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October 2002 - Report and Summary

The month of October 2002 saw near normal temperatures and near normal precipitation. The month was characterized by an upper air pattern more common in the middle of the cool season instead of at its beginning. For much of the month, an upper air trough was over Central and Eastern North America. This permitted cool air masses to slide southward, and be overrun by moist air brought in from the Gulf of Mexico. At the same time, disturbances in the southwesterly flow aloft generated rainfall. For nine days, between the 20th and 28th, the sun did not shine. Such a pattern is typical in El Nino years. A moderate El Nino Southern Oscillation (ENSO) set up over the East Central Equatorial Pacific Ocean in late-Spring, and above normal sea-surface temperatures there continued last month. In comparison with October 2001, last month was 2.2 deg. warmer, and 2.97 inches wetter.

Year-to-date rainfall through October 31 was 11.25 inches less in 2002 than through the same date in 2001. The thirty-day outlook for October 2002 had called for near normal temperatures and near normal precipitation.

The week September 29-October 5 saw temperatures five degrees warmer than normal, and no rainfall. For most of the week, upper air high pressure remained in control of the area's weather. This was responsible for the very warm temperatures. The approach of Hurricane Lili to the Louisiana Coast on the 1st and 2nd helped keep temperatures up. On the 4th, near-record high readings in the middle 90s were observed due to compressional heating ahead of a weak cold front, which went through the area on the evening of the 4th. The week's average temperature was 76.9 deg., which was 4.2 deg. warmer than the previous week, and 13.6 deg. warmer than the same week in 2001.

The week october 6-12 was one degree cooler than normal, and rainfall was about 300 percent of normal. Tropical Maritime air continued over the region early in the week. Between the 7th and 9th, an upper air low pressure feature crossed. This produced general and significant rainfall. Amounts varied widely from half an inch or so along the Texas/Louisiana border to as much as seven inches along Red River. A weak cold front moved into the region on the 11th, but it was quickly replaced by Tropical Maritime air on the 12th--which brought rapid warming. The week's average temperature was 68.8 deg., with rainfall totalling 2.49 inches. The week was 8.1 deg. cooler than the previous week. Compared with 2001, the week was 3.0 deg. warmer, and 0.20 inch wetter. During the week, an upper air trough had established itself over Central and Eastern North America. This is the typical cool-season position for this trough. Upper air high pressure was over Western North America, with a second ridge over the Gulf of Mexico and Caribbean. This ridge built into the region early in the week, and again briefly at late-week.

The week October 13-19 saw temperatures five degrees cooler than normal, and near normal rainfall. Polar Continental air built into the region on the 13th, and remained until briefly replaced by Tropical Maritime air on the 18th. This was ahead of a powerful upper air storm which crossed on the 18th/19th, and produced generous rainfall. North of the IH-30 Corridor, rainfall amounts of more than six inches occurred on those days. Earlier in the week, an upper air storm had crossed which brought light rain on the 14th. A reinforcing cool air surge reached the region on the 15th. The Polar Vortex was over Southeastern Canada during most of the week, which spun cold fronts into the region. The rain event of the late-week period developed under a crossing upper air low. Severe weather occurred over Kaufman, Smith, and Van Zandt Counties on the early-morning of the 19th. The week's average temperature was 62.0 deg., and total rainfall was 1.28 inches. This temperature was 6.8 deg. cooler than the previous week. Compared with the same week in 2001, the week was 0.3 deg. warmer, and 1.20 inches wetter.

The week October 20-26 saw temperatures near normal and near normal precipitation. The sun did not shine during the week. An upper air low over the Southwestern United States and upper air high pressure over the Southeastern United States caused winds aloft to be southwesterly. This brought disturbances, which caused rain on the 22nd and 25th. A cold front on the night of the 19th/20th with another on the 25th kept a shallow cool air layer over the region. This was overrun by warm and moist air just above the surface, which caused the overcast. Temperatures during the week were within a narrow range, as the cloudiness held down daytime high readings and held up nighttime low readings. The week's average temperature was 64.6 deg., which was 2.6 deg. warmer than the previous week. Rainfall was 0.90 inch. Compared with the same week in 2001, the week was 3.3 deg. cooler, and 0.90 in. wetter. There had been no rainfall during the week in 2001.

The final five days of the month were also cool. Skies finally cleared on the 29th, but cloudiness returned on the afternoon of the 30th with another cold front. A front on the 29th had been responsible for the brief clearing. Cloudiness persisted from mid-day on the 30th through the end of the month.

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.

October 2002

MX MN OBS PCPN REMARKS

October 2002, RECORDS AND SUMMARY:

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