[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 060513
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN SEP 06 2009

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
0430 UTC.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 31W/32W S OF 23N MOVING W NEAR 10 KT. A
1012 MB LOW IS EMBEDDED ON THE WAVE AXIS NEAR 18N31W. SATELLITE
IMAGERY AND SATELLITE DERIVED WINDS INDICATE LOW-LEVEL CYCLONIC
FLOW IN THE VICINITY OF THE WAVE AXIS CONCENTRATED AROUND THE
LOW PRESSURE CENTER NEAR 18N. A 2344 UTC ASCAT SCATTEROMETER
PASS CONFIRMS THE LOW-LEVEL CYCLONIC WINDS AROUND THE LOW
CENTER. THE WAVE ALSO COINCIDES WITH A DEEP LAYER MOISTURE
MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 20N-23N BETWEEN 29W-32W.

TROPICAL WAVE IS ALONG 43W S OF 21N MOVING W NEAR 12 KT. A 1012
MB LOW IS ALONG THE WAVE AXIS NEAR 14N43W. SATELLITE IMAGERY AND
SATELLITE DERIVED WINDS INDICATE LOW-LEVEL CYCLONIC FLOW IN THE
VICINITY OF THE WAVE AXIS CONCENTRATED AROUND THE LOW PRESSURE
CENTER NEAR 14N. A 2344 UTC ASCAT SCATTEROMETER PASS CONFIRMS
THE LOW-LEVEL CYCLONIC WINDS AROUND THE WAVE AXIS. THE WAVE
COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED TOTAL
PRECIPITABLE WATER IMAGERY. A DRY SAHARAN AIR LAYER IS TO THE W
OF THE WAVE AXIS WHICH IS LIMITING DEEP CONVECTION TO THE ITCZ
AND A SMALL CLUSTER NEAR THE LOW CENTER. ISOLATED MODERATE
CONVECTION IS FROM 8N-10N BETWEEN 41W-45W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 15N-17N BETWEEN
43W-44W.

TROPICAL WAVE IS ALONG 61W S OF 17N MOVING W NEAR 12 KT. THE
WAVE REMAINS RELATIVELY LOW-AMPLITUDE WITH NO ASSOCIATED
DEEP CONVECTION DUE TO DRY SAHARAN DUST TO THE E OF THE WAVE
AXIS. THE WAVE COINCIDES WITH A NARROW DEEP LAYER MOISTURE
MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 12N16W 16N24W 18N30W 15N38W
10N46W 6N54W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS
FROM 10N-17N BETWEEN 14W-19W. ISOLATED MODERATE CONVECTION IS
FROM 9N-11N BETWEEN 35W-40W.
...DISCUSSION...

GULF OF MEXICO...
THE GULF REMAINS MOIST TONIGHT WITH ISOLATED SHOWERS ACROSS MUCH
OF THE BASIN. A SURFACE TROUGH IS IN THE NW GULF EXTENDING
ACROSS LOUISIANA FROM 31N90W TO 27N94W. SURFACE CONVERGENCE NEAR
THE TROUGH ALONG WITH UPPER LEVEL DIFFLUENCE BETWEEN AN UPPER
RIDGE DOMINATING THE MAJORITY OF THE GULF CENTERED OVER MEXICO
NEAR 18N99W AND AN UPPER LEVEL TROUGH OVER THE CENTRAL UNITED
STATES ARE SUPPORTING ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS NW
OF A LINE FROM 30N85W TO 19N92W INCLUDING THE BAY OF CAMPECHE. A
SHORTWAVE UPPER LEVEL TROUGH IS OVER THE ERN GULF WITH AXIS
ALONG 30N86W TO 22N81W. UPPER LEVEL DIFFLUENCE BETWEEN THIS
UPPER TROUGH AND THE UPPER RIDGE IS ALSO SUPPORTING THE
AFOREMENTIONED SHOWER ACTIVITY. EXPECT SHOWERS/THUNDERSTORMS TO
PERSIST FOR THE NEXT 24 HRS.

CARIBBEAN SEA...
ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE FAR NW CARIBBEAN N
OF 21N BETWEEN 78W-85W IN ASSOCIATION WITH UPPER LEVEL DIFFLUENT
FLOW BETWEEN AN UPPER LEVEL TROUGH OVER THE ERN GULF EXTENDING
TO THE NW CARIBBEAN TO NEAR 18N86W AND AN UPPER LEVEL RIDGE OVER
THE CENTRAL CARIBBEAN CENTERED NEAR 13N75W. THIS UPPER DIFFLUENT
FLOW IS ALSO ENHANCING SCATTERED SHOWERS/THUNDERSTORMS OFF THE
COAST OF NICARAGUA AND HONDURAS FROM 11N-16N BETWEEN 82W-84W. A
SURFACE TROUGH EXTENDS ACROSS ERN CUBA INTO THE CENTRAL
CARIBBEAN FROM 22N75W TO 3N75W. SURFACE CONVERGENCE NEAR THE
TROUGH IS SUPPORTING A FEW ISOLATED SHOWERS ACROSS CUBA AND
HISPANIOLA. MODERATE TO FRESH TRADE WINDS ARE ACROSS MUCH OF THE
BASIN BECOMING STRONG IN THE E CARIBBEAN. OVER THE NEXT 24
HR...EXPECT THE TROPICAL WAVE ALONG 61W TO MOVE INTO THE ERN
CARIBBEAN.

ATLANTIC OCEAN...
ISOLATED SHOWERS/THUNDERSTORMS ARE ACROSS THE W ATLC N OF 28N W
OF 76W. THIS ACTIVITY IS ENHANCED BY UPPER LEVEL DIFFLUENCE
BETWEEN AN UPPER LEVEL TROUGH OVER THE ERN GULF AND AN UPPER
LEVEL RIDGE OVER THE CENTRAL ATLC CENTERED NEAR 33N55W. AN UPPER
LEVEL LOW CENTERED NEAR 28N67W INTRUDES INTO THE SW PORTION OF
THE UPPER RIDGE. THIS UPPER LEVEL LOW SUPPORTS A SURFACE TROUGH
EXTENDING FROM 25N66W TO 29N65W. ISOLATED SHOWERS ARE WITHIN 200
NM EITHER SIDE OF THE TROUGH AXIS. ANOTHER SURFACE TROUGH
EXTENDS FROM THE CARIBBEAN ACROSS ERN CUBA TO NEAR 22N75W.
SURFACE CONVERGENCE NEAR THE TROUGH IS SUPPORTING SCATTERED
SHOWERS/THUNDERSTORMS ACROSS THE BAHAMAS FROM 21N-25N BETWEEN
72W-78W. ISOLATED SHOWERS ARE N OF PUERTO RICO AND THE LEEWARD
ISLANDS FROM 18N-24N BETWEEN 61W-66W. THIS ACTIVITY IS ENHANCED
BY UPPER LEVEL DIFFLUENCE BETWEEN THE AFOREMENTIONED UPPER LEVEL
LOW NEAR 28N67W AND AN UPPER LEVEL RIDGE OVER THE TROPICAL ATLC.
ELSEWHERE ACROSS THE ATLC...A BROAD SURFACE RIDGE DOMINATES
ANCHORED BY A 1024 MB HIGH NEAR 30N53W. IN THE UPPER LEVELS...A
NARROW UPPER LEVEL TROUGH IS E OF THE UPPER HIGH NEAR 33N55W.
THE UPPER TROUGH HAS AXIS ALONG 35N28W TO 20N48W. TO THE E OF
THE TROUGH ANOTHER UPPER LEVEL RIDGE IS CENTERED NEAR 17N25W.

$$
WALTON










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