Tropical weather analysis - November 18, 2013

By: KoritheMan , 3:51 AM GMT on November 19, 2013

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Melissa

Subtropical Storm Melissa formed over the central Atlantic today from a non-tropical area of low pressure. As of the latest NHC advisory, the following information was available on Melissa:

Wind: 60 mph, with higher gusts
Location: 30.3°N 54.7°W
Movement: NW at 8 mph
Pressure: 985 mb

The cloud pattern connected to Melissa is still decidedly non-tropical. While the outer convective bands about 100 miles south of the center seen earlier this evening have largely dissipated and convection has formed closer to the center, the cloud tops encompassing this new convection are not particularly cold given the high latitude of Melissa. TAFB furnished a satellite classification of 3.0 as of 0z. While this would normally portend surface winds of only 45 kt, the Dvorak technique only works for systems that are fully tropical, which Melissa is not. A recent AMSU microwave pass shows me that Melissa still lacks an inner core.



Figure 1. Latest infrared satellite image of Subtropical Storm Melissa. Image credit: NOAA's Satellite Services Division (SSD).

While scatterometer fixes have been somewhat patchy, the data I've been able to collect suggests that the radius of maximum winds has contracted compared to 24 hours ago, but Melissa is still embedded within a broader-scale cyclonic low over the central Atlantic, as denoted by surface and satellite observations. AMSU vertical temperature profiles indicate that Melissa is putting up a valiant fight in making the transition to a tropical storm, warming in the upper troposphere has been slow and perhaps unsteady. In addition, water vapor imagery and UW-CIMSS 200 mb vorticity data suggest that Melissa is still well-involved with a large upper-level low pressure system. The SHIPS model analyzed areal sea surface temperatures of only about 25.5C, which appears to be about 1.5C too cold given sea surface temperature maps. Hence, I have high hopes that Melissa will make the transition to a tropical storm on Tuesday, and while, not explicitly shown yet, there is a chance that the cyclone could briefly reach hurricane strength, perhaps up to about 70 kt; this would occur as Melissa moves underneath the axis of a narrow upper ridge forecast to develop over the system in about 24 hours. Subsequently, as the cyclone enters higher latitudes, moves over cold water, and experiences increases in vertical shear, weakening is anticipated. The current model guidance does not show an environment that really screams out "baroclinic forcing" to me, so a steady decline in intensity is expected even after the system becomes extratropical. There is the possibility that Melissa could become a non-convective remnant low at the 48 hour mark before it interacts with an upper-level trough moving off the eastern United States, but the timing and magnitude of this transition is difficult to predict.

Melissa still appears to be moving northwestward, but a turn to the north is expected to manifest very soon as a deep-layer trough moves off the east coast of the United States within the next 12-24 hours. Melissa is expected to move northward only briefly, as the trough will impart mid-level southwesterly flow to the cyclone and accelerate it northeast to east-northeast. The model guidance has no real conundrums except for the end of the period, when the GFS and ECMWF differ significantly on whether Melissa will continue eastward toward western Europe, or whether it will continue north into Greenland. My forecast track compromises the possibilities, lacking any reason to favor one scenario over the other, and is a little left of the current NHC prediction.

Due to the limitations of the track map on which I draw my forecast tracks, I am unable to furnish a forecast point out to day five.

Intensity forecast and positions

INITIAL 11/19 0300Z 30.3°N 54.7°W 50 KT 60 MPH
12 hour 11/19 1200Z 31.5°N 53.8°W 55 KT 65 MPH...TROPICAL
24 hour 11/20 0000Z 34.4°N 51.2°W 60 KT 70 MPH
36 hour 11/20 1200Z 37.1°N 48.2°W 60 KT 70 MPH
48 hour 11/21 0000Z 40.5°N 44.5°W 55 KT 65 MPH
72 hour 11/22 0000Z 45.1°N 40.0°W 50 KT 60 MPH...POST-TROPICAL/EXTRATROPICAL
96 hour 11/23 0000Z 50.7°N 41.0°W 45 KT 50 MPH...POST-TROPICAL/EXTRATROPICAL
120hour 11/24 0000Z 40 KT 45 MPH...POST-TROPICAL/EXTRATROPICAL

Track forecast



Figure 2. My forecast track for Melissa.

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12. WunderAlertBot (Admin)
2:37 AM GMT on November 20, 2013
KoritheMan has created a new entry.
11. Astrometeor
4:33 AM GMT on November 19, 2013
Quoting 8. TropicalAnalystwx13:
You guys are getting nothing. This superstorm will impact Florida, leaving New Orleans hurricane-less, Houston without snow, and Michigan high and dry.


I hope you get rain for Christmas, Cody. AND coal.
Member Since: July 2, 2012 Posts: 101 Comments: 10449
10. wxchaser97
4:28 AM GMT on November 19, 2013
Quoting 8. TropicalAnalystwx13:
You guys are getting nothing. This superstorm will impact Florida, leaving New Orleans hurricane-less, Houston without snow, and Michigan high and dry.


I'm getting exciting weather from this superstorm and that's final.
Member Since: March 16, 2012 Posts: 127 Comments: 7972
9. Astrometeor
4:25 AM GMT on November 19, 2013
Quoting 8. TropicalAnalystwx13:
You guys are getting nothing. This superstorm will impact Florida, leaving New Orleans hurricane-less, Houston without snow, and Michigan high and dry.


No, you can't give the Floridian bloggers here all the satisfaction. That's not spreading the love at all.
Member Since: July 2, 2012 Posts: 101 Comments: 10449
8. TropicalAnalystwx13
4:22 AM GMT on November 19, 2013
You guys are getting nothing. This superstorm will impact Florida, leaving New Orleans hurricane-less, Houston without snow, and Michigan high and dry.
Member Since: July 6, 2010 Posts: 113 Comments: 32706
7. wxchaser97
4:13 AM GMT on November 19, 2013
Quoting 6. KoritheMan:


Snow for Houston on the backside after it smashes into Louisiana. This would occur after the system phases with a trough, like Sandy.

Happy? :)

Whoa whoa whoa, this storm better give SE MI some good impacts before everyone is satisfied.
Member Since: March 16, 2012 Posts: 127 Comments: 7972
6. KoritheMan
4:07 AM GMT on November 19, 2013
Quoting 5. 1900hurricane:

Gotta bring me some snow somewhere in there.


Snow for Houston on the backside after it smashes into Louisiana. This would occur after the system phases with a trough, like Sandy.

Happy? :)
Member Since: March 7, 2007 Posts: 601 Comments: 21230
5. 1900hurricane
4:03 AM GMT on November 19, 2013
Quoting 3. KoritheMan:


You forgot about the part where it turns west into New Orleans after hitting my area.

That way, all the doomcaster crowd gets satiated.

Gotta bring me some snow somewhere in there.
Member Since: August 2, 2006 Posts: 47 Comments: 11694
4. KoritheMan
4:00 AM GMT on November 19, 2013
Quoting 2. GTstormChaserCaleb:
Kori you ever read this one by Bosart and Davis? Link


Nope. Looks interesting though, so I'ma go read it. :D
Member Since: March 7, 2007 Posts: 601 Comments: 21230
3. KoritheMan
4:00 AM GMT on November 19, 2013
Quoting 1. TropicalAnalystwx13:
Naw man, it's gonna phase with that trough to become a Category 6 superstorm that dives into the Caribbean and strikes Jamaica and the Caymans before accelerating into Florida.


You forgot about the part where it turns west into New Orleans after hitting the Miami area.

That way, all the doomcaster crowd gets satiated.
Member Since: March 7, 2007 Posts: 601 Comments: 21230
2. GTstormChaserCaleb
3:56 AM GMT on November 19, 2013
Kori you ever read this one by Bosart and Davis? Link
Member Since: June 30, 2013 Posts: 12 Comments: 8774
1. TropicalAnalystwx13
3:54 AM GMT on November 19, 2013
Naw man, it's gonna phase with that trough to become a Category 6 superstorm that dives into the Caribbean and strikes Jamaica and the Caymans before accelerating into Florida.
Member Since: July 6, 2010 Posts: 113 Comments: 32706

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About KoritheMan

I'm just a 23 year old with an ardent passion for weather. I first became aware of this interest after Tropical Storm Isidore struck my area in 2002.