2012 Atlantic Hurricane Season Birdseye Discussion #41
...JULY 3 2012...10:05 AM EDT...
Outside of vigorous tropical wave activity...none of which is organizing at this time...Atlantic tropics remain calm.
...ATMOSPHERIC FEATURES BIRDSEYE CHART...
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 0600Z, and the 0724Z-released HPC analysis.
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...
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).
...MID-LATITUDES DISCUSSION...
P1...Frontal system anchored by 1003 mb center in western Dakotas now has a 1001 mb center in NE Manitoba...and its supporting upper trough follows behind. Warm air advection ahead of this frontal system supports a growing upper ridge over central North America which still has an anticyclonic center over NE New Mexico.
P2...Complex frontal system covering the northwest half of the discussion area (eastern North America and northern Atlantic) persists. A frontal cyclone and its supporting upper trough is making landfall in western Europe (marked as an extratropical low in the upper-right of the above charts). A 1004 mb frontal cyclone and associated supporting upper trough is centered over eastern Canada. Convergent back side of the upper troughing continues to support surface ridging....including a 1016 mb center in the NE Gulf of Mexico...1017 mb center over the SE US...and 1014 mb center over eastern Canada. Finally...Texas cut-off upper trough has dissipated in the face of strengthening upper ridge mentioned in paragraph P1...and this system has delivered yet another cut-off upper trough moving SE across the western Atlantic and Bahamas.
P3...Upper ridge over the Atlantic and south Greenland remains split in three areas by mass cool air advection behind the complex frontal system in paragraph P2 above. The northern part is an upper ridge over Greenland and the high seas south of Greenland. The middle part is an upper anticyclone in the open Atlantic currently SE of the Azores...and looks to become part of the east Atlantic upper ridge in paragraph P11 (and hence is moved to that paragraph of the tropical belt discussion). The southern part is an upper anticyclone still located in the eastern Caribbean...and hence has its own paragraph in the tropical belt discussion (see paragraph P10).
P4...Surface trough from old frontal boundary remains in the upper-right corner of the above charts toward southern Spain and northern Morocco. Cut-off upper vortex south of the Azores persists. Surface trough south of the Azores also persists...today supported by split flow upper divergence between the NE edge of the upper vortex and NW edge of the middle upper anticyclone mentioned in paragraph P3. Finally...cut-off upper trough E of Bermuda persists...but likely will merge with upper troughing of the complex frontal system in paragraph P2. The central Caribbean fragment of this cut-off upper trough remains stationary...and is moved to paragraph P9 of the tropical belt discussion.
P5...Open Atlantic surface ridge still has a strong center....which is now 1029 mb and SW of the Azores as of 0600Z TAFB. Expect it to regain strength as it becomes supported by upper convergence on the back side of the upper trough/surface frontal cyclone currently pushing into Europe (paragraph P2).
...TROPICAL BELT DISCUSSION...
P6...Upper ridge in the western Gulf of Mexico has merged with sprawling central North America upper ridge mentioned in paragraph P1.
P7...Inverted upper trough over the Yucatan and southern Gulf of Mexico has retrograded westward about the upper ridge in paragraph P1 and into the Bay of Campeche.
P8...Small upper ridge over Central America is enhancing upper outflow for t-storm activity across the region.
P9...Central Caribbean upper vorticity persists...originating as a cut-off from the weather system in paragraph P4.
P10...Eastern Caribbean upper anticyclone persists...originating as a cut-off from the decaying upper ridge mentioned in paragraph P3.
P11...Expansive east Atlantic upper ridge continues...and is merging with upper anticyclone SE of the Azores mentioned in paragraph P3. In conjunction with the surface ridge in paragraph P5...deep-layered easterly flow exists across much of the Atlantic tropics that is advecting African desert dry air (brown shading in the above thermo birdseye chart) westward. Three inverted upper troughs on the south side of this east Atlantic upper ridge show up today...but not sure what caused them at this hour.
P12...Tropical wave in the central Caribbean (formerly Invest 97-L) is becoming suppressed by central Caribbean upper vorticity mentioned in paragraph P9.
P13...Vigorous tropical wave midway between the Cape Verdes and Lesser Antilles in the previous discussion is moving closer to the Lesser Antilles. This tropical wave is struggling with the dry air mentioned in paragraph P11. However...it is producing a small area of rapidly moistening air east of the Lesser Antilles while getting help from split flow upper divergence located at the west end of the upper ridge mentioned in paragraph P11. More interesting...long-term satellite animation suggests that this tropical wave left behind a surface low pressure southwest of the Cape Verde Islands...whose signature is well-defined at this hour with a t-storm cluster in that area. Perhaps this surface low will get absorbed by the next tropical wave mentioned in paragraph P14.
P14...The next strong tropical wave has entered the tropical waters of the Atlantic from western Africa. As it continues westward...it may absorb disturbed weather southwest of the Cape Verde Islands (left behind by the tropical wave in paragraph P13). This tropical wave is also in favorable low shear thanks to deep-layered easterly flow mentioned in paragaraph P11...but may not develop if it struggles with the dry air also mentioned in paragraph P11.
Reader Comments
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Last paragraph (P14) shows my lastest thinking on that wave...its still in favorable low shear but is headed toward dry air (source of which is mentioned in paragraph P11)...much like the strong wave that preceeded it (paragraph P13). If it doesn't develop an impressive upper outflow structure to ventilate itself for persistent t-storms...then it will succumb to the dry air and not develop. My bet for now is that it will fail against the dry air...
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