Vigorous Tropical Waves/Watching The Tropics

[srainhoutx]

While the SAL (Saharan Arid Layer/African Dust) and sinking air due to High Pressure across the Eastern Atlantic is noticeable, a couple of robust tropical waves are marching West and a couple catch the eye as potential candidates for what the Global models are suggesting for possible development in about 10 days in the NW Caribbean/Gulf of Mexico. One wave is around 25 to 30 longitude and another convective ball is traveling behind it off the Coast of Africa. With an increasing chance of favorable conditions for Tropical Development the beginning of July, we will need to monitor those tropical waves as they enter the Caribbean Sea in about a week to see if convection begins to increase and wind shear becomes less hostile.

[srainhoutx]

A sharp tropical wave continues to march West in the mean Easterly flow just W of 40 Longitude this morning and has some convection rather far South along the Monsoonal Trough/ITCZ. Another vigorous wave is in the Western Caribbean Sea moving Westbound with some embedded strong tropical thunderstorms, but no development is expected.

The morning MJO data continues to advertise a strong pulse of rising air and favorable conditions spreading across the Eastern Pacific and the Western Caribbean and Gulf of Mexico as we begin July. We will need to monitor the tropical waves as the move West off Africa and across the Central Atlantic for any potential tropical mischief developing particularly as we end June and begin July in the Caribbean Sea and the Gulf.

[brooksgarner]

One thing we talked about at AMS Austin with reps from NCEP is that they expect the GFS to perform considerably better this hurricane season, due to the recent supercomputer enhancements and algorithm tweeks. It'll be telling if indeed, the GFS successfully has sniffed out development in the western Caribbean and Gulf in a few short weeks. Certainly the progress of the MJO coincides with GFS's long-range outlook for one of those tropical waves to develop. You've made a very good analysis in these posts!! Thank you.

[srainhoutx]

Beginning to see some rather impressive Ensemble support for the possibility of Tropical Cyclone Genesis across the NW Caribbean as the robust MJO pulse arrives. Also, the Day 11+ Analogs offer some interesting dates that coincide with a favorable Upper Air pattern during that time.

[brooksgarner]

Nice map! That ensemble makes sense. 12z gfs prog is a bit wild!

[brooksgarner]

From NOAA in weekly MJO discussion here: http://www.cpc.ncep.noaa.gov/products/p ... update.pdf

"Extratropical impacts of the MJO on the U.S. are likely to be limited. While an MJO
event over the Maritime Continent is usually consistent with suppressed tropical
cyclone activity over the Western Hemisphere, Kelvin Wave activity may contribute
to tropical cyclone formation near the Bay of Campeche during Week-2."

[srainhoutx]

Brooks and all, I have started a July Topic with the Afternoon Update from the Climate Prediction Center regarding the extended Day 8 to 14 Outlook. That Topic also has a link back here to Hurricane Central since it appears things may get just a bit busy in the Weather Department.


http://forums.khou.com/viewtopic.php?f=2&t=2104

[brooksgarner]

Thanks!

[BlueJay]

All of this talk about things getting weather-busy within the next two weeks should be a clear wake up call to get ready for hurricane season...

[Katdaddy]

The tropics awaken. Invest 95L near the Yucatan will move into the BOC during the next several days

[srainhoutx]

Morning analysis across the Atlantic Tropical Basin indicates a tropical wave in the Bay of Campeche and another nearing the Lesser Antilles. Further East over Africa, another vigorous wave is about to emerge off the Coast of Africa and traverse the Atlantic in the mean easterly flow beneath the sub tropical upper ridge. The MJO pulse continues to look rather healthy arriving in early July and conditions may well become conducive for tropical development for any tropical wave nearing the Western Caribbean Sea and potentially the Gulf of Mexico.

[srainhoutx]

Sunday morning analysis across the Tropical Atlantic as well as Hemispheric Pattern features suggest a vigorous Tropical Wave has exited the African Coast into the far Eastern Atlantic. There is some noticeable spin associated with the wave, but convection has decreased as the Saharan Arid Layer (African Dust) and the strong sub tropical Atlantic Ridge indicates sinking air, or subsidence which is prohibitive of allowing thunderstorms to develop at this time. At the surface as well as via mimic imagery, the 'spin' is clearly evident and should arrive in the Caribbean Sea in about 8 -10 days which coincides with the arrival of a Convectively Coupled Kelvin Wave and MJO pulse which means rising air and greater instability could increase across the Western Caribbean Sea and the Gulf of Mexico. While the Global models do not indicate any potential tropical development at this time, past experience suggests when tropical waves interact with the CCKW and MJO pulse, the potential exists for tropical development as tropical thunderstorms can organize in a better environment of rising air and greater instability. The GFS Super Ensembles do indicate an Upper Air Pattern of a Desert SW Ridge and a trough in the East that may allow a weakness between those upper air features to be in place over portions of the NW and Northern Gulf Coast. As always, we can not fully trust the computer models beyond the 3 to 5 day period but the Hemispheric pattern is suggesting there may be some potential for tropical mischief in a couple of weeks. We will continue to monitor and update as need be.

[brooksgarner]

Great update, and I concur.

[tireman4]

As usual Srain, great update.

[srainhoutx]

Tuesday morning Tropical analysis suggest the strong sub tropical ridge and its subsidence across the Main Development Region (MDR) continues as a couple of tropical waves move West in the mean Easterly surface flow. There is a bit more convection noticed today along the Inter Tropical Convergence Zone (ITCZ) and additional tropical waves are moving across Africa near 10 degrees latitude. African Dust or SAL continues to inhibit an influence over the Central Atlantic, but there are some indications that the West African Monsoon Season may begin in the next week or so and may decrease that Dust. An excellent tool I use and some will find it helpful as well, is Polar Orbiting Satellite imagery that provides a 48 hour loop of the Northern Hemisphere and shows the various weather features across the Globe, North of the Equator.

http://climate.cod.edu/flanis/satellite ... olar-wv-48

In the Pacific, the MJO pulse continues to advances East over the Pacific Ocean along with a rather robust Convectively Couple Kelvin Wave (CCKW) and the Global models are beginning to indicate possible tropical development in the Eastern Pacific as those Hemispheric features near Mexico next week. Rising air and increased instability could allow for tropical thunderstorms to congeal and organize in the Eastern Pacific Basin that has had no Tropical Cyclones to date. Typically this is one of the most active Basins around the Globe for Tropical Cyclones, but in a neutral ENSO State potentially near a weak La Nina it is understandable that TC's have not been able to organize with the cooler waters increasing off the Western South America Pacific Coast and higher wind shear.

[srainhoutx]

This morning a Tropical Disturbance in the Eastern Pacific just West of Guatemala may organize into the 1st Eastern Pacific Tropical Cyclone of the 2016 Pacific Season. This is rather late and we typically see 1 to 3 storms have formed by this date and it likely is indicative of the approaching MJO Pulse and Convectively Coupled Kelvin Wave that has been mentioned for over a week. The GFS is very aggressive developing multiple areas of surfaces low pressure systems while the ECMWF is a bit less aggressive, but does indicate the possibility of a TC organizing. The NHC is currently giving the tropical disturbance a 60% chance for developing over the next 5 days as it moves slowly West to West North West.

The attachment 06292016 5AM PDT two_pac_5d0.png is no longer available

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
500 AM PDT WED JUN 29 2016

For the eastern North Pacific...east of 140 degrees west longitude:

1. A broad area of low pressure is expected to form south of the Gulf
of Tehuantepec later this week in association with a westward-moving
tropical wave that is currently located south of Guatemala.
Environmental conditions are forecast to be conducive for gradual
development of the disturbance, and a tropical depression could
form over the weekend while the system moves generally westward or
west-northwestward at 10 to 15 mph, remaining well offshore of the
coast of Mexico.
* Formation chance through 48 hours...low...near 0 percent
* Formation chance through 5 days...medium...60 percent

Forecaster Stewart


In the Atlantic Basin, a vigorous tropical wave is about midway between Africa and the Lesser Antilles, but lacks convection and is pushing a swath of dry air out in front of it. There is a bit of spin indicated by Mimic as it remains attached to the ITCZ heading West.

Further East toward Africa, additional tropical waves continue to move across Africa and the Eastern Atlantic that will need to be monitored in the days ahead as the MJO Pulse and CCKW move across the Atlantic Basin and may bring conditions more favorable for tropical development as we begin July and particularly in about 10 to 12 days.

[srainhoutx]

Tropical wave activity continues to increase across the Tropical Atlantic, but SAL or African Dust and subsidence from the Sub Tropical Atlantic Ridge continues to keep convection in check E of 50 degrees Longitude. There is a TUTT low spinning near the SE Bahamas inducing wind shear across the Caribbean Sea and that feature will keep any tropical waves from gaining convection throughout the weekend into next week.

The robust Madden Julian Oscillation (MJO) Pulse continues its slow trek Eastbound and will likely assist in developing a couple of Tropical Cyclones in the Eastern Pacific over the next week or so as they safely move generally West away from land into the open Pacific. The Convectively Coupled Kelvin Wave appears somewhat stronger this morning over the Eastern Pacific lending to greater rising air and instability which will further assist in TC Genesis in the Eastern Pacific Ocean. Eventually around the mid July timeframe, those Hemispheric features will move far enough East to begin impacting the Western Atlantic Basin. Some of the longer range ensemble computer guidance suggest the Upper Ridge will retreat West over the SW United States and pressures begin to fall across the NW Caribbean Sea and the Western Gulf. We will continue to monitor for any potential tropical troubles as we begin the slow, but steady march toward peak Hurricane Season 2016 and hope all have a Safe and Happy Independence Day!

[srainhoutx]

From Levi Cowan:

Levi Cowan ‏@TropicalTidbits · 28m28 minutes ago
GFS short-term correction is toward a more vigorous tropical wave to move through Lesser Antilles on Monday:

[Ounce]

As a side question, is it normal for High pressure to encompass the whole North Atlantic Ocean in the Summer?

[srainhoutx]

As a side question, is it normal for High pressure to encompass the whole North Atlantic Ocean in the Summer?

Different years and different Hemispheric Patterns that can be very complicated tend to factor into the strength of the Azores Ridge and its impact on our sensible weather. One of the visual tools that I use to show the causal weather observer is the Analogs which is basically a 'snapshot in time' of similar weather patterns that may offer clues to what we may experience when similar pattern of past years have occurred. Todays Day 11+ Analogs via the Global Forecasting System Super Ensembles (American Models and its individual ensemble Members) suggest 1979 is a good fit for today looking out a couple of weeks. These analogs vary daily, but are a good general snapshot in time of when Northern Hemispheric Patters were somewhat similar.