Area Forecast Discussion
Issued by NWS Phoenix, AZ

Current Version |  Previous Version |  Text Only |  Print | Product List |  Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
477 FXUS65 KPSR 092331 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 431 PM MST Thu May 9 2024 .UPDATE...
-- Changed Discussion --
Updated Aviation Discussion.
-- End Changed Discussion --
&& .SYNOPSIS... Just below normal temperatures today will warm to near normal tomorrow, with a gradual warming trend continuing into next week. The lower deserts will see increasing chances for triple digit afternoon high temperatures by the end of the weekend and heading into next week. Otherwise, typical springtime afternoon breeziness along with dry conditions will continue. && .DISCUSSION... Upper-level troughing continues across western CONUS and will help keep today`s afternoon high temperatures a few degrees shy of normal for this time of the year. This longwave trough will linger, but gradually weaken, over the region for the next few days. This will lead to temperatures going back above normal tomorrow with a gradual warming trend into next week. A weak jet at the base of the trough will enforce the typical springtime afternoon and early evening breeziness through at least the weekend. As the aforementioned trough weakens this weekend a strong ridge in the Pacific Northwest will be able to start to make it way into the Desert Southwest causing heights aloft to rise a little bit. This will allow for portions of the lower deserts to see triple digit afternoon high temperatures as soon as Sunday. The NBM gives portions of the lower deserts in southeast California and southwest Arizona a 60-80% chance of hitting 100 degrees on Sunday, which would put these communities in a Moderate HeatRisk. As for portions of the lower deserts in south-central Arizona, chances of hitting tripple digits increases by the beginning of next week. The NBM gives the Phoenix Metro a 30-50% chance of hitting 100 degrees on Monday. The ensemble guidance does have the trough linger over our region into early next week, so if it doesn`t weaken as much as currently forecasted then the triple digits may hold off until the middle to end of next week. .PREVIOUS DISCUSSION... Speaking of the middle to later portions of next week, ensemble clustering show considerable spread, as the evolution of the aforementioned trough will determine the magnitude of the warming trend during this period. However, there is a signal of more robust ridging building across the region late week, so temperatures topping the century mark would have a much higher likelihood should that scenario come to fruition. For now, the NBM deterministic forecast shows warming through Sunday, with highs hovering right near 100 degrees for the lower deserts through the early and middle portions of next week. Rain chances are essentially zero through the forecast period, but an increase in moisture starting Sunday and lingering into the middle of next week are expected to result in increasing clouds in the higher terrain during the daytime hours. && .AVIATION...
-- Changed Discussion --
Updated at 2330Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT; Southeast California/Southwest Arizona including KIPL and KBLH: Typical Spring diurnal wind tendencies are expected at all terminals through the next 24 hours, with speeds at or below 10 kts and afternoon gusts into the middle-teens. There will also be periods of light variability during the overnight/early-morning hours and during diurnal transitions. Skies will remain mostly clear.
-- End Changed Discussion --
&& .FIRE WEATHER... Slightly below normal temperatures today return to near normal tomorrow with a gradual warming trend into next week. MinRHs will be in the 5-10% across the lower deserts and in the 10-15% range across the higher terrain. Overnight recovery will be poor and in the 20- 40% range. Typical springtime breeziness continues through the weekend with afternoon and early evening wind gusts of 20-25 mph. These breezy conditions combined with dry fine fuels, and low RHs will likely create some elevated fire weather conditions. Dry conditions persist into next week. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Berislavich PREVIOUS DISCUSSION...Young AVIATION...Benedict FIRE WEATHER...Berislavich/Young