textproduct: NWS Phoenix

KEY MESSAGES

- Dry and generally quiet conditions will continue through next week with temperature warming from near normal to above normal levels.

- Sub-freezing temperatures expected for higher terrain areas including southern Gila County tomorrow morning.

SHORT TERM /TODAY THROUGH SATURDAY/

Our region remains under the influence of a longwave trough, which can be seen on water vapor satellite imagery. This longwave trough will continue to promote cooler temperatures across the region. There is a wide range of temperatures out there early this morning, with lower desert locations any where from the mid 40s to low 50s, with higher terrain areas in the mid to upper 30s. These temperatures are similar to a few degrees cooler than they were at this time yesterday. Temperatures will continue to cool through the morning and are forecasted to bottom out at temperatures similar to yesterday morning (urban lower deserts: mid to upper 40s, rural lower deserts: upper 30s to low 40s, and higher terrain: upper 20s to mid 30s). With temperatures similar to yesterday a Freeze Warning remains in place across portions of southern Gila County. Afternoon high temperatures today will also be similar to yesterday, with highs in the mid 60s to upper 60s across the lower deserts and in the upper 50s to low 60s across the higher terrain.

On Saturday, a high pressure system over the eastern Pacific will move southeastward, but remain well off the coast of southern California. With this high pressure system moving eastward, that will in turn push the longwave trough eastward. So, H5 heights will rise from 573-576 dm today to 576-579 dm tomorrow. This will result in temperatures being a few degrees warmer. Afternoon high temperatures will be right around normal across south-central Arizona (upper 60s lower deserts and low to mid 60s higher terrain) and be a few degrees above normal across southwestern Arizona and southeastern California (upper 60s to low 70s). Morning lows will also be a few degrees warmer tomorrow, but remain in the 40s to upper 30s across the lower deserts and in the low to mid 30s across the higher terrain. With high pressure moving in, dry and tranquil weather conditions will persist.

LONG TERM /SUNDAY THROUGH THE END OF NEXT WEEK/

By Sunday the aforementioned high pressure system in the eastern Pacific will have moved further south and east and will stall just off the California coast. With the high pressure pushing further east the longwave troughing, that had been keeping our region cooler, will also move eastward and will finally exit our region. Despite the center of the high pressure system remaining off shore through the middle of next week, much of Western CONUS will be under the influence of its eastern flank. H5 heights will rise to around 580-583 dm on Sunday and then rise to 582-585 dm by the middle of next week. This will result in a gradual warming trend. However, through early next week multiple shortwaves will be moving from the Pacific NW/southern British Columbia down into the Plains that will temporally dampen the ridge, but, the ridge will quickly rebound. If any of these shortwaves are able to push into the Desert Southwest at all, it would briefly stall our warming trend for a day. Nevertheless, afternoon high temperatures, region wide, will go back above normal on Sunday and warm to around 8-10 degrees above normal by the middle of next week. Afternoon high temperatures are forecasted to go from the low 70s (mid to upper 60s) across the lower deserts (higher terrain) on Sunday to the mid to upper 70s (upper 60s to low 70s) by the middle of the week.

By the end of next week and heading into next weekend, the ridge will finally push onshore with the center of the ridge eventually moving over the Desert Southwest. The ridge will be weakening as it move onshore, however, with it moving directly overhead temperatures will continue to gradually warm through at least the end of next week. H5 heights will rise into the 583-586 dm range by the end of next week. This will result in afternoon high temperatures 10-12 degrees above normal and morning low temperatures 6-8 degrees above normal. For the end of next week, afternoon high temperatures are forecasted to be in the upper 70s to near 80 degrees across the lower deserts and in the low to mid 70s across the higher terrain. Morning lows are forecasted to be in the 50s across the lower deserts and in the 40s across the higher terrain. Additionally with the a ridge dominating the region, dry and tranquil conditions will continue through next week and into next weekend.

AVIATION

Updated at 0450Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns expected throughout the TAF period. The overall wind pattern will continue to exhibit light diurnal tendencies along with extended periods of light variability to calm conditions. A band of high clouds will move through later tonight through early Friday morning before clear skies prevail the rest of the day.

FIRE WEATHER

Dry conditions will continue to prevail across the region through next week. Temperatures will be near to slightly below normal, warming above normal during the weekend, and then going 10-12 degrees above normal by the end of next week. Winds will be light and tend to follow their typical diurnal tendencies. Humidities over the next week will stay elevated with MinRHs mostly ranging between 20-35% much of the time, with good to very good overnight recoveries.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...Freeze Warning until 9 AM MST this morning for AZZ556-560-562.

CA...None.