textproduct: NWS Phoenix

KEY MESSAGES

- Widespread breezy to locally windy conditions are expected this afternoon through this evening, and will continue tonight through early Monday morning across Southeast California following a cold front.

- Elevated to locally critical fire weather conditions are anticipated for a few hours this afternoon and evening for the Eastern Arizona higher terrain, where a Red Flag Warning will be in effect.

- Afternoon high temperatures will be near normal today and then drop to 4 to 6 degrees below normal for Monday and Tuesday before slowly warming back up again.

SHORT TERM /TODAY THROUGH MONDAY/

Broad troughing continues to encompass the Western CONUS with breezy to windy conditions again today and into early Monday morning. Another shortwave will be dropping south through NV this afternoon and evening before progressing eastward across UT and CO Monday morning. The pressure gradient will tighten in response leading to another wave of breezy to windy conditions lasting well into late this evening. Gusts across the entire CWA will generally be between 25-35 mph tonight with even stronger gusts (40+ mph) in southeast CA, and the higher terrain areas.

In Imperial County downsloping winds this afternoon/evening can even push gusts upwards of 50 mph. Additionally, a dry cold front is expected to drop south through southeast CA and southwest AZ tonight with rather strong N-NW post-frontal winds, especially across eastern Riverside County where gusts up to 40-50 mph are possible. Due to these factors a Wind Advisory remains in effect for the Imperial Valley area and then an additional Wind Advisory will begin for Riverside County and along the Colorado River Valley near midnight tonight, lasting into the morning hours. The area of most concern during this time will be along I-10, especially between Desert Center and the Indio Valley, where HREF probabilities of peak wind gusts >50 mph are maximized (60%), and can result in blowing dust and reduced visibilities.

These gusty winds this afternoon and evening will not only affect the western region but in the eastern higher terrain areas leading to elevated and marginally critical fire weather conditions. A Red Flag Warning remains in effect for southern Gila County and the Tonto National Forest where afternoon and evening winds are forecast to be strongest in combination with minimum RHs of 10-15% and dry fuels.

Otherwise, as the shortwave troughs pass just to the north of our region temperatures will also be affected, with high temperatures today in the low to mid 90s, or right around normal for this time of year. Temperatures drop further for Monday with lower deserts likely failing to reach 90F. There will also be a narrow band of PBL moisture and forcing along and just ahead of the cold front Monday morning. Enough to at least lead to some lower clouds in south- central AZ near sunrise, otherwise skies will be mostly clear. Additionally, there are a couple HREF members producing a few sprinkle showers out of these clouds, but overall PoP is under 10%.

LONG TERM /TUESDAY THROUGH SATURDAY/

As the potent weekend shortwave trough departs the Mountain West, to drive severe weather in the Plains, a measure of broad cyclonic flow over the Western U.S. will remain and likely persist through the remainder of the upcoming work week. Heights aloft will rebound though, closer to seasonal averages, and so temperatures are expected to warm through the middle of the week, with seasonally dry conditions continuing. Meanwhile, a strong midlevel ridge will remain nearly stationary off the Pacific Northwest Coast through much of next week, with most global guidance showing a subtropical jet forming under the ridge and developing a few weak disturbances. A few of which may be sent downstream and near/over the Southwest U.S.. Regardless of the details and how weak troughing over the West- Central CONUS eventually resolves, essentially all solutions currently show the region remaining completely dry, with periods of mid-high level clouds and slowly warming temperatures through the work week.

AVIATION

Updated at 1740Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:

The main aviation concerns will be a period of elevated cross- runway winds at KPHX late this morning followed by gusty W-SW winds this afternoon into the evening. Winds will remain generally out of the south around 10-11 kts with occasional gusts into the teens through late this morning. Winds will then shift out of the southwest by 20Z-21Z this afternoon with gusts up around 20 kts. Stronger gusts up to 25 kts are expected to materialize between 23Z-01Z and continue through 06Z-07Z. Winds will likely shift back to the SE at KIWA and KPHX late tonight before quickly returning to the SW early Monday morning. Skies will remain mostly clear through much of today and overnight with FEW high clouds moving in this afternoon and evening. FEW-SCT CU as low as 4-5 kft AGL may develop over the Phoenix Metro around sunrise Monday morning, but will only persist for a few hours.

Southeast California/Southwest Arizona including KIPL and KBLH:

Periods of gusty winds and reduced visibilities due to blowing dust will be the main aviation weather concerns throughout the TAF period. At KIPL, winds will maintain a westerly component while at KBLH winds will fluctuate from the south to southwest. Winds are expected to increase at KIPL early this afternoon with gusts up to 20-25 kts becoming common. A period of stronger winds (30-35kt) is likely in the evening (00-04Z). Brief visibility restrictions will be possible with the strongest gusts due to blowing/lofted dust. At KBLH, light southerly and at times VRB winds this morning will pick up through the afternoon, with gusts reaching up to 20 kt. A cold front will enter the area from the north and switch winds abruptly at KBLH overnight. Skies will remain mostly clear through most of this morning with FEW high clouds moving in this afternoon and evening.

FIRE WEATHER

Elevated and marginally critical fire weather conditions are expected through this afternoon and evening for a few hours as winds increase across the region. A Red Flag Warning remains in effect for southern Gila County and the Tonto National Forest for this afternoon through this evening. The winds will steadily increase through the afternoon, with peak wire weather conditions (strongest winds and lowest RH) likely between 1500-2000MST. Wind gusts in the warned area will peak around 25-35 mph and RH values will minimize around 10-15%. While RH increases above critical levels after 2000MST the elevated breezes are likely to continue through midnight, which may make controlling any new/existing fires challenging. Wind gusts up to 25-35 mph will be common across all districts this afternoon, but will be strongest across southeast CA with westerly sundowner winds in Imperial County up to 40-50 mph and northerly gusts up to 35-50 mph across much of eastern Riverside County later tonight through early Monday following a cold front passage around midnight. There will be very dry air following the front that will create elevated fire conditions across Riverside County, even during the overnight hours. Minimum RH values will be closer to 15-20% across the western districts. Lingering northerly breeziness down the Lower Colorado River is expected Monday, but this gradient wind should weaken heading into the afternoon and winds elsewhere Monday afternoon will be weaker than today with gusts up to 15-25 mph. Beyond Monday, weather conditions will be seasonally hot and dry (Min RHs around 5-15%), with winds mostly reaching up to 15-25 mph in the afternoons.

PSR WATCHES/WARNINGS/ADVISORIES

AZ...Red Flag Warning until 11 PM MST this evening for AZZ133.

CA...Wind Advisory from 11 PM this evening to 11 AM PDT Monday for CAZ560-561-564-568>570.

Wind Advisory until 1 AM PDT Monday for CAZ562.

Wind Advisory from 4 PM this afternoon to 11 PM PDT this evening for CAZ563-566-567.