[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 151747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 15 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 10N42W TO 21N40W MOVING W AT 15-20
KT. VISIBLE SATELLITE IMAGERY INDICATES BROAD LOW-LEVEL CYCLONIC
FLOW IN THE VICINITY OF THE WAVE AXIS WITH GLOBAL MODEL DATA
SHOWING THE WAVE COINCIDES WITH A BROAD 700 MB TROUGH AXIS N OF
10N BETWEEN 30W-40W. TOTAL PRECIPITABLE WATER IMAGERY ALSO SHOWS
A MAXIMUM COVERING THIS REGION. HOWEVER...A LACK OF SIGNFICANT
DEEP CONVECTION IS NOTED WITH THE WAVE DUE TO THE SAHARAN AIR
LAYER WHICH COVERS MUCH OF THE TROPICAL EASTERN ATLC E OF 60W.

TROPICAL WAVE EXTENDS FROM 05N52W TO 14N54W MOVING W AT 10-15
KT. THE WAVE REMAINS ON THE LEADING EDGE OF THE SAHARAN AIR
LAYER...PRIMARILY E OF 50W...AND EXHIBITS A NARROW AREA OF
MAXIMUM TOTAL PRECIPITABLE WATER FROM 04N-19N BETWEEN 52W-56W.
ISOLATED MODERATE CONVECTION IS FROM 05N-09N BETWEEN 51W-58W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N15W TO
07N27W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM
07N27W TO 08N32W TO 11N34W TO 11N42W TO 06N52W. WIDELY
SCATTTERED MODERATE CONVECTION IS FROM 02N-06N BETWEEN 09W-
13W...AND FROM 07N-11N BETWEEN 13W-16W. ISOLATED MODERATE
CONVECTION IS FROM 05N-08N BETWEEN 19W-37W.

...DISCUSSION...

GULF OF MEXICO...
A VIGOROUS MIDDLE TO UPPER LEVEL LOW IS LOCATED OVER THE
SOUTHERN PLAINS NEAR 34N99W THAT EXTENDS UPPER LEVEL TROUGHING
SOUTHEAST TO AN UPPER LEVEL LOW CENTERED OVER THE WESTERN GULF
NEAR 23N92W. WHILE A STATIONARY FRONT REMAINS ANALYZED OVER
INLAND EASTERN AND SOUTHERN TEXAS GENERATING SCATTERED SHOWERS
AND TSTMS N OF 26N W OF 91W OVER THE NW GULF...PLENTY OF LOW-
LEVEL MOISTURE CONTINUES TO ADVECT NORTHWARD OVER THE EASTERN
AND CENTRAL GULF. THIS LOW-LEVEL MOISTURE...ALONG WITH MAXIMIZED
MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS
AND TSTMS OVER THE CENTRAL GULF FROM 18N-29N BETWEEN 88W-92W...
WITH ISOLATED SHOWERS OCCURRING ELSEWHERE E OF 90W. AS THE
MIDDLE TO UPPER LEVEL DYNAMICS REMAIN THE DOMINATE FEATURE
ACROSS THE BASIN THIS AFTERNOON GENERATING THE ONGOING
CONVECTION...WEAK SURFACE RIDGING AND E-SE WINDS ARE EXPECTED TO
PERSIST THROUGH EARLY WEDNESDAY.

CARIBBEAN SEA...
WATER VAPOR IMAGERY INDICATES THE WESTERN CARIBBEAN W OF 78W IS
UNDER THE INFLUENCE OF AN ANTICYCLONIC CIRCULATION CENTERED OVER
THE NW CARIBBEAN NEAR 17N85W. PRIMARILY NORTHERLY FLOW DOMINATES
AND IS PROVIDING FOR AN OVERALL STABLE ATMOSPHERE...HOWEVER A
FEW ISOLATED SHOWERS ARE OCCURRING N OF 16N W OF 79W WITHIN THE
EASTERLIES AND MARGINAL LOW-LEVEL MOISTURE CONVERGENCE. THE
PRESENCE OF THE ANTICYCLONIC CIRCULATION IS ALSO PROVIDING
MIDDLE TO UPPER LEVEL DIFFLUENCE...STRONGEST OVER THE YUCATAN
PENINSULA. OTHERWISE...SOUTH-SOUTHWESTERLY FLOW ALOFT IS NOTED
ON WATER VAPOR IMAGERY BETWEEN A BROAD UPPER LEVEL LOW CENTERED
ACROSS THE SW NORTH ATLC AND AN UPPER LEVEL ANTICYCLONE CENTERED
EAST OF THE WINDWARD ISLANDS NEAR 12N58W. UPPER LEVEL CLOUDINESS
CONTINUES TO SWEEP EAST-NORTHEASTWARD E OF 70W WITH E-SE WINDS
NOTED AT THE SURFACE UNDER MOSTLY FAIR SKIES THIS AFTERNOON. THE
APPROACH OF A TROPICAL WAVE...CURRENTLY ALONG 54W...WILL USHER
IN INCREASED LOW-LEVEL MOISTURE...CLOUDINESS...AND ISOLATED
SHOWERS TUESDAY INTO WEDNESDAY.

HISPANIOLA...
CURRENTLY CONDITIONS ACROSS THE ISLAND REMAIN TRANQUIL...HOWEVER
AN UPPER LEVEL TROUGH AXIS EXTENDS FROM 26N70W TO 15N76W WHICH
ALONG WITH LOW-LEVEL MOISTURE CONVERGENCE AND OROGRAPHIC LIFT
WILL PROVIDE FOR SCATTERED AFTERNOON AND EARLY EVENING SHOWERS
AND TSTMS. MOST OF THE ACTIVITY AT THIS TIME IS LOCATED OFFSHORE
IN THE NORTHERN ADJACENT COASTAL WATERS...BUT WITH PEAK DAYTIME
HEATING AND INSTABILITY...CONVECTION WILL LIKELY INCREASE IN
COVERAGE THROUGH THE NEXT FEW HOURS. OTHERWISE...E-SE TRADES ARE
FORECAST TO PERSIST THROUGH THE WEEK AHEAD WITH THE GREATEST
PROBABILITY OF CONVECTION DURING THE AFTERNOON AND EVENING
HOURS.

ATLANTIC OCEAN...
A COMPLEX AND BROAD MIDDLE TO UPPER LEVEL LOW IS CENTERED IN THE
SW NORTH ATLC NEAR 26N71W THAT EXTENDS INFLUENCE FROM 17N-31N
BETWEEN 56W-83W. WHILE MOST OF THIS AREA IS EXPERIENCING
ISOLATED SHOWERS AND TSTMS...A MAJORITY OF THE ACTIVITY IS
FOCUSED IN THE VICINITY OF TWO SURFACE TROUGHS...ONE ANALYZED
FROM 20N62W TO 25N63W AND THE OTHER FARTHER WEST FROM 26N78W TO
31N80W. THE EASTERN-MOST SURFACE TROUGH...ALONG WITH MAXIMUM
MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS
AND TSTMS FROM 23N-30N BETWEEN 58W-68W. CONVECTION ASSOCIATED
WITH THE WESTERN-MOST SURFACE TROUGH REMAINS STRETCHED COVERING
AN AREA FROM EXTREME SOUTHERN GEORGIA...ALONG THE EASTERN
FLORIDA PENINSULA...TO THE NW BAHAMAS AND ACROSS AN AREA FROM
25N-28N BETWEEN 71W-77W. FARTHER EAST ACROSS THE REMAINDER OF
THE CENTRAL AND EASTERN ATLC...A MIDDLE TO UPPER LEVEL RIDGE IS
CENTERED NEAR 22N46W THAT SUPPORTS A SURFACE RIDGE ANCHORED BY A
1026 MB HIGH CENTERED NEAR 30N32W. AS MENTIONED IN THE TROPICAL
WAVE SECTION ABOVE...MUCH OF THE EASTERN AND CENTRAL TROPICAL
ATLC IS UNDER THE INFLUENCE OF A SAHARAN AIR LAYER E OF 50W.

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

$$
HUFFMAN


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