Area Forecast Discussion
Issued by NWS Flagstaff, AZ
Issued by NWS Flagstaff, AZ
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366 FXUS65 KFGZ 120503 AFDFGZ Area Forecast Discussion National Weather Service Flagstaff AZ 1003 PM MST Tue Jun 11 2024 .SYNOPSIS...Expect hot temperatures for the next couple of days, with brief cooling on Friday from the onset of a low pressure system. Slight chances for showers/thunderstorms return on Thursday and Friday, followed by dry, warm, and breezy conditions for the weekend and into next week. && .UPDATE...Clouds have cleared this evening across northern Arizona as drier air moves in from the southwest. Expect cool, near average temperatures tonight with little to no wind. Daytime temperatures will continue their increasing trend for Wednesday and Thursday with most locations likely to experience the warmest temperatures of the week on Wednesday. The Excessive Heat Warning remains in effect for Wednesday and Thursday for our lower valley/canyon locations. An upper-level low, currently off of the southern California/northern Baja coast, will eventually move inland on Thursday, resulting in isolated to scattered showers and thunderstorms across northern Arizona. As this low makes landfall and treks across Arizona Thursday into Friday, it will most likely become a weaker, open wave/trough with limited moisture availability. The potential for dry lightning and gusty outflows are the main threats. Southwest winds do look to increase for this weekend, with gusts of 25-35 mph likely, continuing into Monday. This would increase the potential for critical fire weather conditions, especially after a few days of high-based storms. The forecast remains on track with no changes needed at this time. && .PREV DISCUSSION /356 PM MST/...An area of high pressure will continue to bring hot temperatures this week, with daytime highs averaging 5-10 degrees above normal. As a result of the increasing temperatures, the Excessive Heat Warning for many areas below 4000` remains valid for Wednesday 10 AM MST through Thursday 8 PM MST. It`s highly encouraged to avoid strenuous activity during the hottest part of the day (~10AM-8PM) and stay hydrated. Relief from the heat is likely in store for much of northern Arizona late Thursday through Friday as a low pressure system moves inland from off the southern California Coast. There is not an abundant amount of moisture associated with this disturbance, but there looks to be enough forcing to get a few isolated to scattered showers going. The U of A WRF model shows precipitation chances increase west to east across our CWA as early as Thursday morning and lasting through Friday. Which brings up the potential for temperatures to not get as warm on Thursday, but that will all depend on exact timing/moisture availability/and location of precipitation. If temperatures do not have the opportunity to reach the highs we are projecting, the Excessive Heat Warning could be expired early. Outside of precipitation associated with the incoming low, increased winds are also expected. Although winds are below any product threshold/criteria, there will be continued elevated fire weather concerns. Ideally, relative humidities will increase enough with the slight up-tick in moisture, but fuels are fairly dry across northern Arizona and any storm with enough instability could produce lightning - potentially leading to a natural fire start. Warm temperatures will quickly return over the weekend, but a cooler/zonal looks to return over much of the Southwest by Monday. This will keep daytime highs near normal for this time of year, and winds on the breezy side. && .AVIATION...Wednesday 12/06Z through Thursday 13/06Z...VFR conditions persist through the period. Light and variable winds overnight, becoming W/SW 10-15 kts gusting 20-30kts after 16Z and until ~02Z Thursday. OUTLOOK...Thursday 13/06Z through Saturday 15/06Z...VFR conditions, outside of brief periods of MVFR in -SHRA/-TSRA after 00Z Friday, but could be earlier Thursday depending on how models continue to trend with moisture. Gusty, erratic winds possible near thunderstorms. Winds west/southwest 10-20 kts with gusts 20-30 kts each afternoon. && .FIRE WEATHER...Wednesday and Thursday...Expect dry and hot weather, with afternoon RH values from 5-15%. West/southwest wind gusts 15-25 mph on Wednesday, increasing to 20-30 mph on Thursday. Chances (10- 30%) for isolated, showers and thunderstorms begin late Thursday. Friday through Sunday...On Friday, a passing low pressure system will bring slightly cooler and more cloudy weather, but afternoon humidity will remain in the 8-16% range at most places. Chances (20- 50%) for showers, and a slight chance of thunderstorms, are forecast primarily along and north of the Mogollon Rim. Winds will shift to the west/northwest, expect in the vicinity of storms where erratic outflow winds are possible. Dry and warmer weather, along with breezy southwest winds return Saturday and Sunday. && .FGZ WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning from 10 AM MST /11 AM MDT/ Wednesday to 8 PM MST /9 PM MDT/ Thursday for AZZ005-006-037. && $$ PUBLIC...LaGuardia/Konieczny AVIATION...RKR FIRE WEATHER...RR For Northern Arizona weather information visit weather.gov/flagstaff