TROPICAL STORM BONNIE FORECAST SYNOPSIS…ISSUED 6:45 P.M. EDT…MAY, 28, 2016

TROPICAL CYCLONE FORMATION: BONNIE
TROPICAL STORM WATCH: NONE
TROPICAL STORM WARNING: IN EFFECT
HURRICANE WATCH: NONE
HURRICANE WARNING: NONE

Disclaimer:  This site is not affiliated with the National Hurricane Center, Storm Prediction Center, or National Weather Service.  ALL forecasts herein are the result of my analysis, and I am solely responsible for the content.
(T. F. “Storm” Walsh III)

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Good evening everyone!

As of 5:00 p.m. EDT, the NHC in Miami has upgraded Tropical Depression TWO, to Tropical Storm BONNIE.  Based on information contained in the 5:00 P.M. advisory from the NHC, the following was available on BONNIE:

5:00 PM EDT Sat May 28
Location: 31.1°N 79.4°W
Moving: NW at 10 mph
Min pressure: 1008 mb / 29.77 in
Max sustained: 40 mph

NHC WEBSITE LINK:
http://www.nhc.noaa.gov/

HURREVAC NHC TRACKING MAP
hurrevac BONNIE

hurrevac BONNIE.WIND

WATCHES AND WARNINGS …
CHANGES WITH THIS ADVISORY: None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for… * Savannah River to Little River Inlet South Carolina.

A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 12 hours.

For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office.

18Z INTENSITY FORECAST GUIDANCE
td2 18Z INTENSITY GUIDANCE

18Z DYNAMIC MODEL TRACK GUIDANCE
td2 18Z DYNAMIC GUIDANCE

Based on the NHC advisory, satellite loop imagery, current and forecast steering layers maps, Bonnie is moving to the NW.  Based on analysis of the current steering layers forecast maps, valid 00Z tonight, and 18Z Dynamic Model guidance, I concur with the NHC forecast track which is ever slightly to the right of the consensus model suite, in that BONNIE should continue a NW motion during the next 18-24 hours.  Based on this, I agree with the NHC landfall scheme, however I believe the center will pass very close and come ashore near Edisto Beach, SC.  Residents within the WARNING area should have preparations close to complete.  The following impacts are of concern in and near the WARNING are.  The following is are local statements issued by the Wilmington NWS office as of 4:55 P.M. EDT, and Charleston NWS as of 5:31 P.M. EDT:

NWS WILMINGTON NC LOCAL STATEMENT LINK:
http://www.nhc.noaa.gov/text/WTUS82-KILM.shtml

NWS CHARLESTON, SC LOCAL STATEMENT LINK:
http://www.nhc.noaa.gov/text/WTUS82-KCHS.shtml

Main concerns will be, but are not limited to HEAVY RAINFALL, FLOODING, MINOR SURGE, RIP CURRENTS, DOWNED TREE BRANCHES, etc.

Satellite loop imagery indicates BONNIE is not that all organized and in fact, you can see where the center of the LLC was detached from the burst of convection in the beginning of the loops.  The last few images indicate the LLC coming under the heavy convection.  This is a good sign she may be trying to become slightly better organized, and the beginning of the slow strengthening mentioned, prior to landfall.  Analysis of the current upper level pattern, while not optimal (lack of an upper level anticyclone), the streamline flow at 200 mb is rather strongly diffluent, which is allowing for some moderate divergence aloft, based on the current wind shear product from CIMSS.  Further analysis shows very minimal convergence at the surface.

NOAA BONNIE FLOATER SATELLITE LOOP IMAGERY
avn0-lalo.bonnie

rgb0-lalo.bonnie

CIMSS WIND SHEAR PRODUCT
tccaptureshearpat

The latest available shear forecast from the NOAA HFIP model site, per the GFS, indicates shear to be around 11 kts, which would closely coincide with the shear product from CIMSS.  The storm is just edging into the eastern wall of the Gulfstream which is running 27-28C at the moment.  Putting all of this together, I concur with the NHC intensity that BONNIE could attain 45 MPH sustained winds, briefly, as wind shear is forecast to increase in the next 24 hours.

NHC INTENSITY FORECAST:

INIT 28/2100Z 31.1N 79.4W 35 KT 40 MPH
12H 29/0600Z 31.9N 80.1W 40 KT 45 MPH
24H 29/1800Z 32.8N 80.5W 35 KT 40 MPH…INLAND
36H 30/0600Z 33.2N 80.1W 30 KT 35 MPH…INLAND
48H 30/1800Z 33.5N 79.4W 30 KT 35 MPH…INLAND
72H 31/1800Z 34.5N 77.8W 25 KT 30 MPH…INLAND
96H 01/1800Z 35.0N 76.5W 25 KT 30 MPH…POST-TROP/REMNT LOW
120H 02/1800Z 35.7N 75.3W 25 KT 30 MPH…POST-TROP/REMNT LOW

Once BONNIE makes landfall, forecast steering indicates a turn to the NE, but with a slow motion.  In fact steering is forecast to collapse, and BONNIE could stall or meander along the coast 24 hours after landfall.  Thereafter, the forecast calls for the remnant to drift E or NE 48 hours into the forecast time frame.

Residents of the warned area should continue to monitor the progress of this storm closely, and follow instructions per the NHC and local NWS Warnings and advisories.

CHARLESTON NC DOPPLER RADAR LOOP (CLICK ON IMAGE)
CLX.N0Q.20160528.2159

NWS HAZARD AND WARNINGS MAP (LINKED)
US

It is my intention to post another update sometime tomorrow afternoon/early evening

Elsewhere, analysis of global models this evening does not indicate any development, with the exception of the CMC GGEM, which indicates a low developing near Cuba at around 138 hours (5-6 days), and becoming a TS moving to the NE.  The ESRL PSD 500 mb Mean Norm. Anomaly forecast and ECMWF 500 mb anomaly maps do indicate lowering of pressures once again in about 72 hours, however I have to discount the GGEM as the outlier, as the other global models do not indicate development, and the wind shear forecast calls for upper level winds to be non conducive over the area.  I will monitor the area for any significant pressure falls during the next 72-96 hours however.

GGEM 138 AND 168 HOUR FORECAST
ggem.138
GGEM.168
ESRL PSD 500 MB MEAN NORM. ANOMALY
z500nanom_f072_usbg

ECMWF 500 MB ANOMALY MAP
ecm_z500_anom_conus_4
Elsewhere, Tropical Storm formation is not expected during the next 5-7 days.
Have a blessed evening!

T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS
CoCoRAHS OBSERVER

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