DROUGHT INDICATORS - October 1998

Division 1 - Indicators through September show the bottom extent of "normal" with a drying trend. PDSI weekly averages in October are running between -1 and -2.

Division 2 - Indicators through September show the dry side of normal. There has been little change in October with the PDSI running zero to -1.

Division 3 - Warning category (PDSI) and Emergency category with respect to the SPI (-1.50 to -1.99 range). Greenness map accurately shows how the northern part of division 3 has been wetter than the southern part. Weekly PDSI shows some improvement during October.

Division 4 - Normal

Division 5 - Normal

Division 6 - Reached the Advisory (incipient drought) stage in September. Weekly PDSI shows a continued drying with the index down to -2 on October 10. SPI is in the -1.0 to -1.49 range.

Division 7 - Emergency stage. Weekly PDSI shows little change, with index hovering around -4. SPI is in the -1.5 to -1.99 range.

Division 8 - Reached the Advisory (incipient drought) stage in September. Drying has continued in October, with the weekly PDSI below -2. SPI is in the -1.0 to -1.49 range.

September/October Precipitation

Approximately 90 percent of the state of New Mexico received below normal precipitation in September. Much of the Rio Grande Valley south of Taos received less than 25 percent of the normal precipitation, and some spots were less than 10 percent of normal. Much of the eastern plains received less than 50 percent of normal precipitation, with some spots as low as 5 and 10 percent. The northern portion of Division 2 fared better than the remainder of the state, with above normal precipitation. The area between Eagle Nest and Black Lake received about 200 percent of the normal September precipitation.

Forecasts

Short Term - After a dry nineteen days, the combination of a slow moving dynamic low pressure system over the Southwest U.S. and remnants of Hurricane Madeline has been bringing some rainfall to New Mexico. The first significant winter storm of the season should affect parts of New Mexico the week of October 26. With the present pattern, most areas of New Mexico should see above normal precipitation the last week of October.

Long Term - The latest long-range forecast from the climate prediction center (issued Oct. 15, 1998) shows greater than normal probabilities of above normal temperatures and below normal precipitation for New Mexico for the remainder of autumn 1998 through the spring of 1999. This is consistent with the forecasts issued for the time period over the past few months. This forecast is also very consistent with the development of a moderate La Nina. Historical data, while only including 8 to 10 La Ninas of the century, show that winter precipitation in New Mexico frequently averages on about 50 to 60 percent of normal, during these events.

As of the end of August, New Mexico climate divisions 3 and 7 were in the Warning category. Division 3 had experienced a monthly average PDSI between -2 and -3 for two consecutive months, wile the monthly PDSI for Division 7 had been -2 and -3 for three consecutive months. Unless a widespread heavy rain event occurs before the end of September, Division 7 will be in the Emergency category by the end of the month.

Summer Precipitation: For the June through August period, the statewide average precipitation for New Mexico was 105 percent of normal. Generally, most of the area north and west of a line from Raton-Las Vegas-Ruidoso-Orogrande had normal to above normal summer precipitation. Most of the area south and east of that line had a dry summer. Lowest (relative to normal) summer precipitation was in the extreme east and southeast, where the worst drought conditions had already developed. Much of the area southeast of a line from Carlsbad to Clovis received less than 50 percent of the normal summer rainfall.

Reservoir and General Agriculture Conditions: Major reservoirs throughout New Mexico remain at 95 percent of the 15 year mean. Reservoir levels along the San Juan River and Rio Grande River decreased from last month, mainly due to heavy crop irrigation. The weekly Ag. Update is reporting similar drying conditions statewide. Soil moisture statewide is reported mostly short to very short. Crop conditions are in mostly good to fair condition with the exception of sorghum which is mostly in poor condition as a result of the dry summer in eastern New Mexico.

Weekly Trends of PDSI: The entire state of New Mexico is in a drying trend. By September 21 (using preliminary numbers), the weekly PDSI was below zero in all but two divisions (4 and 5). A four-week running average of -1.4 places Division 8 in the Advisory stage at this time.

Forecasts: The latest 13 month forecast from the Climate Prediction Center indicates the likelihood of below-normal precipitation and above-normal temperatures for New Mexico through the coming winter and spring 1999 seasons. This is based mainly on the development and intensification of La Nina conditions. This forecast is also consistent with the previous forecasts for the upcoming winter and spring.

Streamflow Conditions/Other Indicators: Streamflow conditions on October 26, 1998 were indicative of other indicators. The Pecos River Basin stream flows were running 79% of the long-term mean flow, while the Pecos River Basin was 61 % of the long-term mean flow. All other basins were near average to above average, particularly the San Juan River Basin which was

273 % of the long-term mean flow. According to USGS, these conditions as of Oct. 26, 1998 are indicative of the daily averages for October.

Sno-tel sights are reporting near average precipitation throughout the state with the exception of the Gila and Mimbres areas which are approximately 50% of normal.

The Weekly Ag Update is reporting mostly very short to short soil moisture conditions throughout the state. The southeastern and southwestern parts of New Mexico are reporting the driest conditions at this time.