Good afternoon everyone!
I had planned on having this out earlier, however my PC keeps freezing and running slow.
Tropical Storm Chantal has strengthened, albeit you’d never know by satellite imagery. As of the 11;00 a.m. EDT Advisory from the NHC, the following was available on Chantal: 11:00 AM AST Tue Jul 9
Location: 14.4°N 61.5°W
Moving: WNW at 29 mph
Min pressure: 1006 mb
Max sustained: 60 mph
NHC LOCAL STATEMENTS
NHC FORECAST INTENSITY
FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 14.4N 61.5W 50 KT 60 MPH 12H 10/0000Z 15.8N 65.0W 55 KT 65 MPH 24H 10/1200Z 17.4N 68.5W 60 KT 70 MPH 36H 11/0000Z 19.3N 71.5W 35 KT 40 MPH...INLAND 48H 11/1200Z 21.3N 73.6W 35 KT 40 MPH 72H 12/1200Z 24.5N 76.0W 45 KT 50 MPH 96H 13/1200Z 26.5N 77.0W 45 KT 50 MPH 120H 14/1200Z 27.5N 78.0W 40 KT 45 MPH
Chantal continues to move very quickly toward the WNW. I expect this motion to continue for the next 24-36 hours up until she reaches the Island of Hispaniola. After this time, the western periphery should begin weaken as a break in the ridge is forecast by the steering forecast maps. This will allow Chantal to take a track into the Bahamas. As this weakness becomes stronger, steering flow will weaken, and Chantal should slow her forward speed. Soon thereafter, a ridge builds back in to her NE, and a turn more to the Florida Coast should take place. Based on the current steering layers map displaying a weakness over the Bahamas, and the current run of the forecast steering layers maps from the PSU e-WALL site, I concur with the current NHC forecast track up to day 4-5, however based on a blend of CMC and GFS track forecast, I prefer in between the NHC Official track, and the TVCC / TVCN consensus. Based on this, the East Central Florida Coast, to possibly the Georgia border, could come under a Tropical Storm Watch / Warning in a few days.
12Z DYNAMIC MODEL GUIDANCE
Looking at satellite loop imagery, I was rather surprised by Chantal hitting 60 mph. Her signature is fairly ragged, however information passed about radar signature seems to indicate she has a tightly wound core.
Chantal is still battling with wind shear out of the NW at about 15-20 knots. The most recent (I have no idea what is taking the update so long) Zonal Shear forecast map from the GFS does indicate Chantal may fall under the Zero zonal shear value sometime later this afternoon, so some further slow strengthening could occur over the next 24 hours, albeit her fast forward speed could become a hindrance.
Based on the current forecast track, in which most Dynamic Models and Ensembles are pretty much in agreement with, as Chantal feels the weakness in the ridge, she should slow her forward speed over the Bahamas. The NHC indicates a weakening, however, I have to agree with one of my colleagues, meteorologist Bob Acanfrio, that Chantal will need to be monitored closely, as if she hangs around the area long enough and she is slow enough, the zonal shear indicates a substantial weakening in shear values, which could possibly allow her to try and build an upper level anticyclone, albeit brief in nature.
I will continue to monitor Chantal closely, and will try to have an earlier update tonight, provided my PC agrees with me.
Elsewhere, the GFS is still persistent in developing another Tropical Storm in the EATL/CATL in about 4 days from now. Again, the entity that may be the trigger is just off the West African Coast. Albeit none of the other models, especially the ECMWF (The EURO hasn’t even initialized Chantal yet), I will not rule this out right now, as according to the current wind shear forecast, this should have upper air support as it crosses the Atlantic.
Tropical Storm formation is not expected during 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)