je.st
news
Tropical Storm RACHEL Forecast Discussion Number 8
2014-09-26 10:40:24| National Hurricane Center (East Pacific)
Issued at 200 AM PDT FRI SEP 26 2014 000 WTPZ43 KNHC 260840 TCDEP3 TROPICAL STORM RACHEL DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL EP182014 200 AM PDT FRI SEP 26 2014 Microwave data indicate that Rachel's structure has changed little during the past few hours, and the maximum winds are therefore held at 45 kt. Deep convection remains limited to the southwest of the low-level center, although a recent expansion of the cold cloud tops in infrared satellite imagery suggests that the northeasterly shear may be relaxing just a bit. The SHIPS guidance indicates that the shear should gradually diminish, reaching a minimum in about 36 hours, so gradual strengthening is anticipated up through that time. After 36 hours, the shear is expected to increase while Rachel moves over marginally cooler water and into a drier, more stable environment. Steady weakening is expected to begin by 48 hours, with the cyclone likely becoming a remnant low by day 5. The updated NHC intensity forecast is not too dissimilar from the previous one. However, it should be noted that the 60-kt forecast peak intensity is a little higher than all of the guidance except the HWRF. Rachel's initial motion is 300/12 kt. The track models are in good agreement during the first 36-48 hours, showing Rachel slowing down and turning north-northwestward toward a break in the subtropical ridge. There is significant divergence in the guidance after 48 hours, however. The notable outliers are the GFS and the GFDL ensemble mean, which have a stronger cyclone being pulled northeastward toward the Baja California peninsula by a deep-layer trough over the southwestern United States. The other models show a weaker cyclone stalling and then turning southward or southwestward within the prevailing low-level flow. Due to the model divergence, very slow motion is indicated between days 3-5, and Rachel is expected to become nearly stationary before drifting southwestward during its remnant low stage. The guidance shifted a bit to the west on this cycle, and although the NHC forecast was also nudged in that direction, it still lies on the eastern edge of the envelope. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 18.0N 112.9W 45 KT 50 MPH 12H 26/1800Z 18.7N 114.3W 50 KT 60 MPH 24H 27/0600Z 19.7N 115.4W 55 KT 65 MPH 36H 27/1800Z 20.6N 116.2W 60 KT 70 MPH 48H 28/0600Z 21.4N 116.7W 55 KT 65 MPH 72H 29/0600Z 22.7N 116.8W 45 KT 50 MPH 96H 30/0600Z 23.0N 116.5W 35 KT 40 MPH 120H 01/0600Z 22.5N 117.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg
Tags: number
discussion
storm
tropical
Category:Transportation and Logistics
Latest from this category |
All news |
||||||||||||||||||
|
|||||||||||||||||||