Tropical Weather Discussion
Issued by NWS

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000
AXNT20 KNHC 201800
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN JUL 20 2014

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 10N23W TO 17N22W MOVING W AT 10-15
KT. EXAMINING UPPER AIR TIME SECTION ANALYSES...THE WAVE PASSED
DAKAR SENEGAL AROUND 19/1800 UTC AND PAST GFS 700 MB AND 850 MB
RELATIVELY VORTICITY ANALYSIS FIELDS CONFIRM THE PASSAGE. AN
EARLY MORNING ASCAT PASS AROUND 20/1142 UTC INDICATES SLIGHT
CYCLONIC TURNING OF THE LOW-LEVEL WIND. CONVECTION REMAINS
LIMITED TO THE MONSOON TROUGH REGION WITH ONLY ISOLATED MODERATE
CONVECTION FROM 10N-13N BETWEEN 19W-24W.

TROPICAL WAVE EXTENDS FROM 10N35W TO 16N34W MOVING W AT 10-15
KT. THE WAVE REMAINS LARGELY EMBEDDED WITH IN THE ITCZ AXIS WITH
GLOBAL MODEL GUIDANCE INDICATING AN ELONGATED AREA OF 850 MB
RELATIVE VORTICITY FROM 08N-10N BETWEEN 30W-42W ON THE SOUTHERN
PERIPHERY OF A 700 MB EASTERLY JET MAXIMUM. CONVECTION IS
LIMITED DUE TO A SAHARAN AIR LAYER N OF 12N...HOWEVER WIDELY
SCATTERED MODERATE CONVECTION IS FROM 06N-12N BETWEEN 32W-43W.

TROPICAL WAVE EXTENDS FROM 09N62W TO 15N61W MOVING W AT 15-20
KT. AN EARLIER MORNING ASCAT PASS AROUND 20/1324 UTC INDICATES
SLIGHT CYCLONIC TURNING OF THE LOW-LEVEL WIND FIELD ACROSS
PORTIONS OF THE SE CARIBBEAN SEA AS WELL AS STRONGER NE TO E
WINDS W OF THE WINDWARD ISLANDS...LIKELY EMBEDDED WITHIN
CONVECTION AND ALSO ASSOCIATED WITH STRONG WINDS SURROUNDING THE
WAVE AXIS. ISOLATED MODERATE CONVECTION IS FROM 09N-14N BETWEEN
61W-65W.

TROPICAL WAVE EXTENDS FROM 11N76W TO 20N77W MOVING W AT 15 KT.
THE WAVE CONTINUES TO MOVE BENEATH UPPER LEVEL NORTHERLY FLOW
WHICH IS MAINTAINING A FAIRLY STABLE ENVIRONMENT IN THE VICINITY
OF THE WAVE. HOWEVER...ISOLATED MODERATE CONVECTION IS OCCURRING
FROM 16N-21N BETWEEN 74W-79W AND IS LIKELY DUE TO A MARGINALLY
DIFFLUENT MIDDLE TO UPPER LEVEL ENVIRONMENT OVER CUBA AND THE
WINDWARD PASSAGE REGION.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N17W TO
10N21W TO 10N27W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 10N27W TO 10N35W TO 05N48W. ASIDE FROM CONVECTION
ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE
CONVECTION IS FROM 06N-10N BETWEEN 23W-28W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL LONGWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY
OVER THE EASTERN CONUS WITH A SHORTWAVE TROUGH EVIDENT IN THE
BASE OF THE TROUGHING NEAR 31N87W. A WEAK 1015 MB SURFACE LOW IS
CENTERED ACROSS SW ALABAMA NEAR 31N87W WITH A STATIONARY FRONT
EXTENDING W-SW FROM THE LOW CENTER TO 29N92W TO THE TEXAS GULF
COAST NEAR 28N96W. MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING
DATA INDICATE SCATTERED TO NUMEROUS SHOWERS AND SCATTERED TSTMS
OCCURRING N OF 27N BETWEEN 84W-95W. FARTHER SOUTH...NORTHEASTERN
FLOW ALOFT PREVAILS ON THE SOUTHEASTERN PERIPHERY OF AN UPPER
LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER NORTHERN MEXICO
NEAR 29N102W. THIS IS PROVIDING OVERALL STABILITY TO THE
SOUTHERN GULF WATERS IN ADDITION TO A SURFACE RIDGE WITH AXIS
EXTENDING FROM THE SOUTHERN FLORIDA PENINSULA W-SW TO A 1018 MB
HIGH CENTERED ACROSS EAST-CENTRAL MEXICO NEAR 21N98W. THE RIDGE
IS EXPECTED TO GRADUALLY LIFT NORTHWARD THROUGH LATE TUESDAY AND
ANCHOR ALONG 27N/28N THURSDAY AND FRIDAY.

CARIBBEAN SEA...
UPPER LEVEL NORTH-NORTHEASTERLY FLOW IS OVER MUCH OF THE WESTERN
CARIBBEAN W OF AN UPPER LEVEL LOW CENTERED NEAR 15N73W WITH
TROUGH AXIS EXTENDING SOUTHWARD TO A BASE OVER NORTHERN COLOMBIA
NEAR 10N75W. MOSTLY FAIR SKIES PREVAIL ACROSS THE WESTERN
CARIBBEAN WITH THE EXCEPTION OF A FEW ISOLATED SHOWERS AND TSTMS
OCCURRING ACROSS WESTERN PANAMA AND COSTA RICA...INCLUDING THE
ADJACENT COASTAL WATERS W OF 82W...AND A FEW ISOLATED SHOWERS
AND TSTMS OCCURRING N OF 18N BETWEEN 74W-80W...INCLUDING THE
WINDWARD PASSAGE REGION AND EASTERN CUBA. OTHERWISE...THE ONLY
OTHER SIGNIFICANT FEATURE ACROSS THE CARIBBEAN IS THE PRESENCE
OF A TROPICAL WAVE ALONG 62W GENERATING ISOLATED SHOWERS AND
TSTMS S OF 14N BETWEEN 61W-66W. MODERATE TO FRESH TRADE CONTINUE
AND ARE EXPECTED TO PERSIST THROUGH MUCH OF THE WEEK AHEAD...
OCCASIONALLY WITH STRONGER WINDS 25 TO 30 KT OCCURRING WITHIN
CLOSE PROXIMITY TO THE COAST OF COLOMBIA AND NW VENEZUELA.

...HISPANIOLA...
CURRENTLY MOST OF THE ISLAND IS UNDER CLEAR SKIES...HOWEVER AS
THE AFTERNOON PROGRESSES AND PEAK HEATING AND INSTABILITY ARE
REACHED...ISOLATED SHOWERS AND TSTMS ARE EXPECTED ACROSS THE
ISLAND INTO THE EVENING HOURS. THE CONVECTION IS LIKELY TO BE
ENHANCED DUE TO AN UPPER LEVEL LOW NOTED ON WATER VAPOR IMAGERY
TO THE SOUTH NEAR 16N73W.

ATLANTIC OCEAN...
AN UPPER LEVEL LONGWAVE TROUGH IS OVER THE EASTERN CONUS WITH
THE BASE OF THE TROUGHING FOCUSED AROUND MID-LEVEL ENERGY
CENTERED NEAR 30N80W. WHILE THE SURFACE FRONT ASSOCIATED WITH
THE TROUGHING LIES INLAND ACROSS SOUTH CAROLINA...GEORGIA...AND
ALABAMA...SOUTHERLY FLOW ACROSS THE SW NORTH ATLC IS PROVIDING
FOR LOW-LEVEL MOISTURE CONVERGENCE AND THE GENERATING OF WIDELY
SCATTERED SHOWERS AND ISOLATED TSTMS FROM 21N-28N BETWEEN 74W-
79W. ISOLATED SHOWERS ARE ELSEWHERE N OF 28N BETWEEN 73W-81W.
FARTHER EAST...AN ELONGATED UPPER LEVEL LOW IS CENTERED NEAR
28N58W THAT SUPPORTS A SURFACE TROUGH ANALYZED FROM 25N59W TO
32N54W. ISOLATED SHOWERS ARE OCCURRING FROM 30N-32N BETWEEN 53W-
56W. THE REMAINDER OF THE CENTRAL AND EASTERN ATLC ARE UNDER THE
INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1028 MB HIGH CENTERED
SW OF THE AZORES NEAR 35N36W.

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

$$
HUFFMAN



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