June 10th, 2013 Category: Clouds VIIRSSuomi-NPP

Tropical Storm Yagi (03W) – June 9th, 2013

While Tropical Storm Yagi (03W) churns to the south of Japan, a large, spiralling area of convection can also be observed to the east of the country. Atmospheric convection is the result of a parcel-environment instability, or temperature difference, layer in the atmosphere. Different lapse rates within dry and moist air lead to instability. Mixing of air during the day which expands the height of the planetary boundary layer leads to increased winds, cumulus cloud development, and decreased surface dew points. Moist convection leads to thunderstorm development, which is often responsible for severe weather throughout the world.

Tags: Area of convection Japan | Comments |

March 7th, 2013 Category: Tropical Storms

Area of Convection – March 6th, 2013

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Track of Area of Convection

An area of convection is located near 17.7S 153.4E, approximately 215nm east- southeast of Willis Island, Australia. Animated multispectral satellite imagery depicts an elongated but consolidating low-level circulation center (LLCC) with flaring deep convection near the LLCC and improved convective banding in the northern and southern peripheries.

An ASCAT pass reveals the overall elongated orientation of the system as it is embedded within the monsoon trough and also shows the strongest winds are located in the peripheries. Upper-level analysis continues to show a developing anticyclone near the center with good poleward and equatorward outflow.

The LLCC is currently located in an area of moderate (10-20 knot) vertical wind shear (VWS) with areas of strong VWS located just to the north and south of the system. Sea surface temperatures are favorable at 28 to 30 degrees celsius. Maximum sustained surface winds are estimated at 25 to 30 knots. Minimum sea level pressure is estimated to be near 996 mb. The potential for the development of a significant tropical cyclone within the next 24 hours is high.

Tags: Area of convection Australia Willis Island | Comments |

February 20th, 2013 Category: Tropical Cyclones

Tropical Cyclone Haruna (16S) – February 19th, 2013

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Track of TC 16S

Tropical Cyclone Haruna (16S) (click here for previous images) is forecast to weaken due to land interaction near TAU 72, then more significant weakening as it tracks over cooler SSTs and encounters increasing vertical wind shear south of Madagascar.

The system is forecast to complete ETT by TAU 120. Overall, the dynamic model guidance is in fair agreement and supports the JTWC forecast track; however, there is low confidence in the JTWC forecast due to the weak steering enviroment and uncertainties in track speed after TAU 72. The system is now expected to intensify to a peak of 75 knots by TAU 36 due to favorable conditions. Maximum significant wave height is 20 feet.

Tags: 16S Area of convection Haruna Madagascar Tropical Cyclone | Comments |

February 19th, 2013 Category: Tropical Cyclones

Tropical Cyclone Haruna (16S) – February 19th, 2013

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Track of TC 16S

The area of convection near Madagascar (click here for previous images) has now strengthened into Tropical Cyclone Haruna (16S). The system is located approximately 385 nm west-southwest of Antananarivo, Madagascar, and has tracked westward at 04 knots over the past six hours.

Animated infrared satellite imagery indicates rapid consolidation over the past twelve hours with tightly-curved deep convective banding wrapping into a well- defined center. An SSMI 37 ghz image depicts a microwave eye feature and supports the initial position with high confidence. Based on the SSMI image and previous microwave imagery, the system motion has become quasi-stationary and appears to be looping.

Upper- level conditions remain very favorable with weak vertical wind shear, radial outflow and warm SST. Over the past twelve hours, the subtropical steering ridge (STR) has weakened due to an approaching shortwave trough and TC 16S is currently tracking slowly and erratically within a weak steering environment.

Dynamic model guidance supports slow track motion through TAU 48 until a deep shortwave trough deepens south of Madagascar. Thereafter, the system will accelerate southeastward while undergoing extra-tropical transition (ETT).

Tags: 16S Antananarivo Area of convection Haruna Madagascar Tropical Cyclone | Comments |