[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 140605
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE 14 SEP 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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
0345 UTC.

...SPECIAL FEATURE...
HURRICANE IVAN IS CENTERED NEAR 22.4N 85.6W OR 55 MILES NW OF
THE W TIP OF CUBA AT 14/0600 UTC MOVING NW AT 8 KT. MAXIMUM
SUSTAINED WIND SPEED IS 140 KT WITH GUSTS 170 KT. THIS MAKES
IVAN A DANGEROUS CATEGORY 5 HURRICANE ON THE SAFFIR-SIMPSON
SCALE. MINIMUM CENTRAL PRESSURE IS 922 MB. SEE LATEST NHC PUBLIC
ADVISORY OR NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT4/WTNT34 KNHC OR MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS.
IVAN APPEARS ELONGATED NORTH TO SOUTH WITH NUMEROUS STRONG
CONVECTION ONLY WITHIN 60 NM OF THE CENTER. SCATTERED MODERATE/
STRONG CONVECTION COVERS A LARGER AREA FROM 17N-26N BETWEEN
82W-86W. THE WELL DEFINED EYE MEASURES 24 NM WIDE ON INFRARED
SATELLITE IMAGERY. OUTER RAINBANDS EXTEND OVER S FLORIDA AND THE
FLORIDA KEYS ACROSS WESTERN CUBA BUT ARE LIMITED TO THE W TO
JUST OFFSHORE OF THE YUCATAN PENINSULA. IN THE UPPER
LEVELS...IVAN IS FLANKED BY A SHORTWAVE TROUGH TO THE WEST AND
STRONG MID/UPPER LEVEL RIDGING TO THE EAST. THIS PATTERN
CONTINUES TO SUPPORT EXCELLENT OUTFLOW IN ALL BUT THE W QUADRANT
WHERE SOME WLY FLOW OVER THE CENTRAL GULF IS IMPINGING UPON THE
THE SYSTEM. THIS WLY FLOW IS ASSOCIATED WITH A MID-LATITUDE
TROUGH OVER THE SE UNITED STATES WHICH HAS INCREASE THE WLY
SHEAR OVER IVAN AND IS EXPECTED TO CONTINUE DURING THE NEXT FEW
DAYS. OTHERWISE...THE ATMOSPHERE LOOKS GENERALLY FAVORABLE AND
IVAN SHOULD REMAIN A MAJOR HURRICANE AS IT MOVES ACROSS THE
GULF.

TROPICAL DEPRESSION ELEVEN IS CENTERED NEAR 16.3N 61.8W AT
14/0600 UTC OR NEAR THE NW TIP OF GUADELOUPE MOVING WNW AT 10
KT. MAXIMUM SUSTAINED WIND SPEED IS 25 KT WITH GUSTS TO 35 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010 MB. SEE LATEST NHC
PUBLIC ADVISORY OR NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT1/WTNT31 KNHC OR MIATCMAT1/ WTNT21 KNHC FOR MORE
DETAILS. SATELLITE IMAGERY INDICATES THAT A BROAD CENTER IS OVER
THE LEEWARD ISLANDS NEAR GUADELOUPE. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION CROSSES THE ISLANDS WITHIN 75 NM OF LINE FROM
18N60W SW TO 14N63W. AT THE UPPER LEVELS...THE RIDGING FROM IVAN
IS TO THE IMMEDIATE WEST OF THE T.D. ELEVEN BUT THE ENVIRONMENT
APPEARS FAVORABLE FOR ADDITIONAL DEVELOPMENT OVER THE NEXT FEW
DAYS.

...TROPICAL WAVES...
TROPICAL WAVE IN THE MID ATLC ALONG 41W/42W S OF 27N MOVING W 15
KT. THE WAVE CONTINUES DISPLAY THE CLASSIC SIGNATURE ON
SATELLITE IMAGERY WITH THE ASSOCIATED DEEP CONVECTION TO THE E
OF THE WAVE AXIS. THIS LARGE AMPLITUDE WAY IS ELONGATED WITH NO
ORGANIZED OF THE CONVECTION. CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION COVERS THE AREA WITHIN 150 TO 200 NM
OF LINE FROM 10N39W TO 28N37W.

TROPICAL WAVE IN THE CENTRAL CARIBBEAN ALONG 75W/76W S OF 22N
MOVING W 15 KT. THE WAVE SIGNATURE IS OBSCURED BY HIGH CLOUDS
FROM HURRICANE IVAN. THE CURRENT POSITION IS BASED PRIMARILY
UPON EXTRAPOLATED MOTION. NO ASSOCIATED DEEP CONVECTION.

...ITCZ...
ITCZ AXIS EXTENDS ALONG 17N10W 9N25W 10N40W 8N54W 10N62W.
SCATTERED MODERATE/STRONG CONVECTION IS MOVING OFF THE COAST OF
AFRICA COVERING THE AREA FROM 8N-15N E OF 20W TO INLAND OVER
AFRICA. CLUSTERS OF SCATTERED MODERATE CONVECTION ARE FROM
3N-10N BETWEEN 15W-32W.

...DISCUSSION...

GULF OF MEXICO...
TROUGH CONTINUES TO MOVE SLOWLY TO OVER THE E UNITED STATES WITH
A WELL DEFINED UPPER LEVEL LOW OVER KENTUCKY. UPPER LEVEL
DYNAMICS/LIFT ASSOCIATED WITH THE UPPER TROUGH IS SUPPORTING AN
AREA OF CLOUDINESS WITH SHOWERS/THUNDERSTORMS OVER THE NE GULF
AND THE FLORIDA PENINSULA. WATER VAPOR IMAGERY SHOWS THAT BASE
OF THE TROUGH AMPLIFIED INTO THE N GULF WITH ASSOCIATED
SUBSIDENCE AND DRY AIR NOW AFFECTING THE N GULF COAST FROM THE
FLORIDA PANHANDLE WESTWARD TO TEXAS. A SHORTWAVE TROUGH EXTENDS
S OVER THE CENTRAL GULF AHEAD OF HURRICANE IVAN.
ELSEWHERE...MODERATE SUBSIDENCE AND DRY AIR AHEAD OF HURRICANE
IVAN PREVAILS OVER THE W GULF CREATING A TEMPORARY PERIOD OF
TRANQUIL CONDITIONS.

CARIBBEAN...
IVAN HAS BEGUN TO MORE N OUT OF THE CARIBBEAN INTO THE GULF
MEXICO BUT BROAD RIDGING STILL COVERS THE W TWO-THIRDS OF THE
CARIBBEAN. OUTER RAINBANDS ASSOCIATED WITH IVAN CONTINUE TO
AFFECT MUCH OF CUBA WITH HEAVY RAINS AND GUSTY WINDS MAINLY W OF
80W. TO THE E...T.D. ELEVEN IS OVER THE LEEWARD ISLANDS. SEE
SPECIAL FEATURES ABOVE.

SUBTROPICAL ATLANTIC...
THE TROUGH-RIDGE-TROUGH-RIDGE PATTERN CONTINUES ACROSS THE
SUBTROPICAL ATLC. THE PATTERN IS COMPRISED OF A MID/UPPER LEVEL
LOW 250 NM NE OF BERMUDA WITH A TRAILING TROUGH EXTENDING S TO
20N65W. ASSOCIATED SUBSIDENCE AND DRY AIR COVERS THE AREA N OF
21N FROM 65W-72W LIMITING SIGNIFICANT CLOUDS/CONVECTION SAVE
SOME UPPER LEVEL HIGH CLOUDINESS FROM IVAN OVER THE BAHAMAS. E
OF THE MID/UPPER LOW/TROUGH...DIFFLUENT FLOW IN THE MID-UPPER
LEVELS IS PRODUCING A LARGE AREA OF CLOUDINESS AND SCATTERED
SHOWERS/THUNDERSTORMS WITHIN 150 NM OF LINE FROM 22N63W TO
BEYOND 32N56W. A MID-UPPER LEVEL RIDGE EXISTS OVER THE CENTRAL
ATLC ALONG 54W/55W AND A TROUGH TO THE E EXTENDING FROM A UPPER
LOW NEAR 30N41W S INTO THE TROPICAL ATLC 15N45W. DIFFLUENT FLOW
IN THE MID-UPPER LEVELS AND THE CLOSE PROXIMITY OF THE MID-ATLC
TROPICAL WAVE ARE PRODUCING A LARGE AREA OF CLOUDINESS AND
SCATTERED SHOWERS/THUNDERSTORMS. SEE TROPICAL WAVES ABOVE.
MID/UPPER LEVEL RIDGE IN THE E ATLC EXTENDS ALONG 29W N OF 20N.

TROPICAL ATLANTIC...
A WELL DEFINED MID/UPPER LEVEL RIDGE AXIS EXTENDS WEST FROM OVER
AFRICA ALONG 12N TO 15N35W. THE RIDGE HAS BEEN SLOWLY BUILDING
WESTWARD ALLOWING DEEP LAYERED ELY FLOW TO RETURN TO THE E ATLC.
THIS IS GENERALLY A FAVORABLE REGIME FROM TROPICAL WAVE
DEVELOPMENT. CENTRAL ATLC TROUGH DIPS INTO THE TROPICAL ATLC
WATERS BETWEEN 50W-60W. THIS PATTERN IS PRODUCING ENHANCED ITCZ
CONVECTION FROM 35-45W AND SUPPRESSING ITCZ ACTIVITY BETWEEN
45W-55W.

$$
WALLACE


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