May 2010

Report and Summary

Tyler, Texas
May 2010
by Robert K. Peters, Ph.D.
National Weather Service Cooperating Observer

May 2010 was the fifth warmest and one of the ten driest months of May on record. The warm and dry trend, which commenced in late-March, accelerated in May. Persistent upper air high pressure and dry soils and vegetation were responsible for the high temperatures. The feedback loop created by dry soils enhanced the low rainfall. Compared with May 2009, the month was 4.5 deg. Warmer, and 0.18 inch drier. Year-to-date rainfall through May 31 was 3.34 inches less in 2010 than in 2009. The thirty-day outlook had called for below normal temperatures and near normal precipitation.

The week April 25-May 1 saw near normal temperatures, and small amounts of rainfall After a cool start to the week, temperatures warmed at mid-week under upper air high pressure. A weak storm system, crossing on the 30th, brought the week's only rainfall. Another disturbance, crossing on the 1st, brought severe weather to the south and east of Tyler. The week's average temperature was 68.0 deg., and rainfall was 0.01 inch. This was 2.5 deg. Warmer than the previous week. Compared with the same week in 2009, the week was 4.0 deg. Cooler, and 0,.44 inch drier.

The week May 2-8 saw near normal temperatures, and precipitation about 10 percent of normal. For much of the week, the air mass was rather dry, meaning mild overnight lows but warm afternoon highs. The first 90-degree high came on the 5th about three days ahead of the median date of May 8. The week's only precipitation came on the night of the 3rd with a crossing upper air system. A stronger cold front came into the region on the 7th, but a capping inversion precluded any rain in Tyler. The week's average temperature was 71.4 deg., which was 3.4 deg. Warmer than the previous week. Precipitation was 0.13 inch. Compared with the same week in 2009, the week was 1.6 deg. Cooler, and 0.64 inch drier.

The week May 9-15 saw temperatures about 4 deg. Above normal, and rainfall about 75 percent of normal. The week began cool, but warmed rapidly beginning the 10th. A storm system crossed on the 14th, with the week's rainfall and a few occurrences of severe weather. The week's average temperature was 75.7 deg., and rainfall was 0.77 inch. The week was 1.7 deg. Warmer and 0.57 inch wetter than the same week in 2009.

The week May 16-22 warmed further, with temperatures still about 4 deg. Above normal and no rainfall. Upper air high pressure was present throughout the week. The average temperature was 77.9 deg., 2.2 deg. Warmer than the previous week. The same week in 2009 was 10.2 deg. Cooler, and 0.23 inch wetter. May 23-29 saw temperatures about 5 deg. Above normal, and still no rainfall. Again, upper air high pressure persisted. The week's average temperature was 80.9 deg., 3.0 deg. Warmer than the previous. This was 8.1 deg. Warmer than the same week in 2009, and 0.14 inch drier. Showers were scattered around the area on the 30th and 31st, with low areal coverage. Upper air high pressure, otherwise, resulted in very warm temperatures.

• KEY TO SYMBOLS:
• A = HAIL
• B = BLOWING
• D = DUST
• F = FOG
• H = HAZE
• IP = SLEET
• K = SMOKE
• L = DRIZZLE
• R = RAIN
• S = SNOW
• T = THUNDERSTORM
• Z = GREENWICH MEAN TIME
• ZL = FREEZING DRIZZLE
• ZR = FREEZING RAIN
• - = LIGHT
• + = HEAVY
• R FOLLOWING A TEMPERATURE OR PRECIPITATION VALUE = RECORD

The reporting period for temperatures, precipitation, and phenomenon on each day is for the twenty-four hours ending at midnight hours GMT--6 p.m. CST and 7 p.m. CDT. All times are given using the twenty-four hour clock, and are expressed in Greenwich Mean Time.

Observations are from NWS Station 41/9207/4 in Tyler, Texas. The term "normal" refers to averages from the standard climatic period 1971-2000.

MAY 2010

• 01 85 66 79 MORNING LOW 68
• 02 81 56 78
• 03 88 51 80
• 04 84 51 81 0.13 PCPN 0400-0700
• 05 92 60 89
• 06 90 62 87
• 07 87 65 81 F
• 08 76 57 72
• 09 71 60 64
• 10 87 64 82 0.01
• 11 92 69 86
• 12 89 70 84
• 13 86 72 82
• 14 89 65 66 0.23 F, T, PCPN 2200-2400 MN 0000-1200 69
• 15 83 63 79 0.53 T, F, +F, PCPN 0000-0100
• 16 88 65 86 F
• 17 91 66 82 F
• 18 86 65 84
• 19 90 69 86 F, H
• 20 83 66 69 Tr., MN 0000-1200 72
• 21 91 65 90
• 22 92 73 89
• 23 93 75 90
• 24 92 71 90 F
• 25 92 68 89 F, H,
• 26 90 69 82 T
• 27 91 67 89 F, H
• 28 94 68 90 F
• 29 94 68 89
• 30 93 68 89 0.26 PCPN 1800-2000
• 31 95 71 93

MAY 2010, RECORDS AND SUMMARY:

• 5TH WARMEST MAY ON RECORD;
• HIGHEST TEMPERATURE 95 ON THE 31ST;
• LOWEST TEMPERATURE 51 ON THE 3RD AND 4TH;
• AVERAGE MAXIMUM 88.2 F.,
• AVERAGE MINIMUM 65.3 F.,
• AVERAGE TEMPERATURE 76.8 F.;
• 3.5 DEG. WARMER THAN NORMAL.
• 0 HEATING DEGREE DAYS,
• 0 PERCENT OF NORMAL HEATING DEGREE DAYS.
• 374 COOLING DEGREE DAYS,
• 139.6 PERCENT OF NORMAL COOLING DEGREE-DAYS;
• TOTAL PRECIPITATION 1.16 IN.,
• 3.30 IN. LESS THAN MONTHLY NORMAL.
• PERCENT OF NO26.0 RMAL MONTHLY PRECIPITATION.
• YEAR-TO-DATE PRECIPITATION 13.04 IN.,
• 6.15 IN. LESS THAN NORMAL YEAR-TO-DATE PRECIPITATION,
• 68.0 PERCENT OF NORMAL YEAR-TO-DATE PRECIPITATION;
• 3 DAYS ON WHICH THUNDERSTORMS OCCURRED;
• 10 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED TO BETWEEN ONE-HALF AND SEVEN MILES BY FOG, SMOKE, OR HAZE;
• 1 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED TO ONE-FOURTH MILE OR LESS
• BY FOG;
• 0 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED BY DUST OR BLOWING DUST;
• 0 DAYS ON WHICH FROZEN PRECIPITATION WAS OBSERVED;
• 0 IN. TOTAL SNOWFALL.
• 5 DAYS ON WHICH MEASURABLE PRECIPITATION OCCURRED.
• 16 DAYS ON WHICH THE MAXIMUM TEMPERATURE REACHED OR EXCEEDED 90 DEG.;
• 0 DAYS ON WHICH THE MAXIMUM TEMPERATURE REACHED OR EXCEEDED 100 DEG.;
• 0 DAYS ON WHICH THE TEMPERATURE FAILED TO RISE ABOVE 32 DEG.
• 0 DAYS ON WHICH THE MINIMUM TEMPERATURE REACHED OR FELL BELOW 32 DEG.
• 2650 SEASON-TO-DATE HEATING DEGREE DAYS,
• PERCENTAGE OF NORMAL SEASON-TO-DATE HEATING DEGREE DAYS: 135.3
• 464 YEAR-TO-DATE COOLING DEGREE DAYS.
• PERCENTAGE OF NORMAL YEAR-TO-DATE COOLING DEGREE DAYS: 112.3;
• PRECIPITATION DURING THE PREVIOUS TWELVE MONTHS 50.37 IN.,
• TWELVE-MONTH PRECIPITATION PERCENTAGE 111.1.

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