Arizona, 2018Excessive Heat in Arizona, September 22 to 27, 2018
September 22 to 27, 2018 · NWS PSR · 2 events in 2 counties and zones
Strong high pressure aloft along with plentiful sunshine allowed for temperatures to reach dangerous levels during the latter half of September. Temperatures at Phoenix Sky Harbor airport reached as high as 105 degrees during this time, which was enough to result in several heat-associated fatalities.
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.
- Tornadoes
- Tropical storms and surge
- Floods
- Wind
- Hail
- Winter weather
- Heat and drought
- Cold
- Fire, smoke and dust
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- Deaths
- 4
- Injuries
- 0
- Property damage
- None recorded
- Crop damage
- None recorded
- Events
- 2
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.
Strong high pressure aloft along with plentiful sunshine allowed for temperatures to reach dangerous levels during the latter half of September. Temperatures at Phoenix Sky Harbor airport reached as high as 105 degrees during this time, which was enough to result in several heat-associated fatalities. According to Maricopa County Department of Public Health, 4 heat-associated fatalities occurred during this time. Without adequate precautions, highs in the triple digits, or even the 90s, are sufficient to cause serious health problems. As reported by the Maricopa County Department of Public Health, data are aggregated and unfortunately, specifics such as age, gender, location of fatalities, precise dates, and circumstances cannot be obtained.
What forecasters said that day
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 21, 3:02 PM MST, 8 hours 58 minutes earlier.
Area forecast discussion, Sep 21, 3:02 PM MST, 8 hours 58 minutes before
Area Forecast Discussion
National Weather Service Phoenix AZ
302 PM MST Fri Sep 21 2018
.SYNOPSIS...
As drier air continues to move into the region expect a slight
warming trend beginning today and into the weekend. Daytime highs
will reach the low 100s beginning today and remain very near these
above normal levels through the coming week with little day to day
change expected. Precipitation and storm chances are very low and
generally not expected through the forecast period with the
occasional exception of the higher elevations to the east.
&&
.DISCUSSION...
Current midday visible satellite is showing areas of mostly fair
weather cu across southwest and south-central AZ with radar
painting a couple of modest isolated storms in some western desert
areas. It's been a rather humid day so far with elevated surface
dewpoint temperatures currently ranging from the 50s to 60s.
Likewise, boundary layer moisture and dewpoints remain elevated
from just the lower deserts to SE CA with a low level dryline to
the northeast of the Phoenix metro. Similarly, the afternoon SB
CAPE field coincides with the elevated boundary layer moisture
field--over the lower deserts and SE CA and ranges from 1000 j/kg
near Phoenix to 2000-3000j/kg from SW Maricopa cty to SE CA. SPC
mesoscale analysis also shows a flattish strong high pressure
system over south-central AZ and NW Mexico with H5 heights near
589dam. There is also a weak H5 to H3 shortwave crossing southern
CA with models showing that this feature will soon be absorbed
into the westerly flow north of the ridge.
The models and ensembles are in fair agreement on maintaining the
flat ridge in control through the weekend and early next week
centered just to our south with broad troughing and the dry westerly
flow just to our north. This pattern will continue to support hot,
above normal temperatures and mainly dry conditions. Dry westerly
flow at H5 and above continues to support a general drying trend
into next week, with H7 and above joining in by Sunday afternoon.
However, models show that boundary layer and H8-H7 moisture may not
be as quick to dry out as much or quite as fast due to occasional
relatively modest moisture advection out of NW Mexico through
early next week.
As far as the sensible weather goes however, expect very little day
to day change with above normal temperatures in the low 100s
amidst low storm and precipitation chances through the period.
Although the low 100 degree weather will be about 3-6 degrees above
normal and is therefore be considered relatively hot, from an
absolute sense these temperatures represent a significant improvement
over last week's heat wave. On Tuesday a relatively dry, shallow and
weak trough axis will move across the region and try to draw some NW
Mexican moisture north into parts of AZ, although models show the
isolated storm activity associated with this feature will likely
be confined to far SE-E AZ as well as north-central AZ.
&&
.AVIATION...
South-Central Arizona including KPHX, KIWA, and KSDL and :
Southeast California/Southwest Arizona including KIPL and KBLH:
Strong high pressure aloft, a dry airmass, and weak sfc pressure
gradients to keep skies mainly CLR across the entire region through
Saturday. Winds to remain mainly on the light side (10 kts or less),
mostly following typical diurnal trends, except that winds will
likely remain easterly at the Phoenix area terminals all day on
Saturday.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Monday through Friday:
Temperatures will continue to remain 3-5 degrees above seasonal
normals from Sunday through the end of next week. Mainly dry
conditions are expected, except for a slight chance for a few
isolated showers/storms over the higher terrain north and east of
Phoenix on Tuesday, as a bit of moisture is briefly pulled northward
into the region. Minimum humidity levels will remain around 10-15
percent for the lower deserts and 15-25 percent for the higher
terrain north and east of Phoenix, but with fair to excellent
moisture recovery overnight and afternoon wind gusts below 15-20 mph
should help mitigate any fire weather concerns.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
DISCUSSION...Sawtelle
AVIATION...Percha
FIRE WEATHER...Percha/Hopper/MO/CB
Excessive Heat, Central Phoenix
- When
- September 22, 12:00 AM MST to September 23, 11:59 PM MST
- Where
- Central Phoenix forecast zone
- Deaths
- 1 direct, 2 indirect
- Reported by
- County Official
- Coordinates
- 33.349, -112.491 (the zone’s center; the record gives no point)
Dangerous heat continued into the latter half of September, leading to several additional fatalities for the month. Phoenix Sky Harbor airport recorded temperatures getting up to 105 degrees on September 28th, resulting in abnormally hot conditions. According to Maricopa County Department of Public Health, there were 4 heat-associated deaths (2 direct and 2 indirect) that occurred during this time. Unfortunately, the Maricopa County Department of Health was unable to provide details such as age, gender or circumstances regarding the deaths.
Excessive Heat, East Valley
- When
- September 27, 12:00 AM MST to 11:59 PM MST
- Where
- East Valley forecast zone
- Deaths
- 1 direct, 0 indirect
- Reported by
- County Official
- Coordinates
- 33.349, -112.491 (the zone’s center; the record gives no point)
Dangerous heat continued into the latter half of September, leading to several additional fatalities for the month. Phoenix Sky Harbor airport recorded temperatures getting up to 105 degrees on September 28th, resulting in abnormally hot conditions. According to Maricopa County Department of Public Health, there were 4 heat-associated deaths (2 direct and 2 indirect) that occurred during this time. Unfortunately, the Maricopa County Department of Health was unable to provide details such as age, gender or circumstances regarding the deaths.
- Excessive Heat
- Heat at or above the local excessive heat warning criteria, or heat that caused deaths.
After NWS Directive 10-1605, the rules offices file Storm Data by.
- Heat in Arizona, September 22 to 23, 20182 deaths · 2 events
- Flash Flooding and Flood in Virginia, September 22 to 23, 2018$2.9 million · 19 events
- Flash Flooding and Flood in Texas, September 22, 2018$250,000 · 12 events
- Wildfire in Idaho, September 22 to 25, 2018$100,000 · 1 event
- Flash Flooding in West Virginia, September 22 to 23, 2018$75,000 · 2 events
- Flash Flooding in Louisiana, September 22, 201817 events
- Waterspouts in South Atlantic Coastal Waters, September 22, 20182 events
- Flash Flood and Flood in Kentucky, September 22, 20182 events
- High Wind in Texas, September 22, 20181 event
- Dense Fog in California, September 22, 20181 event
- Wildfire in Idaho, September 22 to 27, 20181 event
- Dust Devil in Nevada, September 22, 2018$10,000 · 1 event
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: 863879, 863880.