast California/Southwest Arizona including KIPL and KBLH: The main aviation weather concern will be some gusty westerly winds through this evening. At KIPL, westerly winds will persist throughout the period with gusts this afternoon peaking at 20-25 kts, with the potential of even higher gusts near 30 kts for a period early this evening. Speeds will gradually subside during the overnight period. At KBLH, winds will generally fluctuate between the south to southwest with some afternoon gusts near 20 kts, before subsiding by this evening. Mostly clear skies will persist through this evening before some high cirrus cloud decks move in during the overnight period.

FIRE WEATHER

A weak cold front pushing through the area this morning will bring scattered light showers with little measurable rainfall. Breezy westerly winds will also affect the area today with gusts as high as 25-35 mph with the frontal passage and again this afternoon across southeast California and the Arizona high terrain. MinRHs today will mostly be between 20-30% before drier air gradually moves in lowering MinRHs to 15-25% Thursday and 10-15% starting Friday. Afternoon breezy conditions will be possible on both Thursday and Friday focused more across the western districts. Lighter winds, temperatures rising to well above normal, and low humidities are then anticipated for the weekend.

PSR WATCHES/WARNINGS/ADVISORIES

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