2012 Atlantic Hurricane Season Birdseye Discussion #27
...JUNE 14 2012...1:30 AM EDT...
Deep-layered low in NW Atlantic not expected to become subtropical. While Caribbean Sea activity remains on the upswing...the eastern Pacific side of the activity is more favored. See paragraphs P4...P9...and P10 for further details on these situations.
...ATMOSPHERIC FEATURES BIRDSEYE CHART...
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z, and the 1922Z-released HPC analysis.
In light blue is upper air anlaysis, 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 indicating surface lows, Hs indicating 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).
P1...Next frontal cyclone in the mid-latitudes is entering from the upper-left corner of the above charts...from SW Canada.
P2...A low-amplitude shortwave upper trough has also centered entered the arena...currently marked over the central US in the above charts.
P3...Surface frontal cyclone over Canada's Hudson Bay has exited the scope of above charts while moving northward beneath its parent upper trough. A long frontal boundary is left behind by this cyclone...which features a 1006 mb low in E Canada and 1009 mb low offshore of Virginia. Convergence behind this parent upper trough supports a 1018 mb ridge on the Louisiana Gulf coast and 1026 mb ridge over Michigan. Warm air advection ahead of this weather system supports upper ridge which has recently moved offshore into the W Atlantic. Convergence E of this upper ridge axis supports a surface 1030 mb center over S Greenland...and 1020 mb offshore of Newfoundland.
P4...Upper vortex in NW Atlantic persists...and remains stacked above 1010 mb frontal low which is now 1009 mb in the above charts. Accelerational divergence SE of this upper vortex had supported a bare surface front across the central Atlantic over the last 48 hours...but now what is left of this front is a surface trough over the Bahamas and another surface trough about to get absorbed by front attached to 1009 mb low. The Bahamas surface trough almost appears to be merged with the N end of Caribbean Sea tropical wave (mentioned in paragraph P9 below). The Bahamas surface trough has also obtained some t-storm activity with the help of upper outflow from the upper ridge axis mentioned towards the end of paragraph P3 above. With this upper ridge expected to become squeezed out between upper trough in paragraph P3 and upper vortex mentioned in this paragraph...the Bahamas surface trough will lose this favorable environment. The 1009 mb frontal low below the upper vortex continues firing convective cloudiness...perhaps as the upper vortex is cold enough to de-stabilize the atmosphere despite waters of 23 deg C. However...this convective activity has not been strong enough nor close enough to the 1009 mb center for subtropical cyclone development...and the thermodynamic picture is not going to get any better for development (with the cold temp of upper vortex at its pinnacle and sea surface temps not getting any warmer along the 1009 mb center's track). After this assessment...I believe this system has no chance to become a subtropical cyclone.
P5...Deep-layered anticyclone S of the Azores persists...with the surface center now weaker at 1026 mb.
P6...New upper trough has developed in the NE Atlantic...in relatively low pressures between upper anticyclone in paragraph P5 above and upper ridge axis mentioned towards the end of paragraph P3. Satellite animation reveals a sizeable cloud mass and spin heading toward western Europe...which I beleive is a new surface low supported by divergence ahead of this NE Atlantic upper trough.
...TROPICAL BELT DISCUSSION...
P7...Upper trough persists across the Gulf of Mexico tonight.
P8...East-west upper trough has dissipiated in the Caribbean Sea. Upper vorticity midway between the Lesser Antilles and Azores persists.
P9...Upper anticyclone over Cuba has been absorbed by upper ridge axis mentioned toward the end of paragraph P3. 48 hours ago...upper anticyclone toward Panama started enhancing t-storms over the surface ITCZ (discussion #25 paragraph P7). Looking at Hovmoller Diagrams on the NHC webpage...a chunk of this t-storm activity pushed into the eastern Pacific...strengthened beneath high divergence on the SW edge of the Panama upper anticyclone...and now we have tropical depression 3-E in the eastern Pacific tonight. To the east of TD 3-E...tropical wave continues marching west across the Caribbean while enhancing t-storm activity beneath the Panama upper anticyclone and over Central America. Panama upper anticyclone has grown in size while inflated by latent heat release of the tropical wave and TD 3-E t-storms....and in turn the upper anticyclone is aiding the outflow to sustain TD 3-E and the tropical wave.
P10...Considering the computer models over the last days have wanted to develop a west Caribbean tropical cyclone for the latter part of June...it makes sense to be paying strong attention to TD 3-E...tropical wave...and Panama upper anticyclone. TD 3-E seems to have added clarity on how all this will play out...but also has changed things up a bit. Based on the latest discussion and forecasts from the NHC on 3-E...and based on the latest computer model runs...it seems the Panama upper anticyclone is deep-layered enough to steer TD 3-E slowly NW into the S coast of Mexico. I forecast that the highest level of the upper anticyclone will shift west while becoming increasingly associated with strengthening 3-E's latent heat release...and this could be a particularly dangerous situation for the S coast of Mexico if the 200 mb layer of the anticyclone aligns directly over 3-E...which would support healthy upper outflow and rapid strengthening of 3-E. As the upper anticyclone shifts west...this will support unfavorable shearing northwesterlies (and a wake upper trough in the central Caribbean as we are beginning to see)...all of which would prevent tropical cyclone activity in the Caribbean. After 3-E and expansive upper anticyclone make landfall in SE Mexico...there are some model runs suggesting the upper anticyclone would support another tropical cyclone on the Atlantic side of things from June 20 to 23 (starting in the Bay of Campeche tracking across the Gulf of Mexico). Considering typical model performance a week out...taking this scenario superficially at this time...but will definetly be on the lookout as we get closer to June 20.
P11...Upper ridge in E tropical Atlantic has dissipated as the upper-levels of anticyclone in paragraph P5 gains strength from warm air advection ahead of deep-layered 1009 mb cyclone discussed in paragraph P4. As the anticyclone in paragraph P5 continues to gain strength to the north...the E tropical Atlantic is actually reversing into upper vorticity based on latest 200 mb wind barbs in the above atmospheric features chart. Meanwhile...upper ridging has developed to the S of the 1009 mb deep-layered cyclone (where upper-level pressures are relatively higher)...located across the E Caribbean and central tropical Atlantic.
P12...Tropical wave WSW of the Cape Verde Islands 24 hrs ago is approaching the Lesser Antilles tonight...but is under a hostile westerly shear enivronment on the north side of the upper ridge mentioned at the end of paragraph P11 above.
P13...A tropical wave has been added to the NHC TAFB analyses (and likewise toward the lower-right corner above charts) while emerging from western Africa. Since the E tropical Atlnatic is reversing to upper vorticity (as explained in paragraph P11 above)...upper winds will be unfavorable for this tropical wave to develop.