2016 Atlantic Hurricane Season Birdseye Discussion #177

By: NCHurricane2009 , 4:41 AM GMT on November 23, 2016

...TUESDAY NOVEMBER 22 2016 11:41 PM EDT...
Otto strengthens further into a hurricane...and additional strengtheing is expected before Otto makes landfall in southern Nicaragua and Costa Rica later this week. Therefore interests in these areas and offshore southern Caribbean islands should be rushing preparations to completion for a possible severe strike from a strong hurricane. See the special feature section below for additional details on Otto. Visit www.nhc.noaa.gov for up to the minute latest information on Otto...including watches and/or warnings that are currently in effect.


This chart is generated based on surface analysis from the National Hurricane Center TAFB at 1800Z and 1933Z-released WPC analysis.

Areas of Interest maybe first introduced circled by a yellow-dashed line. If the area of interest becomes introduced in the 5-day National Hurricane Center (NHC) Atlantic tropical weather outlook then it gets upgraded with a green-dashed line encircling it. If the area of interest gets upgraded to an Invest or is mentioned in the 48-hour NHC Atlantic tropical weather outlook then it gets upgraded with a green-solid polygon encircling it.

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 (also called an upper vortex or upper cyclone), blue Hs are locations of upper ridges (also called upper anticyclones).

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. Surface troughs labeled with TW indicates the trough is a tropical wave whose origin is from the mid-level African Easterly Jet. Ls indicate surface lows (cyclones), Hs indicate surface highs (ridges/anticyclones).


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).

Current Prognosis...While strengthening into a hurricane this past afternoon...the cloud field of Otto expanded...became more symmetric...and took on a large comma shape...and the wind field expanded accordingly. However this evening...the outer cloudiness appears to have eroded due to some intrusion of dry...cold...stable air being driven southward by the large 994 mb frontal cyclone entering the west Atlantic. Very recently...the inner core has re-organized with a strengthening and rather compact circular thunderstorm mass while the outer cloudiness remains weak...and the wind field has shrunken. This might indicate Otto has recently re-organized into a rather compact hurricane tonight. As of 0000Z earlier this evening the center of Otto was beginning a westward drift while passing over 10.5N-80W.

Atmospheric Outlook for the Forecast Period...Otto has finally begun a westward drift while finally becoming steered by the 1031 mb ridge over eastern North America approaching from the northwest. Meanwhile as the large upper trough/surface frontal cyclone over the west Atlantic shifts eastward and away...upper-level winds have become more favorable as the ventilating upper ridge over Otto now has room to re-locate and expand at a position directly on top of the hurricane...espeically while bolstered by the latent heat release of Otto's thundrestorm activity. The westward drift of Otto is expected to remain slow for the next 48 to 72 hours as the 1001 mb frontal cyclone and its upper trough over the central United States weakens the steering 1031 mb ridge. By 96 hours this frontal cyclone will have moved into the Atlantic which will allow the ridge to re-build north of Otto...resutling in a westward acceleration of Otto into the eastern Pacific.

Thermodynamic Outlook for the Forecast Period...Otto will be over favorable 29 deg C waters in the southern Caribbean supportive of tropical development. It appears the large mass of dry..cool...stable air immediately north of the hurricane may not have an effect on the hurricane as the hurricane has recently established a protective tight core of strong thunderstorms per the above current prognosis section.

My (red) track and intensity forecast points in the above graphic:

24 Hr Forecast (0000Z Nov 24)...85 mph maximum sustained wind hurricane centered offshore of Nicaragua and Costa Rica at 10.5N-81.5W

48 Hr Forecast (0000Z Nov 25)...100 mph maximum sustained wind hurricane centered just offshore of Nicaragua and Costa Rica at 10.5N-82.5W

72 Hr Forecast (0000Z Nov 26)...50 mph maximum sustained tropical storm centered over north-central Costa Rica at 10.5N-84.5W

96 Hr Forecast (0000Z Nov 27)...Remnant low centered over the eastern Pacific at 10.5N-87.5W

Track Forecast...Computer models continue to trend with a weaker version of the 1001 mb frontal cyclone currently crossing over the central US. This will allow the steering ridge to the north of Otto to remain stronger and therefore I have upped the westward pace of my forecast track in the 72 to 96 hour timeframe to begin catching up with the latest model guidance. I may have to continue increase the westward pace of the forecast track in later updates.

Intensity Forecast...With Otto remaining a compact tropical cyclone and a history of compact tropical cyclone rapidly intensifying...with warm waters of 29 deg C (thermodynamic outlook section)...and with favorable upper-level winds (atmospheric outlook section)...I continue to forecast Otto to reach category 2 100 mph maximum sustained wind strength before landfall. I also continue to show rapid weakening and dissipation by 96 hours after landfall as compact storms like Otto can rapidly weaken...even over smaller land masses like Central America. However should the westward pace of the track forecast continue to increase...this would allow Otto to reach eastern Pacific waters more quickly and thus Otto might survive its passage over Central America. In such a scenario the National Hurricane Center would retain the name Otto as it moves into the eastern Pacific...and I would continue to issue special feature sections with forecasts on Otto. However should Otto dissipate and then later re-generate in the eastern Pacific...it would be re-named as an eastern Pacific tropical cyclone and I would not be tracking it on this blog.

Impact Forecast...The impact swath in the above forecast graphic is an extrapolation of the 10 PM EDT NHC tropical storm wind field along my forecast track.

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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