Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/07/21

Area Forecast Discussion
National Weather Service Phoenix AZ
500 PM MST Thu May 6 2021 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... After one more day of high temperatures around 100 degrees across the lower deserts, a slight cooling trend is forecast into the weekend. Weak high pressure and dry conditions will prevail over the weekend into early next week keeping temperatures near to slightly above normal. Daytime breezy conditions will be common, especially over the next several days, while skies will mostly remain clear. Warmer temperatures for the latter half of next week are likely as high temperatures should creep back to around the century mark. && .DISCUSSION... High pressure is still firmly in control over the region, although the ridge axis has shifted east. Aircraft soundings are showing a slight warming of the lower troposphere from yesterday, but temperatures this afternoon are expected to peak near or one to two degrees warmer than yesterday. Phoenix managed to touch the century mark yesterday for the first time in 2021. So that is now out of the way and Phoenix has a greater than 50% chance of adding the second 100 degree day this afternoon, based on the latest NBM forecast. With the shift of the ridge axis, a moisture axis has developed from central Mexico up into the Desert Southwest. This axis however is just out of reach of the local CWA. So, while scattered convection is expected within this axis this afternoon and again Friday, all of the activity is expected to stay east of the area, mainly in New Mexico. The local CWA will continue to see mostly clear skies through Friday. A trough currently off the West Coast will begin moving inland tonight into Friday. The main vorticity maximum will move into the Pacific Northwest and a trough axis extending south down the entirety of the western CONUS. The incoming trough axis will at least lower heights aloft across the Desert Southwest starting Friday with 500mb heights mostly between 570-576dm lasting through the upcoming weekend as the trough deepens and stalls out across the northern portion of the Interior West. The lower heights will bring a slight cooling trend Friday through Monday as highs drop into the mid 90s over the weekend to as low as the lower 90s on Monday. Dry and fairly breezy conditions will be seen through Monday with the strongest gusts to around 30 mph across the western deserts on Friday, while afternoon gusts of 20-25 mph will be common elsewhere. There is still around a 30% probability temperatures trend slightly cooler (highs dipping to 90 or lower) and winds slightly higher (localized wind advisory). Most GEFS members are still clinging to a deeper slightly further south trough, which would lower heights further and tighten the pressure gradient. Regardless of the solution, all remain dry for for the local CWA through early next week. Model ensembles agree the trough to our north will stick around through next Monday or Tuesday, but temperatures are likely to start warming Tuesday into the middle of next week as the trough eventually pushes off to the east. Ensembles then point toward a modest ridge building across the Western U.S. during the latter half of next week, although the timing and strength of the ridge is still somewhat uncertain. NBM temperature guidance reflects the incoming ridge by boosting highs back to around 100 degrees later next week, or 5-8 degrees above normal. Seasonably dry conditions are forecast through next week with sky conditions likely remaining clear to mostly clear. && .AVIATION...Updated at 2355Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Breezy westerlies with gusts into the mid-upper teens will persist into the evening, with a chance for winds to remain elevated until almost the easterly switch time at about 07-09Z due to a gulf surge later this evening. An earlier than normal westerly switch may occur as early as 17-19Z with some afternoon gusts into the mid-upper teens developing by late afternoon. Expect FEW high cloud decks early in the period with skies becoming clear to mostly clear tonight. Southeast California/Southwest Arizona including KIPL and KBLH: For early this evening expect breezy SE winds at KIPL and breezy S-SW winds at KBLH with gusts near 15-20 kts. Beginning later tonight, light diurnal to light and variable winds will be favored at both sites. By late Friday afternoon some breezy S-SW winds will develop at KBLH with gusts into the upper teens possible. Skies will remain clear to mostly clear through the period. && .FIRE WEATHER... Sunday through Thursday: A weak low pressure system will remain nearly stationary across the Interior West through early next week providing near to slightly above normal temperatures and somewhat breezy day to day winds. Dry conditions will also prevail allowing daily min RHs of 5-10% while recoveries rise into the 20-30% range for most places, except near Imperial and Yuma where maximum values of 30-50% will be common. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Benedict/Kuhlman AVIATION...Sawtelle FIRE WEATHER...Benedict/Kuhlman