Climatology 101: A May without rain or 100° heat

Notable goose eggs for Tucson last month.

May2016Climo

For the 24th time since 1895, the Old Pueblo didn’t record rainfall. This marks the first time since May 2011 that the final monthly rain tally at TIA read 0.00″. While the airport stayed dry, a few metro locations did pick up some rainfall. Amounts were less than 0.10″.

In addition, TIA failed to hit 100° in May for the first time since 2013. We came awfully close to breaking the ice on the 4th, 12th and 14th. Each of those days saw the mercury rise to 99°. As you know by now, Tucson finally recorded its first 100° day on June 2nd. Also worth noting the 11 day stretch of below average highs to finish May. No small feat considering the heat is usually on by Memorial Day.

Here is the detailed climate report for May 2016 and Spring, compiled by the fine folks at NWS Tucson:

Tucsonans experienced another May that had the monthly average high temperature be 2° below normal. The historical record shows that this is the first time that back-to-back Mays recorded the monthly average high temperature being below normal 2° or colder since 1979-1981. The month was pretty much split in half with the first half of the month being above normal while the second half was well below normal. For the first time since 2011 and 24th time overall the official recording site in Tucson recorded ZERO rainfall.
The month started off cooler than normal before strong high pressure aloft brought the first attempt at recording the first triple digit high of 2016. The thermometer fell short on the 4th with a high of 99°. A storm system passing by to the north on the 6th brought cooler temperatures to the region along with strong gusty winds. Wind speeds across the area were mostly between 30 and 45 mph with localized spots, like the airport, recording gusts around 50 mph. Below normal temperatures hung around a few more days before strong high pressure built over the area between the 11th and 15th. Two more attempts at the first triple digit high of 2016 occurred on the 12th and 14th with both days ending up just short at 99°. During this much warmer than normal period, a little moisture crept into the area from the south. This led to isolated showers and thunderstorms on the 13th, but since the lower part of the atmosphere was rather dry, most areas didn’t see any rainfall. Those areas that did measure rainfall had totals that were less than a tenth of an inch.
The first 15 days of the month were about a degree warmer than normal. The remainder of the month was cooler than normal with almost a repeat of 2015 with an extended period of time with below normal high and low temperatures. Over the last 16 days of the month, only one day had an above normal high and five days had above normal low temperatures. The month ended with eleven straight days of below normal high temperatures which is the 4th longest such streak for May dating back to the early 1970s.
Longest stretch of below normal highs for May since early 1970s.
Rank
Year
# of days/Dates
Average
Normal
1)
2015
15 days (12th to 26th)
85.1°
92.6°
2)
1977
13 days (9th to 21st)
81.3°
89.3°
3)
1987
12 days (19th to 30th)
86.3°
92.8°
4T)
2016
11 days (21st to 31st)
89.9°
94.2°
1992
11 days (21st to 31st)
86.4°
93.3°
Normal periods: 1977 (1941-1970); 1987 (1951-1980); 1992 (1961-1990); 2015 & 2016 (1981-2010)
Temperature extremes for the month ranged from a high of 99° on the 4th, 12th & 14th to a low of 53° on the 2nd & 7th. The monthly average temperature of 75.1° is 0.9° below normal and ranks as the 39th warmest on record (tied with 1948). The average high temperature of 89.4° during the first 15 days of the month ranked as the 44th warmest on record, while the average high temperature of 89.9° during the last 16 days of the month ranked as the 35th coolest on record.
May 2016 daily high temperature departure from normal May 2016 daily low temperature departure from normal
Click on image above for larger view
Localized areas received some rain on the 13th otherwise most of the area recorded no rainfall during May, including the airport. Those areas across the metro area that did see rainfall, using several sources likerainlog.org and the Pima County Regional Flood Control District gages, were generally less than a tenth of an inch. For the 24th May on record, and first time since 2011, the official recording spot in Tucson recorded ZERO rainfall.
May 2016 stats
Month
Normal
Departure
Average high temperature
89.6°
91.6°
– 2.0°
Average low temperature
60.6°
60.5°
+ 0.1°
Average temperature
75.1°
76.0°
– 0.9°
Days with highs 100° or greater
0
4
– 4
Rainfall
0.00″
0.23″
– 0.23″

Spring 2016 Spring '16 climate recap for Tucson Arizona
Headlines
13th warmest on record
56th driest on record
11th straight Spring of below normal rainfall
. Click to enlarge
A second straight below normal May countered the warmer than normal March (4th warmest) and April (23rd warmest) to produce the 13th warmest Spring, tied with 2015, on record with an average Spring temperature of 69.6°. Temperature extremes ranged from 99° on May 4th, 12th & 14th to a low of 40° on March 9th & 31st. This is the 4th Spring on record (1943 [40°], 1994 [40°] & 2014 [43°]) that the lowest temperature for the season was NOT below 40°.
Spring 2016 daily high temperature departure from normal Spring 2016 daily low temperature departure from normal
Click on image above for larger view
Precipitation amounts across the metro area for the Spring season, using several sources like rainlog.org, thePima County Regional Flood Control District gages and CoCoRaHS, varied widely and mostly ranged from 0.25″ to 1.50″ with the highest totals across the central and eastern portions of the metro area. Officially, the Tucson International airport recorded 0.82″ which is just under a half an inch below normal and ranks as the56th driest Spring on record. This is also the 11th straight Spring with below normal rainfall at the airport.
Spring 2016 stats
Season
Normal
Departure
Average high temperature
84.3°
82.6°
+ 1.7°
Average low temperature
54.9°
52.9°
+ 2.0°
Average temperature
69.6°
67.7°
+ 1.9°
Days with highs 100° or greater
0
4
– 4
Rainfall
0.82″
1.27″
– 0.45″
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