Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/25/21

Area Forecast Discussion
National Weather Service Phoenix AZ
520 PM MST Wed Mar 24 2021 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... Lingering light showers will affect Gila County through this afternoon, while breezy to locally windy conditions will persist along the Colorado River and southeastern California. The weather pattern will likely remain unsettled into the weekend as another slow moving weather system moves into the region starting Thursday. This system will bring widespread windy conditions for Thursday afternoon, along with additional chances for light showers mainly across central and eastern Arizona. Below normal temperatures will last through at least Friday before a warming trend likely pushes readings above normal starting Sunday. && .DISCUSSION... Visible satellite shows clouds encircling the center of an upper level low over northeastern Arizona. Light showers have occasionally drifted off the Mogollon Rim into the higher terrain east of central Phoenix all day. While most showers have been light, some instability has allowed a few convective showers capable of producing small hail to develop. Lightning has been nearly nonexistent, so far, with only one or two cloud flashes detected. For the rest of this afternoon, light to moderate showers are anticipated to continue east of Phoenix but lingering moisture farther west could allow a few to develop over the lower desert. Otherwise, skies will continue to clear across the rest of the forecast area through the rest of today and tonight. Another embedded shortwave within broad western troughing is anticipated to strengthen and dig into the Southwest tomorrow following a similar trajectory as yesterday`s wave. Ensemble guidance indicates a strong 850 mb jet of 35-45 kt winds will form and stretch across the forecast area late Thursday morning and afternoon. Meanwhile, the latest available ECMWF EFI retains indications for strong wind potential across a wide portion of south-central Arizona and southeast California tomorrow. Wind speeds of 15-30 mph will be common while gusts exceeding 40 mph are anticipated. As such, Wind Advisories have been issued for much of the forecast area. With these winds, blowing dust will also be a concern. While rain has fallen in some areas since Tuesday, rainfall amounts and coverage may not have been enough to tamper the blowing dust potential. The areas most prone to blowing dust are Pinal County south of Phoenix and portions of southeast California but other areas could see isolated/scattered impacts from blowing dust. While not every location might see reduced visibility from dust, Blowing Dust Advisories have been issued to highlight the increased threat. Localized areas of reduced visibility below 1/4 mile are also possible, such as where dust channels form, depending on local landuse. If blowing dust does occur, lofted blowing dust could linger over many areas through tomorrow evening. An inland trajectory of this system will keep moisture levels fairly low, but there should be sufficient moisture for at least scattered light showers starting Thursday evening after the passage of the cold front across the central and eastern Arizona high terrain. Precip chances mainly over the high terrain are likely to continue into Friday, and possibly Saturday, if this turns into another closed low. Given the low moisture levels, latest forecast QPF amounts are rather low with storm totals less than 0.25" across much the high terrain and likely little if anything over the south-central Arizona deserts. Snow levels are likely to drop to 5500-6000 feet at times during the event, but accumulating snows should mostly be relegated to the Mogollon Rim and the White Mountains. Temperatures will remain near to below normal the next few days as tomorrow`s system reinforces a cooler airmass. Highs fluctuate between the upper 60s/low 70s to the mid 70s through Friday before ridging aloft supports a warming trend this weekend. If Thursday`s system is slow to eject eastward and lingers, the warm up could be delayed by a day or so. Nevertheless, afternoon highs have a 70% chance of reach 80 degrees across SE CA and SW AZ by Saturday, and 98% chance of reaching 85 degrees by Monday. Farther east in the Phoenix area, there is a 50% chance for highs reaching 80 degrees by Saturday and 73% chance for reaching 85 degrees by Monday. && .AVIATION...Updated at 0010Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Moderate westerly component winds will taper off and become light and variable to light and a southerly component by early to mid evening. Winds will transition to an easterly component shortly after midnight tonight. FEW-SCT decks aoa 8 kft are expected to dissipate early this evening. Elevated southeasterly winds mid morning Thu to transition first to southerly during the late morning, then to westerly in the early afternoon. Westerly winds on Thu likely to become rather strong and gusty by mid-late afternoon as a rather robust Pacific weather system moves into the region.Gusts upwards of 20-30 kt are possible. These strong winds likely to produce areas of blowing dust as well, but confidence is still too low at this point to include BLDU at KPHX. A more likely concern will be slant-range visibility reductions for aircraft on approach into the terminals. BKN-OVC mid-level CIGS likely to return as well during the day on Thu near 16-18 kft along with isolated sprinkles and virga. Southeast California/Southwest Arizona including KIPL and KBLH: Winds will favor a northwest-west-southwesterly component during the early evening, with winds at KBLH to become southerly late tonight along with some LLWS developing Thu morning as shown in the TAF. Westerly winds at KIPL and southerly winds at KBLH likely to become rather strong and gusty by mid-late morning on Thu as a rather robust Pacific weather system moves into the region. Gusts upwards of 25-35 kt are possible. These strong winds likely to produce areas of blowing dust as well with visibilities falling to 4-6 sm in BLDU at the sites. In addition, slant-range visibility reductions for aircraft on approach into the terminals are expected. BKN mid-high level CIGS likely to return as well during the day on Thu. && .FIRE WEATHER... Saturday through Wednesday: Winds are anticipated to follow more typical patterns with speeds mostly at or below 10-15 mph in the afternoon. The area will undergo a warming and drying trend with temps reaching the mid 70s to mid 80s across the board. This will cause afternoon min RH values to frequently drop into the 8-15% range. Overnight recoveries will also decline a few percentages each day and eventually settle into the 20-40% range early next week. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Blowing Dust Advisory from 11 AM to 8 PM MST Thursday for AZZ530>540-542>544-546-548-550-551-553>555-559. Wind Advisory from 11 AM to 8 PM MST Thursday for AZZ530>563. CA...Blowing Dust Advisory from 11 AM to 8 PM PDT Thursday for CAZ563>570. Wind Advisory from 11 AM to 8 PM PDT Thursday for CAZ560-561- 563>570. Wind Advisory from 5 AM Thursday to 5 AM PDT Friday for CAZ562. && $$ DISCUSSION...AD/Khulman AVIATION...Sawtelle/Percha FIRE WEATHER...AD