Probabilistic Evaluation of Tibetan Plateau Mesoscale Vortex on 18 July 2013

Tibetan Plateau (TP) mesoscale vortex (TPMV) was regarded as one of the most important rain bearing systems in China. Previous studies focused on the mechanisms of the TPMV in the viewpoint of deterministic forecast; however, few studies investigate the predictability of the TPMV using the Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Global Ensemble (TIGGE) from the European Center for Medium Range Weather Forecasts (ECWMF). This paper investigates the location and the intensity of the larger-scale synoptic systems that influenced the development of the TPMV and its associated heavy rainfall by correlation and composite analysis. The case study on 18 July 2013 shows that stronger Balkhash Lake ridge, weaker Baikal Lake trough, and weaker western Pacific subtropical high (WPSH) are favorable to formation of TPMV over the Sichuan basin (SCB); otherwise, weaker Balkhash Lake ridge, stronger Baikal Lake trough, and stronger WPSH result in formation of TPMV to west of the SCB slightly. After the initial time, forecast for next 48 h of the geopotential height over the SCB can be viewed as a precursor of the subsequent time-averaged 90–108 h forecast of TPMV. TPMV had critical contributions to the heavy rainfall over the SCB on 18 July 2013.

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The Role of Diurnal Solenoidal Circulation on Propagating Rainfall Episodes near the Eastern Tibetan Plateau

Monthly Weather Review ◽

10.1175/2010mwr3225.1 ◽

2010 ◽

Vol 138 (7) ◽

pp. 2975-2989 ◽

Cited By ~ 34

Author(s):

Hsiao-Ling Huang ◽

Chung-Chieh Wang ◽

George Tai-Jen Chen ◽

Richard E. Carbone

Keyword(s):

Tibetan Plateau ◽

Weather Research And Forecasting ◽

The Tibetan Plateau ◽

Sensitivity Tests ◽

Westerly Winds ◽

Thermally Driven ◽

The Sichuan Basin ◽

Eastern Edge

Abstract In this case study, numerical simulations using the Weather Research and Forecasting model (WRF) are performed for 3–4 May 2002, in which two propagating rain episodes occurred in successive days with close ties to the terrain of the Tibetan Plateau (TP) in East Asia. Through sensitivity tests, it is found that the eastern TP not only facilitated convective development in the afternoon but that the solenoidal circulation between this region and its leeside lowlands (near the Sichuan basin) also contributed to the longevity and farther downstream propagation of the episodes under prevailing westerly winds. Reversed every 12 h, the thermally driven circulation induced ascending motion near the eastern edge of the TP during daytime but over the leeside at night. The episode propagation in this case, as often observed, was in phase with the ascent, from eastern TP in the afternoon to the lee at night, indicating both enhancing and modulating effects of the solenoidal circulation.

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Probabilistic Evaluation of the Dynamics and Prediction of Supertyphoon Megi (2010)

Weather and Forecasting ◽

10.1175/waf-d-12-00121.1 ◽

2013 ◽

Vol 28 (6) ◽

pp. 1562-1577 ◽

Cited By ~ 19

Author(s):

Chuanhai Qian ◽

Fuqing Zhang ◽

Benjamin W. Green ◽

Jin Zhang ◽

Xiaqiong Zhou

Keyword(s):

Early Period ◽

Western Pacific Subtropical High ◽

The Philippines ◽

Subtropical High ◽

Lead Times ◽

Track Forecast ◽

Weather Forecasts ◽

The North ◽

Probabilistic Evaluation ◽

Sharp Turn

Abstract Supertyphoon Megi was the most intense tropical cyclone (TC) of 2010. Megi tracked westward through the western North Pacific and crossed the Philippines on 18 October. Two days later, Megi made a sharp turn to the north, an unusual track change that was not forecast by any of the leading operational centers. This failed forecast was a consequence of exceptionally large uncertainty in the numerical guidance—including the operational ensemble of the European Centre for Medium-Range Weather Forecasts (ECMWF)—at various lead times before the northward turn. This study uses The Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Global Ensemble dataset to examine the uncertainties in the track forecast of the ECMWF operational ensemble. The results show that Megi's sharp turn is sensitive to its own movement in the early period, the size and structure of the storm, the strength and extent of the western Pacific subtropical high, and an approaching eastward-moving midlatitude trough. In particular, a larger TC (in addition to having a stronger beta effect) may lead to a stronger erosion of the southwestern extent of the subtropical high, which will subsequently lead to an earlier and sharper northward turn.

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