TropicalAnalystwx13's WunderBlog

Andrea becomes post-tropical, flooding rains continue; more development in June?

Posted by: TropicalAnalystwx13, 03:13 GMT le 07 juin 2013

Tropical Storm Andrea is no longer with us this evening. After making landfall on the Florida Big Bend yesterday evening with winds of 65 mph, Andrea began to accelerate and quickly lose its tropical characteristics as it felt the effects of the approaching upper-level trough to its west. The low-level circulation remained well-defined up until earlier afternoon, when it began to become elongated and less robust. In addition, surface observations across North Carolina and Virginia earlier this afternoon revealed the cyclone was becoming embedded with a stationary front; accordingly, the National Hurricane Center designated Andrea as a post-tropical cyclone in their 5pm EDT advisory. Typically, this would be the final bulletin on the storm; however, due to the controversy centered around Superstorm Sandy in October of last year, the organization enacted a new policy that allows them to a) continue to advisories on any tropical cyclone that has since transitioned into a post-tropical or extratropical cyclone assuming it poses a significant threat to life and/or property and b) allow tropical cyclone watches and warnings to remain in effect across the affected regions. As of the latest advisory from the National Hurricane Center, Andrea contained maximum sustained winds of 45 mph. The minimum barometric pressure had risen to 997 millibars, and the cyclone was racing towards the northeast at 35 mph. Infrared satellite imagery reveals Andrea has the classic appearance of a post-tropical cyclone, with transient convection north of the center and comma-shaped well removed otherwise.

Thus far, Andrea has produced weather not atypical for a mid-grade tropical storm. Winds along the coast of North Carolina topped out at 53 mph earlier this morning, and widespread 4-5" rainfall totals were observed. Several brief tornadoes, and waterspouts that moved onshore to become tornadoes, were observed as well. The tail-end of the post-tropical cyclone led to torrential rains across the metro area of Miami, where totals in excess of a foot were recorded. Hundreds of cars were stranded, and their residents had to be rescued. One death has been attributed to Andrea so far, linked to a traffic wreck...presumably due to the storm's bad weather across the region...in Virginia.

Figure 1. Infrared satellite imagery of Post-Tropical Cyclone Andrea.

Forecast for Andrea
Andrea has already completed the tropical phase of its life, and it is destined to complete the second phase of its lifespan shortly as well. A majority of the global models indicate that the remnants of Andrea should begin to turn more easterly as they become involved with the upper-level westerlies. After passing southeast of Newfoundland on Sunday, it is likely to be absorbed within a larger extratropical low across the northern Atlantic. In the meantime, however, potentially significant impacts are likely to occur across the Northeast. Several areas have already picked up several inches of rainfall, and a few more may occur before the cyclone moves on tomorrow evening. These rain totals will be capable of leading to isolated road flooding and overflowed river banks, both of which may threaten travel and property. Conditions are no longer favorable for the development of tornadoes, but a strong low-topped storm may be capable of producing a damaging wind gust or two. Localized coastal flooding is possible in conjunction with high tide along the New England shores. Winds of near-gale intensity are expected to impact Atlantic Canada late tomorrow through early Sunday.

Late June development
The 2013 Atlantic hurricane season has already featured one named storm, and now it's time to look down the road for potential development in late June. The CMC continues to indicate the development of a small tropical cyclone just off the eastern coast of Florida in 10 days or so; in fact, both the GFS and ECMWF have now followed suit in showing at least a weak area of low pressure. It should be stated that trough splits often result in small-sized tropical cyclones which are not resolved very well given the aforementioned model's resolutions. In addition to the trough split, the GFS has been very consistent in showing a tropical cyclone...originating from the monsoon trough that is effectively drawn north by the same trough that spawns the cyclone off the Southeast coastline...developing in the western Caribbean only a few days thereafter. Just FYI, the 18z GFS sends a minimal sub-985 millibar hurricane into the coastline of Mexico towards the end of its run. While the track and intensity is not to be worried about at this time, what we should start monitoring is the GFS ensemble mean. A handful of GFS ensembles currently develop this cyclone despite a lack of support from other global models; the GFS is usually best at detecting long range development. Even though the MJO is leaving our region of the world, tropical cyclones can and do form within the downward pulse of the MJO, and the tropics will have to be watched for mischief, especially after June 15.

I'll have a new blog early next week,

TropicalAnalystwx13

Categories:Tropical Cyclones of 2013 Tropical Weather

Updated: 03:44 GMT le 08 juin 2013

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Tropical Storm Andrea moves ashore; Invest 92L and the outlook for the rest of June

Posted by: TropicalAnalystwx13, 03:12 GMT le 07 juin 2013

The 2013 Atlantic hurricane season just started on June 1 but already we have our first named storm, Andrea. The system developed from a broad monsoonal gyre combined with the mid-level remnants of Hurricane Barbara from the eastern Pacific. Initially dubbed Invest 91L, the disturbance tracked slowly northward over the past few days, positioning itself north of the Yucatan Peninsula yesterday. Despite its ragged appearance on satellite imagery early in the morning, ...

Categories:Tropical Weather Tropical Cyclones of 2013

Updated: 15:09 GMT le 07 juin 2013

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Tropical Storm Andrea develops in the Gulf, huge rainfall producer for East Coast

Posted by: TropicalAnalystwx13, 03:50 GMT le 06 juin 2013

The first named storm of what promises to be an exceptionally active and dangerous year, Andrea, has developed in the Gulf of Mexico this evening. The upgrade comes after an Air Force hurricane hunter plane investigation into what was previously dubbed Invest 91L found a well-defined and closed low-level center underneath a deep burst of shower and thunderstorm activity. As of the latest advisory from the National Hurricane Center, Tropical Storm Andrea contains max...

Categories:Tropical Cyclones of 2013 Tropical Weather

Updated: 03:54 GMT le 06 juin 2013

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Unforeseen circumstance: Tropical Storm Alvin weakening, dissipation likely soon

Posted by: TropicalAnalystwx13, 03:05 GMT le 17 mai 2013

Tropical Storm Alvin, the first named storm of the 2013 Pacific hurricane season, developed well south of the coastline of Mexico last night as a result of an area of low pressure that formed several days prior, west of Guatemala. At the time of formation, Alvin was a well-developed tropical cyclone, with fantastic banding and upper-level outflow. The same cannot be said tonight, unfortunately. Strong westerly wind shear on the order of 20 to 25 knots, not foreseen ...

Categories:Tropical Cyclones of 2013 Tropical Weather

Updated: 03:25 GMT le 17 mai 2013

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ALVIN! The first named storm of the 2013 Pacific hurricane season develops on cue

Posted by: TropicalAnalystwx13, 22:13 GMT le 15 mai 2013

Not dissimilar to the 2012 Pacific hurricane season, which featured both Tropical Storm Aletta and Hurricane Bud in May, we are once again starting the hurricane season right on cue. What was once Invest 90E intensified into Tropical Depression One-E early this morning and further to Tropical Storm Alvin as of the latest update. The most recent information from the National Hurricane Center states maximum sustained winds have increased to 40 mph, and the minimum bar...

Categories:Tropical Cyclones of 2013 Tropical Weather

Updated: 22:20 GMT le 15 mai 2013

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