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Hurricane ANDRES Forecast Discussion Number 12
2015-05-31 04:52:45| National Hurricane Center (East Pacific)
Issued at 800 PM PDT SAT MAY 30 2015 000 WTPZ41 KNHC 310252 TCDEP1 HURRICANE ANDRES DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012015 800 PM PDT SAT MAY 30 2015 Andres has strengthened further today despite moderate northwesterly shear. The cyclone had been maintaining a symmetric central dense overcast (CDO), and the eye had slowly warmed until about 0000 UTC. Over the past few hours though, the CDO has become more irregularly shaped and the eye more indistinct. Dvorak T-numbers were 5.5/102 kt at 0000 UTC from both agencies, and UW-CIMSS ADT values leveled off at 5.7/107 kt. These data suggest that Andres may have been a major hurricane at that time, but satellite data suggest that the cyclone has since begun to weaken. The initial intensity is set at 95 kt, slightly lower than 0000 UTC intensity estimates. Andres is still moving generally northwestward in response to a weakness in the subtropical ridge around 120w. Most of the track guidance shows a high pressure ridge north of the cyclone strengthening on Sunday which should cause the cyclone to turn west-northwestward. Beyond 48 hours, the track models significantly diverge, with the GFS-based guidance depicting a stronger cyclone being steered northwestward over cool waters, followed by an eastward turn. The ECMWF shows a weaker version of Andres eventually turning westward, with its solution on the southern side of the guidance envelope. The official NHC forecast is close to the multi- model consensus (TVCE) through 36 hours. After that, the overly strong GFS run is disregarded, resulting in a track forecast relatively far left of TVCE. The shear over Andres is forecast to decrease dramatically within 24 hours, but the cyclone will be moving over gradually cooler waters and ingesting drier and more stable air during the next couple of days. This competition between dynamic and thermodynamic factors should result in a slow weakening through 48 hours. After that time, even more unfavorable thermodynamic conditions could result in a quicker rate of weakening, and Andres is expected to become a remnant low by day 5. The NHC intensity forecast is close to LGEM and somewhat lower than the multi-model consensus ICON. FORECAST POSITIONS AND MAX WINDS INIT 31/0300Z 15.1N 116.8W 95 KT 110 MPH 12H 31/1200Z 15.6N 117.8W 95 KT 110 MPH 24H 01/0000Z 16.1N 119.1W 85 KT 100 MPH 36H 01/1200Z 16.5N 120.4W 75 KT 85 MPH 48H 02/0000Z 17.0N 122.0W 65 KT 75 MPH 72H 03/0000Z 18.4N 125.1W 50 KT 60 MPH 96H 04/0000Z 19.3N 128.2W 35 KT 40 MPH 120H 05/0000Z 19.3N 130.1W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Kimberlain
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