Area Forecast Discussion
Issued by NWS Flagstaff, AZ
Issued by NWS Flagstaff, AZ
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737 FXUS65 KFGZ 060502 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 1002 PM MST Wed Jun 5 2024 .SYNOPSIS...Much warmer temperatures and mainly dry conditions are expected through Friday as high pressure builds over the Southwest. There remains a slight chance for thunderstorms developing Thursday afternoon. Temperatures begin to cool gradually for this weekend with the potential for additional showers and thunderstorms. && .UPDATE...Look for milder temperatures overnight as a bit of moisture and its heat trapping qualities has crept across northern Arizona. Otherwise, dry conditions, light winds and mainly clear skies are in store. The remainder of the forecast is on track with the hottest daytime temperatures of the year in store for Thursday. A good day to take those heat precautions and protections seriously. && .PREV DISCUSSION /422 PM MST/...Tranquil weather conditions are taking place across northern Arizona as a high pressure ridge strengthens over much of the western half of the country. High temperatures this afternoon are forecast to be around 10 degrees above average, followed by roughly 15 degrees above average for Thursday and Friday. This is shaping up to be the warmest temperatures of the year so far and taking place quite early in the summer season. Excessive Heat Warnings remain in effect for Thursday and Friday for lower valleys and canyons below 4000 feet. Much, if not all, of northern Arizona will experience uncomfortable heat for the next two days. Be prepared. Global models show the ridge axis migrating eastward on Thursday, resulting in a switch to light south to southeast flow. This flow should allow for a slight increase in moisture advection in the mid-levels with PWAT values near average (~0.50"-0.60") for this time of year. Slight chances (15-20%) for isolated showers and high-based thunderstorms remain in the forecast for Thursday afternoon and evening, mainly confined to the Kaibab Plateau, San Francisco Peaks, Mogollon Rim, and the White Mountains. Due to the sufficient surface heating expected and lack of surface moisture, any showers and/or thunderstorms that do develop over the high terrain will likely be on the dry side with lightning and gusty outflow winds (30-40 mph) being the main threats. The classic "inverted-V" signature in various model soundings suggest this potential for Thursday afternoon. With this in mind, new fire starts will be possible. The good news is that outside of any erratic outflows from storms, winds should generally be light, 10-20 mph, from the south and west on Thursday. Afternoon winds thereafter are forecast to remain in the 10-20 mph range with occasional gusts of up to 25 mph from the southwest. According to both GEFS and EPS guidances, there are no strong wind events on the horizon, which is good just in case there is an undetected lighting fire start. Flow becomes more southwesterly on Friday with moisture advection confined to the White Mountains and along the AZ/NM border. A slight cooling trend develops on Saturday with daytime highs forecast 5-10 degrees above average, returning to near average (within 5 degrees) on Sunday as geopotential heights decrease in response to weakening high pressure and the potential for a low pressure trough to move inland from the Baja coast. Isolated showers and dry storms are forecast (15-30% chances) on Sunday as the weak trough moves overhead from the southwest. Additional chances are anticipated on Monday before drying out by mid-next week. With that said, confidence continues to increase in another warming and drying trend for the 8-14 day period. No indications of any significant moisture to the region on the horizon at this time. && .AVIATION...Thursday 06/06Z through Friday 07/06Z...Mainly VFR conditions expected. Slight chance for MVFR and gusty, erratic winds near ISO SHRA/TSRA near a KGCN-KFLG-KJTC line after 18Z. Light and variable winds, becoming W/SW around 10 kts after 18Z. OUTLOOK...Friday 07/06Z through Sunday 09/06Z...Mainly VFR conditions. ISO chance for MVFR and gusty, erratic winds in vicinity of KSOW/KJTC each afternoon. Winds W/SW 10-15 kts each day, becoming light and variable overnight. && .FIRE WEATHER...Thursday and Friday...Hot temperatures, with a slight chance for very light showers and thunderstorms in the high terrain. Dry lightning and gusty, erratic winds will be the main threat from any stronger storm. West/southwest winds around 10-20 mph with minimum afternoon RH 5-15% each day. Saturday through Monday...Cooler temperatures. Slight chance for light showers and thunderstorms over the Mogollon Rim and White Mountains, otherwise dry conditions. Winds southwest 10-20 mph with minimum afternoon RH 10-20% each day. && .FGZ WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning from 10 AM MST /11 AM MDT/ Thursday to 8 PM MST /9 PM MDT/ Friday for AZZ005-006-037. && $$ PUBLIC...McCollum/LaGuardia AVIATION...Humphreys FIRE WEATHER...Humphreys For Northern Arizona weather information visit weather.gov/flagstaff