[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 131740
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE AUG 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 13N35W TO 20N39W MOVING W AT 15 KT.
THE WAVE COINCIDES WITH A BROAD LOW-LEVEL CYCLONIC CIRCULATION
THAT REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AXIS AND FOCUSED
IN THE VICINITY OF A 1010 MB LOW CENTERED NEAR 13N35W. TOTAL
PRECIPITABLE WATER IMAGERY INDICATES MAXIMUM VALUES FROM 11N-19N
BETWEEN 31W-40W. CONVECTION REMAINS LARGELY SUPPRESSED DUE TO
THE EXPANSIVE SAHARAN AIR LAYER COVERING MUCH OF THE CENTRAL AND
EASTERN ATLC.

TROPICAL WAVE EXTENDS FROM 10N63W TO 17N62W MOVING W AT 15-20
KT. THE WAVE REMAINS ON THE LEADING EDGE OF SAHARAN DUST WHICH
IS NOTED ON VISIBLE SATELLITE IMAGERY TO THE EAST OF THE WAVE
AXIS BETWEEN 40W-60W. THIS SAHARAN AIR LAYER IS INHIBITING ANY
DEEP CONVECTION OVER THE LESSER ANTILLES AND EASTERN CARIBBEAN
SEA AT THIS TIME...HOWEVER A FEW ISOLATED SHOWERS AND TSTMS ARE
POSSIBLE FROM 11N-18N BETWEEN 59W-65W.

TROPICAL WAVE EXTENDS FROM 12N81W TO 21N77W MOVING W-NW AT 10-15
KT. THE WAVE CORRESPONDS WITH GENERALLY BROAD CYCLONIC FLOW
ACROSS THE WESTERN CARIBBEAN FOCUSED IN THE VICINITY OF A 1009
MB LOW CENTERED NEAR 12N82W. TOTAL PRECIPITABLE WATER IMAGERY
INDICATES MAXIMUM VALUES S OF 20N BETWEEN 72W-84W WITH SCATTERED
MODERATE CONVECTION NOTED FROM 14N-19N BETWEEN 74W-85W. THE
ECMWF CONTINUES TO MOVE THE WAVE INTO THE WESTERN GULF OF MEXICO
BY LATE THURSDAY WHILE THE GFS REMAINS AGGRESSIVE IN FURTHER
DEVELOPMENT LATE THURSDAY INTO FRIDAY OVER THE CENTRAL AND
EASTERN GULF WATERS. REGARDLESS...THE CURRENT AREA OF
PRECIPITATION AND CONVECTION IS EXPECTED TO MOVE THROUGH THE NW
CARIBBEAN AND YUCATAN CHANNEL LATE WEDNESDAY.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO
14N32W TO 13N36W TO 07N46W. THE INTERTROPICAL CONVERGENCE ZONE
AXIS EXTENDS FROM 07N46W TO 05N53W. SCATTERED MODERATE
CONVECTION IS FROM 10N-15N BETWEEN 16W-25W...AND FROM 09N-13N
BETWEEN 25W-33W.

...DISCUSSION...

GULF OF MEXICO...
NORTHEASTERLY UPPER LEVEL FLOW IS NOTED ON WATER VAPOR IMAGERY
OVER THE GULF THIS AFTERNOON BETWEEN AN UPPER LEVEL ANTICYCLONIC
CIRCULATION CENTERED OVER WESTERN TEXAS NEAR 31N105W AND AN
UPPER LEVEL LOW CENTERED OVER THE NORTHWESTERN TIP OF THE
YUCATAN PENINUSLA NEAR 21N90W. THE UPPER LEVEL LOW EXTENDS A
TROUGH AXIS E-NE TO OVER THE SOUTHERN FLORIDA PENINSULA NEAR
26N81W. OVERALL...A DRIER AIRMASS LIES OVER MUCH OF THE GULF
WITH ONLY A FEW AREAS OF ONGOING CONVECTION NOTED AT THIS TIME.
SCATTERED SHOWERS AND TSTMS ARE OCCURRING ALONG THE NE GULF
COAST FROM 29N-31N BETWEEN 85W-90W...AND OVER THE SOUTH-CENTRAL
GULF FROM 21N-25N BETWEEN 85W-91W. OTHERWISE...A SURFACE RIDGE
ANCHORED BY A 1018 MB HIGH IS CENTERED NEAR 27N88W THAT EXTENDS
A RIDGE AXIS EASTWARD ALONG 27N INTO THE SW NORTH ATLC REGION
AND W-SW TO THE MEXICO COAST NEAR 22N99W. LIGHT ANTICYCLONIC
FLOW IS EXPECTED TO PERSIST THROUGH LATE WEDNESDAY AS A TROPICAL
WAVE EMERGES FROM THE NW CARIBBEAN INTO THE SE AND SOUTH-CENTRAL
GULF WATERS ON THURSDAY. GLOBAL MODELS DIFFER ON EXACT TRACK AND
DEVELOPMENT OF THE WAVE...HOWEVER ONGOING CONVECTION AND
PRECIPITATION OCCURRING ACROSS THE WESTERN CARIBBEAN WILL SHIFT
INTO THE GULF BY THE WEEKEND.

CARIBBEAN SEA...
AN UPPER LEVEL LOW AND ASSOCIATED TROUGHING IS CENTERED OVER THE
YUCATAN PENINSULA AND SE GULF OF MEXICO PROVIDING MOIST
SOUTHWESTERLY FLOW ALOFT OVER THE NW CARIBBEAN. AS A RESULT OF
THE MIDDLE TO UPPER DIFFLUENCE ACROSS THIS REGION...WIDELY
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING NW OF A LINE
FROM 22N80W TO 18N88W. TO THE SOUTHEAST...AN UPPER LEVEL
ANTICYCLONIC CIRCULATION IS CENTERED NEAR 16N77W AND REMAINS
ABOVE A TROPICAL WAVE AT THE SURFACE EXTENDING FROM THE SW
CARIBBEAN NORTH-NORTHEASTWARD TO EASTERN CUBA. LOW-LEVEL
MOISTURE CONVERGENCE AND MAXIMUM MIDDLE TO UPPER LEVEL
DIFFLUENCE IS GENERATING NUMEROUS SHOWERS AND SCATTERED TSTMS
FROM 13N-20N BETWEEN 74W-86W. THE WAVE IS FORECAST TO TRACK W-NW
TOWARDS THE YUCATAN PENINSULA AND YUCATAN CHANNEL ENTERING THE
SOUTHERN GULF OF MEXICO BY THURSDAY. FINALLY...NORTHERN UPPER
LEVEL FLOW DOMINATES OVER THE EASTERN CARIBBEAN AND IS PROVIDING
RELATIVELY STABLE AND FAIR CONDITIONS E OF 70W. A WEAK TROPICAL
WAVE ANALYZED ALONG 62W HOWEVER CONTINUES TO PROVIDE ISOLATED
SHOWERS OVER THE LESSER ANTILLES AND NE CARIBBEAN THIS
AFTERNOON.

HISPANIOLA...
CURRENTLY LOW-LEVEL MOISTURE AND ISOLATED SHOWERS ARE OCCURRING
ACROSS THE SOUTHERN PORTION OF THE ISLAND...LEFTOVER MOISTURE
FROM THE PASSAGE OF THE TROPICAL WAVE OVER THE PAST 24 HOURS
WHICH HAS NOW MOVED INTO THE WESTERN CARIBBEAN SEA. WITH E-SE
SURFACE WINDS PERSISTING AND CONTINUED ADVECTION OF LOW-LEVEL
MOISTURE...PEAK HEATING AND INSTABILITY WILL PROVIDE THE
OPPORTUNITY FOR AFTERNOON AND EVENING SCATTERED SHOWERS AND
TSTMS.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED
NEAR 31N73W THAT INFLUENCES A LARGE PORTION OF THE SW NORTH ATLC
W OF 68W THIS AFTERNOON. THE RIDGING ALOFT CONTINUES TO SUPPORT
A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM 29N68W WESTWARD
INTO THE NORTHERN GULF OF MEXICO ALONG 28N. MOSTLY FAIR SKIES
AND CONDITIONS ACCOMPANY THIS FEATURE AS WATER VAPOR IMAGERY
INDICATES AN AREA OF MODERATE TO STRONG DRY AIR AND SUBSIDENCE
STRETCHING FROM NE OF THE TURKS AND CAICOS NEAR 23N70W TO THE
FLORIDA PENINSULA. FARTHER EAST ACROSS THE CENTRAL ATLC...A
VIGOROUS UPPER LEVEL LOW IS CENTERED NEAR 29N60W AND SUPPORTS A
SURFACE TROUGH ANALYZED FROM 25N58W TO 29N57W. SCATTERED SHOWERS
AND ISOLATED TSTMS ARE OCCURRING FROM 24N-32N BETWEEN 55W-68W IN
ASSOCIATION WITH BOTH THE FEATURES AT THE SURFACE AND ALOFT.
OTHERWISE...FAIRLY BENIGN CONDITIONS ARE NOTED ON SATELLITE
IMAGERY E OF 55W AS A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH
CENTERED NEAR 33N43W DOMINATES THE OVERALL PATTERN. ASIDE FROM
THE TROPICAL WAVES DISCUSSED IN DETAIL ABOVE...AN AREA OF
SAHARAN DUST IS LOCATED GENERALLY N OF 15N E OF 55W.

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

$$
HUFFMAN


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