Image Department Meteorology
Meteorology_Home Weather_Server News/Seminars
People
Research
Academics Application Contact_Us

Hawaiian_Weather
US_Mainland_Weather
Tropical_Weather
Satellite_Imagery
Radar_Imagery
Marine
Numerical_Models
LAPS
Forecasts
Observations
Archive
Links Disclaimer
Space
SOEST_Home
University_of_Hawaii_Home

 674 
 WTPZ45 KNHC 281456
 TCDEP5
 
 Tropical Storm Miriam Discussion Number  10
 NWS National Hurricane Center Miami FL       EP152018
 800 AM PDT Tue Aug 28 2018
 
 A very recently arriving high-resolution microwave overpass
 indicates that Miriam is a sheared tropical cyclone.  The GPM pass
 shows that the center of Miriam is located well northwest of the
 primary mass of deep convection due to moderate northwesterly
 shear.  The center of the cyclone is located well west of the
 earlier position estimates, which has also required a re-location.
 The most recent Dvorak estimates from TAFB and SAB, as well as
 UW-CIMSS/ADT, support an initial intensity, however, this could be
 generous given the recent microwave data.
 
 Environmental conditions are not expected to change over the next
 24 hours, with possibly a slight reduction in the shear in 24 to 48
 hours.  This would suggest that Miriam should only gradually
 strengthen over the next couple of days and it is likely to reach
 its peak intensity in 2-3 days.  After that time, increasing
 southwesterly shear and cooler waters are expected to initiate
 weakening.  By 96 hours, the shear is forecast to become quite
 strong and Miriam will be moving over sub 26C SSTs. These
 progressively hostile conditions should cause Miriam to become
 a post-tropical cyclone by 120 hours. The latest intensity forecast
 is close to the FSU Superensemble, and generally in between the ICON
 and HCCA consensus models.
 
 The initial motion continues to be due westward, or 270/12 kt,
 as Miriam continues to be steered around the southern periphery of
 a subtropical ridge.  A mid- to upper-level trough northeast of
 Hawaii will weaken the western periphery of the ridge over the next
 couple of days, and Miriam is forecast to turn northwest then
 north-northwest, between the ridge and the aforementioned trough.
 Forecast models diverge regarding the forward speed of Miriam
 at days 3-5, depending how they handle the interaction of Miriam
 with the the trough to its northwest. The ECMWF continues to favor
 an accelerating northward track as Miriam gets caught in strong
 southerly flow on the eastern side of the trough. The GFS is much
 farther southwestward, as it appears to take a more shallow Miriam
 westward later in the forecast period.  Since the consensus
 aids remain clustered between these two scenarios, the latest
 forecast NHC track is once again near the various consensus models.
 
 FORECAST POSITIONS AND MAX WINDS
 
 INIT  28/1500Z 14.2N 135.4W   55 KT  65 MPH
  12H  29/0000Z 14.2N 136.9W   55 KT  65 MPH
  24H  29/1200Z 14.3N 138.9W   60 KT  70 MPH
  36H  30/0000Z 14.7N 140.4W   65 KT  75 MPH
  48H  30/1200Z 15.6N 141.3W   75 KT  85 MPH
  72H  31/1200Z 18.5N 141.8W   75 KT  85 MPH
  96H  01/1200Z 22.0N 142.6W   50 KT  60 MPH
 120H  02/1200Z 26.0N 144.8W   35 KT  40 MPH...POST-TROPICAL
 
 $$
 Forecaster Brown/Latto
 
 
Return to the Tropical Systems Page for MIRIAM

Back to main Tropical Weather page




This page is maintained voluntarily by the MKWC and the UHMET faculty, staff, and students.
It was last modified on: Thu, Jul 23 2020 - 2003 UTC
Send comments to: Ryan Lyman