[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 311735
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI
FL 205 PM EDT SUN MAR 31 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
1415 UTC.

...THE ITCZ/THE MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS THROUGH THE COAST OF GUINEA-BISSAU
NEAR 12N16W INTO THE EASTERN TROPICAL ATLC ALONG 6N20W 3N22W.
THE ITCZ BEGINS NEAR 3N22W AND CONTINUES ALONG 1N30W 1N40W
1S46W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 2S-
2N BETWEEN 23W-30W...FROM EQ-4N BETWEEN 30W-42W...AND FROM 1N-3N
BETWEEN 46W-52W.

...DISCUSSION...

GULF OF MEXICO...
SOUTHEAST TO SOUTH FLOW COVERS THE GULF OF MEXICO AROUND A
SURFACE RIDGE ANCHORED IN THE WEST ATLC. CLEAR SKIES SPREAD
ACROSS A GOOD PORTION OF THE BASIN DUE TO DRY AIR ALOFT COVERING
THE SOUTHERN GULF AROUND THE BASE OF AN UPPER LEVEL TROUGH
EXTENDING DOWN FLORIDA ALONG 81W. HOWEVER...UPPER LEVEL MOISTURE
IS STREAMING AROUND AN UPPER LEVEL RIDGE MOVING INTO THE AREA
ALONG 97W. AN AREA OF SHOWERS/THUNDERSTORMS IS IN THE NE CORNER
FROM 28N-29N BETWEEN 83W-87W LIKELY DUE TO WIND SPEED
CONVERGENCE.  A RECENT ASCAT PASS INDICATES SOUTHERLY WINDS UP
TO 20 KT JUST SOUTH OF THE AREA OF ACTIVITY WITH 10-15 KT WINDS
TO THE NORTH. WINDS UP TO 15 KT COVER MUCH OF THE EASTERN GULF
WITH 10-15 KT WINDS ACROSS THE WESTERN GULF. THE RIDGE WILL
CONTINUE TO MOVE EAST ALLOWING RETURN FLOW TO INCREASE ACROSS
THE GULF MID-WEEK BEFORE A COLD FRONT AND SURFACE LOW SWEEP
THROUGH THE BASIN THROUGHOUT THE SECOND HALF OF THE WEEK.

CARIBBEAN SEA...
DRY AIR ALOFT AROUND THE BASE OF THE UPPER TROUGH EXTENDING DOWN
FLORIDA AND INTO THE NW CARIBBEAN IS PROVIDING FAIR CONDITIONS
ACROSS THE WESTERN CARIBBEAN. MODERATE DRY AIR ALSO COVERS THE
CENTRAL AND EASTERN CARIBBEAN AROUND A BROAD UPPER LEVEL RIDGE
COVERING MUCH OF THE CENTRAL AND EASTERN ATLC. THE DRY AIR IS
MAINTAINING FAIR CONDITIONS ACROSS THE CENTRAL AND EASTERN AREAS
EXCEPT FOR SOME MOISTURE REMAINING ACROSS THE NORTHERN ISLANDS.
THIS MOISTURE REMAINS FROM AN OLD FRONTAL BOUNDARY/SHEAR AXIS
THAT HAS NOW DISSIPATED.  SCATTERED SHOWERS ARE FROM 16N-19N
BETWEEN 63W-70W INCLUDING AREAS OF PUERTO RICO AND EASTERN
HISPANIOLA. STRONG TRADEWIND FLOW OF 20-25 KT IS PRESENT ACROSS
A LARGE AREA OF THE BASIN DUE TO THE INCREASED PRESSURE GRADIENT
BETWEEN HIGH PRESSURE TO THE NORTH AND LOW PRESSURE OVER SOUTH
AMERICA. WINDS REACH 30 KT OFF THE COAST OF COLOMBIA. MOISTURE
WILL REMAIN OVER THE NORTHERN CARIBBEAN FOR AT LEAST THE NEXT
DAY BEFORE LIFTING NORTH. LITTLE CHANGE IS EXPECTED ELSEWHERE
ACROSS THE BASIN.

ATLANTIC OCEAN... SURFACE RIDGING COVERS THE WEST ATLC INTO THE
CENTRAL ATLC ANCHORED BY A 1026 MB HIGH NEAR 30N68W. THE RIDGE
IS PROVIDING MOSTLY FAIR WEATHER ACROSS THIS AREA. THE RIDGE IS
SUPPORTED BY AN UPPER LEVEL RIDGE ALONG 69W. A WEAK UPPER TROUGH
IS TO THE EAST SUPPORTING A SURFACE TROUGH ALONG 32N55W 29N59W
27N63W. THE SURFACE TROUGH EXTENDS INTO THE SURFACE RIDGE.
ISOLATED SHOWERS ARE WITHIN 150 NM EAST OF THE AXIS. A BROAD
UPPER TROUGH NORTH OF THE DISCUSSION AREA SUPPORTS A WEAK COLD
FRONT THAT STRETCHES ACROSS THE BASIN FROM THE NE SECTION NEAR
32N22W ALL THE WAY TO THE NE CARIBBEAN ALONG 24N36W 20N50W
BECOMING STATIONARY TO 19N63W. ISOLATED SHOWERS ARE WITHIN 90 NM
EAST OR SOUTH OF THE AXIS. A VERY BROAD UPPER RIDGE COVERS THE
REMAINDER OF THE TROPICAL ATLC CENTERED NEAR 18N26W. A STRONG
UPPER LEVEL JET IS ALONG THE NORTHERN PERIPHERY OF THE RIDGE
REACHING UP TO 150 KT SOUTH OF THE AZORES ISLANDS.

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

$$
WALTON


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