[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 101737
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI MAY 10 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.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA-BISSAU NEAR
12N16W TO 5N23W. THEN...THE INTERTROPICAL CONVERGENCE ZONE AXIS
CONTINUES FROM 5N23W TO 2N40W TO THE COAST OF BRAZIL AT EQ50W.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED FROM
2N TO THE COAST OF AFRICA BETWEEN THE PRIME MERIDIAN AND 12N.
SCATTERED MODERATE CONVECTION IS FROM 3N TO 6N BETWEEN 22W AND
27W AND FROM 4N TO 6N W OF 35W.

...DISCUSSION...

GULF OF MEXICO...

A 1022 MB HIGH PRES LOCATED NEAR 30N73W EXTENDS A RIDGE E TO W
ACROSS THE NORTHERN GULF WATERS PRODUCING A MODERATE TO FRESH
SOUTHERLY WIND FLOW ACROSS THE REGION. LOWER PRESSURES ARE NOTED
OVER THE WESTERN GULF AHEAD OF THE NEXT COLD FRONT FORECAST TO
MOVE OFF THE LOUISIANA AND TEXAS COAST EARLY SAT. THE FRONT WILL
REACH FROM THE WESTERN FLORIDA PANHANDLE TO 21N97W ON SAT
NIGHT...AND WEAKEN FROM THE FLORIDA BIG BEND TO THE BAY OF
CAMPECHE ON SUN. A BAND OF SHOWERS AND THUNDERSTORMS WILL LIKELY
BE ASSOCIATED WITH THE FRONT. CURRENTLY...SHOWERS AND TSTMS ARE
DEVELOPING AHEAD OF THE FRONT OVER SE LOUISIANA AND ALONG THE
COST OF TEXAS IN ASSOCIATION WITH A MOIST ONSHORE FLOW OVER THE
AREA. ALOFT... AN UPPER LEVEL RIDGE...CENTERED ON AN ANTICYCLONE
NEAR THE GULF OF TEHUANTEPEC...COVERS THE GULF WITH AXIS NEAR
90W. UPPER LEVEL DIFFLUENCE IS HELPING TO INDUCE THE CONVECTION
OVER TEXAS AND LOUISIANA. MID/UPPER LEVEL MOISTURE DOMINATES
MUCH OF THE REGION.

CARIBBEAN SEA...

AN UPPER LEVEL TROUGH CONTINUES TO BE THE MAIN WEATHER PLAYER
ACROSS THE REGION. THE TROUGH HAS MOVED E OF FLORIDA AND THE
AXIS IS NEAR 73W/74W ACROSS THE SW N ATLC AND THE CARIBBEAN SEA.
DRY AIR ALOFT IS ACROSS THE WESTERN CARIBBEAN ON THE WEST SIDE
OF THE TROUGH...BUT ABUNDANT MID/UPPER LEVEL MOISTURE IS NOTED
AHEAD OF THE TROUGH OVER THE EASTERN CARIBBEAN UNDER THE
INFLUENCE OF A SW WIND FLOW ALOFT. THIS UPPER LEVEL TROUGH
CONTINUES TO SUPPORT A SURFACE TROUGH THAT NOW EXTENDS FROM
26N69W TO DOMINICAN REPUBLIC NEAR 19N70W. THE STRONGEST
CONVECTION ASSOCIATED WITH THIS FEATURE IS N OF HISPANIOLA. SOME
DRY AIR IS MAKING ITS WAY TOWARD HISPANIOLA...RESULTING IS LESS
SHOWER AND TSTM ACTIVITY THAN THE PREVIOUS DAYS WHEN THE TROUGH
AXIS WAS WEST OF THE ISLAND. COMPUTER MODEL SHOWS MOISTURE
ASSOCIATED WITH THIS TROUGH AFFECTING PUERTO RICO AND US/UK
VIRGIN ISLANDS ON SAT. CONVECTION CONTINUES TO FLARE UP OVER THE
SW CARIBBEAN IN ASSOCIATION WITH THE COLOMBIAN/PANAMANIAN LOW.
THERE IS A CLUSTER OF MODERATE TO STRONG CONVECTION S OF 10N E
OF 78W TO THE COAST OF COLOMBIA. ANOTHER CLUSTER OF SIMILAR
CONVECTION IS ALSO NOTED S OF 10N W OF 80W. THE MIMIC-TPW
ANIMATION SHOWS A GOOD SURGE OF MOISTENED AIR OVER THE SW
CARIBBEAN. SCATTEROMETER DATA SHOW FRESH TO STRONG TRADE WINDS
ACROSS THE SOUTH CENTRAL CARIBBEAN WHILE MODERATE TO FRESH
TRADES PREVAIL ELSEWHERE. THIS REGIMEN WILL PERSIST OVER THE
NEXT SEVERAL DAYS AS HIGH PRES REMAINS STRONG NE OF AREA.
MOISTURE WITH A SHEAR AXIS OVER THE NE CARIBBEAN IS EXPECTED TO
SHIFT SOUTH ACROSS THE LESSER ANTILLES SAT. NE WINDS OF 15 TO 20
KT ARE STILL NOTED N OF THE SHEAR AXIS.

ATLANTIC OCEAN...

AN UPPER LEVEL TROUGH EXTENDS FROM 31N72W TO THE SE BAHAMAS AND
IS SUPPORTING THE AFOREMENTIONED SURFACE TROUGH THAT GOES FROM
26N69W TO DOMINICAN REPUBLIC. A LARGE AREA OF SHOWERS AND
THUNDERSTORMS IS AHEAD OF THE TROUGH COVERING FROM 20N-30N
BETWEEN 65W-70W. BROAD SURFACE RIDGING COVERS THE REMAINDER OF
THE WESTERN AND CENTRAL ATLC SUPPORTED BY AN UPPER LEVEL RIDGE
ALONG 60W. BROAD UPPER TROUGHING COVERS THE EASTERN ATLC WITH
AXIS NEAR 35W. THE UPPER TROUGH SUPPORTS A WEAK 1016 MB SURFACE
LOW NEAR 31N30W. A SURFACE TROUGH EXTENDS FROM THE LOW CENTER TO
NEAR 24N33W. NO SHOWER ACTIVITY IS NEAR THE TROUGH. A SECOND
WEAK LOW PRES IS NEAR 31N43W. VISIBLE SATELLITE IMAGERY SHOWS A
SWIRL OF LOW CLOUDS ASSOCIATED WITH THE LOW CENTER. SCATTERED
SHOWERS ARE IN BANDS TO THE NE AND SE OF LOW CENTER. AN AREA OF
SAHARAN DUST IS NOTED ON VIS SATELLITE IMAGERY REACHING 35W...
AND IS CONFIRMED BY THE SAHARAN AIR LAYER TRACKING PRODUCT FROM
UW-CIMSS. MOISTURE NEAR THE SHEAR AXIS THAT EXTENDS ALONG 20N36W
TO 16N50W TO 16N50W TO 19N67W IS DIMINISHING.

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

AT THE REQUEST OF METEO-FRANCE AND THE METEOROLOGICAL SERVICES OF
HAITI AND THE DOMINICAN REPUBLIC...THE TROPICAL ANALYSIS AND
FORECAST BRANCH (TAFB) WILL BEGIN PROVIDING...ON A TEMPORARY
BASIS...A SEPARATE DETAILED SECTION WITHIN THE ATLANTIC TROPICAL
WEATHER DISCUSSION (TWDAT). IT WILL COVER BOTH HAITI AND THE
DOMINICAN REPUBLIC DUE TO THE SHARED GEOGRAPHY OF BOTH COUNTRIES
ON THE ISLAND OF HISPANIOLA.

THE SECTION BEGINS ON MAY 15 2013 AT 1800 UTC...2 PM EDT. IT
WILL PROVIDE GUIDANCE FOR SIGNIFICANT WEATHER EVENTS THAT ARE
EXPECTED TO IMPACT THE REGION THROUGH 48 HOURS...WITH THE FOCUS
ON ASSESSING THE POTENTIAL FOR HEAVY RAINFALL.

$$
GR

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