An official website of the United States government
Abstract Hurricane Hilary brought extensive, record‐breaking precipitation to the Southwest United States in August 2023. Although tropical cyclones (TCs) are uncommon in this region, they can cause substantial damage, primarily through flooding. However, heat extremes associated with these TCs are understudied and could have significant impacts in populated coastal areas. This study examines the conditions that promoted the occurrence of 42 north‐reaching, northeastern Pacific TCs and quantifies how local temperatures responded to these storms. Using composite analysis, we find that there is significant warming along the coastal region of Southern California preceding a TC, particularly for storms that remain offshore. Three main mechanisms contribute to this warming pattern—adiabatic compression associated with downslope winds, warm air advection by the TC itself, and suppression of coastal upwelling. These compound heatwave‐TC events are an overlooked impact of TCs that will likely become more important as the climate warms.
more »
« less
This content will become publicly available on June 28, 2027
Contribution of Tropical Cyclones to Hourly Precipitation Extremes in the Contiguous United States
Abstract Tropical cyclones (TCs) are major drivers of contiguous United States (CONUS) flooding, yet their contribution to hourly precipitation extremes remains poorly quantified. Here we link observations from 420 gauges (1980–2024) with TC track data to attribute extreme hourly precipitation to both local and remote TCs. Remote TC contributions are identified via atmospheric river (AR) objects using the TempestExtremes framework applied to a global AR database. We identify 254 TCs that contributed to extreme hourly precipitation, affecting 76% of stations. While local contributions from Atlantic TCs are prevalent in eastern CONUS, remote influences from Pacific TCs contribute to precipitation extremes in the rest of CONUS. The number of TCs resulting in extreme hourly precipitation has increased significantly in northeast and southeast CONUS since 1980. These results reveal that TC‐linked moisture represents a contributor to short‐duration precipitation extremes across a broader area of CONUS than previously recognized.
more »
« less
- Award ID(s):
- 2403765
- PAR ID:
- 10712899
- Publisher / Repository:
- American Geophysical Union
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 53
- Issue:
- 12
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Global mean and extreme tropical cyclone (TC) precipitation have been increasing over the past few decades and are expected to continue to increase into the future due to climate change. Most projections of future TC precipitation use climate models with grid spacings of 25–100 km, which are too coarse to resolve the convective structures and small‐scale precipitation processes within TCs. This work uses convection‐permitting Weather Research and Forecasting model simulations to investigate how precipitation and precipitation processes change in the inner core (IC) and outer rainbands (OR) of TCs in response to sea surface temperature (SST) warming. The simulations are idealized, with single TCs initialized from weak vortices over domain‐constant SSTs. In these simulations, TC intensity and IC precipitation greatly increase with SST warming while OR precipitation increases slightly. A greater area in the IC is occupied by deep convection more frequently in the warmer simulations, while the deep convective activity remains relatively constant with warming in the TC OR. Mixing ratios of hydrometeors and cloud ice increase with warming in both the IC and OR, while the TCs' vertical circulations deepen, melting levels rise, and mean upward velocities strengthen. This work demonstrates how analysis of three‐dimensional storm structures can provide insight into processes that change TC precipitation in different regions of the storm, and future work will include applying this analysis to more realistic convection‐permitting simulations.more » « less
-
The impacts of inland flooding caused by tropical cyclones (TCs), including loss of life, infrastructure disruption, and alteration of natural landscapes, have increased over recent decades. While these impacts are well documented, changes in TC precipitation extremes—the proximate cause of such inland flooding—have been more difficult to detect. Here, we present a latewood tree-ring–based record of seasonal (June 1 through October 15) TC precipitation sums (ΣTCP) from the region in North America that receives the most ΣTCP: coastal North and South Carolina. Our 319-y-long ΣTCP reconstruction reveals that ΣTCP extremes (≥0.95 quantile) have increased by 2 to 4 mm/decade since 1700 CE, with most of the increase occurring in the last 60 y. Consistent with the hypothesis that TCs are moving slower under anthropogenic climate change, we show that seasonal ΣTCP along the US East Coast are positively related to seasonal average TC duration and TC translation speed.more » « less
-
Abstract A critical task to better quantify changes in precipitation (P) mean and extreme statistics due to global warming is to gain insights into the underlying physical generating mechanisms (GMs). Here, the dominant GMs associated with daily P recorded at 2861 gauges in the Conterminous United States from 1980 to 2018 were identified from atmospheric reanalyses and publicly available datasets. The GMs include fronts (FRT), extratropical cyclones (ETC), atmospheric rivers (AR), tropical cyclones (TC), and North American Monsoon (NAM). Climatologies of the GM occurrences were developed for the nonzero P (NZP) and annual P maxima (APM) samples, characterizing the marginal and extreme P distributions, respectively. FRT is everywhere the most frequent (45-75%) GM of NZP followed by ETC (12-33%). The FRT contribution declines for APM (19-66%), which are dominated by AR (50-65%) in western regions and affected by TC (10-18%) in southern and eastern regions. The GM frequencies exhibit trends with the same signs over large regions, which are not statistically significant except for an increase in FRT (TC) frequency in the Northeast (central region). Two-sample tests showed well-defined spatial patterns with regions where (1) both the marginal and extreme P distributions of the two dominant GMs likely belong to different statistical populations, and (2) only the marginal or the extreme distributions could be considered statistically different. These results were interpreted throughL-moments and parametric distributions that adequately model NZP and APM frequency. This work provides useful insights to incorporate mixed populations and nonstationarity in P frequency analyses.more » « less
-
Abstract This study uses a recently developed airborne Doppler radar database to explore how vortex misalignment is related to tropical cyclone (TC) precipitation structure and intensity change. It is found that for relatively weak TCs, defined here as storms with a peak 10-m wind of 65 kt (1 kt = 0.51 m s−1) or less, the magnitude of vortex tilt is closely linked to the rate of subsequent TC intensity change, especially over the next 12–36 h. In strong TCs, defined as storms with a peak 10-m wind greater than 65 kt, vortex tilt magnitude is only weakly correlated with TC intensity change. Based on these findings, this study focuses on how vortex tilt is related to TC precipitation structure and intensity change in weak TCs. To illustrate how the TC precipitation structure is related to the magnitude of vortex misalignment, weak TCs are divided into two groups: small-tilt and large-tilt TCs. In large-tilt TCs, storms display a relatively large radius of maximum wind, the precipitation structure is asymmetric, and convection occurs more frequently near the midtropospheric TC center than the lower-tropospheric TC center. Alternatively, small-tilt TCs exhibit a greater areal coverage of precipitation inward of a relatively small radius of maximum wind. Greater rates of TC intensification, including rapid intensification, are shown to occur preferentially for TCs with greater vertical alignment and storms in relatively favorable environments. Significance StatementAccurately predicting tropical cyclone (TC) intensity change is challenging. This is particularly true for storms that undergo rapid intensity changes. Recent numerical modeling studies have suggested that vortex vertical alignment commonly precedes the onset of rapid intensification; however, this consensus is not unanimous. Until now, there has not been a systematic observational analysis of the relationship between vortex misalignment and TC intensity change. This study addresses this gap using a recently developed airborne radar database. We show that the degree of vortex misalignment is a useful predictor for TC intensity change, but primarily for weak storms. In these cases, more aligned TCs exhibit precipitation patterns that favor greater intensification rates. Future work should explore the causes of changes in vortex alignment.more » « less
