


Area Forecast Discussion
Issued by NWS Phoenix, AZ
Issued by NWS Phoenix, AZ
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107 FXUS65 KPSR 020520 AFDPSR Area Forecast Discussion National Weather Service Phoenix AZ 1020 PM MST Tue Apr 1 2025 .UPDATE... Updated Aviation && .SYNOPSIS... An unsettled weather pattern is bringing widespread gusty winds to the region today along with cooler temperatures. The strongest winds will remain focused across the southern Gila County higher terrain as well as portions of southeast California through the evening into tonight. Some chances for showers can be expected on Wednesday and on again Friday, with most of the activity favoring the higher terrain areas to the north and east of Phoenix. Temperatures will remain well below normal through the rest of the workweek before a warming trend takes shape starting this weekend. && .DISCUSSION... Early afternoon objective analysis shows a large trough over the Intermountain West with a strong mid level jet continuing to sag southward across our area. The increased gradient and higher momentum air aloft mixing down has led to widespread gusty winds this afternoon. Surface observations as of this afternoon showed peak wind gusts upwards of 25-35 mph for many areas across our CWA, while a few areas have seen gusts around 40 mph. The strongest winds will continue to remain focused across the southern Gila County high terrain as well as parts of southeast California, particularly portions of Imperial County. Wind Advisories are in effect for these areas through this evening into tonight. Given these winds, blowing dust will be a concern, especially across Imperial County where webcams are showing dust being lofted this afternoon. Blowing dust could lead to some visibility reductions. The longwave troughing pattern will settle across the Desert Southwest through the end of the week, bringing much cooler than normal temperatures as well as send a couple of shortwaves over the area bringing some precipitation chances. WV imagery currently shows one of these shortwaves near the northern California coast. This shortwave will continue to propagate toward the southeast and into Arizona going into Wednesday afternoon. While moisture will be quite meager with PWATs around 0.3-0.4", the vort max is expected to provide the necessary ascent needed to squeeze out some of this moisture. HREF data shows light showers developing across parts of south-central Arizona going into Wednesday afternoon, favoring areas to the north of Phoenix. Forecast soundings also indicate CAPE values up to 100-200 J/kg by early Wednesday afternoon and may lead to a few isolated thunderstorms. Rainfall amounts across our area will remain light generally around several hundredths with locally higher amounts with any thunderstorms that were to develop. Temperatures will bottom out well below normal Wednesday as highs struggle to get out of the 60s for many lower desert communities. Temperatures will gradually trend upwards for the latter part of this week as height fields gradually recover. Temperatures, however, will continue to remain well below normal Thursday and Friday as the region remains under troughing. Another weather system will take shape over the southwest CONUS going into Friday, bringing additional chances for light showers across the higher terrain for the end of the week. Global ensembles show the troughing pattern weakening and shifting east this weekend, leading to a more pronounced warming trend. Ensemble cluster analysis shows good agreement amongst ensemble members that upper level ridging will build into the region going into the start of next week. NBM shows temperatures returning to near normal readings Sunday before warming above normal early next week. By the mid to latter part of next week, ensemble clusters favor stronger ridging building across the West, boosting temperatures well above seasonal normals. && .AVIATION...Updated at 0520Z. South Central Arizona including KPHX, KIWA, KSDL, and KDVT: Unusual trends in wind directions, occasionally stronger gusts, and periods of lower cigs will all be weather concerns through Wednesday evening resulting in only low to moderate confidence of many forecast details. Confidence is good that a widespread shift to easterly winds will not occur tonight though some of the outer terminals such as KIWA and KSDL may become SE or variable for a few hours overnight and early morning. Models suggest 050-070 AGL cigs will develop mid morning through early afternoon with a tendency for bases to rise through the afternoon, though they may hover not far from the 060 threshold. Another round of gusty SW winds 20-25kt is likely mid/late afternoon. Isolated SHRA are possible around the airspace during the late afternoon with somewhat better confidence of greater coverage affecting some aerodromes - particularly KSDL and KDVT. There is growing model evidence that some of these SHRA north and west of Phoenix may create erratic winds and create a northerly component late afternoon/early evening with low confidence on resulting wind components Wednesday evening as cigs should begin to scatter. Southeast California/Southwest Arizona including KIPL and KBLH: Gusty winds will remain the greatest weather issue through Wednesday evening under periods of passing mid/high clouds. Westerly gusts 20- 30kt will be most pronounced in duration and magnitude at KIPL with only a possible brief early morning period of weakening. Gusts will be far weaker at KBLH, however wind directions may be much more variable through the period, albeit mostly favoring a westerly direction. There is model evidence of some lower cigs developing during the mid morning hours at KBLH, though confidence is only low to moderate. && .FIRE WEATHER... A weather system over the region will continue to promote widespread gusty winds into this evening. The gusty winds combined with Min RHs around 15-25% will continue to promote areas of elevated fire weather conditions. The strongest winds will remain focused across portions of southeast California, mainly across Imperial County, and the higher terrain areas of Maricopa and southern Gila Counties where gusts in excess of 40 mph are most likely to occur. Winds elsewhere will range between 20-35 mph. Weaker winds are expected on Wednesday but will likely gust between 15-30 mph, with the strongest winds expected across the higher terrain areas of south-central Arizona and across Imperial County. There will be some modest rain chances (20-50%) across the foothills and higher terrain areas to the north and east of Phoenix Wednesday afternoon, however, the CWR will remain low at 10-20%. A few isolated thunderstorms will also be possible, which could lead to locally erratic winds. Lighter winds are anticipated from Thursday onward. MinRHs will range between 20- 30% Wednesday-Thursday, between 15-25% Friday, and between 10-25% over the weekend. Overnight recoveries will be fair to good on most days, generally between 40-70%. Well-below normal temperatures are anticipated through the end of the week. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...Wind Advisory until 5 AM PDT Wednesday for CAZ562. Wind Advisory until 2 AM PDT Wednesday for CAZ563-566-567. && $$ DISCUSSION...Smith/Lojero AVIATION...18 FIRE WEATHER...Smith/Lojero