Low level twist at 45ºW

[Ed Mahmoud]

Sure, it is completely devoid of convection. But that is Hurricane Season 2009.



And it is in the oceanic equivalent of a desert.



But staring intently at the models, especially 850 mb vorticity fields (hard to do, it is so weak) this may be the genesis for the weak and sheared tropical wave, with almost no surface reflection, that is producing some scattered showers in the Western Gulf of Mexico in just one week!





If we do get rain in Texas in 7 or 8 days, well, just because it isn't a tropical cyclone, doesn't mean it isn't tropical weather.

[Sanibel]

Good. I felt lonely being the only one to bust loudly on the board


I heard two booms and the house shook. So I Googled and saw that the shuttle was landing. Cool.

[Ed Mahmoud]

OK, highlt respected mesoscale tropical model NAM sees the wave, with showers and a noticeable yet gentle curve in the isobars, approaching the islands in two days!



Where the showers come from, well, the model is performing millions of calculations that would take me decades to perform, but it shows showers.



3 days:
Passing Puerto Rico


84 hours- as if it could get more subtle- it does, but I thik showers approaching Hispaniola are my convectionless twist in the low clouds near 45ºW




12Z GFS- if you really try, you can see the subtle change in orientation of the 850 mb isotachs near this.

[floridasun78]

sal is winnng war not allowing any wave to become strong in atlantic other thing i heard too that NAM not good for tropical system

[srainhoutx]

Sure, it is completely devoid of convection. But that is Hurricane Season 2009.



And it is in the oceanic equivalent of a desert.



But staring intently at the models, especially 850 mb vorticity fields (hard to do, it is so weak) this may be the genesis for the weak and sheared tropical wave, with almost no surface reflection, that is producing some scattered showers in the Western Gulf of Mexico in just one week!





If we do get rain in Texas in 7 or 8 days, well, just because it isn't a tropical cyclone, doesn't mean it isn't tropical weather.

Brownsville mentions your feature...snipet...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
145 PM CDT FRI JUL 31 2009

.DISCUSSION...AN UPPER LEVEL HIGH PRESSURE SYSTEM CONTINUES TO
DOMINATE THE AREA TODAY PROMPTING A HEAT ADVISORY UNTIL 8 PM THIS
EVENING. WINDS HAVE DECREASED OVER THE AREA TODAY AS THE PRESSURE
GRADIENT HAS RELAXED. THE WEEKEND WILL CONTINUE TO BE HOT AND DRY
WITH VERY LITTLE CHANGE IN THE FORECAST. THE HUMIDITIES MIGHT
DECREASE ENOUGH DURING THE WEEKEND FOR CONDITIONS TO BE JUST UNDER
HEAT ADVISORY CRITERIA. BRO SOUNDING THIS MORNING SHOWED A PRECIP
WATER OF 1.59 AND A K-INDEX OF 18. TEMPERATURES AND MOISTURE WILL
INCREASE IN THE UPPER LEVELS BY MONDAY CAUSING POSSIBLE SEA BREEZE
TYPE SHOWERS OR THUNDERSTORMS DURING THE DAYTIME HOURS. LONG TERM
PROGS INDICATE POSSIBLE TROPICAL WAVE BY THE END OF NEXT WEEK
CAUSING THE CHANCES FOR SHOWERS AND THUNDERSTORMS TO INCREASE.&&