Skip Navigation Links 
NOAA logo - Click to go to the NOAA home page National Weather Service   NWS logo - Click to go to the NWS home page
Climate Prediction Center


April - June 2007


Latest Seasonal Assessment - With the dry season approaching, prospects for significant relief across California and the Southwest have diminished, and drought will persist or intensify during the spring. Much of southern California has just experienced its driest autumn-winter in at least 112 years. There is also the potential for drought expansion into Nevada, Utah, western Colorado, and western New Mexico. Persisting drought is on tap for Wyoming and western South Dakota, but many other areas in the northern Plains should see some improvement. Although the severe to extreme drought area over northern Minnesota is expected to see improving conditions, it is unlikely there will be enough rain or snow to end the long-term drought there. Some improvement is anticipated over the lingering drought areas in Oklahoma and Texas, as storms are forecast to dump above-normal rainfall on the Plains during the second half of March. The drought area extending from eastern Tennessee into Mississippi should see some improvement. The odds favor normal to below-normal rainfall across the Florida Peninsula through April, a relatively dry time of the year, supporting drought persistence or even intensification into at least early spring. Some improvement is likely by June as the thunderstorm season gets underway. Elsewhere, drought affecting parts of Puerto Rico will ease. Although drought is not forecast in Alaska, much of the interior has been abnormally dry, so the area bears watching.

Discussion for the Seasonal Drought Outlook

Tools used in the Drought Outlook included the official CPC long-lead precipitation outlook for April-June, the four-month drought termination and amelioration probabilities, various medium and short-range forecasts and models such as the 6-10 day and 8-14 day forecasts), and the soil moisture tools based on the GFS model and the Constructed Analogue on Soil moisture.

The approach of the dry season, the recent and forecast above-normal temperatures, the below-normal snow pack, and a dry monthly and seasonal outlook all result in a confident forecast of persisting or intensifying drought across southern California, western and southern Nevada, and much of Arizona. Going into late March, it would be very difficult to envision enough rain or snow to significantly affect drought prospects this spring. Los Angeles is on track to experience its driest season since records began over 100 years ago, with cumulative rainfall since July one-fifth of normal in mid-March. Thanks to previous winters with good precipitation, reservoirs and groundwater supplies are near normal or better in California, so water supplies are not a major problem. Impacts should be concentrated on wildfire danger, the environment, wildlife, and fisheries. With snow water content well below normal, drought may expand northward into more of Nevada, Utah, western Colorado, and western New Mexico. The CPC precipitation outlook for April-June indicates the odds tilting toward dryness from southern California into Utah and Colorado. The expected above-normal temperatures across the West would worsen the moisture situation. To the north, a number of indicators point to reduced odds for improvement in Wyoming and South Dakota this month compared to the previous month’s forecast. The more pessimistic depiction is supported by the CAS soil moisture forecast for the end of June and the CFS precipitation forecast for April-June and its soil moisture forecasts from March to June. Several other seasonal models indicate a tilt toward dryness extending eastward into southwestern South Dakota, including the UKMET.

Better odds for improvement extend across Montana eastward into northern Minnesota and Wisconsin based on climatology and medium and long range forecasts, including the CFS. The best odds for relief extend from northeastern North Dakota eastward toward the U.P. of Michigan. The expected relief, however, is not likely to be sufficient to end drought in northern Minnesota, where the odds strongly favor continuation of drought at some level through at least June because of the large precipitation deficits that have built up since last summer. The Palmer Drought Index has a 59 percent chance of being in severe drought (-3.0 or lower) in June over north-central Minnesota based on historical data. Looking southward, based on some La Niña analogues and the CAS soil moisture outlook for April and June, there is a chance that conditions from Wyoming to southern Minnesota and Iowa could significantly turn drier, but that is not the consensus forecast at this point.

A stormy pattern is setting up for the last half of March across the Plains states, and this will result in at least short-term improvement for the lingering drought areas in Oklahoma and Texas. Texas saw flooding in mid-March from heavy rains, reducing the drought there. The Drought Outlook depicts limited improvement rather than straight improvement because of some indications for dryness during April-June, as indicated in the CPC seasonal forecast.

There are conflicting forecasts for the drought area extending from eastern Tennessee into Mississippi. Parts of the region will likely turn wetter, and parts may turn drier, with some abundant rains near the start of the forecast period in March. Indicating some improvement appears to be the best compromise at this time, and is consistent with the CFS soil moisture forecasts from March to June. A number of models indicate a greater chance for dryness toward the Gulf Coast, so this area needs to be monitored.

The odds for near-term relief in Florida are slim given that April is one of the drier months there and the last half of March should see normal to below normal rains. The long-lead forecast for April indicates below-normal rainfall for the southern Peninsula. Rainfall typically picks up by late May and is quite substantial during June, so conditions should improve by June, but the dryness could become quite serious before then, so a forecast for persisting drought is appropriate. The fire danger indices are already unusually high across southern Florida, and a La Niña, should it develop, typically favors fire activity. The outlook has become more pessimistic since last month because of the recent drying trend, the imminent start of the dry season, and a few seasonal models indicating drying. The Global Spectral Model, in particular, indicates very dry soil moisture across Florida by early June.

In Puerto Rico, the IRI multi-model forecast for April-June shows a strong wet signal for the island. This, along with the upcoming wet season, results in a relatively confident forecast for improvement. The demise of the El Niño reduces the odds for drought development in Hawaii, as does the recent heavy rainfall over some areas. Alaska’s interior has been abnormally dry, and snow pack is below normal. The CPC seasonal outlook indicates equal chances wet or dry, so drought development is not depicted, but above-normal temperatures are indicated for much of the state in April-June, so dryness could continue or worsen.

NOAA/ National Weather Service
NOAA Center for Weather and Climate Prediction
Climate Prediction Center
5830 University Research Court
College Park, Maryland 20740
Page Author: Climate Prediction Center Internet Team
Page last modified: March 15, 2007
Information Quality
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities