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 588 
 WTPA43 PHFO 312049
 TCDCP3
  
 Hurricane Miriam Discussion Number  23
 NWS Central Pacific Hurricane Center Honolulu HI   EP152018
 1100 AM HST Fri Aug 31 2018
  
 Miriam has been resilient under increasing vertical wind shear. A
 ragged, cloud-filled eye has reappeared, despite southwesterly
 vertical wind shear of about 25 to 35 kt according to SHIPS and
 CIMSS, respectively. Subjective Dvorak current intensity estimates
 came in at 5.0/90 kt across the board from HFO, SAB, and JTWC, while
 CIMSS ADT yielded 80 kt. Given the longer term improvement in the
 satellite presentation but noting the periodic filling of the eye
 during the past several hours, the initial intensity has been raised
 to 85 kt, which may be conservative.
 
 The initial motion estimate is slightly east of due north (010 
 degrees) at 9 kt. An SSMIS pass from 1352Z suggested some tilt
 toward the northeast with height, which led to the placement of the
 center near the southwestern edge of the eye as seen on
 geostationary satellite imagery. Through the next 24 hours, Miriam
 will continue to be steered northward by a mid to upper level trough
 to the northwest and a deep ridge to the northeast. Later Saturday,
 Miriam will begin a turn toward the northwest. This will occur as
 the steering flow of the weakening system becomes increasingly
 influenced by the low level ridge that will shift to the north of
 Miriam. A general northwestward motion is expected to persist until
 dissipation. The track was nudged to the right of the prior forecast
 and lies near the middle of the guidance envelope, close to HCCA and
 TVCE.
 
 The slight increase in intensity will be short-lived. The already
 vigorous, southwesterly vertical wind shear will increase through
 the next 36 to 48 hours. In addition, SSTs, which are currently
 running around 26.5 C, will steadily decrease along the forecast
 track. Expect weakening to commence later today, with a sharp
 decrease in intensity tonight through Sunday. The intensity
 forecast goes nearly down the middle of the guidance envelope and is
 close to the statistical models and FSSE. On this forecast, Miriam
 will be a tropical storm by Saturday and will weaken to a remnant
 low late Sunday or Monday.
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  31/2100Z 19.2N 141.1W   85 KT 100 MPH
  12H  01/0600Z 20.6N 141.2W   75 KT  85 MPH
  24H  01/1800Z 22.6N 141.7W   55 KT  65 MPH
  36H  02/0600Z 24.6N 143.0W   40 KT  45 MPH
  48H  02/1800Z 26.6N 144.7W   35 KT  40 MPH
  72H  03/1800Z 30.0N 148.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
  96H  04/1800Z...DISSIPATED
  
 $$
 Forecaster Wroe
  
 
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