Tropical Weather Discussion
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000
AXNT20 KNHC 182355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS OVER THE CAPE VERDE ISLANDS WITH AXIS EXTENDING
FROM 17N24W TO 7N24W MOVING W 10 TO 15 KT OVER THE PAST 24
HOURS. THE SOUTHERN PORTION OF THE WAVE IS EMBEDDED IN THE
MONSOON TROUGH WHICH IS SUPPORTING SCATTERED MODERATE TO STRONG
CONVECTION FROM 6N-9N BETWEEN 26W-30W. ELSEWHERE...DRY SAHARAN
AIR INTERACTING WITH THE WAVE HAS SUPPRESSED CONVECTIVE
DEVELOPMENT.

TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AXIS EXTENDING FROM
14N44W TO 7N46W MOVING W AT 15 KT OVER THE PAST 24 HOURS. THE
LOW-AMPLITUDE WAVE IS EMBEDDED IN THE MOIST ENVIRONMENT OF THE
ITCZ/MONSOON TROUGH. CURRENTLY ONLY ISOLATED MODERATE CONVECTION
WAS NOTED FROM 8N-11N BETWEEN 42W-50W.

TROPICAL WAVE IS MOVING ACROSS THE WINDWARD ISLANDS. ITS AXIS
EXTENDS FROM 16N60W TO 7N63W AND IS MOVING W AT 15-20 KT OVER
THE PAST 24 HOURS. A DEEP LAYER MOIST ENVIRONMENT IS ASSOCIATED
WITH THE WAVE. A 1312 UTC ASCAT PASS CAPTURED THE WAVE AXIS
E OF THE WINDWARD ISLANDS EARLIER TODAY.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLC
ON THE COAST OF SENEGAL NEAR 13N17W AND CONTINUES ALONG 9N25W TO
9N39W. THE ITCZ BEGINS NEAR 9N39W AND CONTINUES TO 7N55W TO NEAR
TRINIDAD AT 10N61W. IN ADDITION TO THE CONVECTION ASSOCIATED
WITH THE WAVES...SCATTERED MODERATE CONVECTION IS FROM 6N-10N
BETWEEN 30W-37W.

...DISCUSSION...

GULF OF MEXICO...

A VERY SHARP MID-TO UPPER LEVEL TROUGH FOR JULY EXTENDS FROM THE
GREAT LAKES SW TO A BASE OVER EAST TEXAS/LOUISIANA AND SUPPORTS
A STATIONARY FRONT ALONG THE GULF COAST FROM THE FLORIDA
PANHANDLE TO TEXAS. A PRE-FRONTAL TROUGH EXTENDED FROM NEAR NEW
ORLEANS TO LAFAYETTE LOUISIANA...BRIEFLY INTO THE GULF OF MEXICO
AND TO THE TEXAS COAST JUST S OF GALVESTON THEN CONTINUES INTO
NE MEXICO TO A 1010 MB LOW OVER THE HIGH TERRAIN. AN UPPER LEVEL
ANTICYCLONE DOMINATED THE PATTERN OVER THE GULF AND WAS ORIENTED
E TO W ALONG 27N/28N. SATELLITE DERIVED WINDS INDICATED STRONG
EASTERLIES OF 40-50 KT ON THE SOUTHSIDE OF THE ANTICYCLONE OVER
THE SOUTHERN GULF AND BAY OF CAMPECHE. A LINE OF STRONG
THUNDERSTORMS AND SQUALL LINE EXTENDED FROM PENSACOLA FLORIDA TO
110 NM SSE OF NEW ORLEANS. ADDITIONAL STRONG ACTIVITY WAS NOTED
ABOUT 75 NM S OF LAFAYETTE LOUISIANA. SCATTERED SHOWERS ISOLATED
THUNDERSTORMS WERE NOTED ELSEWHERE N OF 27N W OF 90W AND WERE
ENHANCED BY DIFFLUENCE ALOFT. OTHERWISE...SURFACE WINDS ARE
GENERALLY LIGHT AND VARIABLE OVER THE GULF BECOMING MORE
SOUTHERLY AT 10-15 KT W OF 90W. SURFACE RIDGING AND RETURN FLOW
WILL DOMINATE ACROSS THE REGION FOR THE NEXT TWO DAYS.

CARIBBEAN SEA...

AN UPPER LEVEL TROUGH/SHEAR AXIS BISECTS THE CARIBBEAN AND
EXTENDS FROM THE MONA PASSAGE THROUGH 15N75W TO A FAIRLY
EXTENSIVE CYCLONIC CIRCULATION OVER HONDURAS. A TROPICAL WAVE IS
MOVING ACROSS THE WINDWARD ISLANDS INTO THE EXTREME E CARIBBEAN
SEA. CONVECTIVE ACTIVITY WITH THE WAVE HAS DECREASED
SIGNIFICANTLY OVER THE PAST SEVERAL HOURS WITH ONLY WIDELY
SCATTERED SHOWERS NEAR GRENADA AND THE ENTRANCE TO THE CARIBBEAN
SEA. THE WAVE WAS EMBEDDED WITHIN AN AREA OF ANTICYCLONIC
SOUTHWESTERLY FLOW ALOFT TO THE SE OF THE UPPER TROUGH. HIGHER
SURFACE PRESSURES ACROSS THE NORTHERN CARIBBEAN AND LOWER
PRESSURES OVER COLOMBIA CONTINUE TO SUPPORT A TIGHT PRESSURE
GRADIENT OVER THE SOUTHERN-CENTRAL PORTION OF THE BASIN. A 1406
UTC ASCAT PASS CAPTURED AN AREA OF 25 TO LOCALLY 30 KT WINDS
OVER THE CARIBBEAN FROM 11N TO 15N BETWEEN 72W AND 77W. THE WAVE
IS FORECAST TO PASS S OF HISPANIOLA SAT NIGHT AND EARLY SUN. THE
NEXT TROPICAL WAVE IS EXPECTED TO ENTER THE EASTERN PORTION OF
THE BASIN BY MON.

...HISPANIOLA...

THE PROXIMITY OF THE UPPER LEVEL TROUGH/SHEAR AXIS TO HISPANIOLA
HAS RESULTED IN ENOUGH DESTABILIZATION TO PRODUCE MORE
WIDESPREAD CONVECTION OVER THE INTERIOR OF THE ISLAND THIS
AFTERNOON AND EVENING THAN IN PREVIOUS DAYS. A TROPICAL WAVE
OVER THE WINDWARD ISLANDS IS EXPECTED TO MOVE S OF THE ISLAND
SAT NIGHT AND SUN AND WITH THE PRESENCE OF THE UPPER LEVEL
TROUGH ANOTHER ROUND OF WIDESPREAD SHOWERS/THUNDERSTORMS ARE
EXPECTED OVER THE ISLAND SAT AFTERNOON AND THROUGH THE WEEKEND.

ATLANTIC OCEAN...

A MID-LEVEL SHORT-WAVE INVERTED TROUGH IS OVER THE SW N ATLC
WITH UPPER-LEVEL DIVERGENCE TO THE S OF THE TROUGH OVER THE
BAHAMAS. THIS ENVIRONMENT ALONG WITH ABUNDANT MOISTURE IN THE
REGION CONTINUE TO SUPPORT SCATTERED SHOWERS AND ISOLATED TSTMS
N OF 22N BETWEEN 70W-76W. FARTHER EAST...A MID-UPPER LEVEL LOW
CENTERED NEAR 27N52W WAS RACING WESTWARD AT 20-25 KT. THIS LOW
WAS SUPPORTING SCATTERED SHOWERS WITHIN 180 NM W OF A SURFACE
TROUGH EXTENDING FROM 32N48W TO 26N51W. FURTHER EAST...A DYING
COLD FRONT ENTERED THE AREA NEAR 32N25W AND EXTENDED TO 28N35W.
OTHERWISE...THE CENTRAL AND EASTERN ATLC ARE UNDER THE INFLUENCE
OF A SURFACE RIDGE ANCHORED BY A 1031 MB HIGH CENTERED NEAR
37N50W.

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

$$
COBB


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