News
Please login to view this content.
06/24/2019, 7:51 pm EDT

North America Season 1-3 Ahead Forecast

Highlight: Changeable Pattern & Less Wet Midwest Executive Summary: The Climate Impact Company season 1-3 ahead forecast for North America is valid for the months of July and August plus SEP/OCT/NOV 2019 and DEC/JAN/FEB 2019-20. The forecast is generated by a SSTA-based analog. The selected SSTA forecast is the NCEP CFS V2. Striking is the changeable climate forecast for the Midwest ranging from drier than normal for July, back to wetter than normal in August and then dry again in autumn. Most probabilistic model forecasts are wet for this region the next several months. However, the CIC constructed analog offers periods of dry relief. The outlook is also quite changeable in the Northwest ranging from a hot mid-summer to cooler weather in August. The Gulf States are wet during autumn and the Northeast winter forecast is cold! Climate discussion: The outlook is based on global SSTA forecasts for JUL/AUG/SEP 2019 through NOV/DEC/JAN 2019-20 by the NCEP CFS V2 model chosen due to best initialization compared to the NMME and GFDL model. The JUL/AUG/SEP 2019 outlook indicates positive phase of the Indian Ocean Dipole (+IOD) and El Nino Modoki (Fig. 1). The North Atlantic is not as warm as many years in the 2000-2019 climatology while a warm northeast Pacific supports the warm phase of the Pacific Decadal Oscillation. The +IOD pattern supports the +PDO which in-turn validates the persistence of a weak El Nino. The +PDO pattern supports western North America warmth and possibly a cold regime in the Northeast this winter. Fig. 1: The NCEP CFS V2 global SSTA forecast for JUL/AUG/SEP 2019 and regional regimes affecting the North America climate are indicated. Fig. 2: The NCEP CFS V2 global SSTA forecast for NOV/DEC/JAN 2019-20 and regional regimes affecting the North America climate are indicated. Outlooks: The outlooks are generated based on analogs which consider the El Nino southern oscillation (ENSO), Pacific decadal oscillation (PDO), Atlantic multi-decadal oscillation (AMO) and Indian Ocean Dipole (IOD) regimes. The analog years extend to the beginning of the current climate cycle (initiated in the mid-to-late 1990’s). Forecasts for July and August are provided plus seasonal forecasts for meteorological autumn and winter ahead. July 2019: Despite a cool start to summer in the West the sharp dryness in the Far Northwest foreshadows returning anomalous heat for mid-summer. In a forecast change albeit low confidence a drier pattern is forecast for the central and northern Great Plains including the Corn Belt. The wet weather shifts to Texas and suppresses mid-summer heat. In the East a wet pattern is indicated just off the coast while the Southeast is dry. The East looks mostly temperate for July. Fig. 3-4: The Climate Impact Company constructed analog temperature and precipitation anomaly climate forecasts for July 2019. August 2019: The Interior Northwest flips cool for late summer. The hot July pattern remains near the Northwest Coast only. Wet weather which could be excessive works its way back into the Midwest States. The Southeast is dry and hot to finish meteorological summer. In the Northeast States warmer and drier than normal weather is expected for late summer. The precipitation outlook does not support any tropical cyclone activity near the U.S. coastline. Fig. 5-6: The Climate Impact Company constructed analog temperature and precipitation anomaly climate forecasts for August 2019. SEP/OCT/NOV 2019: The outlook for autumn is a return to mild conditions across the Northwest U.S. and some of that warmth frequently extends to the northern Great Plains. The Corn Belt is drier than normal for autumn. The Gulf States to Tennessee Valley are wet possibly related to mid-to-late season tropical cyclone activity. The Mid-Atlantic States are wet during autumn. Fig. 7-8: The Climate Impact Company constructed analog temperature and precipitation anomaly climate forecasts for SEP/OCT/NOV 2019. DEC/JAN/FEB 2019-20: The preliminary outlook for next winter is a cold and snowy regime for the Northeast U.S. with the chill extending down the East Coast into the southeastern states. A wet regime in the Southwest while much of the West is warm. The Southeast States are drier than normal. Fig. 9-10: The Climate Impact Company constructed analog temperature and precipitation anomaly climate forecasts for DEC/JAN/FEB 2019-20.