[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181035
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE SEP 18 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 21W S OF 16N MOVING W NEAR 10 KT. AT 850
MB...THERE IS A BROAD CYCLONIC CIRCULATION AND A VORTICITY
MAXIMUM SE OF THE CAPE VERDE ISLANDS NEAR 10N21W. CONVECTION HAS
INCREASED AHEAD OF THE WAVE AXIS. CLUSTERS OF SCATTRED MODERATE
TO ISOLATED STRONG CONVECTION ARE FROM 7N-12N BETWEEN 25W-28W.
SCATTERED MODERATE CONVECTION IS ALSO WITHIN THE ITCZ.

TROPICAL WAVE IS ALONG 47W S OF 19N MOVING WEST NEAR 10-15 KT.
AN INVERTED-V LOW LEVEL SIGNATURE IS WELL DEFINED IN THE NIGHT
CHANNEL SAT IMAGERY. A WEAK 1011 MB LOW IS ALONG THE WAVE AXIS
NEAR 13N. THE WAVE IS ASSOCIATED WITH A LARGE BUT DISORGANIZED
AREA OF SHOWERS AND SCATTERED TSTMS...AND ANY DEVELOPMENT OF
THIS SYSTEM IS EXPECTED TO BE SLOW TO OCCUR AS IT CONTINUES
WESTWARD.

TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 79W S OF 20W
MOVING W 10-15 KT. SHOWER ACTIVITY IS LIMITED IN ASSOCIATION
WITH THIS WAVE.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 9N16W 6N30W 13N46W 11N50W 9N62W.
OUTSIDE OF THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-7N
BETWEEN 21W-29W.

DISCUSSION...

GULF OF MEXICO...
AN UPPER LOW IS INLAND OVER MEXICO NEAR TAMPICO AND COVERS THE
THE FAR WEST GULF. AN UPPER RIDGE EXTENDS FROM THE YUCATAN
PENINSULA NW TO THE LOUISIANA/TEXAS BORDER. A DEEP LAYERED UPPER
TROUGH IS OVER THE EASTERN SEABOARD DIGGING INTO THE E GULF AND
THE STATE OF FLORIDA WITH A POSSIBLE LOW CLOSING OFF THE COAST
OF FLORIDA PENINSULA. LATEST WV IMAGERY IS ALREADY SHOWING THE
UPPER LOW FORMING OFF THE CENTRAL FLA COAST. THERE IS SOME
SHOWERS NEAR THE BASE OF THE TROUGH OVER THE SE GULF. WIDELY
SCATTERED SHOWERS ARE ALSO SEEN OVER THE WESTERN GULF. AT THE
SURFACE...HIGH PRES DOMINATES THE EASTERN US AND THE GULF
PRODUCING LIGHT TO MODERATE NELY WINDS N OF 25N. SOME OF THE
COMPUTER MODELS ARE SUGGESTING A SFC LOW WILL DEVELOP IN THE ERN
GULF WED NIGHT AND THU. THE PRECURSOR OF THIS LOW COULD BE THE
SFC TROUGH THAT IS CURRENTLY E OF FLORIDA. THE GFS MODEL MOVES
THIS TROUGH WWD INTO THE GULF DURING THIS TIME FRAME.

CARIBBEAN SEA...
A RIDGE/TROUGH/RIDGE PATTERN IS OBSERVED ACROSS THE CARIBBEAN
SEA. AN UPPER HIGH OVER THE YUCATAN PENINSULA EXTENDS A RIDGE
OVER THE NW CARIBBEAN AND NORTHERN CENTRAL AMERICA. AN UPPER
TROUGH EXTENDS THROUGH THE WINDWARD PASSAGE INTO THE BASIN TO
CENTRAL AMERICA NEAR THE PANAMA/COAST RICA BORDER. ANOTHER RIDGE
ANCHORED ON A HIGH OVER NORTHERN VENEZUELA DOMINATES THE
REMAINDER OF THE REGION. ABUNDANT MID/UPPER LEVEL MOISTURE IS
BEING ADVECTED EAST OF THE UPPER TROUGH FROM N SOUTH AMERICA
ACROSS THE CENTRAL CARIBBEAN INTO THE ATLC THROUGH HISPANIOLA
AND PUERTO RICO. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN
INTERACTING WITH THIS UPPER LOW/TROUGH. LATEST SATELLITE IMAGERY
ONLY SHOWS WIDELY SCATTERED SHOWERS OVER THE AREA. THE REMNANTS
OF TROPICAL DEPRESSION INGRID ARE LOCATED JUST NORTHEAST OF THE
NORTHERNMOST LEEWARD ISLANDS. A 1010 MB SFC LOW IS ANALYZED NEAR
18.5N62W. A CLUSTER OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION HAS DEVELOPED NE OF THE LOW THANKS TO A DIFFLUENT
PATTERN ALOFT AND THE PRESENCE OF A SFC TROUGH. THIS SHOWER/TSTM
ACTIVITY COVERS AN AREA FROM 19N-22N BETWEEN 58W-61W. THE
CONVECTIVE ACTIVITY THAT WAS AFFECTING GUADALOUPE AND DOMINICA
HAS DIMINISHED. REDEVELOPMENT IS NOT EXPECTED DURING THE NEXT
COUPLE OF DAYS AS THIS SYSTEM MOVES SLOWLY NORTHWESTWARD. LIGHT
TO MODERATE TRADE WINDS ARE IN PLACE.

ATLANTIC OCEAN...
THE DEEP LAYERED TROUGH ALONG THE EASTERN SEABOARD DIGGING INTO
THE PORTION OF THE GULF AND FLORIDA SUPPORTS A STATIONARY FRONT
THAT ENTERS THE REGION NEAR 32N72W...THEN CONTINUES SW TO
28N80W. A SFC TROUGH IS AHEAD OF THE FRONT AND RUNS FROM 28N75W
TO 24N79W. A LARGE AREA OF DISORGANIZED CLOUDINESS AND
THUNDERSTORMS IS ASSOCIATED WITH THESE FEATURES AND EXTENDS FROM
THE EAST COAST OF FLORIDA EASTWARD FOR A FEW HUNDRED MILES OVER
THE WESTERN ATLANTIC AND THE BAHAMAS. CONDITIONS ARE CURRENTLY
UNFAVORABLE FOR DEVELOPMENT IN THIS AREA...BUT SLOW DEVELOPMENT
IS POSSIBLE IN A COUPLE OF DAYS WHEN THE SYSTEM MOVES WESTWARD
OVER FLORIDA AND INTO THE EASTERN GULF OF MEXICO. LOCALLY HEAVY
RAINFALL IS POSSIBLE OVER PORTIONS OF THE FLORIDA PENINSULA AND
THE BAHAMAS DURING THE NEXT DAY OR TWO. AN UPPER RIDGE EXTENDS
FROM THE SE BAHAMA NE TO BEYOND 32N67W. AN UPPER LOW REMAINS
OVER THE CENTRAL ATLC NEAR 34N53W. AN UPPER TROUGH EXTENDS SW
FROM THIS LOW TO NEAR 24N64W. A SURFACE TROUGH ASSOCIATED WITH
THIS UPPER TROUGH EXTENDS FROM 30N46W ALONG 25N55W TO NEAR THE
SFC LOW...REMNANTS OF INGRID. CLOUDINESS WITH EMBEDDED SHOWERS
ARE WITHIN 180 NM EITHER SIDE OF TROUGH. ANOTHER UPPER LOW IS
NEAR 32N34W. A SURFACE TROUGH...REFLECTION OF THIS UPPER LOW
EXTENDS FROM A 1016 MB SFC LOW LOCATED NEAR 32N39W TO 25N43W.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE ON THE SOUTHERN END
OF THE TROUGH. WLY ZONAL FLOW IS IN CONTROL OF THE REMAINDER OF
THE ATLC FROM 20N-32N. UPPER RIDGING IS OVER THE TROPICAL ATLC.
AT THE SFC...TYPICAL SFC RIDGING IS OVER THE REMAINDER OF THE E
ATLC PRODUCING MODERATE NE TRADES E OF 30W...STRONGEST ALONG THE
NW COAST OF AFRICA WHERE THE PRES GRADIENT TIGHTENS BETWEEN THE
AZORES HIGH AND LOWER PRES OVER AFRICA.

$$
GR




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