[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 121737
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN AUG 12 2012

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1700 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 26N34W TO 17N36W THROUGH A 1014 MB
SURFACE LOW ALONG THE AXIS AT 21N36W MOVING W AT 20 KT. THE
SATELLITE REPRESENTATION OF THE WAVE IS WELL-DEFINED WITH CLEAR
LOW-LEVEL CYCLONIC FLOW AROUND THE LOW CENTER. THE SYSTEM ALSO
COINCIDES WITH A CUT-OFF AREA OF DEEP MOISTURE PRESENT IN TOTAL
PRECIPITABLE WATER IMAGERY. HOWEVER...DRY AIR AND DUST SURROUND
THE WAVE LIMITING MOST DEEP CONVECTION. ONLY A SMALL AREA OF
MODERATE CONVECTION IS W OF THE LOW CENTER FROM 21N-22N BETWEEN
37W-38W.

TROPICAL WAVE...REMNANTS OF T.D. SEVEN...IS MOVING W AT 20 KT
THROUGH THE EASTERN CARIBBEAN FROM 19N64W TO 11N66W. SATELLITE
IMAGERY ALONG WITH SURFACE OBSERVATIONS INDICATE SHARP CYCLONIC
FLOW AROUND THE AXIS. THE WAVE ALSO LIES UNDERNEATH THE BASE OF
AN UPPER LEVEL TROUGH IN THE W ATLC...WHICH IS HELPING PRODUCE
SHOWERS/THUNDERSTORMS NEAR THE WAVE. A CLUSTER OF STRONG
CONVECTION IS FROM 14N-15N BETWEEN 63W-66W. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 12N-17N BETWEEN 66W-69W.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
SENEGAL AT 15N17W WHERE IT CONTINUES ACROSS ATLC WATERS ALONG
11N23W 14N31W. THE ITCZ BEGINS FARTHER W AT 10N42W AND CONTINUES
TO 10N59W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR
THE COAST OF AFRICA FROM 8N-12N BETWEEN 15W-21W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING COVERS THE MAJORITY OF THE GULF OF MEXICO
TODAY EXTENDS FROM THE W ATLC. SURFACE WINDS ARE LIGHT AND
ANTI-CYCLONIC AROUND THE RIDGE. THE SURFACE RIDGE IS ALSO
SUPPORTING MOSTLY FAIR WEATHER IN COMBINATION WITH DRY AIR ALOFT
PRESENT ACROSS THE NW HALF OF THE GULF. HOWEVER...AN UPPER LEVEL
TROUGH OVER THE EASTERN CONUS ALONG WITH AN UPPER LEVEL LOW OVER
THE COAST OF MEXICO NEAR 24N98W ARE PROVIDING MOISTURE ACROSS
THE SE HALF OF THE BASIN. THE UPPER TROUGH OVER THE EASTERN
CONUS SUPPORTS A WEAK COLD FRONT THAT EXTENDS FROM THE FLORIDA
PANHANDLE AT 31N84W ALONG 29N88W INTO LOUISIANA AT 30N91W.
ISOLATED SHOWERS ARE ALONG THE FRONT. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE ALSO ACROSS THE SE GULF FROM THE YUCATAN
CHANNEL TO CENTRAL FLORIDA. WEAK SURFACE RIDGING WILL REMAIN
ACROSS THE BASIN WITH A CHANCE OF SHOWERS/THUNDERSTORMS
REMAINING OVER THE SE HALF.

CARIBBEAN SEA...
AN UPPER LEVEL LOW OVER THE COAST OF MEXICO IN THE GULF OF
MEXICO IS PROVIDING DIFFLUENCE ALOFT OVER THE NW CARIBBEAN
SUPPORTING A FEW SHOWERS/THUNDERSTORMS OFF THE COAST OF THE
YUCATAN PENINSULA AND THROUGH THE YUCATAN CHANNEL. STRONG
SHOWERS/THUNDERSTORMS ACROSS ACROSS PORTIONS OF
NICARAGUA...COSTA RICA...AND PANAMA NEAR THE MONSOON TROUGH THAT
EXTENDS THROUGH SOUTHERN NICARAGUA TO NRN COLOMBIA ALONG 12N85W
10N79W 10N76W. THE CENTRAL CARIBBEAN IS MOSTLY DRY DUE TO DRY
AIR ALOFT WRAPPING AROUND AN UPPER LEVEL RIDGE OVER THE FAR W
ATLC...AND AN UPPER LEVEL INVERTED TROUGH WITH AXIS ALONG 71W.
THE EASTERN CARIBBEAN IS BEING IMPACTED BY AN ACTIVE TROPICAL
WAVE...REMNANTS OF T.D. SEVEN. THE WAVE AXIS IS WELL DEFINED AND
IS SUPPORTING SHOWERS/THUNDERSTORMS WITHIN AT LEAST 200 NM
EITHER SIDE OF THE AXIS. SOME OF THE ACTIVITY IS ENHANCED BY
DIFFLUENCE ALOFT AROUND AN UPPER LEVEL TROUGH IN THE CENTRAL
ATLC TO THE N. EXPECT SHOWERS/THUNDERSTORMS TO REMAIN NEAR THE
WAVE AS IT MOVES WESTWARD INTO THE CENTRAL CARIBBEAN.

ATLANTIC OCEAN...
AN UPPER LEVEL RIDGE COVERS THE W ATLC SUPPORTING A 1022 MB HIGH
NEAR 36N62W. HOWEVER...AN UPPER LEVEL TROUGH OVER THE EASTERN
CONUS IS HELPING SUPPORT A FEW SHOWERS/THUNDERSTORMS N OF 29N
BETWEEN 75W-78W...AND N OF 28N BETWEEN 69W-72W. A SECOND UPPER
LEVEL TROUGH IS FARTHER E FROM 34N54W TO 18N63W SUPPORTING
ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS FROM 25N-29N BETWEEN
53W-58W. AN UPPER LEVEL RIDGE IS TO THE E CENTERED NEAR 24N47W
SUPPORTING A 1026 MB HIGH CENTERED NEAR 33N35W. A WEAK UPPER
LEVEL SHORTWAVE TROUGH IS ALONG 35N32W TO 26N39W SUPPORTING A
FEW ISOLATED SHOWERS FROM 28N-31N BETWEEN 32W-37W. A TROPICAL
WAVE IS TO THE SOUTH...BUT IS CAUSING NO SIGNIFICANT WEATHER AT
THIS TIME. SEE TROPICAL WAVE SECTION FOR MORE DETAILS. VISIBLE
SATELLITE IMAGERY INDICATES AN AREA OF DUST EXTENDS FROM THE
COAST OF AFRICA AND IS WRAPPING AROUND THE N SIDE OF THE
WAVE...WHICH IS LIKELY INHIBITING CONVECTION NEAR IT.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON





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