Tropical Weather Discussion
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000
AXNT20 KNHC 250002
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN AUG 24 2014

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
2345 UTC.

...SPECIAL FEATURES...

TROPICAL STORM CRISTOBAL IS CENTERED NEAR 24.5N 73.0W AT 24/2100
UTC OR ABOUT 135 NM E-NE OF LONG ISLAND OR ABOUT 160 NM E-NE OF
GREAT EXUMA ISLAND IN THE BAHAMAS. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 1001 MB. MAXIMUM SUSTAINED WINDS ARE 40 KT WITH
GUSTS TO 50 KT. ON THE FORECAST TRACK...THE CENTER OF CRISTOBAL
WILL PASS NEAR OR TO THE EAST OF THE CENTRAL BAHAMAS THROUGH
MONDAY. SOME GRADUAL STRENGTHENING IS FORECAST DURING THE NEXT
48 HOURS. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE
FROM 16N-27N BETWEEN 68W-78W...INCLUDING
HISPANIOLA...JAMAICA...EASTERN CUBA AND ADJACENT WATERS.
CRISTOBAL IS EXPECTED TO PRODUCE RAINFALL TOTALS OF 4 TO 8
INCHES OVER THE TURKS AND CAICOS ISLANDS...AS WELL AS THE
SOUTHEASTERN AND CENTRAL BAHAMAS THROUGH TUESDAY...WITH ISOLATED
AMOUNTS AROUND 12 INCHES POSSIBLE. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS.

...TROPICAL WAVES...

A TROPICAL WAVE IS EAST OF THE CAPE VERDE ISLANDS WITH AXIS
EXTENDING FROM 18N21W TO 12N22W. THE WAVE IS EMBEDDED IN THE
MONSOON TROUGH AND IS ASSOCIATED WITH MODERATE MOISTURE AT THE
LOWER AND MIDDLE LEVELS. HOWEVER...DRY SAHARAN AIR AND DUST ARE
OBSERVED IN THE WAVE ENVIRONMENT WHICH ALONG STRONG DEEP LAYER
ENVIRONMENTAL SHEAR INHIBIT DEEP CONVECTION. ISOLATED SHOWERS
ARE SE OF THE WAVE AXIS.

A TROPICAL WAVE IS ON THE CENTRAL ATLC WITH AXIS EXTENDING FROM
17N33W TO A 1010 MB LOW NEAR 11N33W...MOVING W AT 20 KT. THE
WAVE IS EMBEDDED IN THE MONSOON TROUGH AND DEEP LAYER HIGH MOIST
ENVIRONMENT IS ASSOCIATED WITH IT S OF 13N WHERE SCATTERED
MODERATE CONVECTION IS NOTED FROM 9N-13N BETWEEN 31W-36W.
SAHARAN DRY AIR AND DUST ENGULFS THE NORTHERN PORTION OF THE
IT...THUS HINDERING CONVECTION.

A LOW AMPLITUDE TROPICAL WAVE IS FARTHER WEST WITH AXIS EXTENDING
FROM 14N45W TO 9N45W...MOVING W AT 20 KT. THE WAVE IS DEVOID OF
CONVECTION AS SAHARAN DRY AIR AND DUST IS IN ITS ENVIRONMENT.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC
NEAR 19N16W AND THEN CONTINUES ALONG 14N22W TO A 1010 MB LOW
NEAR 11N33W TO 8N37W. THE ITCZ BEGINS NEAR 8N37W AND CONTINUES
TO 6N47W 8N54W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...A CLUSTER OF MODERATE CONVECTION IS FROM 8N-12N BETWEEN
38W-41W.

...DISCUSSION...

GULF OF MEXICO...

A MIDDLE TO UPPER LEVEL TROUGH IS ON THE WESTERN ATLC SUPPORTING
A FRONTAL SYSTEM ANALYZED AS A BACKDOOR COLD FRONT ALONG THE
NORTHERN FLORIDA PENINSULA. THIS FRONT ALONG A DIFFLUENT
ENVIRONMENT ALOFT BEING GENERATED BY AN UPPER LEVEL INVERTED
TROUGH COVERING MOST OF THE GULF SUPPORT SCATTERED HEAVY SHOWERS
AND TSTMS ALONG THE WESTERN FLORIDA PENINSULA N OF 25N. SIMILAR
CONVECTION IS NOTED ON THE EASTERN GULF FROM 23N-28N BETWEEN 84W-
89W. WEAK SURFACE RIDGING IS OVER THE WESTERN GULF PROVIDING
ANTICYCLONIC WIND FLOW OF 5-10 KT. NORTHERLY FLOW OF THE SAME
MAGNITUDE IS ON THE REMAINDER BASIN. MOISTURE ASSOCIATED WITH
THE FRONTAL SYSTEM WILL CONTINUE TO SUPPORT RAINSHOWERS AND
POSSIBLE TSTMS ACROSS THE FLORIDA PENINSULA THROUGH TUESDAY
MORNING AND ACROSS THE NORTHERN AND EASTERN GULF BEYOND TUESDAY
NIGHT. SURFACE RIDGING WILL DOMINATE ACROSS THE WESTERN GULF
THROUGH WED NIGHT.

CARIBBEAN SEA...

A BROAD UPPER-LEVEL ANTICYCLONE DOMINATES THE WESTERN AND
CENTRAL CARIBBEAN WHILE AN INVERTED UPPER TROUGH IS ON THE EAST
OF THE BASIN. SOUTHERLY LOW-LEVEL WIND FLOW FEEDING T.S.
CRISTOBAL ON THE SW N ATLC IS ENHANCING SCATTERED HEAVY SHOWERS
ACROSS CENTRAL AND WESTERN HISPANIOLA...THE WINDWARD PASSAGE AND
EASTERN CUBA. THIS SHOWER ACTIVITY EXTENDS TO 15N TO INCLUDE
JAMAICA AND COASTAL WATERS OF THE ABOVE-MENTIONED TERRITORIES.
SCATTEROMETER DATA DEPICTED A SURFACE TROUGH EXTENDING FROM
EASTERN CUBA NEAR 20N75W SW TO 14N82W. THIS TROUGH IS ENHANCING
ISOLATED SHOWERS ON THE NW CARIBBEAN BETWEEN 77W-85W. A
DIFFLUENT ENVIRONMENT ALOFT BETWEEN THE RIDGE AND THE INVERTED
TROUGH COULD SUPPORT ISOLATED SHOWERS AND THUNDERSTORMS ON
PUERTO RICO. THE REMAINDER OF THE CARIBBEAN IS UNDER FAIR
CONDITIONS TONIGHT. SHOWERS ASSOCIATED WITH CRISTOBAL WILL
CONTINUE TO AFFECT HISPANIOLA AND CUBA THROUGH TUESDAY MORNING.
THE NEXT TROPICAL WAVE WILL ENTER THE EASTERN CARIBBEAN WED
MORNING.

...HISPANIOLA...

MOIST LOW-LEVEL SOUTHERLY WIND FLOW FEEDING T.S. CRISTOBAL IS
SUPPORTING SCATTERED HEAVY SHOWERS/ISOLATED THUNDERSTORMS OVER
THE CENTRAL AND WESTERN ISLAND. RAINSHOWERS ARE FORECAST TO
CONTINUE THROUGH TUE MORNING. ONAMET HAS ISSUED WEATHER ALERTS
FOR FLASH FLOODS AND LANDSLIDES OVER PORTIONS  OF THE ISLAND.
PLEASE SEE ONAMET WEBSITE AT WWW.ONAMET.GOV.DO FOR MORE
INFORMATION.

ATLANTIC OCEAN...

THE MAIN FEATURE ON THE BASIN IS T.S. CRISTOBAL JUST N OF THE
SOUTHERN BAHAMAS ISLANDS. SEE SPECIAL FEATURES ABOVE. A BROAD
UPPER TROUGH COVERS THE NW ATLC N OF 28N SUPPORTING A COLD FRONT
ANALYZED ALONG 30N77W SW TO THE NE FLORIDA COASTLINE NEAR
29N81W. LOW-LEVEL MOISTURE CONVERGENCE ALONG WITH AN UPPER
DIFFLUENT ENVIRONMENT ALOFT SUPPORT SCATTERED MODERATE
CONVECTION AND ISOLATED TSTMS AHEAD OF THE FRONT N OF 25N
BETWEEN 64W-71W. THE REMAINDER OF THE ATLC BASIN IS DOMINATED BY
A SURFACE RIDGE ANCHORED BY A 1024 MB HIGH NEAR 33N29W. SHOWERS
ARE EXPECTED ACROSS THE SW N ATLC BEYOND WED MORNING.

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

$$
NR



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