Tropical Depression Ida may not recover

As mentioned in this morning’s post, Tropical Depression Ida is really taking a beating due to its time over land and the mountainous regions to the west disrupting the storm.

This severe disruption leads to tremendous uncertainty in the NHC’s official forecast. It is unclear if Ida will even be a true tropical cyclone when it enters the northwestern Caribbean. Even if so, how bad will the low-level structure be?

I think of Hurricane Isidore which ran parallel to the northern Yucatan coast before getting pulled into land. At landfall, Isidore was a category three with 110kts (127mph or 204kph) – a beautiful storm aesthetically.

After 36 hours over land, Isidore re-entered the Gulf of Mexico with 50kts (58mph or 93kph). Isidore barely strengthened – 55kts (63mph or 102kph) – before making landfall in Louisiana approximately 48 hours later.

These storms take a huge beating in this region. Inflow is disrupted. Available energy doesn’t reach the center of circulation. Even the best vertically-stacked systems lose their interior structure and have a difficult time recovering.

It’s very difficult to get a hurricane to develop. It’s extremely difficult for one to develop twice.

The NHC expects Ida to survive, but even they raise caution:

IT NOW APPEARS THAT THE CENTER OF IDA WILL REMAIN EAST OF THE HIGHEST TERRAIN IN NICARAGUA AND HONDURAS BEFORE IT EMERGES OVER THE NORTHWEST CARIBBEAN SEA IN ABOUT 24 HOURS. IF IDA SURVIVES UNTIL THEN IT WILL HAVE AN OPPORTUNITY TO RESTRENGTHEN.

Tropical Depression Ida Discussion #8

I wouldn’t officially rule out survival. If I had to put some money on it, though, I’d say it’s highly unlikely Ida will make it to the United States Gulf coast as a tropical cyclone.

Tropical Storm Ida Details

• as of the 10:00 AM EST intermediate advisory:
  • Ida was located about 60miles (111km) south of the Honduras Caribbean coastline or just on the north side of the Honduras/Nicaragua border;
  • moving north (360°) near 6kts (7mph or 11kph);
  • pressure is 1007mb (29.74in);
  • winds are 30kts (35mph or 56kph);

Tropical Storm Ida Forecast Path

• Ida is forecast by the National Hurricane Center (as of 06/1500Z – 9:00 AM CST) to move back over water late tonight or very early Saturday morning, UTC;
• winds are expected to drop as low as 30kts (35mph or 56kph);
• as the storm enters the Caribbean, it is expected to strengthen to a moderate tropical storm with winds of 45kts (52mph or 83kph);
• Ida is expected to come close to the northeast coast of Yucatan Peninsula before making a northeastward turn;

Current watches and warnings

• None as of 10:00 AM EST

Current Weather Conditions

• There are no surface observations coming in from Honduras or Nicaragua within significant distance to the COC;
• Buoy 42057, located about 175 miles northeast of the Honduras/Nicaraguan coastal border, is reporting:
  • east winds (80°) at 14kts (16mph or 26kph) with gusts to 18kts (21mph or 33kph);
  • pressure is 1011mb (29.85in) with a slight rise;
  • air temp is 28°C (82°F); dewpoint is 23°C (73°F);

Sea Surface Conditions

• Buoy 42057 is reporting:
  • water temperature 29°C (84°F);
  • waves are at 4.7 second intervals averaging 4.6ft;
• SSTs in Ida’s forecast track are up to 31°C (88°F) just off the coast of Honduras and northeast Yucatan to 30°C (86°F) along most of the path through the Caribbean;
• OHC values are as high as 120 kJ cm-2 along the east of the forecast track until the northeast Yucatan coast where the center would pass directly;

Satellite Presentation

• a Cloudsat pass 1:15 AM CST shows the northeastern feeder band which contains the deepest convection is as high as 9 miles; reflectivity values are low indicative of low rainfall rates;
• the corresponding GOES IR color image for the above point (same time) shows that same area had cloud tops as cool as -60°C (-76°F); however, the latest IR image (7:45 AM CST) shows deeper convection has built in those feeder bands as cold as the low -70°C (-94°F)s;
• GOES visible imagery (7:45 AM CST) shows those building bands topped with cirrocumulus in the feeder bands with low-level stratocumulus in the southeastern quadrant more indicative of drier, more stable air;

Mid-Atmospheric Conditions

• mid-level shear is limited to the east of Ida with southwesterly winds of up to 20kts (23mph or 37kph);
• wind shear is light to the immediate north of Ida; however, strong westerlies persist from the northern Yucatan across Cuba due to a medium-layer trough across the south and a deep layer trough off the US Atlantic coast;
• Ida appears pretty stacked in the lower levels (850mb to 700mb); however, the 500mb vorticity is further north which extends to 200mb;

Upper-Atmospheric Conditions

• upper-level wind shear over Ida is around 10kts (12mph or 19kph) to the east and up to 25kts (29mph or 46kph) to the north of Ida;
• upper-level divergence is high to the north of Ida over the northwestern Caribbean;

Rainfall

• eTrap 24-hour rainfall forecast totals call for an additional 1 to 2 inches of rain along the northern Caribbean coast of Honduras;
• based on current satellite trends, it is unlikely locations in the southern quadrant of Tropical Depression Ida will see any additional rainfall; if so, it will be very little;

Computer Forecast Models

• the 06/0000Z EMCWF run develops Ida slightly in the western Caribbean, taking the storm a bit east of the NHC’s forecast before turning it northeastward to the north of Cuba and into south Florida late next week;
• the 06/000Z CMC run takes Ida west of the NHC’s forecast deeper into the Yucatan; instead of turning eastward, the CMC takes Ida due north into the south-central Louisiana Gulf coast as a strong tropical storm; wind shear is forecast to be light and the CMC seemingly wants to keep Ida beneath an upper-level anticyclone for much of the forecast;
• the 06/0000Z GFS run follows the same path of the NHC throughout five days. Interestingly, shortly after that period, the GFS stalls Ida and turns it west beneath a high pressure ridge but weakens it due to high upper-level wind shear which the GFS anticipates hampering development for much of the forecast period;
• the 06/0600Z GFDL anticipates Ida quickly becoming a hurricane over the rich western Caribbean waters following the NHC’s path through 96 hours; afterwards, like the GFS, the GFDL turns Ida northeastward similar to the NHC’s forecast, but stalls the system towards the end of the five-day forecast period; at that time, the GFDL believes Ida will be a minimal hurricane to the south of a high pressure ridge;
• the 06/0600Z HWRF is not as aggressive as the GFDL and keeps Ida off the Yucatan Peninsula; however, the model brings Ida back to hurricane status at the time and, again, stalls it in the north-central Gulf of Mexico;
• the 06/0000Z UKMET takes a weak Ida off western Cuba, abruptly turning the system east (either that or it shows a low off western Cuba while Ida is still off the map, then loses the first low) and then north to south of the Louisiana coast and then east-northeastward towards the Florida panhandle; the UKMET does not strengthen Ida;
• the majority of other track models take a similar north-northwestward track towards the Yucatan Peninsula and further north before turning it northeastward; the medium-layer models seem to go with the NHC’s forecast which seems appropriate if Ida does not strengthen much due to structural damage;
• intensity guidance is extremely varied from a weak tropical storm for the next five days to GFDI and HWFI building it to a hurricane, as mentioned earlier;

Conclusion

It should be noted only two hurricanes since the early 1800’s have ever made landfall west of Mississippi – climatologically speaking, it is very difficult to send a hurricane into Texas or Louisiana at this time of the year due to the frequent troughs passing through at lower latitudes.

Looking long-range, even if Ida were to make it to the north-central Gulf of Mexico, waters and the air are cooler so Ida wouldn’t be able to maintain significant intensity.

I’d prefer to simply wait and see how Ida emerges into the northwestern Caribbean before trying to anticipate any US landfall. The only thing for certain at this time is a Yucatan interaction. Whether it makes landfall or not will remain to be seen. That will depend on whether Ida can develop deeper into the atmosphere.

There are very many questions – bottom line. Those from Florida to Louisiana should pay attention. But, I wouldn’t expect Ida to be a mid-season monster of a hurricane.

Related posts:

1. Tropical Depression Four Taking Aim at FL Panhandle
2. Tropical Depression Nine to threaten the southeast next week
3. Ketsana kills 300-plus; Parma goes from depression to Typhoon; Melor a weak Tropical Storm
4. Tropical Depression Two Barely Surviving
5. East Pacific wave trying to become Tropical Depression Twenty-E