TROPICAL STORM FORMATION: GRACE
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*NOTE: In the TROPICAL STORM FORMATION line above, probabilities are for during the next 5 day period. My personal probability will be listed as either NONE, MONITORING or PROBABLE. This does not necessarily mean something will develop, but that certain forecast conditions are likely to be present, favoring development. Once NHC products become available, then the appropriate probability and percentage will be used.
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Current Storm Total for 2015:
TOTAL STORMS: 7
INTENSE HURRICANES: 1
U.S. LANDFALLS: 2
StormW’s Seasonal Forecast:
TOTAL STORMS: 8
INTENSE HURRICANES: 1
Good day everyone!
Enter Tropical Storm GRACE.
Tropical Storm GRACE is located in the far eastern Atlantic, and is the seventh storm of the season. As of the 5:00 p.m. EDT advisory from the NHC, the following information was available on GRACE:
Analysis of satellite loop imagery indicates GRACE was better organized earlier this evening, and does not appear as well structured at the moment. I attribute this to GRACE being affected by an upper level trof, currently located to her NW, in very close proximity, and the effect of somewhat drier air entering her northern portion (based on close up water vapor imagery). Shear values are within conducive limits, however one will note, that she has moved out from under the upper level anticyclone that had been over her prior to now. This has cause the upper level outflow to be less than optimal.
This should arrest any strengthening or further organization at the moment. Based on the current wind shear forecast which is in line with the NHC forecast discussion, there should be an improvement in the upper level pattern, with the development of the upper level anticyclone once again over or very close to GRACE. Based on this, but with the presence of the slightly drier air, organization may be slower to occur. Recent OHC data indicates GRACE will be moving through some higher OCH during the next couple of days, and this may help temporarily in the mixing out of slight dry air intrusion. In a few days however, as mentioned in the NHC forecast discussion, the low to mid levels of the atmosphere are expected to become drier. This would definitely put a hamper on any further strengthening. Based on the premise that the upper level environment is currently forecast to improve, and the presence of higher OHC to the west, I concur with the NHC intensity forecast at the moment, in that the storm should begin weakening as it encounters increasing SWLY shear, and pretty much matches the more accurate of the intensity models in the 18Z guidance.
NHC INTENSITY FORECAST
FORECAST POSITIONS AND MAX WINDS
INIT 05/2100Z 12.6N 26.4W 35 KT 40 MPH
12H 06/0600Z 12.9N 28.3W 40 KT 45 MPH
24H 06/1800Z 13.2N 30.8W 45 KT 50 MPH
36H 07/0600Z 13.5N 33.6W 50 KT 60 MPH
48H 07/1800Z 13.9N 36.4W 45 KT 50 MPH
72H 08/1800Z 14.8N 42.3W 45 KT 50 MPH
96H 09/1800Z 15.1N 48.4W 40 KT 45 MPH
120H 10/1800Z 15.7N 53.8W 35 KT 40 MPH
ATLANTIC OHC MAP
Based on analysis of the current forecast steering layers maps, valid for 00Z this evening, the subtropical ridge is forecast to fluctuate slightly during the next 96-120 hours, but pretty much maintains it’s southern periphery strong enough to keep GRACE on a W to WNW motion. Based on this, and the probability of GRACE weakening per the forecast, I agree right now with the NHC westward motion near the end of the 5 day forecast period. Should she strengthen more steadily than forecast prior to this, I would prefer the TVCN track in the 00Z Dynamic Guidance.
I will continue to monitor GRACE for any significant changes.
Elsewhere, Tropical Storm formation is not expected during the next 5-7 days.
Have a blessed day!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /
SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS