[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 282358
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT JUL 28 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2245 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 19N46W TO 10N51W MOVING W NEAR 20 KT.
TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT THE WAVE LIES
WITHIN A SURGE OF DEEP LAYER MOISTURE WITH MAXIMUM VALUES NEAR
THE AXIS. THERE IS ALSO A CLEARING IN THE WIDESPREAD SAHARAN AIR
LAYER THAT IS PRESENT ACROSS MUCH OF THE TROPICAL ATLC. AN ASCAT
SCATTEROMETER PASS FROM EARLIER TODAY ALSO INDICATES LOW LEVEL
CYCLONIC FLOW IS AROUND THE WAVE AXIS. DUE TO THE LARGE AREA OF
DUST NEAR THE WAVE...NO DEEP CONVECTION IS NEAR THE AXIS BESIDES
A SMALL CLUSTER NEAR THE NRN EXTENT OF THE WAVE.

TROPICAL WAVE IS MOVING W THROUGH THE E CARIBBEAN ALONG 18N64W
TO 11N67W AT 20 KT. THE WAVE IS MOVING THROUGH A VERY DRY
ENVIRONMENT DUE TO THE SURROUNDING DUST. HOWEVER...THE WAVE DOES
ALIGN WITH A LOW-AMPLITUDE SURGE OF DEEP LAYER MOISTURE PRESENT
IN TOTAL PRECIPITABLE WATER IMAGERY THAT EXTENDS TO ABOUT 15N. A
SMALL AREA OF MODERATE CONVECTION IS W OF THE WAVE AXIS FROM
14N-15N BETWEEN 67W-69W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS ALSO OVER INLAND VENEZUELA E OF THE AXIS.

TROPICAL WAVE PREVIOUSLY IN THE BAY OF CAMPECHE HAS NOW
DISSIPATED OVER INLAND MEXICO.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
SENEGAL AT 14N17W CONTINUING ACROSS ATLC WATERS THROUGH A 1011
MB SURFACE LOW AT 9N26W TO 11N39W 12N47W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS AROUND THE CIRCULATION OF
THE SURFACE LOW FROM 7N-10N BETWEEN 18W-27W...AND FROM 7N-12N
BETWEEN 27W-35W.

...DISCUSSION...

GULF OF MEXICO...
SHOWERS AND THUNDERSTORMS DOT MUCH OF THE NORTHERN GULF OF
MEXICO COAST FROM LOUISIANA TO FLORIDA ASSOCIATED WITH AN UPPER
LEVEL TROUGH THAT EXTENDS ACROSS THE EASTERN CONUS TO THE N
CENTRAL GULF. THE UPPER TROUGH IS ALSO SUPPORTING A WEAK SURFACE
TROUGH THAT EXTENDS FROM 31N84W TO 28N87W. AN UPPER LEVEL LOW IS
ALSO OVER THE SW GULF CENTERED NEAR 23N94W SUPPORTING A FEW
WIDELY ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE SW GULF AND THE
YUCATAN PENINSULA. THE REMAINDER OF THE BASIN IS DOMINATED BY A
SURFACE RIDGE AROUND A WEAK 1021 MB HIGH CENTERED NEAR 28N93W.
LIGHT ANTI-CYCLONIC FLOW IS AROUND THE HIGH. DRY AIR ALOFT IS
COVERING MOST OF THE CENTRAL PORTIONS OF THE GULF...WHICH IS
CONTRIBUTING TO THE FAIR CONDITIONS PRESENT. EXPECT LITTLE
CHANGE OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
THE ENTIRE CARIBBEAN REMAINS MOSTLY DRY AS IT IS IMPACTED WITH
SAHARAN DUST AND DRY AIR ALOFT...DESPITE THE PRESENCE OF A
TROPICAL WAVE OVER THE ERN CARIBBEAN. SEE SPECIAL FEATURES ABOVE
FOR MORE DETAILS. AN UPPER LEVEL LOW CENTERED N OF CENTRAL CUBA
IS FLARING UP A FEW SHOWERS/THUNDERSTORMS OVER THE ISLAND...AS
WELL AS HISPANIOLA. STRONG SHOWERS/THUNDERSTORMS COVER MUCH OF
COSTA RICA AND PANAMA ASSOCIATED WITH DIFFLUENT FLOW ALOFT AND
SURFACE CONVERGENCE AROUND THE E PACIFIC MONSOON TROUGH.
TRADEWIND FLOW OF 15-20 KT IS ACROSS MUCH OF THE BASIN WITH SOME
STRONGER WINDS AROUND THE COAST OF COLOMBIA. EXPECT THE TROPICAL
WAVE TO CONTINUE W OVER THE NEXT COUPLE OF DAYS.
SHOWERS/THUNDERSTORMS ARE POSSIBLE...ESPECIALLY AS IT APPROACHES
THE UPPER LOW OVER CUBA.

ATLANTIC OCEAN...
A LARGE UPPER LEVEL RIDGE COVERS THE NW ATLC CENTERED NEAR
34N65W SUPPORTING A SERIES OF SURFACE HIGH CENTERS FROM N OF THE
AZORES ISLANDS TO THE CENTRAL ATLC NEAR 31N50W TO A WEAK HIGH
CENTER NEAR 27N73W. A SURFACE TROUGH IS IMMEDIATELY E OF THE
WESTERNMOST HIGH CENTER WITH AXIS ALONG 28N68W TO 26N71W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 26N-29N
BETWEEN 69W-74W. A PAIR OF UPPER LEVEL LOWS ARE S OF THIS AREA
CENTERED NEAR 23N78W AND 24N62W. NEITHER LOW IS CAUSING MUCH
ACTIVE WEATHER. HOWEVER...THE SECOND IS ABOVE A SURFACE TROUGH
EXTENDING FROM 26N59W TO 21N63W. THE TROUGH ORIGINATED FROM A
TROPICAL WAVE IN THE EASTERN CARIBBEAN. THE WAVE SPLIT AROUND 24
HOURS AGO AS THE ENERGY TO THE N BEGAN WRAPPING AROUND THE RIDGE
TO THE N. THE TROUGH SHOULD CONTINUE TO MOVE AROUND THE RIDGE.
THE REMAINDER OF THE BASIN IS DOMINATED BY THE 1027 MB HIGH
CENTERED N OF THE AZORES ISLANDS. ALOFT...A BROAD UPPER TROUGH
COVERS THE ERN ATLC. HOWEVER...UPPER LEVEL RIDGING COVERS THE
TROPICAL ATLC. SATELLITE IMAGERY CONTINUES TO SHOW A LARGE AREA
OF SAHARAN DUST ACROSS MUCH OF THE TROPICAL ATLC...WHICH IS
SUPPORTING MOSTLY FAIR CONDITIONS.

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

$$
WALTON





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