2014 Atlantic Hurricane Season Birdseye Discussion #4

By: NCHurricane2009 , 2:32 AM GMT on June 04, 2014

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...TUESDAY JUNE 3 2014 10:32 PM EDT...
Enhanced thunderstorm activity persists in the Gulf of Mexico extending southward to Tropical Storm Boris in the Eastern Pacific. This system has been re-introduced into the 5-day and 48 Hour Atlantic Basin National Hurricane Center Tropical Weather Outlook. The GFS computer model continues to be the most aggressive in suggesting tropical cyclone formation from this system over the course of the next week. This system continues to be a special feature on this blog with the assumption that it will become the first tropical cyclone of the 2014 Atlantic Hurricane Season. See special feature section below for my current genesis forecast.

...ATMOSPHERIC FEATURES BIRDSEYE CHART...
 photo Jun_03_2014_2045Z_zps56112d44.png
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. Ls indicate surface lows, Hs indicate surface highs.

...THERMODYNAMICS BIRDSEYE CHART...
 photo Jun_03_2014_2045Z_Thermo_zps5f231ce9.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...GULF OF MEXICO DISTURBANCE...
Current prognosis...Within the last 24 hours a shortwave upper trough/surface frontal 1001 mb depression... marked in upper-left corner of above atmo chart...has amplified western Mexico upper ridge into Texas (see blue-zig-zag line over Texas in above atmo chart). As a result...the upper vortex formerly part of this disturbance has retrograded westward around the Texas upper ridge and out of the picture into Mexico. This leaves behind the surface trough of the disturbance...with axis of showers and thunderstorms shifting westward in the wake of the upper vortex and becoming more co-located with surface trough. Upper ridge over the eastern part of the disturbance (blue-zig-zag line over eastern Gulf/NW Caribbean in above atmo chart) is also shifting westward in the wake of the upper vortex. Surface convergence provided by the surface trough and outflow of upper ridge continue driving the active weather in the region. It continues to be forecast that by 1800Z June 4 (24 Hrs from now) that the upper ridge will consolidate into an anticyclonic center over the Yucatan Peninsula...with the northern portion of the surface trough diminshing while the southern portion thrives toward the outflow of the anticyclonic center. However...the dissipation of of the northern portion of the surface trough has already occurred...with the southern portion consolidating toward a 1005 mb low over Mexico's Bay of Campeche coast (marked in above atmo chart) and toward the low pressure field of eastern Pacific Tropical Storm Boris.

Atmospheric Outlook for the Forecast Period...The 1020 mb ridge over the western Atlantic continues shifting east and will merge with 1034 mb ridge over the Atlantic (both marked with red Hs in the above atmo chart). As such...surface ridges over the mid-latitude Atlantic and mid-latitude Pacific will flank North America thru the forecast period...with shortwave upper troughs and associated surface frontal systems diving across North America in between the ridges. This pattern will favor a general northward track toward the ridge weaknesses associated with the frontal systems for any tropical cyclone that forms from this system.

Thermodynamic Outlook for the Forecast Period...Other than some minor 26 deg C minimums in the northern Gulf...sea surface temperatures across the Gulf of Mexico are above the threshold for tropical cyclone development. Dry air associated with upper vortex no longer obstructing west side of disturbance now that it has retrograded out of the picture as noted in above current prognosis section. However dry air is expected to again invade from the west in association with a cut-off upper trough forecast to develop beginning in 72 Hrs.

24 Hr Forecast (1800Z June 4)...Favorable upper ridge is forecast to concentrate into an anticyclonic center over the Yucatan Peninsula of SE Mexico. Surface trough in the Gulf should continue to consolidate toward the the anticyclonic center of the upper ridge where upper outflow will be maximal. Surface trough will also be enforced by the northward travel of Tropical Storm Boris or its remnant low pressure field. Showers and storms forecast to concentrate over the southern Gulf...SE Mexico...western Central America..and adjacent East Pacific...while supported by the surface trough and upper ridge.

48 Hr Forecast (1800Z June 5)...Forecast no change from 1800Z June 4 forecast

72 Hr Forecast (1800Z June 6)...Southern extent of eastern US shortwave upper trough no longer shown to be in the Gulf of Mexico in latest GFS computer model run...and therefore wind shear in the Bay of Campeche not forecast to be as high as previously thought. Therefore with favorable dynamics persisting from 1800Z June 4 to 1800Z June 6...their maybe enough time for an organizing surface low over the Bay of Campeche to form by this time.

96 Hr Forecast (1800Z June 7)...Eastern US shortwave forecast to leave behind cut-off upper trough in northeastern Gulf of Mexico...which will increase westerly shear across forecast Bay of Campehce surface low...but not enough to inhibit tropical cyclone formation with the prior thunderstorm latent heat release of this disturbance having enforced the favorable upper ridge which will protect it from some of the shear.

120 Hr Forecast (1800Z June 8)...Same dynamics as June 8 forecast...with forecast Bay of Campeche surface low becoming a tropical cyclone. Due to the westerly shear...this will likely displace the tendency for tropical cyclone formation eastward toward the eastern Bay of Campeche/NW Yucatan Peninsula region.

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