2015 Atlantic Hurricane Season Birdseye Discussion #17

By: NCHurricane2009 , 1:58 AM GMT on June 10, 2015

...TUESDAY JUNE 9 2015 10:00 PM EDT...
The disturbance in the western Caribbean Sea remains active due to surface convergence supplied by a tropical wave moving in from the central Caribbean coupled with upper divergence supplied by a growing upper ridge (marked by blue H in the atmospheric features chart below). Simultaneously the southern part of the upper trough associated with the 998 mb eastern North America frontal cyclone has fractured over the southeastern US and northern Gulf of Mexico (fracture is marked by blue-dashed line). This fracture is expected grow into an upper vortex covering a large area of the Gulf of Mexico as this disturbance reaches the southwestern Gulf in 3 to 4 days. Even though this upper vortex has the potential to diminish after 5 days...it may be expansive enough to interrupt this disturbance's chances for tropical development. The CMC and NAVGEM models which previously showed this disturbance developing in the Gulf of Mexico no longer show development.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...

This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1920Z-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. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...

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 temperature isotherms at http://www.nhc.noaa.gov/satellite.php...the site from which the above thermo chart is generated from...are currently outdated. Therfore I have approximated the 26 deg C isotherm in the above chart using the sea-surface temperature maps available at www.wuwnderground.com/tropical. 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).


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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3:30 AM GMT on June 11, 2015
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