Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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475 FXUS65 KPSR 301130 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 430 AM MST Thu May 30 2024 .UPDATE...Updated 12z Aviation Discussion. && .SYNOPSIS... Dry and tranquil weather conditions will persist through at least the weekend, but expect continued above normal temperatures as high pressure generally dominates across the region. High temperatures each day across the lower deserts will remain several degrees above normal with readings between 100 and 106 degrees under sunny to mostly sunny skies. && .DISCUSSION... Little change in the weather pattern through the weekend is expected as our region continues to fall inbetween upper level troughing across the northern U.S. and the sub-tropical ridge positioned to the south. This will keep dry westerly flow in place and H5 heights near climatological normals. The dry air mass will also persist through at least the weekend with PWATs running around 70-90% of normal resulting in continued clear to mostly clear skies and low humidities. Temperatures will also remain stable over the next several days with readings on average 3-5 degrees above normal. Most lower desert locations will see daily highs reaching between 100-105 degrees into early next week. By next Monday and Tuesday, guidance continues to favor a weak cyclonic circulation forming just off the southern California and northern Baja coast. Eventually, this feature is likely to become fully or partially cut off from the main flow during the middle part of next week as it should strengthen a bit more and wobbles just to our west for several days. For now, guidance highly favors this disturbance staying over the Pacific or at most reaching into portions of southern California later next week, but either way it should have little impact on our sensible weather conditions. Moisture levels are likely to increase across the Southwestern U.S. next week, but the much of the moisture will stay to our west and north leaving near to slightly above normal PWATs for our area. As of now, the most we can hope for is some higher level cloudiness and maybe some low end rain chances across the Arizona high country at some point late next week into the following weekend. The main forecast concern is the potential for even hotter temperatures during the latter half of next week as the sub- tropical ridge currently to our south is expected to strengthen and shift northward through the Southern Plains and likely northwestward through much of the Desert Southwest into the Great Basin by around next Wednesday. Both the GEFS and EPS mean H5 heights are shown increasing to between 588-594dm over at least much of Arizona and New Mexico during the middle of next week. Model guidance is nearly certain of this ridge building over our region, but there are still differences on how strong it will be and how far west it can build due to the expected presence of the cut-off low. For now, guidance is definitely leaning toward hotter temperatures by next Wednesday through the rest of next week with the latest NBM forecast highs between 105-109 degrees over much of the lower deserts. If the cut-off low ends up closer to our region, temperatures are not expected to be that hot, but so far that is the less likely solution. Starting next Wednesday, the NBM shows up to a 20-30% probability of reaching 110 degrees for the warmest lower desert locations. Hot temperatures of this magnitude are not unusual for the first week of June as daily records for Phoenix range from 111-115 degrees and records for Yuma and El Centro are a degree or two higher. As temperatures reach near 110 degrees, this would put the majority of the area well within a Moderate HeatRisk. && .AVIATION...Updated at 1130Z. South-Central Arizona including KPHX, KIWA, KSDL, KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns will exist through the TAF period under mostly clear skies and at times FEW high clouds aoa 20 kft later in the period. Winds will favor light and diurnal tendencies across the Phoenix area terminals, with periods of variability preceding directions switches and occasional westerly gusts this afternoon into the teens. For the SE California terminals, SE winds will be favored through the afternoon at KIPL before turning W this evening, and S to SW winds will be favored through the period at KBLH. Overall, very similar wind patterns to the last 24 hours are expected across all sites. && .FIRE WEATHER... Hot and dry conditions will prevail into next week with daily highs remaining 3-5 degrees above normal. Overall light winds will follow diurnal tendencies each day with afternoon gusts in the mid-teens to around 20 mph. MinRH values will range between 5-10% each afternoon while overnight Max RHs range between 20-40% for most places. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Kuhlman AVIATION...Whittock FIRE WEATHER...Smith/Kuhlman