Area Forecast Discussion
Issued by NWS Flagstaff, AZ
Issued by NWS Flagstaff, AZ
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270 FXUS65 KFGZ 131051 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 351 AM MST Thu Jun 13 2024 .SYNOPSIS...Expect another round of abnormally warm temperatures today, even in the face of increasing cloud cover and some isolated, light rain showers. From this evening through Friday, a passing low pressure system will bring more scattered shower activity, and a slight chance for thunderstorms. Dry, warm, and breezy conditions return by the weekend, with a slight cooling trend early next week. && .DISCUSSION...Current satellite and upper-air analysis shows a 500 mb low centered off the west coast of northern Baja and a 500 mb ridge over northern Mexico. A southerly flow between these features has transported moisture into southern Arizona. For example, the dew point in Yuma, AZ is currently sitting around 50 degrees, which is about 5-10 degrees higher than this time yesterday morning. Moist air will continue to spread northward across the state today, bringing with it increasing cloud cover and chances (10-30%) for light rain showers. While this moisture will keep high temperatures a couple of degrees cooler than yesterday, abnormally warm conditions will persist and an Excessive Heat Warning remains in effect below 4000 feet within the Grand Canyon and lower deserts of Yavapai County through 8 pm MST. Otherwise, most locations will see a round of south-southwest winds, with gusts in the 20-30 mph range during the afternoon hours. From this evening through Friday, the aforementioned low will move across the state resulting in higher chances (20-50%) for showers, and a slight chance (10-15%) of thunderstorms and dry lightning. While rainfall amounts are expected to be meager, a few pockets of rainfall in the 0.2-0.4 inch range may occur, especially across northeast Arizona. As you would expect with the cloudy and unsettled weather forecast for Friday, daytime temperatures will dip a few degrees resulting in an end to the excessive heat. On Saturday, dry weather returns to Arizona as the low pressure system slides across the central United States. At the same time, the general model consensus predicts a long wave trough over the western United States will deepen keeping Arizona under the influence of a dry southwest flow aloft through at least mid- week. High temperatures may quickly rebound again on Saturday, with temperatures approaching excessive heat levels once again. This increase in temperature may be short-lived though, with a slow but steady cooling trend likely after that. Forecast uncertainty is high beyond Sunday. Model disagreements hinge on the strength of the developing longwave trough, as well as the timing of shortwaves traversing the general flow. Overall, the main hazard in the extended forecast is for critical fire weather. The majority of longer range models highlight Sunday and Monday as the period with the best combination of low relative humidity and strong surface winds. && .AVIATION...Thursday 13/12Z through Friday 14/12Z...Expect increasing mid-level cloud cover. Light and variable winds through 16Z-17Z, then south-southwest wind gusts 15-25 kts. Isolated -SHRA after 18Z, increasing after 00Z mainly along and east of KGCN-KFLG-KSOW line. Periods of MVFR visibilities possible under the heaviest showers. OUTLOOK...Friday 14/12Z through Sunday 16/12Z...Isolated to scattered -SHRA with isolated TS, mainly east of a KPGA-KINW- KSOW line through 00Z Saturday. Brief MVFR visibilities or lower possible under the heaviest showers. West-southwest winds gusting 10-20 kts Friday, becoming southwest with gusts 15-25 kts Saturday. && .FIRE WEATHER...Today and Friday...Hot temperatures will continue today before slightly cooling off on Friday. Chances for light rain showers Thursday afternoon across Yavapai and Coconino counties become more focused across eastern Arizona on Friday. Slight chances for thunderstorms are forecast from late tonight through Friday. The main hazards from these storms will be dry lightning and strong/erratic outflow winds. Southwest wind gusts 20-30 mph on Thursday will become more westerly 10-20 mph on Friday. Saturday through Monday...Above normal temperature return over the weekend, before cooling Monday. Mainly dry conditions with gusty, southwest winds and afternoon RH values 5-15% daily. Wind and humidity may approach critical fire weather thresholds on Sunday and/or Monday. && .FGZ WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM MST /9 PM MDT/ this evening for AZZ005-006-037. && $$ PUBLIC...RR AVIATION...RR FIRE WEATHER...RR For Northern Arizona weather information visit weather.gov/flagstaff