je.st
news
Tropical Storm Marie Forecast Discussion Number 3
2020-09-29 22:33:58| National Hurricane Center (East Pacific)
Issued at 300 PM MDT Tue Sep 29 2020 000 WTPZ43 KNHC 292033 TCDEP3 Tropical Storm Marie Discussion Number 3 NWS National Hurricane Center Miami FL EP182020 300 PM MDT Tue Sep 29 2020 A WindSat microwave image from earlier this morning indicated that the tropical cyclone's low-level circulation was becoming better defined, with perhaps the formative stage of a cyan ring seen in the 37-GHz channel. Visible images also show the center tucked just beneath recent bursts of deep convection, and Dvorak estimates have risen to T2.0 and T2.5 from TAFB and SAB, respectively. These data, along with ambiguity analyses of recent ASCAT-B and -C scatterometer passes, indicate the depression has strengthened to Tropical Storm Marie with maximum winds of 35 kt. Marie's future track is probably the most straightforward part of the forecast. A mid-tropospheric high anchored over the southwestern United States is steering Marie westward with an initial motion of 275/10 kt. This high will remain the main driver, forcing the cyclone westward or west-northwestward for the next 3 days. By days 4 and 5, Marie is likely to reach a break in the ridge and should slow down a bit and turn toward the northwest. There are no notable outliers among the track guidance, and the small spread among the models yields higher-than-normal confidence in the track forecast. The new NHC forecast is very similar to the previous prediction, and is close to the TVCE and HCCA consensus aids. The intensity forecast is a little more challenging, but mostly because a good proportion of the guidance suggests that Marie will intensify significantly during the next few days. Relatively low deep-layer shear, warm ocean waters, and favorable upper-level divergence all favor strengthening, and several of the various SHIPS Rapid Intensification thresholds are several times higher than their climatological means. In addition, all of the dynamical models, the consensus aids, and the GFS-based SHIPS model bring Marie to hurricane strength within 24 hours. Given these signals, the NHC intensity forecast has been raised from the previous one and lies near or just below the intensity consensus in order to maintain some continuity. But given what is shown by some of the better-performing intensity models, I would not be surprised if subsequent forecasts show a faster rate of intensification or a higher peak intensity. Weakening is expected by days 4 and 5 due to cooler waters and increasing southwesterly shear. Marie's 12-ft sea radii are larger than would be expected for a small, just-developing tropical storm due to a large fetch of southerly swell originating from the Southern Hemisphere. FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 13.6N 109.5W 35 KT 40 MPH 12H 30/0600Z 13.9N 111.6W 45 KT 50 MPH 24H 30/1800Z 14.6N 114.5W 60 KT 70 MPH 36H 01/0600Z 14.9N 117.5W 75 KT 85 MPH 48H 01/1800Z 15.3N 120.3W 90 KT 105 MPH 60H 02/0600Z 16.0N 122.7W 100 KT 115 MPH 72H 02/1800Z 17.2N 124.9W 100 KT 115 MPH 96H 03/1800Z 19.6N 128.5W 85 KT 100 MPH 120H 04/1800Z 21.4N 131.6W 60 KT 70 MPH $$ Forecaster Berg
Tags: number
discussion
marie
storm
Category:Transportation and Logistics
Latest from this category |
All news |
||||||||||||||||||
|
|||||||||||||||||||