Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/26/22

Area Forecast Discussion
National Weather Service Phoenix AZ
459 PM MST Fri Feb 25 2022 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... Dry conditons will persist as high pressure builds over the region through the middle of next next week resulting in a strong warming trend. Weekend temperatures will rebound back near the seasonal normals before warming to more than 10 degrees above average by the middle of next week. While likely remaining below daily records, readings during the middle of next week should be the warmest for the region since November. && .DISCUSSION... Early this afternoon, general cyclonic flow persisted across the SW Conus situated downstream of an East Pacific high amplitude ridge and just ahead of a weakening, positively tilted trough moving through the Great Basin. H5 heights have already rebounded to near 570dm, and the overall pattern was dislodging the current cold airmass in place (almost certainly the coldest weather impacting the forecast area for the next 9+ months). In fact, ACARS soundings have sampled 5C-10C of warming in the H8-H7 layer already this morning which will be translated through the lower troposphere this afternoon. The western hemispheric pattern through the middle of next week will be characterized by a stable high latitude omega block over Alaska/western Canada, while quasi-zonal flow and dampened extension of the ridge axis yields above normal heights/thermal profiles over the SW Conus. The aforementioned Great Basin will trough will slide through the CWA over the next 36 hours with little fanfare other than enhancing surface pressure rises across UT/CO, and resulting in somewhat elevated winds across the lower Colorado River Valley Saturday. Thereafter in the first part of next week, heights aloft will gradually increase albeit with quasi-zonal flow emanating from the Pacific. While this pattern will allow temperatures to moderate back into a normal (or slightly above normal) range, periods of thicker high clouds will be common which may conceivably hinder full mixing and daytime heating. Nevertheless, spread among NBM members is very narrow resulting in excellent forecast confidence into the middle of next week. More pronounced shortwave ridging will spread into the forecast area at least briefly during the middle part of next week yielding the warmest weather for the region in nearly 3 months. The greatest forecast uncertainties hinge on the magnitude of the midtropospheric ridge and residence time over the region. Recent EPS and CMC members are trending towards the warmest ensembles with H5 heights peaking around 582dm while the majority of GEFS membership paints a picture of a more dampened ridge. Overall ensemble mean forecasts suggest height/thermal fields only 1 normalized standard deviation above the late February climatology (around 90th percentile which still remains short of daily records); however historically, these spring warming events more often than not end up well above the mean and towards the upper end of the ensemble guidance envelop. Thus, there is good confidence high temperatures will end up 10F-15F above normal Wednesday and Thursday, with a very slim, but non-zero chance of nearing record territory (in general, records are low 90s in the beginning of March). At this time, NBM probabilities of hitting 90F range from around 15% around Phoenix to a 30-50% range for the warmer locations of SW AZ/SE CA. Eventually, ensemble output generally agrees on larger pattern realignment as the blocking pattern breaks down late in the week. This should result in one or more dry shortwave troughs passing through or near our region next weekend. Although NBM shows a much higher spread in possible temperatures during this period, some form of a cooling trend is probable depending on the depth of troughing entering the western Conus. && .AVIATION...Updated at 2355Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Winds will remain light and mostly favor normal diurnal sequences. Periods of light and variable conditions will also be seen. The current increase in high cloud cover will culminate with SCT-BKN decks this evening and then will clear out later tonight. Clear skies to persist through Sat. Southeast California/Southwest Arizona including KIPL and KBLH: Light winds at KIPL will favor a W to NW component through much of the period, while winds at KBLH favor a N to WNW component. Some breezy N winds with gusts into the low 20s will begin at KBLH by mid morning Sat. Otherwise, few to scattered mid and high clouds this afternoon through the early evening and then clear skies thereafter. && .FIRE WEATHER... Sunday through Thursday: High pressure will begin building across the region over the weekend and strengthen by the middle of next week. This will result in a warming trend with temperatures at least 10F above normal. Dry conditions will prevail through the period with minimum relative humidity values around 10 to 15 percent. Overnight recovery maximum values on the order of 30 to 50 percent across eastern districts and lower values of 20 to 35 percent western sections can be anticipated. Light winds will generally prevail through the period, with the exception of the Lower Colorado River Valley where daytime breeziness can be expected with gusts around 20 mph, especially on Monday. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook, Twitter, and at DISCUSSION...18/Kuhlman AVIATION...Sawtelle/Feldkircher FIRE WEATHER...Kuhlman