The Role of Typhoon Songda (2004) in Producing Distantly Located Heavy Rainfall in Japan*

Abstract

When Typhoon Songda (2004) was located southeast of Okinawa over the western North Pacific during 2-4 September 2004, a heavy rainfall event occurred over southern central Japan and its adjacent seas, more than 1200 km from the typhoon center. The Advanced Research version of the Weather Research and Forecast (WRF-ARW) model was used to investigate the possible remote effects of Typhoon Songda on this heavy precipitation event in Japan. The National Centers for Environmental Prediction (NCEP) global final (FNL) analysis was used to provide both the initial and lateral boundary conditions for the WRF model. The model was initialized at 1800 UTC 2 September and integrated until 1800 UTC 6 September 2004, during which Songda was a supertyphoon. Two primary numerical experiments were performed. In the control experiment, a bogus vortex was inserted into the FNL analysis to enhance the initial storm intensity such that the model typhoon had an intensity that was similar to that observed at the initial time. In the no-typhoon experiment, the vortex associated with Typhoon Songda in the FNL analysis was removed by a smoothing algorithm such that the typhoon signal did not appear at the initial time. As verified against various observations, the control experiment captured reasonably well the evolution of the storm and the spatial distribution and evolution of the precipitation, whereas the remote precipitation in Japan was largely suppressed in the no-typhoon experiment, indicting the significant far-reaching effects of Typhoon Songda. Songda enhanced the remote precipitation in Japan mainly through northward moisture transport into the preconditioned precipitation region by its outer circulation. The orographic forcing of the central mountains in Japan played a small role compared with Typhoon Songda in this extreme precipitation event.

Influence of a Distantly Located Typhoon, a Weak Westerly Trough and Orography on the Intense Rainfall on 14-15 September 1965 over Gifu and Fukui Prefectures of Japan

“…(6) This case may fall under "intense rainfall remotely affected by TY" or "predecessor rain event of TY." However, the difference between this case and cases studied in previous articles (Wang et al 2009; Yoshida and Itoh 2012) indicated significant variety among "intense rainfall remotely affected by TY." Detailed studies for various cases are required to clarify the influence of the distantly located TY on the intense rainfall over Japan.…”

“…Nagai and Fukatu (1967) studied the rainband by using the surface and radar observation data. Wang et al (2009) discussed the role of TY Songe on distantly located heavy rainfall in Japan on September 2̶4, 2004. When the TY was located southeast of Okinawa, a heavy rainfall of~250 mm occurred over south-central Japan on September 2̶4.…”

Multiscale Upstream and In Situ Precursors to the Elevated Mixed Layer and High-Impact Weather over the Midwest United States

“…4a. The poleward transport of water vapor from TC Haima and poleward elongation of enhanced integrated water vapor toward the equatorward entrance region of an intensifying upper-tropospheric jet streak is consistent with the dynamics outlined for a possible predecessor rain event (PRE; e.g., Cote 2007;Wang et al 2009;Galarneau et al 2010;Byun and Lee 2012) over eastern China, South Korea, and Japan. Further analysis of the possible PRE is beyond the scope of the current investigation.…”

The Key Role of Diabatic Outflow in Amplifying the Midlatitude Flow: A Representative Case Study of Weather Systems Surrounding Western North Pacific Extratropical Transition

“…Lately, attention has been paid to the enhanced poleward moisture transport that occurs often on the eastern side of a transitioning TC. When this moisture impinges on a midlatitude baroclinic zone in a region of upperlevel forcing for ascent [e.g., near the equatorward entrance region of an upper-level jet streak; Uccellini and Johnson (1979)] several days prior to ET, heavy precipitation and flooding may occur as a result of quasistationary convection in that region (e.g., Wang et al 2009;Galarneau et al 2010;Byun and Lee 2012;Schumacher and Galarneau 2012;Baek et al 2013). The associated weather system, called a predecessor rain event (PRE; e.g., Galarneau et al 2010;Bosart et al 2012;Moore et al 2013), tends to be located 500-2000 km away from the TC.…”