[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 131206
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI AUG 13 2010

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...TROPICAL WAVES...

TROPICAL WAVE EXTENDS FROM 10N30W TO 19N39W MOVING W AT 10-15
KT. THE WAVE LOCATION IS BETTER APPARENT IN THE MID LEVELS OF
THE ATMOSPHERE...SUCH AS THE 700 MB GLOBAL MODEL STREAMLINE
ANALYSIS. SATELLITE IMAGERY INDICATES WEAK LOW-LEVEL CYCLONIC
FLOW IN THE VICINITY OF THE WAVE AXIS CONFIRMED BY SATELLITE
DERIVED WINDS. DUE TO A LARGE AREA OF DRY SAHARAN AIR AND DUST
TO THE EAST OF THE WAVE AXIS...CONVECTION IS MAINLY CONSTRAINED
TO THE ITCZ S OF 08N.

TROPICAL WAVE EXTENDS FROM 13N62W TO 22N57W MOVING W-NW AT 10-15
KT. SATELLITE IMAGERY INDICATES BROAD LOW TO MID-LEVEL CYCLONIC
FLOW IN THE VICINITY OF THE WAVE AXIS WITH ELEVATED TOTAL
PRECIPITABLE WATER VALUES FROM 11N-21N BETWEEN 57W-63W. ONGOING
CONVECTION REMAINS LIMITED IN ORGANIZATION DUE TO AN UPPER LEVEL
TROUGH AXIS TO THE NW OF THE WAVE AXIS ALONG 29N56W TO 20N65W.
SCATTERED SHOWERS ARE FROM 18N-23N BETWEEN 56W-61W...WHILE
ISOLATED MODERATE CONVECTION IS OVER THE SE CARIBBEAN FROM
11N-14N BETWEEN 60W-64W.

TROPICAL WAVE EXTENDS FROM 12N78W TO 22N71W MOVING W-NW AT 10-15
KT. TOTAL PRECIPITABLE WATER IMAGERY CONTINUES TO INDICATE
HIGHER VALUES OF MOISTURE AND ASSOCIATED CLOUDINESS OVER THE
NORTH-CENTRAL CARIBBEAN N OF 17N BETWEEN 65W-80W THAT COINCIDES
WITH THE BASE OF AN UPPER LEVEL TROUGH LOCATED NORTH OF
HISPANIOLA AND PUERTO RICO NEAR 20N65W. WIDELY SCATTERED SHOWERS
AND ISOLATED MODERATE CONVECTION ARE FROM 16N-20N BETWEEN
69W-75W.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 11N15W 08N20W 05N51W 11N75W THEN
RESUMING IN THE SW CARIBBEAN SEA NEAR 11N80W TO 11N86W OVER
SW NICARAGUA. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION
IS FROM 05N-09N BETWEEN 08W-22W...AND FROM 10N-12N BETWEEN
15W-20W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF A
LINE FROM 06N22W TO 04N45W. NUMEROUS MODERATE AND SCATTERED
STRONG CONVECTION IS OVER THE SW CARIBBEAN SEA S OF 15N BETWEEN
75W-85W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS EVIDENT ON WATER
VAPOR IMAGERY ACROSS MUCH OF THE GULF AND SE CONUS E OF 96W.
EASTERLY UPPER LEVEL FLOW DOMINATES AND A MOSTLY DRY AND
SUBSIDENT AIRMASS IS COVERING THIS PORTION OF THE GULF. AT THE
SURFACE...EMBEDDED UNDERNEATH THE UPPER LEVEL RIDGE ARE THE
REMNANTS OF T.D. FIVE ANALYZED AS A 1007 MB LOW CENTERED NEAR
30N89W. CONVECTION REMAINS LIMITED IN THE VICINITY OF THE LOW AS
ONLY A FEW ISOLATED SHOWERS AND TSTMS REMAIN N OF 27N BETWEEN
85W-93W. THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF A
SURFACE RIDGE THAT EXTENDS WESTWARD FROM THE W ATLC ALONG 24N TO
THE NE MEXICO COAST. A FEW ISOLATED SHOWERS AND TSTMS ARE
OCCURRING ALONG THE MEXICO COAST FROM 18N-25N W OF 95W DUE TO AN
UPPER LEVEL TROUGH ALONG 103W THAT CONTINUES TO MOVE WESTWARD
ACROSS INTERIOR NORTHERN MEXICO.

CARIBBEAN SEA...
UPPER LEVEL TROUGHING COVERS THE NORTH-CENTRAL CARIBBEAN
SUPPORTING A WEAK SURFACE TROUGH EXTENDING FROM THE FLORIDA
STRAITS NEAR 25N80W ACROSS CENTRAL CUBA TO NEAR 20N80W. LOW-
LEVEL CONVERGENCE NEAR THE SURFACE TROUGH IS SUPPORTING ISOLATED
SHOWERS WITHIN 90 NM OF THE TROUGH AXIS. FARTHER EAST...A
TROPICAL WAVE ANALYZED FROM THE TURKS AND CAICOS ISLANDS THROUGH
THE WINDWARD PASSAGE TO THE SW CARIBBEAN NEAR 12N78W IS
SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 17N BETWEEN
65W-80W. ISOLATED SHOWERS STRETCH FARTHER EAST OVER HISPANIOLA
AND AS FAR EAST AS PUERTO RICO AND THE US/UK VIRGIN ISLANDS TO
64W. THE TROPICAL WAVE IS ALSO PROVIDING A LOW-LEVEL FOCUS FOR
CONVECTION ACROSS THE SW CARIBBEAN AS AN UPPER LEVEL DIFFLUENT
ENVIRONMENT IS NOTED ON WATER VAPOR IMAGERY S OF 15N BETWEEN
75W-85W. ADDING IN FURTHER SURFACE CONVERGENCE WITH THE ITCZ
AXIS ALONG 11N/12N...IT CONTINUES TO ENHANCE THE ONGOING
CONVECTION. ELSEWHERE...THE REMAINDER OF THE CARIBBEAN IS UNDER
GENERALLY FAIR CONDITIONS...HOWEVER WITH THE TROPICAL WAVE
LOCATED ACROSS THE LESSER ANTILLES...INCREASED LOW-LEVEL
MOISTURE AND ISOLATED SHOWERS AND TSTMS ARE EXPECTED TO CONTINUE
OVER THE EASTERN CARIBBEAN E OF 64W OVER THE NEXT 24-36 HOURS.
AN UPPER LEVEL RIDGE AXIS EXTENDING FROM THE TROPICAL NORTH ATLC
NEAR 22N45W TO THE SE CARIBBEAN NEAR 12N62W IS ENHANCING ONGOING
CONVECTION OVER THE WINDWARD ISLANDS S OF 14N BETWEEN 60W-64W.

ATLANTIC OCEAN...
UPPER LEVEL ANTICYCLONIC FLOW DOMINATES THE W ATLC N OF 20N W OF
62W STEMMING FROM AN UPPER LEVEL HIGH CENTERED NEAR 30N82W.
WHILE CONVECTIVE DEBRIS CLOUDINESS ADVECTS SOUTHWARD TO
25N...CONDITIONS REMAIN GENERALLY FAIR DUE TO A SURFACE RIDGE
WITH AXIS ALONG 24N/25N BETWEEN 60W TO THE STRAITS OF FLORIDA
AND INTO THE GULF OF MEXICO. EMBEDDED WITHIN THIS SURFACE
RIDGE...A PAIR OF WEAKNESSES ARE GENERATING AREAS OF MOISTURE
AND PRECIPITATION S OF THE RIDGE AXIS. A SURFACE TROUGH EXTENDS
FROM NEAR 25N80W TO CENTRAL CUBA WITH A FEW ISOLATED SHOWERS
WITHIN 90 NM OF THE TROUGH AXIS. FARTHER EAST...A TROPICAL WAVE
ALONG 72W CONTINUES TO ENHANCE ISOLATED SHOWERS N OF HISPANIOLA
BETWEEN 65W-72W. THE BASE OF AN UPPER LEVEL TROUGH LOCATES NEAR
20N65W AND CONTINUES TO AID IN THE POOLING OF LOW TO MID-LEVEL
MOISTURE AND PROVIDING ADDITIONAL LIFT FOR ISOLATED SHOWERS S OF
23N BETWEEN 63W-77W. THE UPPER LEVEL TROUGH AXIS EXTENDS FROM AN
UPPER LEVEL LOW CENTERED NEAR 29N56W TO 20N65W. THIS UPPER
TROUGHING SUPPORTS ISOLATED SHOWERS FROM 25N-32N BETWEEN
52W-57W. FARTHER EAST...BROAD SURFACE RIDGING DOMINATES THE
EASTERN ATLC ANCHORED BY A 1031 MB SURFACE HIGH PRESSURE CENTER
WELL NORTH OF THE DISCUSSION AREA. THE SURFACE RIDGE AXIS
EXTENDS FROM THE AZORES TO NEAR 20N50W. SATELLITE IMAGERY
TRACKING THE SAHARAN AIR LAYER INDICATES A LARGE AREA COVERING
MOST OF THE EASTERN ATLC N OF 15N E OF 35W SUPPORTING OVERALL
STABLE CONDITIONS. HOWEVER...A PAIR OF SURFACE TROUGHS ARE
LOCATED OVER THE FAR EASTERN ATLC TO INLAND OVER W AFRICA
INDICATING A SHIFT IN WIND DIRECTION. THE FIRST IS ANALYZED
ALONG 22N BETWEEN 14W-26W. A STRONG PRESSURE GRADIENT LOCATED
WITHIN 300 NM OF THE W AFRICA COAST NORTH OF THE SURFACE TROUGH
IS PROVIDING N-NE WINDS TO 25 KT. A SECOND SURFACE TROUGH IS
FROM 14N17W TO 11N22W NORTH OF THE ITCZ AXIS AND IS PROVIDING
FOCUS FOR SCATTERED SHOWERS AND TSTMS FROM 10N-12N BETWEEN
15W-20W.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN




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