[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 181042
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED APR 18 2012

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 10N14W TO 3N19W WHERE THE ITCZ AXIS CONTINUES S OF THE
EQUATOR NEAR 27W. CLUSTERS OF SCATTERED MODERATE/STRONG
CONVECTION ARE FROM 7N TO JUST S OF THE EQUATOR BETWEEN 10W-15W
AND FROM 4N TO S OF THE EQUATOR BETWEEN 15W-33W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS FROM 6N-8N BETWEEN
51W-54W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH DIPS S ACROSS THE MISSISSIPPI VALLEY INTO THE N
GULF WITH A SHORTWAVE UPPER TROUGH ALONG 88W SUPPORTING A COLD
FRONT AT 18/0900 UTC EXTENDS INTO THE GULF ACROSS SW GEORGIA AND
THE W FLORIDA PANHANDLE TO A 1013 MB LOW JUST S OF MOBILE
ALABAMA CONTINUING AS A STATIONARY FRONT ALONG 26N89W 24N91W TO
THE COAST OF S MEXICO NEAR 18N92W. CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 200/250 NM E OF THE
FRONT. A BROAD UPPER RIDGE EXTENDS FROM THE W CARIBBEAN ACROSS
THE W TIP OF CUBA INTO THE FAR E GULF ACROSS NE FLORIDA INTO THE
FAR W ATLC. WEAK SURFACE RIDGE REMAINS ANCHORED IN THE W ATLC
EXTENDING INTO THE E GULF TO THE FRONT. STRONG SUBSIDENCE AND
DRY STABLE AIR ARE DOMINATING THE GULF W OF THE FRONT AS A
SURFACE RIDGE BUILD S OVER THE W GULF ANCHORED BY A 1023 MB HIGH
OVER E TEXAS AND GIVING THE AREA W OF THE FRONT MOSTLY CLEAR
SKIES THIS MORNING. FRONT WILL REMAIN NEAR STATIONARY THEN MOVE
N THU AS THE WEAK ATLC SURFACE RIDGE. SECOND STRONGER COLD FRONT
WILL ENTER NW GULF FRI NIGHT AND REACH FROM A SURFACE LOW NEAR
SE LOUISIANA TO W BAY OF CAMPECHE EARLY SAT. STRONG TO NEAR GALE
FORCE WINDS BEHIND THE FRONT BEFORE IT EXITS THE BASIN LATE SUN.

CARIBBEAN SEA...
THE UPPER RIDGE OVER THE E GULF OF MEXICO IS ANCHORED OVER E
PANAMA COVERING THE W CARIBBEAN WITH A WEAK UPPER TROUGH OVER
THE E CARIBBEAN WITH THE AXIS ALONG 63W. REMNANT LOW LEVEL
MOISTURE WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS ARE WITHIN 90/120 NM OF A LINE FROM 16N60W ACROSS
THE LEEWARD ISLANDS TO 11N80W. THE TRADE WINDS CONTINUE TO BANK
LOW CLOUDS WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS INLAND
AND WITHIN 90 NM ALONG THE COAST FROM CENTRAL PANAMA TO S
NICARAGUA. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER
DEVELOPING INLAND OVER CENTRAL AMERICA AND ARE SPREADING INTO
THE GULF OF HONDURAS S OF 19N W OF 85W. A COLD FRONT WILL
APPROACH YUCATAN CHANNEL LATE SAT MOVING THROUGH THE NW
CARIBBEAN THROUGH MON.

ATLANTIC OCEAN...
THE UPPER RIDGE OVER THE E GULF OF MEXICO AND THE W CARIBBEAN
COVERS THE W ATLC WITH A WEAK SURFACE RIDGE REMAINING OVER THE W
ATLC W OF 70W AND ANCHORED BY A 1022 MB HIGH NEAR 29N75W. A
BROAD UPPER TROUGH REMAINS OVER THE CENTRAL ATLC N OF 20N
BETWEEN 45W-70W SUPPORTING A COLD FRONT THAT ENTERS THE AREA
NEAR 32N53W ALONG 27N55W TO 25N62W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE WITHIN 60/75 NM ALONG THE FRONT N OF 27N WITH
POSSIBLE ISOLATED SHOWERS WITHIN 60 NM EITHER SIDE OF THE
REMAINDER OF THE FRONT. THE STATIONARY FRONT ENTERS THE
E/CENTRAL ATLC NEAR 32N44W TO 28N44W WHERE IT DISSIPATES TO
22N47W. THE SURFACE TROUGH IS RETROGRADING NW EXTENDING FROM
26N48W TO 20N55W. SCATTERED SHOWERS ARE WITHIN 75 NM EITHER SIDE
OF THE SURFACE TROUGH. A BROAD E/W UPPER RIDGE DOMINATES THE
TROPICAL ATLC. A LARGE SURFACE RIDGE DOMINATES THE E ATLC N OF
10N E OF 40W ANCHORED BY A 1033 MB HIGH JUST W OF THE AZORES.
THIS IS LEAVING THE REMAINDER OF THE ATLC WITH FAIR WEATHER THIS
MORNING. W ATLC SURFACE RIDGE WILL SHIFT NE AND WEAKEN THROUGH
FRI. A STRONG FRONT WILL MOVE OFF FLORIDA LATE SUN MOVING NE
THROUGH MON CLIPPING THE W ATLC DISCUSSION AREA. THE CENTRAL
ATLC COLD FRONT WILL MOVE SLOWLY E AS THE SURFACE LOW MOVES S
INTO THE DISCUSSION AREA ON WED. THE FRONT WILL THEN DISSIPATE
WED NIGHT THROUGH FRI BEFORE THE LOW MOVES NE OUT OF THE AREA.

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

$$
PAW






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