LOS ANGELES (AP) – Northwestern California has slipped deeper into drought while Southern California continued to show benefits from an exceptionally wet spring. U.S. Drought Monitor data released Thursday shows extreme drought now covers Del Norte County and parts of adjacent Siskiyou, Humboldt and Trinity counties. The monitor also shows a swath of counties extending south to the San Francisco Bay Area have changed from moderate to severe drought. Most of the rest of northern and central California is a mix moderate drought or abnormal dryness. All of Southern California remains free of all dryness but the region is entering its first heat wave of the year.