[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 141735
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED AUG 14 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.

...SPECIAL FEATURES...
TROPICAL WAVE EXTENDS FROM 13N21W TO 18N20W MOVING W AT 10-15
KT. THE WAVE REMAINS EMBEDDED WITHIN THE MONSOON TROUGH WITH A
LOW-LEVEL CYCLONIC CIRCULATION FOCUSED ON A 1009 MB LOW CENTERED
NEAR 13N21W. AN EARLY MORNING ASCAT PASS AROUND 14/1122 UTC
INDICATED THE PRESENCE OF THE LOW-LEVEL CIRCULATION AND THE WAVE
AXIS WITH 20-30 KT SOUTH-SOUTHWESTERLY WINDS WITHIN 210 NM OF
THE SE SEMICIRCLE OF THE LOW CENTER. SCATTERED MODERATE
CONVECTION IS FROM 09N-14N BETWEEN 18W-30W.

TROPICAL WAVE EXTENDS FROM 13N83W TO 23N83W MOVING W-NW AT 10-15
KT. THE WAVE CORRESPONDS WITH BROAD CYCLONIC FLOW ACROSS THE NW
CARIBBEAN FOCUSED IN THE VICINITY OF A 1009 MB LOW CENTERED NEAR
17N83W. FURTHER DEVELOPMENT AND ORGANIZATION OF CONVECTION
ASSOCIATED WITH THE WAVE IS EXPECTED OVER THE NEXT FEW DAYS AS
THE SYSTEM MOVES TOWARD THE YUCATAN CHANNEL AND PENINSULA AND
EVENTUALLY INTO THE GULF OF MEXICO. SCATTERED MODERATE
CONVECTION IS OCCURRING FROM 12N-23N BETWEEN 80W-87W.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 12N43W TO 19N39W MOVING W AT 15 KT.
THE WAVE COINCIDES WITH A BROAD LOW-LEVEL CYCLONIC FLOW THAT
REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AXIS BETWEEN 35W-50W.
TOTAL PRECIPITABLE WATER IMAGERY INDICATES MAXIMUM VALUES FROM
08N-18N BETWEEN 32W-45W. CONVECTION REMAINS LARGELY SUPPRESSED
DUE TO THE EXPANSIVE SAHARAN AIR LAYER COVERING MUCH OF THE
CENTRAL AND EASTERN ATLC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO
13N21W TO 12N24W TO 14N36W TO 08N52W. THE INTERTROPICAL
CONVERGENCE ZONE AXIS EXTENDS FROM 08N52W TO 09N64W. SCATTERED
MODERATE CONVECTION IS FROM 09N-14N BETWEEN 18W-30W...FROM 09N-
12N BETWEEN 34W-40W...AND FROM 09N-13N BETWEEN 44W-51W. WIDELY
SCATTERED MODERATE CONVECTION IS WITHIN 150 NM N OF THE AXIS
BETWEEN 57W-64W.

...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 NORTHERN MEXICO NEAR 30N107W AND A
VERY NARROW UPPER LEVEL TROUGH AXIS EXTENDING FROM OVER THE NE
GULF NEAR 29N83W SW TO AN UPPER LEVEL LOW OVER INLAND EAST-
CENTRAL MEXICO NEAR 19N99W. OVERALL...THIS IS PROVIDING THE GULF
WITH A MODERATELY DRY AIRMASS ALOFT WITH ONLY A FEW AREAS OF
ONGOING CONVECTION NOTED ON SATELLITE IMAGERY AT THIS TIME.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING ACROSS THE
NORTH-CENTRAL GULF COAST N OF 29N BETWEEN 86W-92W...AND ISOLATED
SHOWERS ARE OCCURRING ACROSS THE SW GULF S OF 21N BETWEEN 93W-
97W. OTHERWISE...A SURFACE RIDGE ANCHORED BY A 1016 MB HIGH
CENTERED NEAR 27N91W AT 14/1500 UTC EXTENDS A RIDGE AXIS
EASTWARD ALONG 27N INTO THE SW NORTH ATLC REGION AND SW TO THE
MEXICO COAST NEAR 22N98W. LIGHT AND VARIABLE WINDS IN THE RANGE
OF 5-10 KT ARE EXPECTED TO GRADUALLY BECOME MORE NORTHEASTERLY
BY LATE WEDNESDAY AS A TROPICAL WAVE AND ASSOCIATED LOW PRESSURE
CENTER MOVES INTO THE YUCATAN CHANNEL REGION AND ACROSS THE
YUCATAN PENINSULA THROUGH THURSDAY. GLOBAL MODELS CONTINUE TO
DIFFER SLIGHTLY ON EXACT TRACK OF THIS FEATURE...HOWEVER ONGOING
CONVECTION AND PRECIPITATION OCCURRING ACROSS THE WESTERN
CARIBBEAN WILL SHIFT INTO THE GULF THIS WEEKEND.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 20N80W
THAT IS PROVIDING A BROAD AREA OF MIDDLE TO UPPER DIFFLUENCE
OVER THE NW CARIBBEAN. AT THE SURFACE...THE SPECIAL FEATURES
TROPICAL WAVE AND ASSOCIATED LOW PRESSURE AREA IS LOCATED
BENEATH THIS FEATURE AND MOVING AROUND THE SOUTHWESTERN
PERIPHERY OF THE RIDGE. NUMEROUS SHOWERS AND SCATTERED TSTMS ARE
OCCURRING FROM 12N-23N BETWEEN 80W-88W. THIS AREA OF
PRECIPITATION AND CONVECTION IS FORECAST TO MOVE W-NW OVER THE
NEXT 48 HOURS IMPACTING THE GULF OF HONDURAS...BELIZE...NORTHERN
GUATEMALA...AND THE YUCATAN PENINSULA AND CHANNEL. FARTHER
SOUTH...THE MONSOON TROUGH AXIS EXTENDS ACROSS PANAMA AND COSTA
RICA THEN INTO THE EAST PACIFIC REGION WITH ONLY A FEW ISOLATED
SHOWERS AND TSTMS OCCURRING FROM 08N-11N BETWEEN 81W-84W.
FINALLY...NORTHERLY UPPER LEVEL FLOW DOMINATES OVER THE CENTRAL
CARIBBEAN AND IS PROVIDING RELATIVELY STABLE AND FAIR CONDITIONS
E OF 75W THIS AFTERNOON. ONE EXCEPTION TO THIS IS A FEW ISOLATED
SHOWERS AND TSTMS OCCURRING OVER THE SE CARIBBEAN S OF 12N
BETWEEN 60W-68W WHICH IS LARGELY ASSOCIATED WITH THE ITCZ AXIS
ANALYZED ACROSS NE VENEZUELA.

HISPANIOLA...
CURRENTLY LOW-LEVEL MOISTURE AND ISOLATED SHOWERS ARE OCCURRING
IN THE VICINITY OF THE SOUTHERN COASTLINE WITH E-SE SURFACE
WINDS PERSISTING AND CONTINUED ADVECTION OF LOW-LEVEL MOISTURE.
THROUGH THE REST OF THE AFTERNOON AND EVENING HOURS...PEAK
HEATING AND INSTABILITY WILL OCCUR AND PROVIDE THE OPPORTUNITY
FOR SCATTERED SHOWERS AND TSTMS. OTHERWISE...LOOKING AHEAD OVER
THE NEXT FEW DAYS...THE SAN JUAN PUERTO RICO 14/1200 UTC UPPER
AIR SOUNDING INDICATED THE PRESENCE OF THE SAHARAN AIR LAYER
FROM 850 MB UP TO ROUGHLY 650 MB. THIS AIR LAYER WILL CONTINUE
TO IMPACT THE EASTERN AND CENTRAL CARIBBEAN THROUGH THE WEEKEND
HELPING TO LIMIT OVERALL COVERAGE OF CONVECTION WHILE ALSO
PROVIDING GENERALLY HAZY CONDITIONS.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED
NEAR 31N72W THAT INFLUENCES A LARGE PORTION OF THE SW NORTH ATLC
W OF 70W THIS AFTERNOON. THE RIDGING ALOFT CONTINUES TO SUPPORT
A SURFACE RIDGE OF HIGH PRESSURE EXTENDING FROM 28N70W WESTWARD
INTO THE NORTHERN GULF OF MEXICO ALONG 27N. MOSTLY FAIR SKIES
AND CONDITIONS ACCOMPANY THIS FEATURE AS WATER VAPOR IMAGERY
INDICATES AN AREA OF MODERATE DRY AIR AND SUBSIDENCE STRETCHING
FROM N OF THE BAHAMAS TO OFFSHORE OF THE CAROLINAS. S OF THE
BAHAMAS IN THE FLORIDA STRAITS...ISOLATED SHOWERS AND TSTMS ARE
OCCURRING AS MOISTURE FROM THE TROPICAL WAVE LOCATED ACROSS THE
WESTERN CARIBBEAN ADVECTS NORTHEAST. FARTHER EAST ACROSS THE
CENTRAL ATLC...AN UPPER LEVEL LOW IS CENTERED NEAR 28N63W AND
SUPPORTS A BROAD AREA OF WIDELY SCATTERED SHOWERS AND TSTMS FROM
23N-32N BETWEEN 59W-70W. OTHERWISE...FAIRLY BENIGN CONDITIONS
ARE NOTED ON SATELLITE IMAGERY E OF 55W AS A SURFACE RIDGE
ANCHORED BY A 1026 MB HIGH CENTERED NEAR 34N44W 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 58W.

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

$$
HUFFMAN


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