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 846 
 WTPA43 PHFO 300252
 TCDCP3
  
 Hurricane Miriam Discussion Number  16
 NWS Central Pacific Hurricane Center Honolulu HI   EP152018
 500 PM HST Wed Aug 29 2018
  
 While cloud tops associated with Miriam were on general warming 
 trend since the previous advisory, a new burst of convection has 
 recently developed over the center, while organized convective
 bands continue to wrap in to the center from the southeast.
 Subjective Dvorak intensity estimates of 4.0/65 kt from SAB/HFO are
 supported by UW-CIMSS ADT, and that will be the initial intensity
 estimate for this advisory. 
 
 The initial motion estimate is a somewhat uncertain 280/7 kt, as
 the low-level center has been difficult to identify. Miriam has
 moved into an area of light steering flow between a mid-level ridge 
 centered over the southwestern U.S., and a mid- to upper-level low 
 centered northeast of Hawaii. The gradient between the low and the 
 ridge will result in a southerly steering flow that will take
 Miriam toward the north the next couple of days. A turn toward the 
 northwest is expected to begin tonight, followed by a turn toward 
 the north on Thursday, with the dynamical models in good agreement 
 on this evolution. Increasing model spread persists after day 3, 
 with ECMWF taking a deeper cyclone much faster and farther
 northward than the most of the guidance, with this solution taking
 consensus members well to the right of the updated forecast track.
 The official forecast continues to lean toward the GFS and its
 ensemble solution, with Miriam turning west-northwestward toward the
 end of the forecast period as a weak and shallow system primarily
 steered by the low-level trade wind flow. 
 
 The forecast anticipates that Miriam will be in an environment 
 conducive for modest strengthening for the next 24 hours or so,
 with shear near 10 kt and SSTs near 28C. The forecast track toward
 the north will take Miriam over cooler waters thereafter, with SSTs 
 below 26C by 72 h. Southwesterly shear is expected to increase to 
 near 30 kt in 48 h and to 40 kt in 72 h, and Miriam is expected to 
 degenerate into a remnant low by day 4. The official intensity 
 forecast follows trends presented by the multi-model consensus and 
 SHIPS.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  30/0300Z 14.4N 140.6W   65 KT  75 MPH
  12H  30/1200Z 14.8N 141.2W   70 KT  80 MPH
  24H  31/0000Z 16.0N 141.6W   75 KT  85 MPH
  36H  31/1200Z 17.7N 141.5W   65 KT  75 MPH
  48H  01/0000Z 19.4N 141.6W   55 KT  65 MPH
  72H  02/0000Z 22.0N 143.2W   40 KT  45 MPH
  96H  03/0000Z 25.0N 147.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 120H  04/0000Z 27.0N 151.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
  
 $$
 Forecaster Birchard
  
 
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