May 31 2005 – 01:00 UTC

The tropics remain quiet in the EPAC and Atlantic basins. The Atlantic season officially begins on June 1. In the WPAC, things have become a little more alive. TS 4-W has developed southeast of Guam, and is moving WNW. Strengthening into a typhoon is likely, though it poses no immediate threat to land at this time. Beyond 5 days, it could near the northern portion of the Philipinnes.

May 24 2005 – 00:00 UTC

Long-range forecast models are not indicating any TC formation in the next 5-6 days anywhere in the world. With a wet MJO slowly but surely building in the Indian Ocean, this could change beginning with the WPAC in the next week or so. As of now, things are quiet.

May 23 2005 – 00:00 UTC

The tropics are quiet worldwide. Strong upper level winds and a lack of any disturbances are preventing anything from forming in the EPAC in the wake of Adrian. Enjoy it while you can. The Atlantic season begins in 9 days, and our 2005 Atlantic hurricane season forecast is geared to be released this Wednesday.

May 22 2005 – 00:00 UTC

The remains of Adrian are moving across the Bahamas with some squally weather, but there is no chance of redevelopment. Seasonably strong upper level winds dominate the Atlantic and East Pacific basins, preventing anything from organizing in the mean time. The tropics across the world are very quiet, and there are no signs of tropical cyclone formation over the next few days.

May 20 2005 – 23:00 UTC

Hurricane Adrian hit the coast of El Salvador late last night with maximum sustained winds of 75MPH. As the center moved into the mountainous terrain of Central America, the storm lost all of its energy and rapidly dissipated by the afternoon. The remnants of Adrian are now moving through the NW Caribbean Sea, but redevelopment is being inhibited by strong upper level shear evident over the area. A continued NE motion of the remain low through Cuba and the Bahamas is likely, bringing some showers and gusty winds but nothing significant.

Now that Adrian is out of the picture, the worldwide tropics is once again quiet. A wet phase MJO is building in the Indian Ocean and geared to progress east over the next few weeks. We’re getting closer to the time of the year where these can enhance TC activity across the Pacific (particularly WPAC). In the near term, however, all is calm and there are no tropical development threats at this time.

May 19 2005 – 22:00 UTC

TPC reconnaissance aircraft investigated Tropical Storm Adrian earlier today, and found that it was already at hurricane strength. Sustained winds are 85mph making it a Category One on the Saffir Simpson Scale. While sustained winds have “officially” increased within the last six hours, Adrian’s intensity has probably been about the same over the last 24 hours. There were no surface observations to verify the storm’s intensity before recon went in. The hurricane has begun to show signs of elongation. The aforementioned upper level trough positioning itself in the Gulf of Mexico is beginning to increase southwest winds to 20-30 knots aloft. Normally these winds would begin to weaken a tropical cyclone, but Adrian is within the geostrophic flow. The cyclone will likely remain at or near the same intensity until it makes landfall. Severe flooding and mudslides due to 10-20 inches of rainfall is still the primary threat.

Once over the western Caribbean Sea, the surface circulation will have already taken a tremendous beating due to the mountainous terrain of Central America. Furthermore, the system may begin to acquire subtropical and eventually extratropical characteristics as the trough’s influence becomes more substantial. Regardless, the storm’s effects on Cuba, Haiti, and The Bahamas will be the same. Several inches of rainfall are expected, but the threat of flooding is not nearly as significant as it is in Central America.

May 18 – 23:00 UTC

Tropical Storm Adrian was upgraded last evening, and has gradually intensified since the previous discussion. At noon, visible satellite imagery began to show hints of an eye-like feature, but the clearing near the center of the Central Dense Overcast (CDO) has recently become cloud filled. Sustained winds are likely 60-65mph, which is in agreement with TPC’s latest analysis. Adrian will have another 24 hours to strengthen prior to landfall, but upper level winds are expected to increase, and only limited intensification is expected. The storm still has the potential to intensify into a Category One Hurricane, but the window of oppurunity is beginning to close. Tropical storm force winds at landfall is more likely.

The synoptic pattern is evolving as forecast. An upper level trough is carving out a strong southwest flow in the Gulf of Mexico that extends well into the western and central Atlantic Ocean. Adrian has been quite easy to forecast considering that it is such a climatologically unfavored cyclone. Landfall will occur tomorrow evening along southeast Guatemala, El Salvador, and northern Nicaragua. But the threat does not cease at the coast. The worst of the flooding and mudslides will likely develop in the interior sections of the aforementioned countries.

The remnant of Adrian will enter the northwest Caribbean Sea in a couple days. Sea surface temperatures are warm enough for regeneration, but the stalled trough over the southeast Gulf of Mexico will likely limit development. Cuba can expect a very rainy period starting Saturday and lasting possibly into Tuesday. Southern Florida may also experience an increase in rain chances, but flooding is not expected to be a major issue. The bulk of activity will remain to the south.

Elsewhere, the tropics are quiet.

May 17 – 21:00 UTC

INVEST 90-E has continued to organize throughout the day and is now Tropical Depression One-E, the first of the very young EPAC season. Satellite imagery depicts very healthy banding features associated with TD1-E. The strong southwesterly shear some distance to the north is now actually enhancing outflow in the northern section of the storm. The convective pattern, while ragged, is expected to improve overnight during diurnal maximum.

500-850MB steering layers suggest a northeasterly motion due to a large trough to the north. This is in agreement with all of the global models, which have been insistent on such a track over the past several days. The model consensus is, and has been, extremely converse on a landfall along the Guatemala/El Savador coast in approximately 48HR lead time. Given such a strong and persistent model agreement, combined with its obvious logic when looking at the synoptic pattern…there is no reason to believe that a track otherwise will occur. Conditions will remain favorable for further strengthening over the next day or so while over water. Reaching TS status (the first name on the list is Adrian) is almost a sure bet. The big question is exactly how strong the system will get before it hits. The often-overagressive GFDL model brings it to a category 4, whereas SHIPS takes it to a strong TS. Out of the global models, GFS and UKMET show the most intensification, the NOGAPS being the weaker. The most recent NOGAPS run can be discared because it poorly initializes the system in the first place. Given the obviously favorable environment and currently healthy organization…there is a good chance that this will become a hurricane before landfall, and rapid intensification cannot be entirely ruled out. Some weakening just a few hours up to landfall may occur as depicted by some of the models as it begins to lose its source of energy and gets too close to high mountainous terrain. However, any last minute weakening will not diminish the likelihood of life-threatening flash flooding and mudslides. It should be noted that Central America has never been hit by a TS (or hurricane) from the west in the 56 years of EPAC record-keeping.

Moving over mountainous Central America will weaken the system below TS/TD strength and nearly, if not completely, destroy the system’s core. However, many of the global models are in agreement on its low vorticity and energy spreading into the NW Caribbean Sea. The GFS actually seems to develop (or redevelop) a weak TC in this region from TD1-E/Adrian’s remnants and takes it through Cuba. The main inhibiting factor for redevelopment once in the Caribbean will be strong UL shear. If any classified storm does form in the Caribbean from the remnants, it would almost surely be weak and baroclinically-forced by the shear. Chances for even that are low, but it is something that will be monitored.

The rest of the globe is otherwise quiet. INVEST 96W has basically dissipated and is no longer suspect to development.

May 17 2005 – 00:00 UTC

Showers and thunderstorms are beginning to consolidate near an area of low pressure located near 10ºN and 96ºW. SSMI data is not available for this region at this time, but visible satellite imagery clearly shows what looks to be a low to mid level circulation in the early stages of development. Upper level winds are favorable for further intensification due to a strong upper level ridge of high pressure in place. I see no reason to believe that development will not occur within the next 72 hours.

Over the next three to four days, the 500MB pattern will shift over the United States. An upper level ridge will strengthen over the western states, and a deeper trough will dive south into the Gulf Coast. The GFS develops a strong upper low in the Midwest, and then dives it south into the central gulf Coast states by 96-120 hrs. This upper level low and associated trough will create an extensive weakness over the Gulf of Mexico, Central America, and western Caribbean Sea. All global models further develop the eastern Pacific low pressure area before being drawn into Guatemala, El Salvador, Honduras, and Belize. In fact, current steering layer winds already support an easterly track. Such a path is extremely rare, and it has not occured in recent history, but that does not mean it cannot happen. These areas must be ready for flash flooding, especially in mountanious areas that are prone to mudslides. Several inches of rainfall is likely.

Recent satellite imagery, upper level winds, and model guidance all suggest that the possibility of a moderate tropical storm development just offshore is good. With that being said, it is still unlikely that such a storm would survive its trip across land and enter the western Caribbean without weakening significantly. In fact, the GFS significantly weakens the tropical cyclone by the time it reaches the coast. That does not mean regeneration is not possible if decent upper level conditions are in place. Furthermore, there is always the possibility of another surface low being spawned to the east (Caribbean Sea) of the current system. But until there is evidence of that happening in the medium range the point is moot.

While convection is still flaring in the Caribbean Sea, the the probability of 90L INVEST developing into a classified tropical cyclone is still low. Upper level southwest winds are still very strong, and they are not expected to diminish in the near future.

May 16 2005 – 00:00 UTC

A broad area of low pressure has begun to organize near 9.5ºN/98ºW. Visible satellite imagery shows a well defined low to mid level circulation with thunderstorms wrapping around the center. CIMSS Upper Level Wind Data shows an upper level ridge extending as far west at 130ºW along 10ºN. This ridge of high pressure will prevent any upper level troughs from impacting the low level circulation with strong southwest winds. There is the potential for slow intensification with these conditions in place.

The GFS model has demonstrated run to run consistency with developing a tropical storm in this area, and then turning it towards the northeast towards Central America. Typically, such a model forecast would be ignored since such a track has never occured in recent history. However, the UKMET has periodically shown the same exact scenario. Furthermore, the latest 18Z run of the NOGAPS model is beginning to trend in the same direction.

This entire area will need to be monitored over the next several days.

Meanwhile, 91L INVEST is still being monitored in the central Caribbean Sea. An upper level ridge is beginning to develop, and ventilate the southwest Caribbean. However, the broad area of low pressure is already beginning to move northeast along an upper level trough. The low pressure area will likely remain in an unfavorable environment for tropical cyclogenesis. The flash flooding threat continues for much of the central and eastern Caribbean.

A Tropical Cyclone Formation Alert has been issued by the Joint Typhoon Warning Center for the tropical disturbance near the southern Philippines. None of the numerical weather prediction models are initializing the low very well, but there is the potential for some development. More information on this system can be found on IWIC’s main page.

May 15 – 05:00 UTC

Today marks the “official” start of the 2005 Eastern Pacific Hurricane Season. On average, one can anticipate the formation of two tropical cyclones in the eastern Pacific during the month of May. At least one tropical storm has formed during May each year since 2000.

A broad surface trough extends from 80ºW to 110ºW longitude at 10ºN latitude. Upper level winds are less than 20 knots, and sea surface temperatures are well above 80ºF/26ºC in this area. Conditions are relatively favorable for tropical cyclone formation, but there are no organized areas of low pressure at this time. 12Z model guidance does not suggest that tropical development is imminent within the next five days.

Elsewhere, upper level winds are very hostile for development west of 115ºW.

Tropical storm formation is not expected in the eastern Pacific over the next 72 hours.

Meanwhile, the start of the Atlantic hurricane season begins June 1. There are no signs of tropical development at this time. However, 91L INVEST is present over the central Caribbean Sea. Upper level winds are too strong for immediate development, but flash flooding is a concern for the Greater Antilles. This area will be monitored over the next several days.

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