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2014 Atlantic Hurricane Season Birdseye Discussion #60

By: NCHurricane2009 , 4:45 AM GMT on August 11, 2014

...MONDAY AUGUST 11 2014 12:46 AM EDT...
The strong tropical wave previously over interior western Africa has emerged into the eastern tropical Atlantic waters south-southeast of the Cape Verde Islands. The disturbance has been introduced into the National Hurricane Center Tropical Weather Outlook and has been upgraded to Invest 94-L on the Naval Research Laboratory Site of the US Navy. See special feature section below for additional details on this system.

 photo Aug_10_2014_1945Z_zps63707406.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and the 1928Z-released WPC analysis.

Features boxed in green...if any...are mentioned in the National Hurricane Center (NHC) traditional 48-hour outlook and or are considered an "Invest" on the Naval Research Laboratory site of the US Navy at the time the chart was generated. I do not box features in green if they are only included in the NHC's longer term 5-day outlook.

In light blue is upper air analysis, with 200 mb wind barbs calculated by GOES satellite imagery showing the upper-level wind direction. Based on the 200 mb wind barbs, blue-dashed lines are locations of upper troughs, blue-zig-zag lines are locations of upper ridges. Blue Ls are locations of upper lows, blue Hs are locations of upper ridges.

In red is surface analysis, with solid lines indicating locations of surface fronts, dashed lines indicating locations of surface troughs, and zig-zag lines indicating surface ridge axes. Ls indicate surface lows, Hs indicate surface highs.

 photo Aug_10_2014_1945Z_Thermo_zpscd7d0558.png
This chart is generated using GOES water vapor satellite imagery. Brown indicates dry air. White, blue, and purple indicates moist air. An increase in moisture indicates slower air parcel lapse rates with elevation and hence an increase toward instability.

Sea-surface temperatures are overlaid with light blue isotherms. The 26 deg C isotherm is highlighted in red. Waters at and south of the 26 deg C isotherm indicate low-level warmth and hence faster environmental lapse rates with elevation (more instability). Waters north of the 26 deg C isotherm indicate slower environmental lapse rates with elevation (less instability).

Current prognosis...As of 1800Z the NHC TAFB has defined a 1010 mb low pressure spin centered near 11N-22W associated with our strong tropical wave that has recently emerged from western Africa. Their is a large amount of surrounding showers and thunderstorms loosely organized around this low pressure spin. Therefore my current forecast for this system shown below gives it 72 hours before becoming a tropical cyclone with the assumption that this is a large system that will take some time to consolidate.

Atmospheric Outlook for the Forecast Period...Thru the forecast period this system will be steered west around the south side of the low-level 1026 mb Atlantic subtropical ridge marked in the atmospheric features chart above. As the chart above also shows...upper vorticity marked by blue-dashed lines and blue Ls is located in the central tropical Atlantic...northeastern Atlantic... and northwestern Atlantic. Over the next few days...this upper vorticity is forecast to merge into a Tropical Upper Tropospheric Trough (TUTT) with the tropical wave finding itself in a favorable low shear/good upper outflow environment in a tropical upper ridge to solidfy south of the TUTT. However by the end of the forecast period...the TUTT is forecast to shift south ahead of a building upper ridge in the central Atlantic. It is uncertain whether or not this system will be able to escape the unfavorable TUTT as it shifts south...which is why I develop the system slowly at the end of my forecast shown below.

Thermodynamic Outlook for the Forecast Period...As this system continues west it will encounter the swath of dry Saharan air that has recently killed off the tropical waves out ahead of this system. The current assumption is that the dry air will not be an issue because this tropical wave is stronger and more organized than the recent previous ones...but my forecast below develops this system slowly due to the uncertainty of dry air in addition to the unfavorable TUTT discussed in the atmo outlook section above. As far as sea-surface temperatures...the tropical wave will be tracking over 27 to 28 deg C thru the forecast period which will be on the favorable side for tropical development.

24 Hr Forecast (0000Z August 12)...Tropical low centered near 11N-28W.

48 Hr Forecast (0000Z August 13)...Tropical low centered near 11N-34W.

72 Hr Forecast (0000Z August 14)...35 mph max sustained wind tropical depression centered near 11N-40W.

96 Hr Forecast (0000Z August 15)....45 mph max sustained wind tropical storm centered near 11N-46W.

120 Hr Forecast (0000Z August 16)...50 mph max sustained wind tropical storm centered near 12N-52W.

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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2. WunderAlertBot (Admin)
2:32 AM GMT on August 12, 2014
NCHurricane2009 has created a new entry.
1. KoritheMan
5:02 AM GMT on August 11, 2014
I'm more partial to the tropical wave behind 94L.

But I do believe the real season will begin by the fourth week of August. The models should soon respond to the anticipated pattern change (trough to ridge) over the east coast by showing development in the western Atlantic.
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