WTPZ42 KNHC 250233

Tropical Storm Greg Discussion Number 31
NWS National Hurricane Center Miami FL EP072017
800 PM PDT Mon Jul 24 2017

The cloud pattern of Greg has changed little during the last several hours. The low-level center of the storm remains covered up by an area of deep convection that has increased in intensity during the past few hours. The latest Dvorak classifications are largely unchanged from earlier, and the initial wind speed estimate remains 40 kt for this advisory. This intensity estimate is also in fairly close agreement with the earlier scatterometer data.

Greg has made the expected turn to the west-northwest on the south side of a low- to mid-level ridge. The models suggest that Greg should move west-northwestward to northwestward during the next couple of days as the ridge to the north of the system weakens a little. A turn to the west and then west-southwest is expected in 2 to 3 days when Greg becomes a shallow system and is steered by the low-level trade wind flow. The NHC track forecast is a tad to the north of the previous one, trending toward the latest model consensus aids.

The tropical storm is still over relatively warm 27 deg C waters and in a low wind shear environment. The environment along the projected path of Greg is expected to become hostile during the next couple of days, with the cyclone forecast to move into a progressively drier air mass and over waters cooler than 26 deg C beginning in about 24 h. In addition, a significant increase in northwesterly wind shear is expected to begin in 36 to 48 h. These unfavorable conditions should cause a steady weakening trend, and Greg is forecast to become a remnant low by 72 h. The NHC intensity forecast is identical to the previous one and in line with the bulk of the model guidance.


INIT 25/0300Z 14.8N 134.9W 40 KT 45 MPH 12H 25/1200Z 15.4N 135.9W 35 KT 40 MPH 24H 26/0000Z 16.3N 137.3W 35 KT 40 MPH 36H 26/1200Z 17.1N 138.7W 35 KT 40 MPH 48H 27/0000Z 17.5N 140.2W 30 KT 35 MPH 72H 28/0000Z 17.0N 143.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 29/0000Z 16.0N 146.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 30/0000Z 15.0N 148.5W 20 KT 25 MPH...POST-TROP/REMNT LOW

$$ Forecaster Cangialosi