[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 061155
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT AUG 06 2011

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...WEATHER OBSERVATIONS...RADAR...AND
METEOROLOGICAL ANALYSIS.

BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1115 UTC.

...SPECIAL FEATURE...

THE REMNANTS OF EMILY CONTINUE TO IMPACT THE CENTRAL BAHAMAS.
CURRENTLY A 1012 MB LOW IS ANALYZED N OF CENTRAL CUBA NEAR
23N79W MOVING NW-N NEAR 10-12 KT. A SURFACE TROUGH EXTENDS
THROUGH THE LOW CENTER FROM NEAR 27N76W TO THE LOW CENTER.
A LARGE CLUSTER OF MODERATE/STRONG CONVECTION HAS FLARED UP
NEAR THE CENTER AND TO THE NE FROM 23N-25N BETWEEN 76W-79W.
UPPER LEVEL WINDS ARE FAVORABLE FOR SOME DEVELOPMENT AND
A TROPICAL DEPRESSION COULD FORM LATER TODAY. AN AIR FORCE
PLANE IS SCHEDULED TO INVESTIGATE THE LOW THIS AFTERNOON.
EVEN IF THE SYSTEM BECOMES A TROPICAL DEPRESSION...ENVIRONMENTAL
CONDITIONS ARE ONLY MARGINAL...AND DO NOT FAVOR SIGNIFICANT
INTENSIFICATION.  REGARDLESS OF DEVELOPMENT...THIS DISTURBANCE
WILL BRING SQUALLS AND LOCALLY HEAVY RAINFALL TO PORTIONS OF
THE NORTHWESTERN BAHAMAS TODAY AS IT MOVES NORTHWARD OVER
THE NORTHERN BAHAMAS AND INTO THE OPEN ATLANTIC DURING
THE NEXT DAY OR TWO.

...TROPICAL WAVES...

TROPICAL WAVE IS ACROSS THE CENTRAL TRPCL ATLC WITH A NEGATIVE
TILT ALONG 14N36W TO 11N33W MOVING W AT 15-20 KT. SLIGHT
CURVATURE IN THE LOW LEVEL WINDS IS AROUND THE WAVE AXIS ALSO
INDICATED BY SATELLITE DERIVED WINDS. NO DEEP CONVECTION IS
CURRENTLY ASSOCIATED WITH THE WAVE.

TROPICAL WAVE IS E OF THE LESSER ANTILLES ALONG 15N51W TO 10N54W
MOVING W 15-20 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF DEEP
LAYER MOISTURE AND AHEAD OF A BROAD NWD SURGE OF DEEP LAYER
MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. BROAD
CYCLONIC FLOW IS ALSO AROUND THE WAVE AXIS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 12N-15N BETWEEN
50W-54W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 12N-14N
BETWEEN 56W-59W.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM W AFRICAN COAST NEAR 19N16W
ALONG 11N20W 12N27W 11N32W. THE ITCZ CONTINUES ON THE OTHER SIDE
OF A TROPICAL WAVE ALONG 11N34W 14N43W 13N51W. NUMEROUS
MODERATE/SCATTERED STRONG CONVECTION IS OFF THE W AFRICAN COAST
FROM 8N-14N BETWEEN 15W-19W MOST LIKELY ASSOCIATED WITH THE NEXT
TROPICAL WAVE THAT WILL MOVE OFF THE COAST DURING THE NEXT DAY.
SCATTERED MODERATE CONVECTION IS FROM 6N-8N BETWEEN 22W-30W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF OF MEXICO REMAINS MOSTLY DRY THIS MORNING INFLUENCED
BY DRY AIR ALOFT BEING DRAWN FROM THE NW CARIBBEAN AROUND AN
UPPER LEVEL LOW CENTERED OVER SRN MEXICO NEAR 18N96W WITH
TROUGH AXIS EXTENDING TO CENTRAL FLORIDA NEAR 28N81W. AN UPPER
LEVEL RIDGE CENTERED OVER TEXAS IS PROVIDING NELY FLOW OVER THE
NW GULF. A WEAK PRESSURE GRADIENT IS ACROSS THE BASIN SUPPORTING
WEAK E-SE FLOW. A CLUSTER OF SHOWERS/THUNDERSTORMS ARE CURRENTLY
N OF THE FLORIDA KEYS FROM 24N-25N BETWEEN 81W-82W. A FEW
ISOLATED SHOWERS ARE ALSO ALONG THE N CENTRAL GULF N OF 27N
BETWEEN 92W-94W. EXPECT WEAK SURFACE RIDGING TO FORM OVER THE
ERN PORTION OF THE BASIN OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
A SURFACE TROUGH IS ACROSS THE NW CARIBBEAN FROM S OF CUBA NEAR
20N83W TO 16N84W. HOWEVER...NO STRONG SHOWER ACTIVITY IS
ASSOCIATED WITH IT DUE TO STRONG DRY AIR ALOFT INDICATED BY
WATER VAPOR IMAGERY. THE DRY AIR IS BEING WRAPPED AROUND AN
UPPER LEVEL TROUGH ACROSS THE SRN GULF OF MEXICO. A SMALL
CLUSTER OF SHOWERS/THUNDERSTORMS IS NEAR THE SRN EXTENT OF THE
SURFACE TROUGH OVER HONDURAS. UPPER RIDGING COVERS THE WRN
CARIBBEAN CENTERED OVER HONDURAS NEAR 15N86W. MOST OF THE
SHOWER/THUNDERSTORM ACTIVITY ASSOCIATED WITH THE REMNANTS OF
EMILY HAVE NOW MOVED N OF THE BASIN EXCEPT FOR A FEW SHOWERS
FROM 19N-21N BETWEEN 77W-79W. SCATTERED SHOWERS/THUNDERSTORMS
HAVE ALSO DEVELOPED OVER COSTA RICA AND PANAMA ASSOCIATED WITH
THE MONSOON TROUGH THAT EXTENDS FROM THE E PACIFIC ACROSS COSTA
RICA TO NRN COLOMBIA. THE REMAINDER OF THE BASIN IS UNDER MOSTLY
FAIR CONDITIONS WITH NE-E TRADEWIND FLOW NEAR 20 KT. A FEW
ISOLATED SHOWERS ARE EMBEDDED IN THIS TRADEWIND FLOW FROM
15N-17N BETWEEN E OF 66W. ALOFT...WEAK UPPER TROUGHING COVERS
THE ERN CARIBBEAN EXTENDING FROM THE ATLC. EXPECT THE SURFACE
TROUGH IN THE NW CARIBBEAN TO DISSIPATE OVER THE NEXT 24 HOURS.
A TROPICAL WAVE E OF THE LESSER ANTILLES WILL BEGIN TO IMPACT
THE ERN CARIBBEAN DURING THE NEXT 24 HOURS. SOME SHOWER ACTIVITY
IS WELL AHEAD OF THE WAVE ALMOST APPROACHING THE ISLANDS.

ATLANTIC OCEAN...
SHOWERS/THUNDERSTORMS ASSOCIATED WITH THE REMNANTS OF EMILY ARE
IMPACTING MUCH OF THE CENTRAL BAHAMAS FROM 23N-26N BETWEEN
76W-80W. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. A CLUSTER
OF ACTIVITY IS ALSO FROM 24N-27N BETWEEN 73W-75W. A LARGE AREA
OF DUST IS TO THE E OF THIS AREA OF ACTIVE WEATHER BETWEEN
55W-65W. ALOFT...AN UPPER LEVEL RIDGE IS CENTERED TO THE N NEAR
32N75W WHILE UPPER LEVEL TROUGHING IN THE SRN GULF EXTENDS
ACROSS CENTRAL FLORIDA. AN UPPER LEVEL TROUGH TO THE NE ALONG
55W THAT EXTENDS SWD TO 30N SUPPORTS A FRONTAL BOUNDARY N OF THE
AREA THAT IS ENHANCING SCATTERED SHOWERS/THUNDERSTORMS N OF 29N
BETWEEN 50W-56W. A DRY UPPER LEVEL TROUGH IS ACROSS THE CENTRAL
ATLC ALONG 32N42W TO 20N60W. BROAD UPPER RIDING COVERS MUCH OF
THE REMAINDER OF THE BASIN CENTERED NEAR 21N39W SUPPORTING A
SURFACE RIDGE AROUND A 1026 MB HIGH NEAR 33N34W. A SECOND UPPER
LEVEL RIDGE IS CENTERED N OF THE CANARY ISLANDS NEAR 36N12W.
ANOTHER AREA OF AFRICAN DUST EXTENDS N OF THE TROPICAL WAVES
FROM 15N-20N E OF 40W.

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

$$
WALTON




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