[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 290524
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON SEP 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0500 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS MOVING ACROSS THE CAPE VERDE ISLANDS ALONG
24W SOUTH OF 17N. THE WAVE IS MOVING WESTWARD NEAR 10 KT. THE
SSMI-DERIVED TPW INDICATES A MOISTURE MAXIMUM JUST OVER THE CAPE
VERDE ISLANDS. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN
150 NM WEST OF THE AXIS FROM 12N-15N.

A TROPICAL WAVE IS ALONG 41W SOUTH OF 19N MOVING WEST 10 TO 15
KT. BROAD LOW LEVEL CIRCULATION IS VISIBLE ON SATELLITE IMAGERY
NEAR 15N. CLUSTERS OF MODERATE CONVECTION IS BEHIND THE AXIS TO
35W NORTH OF 15N. SCATTERED MODERATE CONVECTION IS ALONG THE
AXIS BETWEEN 39W-42W FROM 7N-10N.

A TROPICAL WAVE IS ALONG 53W SOUTH OF 17N MOVING WEST NEAR 10
KT. AN UPPER-LEVEL LOW SPINNING EAST OF THE LESSER ANTILLES IS
PRODUCING MODERATE TO STRONG UPPER-LEVEL SWLY FLOW OVER THE
WAVE. NO SIGNIFICANT CONVECTION IS ASSOCIATED WITH THIS WAVE.

A TROPICAL WAVE IS OVER NICARAGUA ALONG 84W SOUTH OF 16N MOVING
WEST 10 TO 15 KT. CONVECTION ASSOCIATED WITH THIS WAVE IS NOW
OVER THE EASTERN PACIFIC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 10N13W 8N25W 8N35W 9N45W AN INTO
SOUTH AMERICA NEAR 9N61W. IN ADDITION TO CONVECTION ASSOCIATED
WITH TROPICAL WAVES...A LARGE CLUSTER OF MODERATE TO STRONG
CONVECTION IS MOVING OFF THE WEST COAST OF AFRICA AND EXTENDS TO
20W FROM 11N-14N. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM
SOUTH OF THE AXIS BETWEEN 33W-37W.

...DISCUSSION...

THE GULF OF MEXICO...
A BROAD LOW PRESSURE SYSTEM OVER THE YUCATAN PENINSULA IS
GENERATING NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE SE GULF.
AS OF 0300 UTC...THE 1010 MB LOW WAS ANALYZED NEAR 21N90W. A
SURFACE TROUGH EXTENDS FROM THE LOW CENTER NORTHWARD TO NEAR
22N90W THEN NORTHEASTWARD ALONG 25N85W...CROSSING THE FLORIDA
PENINSULA NEAR TAMPA BAY. CONVECTIVE ACTIVITY EXTENDS UP TO 200
NM SE OF THE TROUGH COVERING THE YUCATAN CHANNEL...WESTERN
CUBA...FLORIDA STRAIGHTS...AND SOUTH FLORIDA INTO THE W ATLC.
THE LOW IS FORECAST TO EMERGE INTO THE SOUTH-CENTRAL GULF OF
MEXICO AND MOVE RAPIDLY NE...REACHING THE FLORIDA PENINSULA NEAR
TAMPA BAY EARLY TUE. E TO SE WINDS OF 10-15 KT ARE OBSERVED IN
THIS REGION. PRES GRADIENT BETWEEN THIS LOW PRESSURE AREA AND
HIGHER PRESSURE OVER THE WESTERN GULF IS PRODUCING NLY WINDS OF
15-20 KT OVER THE SW PORTION OF THE GULF INCLUDING THE BAY OF
CAMPECHE. NE WINDS 10-15 KT COVER THE REMAINDER OF THE GULF.
ALOFT...A MID/UPPER LEVEL TROUGH LIES OVER THE WESTERN HALF OF
THE GULF WITH ITS AXIS ALONG 94W. UPPER-LEVEL SWLY WINDS AHEAD
OF THIS TROUGH ARE LIMITING THE DEVELOPMENT OF THE
AFOREMENTIONED SFC LOW.

THE CARIBBEAN SEA...
SCATTERED SHOWERS AND THUNDERSTORMS IN THE EXTREME NW CARIBBEAN
ARE ASSOCIATED WITH A 1010 MB SURFACE LOW OF THE YUCATAN
PENINSULA. UPPER LEVEL DIFFLUENCE ALONG THE SOUTHERN PERIPHERY
OF AN UPPER HIGH NE OF THE BAHAMAS IS GENERATING A LARGE
CLUSTER OF MODERATE TO STRONG CONVECTION OVER THE WINDWARD
PASSAGE BETWEEN HAITI AND CUBA. A SHORTWAVE TROUGH OVER THE
CENTRAL CARIBBEAN IS PRODUCING WIDELY SCATTERED SHOWERS W OF
74W TO THE COAST OF NICARAGUA SOUTH OF 16N. THE EASTERN
CARIBBEAN REMAINS VERY DRY UNDER STRONG SUBSIDENCE ALOFT.
MODERATE TRADE WINDS PERSIST THROUGHOUT THE CENTRAL AND EASTERN
CARIBBEAN.

THE ATLANTIC OCEAN...
A LARGE NON-TROPICAL LOW LOCATED OVER THE NORTH-CENTRAL ATLANTIC
NEAR 37N46W IS SHOWING SIGNS OF ORGANIZATION. THIS SYSTEM IS
SLOWLY ACQUIRING TROPICAL CHARACTERISTICS AND HAS THE POTENTIAL
TO BECOME A SUBTROPICAL OR TROPICAL CYCLONE OVER THE NEXT DAY
OR TWO AS IT MOVES GENERALLY WESTWARD NEAR 10 KT. A DISSIPATING
FRONTAL BOUNDARY ASSOCIATED WITH THIS LOW EXTENDS TO NEAR
29N37W. SCATTERED SHOWERS ASSOCIATED WITH THE LOW AND THE
FRONTAL BOUNDARY EXTEND SOUTHWARD TO 26N BETWEEN 31W-51W. A WEAK
SFC RIDGE COVERS THE WEST-CENTRAL ATLC. THE ONLY CONVECTIVE
ACTIVITY IN THE REGION IS LOCATED BETWEEN THE EAST COAST OF
FLORIDA AND THE BAHAMAS. SCATTERED SHOWERS AND THUNDERSTORMS IN
THIS AREA ARE ASSOCIATED WITH A SFC TROUGH EXTENDING UP THE
FLORIDA PENINSULA FROM A LOW PRESSURE OVER THE YUCATAN. THE
EASTERN ATLC IS DOMINATED BY A SFC RIDGE EXTENDING FROM OVER THE
AZORES. A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE UPPER LEVELS.
THE WESTERN RIDGE IS CENTERED ON AN UPPER HIGH SITUATED TO THE
NE OF THE BAHAMAS NEAR 26N72W. A TROUGH CONNECTS AN UPPER LOW
NEAR 30N47W TO A SECOND LOW EAST OF THE ANTILLES. THE
EASTERNMOST RIDGE IS CENTERED ON AN UPPER HIGH NEAR 18N23W. THIS
RIDGE IS ENHANCING CONVECTION ALONG THE ITCZ.
$$
WADDINGTON








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