[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021801
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU OCT 02 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
1545 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 43W FROM 09N TO 18N MOVING W NEAR 10 KT.
WAVE IS WELL DEFINED AS A BROAD VORT MAX IN THE GFS AT 700 MB AS
WELL AS IN THE TPW IMAGERY.  DEEP CONVECTION HAS DIMINISHED WITH
THIS SYSTEM DURING THE MORNING...THOUGH SCATTERED SHOWERS ARE
LOCATED WITHIN 120 NMI ON EITHER SIDE OF THE WAVE AXIS.

TROPICAL WAVE IS ALONG 52W FROM 09N TO 19N MOVING W NEAR 10 KT.
WAVE IS NOT DEPICTED IN THE GFS APPRECIABLY...BUT IS APPARENT IN
THE CIMSS WAVETRAK LOW-LEVEL VORTICITY WITH A VORT MAX NEAR
12N53W.  THROUGH THE SPACING BETWEEN THIS WAVE AND THE ONE
FARTHER EAST IS SOMEWHAT THIN...THE TPW IMAGERY HAS CONSISTENTLY
SHOWN A DRY SLOT BETWEEN THE TWO WAVES IN ADDITION TO
SUBSTANTIALLY DRIER LOW LEVEL AIR TO THE NORTHWEST OF THIS WAVE.
ISOLATED SHOWERS ARE WITHIN 120 NM EITHER SIDE OF THE WAVE AXIS.

THE TROPICAL WAVE PREVIOUSLY INDICATED ALONG 69W S OF 16N HAS
BEEN DROPPED FROM THE ANALYSIS AS THERE IS NO EVIDENCE OF THE
WAVE EXISTING FROM RAWINSONDES...TPW...AND LOW-LEVEL VORTICITY
FIELDS.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 12N16W 10N25W 14N41W 13N51W
10N62W. SCATTERED MODERATE CONVECTION EXISTS WITHIN 300 NM SOUTH
OF THE AXIS FROM THE WEST AFRICAN COAST WESTWARD TO 28W.
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION EXISTS WITHIN
120 NM NORTH OF THE AXIS FROM THE WEST AFRICAN COAST WESTWARD TO
22W. ISOLATED MODERATE CONVECTION EXISTS WITHIN 180 NM SOUTH OF
THE AXIS FROM 50W WESTWARD TO THE SOUTH AMERICAN COAST.

...DISCUSSION...

GULF OF MEXICO...A COLD FRONT EXTENDS FROM SW FLORIDA ACROSS THE
GULF TO THE BAY OF CAMPECHE.  AHEAD OF THE FRONT...WEAK
NORTHEASTERLIES ARE OCCURRING DUE TO THE PRE-EXISTING TROUGH
OVER THE NW CARIBBEAN.  ISOLATED SHOWERS...BUT NO DEEP
CONVECTION...IS OBSERVED WITHIN 60 NM OF THE FRONTAL BOUNDARY.
MODEST NORTHERLY WINDS BEHIND THE FRONT ARE FOLLOWED BY WEAK
EASTERLIES IN THE NORTHERN GULF.  THE RESULTING DRY STABLE AIR
IS PREVENTING ANY DEEP CONVECTION OVER THE GULF.  IN THE UPPER
LEVELS...A RELATIVELY STRONG...FOR THIS TIME OF YEAR...
SHORT-WAVE TROUGH EXTENDS FROM THE SE UNITED STATES
SOUTH-SOUTHWESTWARD INTO THE CENTRAL GULF OF MEXICO.

CARIBBEAN SEA...A VIGOROUS SURFACE TROUGH EXTENDS FROM CENTRAL
AMERICA...ACROSS THE NW CARIBBEAN SEA...AND THROUGH CUBA AND THE
BAHAMAS.  NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION
EXISTS WITHIN 180 NM ON EITHER SIDE OF THE TROUGH AXIS.
ELSEWHERE...ISOLATED MODERATE CONVECTION IS ALSO OCCURRING IN
THE SW CARIBBEAN SEA...JUST NORTH OF VENEZUELA...AND OVER AND
JUST SOUTH OF HISPANIOLA.  A WEAK 1009 MB SURFACE LOW IS
ANALYZED JUST NORTH OF HONDURAS...THOUGH THIS MAY BE PRIMARILY A
MID-LEVEL VORT MAX.  IN THE UPPER LEVELS...WEAK RIDGING EXISTS
OVER THE NW CARIBBEAN JUST SOUTH OF THE SURFACE TROUGH.  AN
UPPER TROUGH AXIS EXISTS FROM NEAR HISPANIOLA SOUTHEASTWARD TO
NEAR BARBADOS.

ATLANTIC OCEAN...A COLD FRONT EXTENDS FROM SOUTHEAST FLORIDA
NORTHEASTWARD TO 32N74W.  AHEAD OF THE FRONT...
NORTHWESTERLIES ARE OCCURRING DUE TO A PRE-EXISTING TROUGH THAT
EXTENDS FROM CENTRAL CUBA TO 32N69W.  ISOLATED SHOWERS...BUT NO
DEEP CONVECTION...IS OBSERVED WITHIN 60 NM OF THE FRONTAL
BOUNDARY.  IN CONTRAST...NUMEROUS MODERATE CONVECTION EXISTS
WITHIN 60 NM ON THE WEST SIDE OF THE TROUGH AND WITHIN 120 NM ON
THE EAST SIDE OF THE TROUGH.  A LOW LEVEL MOISTURE PLUME
ASSOCIATED WITH THIS TROUGH IS STRONGLY EVIDENT IN THE TPW
IMAGERY.  WINDS ON THE EAST SIDE OF THE TROUGH AXIS ARE SOUTH TO
SOUTHWEST UP TO 25 KT.  FARTHER EAST...A SURFACE TROUGH HAS
FORMED EXTENDING FROM 24N41W TO 30N38W.  SCATTERED MODERATE
CONVECTION IS OCCURRING WITHIN 120 NM EAST OF THE TROUGH AXIS.
IN THE UPPER LEVELS...A PRONOUNCED HIGH IS CENTERED NEAR 27N63W
WITH RIDGE AXIS EXTENDING SW TOWARD HISPANIOLA AND NE TO
32N57W.  FARTHER EAST...A VIGOROUS MID TO UPPER LOW IS CENTERED
NEAR 27N43W...WHICH IS THE UPPER LEVEL FORCING OF THE
EASTERNMOST SURFACE TROUGH.  A SECOND UPPER LOW IS CENTERED NEAR
17N55W.  UPPER RIDGING IS SEEN FROM 40W EASTWARD ALONG 15N.

$$
LANDSEA




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