TROPICAL STORM FORMATION: GRACE, 92L
ALL forecasts contained on this site, are based on my analysis and knowledge of various forecast tools, including information contained in NHC products, and are not copies from any other entity.
*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!
Tropical Storm GRACE was downgraded to depression status earlier today. As of the 5:00 p.m. advisory, the following was available on GRACE:
5:00 PM AST Tue Sep 8
Location: 14.4°N 44.2°W
Moving: W at 18 mph
Min pressure: 1007 mb / 29.74 in
Max sustained: 35 mph
Satellite loop imagery indicates another flare up of convection almost over the center of the depression. However, given the presence of WSW shear and dry air, this may be GRACE’s last breath. Given the current and forecast hostile conditions, I really can’t see her becoming upgraded to a storm again. Wind shear is not forecast to abate, and on the forecast track, GRACE will be under the influence of an upper trof axis. Based on these conditions, I concur with the NHC intensity forecast, and GRACE should dissipate as forecast, if not sooner.
GRACE WIND SHEAR FROM CIMSS
GRACE continues to move slightly north of due west, around the southern periphery of the subtropical ridge, which is rather large at the moment. Based on analysis of the current forecast steering layers maps, the remnants should move more toward the WNW after or beginning near day 5. This may bring whatever could remain, over the island of Hispaniola. Based on analysis of the forecast steering, I concur with the NHC track, and is in very close agreement with the 18Z Dynamic Model guidance TVCN/TVCC track guidance.
I will continue to monitor GRACE until fully dissipated.
Elsewhere, INVEST 92L was designated late yesterday afternoon, and is located to the east of Bermuda. The following information was available on INVEST 92L in the 18Z ATCF FTP product:
Location: 31.4°N 61.7°W
Min pressure: 1013 mb/29.91 in
Max sustained: 30 mph
This INVEST is pretty much stationary at the moment, and I expect this to remain stationary during the next 12-18 hours. Thereafter, based on analysis of forecast steering layers maps, this INVEST should begin to move northward slowly on Wed. and Thurs., and turn toward the NNE, and is shown in the 18Z dynamic guidance. This area is forecast to become absorbed by a large extra-tropical cyclone.
ATCF 18Z DYNAMIC GUIDANCE
Upper level winds are currently non conducive for development, however are forecast to become more favorable within the next 42 hours. The NHC has designated only a MEDIUM (40%) probability of cyclone development during the next 5 days. Preliminary Intensity Guidance does bring it to T.S. strength, however this may be erroneous, and may be possibly being calculated by the modeling as part of the extra-tropical cyclone mentioned in the outlook.
Elsewhere, albeit lying within the 6-8 day forecast range, analysis of global models tends to indicate the modeling continues to hint at a development in the SW to western GOMEX. Bear in mind, yes, model accuracy tends to decrease quicker beyond 72-96 hours, however for the medium range, 6-8 days can be reasonable. For those who have forgotten, during the start of the season, with the first two-three systems, the more reliable global models had nailed them 10-12 days out in the forecast period. With that being said, all of the global models seem to be pretty much in agreement to development, in one form or another, with the ECMWF being the more bullish solution of a tropical storm later in it’s forecast, but initializing the system at 144-168 hours from 12Z today. The GFS indicates a weak low, and is not to excited, with the CMC following with a very small low skirting the coast down in the BOC. The NAVGEM hints at a weak, closed low, while the UKMET is the weakest with an inverted trof (although the forecast for it only goes to 120 hours). Does this mean development will absolutely occur? NO! However, the models are, what we like to term, “sniffing” something out. So as a forecaster, it kinda signals to me we may need to pay attention to the GOMEX down the road.
Based on the current forecast wind shear pattern, I cannot totally rule out development at this time, as within that time frame, the 200 mb streamline pattern is forecast to have an upper level anticyclone begin development in about 6 days, and become established nicely over the Gulf of Mexico.
GFS 200 MB STREAMLINE PATTERN FORECAST
Now, before you go having an anxiety attack, this forecast is just to let you know, I will be monitoring the situation closely, and be looking for persistence, and closer model agreement over the next few days. Thus far, the ECMWF has been consistent in the past 2-3 runs, and it is run only twice a day (albeit it has showed pretty much the same solution in both the 00Z run last night, and the 12Z today). So, I will be looking at all this over the next 5 days fairly close.
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