ATL: MELISSA - Post-Tropical - Discussion

[CrazyC83]

Not sure if Subtropical Storm is the best classification; it looks pretty tropical to me. Also I wonder if the winds are conservative?

[HurrMark]

Keep in mind that subtropical storms do not contribute to ACE, so even if this hangs out a while and intensifies, it will add zero ACE as long as it is not fully tropical.

[euro6208]

Second time this name was used for a tropical cyclone in the atlantic and third globally...interesting...

[Hammy]

Not sure if Subtropical Storm is the best classification; it looks pretty tropical to me.

Given the satellite appearance and extremely large wind field it seems to best fit in the subtropical category.

[supercane4867]

Melissa & Ex-tropical storm

[cycloneye]

18z Best Track for Melissa continues as Subtropical at 50kts.

AL, 14, 2013111818, , BEST, 0, 295N, 540W, 50, 987, SS

[hurricanes1234]

Does it look as good as this morning?

[hurricanes1234]

Is that 50 mph or 50 knots? NHC has it as a 50 mph storm.

[cycloneye]

Is that 50 mph or 50 knots? NHC has it as a 50 mph storm.

50 knots.

[hurricanes1234]

I think 50 mph was a little conservative. Here are some images:

10:15 UTC


15:15 UTC


18:45 UTC


Can this strengthen some more? Or will it stop here like Humberto (Part 2 only)?

[Hammy]

Can this strengthen some more? Or will it stop here like Humberto (Part 2 only)?

Humberto was never terribly organized to start with (during part 2) and was headed into 40+ kt wind shear and cooler water more stable air.
Melissa seems to have much more moisture and instability as well as better organization, larger wind field (this isn't going to spin down anytime soon) and far more favorable upper conditions. I'm going to go with strengthening, at least for the next 24 hours.

[hurricanes1234]

Although the cloudtops are warming, Melissa appears to have some good banding. I still think it's far from being fully tropical, but the more time it is subtropical, the better. After all, this type of storm only occurs once or twice on average in the Atlantic per year, and where subtropical cyclones tend to form are well into the unfavourable North Atlantic wind shear, which might sometimes kill non-tropical invests in their early stages. Melissa is very fortunate to be in this region, as outside of its favourable shell lies wind shear in excess of 40 knots, as well as strong subsidence. Nice late-season storm. Intensity has been raised, as of 5 PM, to 50 knots (~60 mph).

[TropicalAnalystwx13]

Because this system is being fueled by atmospheric instability rather than warm ocean temperatures, we should see it intensify mainly during the overnight hours when the temperature difference between the ocean and mid-level of the atmosphere is at its greatest.

Think Chris '12.

[hurricanes1234]

Because this system is being fueled by atmospheric instability rather than warm ocean temperatures, we should see it intensify mainly during the overnight hours when the temperature difference between the ocean and mid-level of the atmosphere is at its greatest.

Think Chris '12.

Yes! I was thinking that too. Especially how Chris strengthened over 23°C waters. Notice that Melissa is only a subtropical storm, yet its pressure is just 7 mbar higher than the most intense Atlantic system of 2013 - Humberto at 980 mbar. I'm thinking diurnal maximum will help Melissa as well with the convection.

[hurricanes1234]

Nice-looking system. Reminds me of Jerry earlier this year, even though Jerry wasn't subtropical.

[cycloneye]

Still Subtropical at 00z.

AL, 14, 2013111900, , BEST, 0, 299N, 546W, 50, 987, SS

[hurricanes1234]

Actually, they lowered the pressure to 985 mbar. Interesting...

AL, 14, 2013111900, , BEST, 0, 299N, 546W, 50, 985, SS

[Hammy]

Actually, they lowered the pressure to 985 mbar. Interesting...

AL, 14, 2013111900, , BEST, 0, 299N, 546W, 50, 985, SS

possibly a ship report or buoy

[hurricanes1234]

You know what else is unique about Melissa? It is a mid-level to fairly strong storm (60 mph) and with an anomalously low pressure of 985 mbar, yet the coldest cloudtops in the system are likely -40°C or warmer. So strange! This is why I like subtropical storms, they are odd little (big) storms!

[cycloneye]

SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...30.3N 54.7W
ABOUT 610 MI...985 KM E OF BERMUDA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...985 MB...29.09 INCHES