[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180602
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT AUG 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0545 UTC.

...SPECIAL FEATURES...

TROPICAL STORM HELENE IS CENTERED NEAR 21.2N 96.4W AT 18/0600
UTC OR ABOUT 57 NM ENE OF TUXPAN MEXICO AND ABOUT 102 NM SE OF
TAMPICO MEXICO MOVING NW AT 6 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH
GUSTS TO 45 KT. THE BROAD CYCLONIC WIND FIELD RELATED TO HELENE
IS GENERATING SCATTERED SHOWERS AND TSTMS S OF 23N W OF 90W. SEE
LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY UNDER
AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.

TROPICAL STORM GORDON IS CENTERED NEAR 34.0N 41.5W AT 18/0600
UTC OR ABOUT 742 NM WSW OF THE AZORES MOVING E AT 15 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. MAXIMUM SUSTAINED
WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 32N-37N BETWEEN 38W-43W. SEE LATEST
NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT3/WTNT33 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.

A TROPICAL WAVE IS LOCATED IN THE ERN ATLC EXTENDING FROM 18N22W
TO A 1009 MB LOW NEAR 11N25W...EMBEDDED WITHIN THE MONSOON GYRE
DESCRIBED BELOW. SCATTERED SHOWERS AND THUNDERSTORMS ARE FROM
10N-15N BETWEEN 23W-28W...WITHIN THE BROAD CONVECTIVE REGION
ASSOCIATED TO THE MONSOON TROUGH. SLOW DEVELOPMENT OF THIS WAVE
IS POSSIBLE DURING THE NEXT FEW DAYS AS IT MOVES TOWARD THE WEST
AT 13 TO 17 KT. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

...TROPICAL WAVES...

TROPICAL WAVE MOVES ACROSS THE CENTRAL TROPICAL ATLC WITH AXIS
EXTENDING FROM 19N41W TO 10N40W MOVING W AT 15-20 KT. THE WAVE
REMAINS EMBEDDED WITHIN A BROAD AREA OF ENHANCED DEEP LAYER
MOISTURE AS NOTED ON THE TOTAL PRECIPITABLE WATER IMAGERY. THE
NRN HALF OF THE WAVE AXIS HAS NO CONVECTION DUE TO A LARGE DRY
AIRMASS ASSOCIATED WITH THE SAHARAN AIR LAYER. ANY SHOWER
ACTIVITY OVER THE SRN EXTENSION OF THE WAVE AXIS IS LIKELY
ASSOCIATED TO THE BROAD MONSOONAL GYRE.

TROPICAL WAVE MOVES ACROSS THE ERN CARIBBEAN WITH AXIS EXTENDING
FROM 21N65W TO 13N64W MOVING W AT 15-20 KT. SCATTERED SHOWERS
AND ISOLATED THUNDERSTORMS ARE N OF 13N BETWEEN 63W-69W. A
LOW-LEVEL CYCLONIC FLOW IS NOTED OVER THE SRN PORTION OF THE
WAVE AXIS AND IS EXPECTED TO RESULT IN INCREASED CLOUDINESS AND
PRECIPITATION ACROSS HISPANIOLA THROUGH THE WEEKEND.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF SENEGAL...
ABOUT 30 NM N OF DAKAR TO 18N20W...RESUMING FROM THE SPECIAL
FEATURE 1012 LOW PRESSURE SYSTEM NEAR 11N25W ALONG A WEAK 1013
MB LOW NEAR 10N36W TO 8N44W. THE ITCZ AXIS BEGINS FORM THIS
POINT TO THE COAST OF FRENCH GUIANA NEAR 5N53W. A BROAD AREA OF
SCATTERED MODERATE CONVECTION COVERS FROM 5N-14N BETWEEN 24W-45W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SURFACE RIDGING IS NOTED ACROSS MOST OF THE DISCUSSION AREA
THIS MORNING...CENTERED AROUND A 1016 MB HIGH NEAR 26N91W. BROAD
UPPER LEVEL ANTICYCLONIC OUTFLOW FROM TROPICAL STORM HELENE
COVERS MOST OF THE GULF ON WATER VAPOR IMAGERY. DESPITE THESE
CONDITIONS AT SURFACE AND ALOFT...MID TO UPPER LEVEL CLOUDINESS
WITH A FEW ISOLATED SHOWERS COVER A GREAT PORTION OF THE NE AND
N-CENTRAL GULF...ASSOCIATED TO THE SRN EXTENSION OF A BROAD
UPPER LEVEL TROUGH MOVING OFF THE ERN CONUS SEABOARD. TROPICAL
STORM HELENE CONTINUES TO IMPACT THE WRN BAY OF CAMPECHE AS IT
MAKES IT'S WAY INLAND NEAR THE CITY OF TAMPICO MEXICO THIS
MORNING. THE BROAD CYCLONIC WIND FIELD RELATED TO HELENE IS
GENERATING SCATTERED SHOWERS AND TSTMS S OF 23N W OF 90W. WINDS
WILL REMAIN MODERATE TO FRESH IN THIS REGION DURING THE NEXT 24
HOURS.

CARIBBEAN SEA...
SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS ARE NOTED
ACROSS THE SW CARIBBEAN S OF 12N W OF 75W...ESPECIALLY IN THE
VICINITY OF THE MONSOON TROUGH ANALYZED OVER INLAND PORTIONS OF
CENTRAL AMERICA FROM NRN COLOMBIA TO COSTA RICA. WATER VAPOR
SHOWS AN UPPER LEVEL INVERTED TROUGH MOVING ACROSS THIS AREA
ENHANCING THE CONVECTION NEAR THE MONSOON TROUGH. SIMILAR
CONVECTION IS NOTED OVER THE ENE CARIBBEAN N OF 13N BETWEEN
63W-69W...ASSOCIATED WITH THE PASSAGE OF A TROPICAL WAVE. THE
SRN EXTENSION OF AN UPPER LEVEL TROUGH AXIS CROSSES HISPANIOLA
PRODUCING A SMALL CLUSTER OF SCATTERED SHOWERS OVER THE WINDWARD
PASSAGE...CLOSE TO THE WRN COASTAL WATERS OF HAITI. SOME
NOCTURNAL DRAINAGE AND SEA BREEZE CONVERGENCE PRODUCED SOME WEAK
SHOWERS MOVING OFF THE SRN COAST OF CUBA AND WRN JAMAICA...
EXPECTED TO DISSIPATE LATER THIS MORNING. THE REMAINDER OF THE
CARIBBEAN IS DOMINATED BY DRY AIR AND SUBSIDENCE ALOFT NOTED ON
WATER VAPOR IMAGERY.

ATLANTIC OCEAN...
WATER VAPOR SHOWS A BROAD UPPER LEVEL TROUGH MOVING OFF THE ERN
CONUS SEABOARD THIS MORNING. WEAK TO MODERATE DIFFLUENCE ALOFT
FROM THIS UPPER LEVEL FEATURE IS GENERATING SCATTERED SHOWERS
AND THUNDERSTORMS ACROSS THE WRN ATLC DISCUSSION AREA N OF 25N W
OF 72W. ELSEWHERE ACROSS THE REMAINDER OF THE CENTRAL AND
EASTERN ATLC...A BROAD SURFACE RIDGE COVERS THE AREA ANCHORED BY
A 1022 MB HIGH CENTERED NEAR 27N55W...EXTENDING A RIDGE AXIS
WESTWARD ALONG 25N INTO THE GULF OF MEXICO...AND A RIDGE AXIS
EASTWARD TO 25N23W. ALSO...THE SAHARAN AIR LAYER AND ASSOCIATED
DUST IS FURTHER MAINTAINING STABLE CONDITIONS ACROSS THE
DISCUSSION AREA E OF 62W.

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

$$

GARCIA




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