[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 141803
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE OCT 14 2008

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURES...

TROPICAL DEPRESSION FIFTEEN IN THE EASTERN CARIBBEAN SEA
STRENGTHENS INTO TROPICAL STORM OMAR. AT 14/1800 UTC OMAR IS
CENTERED NEAR 13.8N 68.9W OR ABOUT 325NM...600 KM...SOUTH-
SOUTHWEST OF SAN JUAN PUERTO RICO AND ABOUT 95 NM...180 KM...
NORTH OF CURACAO MOVING SE AT 4 KT. A GRADUAL TURN TO THE EAST
IS FORECAST TO OCCUR LATER TODAY...WITH A GRADUAL INCREASE IN
FORWARD SPEED AND A TURN TO THE NORTHEAST EXPECTED ON WEDNESDAY.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB. MAXIMUM SUSTAINED
WIND SPEED HAS INCREASED TO 35 KT WITH GUSTS TO 40 KT. GRADUAL
STRENGTHENING IS FORECAST OVER THE NEXT 48 HOURS...WITH OMAR
REACHING HURRICANE STATUS. PLEASE SEE LATEST NHC PUBLIC ADVISORY
UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35 KNHC AND THE FULL
FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC
FOR MORE DETAILS. RECENT DEVELOPMENT OF A CDO-LIKE AREA OF
CENTRAL DEEP CONVECTION SUGGESTS THAT OMAR MAY BE STARTING A
PERIOD OF RAPID STRENGTHENING. BANDS OF MODERATE TO STRONG
CONVECTION ARE SEEN TO THE N AND SE OF OMAR'S CENTER. CLUSTERS
OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE AFFECTING
THE ABC ISLANDS. THIS MORNING CURACAO REPORTED 1.70 INCHES OF
RAIN IN 24 HOURS. GUSTY WINDS AND HEAVY RAIN WILL CONTINUE TO
AFFECT ARUBA...BONAIRE AND CURACAO THE REST OF TODAY.

SATELLITE AND SURFACE OBSERVATIONS INDICATE THAT THE AREA OF LOW
PRESSURE OVER THE WESTERN CARIBBEAN SEA HAS ACQUIRED ENOUGH
ORGANIZATION TO BE DESIGNATED A TROPICAL DEPRESSION. AT 14/1800
UTC...T.D. SIXTEEN IS CENTERED NEAR 15.6N AND 83.2W OR ABOUT 35
NM...65 KM...NORTH-NORTHEAST OF CABO GRACIAS A DIOS ON THE
NICARAGUA/HONDURAS BORDER MOVING W-NW AT 4 KT. A TURN TOWARD THE
WEST IS EXPECTED LATER TODAY AND A GENERAL WESTWARD MOTION IS
FORECAST WEDNESDAY AND WEDNESDAY NIGHT. ESTIMATED MINIMUM
CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 25
KT WITH GUSTS TO 35 KT. AN AIR FORCE RESERVE RECONNAISSANCE
AIRCRAFT IS SCHEDULED TO INVESTIGATE THE DEPRESSION THIS
AFTERNOON. SOME STRENGTHENING IS EXPECTED DURING THE NEXT COUPLE
OF DAYS AS LONG AS THE CENTER OF DEPRESSION REMAINS
OFFSHORE...AND THE DEPRESSION IS FORECAST TO BECOME A TROPICAL
STORM BY WEDNESDAY. PLEASE SEE LATEST NHC PUBLIC ADVISORY UNDER
AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC AND THE FULL FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21 KNHC FOR MORE
DETAILS. BANDING FEATURES WITH MODERATE TO ISOLATED STRONG
CONVECTION ARE OBSERVED WITHIN 240 NM NW QUADRANT AND WITHIN 200
NM E SEMICIRCLE.

...TROPICAL WAVES...

A TROPICAL WAVE IS ADDED TO THE 1200 UTC SURFACE MAP ALONG 33W
SOUTH OF 13W BASED ON SATELLITE PHOTOS AND SURFACE OBSERVATIONS.
IN ADDITION...THE HOVMOLLER DIAGRAM SHOWS VERY CLEAR THE WWD
PROPAGATION OF THE CLOUDINESS AND THE TPW PRODUCT FROM CIMSS
INDICATES A BULGE OF MOISTURE ALONG THE WAVE AXIS. SCATTERED
MODERATE CONVECTION IS SEEN EITHER SIDE OF THE WAVE AXIS
COVERING A LARGE AREA FROM 5N-13N BETWEEN 28W-38W.

A WEAK TROPICAL WAVE IS ALONG 53W/54W S OF 17N MOVING W NEAR 10
KT. THE WAVE IS EMBEDDED IN AN AREA OF MODERATE TO STRONG
SUBSIDENCE KEEPING ANY ASSOCIATED SHOWERS CONFINED TO THE ITCZ
NEAR 11N54W. THE WAVE SHOWS UP ON THE SSMI-TPW PRODUCT FROM
CIMSS...AND VIS SATELLITE IMAGERY DEPICTS A WEAK INVERTED
V-SIGNATURE ASSOCIATED WITH THIS FEATURE.

A TROPICAL WAVE IS OVER THE LESSER ANTILLES ALONG 61W/62W SOUTH
OF 18N MOVING WEST NEAR 10 KT. THE WAVE IS GENERATING SOME
SHOWER/TSTM ACTIVITY BETWEEN MARTINIQUE AND BARBADOS. GUADELOUPE
REPORTED 1.17 INCHES OF RAIN THIS MORNING FOR THE PAST 24 HOURS.
THIS WAVE IS EXPECTED TO BECOME ABSORBED INTO T.S. OMAR PRETTY
SOON AS IT TRACKS WESTWARD.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N16W 9N30W 8N40W 9N50W 10N60W. A
1008 MB LOW IS EMBEDDED WITHIN THE ITCZ NEAR 13N42W. IN ADDITION
TO CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS INLAND OVER WEST AFRICA
FROM 9N-15N BETWEEN 10W-17W. SCATTERED MODERATE CONVECTION IS
WITHIN 150 NM N OF AXIS BETWEEN 24W-30W.

...DISCUSSION...

GULF OF MEXICO...
THE UPPER-LEVEL LOW THAT WAS CENTERED OVER THE BAY OF CAMPECHE
YESTERDAY NIGHT HAS CONTINUED TO MOVE WWD AND NOW IS ROTATING
OVER MEXICO NEAR 19N98W. LOW-LEVEL INSTABILITY AND MOIST
SOUTHERLY MID-HIGH LEVEL FLOW TO THE EAST OF THIS FEATURE IS
HELPING TO INDUCE SCATTERED SHOWERS AND TSTMS OVER THE WESTERN
GULF PARTICULARLY FROM 23N-27N WEST OF 90W. A SFC TROUGH...
LIKELY A REFLECTION OF THE UPPER FEATURE IS ANALYZED ALONG 93W
SOUTH OF 26N. A QSCAT PASS FROM AROUND 1230 UTC SHOWED THE WIND
SHIFT ASSOCIATED WITH THIS SFC TROUGH. A HIGH PRESSURE CENTER
OVER THE MID-ATLANTIC STATES DOMINATES THE SE CONUS...THE
FLORIDA PENINSULA AND THE NORTHERN GULF WATERS. THE PRESSURE
GRADIENT BETWEEN THIS HIGH AND T.D. SIXTEEN ACROSS THE WRN
CARIBBEAN SEA IS GENERATING MODERATE TO STRONG ELY WINDS OVER
THE MIDDLE AND ERN GULF.

CARIBBEAN SEA...
A TROPICAL WAVE AND TWO TROPICAL CYCLONES ARE IN THE CARIBBEAN
SEA...ONE IS T.S. OMAR IN THE ERN CARIBBEAN...AND THE SECOND ONE
IS T.D. SIXTEEN IN THE WRN CARIBBEAN...SEE SPECIAL FEATURES FOR
MORE DETAILS. UPPER-LEVEL RIDGE IS OVER T.D. SIXTEEN COVERING
MUCH OF THE BASIN WHICH IS AIDING IN GENERATING THE CONVECTIVE
ACTIVITY ASSOCIATED WITH BOTH TROPICAL SYSTEMS. WV IMAGERY
REVEALS A DEEP LAYER TROUGH DIGGING INTO THE WEST AND CENTRAL
ATLC. THIS TROUGH WILL PLAY A ROLE IN THE FUTURE MOVEMENT OF
OMAR...WHICH IS FORECAST TO BE EMBEDDED IN THE ELY FLOW AHEAD OF
THIS TROUGH. AS A RESULT...OMAR IS EXPECTED TO MOVE TO THE EAST
DURING THE NEXT 12 HOURS. HIGH CLOUDS ASSOCIATED WITH THE
OUTFLOW OF T.D. SIXTEEN ARE REACHING CUBA. SCATTERED TO
NUMEROUS SHOWERS WITH EMBEDDED TSTMS ARE AFFECTING THE VIRGIN
ISLANDS AND NE PUERTO RICO WHILE AN OUTER RAINBAND ASSOCIATED
WITH T.S. OMAR IS SLOWLY APPROACHING THE SOUTH COAST OF PUERTO
RICO. ST.THOMAS REPORTED THIS MORNING 3.85 INCHES OF RAIN IN 24
HOURS.

ATLANTIC OCEAN...
THE LAST PUBLIC ADVISORY ON T.D. NANA WAS ISSUED BY THE NATIONAL
HURRICANE CENTER AT 14/0900 UTC. SLOW WEAKENING OF THE SYSTEM IS
FORECAST UNTIL THE REMNANT LOW OF NANA DISSIPATES IN A COUPLE OF
DAYS. AT 14/1500 UTC...THE EXPOSED LOW LEVEL CENTER OF WHAT WAS
NANA IS NEAR 18.5N44.5W. ANOTHER EXPOSED LOW LEVEL CENTER IS TO
THE SE OF NANA'S REMNANT NEAR 16.5N41.5N. THIS LOW CONTINUES TO
PRODUCE SOME THUNDERSTORM ACTIVITY MAINLY TO THE EAST OF THE
CENTER...BUT THIS SYSTEM IS FORECAST TO ENCOUNTER UNFAVORABLE
UPPER-LEVEL WINDS AS IT MOVES SLOWLY NORTH-NORTHEASTWARD OVER
THE NEXT DAY OR TWO...AND SIGNIFICANT DEVELOPMENT IS NOT
ANTICIPATED. A SURFACE TROUGH...ASSOCIATED WITH BROAD UPPER
TROUGHING ACROSS THE W-CENTRAL ATLC...EXTENDS INTO THE
DISCUSSION AREA NEAR 31N47W TO 20N66W. A LARGE AREA OF
CLOUDINESS WITH EMBEDDED SHOWERS IS MAINLY AHEAD OF THE TROUGH
AXIS FROM 20N-27N BETWEEN 50W-62W. ANOTHER SURFACE TROUGH CLIPS
THE REGION NEAR 31N63W. THE E ATLC IS UNDER THE INFLUENCE OF A
SFC RIDGE ANCHORED ON A 1026 MB HIGH CENTERED EAST OF THE AZORES
NEAR 35N22W. SURFACE OBSERVATIONS ALSO SHOW THE PRESENCE OF A
1011 MB LOW INLAND OVER WEST AFRICA NEAR 14N15W. A BROAD
UPPER-LEVEL RIDGE ANCHORED ON AN HIGH NEAR 11N28W DOMINATES THE
TROPICS AND IS ENHANCING CONVECTION ALONG THE ITCZ.

$$
GR





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