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Lixion A. Avila and Jamie Rhome

deep-layer ridge to the north, the depression produced occasional bursts of deep convection while moving westward and west-southwestward until it degenerated into a remnant low around 0000 UTC 24 October. The remnant low continued to move generally westward for the next couple of days within the low-level steering flow. It then turned northward before dissipating on 27 October. 3. Forecast verification For all operationally designated tropical (or subtropical) cyclones in the Atlantic and eastern

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Edward N. Rappaport

increased to 20–25 kt on the east side of the low by that day, but a well-defined closed circulation was not evident. A mid- to upper-tropospheric short-wave trough approaching from the southwest enhanced convection near the system center. Operationally, National Weather Service (NWS) analyses and forecasts designated this system as an extratropical cyclone through its lifetime. A poststorm analysis of all data subsequently available suggests, however, that the system had a mostly subtropical

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James L. Franklin, Lixion A. Avila, John L. Beven II, Miles B. Lawrence, Richard J. Pasch, and Stacy R. Stewart

-southwestward. There were occasional bursts of convection for the next day or so, but the depression degenerated into a remnant low on 16 November about 630 n mi southwest of Cabo San Lucas. 4. Forecast verifications For all operationally designated tropical cyclones in the eastern North Pacific basin, the NHC issues an “official” forecast of the cyclone's center position and maximum 1-min surface wind speed. These forecasts are issued every 6 h, and each contains projections valid 12, 24, 36, 48, and 72 h after

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John L. Beven II and James L. Franklin

Storm Calvin and dissipated 2 days later. Tropical Depression 9-E was observed from 13–15 August. Finally, Tropical Depression 11-E formed on 23 August from a broad low pressure system that likely resulted from a combination of a tropical wave and a background monsoon environment. Winds were near tropical storm force at genesis. However, no further development occurred, and the system dissipated the next day. 4. Forecast verification The Tropical Prediction Center (TPC) issues advisories every 6 h

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Michael J. Brennan, Richard D. Knabb, Michelle Mainelli, and Todd B. Kimberlain

a frontal zone on 14 October. The resulting extratropical low developed gale-force winds on 16 October until it was absorbed by a larger extratropical low on 17 October north of the Azores. 4. Forecast verification and warnings For all operationally designated tropical (or subtropical) cyclones in the Atlantic and eastern North Pacific basins, NHC issues an “official” forecast of the cyclone’s center location and maximum 1-min surface wind speed. Forecasts are issued every 6 h and contain

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Richard D. Knabb, Lixion A. Avila, John L. Beven, James L. Franklin, Richard J. Pasch, and Stacy R. Stewart

back into the ITCZ on 21 October about 800 n mi southwest of Cabo San Lucas. 3. Forecast verifications For all operationally designated tropical cyclones in its area of responsibility, the NHC issues an “official” tropical cyclone track (latitude and longitude of the circulation center) and intensity (maximum 1-min wind speed at 10 m above the surface) forecast every 6 h. These forecasts are made for the 12-, 24-, 36-, 48-, 72-, 96-, and 120-h periods from the initial synoptic time of the forecast

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James L. Franklin and Daniel P. Brown

-air observations supplement the satellite and reconnaissance data. In key forecast situations, the kinematic and thermodynamic structure of the storm environment is obtained from dropsondes released during operational “synoptic surveillance” flights of NOAA’s Gulfstream IV jet aircraft ( Aberson and Franklin 1999 ). Several satellite-based technologies play an important role in the analysis of tropical weather systems. Foremost of these is multichannel passive microwave imagery [e.g., from the Tropical

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James L. Franklin, Richard J. Pasch, Lixion A. Avila, John L. Beven II, Miles B. Lawrence, Stacy R. Stewart, and Eric S. Blake

, ship and buoy reports, and weather radars. In key forecast situations, the kinematic and thermodynamic structure of the storm environment is obtained from dropsondes released during operational “synoptic surveillance” flights of NOAA’s Gulfstream IV jet aircraft ( Aberson and Franklin 1999 ). Several satellite-based remote sensors play an important role in the analysis of tropical weather systems. Foremost of these is multichannel passive microwave imagery [e.g., from the Tropical Rainfall

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Lixion A. Avila and John L. Guiney

Servicio Meteorologico Nacional de Mexico and USAFR reconnaissance in Hurricanes Lester and Madeline. Figure 2 shows the 1998 eastern North Pacific tropical cyclone tracks. 3. NHC forecast verification The NHC began operational forecasting of eastern North Pacific tropical cyclones in 1988. Every 6 h; the NHC issues its “official” tropical cyclone track and intensity forecast for periods extending to 72 h. The quality of the forecasts is evaluated using the postseason best track database. Track error

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D. M. Rodgers, M. J. Magnano, and J. H. Arns

series of annual summaries assembled as a documentation for those interestedin investigating the mesoscale convective weather systems that occur over the United States.1. Introduction Much attention has been focused in recent yearson mesoscale convective systems (MCSs). Mesoscaleconvective weather presents many challenges to theresearch and operational meteorological communities.These challenges range from gaining understandingof various physical processes and scale interactionsto using new

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