textproduct: NWS Phoenix

UPDATE

Updated 12Z Aviation Discussion.

KEY MESSAGES

- Unusually strong winds will impact the region today and Monday resulting in areas of blowing dust and critical to near critical fire weather conditions.

- Below normal temperatures will continue through the majority of this upcoming week.

- More tranquil weather conditions and a slow warming trend will arrive during the latter half of this upcoming week.

SHORT TERM /Today through Monday/

Upper level water vapor satellite imagery and objective analysis show that a Pacific trough has established itself over western CONUS. This trough will gradually push further south/southeast through tomorrow. As the trough pushes further into the Desert Southwest it will lead to decreasing heights aloft along with a tightening pressure gradient. This tight pressure gradient will pair with a strong jet leading to strong, gusty winds across the region. The trough is becoming more stabilized and thus the height falls and tightening pressure gradient isn't as dramatic as it was yesterday so winds are expected to gradually relax through tomorrow, especially across western portions of the CWA. Despite winds not forecasted to be as strong today a Wind Advisory remains in place through 11pm PDT tonight across the far SW corner of Imperial Country, where it is typically windier. Winds across the eastern portions of the CWA will be fairly similar to yesterday, maybe slightly weaker. Regardless, these windy conditions paired with low humidity (RH as low as 8-15% this afternoon), and very dry fuels will result in critical fire weather conditions for southern Gila County and the Tonto National Forest Foothills. The Red Flag Warning remains in effect for these locations through 8pm MST this evening. Winds are expected to decrease slightly again on Monday, which is why the Red Flag Warning has not been extended into Monday. However, conditions will still support elevated to near critical fire weather conditions for the eastern districts and rapid spread or growth will be possible for any new or existing fires. Elsewhere across the CWA elevated fire weather conditions will remain in place both today and Monday. Temperature wise, with lowering heights aloft confidence is excellent that temperatures will continue their cooling trend. Temperatures will be around 5-10 degrees below normal both today and Sunday with several lower desert locations forecasted to not reach 100 degrees. Morning lows are even forecasted to fall into the 60s and 70s by Monday morning.

LONG TERM /Tuesday through Saturday/

By Tuesday the Pacific trough will settle over Western CONUS allowing for negative height anomalies to remain in place over our region. The Pacific trough and corresponding negative height anomalies will remain in place through at least Wednesday. This will result in temperatures (both morning lows and afternoon high) several degrees below normal for this time of year. Afternoon high temperatures are forecasted to be in the upper 90s to around 102 degrees across the lower deserts and in the low to mid 90s across the higher terrain. Morning lows are forecasted to be in the mid 60s to mid 70s across the region. Ensemble model guidance remains in good agreement on the overall synoptic pattern through this upcoming week with high pressure slowly starting to push back into the Desert Southwest from the east and the aforementioned Pacific trough lifting north/northeastward. As a result, H5 heights aloft will start to increase leading to a gradual warming trend. The latest NBM has temperatures returning to near to slightly below normal by the end of the upcoming workweek. The high pressure system will continue to push into our region next weekend with H5 heights aloft continuing to rise. By next weekend afternoon high temperatures are forecasted to go back above normal and be in the 105-110 degree range.

Additionally with the Pacific trough settling over the region on Tuesday and Wednesday and then ridging slowly building back in during the latter half of the week, the breezy to windy conditions will taper off with only some minor afternoon breezy conditions expected across the Lower CO River Valley and the higher terrain east of Phoenix. Very dry conditions will also remain in place and thus there will be no rainfall chances through this upcoming week.

AVIATION

Updated at 1124Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: The main aviation concern will be gusty conditions this afternoon into the late evening hours. Gusts between 20-25 kts will develop by 18Z this morning, lasting through the evening. Directions will be mostly diurnally driven, however, a slightly earlier transition out of the west, as early as 15Z and periods of southerly cross winds during the transition period. With elevated winds region wide, lofted dust may have some minor slantwise visibility impacts, but no surface reduction are anticipated. Skies will be mostly clear through the TAF period.

Southeast California/Southwest Arizona including KIPL and KBLH: Strong winds will continue to be the main aviation concern through the TAF period. Winds at KIPL will remain westerly and gusting between 25-30 kts through most of the TAF period. More relaxed winds at KBLH this morning before gusts develop during the afternoon hours with speeds between 20-25 kts, with a more SW'rly component compared to KIPL. These enhanced gusts will have the potential to generate areas of dust that would impact slantwise and even surface VIS at times. Other than dust, skies will be clear through the TAF period.

FIRE WEATHER

Elevated to critical fire danger will continue through at least Monday due to low humidity, very warm temperatures, afternoon upslope/upvalley breezy conditions, and very receptive dry fuels. A Red Flag Warning remain in effect through this evening for the eastern districts. MinRHs will be in the 5-15% range through Tuesday and then drop to 5-10% beginning on Wednesday. Overnight recoveries will be poor to fair and in the 25-50% range through Wednesday night before dropping to a 15-30% range Thursday night. Wind gusts of 25-35 mph, locally higher possible, are expected again this afternoon and evening. These windy and very dry conditions will combine with the very dry fuels to create a risk of extreme fire behavior. Winds will gradually start to diminish during the beginning of the workweek. Temperatures will be below normal today and will stay below normal through the majority of the upcoming workweek.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...Red Flag Warning until 8 PM MST this evening for AZZ133.

CA...Wind Advisory until 11 PM PDT this evening for CAZ562.