2012 Atlantic Hurricane Season Birdseye Discussion #29
...JUNE 16 2012...3:05 PM EDT...
Last chance for a June tropical cyclone in the Atlantic beginning June 20. Interests in the Bay of Campeche and western Gulf of Mexico region should monitor this situation carefully. See paragraph P11 below for further details.
...ATMOSPHERIC FEATURES BIRDSEYE CHART...
This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1200Z, and the 1327Z-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...Frontal cyclone from SW Canada and it supporting upper trough have continued east into the Hudson Bay region since the previous discussion. Warm air advection ahead of this frontal cyclone generated a new shortwave upper ridge over the W Great Lakes that has since undergone a tremendous growth across the eastern US...in part due to latent heat release from the central US severe t-storm clouds this frontal cyclone was producing in the previous discussion. This was just the first of a few surface cyclones/shortwave upper troughs that will swing in from SW Canada thru this week...in fact a second is already entering the arena from the upper-left of the above charts and producing another round of central US severe t-storms. Numerical models show a third and even a fourth system swinging in thru June 20.
P2...Upper ridge over the eastern US (mentioned in paragraph P1 above) continues its sprawl...and shows no signs of decaying with ample warm air advection/severe t-storm latent heat release to be expected ahead of all surface cyclones mentioned in paragraph P1. It has absorbed the W Atlantic upper ridge (in paragraph P3 of the previous discussion)...and its eastern convergence has taken over support of all strong surface ridges mentioned in paragraph P3 of the previous discussion. This strong surface ridge currently has a 1034 mb center on the E coast of Canada and 1028 mb center on the NE US coast.
P3...Shortwave upper trough has moved from the SE US into the W Atlantic and Gulf of Mexico...becoming pushed southeastward by sprawling upper ridge in paragraph P2 above. 1014 mb AL/GA border low supported by divergence ahead of this upper trough has moved southwestward into the NE Gulf of Mexico (as a surface trough) while steered by strong surface ridge mentioned in paragraph P2 above...and expect it to continue W across the N Gulf of Mexico while steered by this surface ridge. Yesterday afternoon...this surface trough had a t-storm blow up and was briefly mentioned in the NHC Tropical Weather Outlook...but to no avail as the surface trough was under immense westerly vertical shear S of the upper trough. Surface trough again having a t-storm blow up this afternoon...this time while beneath lower shear directly under the upper trough axis (and perhaps triggered by instability from the cold temps of upper trough axis). I am cautious to sugggest tropical cyclone formation from this surface trough as it is directly below the upper trough. If the t-storm latent heat release shows signs of locally punching out the upper trough...then I will write a special update for possible tropical development (otherwise I don't think it will develop). Finally...1010 mb frontal low SE of Virginia also supported by divergence ahead of this upper trough...and has moved SE toward Bermuda (and now is 1009 mb) while steered in NW flow between surface ridge in paragraph P2 above and dissipating surface low mentioned in paragraph P5 below.
P4...Upper trough over E Canada and 1010 mb surface low it is supporting have moved offshore into the Atlantic high seas in Greenland's vicinity. Surface low has weakened to 1018 mb and is over the S tip of Greenland.
P5...Upper vortex in NW Atlantic persists...but the surface low below is not. The surface low has either dissipated or become absorbed by tail end of cold front mentioned in paragraph P7 below.
P6...Upper-levels of deep-layered anticyclone S of the Azores has dissipated...becoming replaced by the upper trough mentioned in paragraph P7 below. What is left is a surface 1027 mb ridge center at this hour...midway between the Azores and Canary Islands.
P7...Upper trough persists in the NE Atlantic...supported by cold air advection behind the strong surface cyclone it manifested with divergence ahead of itself. This surface extratropical (non-tropical) cyclone has moved into the British Isles per latest satellite imagery. Cold front tailing from this surface cyclone has pushed southward into the Azores...where a new 1018 mb frontal depression has formed thanks to upper divergence ahead of the upper trough.
...TROPICAL BELT DISCUSSION...
P8...Eastern Pacific Hurricane Carlotta and its associated warm core upper anticyclone made landfall in SE Mexico last night...now weakened to a tropical depression due to the landfall. Its warm core upper anticyclone has merged with Panama upper anticyclone to create a singular upper ridge that covers the W half of the Caribbean. Surface tropical wave that was getting sheared on the north side of this upper ridge has been absorbed by the surface low pressure field of Carlotta. Various cloud cover and t-storm activity induced by the outflow of this upper ridge exists across the Bay of Campeche...SE Mexico...W Caribbean...and Central America.
P9...NE Caribbean upper trough from previous discussion persists.
P10...Upper vortex in E tropical Atlantic is breaking up into smaller vortices retrograding westward. In the far east Atlantic towards the W coast of Africa...an upper ridge is redeveloping...an effect due to relatively higher pressures south of the NE Atlantic upper trough mentioned in paragraph P7 above.
P11...Tropical wave approaching the Lesser Antilles in the previous discussion has now crossed the islands into the eastern Caribbean. While crossing the islands...it had produced enhanced weather while interacting with divergence ahead of upper trough in paragraph P9 above...but now is inactive while suppressed beneath this upper trough. Ahead of this tropical wave...t-storms have flared up in the Colombia-Panama area...triggered by split upper flow (between easterlies SE of the W Caribbean upper ridge of paragraph P8...and westerlies SW of the paragraph P9 upper trough). Tonight into tomorrow...this tropical wave will move into this split upper flow and t-storms...and it will be interesting to see if a tropical disturbance gets going as the tropical wave's surface convergence further enhances the agitated weather. If so...I will be upgrading this to a special feature as it appears this is what the computer models have been developing into a Bay of Campeche tropical cyclone around June 20. Challenges this system faces along the way will be land interaction with Central America/SE Mexico and westerly vertical shear by the Gulf of Mexico upper trough (paragraph P3 above). However...models suggest that the disturbance's latent heat release will feed the W Caribbean upper ridge such that the upper ridge's outflow sustains the disturbance...and moreover the upper ridge pushes out the shearing Gulf of Mexico upper trough. What is disconcerting is that models do merge the W Caribbean upper ridge with the east US upper ridge (in paragraph P2 above). If this happened....the upper anticyclonic outflow would be tremendous...which would support a strong tropical cyclone out of this. The eventual fourth frontal cyclone in paragraph P1 above would pull this tropical cyclone northward from the Bay of Campeche...but it is unclear if the cyclone will make landfall on the E Texas coast...or instead turn westward into the S Texas coast or NE Mexico by a ridge that builds behind this fourth cyclone.
P12...Tropical wave S of the Cape Verde Islands in the previous discussion is now WSW of the islands...and remains suppressed beneath the upper vorticity mentioned in paragraph P10.