A Seasonal Probabilistic Outlook for Tornadoes (SPOTter) in the Contiguous U.S.

This new study accepted in Monthly Weather Review (Lee et al., 2021) presents an experimental model for Seasonal Probabilistic Outlook for Tornadoes (SPOTter) in the contiguous U.S. for March, April and May, and evaluates its forecast skill. This forecast model uses the leading empirical orthogonal function modes of regional variability in tornadic environmental parameters (i.e.,... Continue Reading →

Why does the Arctic temperature rise faster in the cold season?

The Arctic warming response to increasing greenhouse gas is substantially greater than the rest of the globe. It has been suggested that this phenomenon, commonly referred to as Arctic amplification, and its peak in boreal fall and winter result primarily from the so-called lapse-rate feedback, which is associated with the vertical structure of tropospheric warming,... Continue Reading →

What caused the abrupt reduction of the South Indian Ocean heat & sea level in 2014–2016 and the ensuing quick recovery?

A decade-long increase of the basin-wide sea level and heat content in the subtropical southern Indian Ocean (SIO) during 2004–2013 ended abruptly, immediately following the onset of the strong 2014–2016 El Niño. Interestingly, this unprecedented drop of the SIO heat quickly recovered during the weak 2017–2018 La Niña. A study recently published in Science Advances... Continue Reading →

Co-variability of Pacific‐Atlantic SST contrast, Caribbean Sea tropical rainfall and U.S. summer to fall rainfall variability

In the U.S., peak summer (June-July) rainfall variability, especially east of the Rockies, is largely linked to North Atlantic sea surface temperature (SST) anomalies and associated variations in the Bermuda High. However, these well-established relationships almost completely break down in late summer to mid fall (August-October). Thus, operational seasonal forecast models have generally low skill... Continue Reading →

MJO-induced drying air across Central America may be a precursor to active weeks of U.S. tornadoes

The National Oceanic and Atmospheric Administration’s Storm Prediction Center (NOAA SPC) provides one- to eight-day severe weather forecast for the U.S. that includes tornado watch. To extend the current severe weather forecast beyond eight days to 2 - 4 weeks (i.e., subseasonal time scale), many studies have looked into the Madden-Julian Oscillation (MJO), a patch... Continue Reading →

Spatiotemporal diversity of Atlantic Niño and associated rainfall variability over West Africa and South America

A phenomenon known as Atlantic Niño is characterized by the appearance of warm sea surface temperature anomalies (SSTAs) in the eastern equatorial Atlantic in northern summer. When it attains its full strength, it increases rainfall and the frequency of extreme flooding over the West African countries bordering the Gulf of Guinea and in northeastern South... Continue Reading →

Pantropical response to global warming and the emergence of a La Nina-like mean state trend

During the past century, the tropical Pacific Ocean has warmed significantly less than the other tropical oceans  in response to increasing greenhouse gases (GHGs). This La Nina-like warming trend in the observations is in stark contrast to the El Nino-like warming trend projected by the Coupled Model Intercomparison Project (CMIP) models for both the 20th... Continue Reading →

North Atlantic Ocean gyre circulation dictates the interannual sea level variability along the U.S. Southeast and Gulf Coasts

Interannual and longer time-scale sea level changes are relatively small amplitude. However,  they can provide background conditions favorable for the occurrence of extreme sea levels that represent a threat for coastal communities, especially in low-lying and flood-vulnerable regions. A new study accepted in Geophysical Research Letters identified the dominant mode of the ocean gyre-scale sea surface height... Continue Reading →

Extreme U.S. Great Plains heat waves are linked to East Asian Monsoon

Heat waves are the leading weather‐related cause of death in the U.S. For example, the most recent U.S. extreme heat waves that occurred over the Great Plains in 2011 and 2012 caused 362 deaths. These events are unusual and largely unpredictable beyond the synoptic time scale. However, their number and severity have increased and are projected... Continue Reading →

Co-variability of salinity, nutrients and coastal currents in the northern Gulf of Mexico and its impact on plankton biomass

The northern Gulf of Mexico (GoM) is a region strongly influenced by river discharges of freshwater and nutrients, which promote a highly productive coastal ecosystem that host commercially valuable marine species. A new study appeared in Scientific Report utilized a regional ocean-biogeochemical model and observations to show that El Niño - Southern Oscillation (ENSO) is a main... Continue Reading →

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