ABRFC Drought Briefing(05/22/2014)
......Exceptional and Extreme Drought expanding rapidly..........Some relief on the way?.........
The dry pattern we've been plagued with for the past several months mostly continued during the past few weeks. Rainfall deficits across much of the region are at historic levels. Extreme and Exceptional Drought that has been in place across parts of Northwest Texas and Southwest Oklahoma is expanding notrtheastward into much of Central Oklahoma. However, a bit of relief could be on the way as a wet pattern appears to be materializing for at least the next several days. Some of the driest areas could see rainfall measured in inches instead of hundredths during the next week.
Figure 1 shows the past 30 days of precipitation across the ABRFC area. The heaviest precipitation was in the higher terrain of Colorado, Southeast Oklahoma, and Arkansas. The heavier rainfall across Arkansas actually caused a little bit of river flooding. Most of the other areas within our basin saw precipitation during the past 30 days, but not close to what is considered seasonal. Figure 2 shows the departure from normal precipitation across the ABRFC at the 30, 60, 90, and 180 day timescales. This animation shows the tremendous dryness that's overtaken much of the region during the past 6 months. Almost all areas of the ABRFC are below normal for all 4 of these timescales. Many areas have seen their driest or near their driest first 4 months of the year in recorded history. Many areas from western Oklahoma to eastern New Mexico received less than 25% of their normal rainfall during the past 6 months. This is in addition to nearly continuous ongoing severe to exceptional drought in the same areas since late 2010. To say the situation is dire is an understatement. Figure 3 shows a six week animation of the drought designations from the U.S. Drought Monitor. It's very easy to see the continued expansion of all levels of drought across our area. What is especially troubling is the rapid spatial expansion of the D3 and D4 areas.
Figure 4 shows the latest Drought Severity Index map based on the Long Term Palmer Index from the Climate Prediction Center (CPC). Since the product is based on dry conditions for very long timescales, the extreme nature of the current situation isn't readily depicted by this product. However, the deterioration of drought conditions does show up. The CPC also generates the U.S. Seasonal Drought Outlook (Figure 5) once per month. Unfortunately, drought conditions are forecast to persist or worsen across much of the drought areas of the basin into Summer, although near normal rainfall across the eastern half of Oklahoma could ease the expanding drought there slightly. Although this product doesn't show it, some areas currently in drought could receive heavy rainfall from the expected wet pattern over the region during the next several days. Small areas of improvement in the drought designation are possible, depending on how much rain falls. The CPC's 3-month Precipitation Outlook is shown in Figure 6. The forecast for the Summer months is for an enhanced Summer Monsoon season across the Southern Rocky Mountains. So there is a slightly increased chance for above normal precipitation along our far western boundary. Otherwise, the outlook calls for equal chances of near, above, or below normal precipitation across much the ABRFC for the next 3 months. On the Arkansas River, all reservoirs in eastern Oklahoma are near their normal pool elevations (Figure 7). A few reservoirs in the Red River Basin (Figure 8) still have below normal pool elevations, with the largest lake in the system (Denison) significantly below normal. This is expected, since much of the inflow area for this lake has been in the grips of an extreme, multi-year drought. Real-time river gage data from the USGS can be linked from Figure 9.
To view charts of the running precipitation total for 2014 compared to normal and for previous years back to 2006 for several locations across the ABRFC click here.
ABRFC is now producing experimental soil moisture graphics using parameters from our hydrologic distributed model. Click here.
Fig. 3: 6-week animation of previous Drought Monitor maps. Click here for direct link.
Fig. 4 CPC's Long-term Drought Severity Index. Click here for direct link.
Fig. 5: CPC Seasonal Drought Outlook. Click here for direct link.
Fig. 6: CPC 3-month Precipitation Outlook. Click here for direct link.
Fig. 9: Real-time USGS Streamflow Map. Click here for direct link.
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