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2014 Atlantic Hurricane Season Birdseye Discussion #6

By: NCHurricane2009 , 11:27 AM GMT on June 06, 2014

...FRIDAY JUNE 6 2014 7:27 AM EDT...
Tropical disturbance Invest 90-L in the southern Gulf of Mexico has become better organized within the last 24 hours and has the chance to become the first tropical cyclone of the 2014 Atlantic Hurricane Season before unfavorable upper level winds move in on Sunday. This system continues to be mentioned in the 5-day and 48 Hour Atlantic Basin National Hurricane Center Tropical Weather Outlook. Tne only computer model that supports 90-L presently is the CMC which suggests a tropical low moving westward into the east coast Mexico within the next couple of days. See special feature section below for additional details on Invest 90-L...including my updated forecast on this system which predicts tropical cyclone formation within the next 24 hours.

 photo Jun_05_2014_2345Z_zps9427ba1e.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0000Z and 0130Z-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 Jun_05_2014_2345Z_Thermo_zps0e6c678f.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...This system is currently structured as a consolidating 1004 mb surface low in the Bay of Campeche with thunderstorms becoming concentrated just east of the center...which is why it has a shot at becoming a tropical cyclone within the next 24 hours. Upper outflow support for this system comes from upper ridge over the Yucatan and western Central America (blue-zig-zag line located just south of Invest 90-L in the above atmospheric features chart). However the upper ridge remains suppressed to the south of the system as it encounters resistance from northern upper ridge over the US Gulf coast (see blue-zig-zag line in above atmo chart to the north of 90-L). Therefore this disturbance remains in some westerly shear on the north side of the Yucatan/Central America upper ridge...which is why thunderstorms are struggling to build on the west side of disturbance's 1004 mb surface low.

Atmospheric Outlook for the Forecast Period...Shortwave upper trough over the north-central US (blue-dashed line over the eastern Dakotas in above atmo chart) will arrive into the eastern US during next 24 hrs...while another shortwave arrives behind in the western US. US Gulf coast upper ridge will be enforced by low-level warm air advection of surface frontal systems associated with the shortwaves. Strength of Gulf coast upper ridge will keep Yucatan/west Central America upper ridge suppressed just to the south of 90-L...and therefore expect 90-L to remain under westerly shear on the north side of the Yucatan/west Central America upper ridge. Wind shear to increase to hostile levels by 48 Hrs (Sunday) after eastern US shortwave leaves behind a cut-off upper trough dominating the northeastern half of the Gulf of Mexico. 1029 mb Atlantic surface ridge extends all the way to the northern Gulf of Mexico as shown by red zig-zag line in above atmo chart. The weak northern Gulf extension of this surface ridge is expected to slowly push this system westward thru the forecast period.

Thermodynamic Outlook for the Forecast Period...Other than temperatures at 26 deg C minimums in the northeatern Gulf...sea surface temperatures across the Gulf of Mexico are above the threshold for tropical cyclone development...especially where the 1004 mb center of the disturbance is located. Dry air presently not an issue for this disturbance.

24 Hr Forecast (0000Z June 7)...Due to the consolidation of thunderstorms just east of the low pressure center at the present...currently forecast this system to have become a weak tropical cyclone in the Bay of Campeche located at 20N 95.5W by the 24 Hr timeframe. Sheared-off tropical moisture to the east could cause some additional rains over the Yucatan peninsula of SE Mexico.

48 Hr Forecast (0000Z JUne 8)...Forecast weak tropical cyclone to dissipate under hositle westerly shear at a location of 20N 96.5W. Even after dissipation...sheared-off tropical moisture to the south and east could cause some additional rains over the Yucatan peninsula of SE Mexico.

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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