[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211047
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED AUG 21 2013

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
1015 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM A 1010 MB LOW CENTERED NEAR 11N34W TO
15N35W TO 19N33W MOVING W AT 10-15 KT. THE LOW CENTER REMAINS
THE FOCAL POINT FOR A BROAD AND ENLONGATED MONSOONAL GYRE
CIRCULATION INFLUENCING THE TROPICAL ATLC FROM 08N-17N BETWEEN
27W-47W. NO SIGNIFICANT DEEP CONVECTION IS OCCURRING IN THE
VICINITY OF THE WAVE HOWEVER SCATTERED MODERATE CONVECTION IS
FROM 07N-10N BETWEEN 32W-40W IN ASSOCIATION WITH THE MONSOON
TROUGH AXIS.

TROPICAL WAVE EXTENDS FROM 10N73W TO 20N72W MOVING W AT 10 KT.
THE WAVE REMAINS WITHIN BROAD LOW-LEVEL...700 MB...TROUGHING
LOCATED ACROSS THE CENTRAL CARIBBEAN SEA WITH TOTAL PRECIPITABLE
WATER IMAGERY INDICATING A LOCAL MAXIMUM FROM 11N-21N BETWEEN
66W-72W. SCATTERED MODERATE CONVECTION IS OCCURRING NEAR THE
SOUTHERN EXTENT OF THE WAVE AXIS FROM 07N-11N BETWEEN 71W-76W
AND IS LIKELY ENHANCED DUE TO THE CLOSE PROXIMITY OF THE MONSOON
TROUGH AXIS EXTENDING ALONG 10N ACROSS NORTHERN COLOMBIA.

TROPICAL WAVE EXTENDS FROM 18N93W TO 27N92W MOVING W AT 10 KT.
THE WAVE IS BECOMING MORE AND MORE DIFFICULT TO DISCERN ON
SATELLITE IMAGERY AND CONTINUES WEAKENING THIS MORNING. ANY
REMAINING TROUGHING IS EXPECTED TO DRIFT WESTWARD AND DISSIPATE
OVER THE NEXT 12 TO 24 HOURS ACROSS THE WESTERN GULF OF MEXICO.
NO SIGNIFICANT DEEP CONVECTION IS ASSOCIATED WITH THE WAVE AT
THIS TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM 18N22W TO 11N34W TO 07N48W. THE
INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N48W TO
07N58W. ISOLATED MODERATE CONVECTION IS FROM 08N-11N BETWEEN 14W-
18W...AND FROM 11N-13N BETWEEN 22W-27W. SCATTERED MODERATE
CONVECTION IS FROM 07N-10N BETWEEN 32W-40W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LOW IS CENTERED OVER NORTHERN MEXICO NEAR 25N102W
AND IS PROVIDING ADVECTION OF MOISTURE ACROSS CENTRAL MEXICO
INTO THE WESTERN GULF. WHILE NO SURFACE FORCING FEATURE IS
PRESENT...AMPLE MIDDLE TO UPPER LEVEL DYNAMICS ARE IN PLACE TO
GENERATE ISOLATED SHOWERS AND TSTMS S OF 28N W OF 95W THIS
MORNING. TO THE EAST...A TROPICAL WAVE WHICH IS BECOMING DIFFUSE
IS ALONG 93W AND EXTENDS WEAK SURFACE TROUGHING FROM THE
LOUISIANA COAST ALONG THE WAVE AXIS TO SOUTHERN MEXICO. THIS
RELATIVELY NARROW AREA OF CYCLONIC TURNING IN THE LOWER LEVELS
OF THE ATMOSPHERE IS GENERATING ISOLATED SHOWERS AND TSTMS FROM
22N-29N BETWEEN 88W-93W. FINALLY...OVER THE EASTERN GULF...
NORTHERLY UPPER LEVEL FLOW DOMINATES ON THE WESTERN PERIPHERY OF
AN UPPER LEVEL LOW CENTERED OVER THE NW CARIBBEAN SEA NEAR
20N84W THAT EXTENDS A TROUGH AXIS NORTHWARD OVER THE SOUTHERN
FLORIDA PENINSULA TO 27N83W. OVERALL UPPER LEVEL CYCLONIC
TURNING...A MID-LEVEL VORTICITY MAXIMUM IN THE VICINITY OF
26N85W...AND LACK OF ANY STRONG PRESSURE GRADIENT AT THE SURFACE
IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS THIS
MORNING E OF 88W...INCLUDING THE FLORIDA STRAITS. LOOKING
AHEAD...GENERALLY EAST-SOUTHEAST WINDS ARE EXPECTED TO PREVAIL
THROUGH THE REMAINDER OF THE WEEK AS A SURFACE RIDGE CONTINUES
TO ANCHOR ITSELF IN THE SW NORTH ATLC WATERS NEAR 32N72W.

CARIBBEAN SEA...
AN UPPER LEVEL LOW IS CENTERED OVER THE NW CARIBBEAN NEAR 20N84W
THAT CONTINUES TO GENERATE ISOLATED SHOWERS AND TSTMS N OF 19N
BETWEEN 78W-86W...INCLUDING THE CAYMAN ISLANDS AND CUBA THIS
MORNING. OTHERWISE...TO THE SOUTHEAST OF THE UPPER LEVEL
LOW...SOUTH-SOUTHWESTERLY FLOW ALOFT DOMINATES ACROSS THE SW
CARIBBEAN. LOW-LEVEL MOISTURE CONVERGENCE ALONG WITH THE
DIFFLUENT ENVIRONMENT PRESENT OVER THE REGION IS GENERATING
SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS S OF 16N BETWEEN
78W-89W. CONVECTION STRETCHES SOUTH OF THIS AREA ACROSS PORTIONS
OF PANAMA AND COSTA RICA AS THE MONSOON TROUGH AXIS EXTENDS
ALONG 10N FROM NORTHERN COLOMBIA INTO THE EAST PACIFIC REGION.
ACROSS THE CENTRAL CARIBBEAN...A TROPICAL WAVE IS ALONG 73W AND
REMAINS EMBEDDED WITHIN BROAD LOW-LEVEL TROUGHING. WITH DEEP
TROPICAL MOISTURE NOTED ON TOTAL PRECIPITABLE WATER IMAGERY...
ISOLATED SHOWERS AND TSTMS ARE OCCURRING S OF 20N BETWEEN 68W-
75W. THE WAVE IS EXPECTED TO CONTINUE MOVING WESTWARD AND
INCREASE PRECIPITATION CHANCES FOR THE WESTERN CARIBBEAN OVER
THE NEXT 24 TO 48 HOURS. FINALLY...A WEAK SURFACE TROUGH
ANALYZED FROM 12N58W TO 16N59W CONTINUES TO PROVIDE ISOLATED
SHOWERS AND TSTMS FOR THE LESSER ANTILLES AND ADJACENT COASTAL
WATERS S OF 18N BETWEEN 57W-65W. THIS AREA OF CONVECTION IS
LIKELY ENHANCED DUE TO MARGINAL MIDDLE TO UPPER LEVEL DIFFLUENCE
LOCATED OVER THE TROPICAL ATLC AND EASTERN CARIBBEAN.

HISPANIOLA...
EARLIER LATE EVENING AND OVERNIGHT CONVECTION CONTINUES TO
DIMINISH WITH ONLY A FEW REMAINING ISOLATED SHOWERS OCCURRING
ACROSS THE ISLAND THIS MORNING. WESTERLY FLOW ALOFT REMAINS OVER
THE ISLAND ON THE NORTHERN PERIPHERY OF AN UPPER LEVEL
ANTICYCLONIC CIRCULATION CENTERED OVER THE CENTRAL CARIBBEAN.
WITH MARGINAL MIDDLE TO UPPER LEVEL LIFT PRESENT AND A TROPICAL
WAVE ALONG 73W...ISOLATED SHOWERS AND TSTMS ARE EXPECTED OVER
THE NEXT 24 HOURS WITH STRONGER SCATTERED CONVECTION EXPECTED TO
INITIATE DURING THE AFTERNOON HOURS DUE TO PEAK DAYTIME HEATING
AND INSTABILITY. ANY ACTIVITY THAT FORMS WILL LIKELY LAST INTO
THE EVENING HOURS AND DIMINISH THEREAFTER.

ATLANTIC OCEAN...
A WEAK UPPER LEVEL LOW IS CENTERED OVER THE SOUTHERN FLORIDA
PENINSULA NEAR 26N82W THAT CONTINUES TO PRODUCE ENHANCEMENT FOR
WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING S OF 29N W
OF 72W ACROSS PORTIONS OF THE SW NORTH ATLC. THIS ACTIVITY
REMAINS ON THE SOUTHWESTERN PERIPHERY OF A SURFACE RIDGE
ANCHORED BY A 1021 MB HIGH CENTERED WEST OF BERMUDA NEAR 32N69W.
THE SURFACE HIGH IS LARGELY SUPPORTED BY A MIDDLE TO UPPER LEVEL
ANTICYCLONIC CIRCULATION CENTERED OVERHEAD NEAR 31N70W. FARTHER
EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 27N56W WITH A TROUGH
AXIS EXTENDING NORTHEAST TO BEYOND 32N51W AND SOUTHWEST TO A
BASE NEAR 20N67W. MID-LATITUDE MOISTURE ASSOCIATED WITH A COLD
FRONTAL BOUNDARY ALONG 31N/32N BETWEEN 55W-65W CONTINUES TO
ADVECT SOUTHWARD ON THE WESTERN PERIPHERY OF THE UPPER LEVEL LOW
PRODUCING ISOLATED SHOWERS FROM 27N-32N BETWEEN 55W-65W.
OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1021 MB
HIGH CENTERED SOUTH OF THE AZORES NEAR 34N28W. THE RIDGE AXIS
EXTENDS SOUTHWEST FROM THE HIGH TO NEAR 27N50W.

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

$$
HUFFMAN


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