[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 112301
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI AUG 11 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2300 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG THE W COAST OF AFRICA ALONG 15W S OF
21N MOVING W NEAR 10 KT. THIS WAVE HAS A FAIR AMOUNT OF
SIGNATURE EVIDENT ON SATELLITE IMAGERY AND IS GENERATING SMALL
CLUSTERS OF MODERATE CONVECTION FROM 12N-17N BETWEEN 13W-19W.
EVEN THOUGH THIS WAVE HAS NOT YET PULLED OFF THE CONTINENT THERE
IS GOOD CONFIDENCE IN THIS ANALYZED POSITION BASED UPON THE
AVAILABLE SFC DATA AND SATELLITE IMAGERY WHICH SHOWS A CLASSIC
WAVE STRUCTURE. IN ADDITION...GLOBAL MODELS HAVE THIS WAVE
INITIALIZED WELL AND TRACK IT OFFSHORE TONIGHT EVENTUALLY
PICKING UP FORWARD SPEED AS IT MOVES UNDER A LOW-MID LEVEL RIDGE.

A TROPICAL WAVE IS ALONG 48W/49W S OF 19N MOVING W NEAR 15 KT.
THIS WAVE REMAIN WELL DEFINED AND FAIRLY HIGH AMPLITUDE WITH A
LOW-MID LEVEL SWIRL EVIDENT ON THE AXIS NEAR 13N. THIS WAVE HAS
BEEN EMBEDDED IN A VERY DRY ENVIRONMENT OVER THE PAST FEW DAYS
SUPPRESSING ANY SIGNIFICANT CONVECTION. THERE WAS A LITTLE MORE
WEATHER ASSOCIATED WITH IT THIS AFTERNOON BEFORE FALLING APART
THIS EVENING. SCATTERED SHOWERS ARE MAINLY AHEAD OF THE WAVE
AXIS FROM 11N-14N BETWEEN 49W-55W.

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 72W S OF 21N
MOVING W 15-20 KT. THIS WAVE LOOKS A LITTLE MORE ACTIVE TODAY
THAN IT WAS YESTERDAY PRODUCING SCATTERED MODERATE CONVECTION
FROM 15N-18N BETWEEN 70W-73W. THE STRUCTURE OF THIS WAVE HAS
ALSO IMPROVED SLIGHTLY WITH SOME LOW-MID LEVEL CYCLONIC TURNING
EVIDENT NEAR THE WAVE AXIS. UPPER LEVEL WINDS DO NOT APPEAR
FAVORABLE FOR FURTHER DEVELOPMENT AS AN UPPER LOW IS LOCATED 300
NM TO THE NE OF THE WAVE AND WILL BE MOVING WWARD IN TANDEM.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 13N17W 9N32W 12N47W TO INLAND OVER S
AMERICA NEAR 10N62W TO PANAMA NEAR 9N81W. BESIDES FOR THE
TROPICAL WAVES...SCATTERED SHOWERS AND ISOLATED TSTMS ARE
WITHIN 60 NM OF THE AXIS E OF 27W. A PATCH OF SCATTERED SHOWERS
AND TSTMS ARE FROM 7N-11N BETWEEN 36W-41W. SCATTERED MODERATE
TO STRONG CONVECTION IS WITHIN 240 NM OF THE AXIS W OF 71W
EXTENDING ACROSS N COLOMBIA AND PANAMA INTO THE E PACIFIC.

...DISCUSSION...
GULF OF MEXICO...
QUIET WEATHER PERSISTS ACROSS THE CENTRAL AND EASTERN GULF OF
MEXICO UNDER THE INFLUENCE OF BROAD UPPER RIDGING WHICH EXTENDS
ACROSS THE SRN U.S. WITH ONE ANTICYCLONE CENTERED OFF THE FL/GA
COAST NEAR 31N80W. PLENTY OF DRY/STABLE AIR COVERS THE REGION E
OF 90W SUPPRESSING ANY ORGANIZED CLOUDINESS OR SHOWERS. THE ONLY
AREA OF SOME ACTIVITY IS IN THE W GULF ASSOCIATED WITH AN UPPER
LEVEL LOW WHICH IS CURRENTLY ALONG THE TEXAS/MEXICO BORDER NEAR
26N97W. THIS UPPER LOW HAS BEEN BECOMING INCREASINGLY LESS
ACTIVE AS IT TRACKED ACROSS THE GULF NOW WITH ONLY ISOLATED TO
SCATTERED SHOWERS SPIRALING AROUND IT W OF 93W FROM 23N-28N. A
PATCH OF MODERATE CONVECTION IS MOVING OFF THE YUCATAN PENINSULA
INTO THE BAY OF CAMPECHE FROM 18N-20N BETWEEN 89W-92W. AT THE
SURFACE...WEAK HIGH PRES RIDGING IS LOCKED INTO THE REGION
STRETCHING FROM THE ATLC ACROSS THE GULF. MODELS ANTICIPATE THIS
SFC PATTERN TO CHANGE LITTLE THIS WEEKEND KEEPING CONDITIONS
FAIRLY TRANQUIL. THE NEXT CHANCE OF ANY ORGANIZED MOISTURE WILL
BE LATE THIS WEEKEND INTO EARLY NEXT WEEK AS THE TAIL END OF A
FRONTAL BOUNDARY DIPS SWD ACROSS THE NE GULF AND AS THE CENTRAL
CARIBBEAN WAVE APPROACHES THE SRN PORTION OF THE AREA.

CARIBBEAN SEA...
THE MAIN FEATURE IN THE AREA IS A TROPICAL WAVE IN THE CENTRAL
CARIBBEAN. THIS WAVE SHOWED SOME SIGNS OF ORGANIZING ON WED
BEFORE BECOMING VERY SHEARED AND ILL-DEFINED ON THU. TODAY...THE
WAVE IS SLIGHTLY MORE ACTIVE THAN YESTERDAY TRIGGERING SCATTERED
MODERATE CONVECTION FROM 15N-20N BETWEEN 70W-74W. SEE TROPICAL
WAVES SECTION FOR MORE DETAILS.  SCATTERED MODERATE CONVECTION
IS OVER PORTIONS OF CENTRAL AMERICA FROM 11N-16N BETWEEN 84W-87W
AND OVER THE YUCATAN PENINSULA FROM 18N-20N BETWEEN 89W-92W.
SCATTERED MODERATE TO STRONG CONVECTION LIES OVER PORTIONS OF
COLOMBIA...PANAMA AND SRN COSTA RICA LIKELY CONTRIBUTED TO THE
ITCZ. TRADES ARE GENERALLY IN THE 15-25 KT RANGE ACROSS THE AREA
WITH STRONGEST WINDS BETWEEN THE COASTS OF VENEZUELA/COLOMBIA TO
HISPANIOLA WHERE THE PRES GRAD IS THE TIGHTEST. IN THE UPPER
LEVELS...AN ILL-DEFINED UPPER HIGH IS CENTERED IN THE W
CARIBBEAN NEAR 17N87W. AN UPPER LOW IS LOCATED TO THE N OF THE
MONA PASSAGE NEAR 21N68W WITH ITS TROF DIPPING TO 14N70W. THE
REMAINDER OF THE REGION HAS E-NE UPPER LEVEL FLOW WITH PLENTY OF
DRY/STABLE AIR.

ATLANTIC OCEAN...
A VERY BROAD UPPER RIDGE EXTENDS ACROSS THE SRN U.S. STRETCHING
OUT TO 62W. UPPER DIFFLUENCE BETWEEN THIS RIDGE AND A STRONG
UPPER TROUGH TO ITS N AND ITS ASSOCIATED SFC FRONT IS PRODUCING
SCATTERED SHOWERS AND TSTMS N OF 29N W OF 62W. A NEARLY
STATIONARY 1014 MB LOW IS LOCATED NEAR 33N35W WITH A SFC TROUGH
DRAPING SWARD FROM THE LOW TO 30N35W THEN SWWARD TO 27N39W. THIS
LOW IS EMBEDDED IN A VERY DRY ENVIRONMENT ONLY PRODUCING A FEW
SHOWERS WITHIN 150 NM OF THE CENTER. ANOTHER UPPER LOW IS
LOCATED TO THE N OF THE MONA PASSAGE NEAR 21N67W. THIS LOW IS
ALSO A RATHER DRY FEATURE PRODUCING VERY LITTLE WEATHER. MUCH OF
THE E AND CENTRAL ATLC IS COVERED BY AN UPPER RIDGE WITH
MODERATE TO STRONG SUBSIDENCE ABOVE THE MAJORITY OF THE AREA
LIMITING ANY ORGANIZED CLOUDINESS OR SHOWER ACTIVITY. AT THE
SFC...HIGH PRES RIDGING CONTINUES TO BE THE THEME WITH THE SFC
RIDGE AXIS EXTENDING FROM A 1020 MB HIGH IN THE E ATLC NEAR
28N30W TO A 1018 MB HIGH IN THE CENTRAL ATLC NEAR 24N54W
STRETCHING ACROSS SOUTH/CENTRAL FLORIDA.

$$
CANGIALOSI




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