[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031758
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED JUL 03 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 10N22W TO 20N20W MOVING W-NW AT 10-15
KT. THE WAVE REMAINS EMBEDDED WITHIN A POLEWARD SURGE OF
MODERATE TO DEEP MOISTURE AS SHOWN ON TOTAL PRECIPITABLE WATER
IMAGERY WITH GREATEST DEFINITION OF THE WAVE AXIS NOTED ON
GLOBAL MODEL DATA AT THE 700 MB LEVEL. SATELLITE WINDS ALSO
CONFIRM THE PRESENCE OF THE WAVE NEAR THIS LOCATION. CONVECTION
REMAINS CONFINED TO AN AREA SOUTH OF THE AXIS WITH WIDELY
SCATTERED MODERATE CONVECTION FROM 06N-10N BETWEEN 19W-26W AND
LIKELY ENHANCED DUE TO CLOSE PROXIMITY OF THE MONSOON TROUGH
AXIS AND INTERTROPICAL CONVERGENCE ZONE AXIS.

TROPICAL WAVE EXTENDS FROM 06N42W TO 14N36W MOVING W-NW AT 15-20
KT. SATELLITE PRESENTATION SHOWS THE WAVE AND ASSOCIATED SHOWER
AND TSTM ACTIVITY COINCIDES WITH A BROAD MID-LEVEL 700 MB TROUGH
S OF 20N BETWEEN 35W-46W. NO SIGNIFICANT DEEP CONVECTION IS
ASSOCIATED WITH THE WAVE AT THIS TIME DUE TO THE PRESENCE OF THE
SAHARAN AIR LAYER AND DUST ON THE SURROUNDING NORTHERN PERIPHERY
OF THE WAVE AXIS.

TROPICAL WAVE EXTENDS FROM 15N62W TO 22N60W MOVING W AT 20 KT.
THE WAVE REMAINS ASSOCIATED WITH A WEAK MID-LEVEL TROUGH
PROGRESSING ACROSS THE NE CARIBBEAN SEA AND PORTIONS OF THE SW
NORTH ATLC. NO SIGNIFICANT CONVECTION IS NOTED WITH THE WAVE AT
THIS TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO
09N21W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
09N21W TO 08N28W TO 12N36W...THEN RESUMES WEST OF THE TROPICAL
WAVE NEAR 06N44W TO THE EQUATOR NEAR 49W. ISOLATED MODERATE
CONVECTION IS FROM 05N-07N BETWEEN 44W-49W.

...DISCUSSION...

GULF OF MEXICO...
AN RELATIVELY AMPLIFIED UPPER LEVEL PATTERN DOMINATES OVER THE
CONUS THIS AFTERNOON WITH A MIDDLE TO UPPER LEVEL LOW CENTERED
OVER MISSOURI THAT IS PROVIDING MUCH OF THE GULF WITH MOIST
SOUTHWESTERLY FLOW ALOFT. THE TROUGHING SUPPORTS A 1013 MB LOW
CENTERED NEAR 27N91W WHICH IS ALONG A SURFACE TROUGH AXIS
EXTENDING FROM SOUTHERN ALABAMA NEAR MOBILE BAY TO THE LOW
CENTER THEN SOUTHWEST TO 24N95W. MOST OF THE ACTIVE WEATHER IS
LOCATED WEST OF THIS BOUNDARY IN MAXIMIZED LOW-LEVEL MOISTURE
CONVERGENCE AND MID-LEVEL DIFFLUENCE. SCATTERED SHOWERS AND
TSTMS ARE OCCURRING BETWEEN THE WESTERN COAST OF THE FLORIDA
PENINSULA ALONG 81W TO 90W...ALSO INCLUDING AN AREA WITHIN 120
NM OF THE YUCATAN PENINSULA COAST. THE LOW IS FORECAST TO DRIFT
NORTHEASTWARD AND GRADUALLY DISSIPATE INLAND AS THE ASSOCIATED
SURFACE TROUGHING DRIFTS WESTWARD THROUGH LATE FRIDAY.

CARIBBEAN SEA...
THE WESTERN CARIBBEAN SEA IS UNDER THE INFLUENCE OF AN UPPER
LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE GULF OF
HONDURAS NEAR 18N88W WHICH IS PROVIDING PRIMARILY NORTHERLY
FLOW. DIFFLUENCE IS MAXIMIZED BENEATH THIS UPPER LEVEL FEATURE
WITH SCATTERED SHOWERS AND TSTMS OCCURRING N OF 16N W OF 82W.
FARTHER SOUTH...THE MONSOON TROUGH IS ANALYZED ALONG 09N/10N AND
IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND TSTMS WITHIN 120 NM
NORTH OF THE AXIS BETWEEN 79W-85W...INCLUDING INLAND PORTIONS OF
COSTA RICA AND SOUTHERN NICARAGUA. EAST OF 70W...WATER VAPOR
IMAGERY INDICATES DRIER AIR IS PROGRESSING WESTWARD FROM THE
TROPICAL ATLC OVER PORTIONS OF THE EASTERN CARIBBEAN AND
VENEZUELA WITH ONLY A FEW ISOLATED LOW-TOPPED SHOWERS OCCURRING
BETWEEN 65W-78W...INCLUDING PUERTO RICO AND HISPANIOLA.
FINALLY...A WEAK TROPICAL WAVE ALONG 61W IS FORECAST TO SKIRT
THE NE CARIBBEAN AND PROVIDE FOCUS FOR ISOLATED SHOWER ACTIVITY
THE NEXT COUPLE DAYS AS IT TRACKS WEST.

HISPANIOLA...
AN UPPER LEVEL LOW IS CENTERED N-NW OF THE ISLAND NEAR 23N72W
AND EXTENDS AN UPPER LEVEL TROUGH AXIS S-SE TO 16N69W. EAST-
SOUTHEASTERLY TRADES CONTINUE TO ADVECT LOW-LEVEL MOISTURE AND
ALONG WITH MID-LEVEL LIFTING DYNAMICS...THE ATMOSPHERE SUPPORTS
ISOLATED SHOWERS CURRENTLY. AS THE AFTERNOON AND EVENING
PROGRESS...AND DAYTIME HEATING PEAKS WITH MAXIMUM INSTABILITY...
AREAL COVERAGE WITH CONVECTION IS EXPECTED TO INCREASE WITH
SCATTERED SHOWERS AND TSTMS. THE ACTIVITY SHOULD DIMINISH BY
LATE EVENING.

ATLANTIC OCEAN...
AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NEAR
23N72W THAT IS PROVIDING PORTIONS OF THE SW NORTH ATLC WITH
WIDELY SCATTERED SHOWERS FROM 16N-26N BETWEEN 67W-73W. THIS
UPPER LEVEL FEATURE IS LOCATED ABOVE A SURFACE RIDGE ANCHORED BY
A 1030 MB HIGH CENTERED NORTH OF BERMUDA NEAR 35N65W. THE RIDGE
IS FORECAST TO MOVE VERY LITTLE THROUGH LATE SATURDAY WITH A
TROPICAL WAVE ALONG 61W TRACKING WESTWARD ON THE SOUTHERN
PERIPHERY OF THE RIDGE ACROSS THE NE CARIBBEAN SEA AND GREATER
ANTILLES. OTHERWISE...THE REMAINDER OF THE CENTRAL AND EASTERN
ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A
1028 MB HIGH CENTERED SOUTH OF THE AZORES NEAR 35N30W.

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

$$
HUFFMAN


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