High pressure over the western United States allowed for high temperatures to top out nearly 10 degrees above normal at the end of the month. According to the Maricopa County Department of Public Health, two heat-associated fatalities occurred during this time.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PSR wrote it up.
High pressure over the western United States allowed for high temperatures to top out nearly 10 degrees above normal at the end of the month. According to the Maricopa County Department of Public Health, two heat-associated fatalities occurred during this time.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Phoenix, AZ wrote its last area forecast discussion before the first event at Sep 28, 4:37 PM MST, 23 minutes earlier.
Area Forecast Discussion National Weather Service Phoenix AZ 437 PM MST Mon Sep 28 2020 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... Dry conditions and clear skies will continue this week as strong high pressure remains entrenched across the Western United States. Temperatures will remain above normal through the period with highs generally topping out between 100-105 degrees on most days. A weak cold front passing through the region tonight into Tuesday morning will bring some breezy easterly winds across the region, especially for Tuesday morning through mid afternoon. && .DISCUSSION... The upper air analysis shows a high amplitude NE PAC ridge building across into W and Central Canada and the Western CONUS with a broad longwave trough across the Great Lake and Southern Plains. A dry cold front was also pushing southwest through the Great Basin in conjunction with a jet streak disturbance digging into NE NM and the TX Panhandle along the west flank of the longwave. There is dry N flow aloft at H5 north of a diagonal ridge axis with northeasterly CAA from the lower BL up through at least H7 through the Great Basin and even into SE CA. With the dry conditions and abundant insolation under the lingering southeast branch of large high pressure, along with BL thermal ridging in advance of the weak approaching cold front, highs today will reach into the low 100s for Phoenix and the far reaching lower deserts. The dry conditions with clear to mostly clear skies and above normal temperatures will continue through the coming week due to the dominating influence of the blocking ridge. However the brief influence from the dry, weak cold front beginning tonight has at least a fair chance to help drop regional S-Central AZ highs slightly on Tuesday to the upper 90s to 100 for Phoenix and S- Central AZ. Some breezy northerly winds are underway in parts of SE CA and the Lower Colorado River valley as the weak system moves in and helps to tighten the gradient. Also expect breezy easterly winds elsewhere from Monday night/morning through early to mid afternoon Tuesday with gusts near 25 mph. The gusty conditions combined with very dry conditions may also result in some slightly elevated fire danger in parts of SE CA and the Lower Colorado River starting today, and possibly for remaining areas for Tuesday morning through Tuesday afternoon. By Wednesday there is very little change forecast in the position of the large blocking ridge over the West and Southwest through Thursday or so. Then some possible weakening of the ridge may be seen on Friday and into the weekend when a near stationary weak low pressure disturbance possibly forms off the California coast. As a result above normal highs will rebound slightly for the mid to late part of the week before tapering back down slightly into the weekend and early next week. There is growing confidence in the models and ensembles that the warmest days will now fall on Thursday and Friday with highs ranging from 102 to 105 for Phoenix and surrounding deserts, and 104 to 107 degrees for out west. && .AVIATION...Updated at 2340Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Winds will continue to be variable with hints of a westerly direction across the terminal area at speeds mostly AOB 8 kts through 29/06Z, when the overnight easterly winds will become predominant. A dry cold front passing through the region will allow the easterly winds to strengthen with gusts commonly reaching 15-20 kts Tuesday morning between 16Z and 19Z. Easterly winds will then prevail through at least all of Tuesday morning with a few hours of a light variable/westerly wind possible for a few hours Tuesday evening between 30/00Z and 30/06Z. However, confidence in this late westerly wind shift tomorrow is not very high at this time. Southeast California/Southwest Arizona including KIPL and KBLH: There are no major aviation weather concerns. At KIPL, variable to northwesterly winds will prevail through the rest of today and tonight, becoming northeasterly early Tuesday morning around 29/16Z. Speeds will remain mostly AOB 7 kts. At KBLH, northerly winds at speeds of 8-12 kts, and occasional gusts up to 16 kts, will persist for the rest of today and through tomorrow morning when wind speeds will settle down and directions become more northeasterly. && .FIRE WEATHER... Thursday through Monday: Dry conditions and above normal temperatures will continue through the period as strong high pressure remains in place across the region. Highs will mostly range from 100-106 degrees under clear to mostly clear skies. Daily minimum RHs will remain low at less than than 10% through the weekend and only near 10% for Monday. Overnight RH recoveries will between 20-35%. Winds will remain mostly light through the period with a bit of afternoon breeziness for the coming weekend. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && DISCUSSION...Sawtelle AVIATION...AD FIRE WEATHER...Sawtelle/Kuhlman
The national radar mosaic for the moment the first event began.
2 heat. Local standard time, as filed.
One heat-associated fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances and location unavailable.
One heat-associated fatality was reported by the Maricopa County Department of Public Health, with their details, such as age, gender, circumstances and location unavailable.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Heat, Central Phoenix | 2020-09-28 | Unknown | Direct | ||
| Heat, Central Phoenix | 2020-09-29 | Unknown | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2020Every state in 2020This day in weather historyWarnings in Arizona, September 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 992789, 992790.