SEP. 30, 2013…9:45 P.M. EDT…UPDATE:
Recent satellite loop imagery indicates convection is beginning to fire closer to the center of circulation, near 15.0N…80.8W. The current wind shear map indicates the upper level anticyclone mentioned in my earlier forecast has now centered itself very close to that position. The GFS wind shear forecast from 18Z still indicates upper level winds to remain conducive for some development over the next 48 hours.
Dry air is still an issue as it lies in the path of the disturbance. I will have a full update on this system in the a.m.
Good afternoon everyone!
Tropical Depression Eleven was upgraded to Tropical Storm Jerry earlier. As of the 11:00 a.m. AST advisory from the NHC, the following information was available and is contained in the Global Tracks 7 tracking map:
Based on forecast environmental conditions, some slight strengthening of Jerry is possible over the next 48 hours, before weakening begins to occur.
Based on current and forecast steering layers maps, Jerry should continue on a ENE track with no threat to land over the next 48-72 hours.
The offshore storm I have been speaking of has developed, however does not appear as strong as originally depicted in model guidance. Based on analysis of the global models this morning, this system is forecast to remain far enough offshore, and should not present any real problems for the Mid Atlantic states. The low can be seen in the following surface map from the Aviation Digital Data Service (ADDS)
I am going to monitor the area off the Mid Atlantic coast, for possibility of a secondary low.
Tropical Disturbance INVEST 97L remains disorganized this afternoon. More of an evident circulation is noted in satellite loop imagery, however it remains somewhat broad and not well defined. Based on satellite loop imagery, within the last couple of hours, convection has begun to increase, and will be monitored to see if this is temporary, or an organizational trend.
Currently, the system is still undergoing some wind shear of about 15-20 knots, as the upper level anticyclone projected to develop in the past few runs of the GFS wind shear forecast, has become established just south of the center.
The latest run of the GFS wind shear forecast maps indicate upper level winds may become more conducive for development during the next 18-24 hours, as this upper feature is forecast to shift northward, and over 97L, thereby dropping wind shear values into the favorable range.
Right now, the main inhibiting factor is the presence of dry air to the immediate NW of the system, which is entering the disturbance. However, should convection continue to increase, there is always that chance 97L could overcome this dry air, given the release of latent heat and moisture. This may occur, as the disturbance lies within, and is heading for an area of abundant TCHP (Tropical Cyclone Heat Potential). Based on this analysis, any further development will be slow to occur, save it does not succumb to dry air.
Based on the ATCF FTP information available, the disturbance has been moving generally in a NW direction, however satellite loop imagery, and Latitude and Longitude information over the past 12-18 hour indicate a very slow north of west motion may be temporarily occurring as the disturbance remains in a weak steering pattern. Based on a combination of this, and forecast steering layers maps, I prefer a forecast path at this time in between the southern most dynamic model tracks, and the first track north of those. This is just a preliminary determination on my part, as model guidance is scarce, and is probably due to the disorganized nature of the system. As a note, the global models have lost interest in development of this system.
I will continue to monitor this disturbance for any significant changes over the next 48 hours.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST
MEMBER WEST CENTRAL FL AMS
CERTIFIED SKYWARN OFFICIAL STORM SPOTTER (advanced)