[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 271105
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT APR 27 2013

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0945 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF SIERRA LEONE NEAR
8N12W TO 4N20W. THE ITCZ BEGINS NEAR 4N20W AND CONTINUES ALONG
3N30W EQ40W 2S44W. A CLUSTER OF NUMEROUS MODERATE CONVECTION HAS
MOVED OFF THE COAST OF AFRICA AND EXTENDS FROM 3N-8N BETWEEN 11W-
17W. SCATTERED SHOWERS ARE WITHIN 80 NM EITHER SIDE OF THE ITCZ
AXIS.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER LEVEL RIDGING CONTINUES ACROSS THE GULF OF MEXICO
SUPPORTING SURFACE RIDGING N OF 22N EXTENDING FROM A 1029
MB HIGH CENTERED NEAR 37N75W. E TO SE SURFACE WINDS OF 5-20 KT
SPREAD ACROSS THE GULF AND AROUND THE RIDGE ALONG WITH MOSTLY
CLEAR SKIES. A WEAK SURFACE TROUGH IS OVER THE BAY OF CAMPECHE
ALONG 21N92W TO 17N93W. ISOLATED SHOWERS ARE POSSIBLE IN THE BAY
OF CAMPECHE S OF 22N ASSOCIATED TO THE SURFACE TROUGH AND BEING
ENHANCED BY MOISTURE ADVECTION FROM THE E PACIFIC OCEAN. LITTLE
CHANGE IS EXPECTED OVER THE NEXT 24 HOURS AS SURFACE RIDGING
REMAINS THE DOMINANT FEATURE. THE TAIL OF A COLD FRONT IS
EXPECTED TO ENTER THE NW GULF SUNDAY MORNING.

CARIBBEAN SEA...
BROAD UPPER RIDGING ACROSS THE GULF OF MEXICO
EXTENDS TO THE WESTERN CARIBBEAN. SCATTERED SHOWERS ARE POSSIBLE
IN THE YUCATAN CHANNEL AND WITHIN 100 NM FROM THE SOUTHERN
COASTLINE OF CUBA DUE TO MOISTURE ADVECTION FROM THE E PACIFIC
OCEAN BY W-NW FLOW. AN UPPER LEVEL TROUGH CONTINUES POSITIONED
OVER THE REMAINDER OF THE CARIBBEAN. DRY AIR IN THE MIDDLE
LEVELS ASSOCIATED TO THIS TROUGH CONTINUES FAVORING MOSTLY FAIR
CONDITIONS AT THE SURFACE WITH ONLY A FEW PATCHES OF POSSIBLE
ISOLATED SHOWERS WITHIN 150 NM S OF LA HISPANIOLA AS WELL AS
WITHIN 200 NM OF THE HONDURAS COASTLINE. ISOLATED SHOWERS ARE
ALSO IN THE FAR SE CORNER OF THE BASIN. A MUCH LARGER AREA OF
SCATTERED SHOWERS IS EAST OF THE WINDWARD ISLANDS ASSOCIATED
WITH MOIST SOUTHWESTERLY FLOW ALOFT AROUND THE UPPER TROUGH.
THIS AREA OF MOIST CONDITIONS EAST OF THE ISLANDS MAY DRIFT WEST
OVER THE WEEKEND POSSIBLY BRINGING HEAVY RAINFALL TO SOME OF THE
SOUTHERN LESSER ANTILLES. TRADEWIND FLOW OF 10-15 KT DOMINATES
THE CENTRAL AND EASTERN CARIBBEAN WHILE WINDS UP TO 20 KT SPREAD
OVER THE WESTERN AND SOUTHERN REGIONS OF THE BASIN DUE TO A
TIGHTER PRESSURE GRADIENT.

ATLANTIC OCEAN...
A NARROW UPPER LEVEL TROUGH IN THE W ATLC EXTENDS ALONG 66W
SUPPORTING A COLD FRONT N OF THE DISCUSSION AREA THAT
TRANSITIONS TO A SURFACE TROUGH ENTERING THE DISCUSSION AREA
ALONG 30N65W TO 28N66W. CONVECTION ASSOCIATED TO THIS FRONTAL
BOUNDARY IS MOSTLY N OF THE DISCUSSION AREA...HOWEVER SCATTERED
SHOWERS ARE POSSIBLE N OF 28N BETWEEN 62W AND 65W. AN INVERTED
SURFACE TROUGH IS NE OF LA HISPANIOLA ALONG 26N69W 23N70W TO
20N69W. NO CONVECTIVE PRECIPITATION IS ASSOCIATED WITH THIS
TROUGH. FARTHER EAST AN UPPER LEVEL LOW LOCATED NEAR 36N35W IS
SUPPORTING A 1004 MB SURFACE LOW NEAR 34N33W WITH AN ASSOCIATED
COLD FRONT THAT ENTERS THE DISCUSSION AREA ALONG 30N25W 24N31W
TO 22N42W. SCATTERED SHOWERS IN THE VICINITY OF THE COLD FRONT
ARE ASSOCIATED WITH MOIST SOUTHWESTERLY FLOW ALOFT AROUND THE E
SIDE OF THE UPPER TROUGH WITH AXIS OVER THE E CARIBBEAN. THESE
SHOWERS ARE BOUNDED IN AN AREA FROM 19N-27N BETWEEN 20W-47W.

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

$$
NR


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