WEATHER ARCHIVES

April 2011

Report and Summary

Tyler, Texas
April 2011
by Robert K. Peters, Ph.D.
National Weather Service Cooperating Observer

The month of "April 2011 was much warmer than normal, and saw near normal rainfall. It was, in fact, the sixth warmest April on record. Compared with April 2010, the month was 4.3 deg. Warmer, and 2.65 inches wetter.

Year-to-date rainfall at momth's end was nearly identical in 2010 and 2011: 11.88 inches in the former and 11.35 inches in the latter. The thirty-day outlook for April 2011 had called for near normal temperatures and near normal precipitation.

The month began warm and breezy under upper air high pressure. A cold front and storm system crossing on the morning of the 4th brought thunderstorms some of which were severe and rainfall of between one and two inches.

Temperatures cooled through the morning of the 6th, but warmed again thereafter under returning upper air high pressure. Strong winds blew on the 6th and 8th as low pressure deepened along the lee slope of the Rocky Mountains, and the eastward-moving surface high responsible for the cool temperatures of the previous two days shifted away from the region.

The year's first 90-degree high temperature came on the 10th as upper air high pressure controlled until a cold front came through on the morning of the 11th. This caused thunderstorms a few of which were severe near the Louisiana border. Temperatures cooled for a couple of days, warming again on the 13th with strong winds through the 15th. Another cold front arrived then, bringing more thunderstorms some of which were severe north and east of Tyler.

Temperatures cooled until the surface high pressure ridge, associated with that cold front, shifted east on the 17th. This resulted in gusty south winds beginning that afternoon.

A crossing upper air disturbance on the night of the 19th brought more severe weather north and east of Tyler, with rainfall occurring there. Tyler missed out.

A cold front made a brief appearance from the evening of the 20th through the morning of the 21st. Otherwise, Tropical Maritime air covered the region. Conditions were warm and windy most days between the 21st and 25th. An upper air storm and attendant cold front crossed during the 25th and 26th. This brought two rounds of severe weather, with a tornado outbreak on the evening of the 26th.

There was property damage in Van Zandt County. Three tornadoes crossed Smith County one from southwest of Lindale to near Hawkins, a second in northwest Tyler, and ahe third from southeast of Tyler to near Kilgore.

Neither of these touched down in Smith County, though there was considerable wind damage. Cooler temperatures followed, until another warming trend commenced on the 29th.

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

The reporting period for temperatures 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. The reporting period for precipitation is for the twenty-four hours ending at noon GMT--6 a.m. CST and 7 a.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.

APRIL 2011

DY MX MN OBS PCPN REMARKS

01 87 48 81 F, H
02 85 57 78 tr.
03 82 66 77
04 73 46 60 1.61 T, F, A, Morning low 72, Daytime High 72
05 70 38 66
06 82 49 78
07 61 80 77
08 88 69 84
09 89R 65 84
10 90 67 85
11 77 53 71 0.19 T, F, PCPN 0900-1200, Morning low 64
12 79 46 75
13 81 49 77
14 84 63 79
15 74 58 69 0.02 T, PCPN 0600-0700
16 75 48 69
17 83 47 79
18 88 66 85
19 92 72 87
20 88 61 78 F, MORNING LOW 71
21 88 61 84 F
22 92R 71R 87
23 87 72 83
24 90 69
25 82 65 75 0.23 T, F, PCPN 2100-2200 Morning Low 71
26 83 62 70 0.02
27 72 55 67 1.43 F, T, PCPN 0000-0200, 0900-1000 Morning Low 65
28 77 47 74
29 83 50 79
30 85 64 81

APRIL 2011, RECORDS AND SUMMARY:

9TH EQUALLED RECORD HIGH MAXIMUM 89, FIRST SET IN 1999;
10TH WARM SEASON BEGINS WITH FIRST 90-DEG. TEMPERATURE;
19TH RECORD HIGH MINIMUM 72, PREVIOUS RECORD 69 IN 2002;
22ND, EQUALLED RECORD HIGH MAXIMUM OF 92, SET FIRST IN 1925;
22ND RECORD HIGH MINIMUM 71, REPLACES 70 FROM 1924, 1944, AND 1963;
26TH TORNADOES 10NW @2310;
27TH TORNADO 3NW @0005;
HIGHEST TEMPERATURE 92 ON THE 19TH AND 22ND,
LOWEST TEMPERATURE 38 ON THE 5TH,
AVERAGE MAXIMUM 82.9 F.,
AVERAGE MINIMUM 58.2 F.,
AVERAGE TEMPERATURE 70.6 F.,
4.0 DEG. WARMER THAN NORMAL.
27 HEATING DEGREE DAYS,
51.9 PERCENT OF NORMAL HEATING DEGREE DAYS.
200 COOLING DEGREE DAYS,
204.1 PERCENT OF NORMAL COOLING DEGREE-DAYS;
TOTAL PRECIPITATION 3.50 IN.,
0.20 IN. LESS THAN MONTHLY NORMAL.
94.6 PERCENT OF NORMAL MONTHLY PRECIPITATION.
YEAR-TO-DATE PRECIPITATION 11.35 IN.,
3.38 IN. LESS THAN NORMAL YEAR-TO-DATE PRECIPITATION,
77.1 PERCENT OF NORMAL YEAR-TO-DATE PRECIPITATION;
5 DAYS ON WHICH THUNDERSTORMS OCCURRED;
5 DAYS ON WHICH MEASURABLE PRECIPITATION OCCURRED;
7 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED TO BETWEEN 1/2 AND 6 MILES BY FOG, SMOKE, OR HAZE;
0 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED TO 1/4 MILE OR LESS BY FOG;
0 DAYS ON WHICH THE VISIBILITY WAS RESTRICTED BY DUST OR BLOWING DUST;
1 DAYS ON WHICH FROZEN PRECIPITATION WAS OBSERVED;
0 IN. TOTAL SNOWFALL.
4 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.
2155 SEASON-TO-DATE HEATING DEGREE DAYS,
PERCENTAGE OF NORMAL SEASON-TO-DATE HEATING DEGREE DAYS: 110.6,
275 YEAR-TO-DATE COOLING DEGREE DAYS.
PERCENTAGE OF NORMAL YEAR-TO-DATE COOLING DEGREE DAYS: 189.7,
PRECIPITATION DURING THE PREVIOUS TWELVE MONTHS 35.37 IN.,
TWELVE-MONTH PRECIPITATION PERCENTAGE 78.1.

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