[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 300543
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU 30 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
0315 UTC.

...SPECIAL FEATURES...
TROPICAL STORM LISA IS CENTERED NEAR 31.5N 46.2W AT 30/0300 UTC
MOVING NNW AT 9 KT. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH
GUSTS TO 75 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER
MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. LISA IS LOCATED IN THE
NE PORTION OF AN MID/UPPER LEVEL LOW PROVIDING NORTHEASTERLY
SHEAR. NO ASSOCIATED DEEP CONVECTION REMAINS WITH SCATTERED
SHOWERS SW OF THE LOW LEVEL CENTER WITHIN 90 NM OF 30N FROM
45W-53W.

...TROPICAL WAVES...
EASTERN MOST TROPICAL WAVE IS ABOUT MIDWAY BETWEEN AFRICA AND
THE WINDWARD ISLANDS ALONG 39W S OF 15N MOVING W 10-15 KT. WEAK
MID LEVEL CIRCULATION IS OBSERVED ON SATELLITE IMAGERY WITH
ASSOCIATED DEEP CONVECTION TO THE E OF THE WAVE AXIS. HOWEVER
WESTERLY SHEAR IS PREVENTING ANY DEVELOPMENT. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 45/60 NM OF 12N
FROM 35W-38W.

WESTERN MOST TROPICAL WAVE IS ABOUT 675 NM W OF BARBADOS ALONG
48W S OF 15N MOVING W 10-15 KT. WEAK LOW LEVEL CURVATURE IS
OBSERVED ON SATELLITE IMAGERY. THIS WAVE IS ON THE SOUTH SIDE OF
AN MID/UPPER LEVEL HIGH WHICH IS FUNNELING IN DRY AIR INTO THE
BACK SIDE OF THE WAVE THUS PREVENTING FURTHER DEVELOPMENT.
CLUSTERS OF SCATTERED MODERATE CONVECTION COVER THE AREA FROM
8N-13N BETWEEN 45W-52W.

TROPICAL WAVE IN THE S GULF OF MEXICO IS ALONG 94W S OF 18N
MOVING W 10 KT. THIS IS A VERY WEAK WAVE WITH NO ASSOCIATED
CONVECTION IN THE ATLANTIC BASIN.

...ITCZ...
ITCZ IS CENTERED ALONG 11N15W 6N33W 9N43W 10N62W. SCATTERED
MODERATE/STRONG CONVECTION IS WITHIN A 75 NM RADIUS OF 12N31.5W.
BROAD AREA WITH CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVER THE REMAINDER OF THE AREA FROM 1N-16N BETWEEN
20W-44W.

...DISCUSSION...
GULF OF MEXICO AND W ATLANTIC...
BROAD DEEP LAYERED TROUGH COVERS THE THE EASTERN TWO-THIRDS OF
THE UNITED STATES EXTENDING S OVER TEXAS AND INTO THE NW GULF.
THE ASSOCIATED COLD FRONT EXTENDS INTO THE GULF OVER THE FLORIDA
PANHANDLE NEAR 30N86W ALONG 25N90W INTO THE BAY OF CAMPECHE AND
S MEXICO NEAR 18N95W CONTINUING NW AS A DISSIPATING STATIONARY
FRONT ALONG THE MOUNTAINS OF MEXICO. STRONG SUBSIDENCE/DRY AIR
AT ALL LEVELS IS PREVENTING ANY SHOWERS W OF THE FRONTAL
BOUNDARY. MID/UPPER LEVEL HIGH IS ALONG THE COAST MEXICO NEAR
19N97W WITH A RIDGE AXIS EXTENDING NE ACROSS S FLORIDA INTO THE
W ATLANTIC TO BEYOND BERMUDA. ANTICYCLONIC FLOW COVERS THE W
ATLC WITHIN 250/300 NM OF THE AXIS AND THE GULF SW OF THE
FRONTAL TROUGH. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
INLAND AND ALONG THE COAST IN THE BAY OF CAMPECHE ALONG THE
YUCATAN PENINSULA FROM 87W-93W AND S MEXICO FROM 94W-96W. AT THE
SURFACE...A WEAK SURFACE TROUGH EXTENDS FROM 23N66W TO 30N61W.
SCATTERED MODERATE CONVECTION IS WITHIN 60 NM OF LINE FROM
25N59W-27N61W.

CARIBBEAN SEA...
ANTICYCLONIC FLOW FROM THE MID/UPPER LEVEL HIGH IN THE SW GULF
CONTINUES OVER THE NW CARIBBEAN N OF 14N W OF 80W. THIS IS
BRINGING IN MODERATE SUBSIDENCE/DRY AIR OVER THE AREA THUS
LIMITING ISOLATED SHOWER ACTIVITY TO THE LOW LEVELS IN THIS
AREA. BROAD MID/UPPER LEVEL LOW IS CENTERED NEAR 16N71W WITH
CYCLONIC FLOW WITHIN 250/300 NM OF AN AXIS FROM THE SW ATLC N OF
PUERTO RICO NEAR 22N66W SW TO 13N79W. THIS IS PRODUCING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 15N FROM 60W TO
80W INCLUDING THE LEEWARD/VIRGIN ISLANDS...PUERTO RICO...
HISPANIOLA...AND JAMAICA. THIS UPPER LOW IS ALSO ADVECTING THE
MOISTURE EASTWARD OVER COLOMBIA AND NW VENEZUELA WHICH IS
PRODUCING SCATTERED STRONG CONVECTION S OF 13N FROM 67W-74W
INCLUDING LAKE MARACAIBO. THE DIFFLUENCE BETWEEN THE RIDGE TO
THE NW AND THE LOW TO THE E IS PRODUCING OVERCAST MULTILAYERED
CLOUDS WITH CLUSTERS OF SHOWERS/THUNDERSTORMS ACROSS THE S
CARIBBEAN S OF 14N FROM 74W-84W.

CENTRAL/EASTERN ATLANTIC...
MID/UPPER LEVEL LOW IN THE CENTRAL ATLC IS CENTERED SW OF T.S.
LISA NEAR 27N52W WITH A TROUGH AXIS EXTENDING FROM 34N47W S TO
21N57W. CYCLONIC FLOW IS WITHIN 250/300 NM OF THE AXIS. LISA IS
EMBEDDED WITHIN THE FLOW SURROUNDED BY STRONG SUBSIDENCE AND THE
POSITION OF LISA IS SEVERELY LIMITING ANY CONVECTION WITH THE
STROM. SCATTERED MODERATE CONVECTION IS ON THE SE SIDE OF THE
LOW WITHIN 60 NM OF LINE FROM 21N54W-23N49W. MID/UPPER LEVEL LOW
OVER THE SE ATLC IS CENTERED NEAR 21N35W WITH CYCLONIC FLOW S OF
25 FROM 27W-39W. AN INDUCED MID/UPPER LEVEL HIGH IS BETWEEN THE
LOWS NEAR 27N38W.

TROPICAL ATLANTIC...
MID/UPPER HIGH IS NEAR 15N48W WITH ANTICYCLONIC MODERATE
SUBSIDENCE S OF 20N FROM 40W-57W. THE MID/UPPER LOW FROM THE SE
ATLC NEAR 21N35W HAS CYCLONIC FLOW N OF 12N FROM 27N-39W. THIS
FEATURE IS ENHANCING THE ACTIVITY WITHIN THE ITCZ. A MID/UPPER
LEVEL HIGH IS OFF THE SW COAST OF AFRICA NEAR 12N20W WITH
ANTICYCLONIC FLOW S OF 23N E OF 25W.

$$
WALLACE


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