[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 152342
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT FRI MAR 15 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 AFRICAN COAST NEAR 07N12W TO
05N15W TO 05N19W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS 05N19W TO 05N25W TO THE EQUATOR NEAR 44W. ISOLATED
MODERATE CONVECTION IS S OF 05N BETWEEN 20W-38W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES FAIRLY DRY AIR ALOFT OVER THE GULF
DUE TO CONFLUENT UPPER LEVEL FLOW ALONG 28N AND MIDDLE LEVEL
NORTHWESTERLY FLOW. THIS OVERALL ATMOSPHERIC REGIME ALOFT IS
CONTINUING TO SUPPORT A BROAD SURFACE RIDGE ANCHORED BY A 1027
MB HIGH CENTERED IN THE NE GULF NEAR 29N84W AND A LOCALIZED 1026
MB HIGH CENTERED ACROSS EAST-CENTRAL MEXICO NEAR 22N98W. LIGHT
ANTICYCLONIC SURFACE WINDS ARE FOUND GENERALLY N OF 26N E OF 91W
WITH THE REMAINDER OF THE GULF UNDER EAST TO SOUTHEAST WINDS IN
THE RANGE OF 10 TO 20 KT. THE RIDGE IS FORECAST TO SLIDE
EASTWARD THROUGH THE WEEKEND WITH SOUTHERLY RETURN FLOW BECOMING
DOMINATE AFTER EARLY SATURDAY. WINDS WILL REMAIN SOUTHERLY
THROUGH LATE MONDAY AS AN AREA OF LOW PRESSURE DEVELOPS OVER THE
SOUTHERN PLAINS. BY EARLY TUESDAY...THE ASSOCIATED COLD FRONT
WILL BE POISED TO EMERGE OFF THE TEXAS AND LOUISIANA COAST AND
INTO PORTIONS OF THE NORTHERN GULF WATERS.

CARIBBEAN SEA...
WEST-SOUTHWESTERLY MIDDLE TO UPPER LEVEL FLOW IS NOTED ON WATER
VAPOR IMAGERY THIS EVENING OVER THE ENTIRE CARIBBEAN SEA BASIN.
WHILE THIS MIDDLE TO UPPER LEVEL ATMOSPHERE IS RELATIVELY DRY
AND STABLE...AT THE SURFACE...THE MAIN FEATURE IMPACTING THE
BASIN THIS EVENING IS A SHEAR LINE ANALYZED ACROSS HISPANIOLA
NEAR 19N72W TO EASTERN JAMAICA NEAR 18N77W TO JUST OFF THE COAST
OF NICARAGUA NEAR 14N83W. WIDELY SCATTERED LOW-TOPPED SHOWERS
ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE SHEAR LINE. IN
ADDITION...A RECENT ASCAT PASS AROUND 15/1528 UTC INDICATED
STRONGER N-NE WINDS IN THE RANGE OF 20 TO 30 KT NORTHWEST OF THE
BOUNDARY. THE SHEAR LINE IS EXPECTED TO BECOME DIFFUSE OVER THE
NEXT 12 TO 24 HOURS AS A BROAD SURFACE RIDGE CURRENTLY OVER THE
EASTERN GULF OF MEXICO BUILDS EASTWARD INTO THE SW NORTH ATLC.
AS THE PRESSURE GRADIENT TIGHTENS BETWEEN 65W AND 80W BY LATE
SATURDAY...AN AREA OF 20 TO 25 KT TRADE WINDS IS EXPECTED ACROSS
PORTIONS OF THE CENTRAL CARIBBEAN AND WILL PERSIST THROUGH
TUESDAY. OTHERWISE THIS EVENING...SKIES AND CONDITIONS REMAINS
MOSTLY FAIR ACROSS THE SOUTH-CENTRAL AND EASTERN CARIBBEAN.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS FOUND ON WATER VAPOR
IMAGERY NORTH OF THE DISCUSSION NEAR 44N61W WITH AXIS EXTENDING
SOUTH-SOUTHWEST TO 32N67W TO A BASE NEAR 26N74W. THIS TROUGHING
SUPPORTS A PAIR OF COLD FRONT ANALYZED ACROSS THE CENTRAL ATLC
INTO SOUTHERN PORTIONS OF THE SW NORTH ATLC. THE PRIMARY COLD
FRONT EXTENDS FROM 32N53W TO 25N60W TO NORTHERN HISPANIOLA NEAR
20N71W. WIDELY SCATTERED SHOWERS ARE OCCURRING WITHIN 90 NM
EITHER SIDE OF THE FRONT. A SECONDARY COLD FRONT FOLLOWS
ANALYZED FROM 32N58W TO THE SE BAHAMAS NEAR 22N74W TO 21N76W.
ISOLATED SHOWERS ARE POSSIBLE WITHIN 60 NM EITHER SIDE OF THE
BOUNDARY. THESE TWO FRONTS ARE EXPECTED TO MERGE OVER THE NEXT
24 HOURS WHILE MOVING NE ACROSS THE CENTRAL ATLC. FARTHER
EAST...AN MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 36N26W AND
CONTINUES TO SUPPORTS A 993 MB LOW CENTERED SOUTH OF THE AZORES
NEAR 36N28W. THE ASSOCIATED COLD FRONT ENTERS THE DISCUSSION
AREA NEAR 32N22W AND EXTENDS S-SW ALONG 30N22W TO 25N24W TO
18N31W. A SECONDARY WAVE OF ENERGY IS ALSO NOTED AS A SURFACE
TROUGH AXIS FROM 30N24W TO 23N32W. BOTH OF THESE BOUNDARIES HAVE
VERY LITTLE PRECIPITATION ASSOCIATED WITH THEM AT THIS TIME.

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

$$
HUFFMAN

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