textproduct: NWS Phoenix

UPDATE...Updated 06z Aviation Discussion

KEY MESSAGES

- Unusually strong winds will impact the region today and Monday resulting in critical to near critical fire weather conditions and potentially some blowing or lofted dust.

- Below normal temperatures will continue through the majority of the upcoming work 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/

The forecast remains largely on track, with longwave troughing established and continuing to deepen over the Western CONUS. A couple centers of vorticity/upper lows can be distinguished upon analysis of midlevel water vapor imagery, one settling over the Great Basin and a second to its northeast over far northern Montana at this hour. Temperatures aloft and midlevel heights are anomalously low, around climatological minimums for this time of year over/near the Great Basin associated with the first vorticity center near the base of the longwave trough. Unsurprisingly, the flow aloft is also anomalously strong around the base of this trough, bringing NAEFS mean 700 mb wind speeds around 30-40 kts across much of northern/eastern AZ through today, near CFSR climatological maximum values. Despite jet energy and height packing over the region diminishing since their peaks yesterday, deep mixing heights typical for this time of year will help tap the higher momentum air aloft and realize gusts to between 30-40 mph over portions of the Tonto NF and Southern Gila County this afternoon into the early evening, and this, coupled with low RH and primed fuels will result in another day of very high fire danger. Thus, a Red Flag Warning remains in effect through 8 PM MST this evening for the aforementioned area. Widespread afternoon breeziness will continue today, with gusts to between 20-30 mph common today and stronger gusts in the typically wind prone areas of far Western Imperial County, where a Wind Advisory remains in effect through 11 PM PDT this evening. Winds will diminish further Monday, but widespread afternoon breeziness is still expected, and another wind headline may be needed for the southwest corner of Imperial County focused from late afternoon into the overnight hours.

While the base of Western CONUS longwave troughing settles over the region, midlevel heights will continue to decrease, supporting unusually "cool" temperatures for late June. In fact, ensemble mean H5 heights are forecast to bottom out sometime late Monday or otherwise during the first half of the work week in a 579-584 dam range across the forecast area, between the 3rd and 10th percentiles of climatology. Meanwhile, deep southwesterly flow will continue to promote drying throughout the column resulting in ensemble mean PWATs below 50% of normal for late June/early July across the entire state as we head into the middle of the week. Minimal (if any) cloud cover and very low humidities will promote excellent overnight radiative cooling, resulting in overnight lows much cooler than daily normals, in the 60s and lower 70s (except warmer in urban areas) across the lower deserts as early as Monday morning. These unseasonably cool overnight lows will be followed by afternoon highs in the upper 90s to lower 100s, between 4 and 10 degrees below the daily normals across the lower deserts.

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 0455Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT: No major aviation weather concerns under clear skies can be expected throughout the TAF period. The overall wind pattern will follow the typical diurnal tendencies with a period of southerly winds expected late morning before the westerly shift. Peak gusts near 20 kts will be common Monday afternoon/early evening.

Southeast California/Southwest Arizona including KIPL and KBLH: Elevated winds will continue to be the main weather issue throughout the TAF period. At KIPL, winds will generally be out of the west while at KBLH, winds will fluctuate out of the south to southwest. Gusts between 25-30 kts will continue at KIPL through the next couple of hours before subsiding through the overnight period. Another round of gusty winds near 20-25 kts at KBLH and upwards of 25 kts, occasionally higher, at KIPL can be expected once again late Monday afternoon/evening.

FIRE WEATHER

Elevated to critical fire danger will continue through at least Monday due to low humidity, very warm temperatures, breezy southwest winds during the afternoons/early evenings, and very receptive dry fuels. A Red Flag Warning remain in effect through this (Sunday) evening for the eastern districts. Afternoon minimum humidities between 8-15% through Tuesday will drop to a 5-10% range beginning Wednesday. Poor to fair overnight recoveries between 25-45% through Wednesday night will decrease into a 15-30% range Thursday night. Wind gusts of 25-35 mph and locally stronger are expected to linger into this 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 remain below normal through the majority of the upcoming workweek, with lower desert highs around 100F through midweek.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...None. CA...Wind Advisory until 11 PM PDT this evening for CAZ562-566.