Shear killing Rick; dry air beating Lupit; Caribbean disturbance not interesting – yet

Even the most powerful of hurricanes and typhoons are no match to the simple element of wind and dry air.

Tropical Storm Rick is a shadow of its former self, somewhat surprisingly, but it should have been anticipated.  Rick will never be a hurricane again and residents in Baja California Sur and Sinaloa are breathing easy.  However, rainfall continues to be a serious threat.

Meanwhile, dry air has entered Typhoon Lupit and caused considerable weakening though Lupit is still a category two typhoon.  More interesting is that Lupit has continued a west-northwest track which is now opening the idea of missing the Philippines.

Could two areas already hit hard by major cyclones this year catch a huge break like this?

In addition, I’ll have an update on the Caribbean tropical wave as well as the new area of interest in the central Atlantic.

Tropical Storm Rick

Quick Hits:

• current winds 55kts (63mph or 102kph), pressure 991mb (29.26in), moving north-northeast at 5kts (6mph or 9kph);
• tropical storm warnings in effect from Agua Blanca, Baja California Sur on the Pacific coast south and around to Buena Vista on the Gulf of California coast, tropical storm watches from El Roblito on the mainland north to Altata and on the Baja California peninsula from Buena Vista to La Paz;
• Tropical Storm Rick has tropical storm-force winds 220 miles wide southeast to northwest;
• A 19/2326 UTC TRMM overpass catching the northern quadrant of Rick estimates pockets of rainfall rates just under an inch at most;
• wind shear over Rick at the moment is west-southwesterly 15kts (17mph or 28kph) to 20kts (23mph or 37kph);
• thus, wind shear is blowing heaviest convection into the eastern quadrant of Rick and limiting development.  Cloud tops in a small area as low as -70°C (-94°F) are elongated southwest to northeast from just north of the center of circulation;
• 24-hour rainfall totals are forecast to be as much as four to eight inches.  However, as Rick moves inland mainland Mexico these rates will be higher due to mountain-causing updrafts;
• 20/0900 UTC NHC forecast calls for Rick to pass roughly 75 miles south of Cabo San Lucas, Baja California Sur and come inland 50 miles or so north of Mazatlan, Sinaloa;
• Additional weakening of Rick is likely prior to landfall though the NHC anticipates Rick packing winds near 50kts (58mph or 93kph).

The demise of Tropical Storm Rick is obviously welcome news.  However, there is still considerable threat of flash-flooding and mudslides beginning today as heavy rains from Rick come ashore.  As mentioned, mountains cause uprising so as the wind and moisture blow into the mountains and are forced up, it causes rapid condensation and additional rainfall.  Current rainfall rates estimated in Rick of under 1in/hour could rise considerably as the heaviest convection moves ashore late tonight or tomorrow morning.

Typhoon Lupit

Quick Hits:

• Typhoon Lupit is a category two typhoon with sustained winds of 95kts (109mph or 176kph), pressure of 952mb (28.11in), moving west-northwest at 8kts (9mph or 15kph);
• Typhoon Lupit has tropical storm-force winds 305 miles at it’s widest from southeast to northwest;
• dry air is embedded in the cyclone and visible on water vapor and infrared imagery to the south of the eye – this has aided in weakening Lupit from yesterday’s super typhoon status;
• current wind shear values over Lupit is light, 10kts (12mph or 19kph) at most.  Lupit is on the western edge of an upper-level anticyclone;
• Typhoon Lupit is forecast to make landfall late Thursday or early Friday, UTC, along the northern coast of Luzon, Philippines as a minimal category two typhoon with winds of 95kts (109mph or 176kph);
• The steering subtropical ridge to the north of Lupit should push the cyclone on a west-southwestward track soon; some models are forecasting a recurving cyclone prior to landfall, however lack of a break in the ridge makes such a forecast unlikely, according to the JTWC;
• the subtropical ridge should also enhance outflow in addition to an area of divergence Lupit will be moving into within about 24 hours.

What makes this forecast very interesting now, in my opinion, is how much longer Lupit continues to moving west-northwest or even west.  It doesn’t take a genius to see that another 24 hours on the current forward heading and the Philippines should be spared a direct landfall.

I emphasize “should”.

It is also possible the ridge could be a bit stronger to the north of the Philippines which could push Lupit even more west-southwesterly than forecast.

Consistency is the key with the computer models.  They have shown it by anticipating a very similar path to the official forecast though they have been wrong thus far in turning Lupit more southerly.

I think the next 24 hours are very critical and we should know this time tomorrow if the Philippines will take a direct hit or, hopefully, a near miss.  Typhoon-force winds only extend 50 miles from the center to the south.  The strongest winds I would guess are confined to the eyewall which may be ten miles wide or so.

This does not lessen the threat of flash-flooding.  Latest satellite estimates in the northern quadrant show some pockets of 1.25IN/hr rainfall rates in the northern quadrant.  Currently, Typhoon Lupit has equal convection on both the northern and southern quadrant so these rates can be expected to the south as well.  We’ll have a better idea with the next full overpass.

Nonetheless, a glancing blow would be considerably easier to handle for Filipinos than a direct impact.  So, obviously, it should be hoped Lupit can continue the current motion a little bit longer and/or not make as sharp a turn west-southwest as expected.

I think either case is plausible.

Caribbean Distrubance

Convection is firing along a stalled stationary front that is expected to dissolve soon.  This convection is anticipated by numerous models to develop into a tropical cyclone later this week.

The 20/0000Z CMC run develops the system Friday or Saturday, taking it inland into Honduras and over Nicaragua before back into the Caribbean at the 144-hour frame.

The 20/0600Z GFS run is not quite as aggressive but keeps a cyclone offshore Honduras towards the end of its 7-day forecast.

The 20/0000Z ECMWF develops the system further offshore in about five days and takes the system north across Cuba, Key West and up the eastern seaboard as a moderate tropical storm.

It should be noted any talk of development while entertaining is not worth it right now.  Latest CIMSS shear maps show westerly winds 20kts (23mph or 37kph) to 30kts (35mph or 56kph).  This shear should last for another 24 hours, at least.

Though it is interesting, we should wait until the shear decreases before considering what the system may do.  Even if it does develop, if it takes the path of the CMC or GFS, it won’t reemerge as a tropical cyclone.  The mountainous regions of Honduras and Nicaragua will severely disrupt inflow.

However, the ECMWF’s track, should that be the situation, would take the cyclone over an abundance of warm waters with high OHC values.

If a system survives the current shear and can find favorable atmospheric conditions, there is no question we could see a situation similar to what we just saw with Hurricane Rick.

Again, though, that’s a BIG IF.  We shall see what we shall see whenever we see it.