2014 Atlantic Hurricane Season Birdseye Discussion #78

By: NCHurricane2009 , 6:14 AM GMT on August 30, 2014

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...SATURDAY AUGUST 30 2014 2:15 AM EDT...
Hurricane Cristobal has transitioned into a severe non-tropical gale moving northeastward across the north Atlantic.

Tropical wave Invest 97-L has become a little better organized while moving into the central Caribbean waters southwest of Jamaica. This system has been re-introduced onto the Naval Reseach Laboratory (NRL) site of the US Navy as Invest 99-L...and is at risk of additional development while moving across the western Caribbean...Yucatan Peninsula...and Bay of Campeche. See special feature section below for additional details.

Surface troughing in the Gulf of Mexico...marked as a red dashed line in the atmoshperhic features chart below...has moved northward into the US Gulf coast while steered between the 1023 mb ridge over eastern North America and 1008 mb frontal cyclone moving across the central US. Although this system developed a little further with an increase in showers and thunderstorms supported by the low shear and outflow of a Gulf of Mexico upper ridge (marked by blue zig zag line)...additional development of this system is no longer possible as it interacts with land.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Aug_29_2014_2245Z_zpsbb9a41ed.png
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and the 1930Z-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.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Aug_29_2014_2245Z_Thermo_zps454e7cc1.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).

...SPECIAL FEATURE...TROPICAL WAVE INVEST 99-L (FORMERLY INVEST 97-L)...
Current Prognosis...Tropical wave Invest 99-L is located along 80W longitude this past afternoon and into this evening...becoming a little better organized while the associated showers and thunderstorms is becoming concentrated southwest of Jamaica and northeast of Central America. Satellite animation suggests the vorticity maximum of this tropical wave is along 15N latitude. My updated forecast below is adjusted a bit southward as the location of the vorticity maximum suggests this system is consolidating at a location more southward than I previously expected.

Atmospheric Outlook for the Forecast Period...This system is arriving into a favorable low shear environment to the west of an upper vortex (marked by blue L to the north of 99-L in the above atmo chart) and on the south side of the Gulf upper ridging (marked by blue-zig-zag line). Because this system will be south of the Gulf upper ridge axis during the forecast period...if it does develop it will show limited upper outflow on its north side but plenty of equatorward outflow. Track is expected to be west to west-northwest on the southwest side of subtropical low-level ridging thru the forecast period...with the system not expected to curve north while missing the ridge weakenesses associated with the current central US upper trough/1008 mb frontal cyclone and the next upper trough/surface frontal cyclone (not yet in the atmospheric features chart) to follow behind the 1008 mb frontal cyclone.

Thermodynamic Outlook for the Forecast Period...As the thermodynamics chart above shows...this system will be embedded in a very favorable thermodynamic environment thru the forecast period while tracking over 30 to 31 deg C waters and thru a moist airmass.

24 Hr Forecast (0000Z August 31)...Tropical wave axis in the western Caribbean near 85W longitude producing an organizing storm cluster southwest of the Cayman Islands

48 Hr Forecast (0000Z September 1)...Tropical wave axis producing an organizing tropical low over the southern Yucatan Peninslula near 18N-89W.

72 Hr Forecast (0000Z September 2)...Organized tropical low over the eastern Bay of Campeche centered near 19N-93.5W

96 Hr Forecast (0000Z September 3)...45 mph max sustained wind tropical storm centered near 20N-97W making landfall in east-central Mexico

120 Hr Forecast (0000Z September 4)...Remnant low over east-central Mexico centered near 21.5N-98.5W

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