[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 272348
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE MAR 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF
SIERRA LEONE AT 8N13W...AND CONTINUES SW TO 4N18W. THE ITCZ
CONTINUES FROM 4N18W TO 3N27W AND CROSSING THE EQUATOR NEAR 36W
TO THE COAST OF BRAZIL AT 2S46W. SCATTERED MODERATE/ISOLATED
STRONG CONVECTION IS WITHIN 120 NM S OF THE MONSOON E OF 16W TO
INLAND AFRICA. SCATTERED MODERATE CONVECTION IS NEAR THE COAST
OF BRAZIL FROM EQ-1N BETWEEN 47W-44W WITH MUCH STRONGER
CONVECTION JUST INLAND THAT COAST.

...DISCUSSION...

GULF OF MEXICO...
ALOFT...WHAT APPEARS TO BE IDENTIFIED AS A LONGWAVE RIDGE
FEATURE COVERS MOST OF THE GULF N OF 21N. AT THE SURFACE...
A 1021 MB HIGH CENTER IS ANALYZED AT 21 UTC OVER THE FAR NE
GULF AT 29N85W WITH A WEAK RIDGE SE 24N95W. THESE FEATURES
ARE MAINTAINING MOSTLY FAIR CONDITIONS ACROSS THE GULF. AN UPPER
LEVEL DISTURBANCE TO THE W OF THE RIDGE OVER WRN TEXAS IS
TRACKING NE. UPPER LEVEL ERN PACIFIC MOISTURE IS ADVECTING NE
...AND MERGING WITH MOISTURE ASSOCIATED OVER MEXICO AND
W TEXAS WITH THE DISTURBANCE. THIS TOTAL MOISTURE HAS ENCROACHED
INTO THE FAR WRN SECTION OF THE GULF AS SCATTERED TO BROKEN HIGH
CIRRUS CLOUDS. ISOLATED WEAK SHOWERS ARE POSSIBLE TONIGHT
OVER THE FAR WRN WATERS.

A WEAK SURFACE TROUGH IS ANALYZED IN THE SW GULF ALONG 92W S OF
21N WITH NO RELATED SIGNIFICANT WEATHER. BESIDES THE UPPER
LEVEL MOISTURE GRADUALLY SPREADING EWD ACROSS THE NRN PORTION
THROUGH THE NEXT COUPLE OF DAYS...LITTLE OVERALL CHANGE CAN
BE EXPECTED OTHERWISE.

CARIBBEAN SEA...
ALOFT...MAINLY SW FLOW FOUND TO THE SW OF THE WESTERN ATLC DEEP
LAYER TROUGH COVERS MUCH OF THE WESTERN SECTION OF THE SEA.
SATELLITE WATER VAPOR IMAGERY SHOWS MOSTLY MODERATE SUBSIDENCE
PERSISTING OVER THE WESTERN SECTION. THESE ATMOSPHERIC
CONDITIONS CONTINUE TO MAINTAIN TRANQUIL/FAIR CONDITIONS OVER
THE MAJORITY OF THAT PORTION OF THE SEA. A FEW SMALL CLUSTERS
OF SHOWERS AND WEAK ISOLATED TSTMS ARE N OF 15N W OF 75W. THE
CLOUD TOPS OF AFTERNOON CONVECTION THAT FIRED UP OVER THE MOST
OF THE LARGER CARIBBEAN ISLANDS ARE NOW WARMING...THUS
CONVECTION IS DISSIPATING.

A WEAKER SURFACE PRES GRADIENT IS ALLOWING FOR LIGHTER TRADE WIND
FLOW (NE-E 10-15 KT WINDS) THEN WHAT HAD BEEN SEEN OVER THE PAST
SEVERAL DAYS. THE EXCEPTION REMAINS THE FAR SW CARIBBEAN BETWEEN
THE COAST OF COLOMBIA AND PANAMA WHERE THE GENERALLY CLIMO
TIGHTER PRES GRADIENT THERE IS BRINGING NE WINDS OF 20-25 KT
TO THOSE WATERS. A RESULT OF THESE STRONGER NE WINDS IS LOW-LEVEL
SPEED CONVERGENCE ALONG THE COASTS OF COSTA RICA AND PANAMA WHERE
PATCHES OF BROKEN TO OVERCAST LOW/MID LEVEL CLOUDS WITH SCATTERED
SHOWERS AND AT TIMES WEAK ISOLATED TSTMS ARE OCCURRING. THE NE
20-25 KT WINDS ARE EXPECTED TO SLACKEN SOME AT THE END OF THE
WEEK. ISOLATED SHOWERS IN THE TRADE WIND FLOW ARE SEEN ACROSS
THE CENTRAL AND ERN CARIBBEAN E OF 69W...AND ALSO S OF 17N
BETWEEN 69W AND 74W.

LAST VISIBLE SATELLITE IMAGERY ALONG WITH GOES-R DUST
ENHANCEMENTS SHOWED THAT THE WRN FRINGE OF AN AREA OF AFRICAN
DUST HAS MOVED INTO THE  ERN CARIBBEAN. LITTLE CHANGE IS EXPECTED
IN THESE CONDITIONS OVER THE NEXT 48 HOURS.

ATLANTIC OCEAN...
OVER THE WESTERN PORTION OF THE AREA...A DEEP LAYER TROUGH
IS PRESENT BETWEEN 57W AND 76W WITH ITS AXIS ROUGHLY EXTENDING
FROM NEAR 32N64W SW TO 26N65W TO 21N73W. THE TROUGH IS ASSOCIATED
WITH A LARGE AND DEEP SURFACE LOW WELL N OF THE DISCUSSION AREA.
IT CURRENTLY SUPPORTS A COLD FRONT THAT ENTERS THE AREA THROUGH
32N59W...AND EXTENDS SW TO 26N65W TO 25N70W WHERE IT BEGINS TO
DISSIPATE WNW TO JUST E OF THE SE FLORIDA. ISOLATED SHOWERS ARE
POSSIBLE WITHIN 60 NM OF THE FRONT. A TROUGH IS WITHIN 120 NM TO
THE SE OF THE FRONT N OF 24N. DEEP ATMOSPHERIC MOISTURE
ADVECTING EASTWARD THROUGH THE SE PERIPHERY OF THE DEEP LAYER IS
TRIGGERING OFF SCATTERED SHOWERS AND TSTMS ALONG A 90 NM WIDE
LINE OUT AHEAD OF THE SURFACE TROUGH THAT EXTENDS FROM 32N53W TO
28N55W TO 25N58W. LIGHTNING DATA INDICATES NUMEROUS STRIKES WITH
THIS ACTIVITY. THE DEEP LAYER TROUGH WILL SHIFT E...THEN PIVOT
NEWD TO N OF THE AREA BY LATE WED NIGHT. THIS WILL DRIVE THE
SURFACE COLD FRONT TO A PSN FROM NEAR 32N48W TO 20N54W TO 17N59W
IN 24 HRS...AND FROM NEAR 32N36W TO 18N50W BY THU AFTERNOON WITH
SW WINDS OF 20-25 KT AHEAD OF N OF 25N AND NW-N WINDS OF 20-30
KT BEHIND IT N OF 27N...BUT WEAKENING TO LESS THAN 20 KT IN 48
HRS. LAST VISIBLE IMAGES AND BUOY OBSERVATIONS SUGGEST THAT A
SURFACE TROUGH MAY BE DEVELOPING TO THE SE OF THE COLD FRONT AND
TROUGH FROM 19N TO 22N BETWEEN 59W AND 61W.

ELSEWHERE OVER THE WESTERN ATLC AND IN OVER THE CENTRAL PART
OF THE ATLC UPPER LEVEL RIDGING DOMINATES. THE RIDGE IN THE WAKE
OF THE DEEP LAYER TROUGH HAS ITS AXIS OVER THE CENTRAL GULF OF
MEXICO...BUT THE EASTERN PERIPHERY OF THE RIDGE IS DEPICTED BY
NW UPPER FLOW INTO THE TROUGH WHERE IT MERGES WITH SW TO W FLOW
FROM THE WESTERN CARIBBEAN  SEA. THIS FLOW COMBINATION IS
OBSERVED AS RATHER CONFLUENT INTO THE TROUGH. AS RESULT...THE
ATMOSPHERE OVER THE MAJORITY OF THE WESTERN ATLANTIC IS VERY
STABLE AS INDICATED BY THE MOSTLY STRONG SUBSIDENCE ALOFT THERE.
SURFACE HIGH PRES RIDGING IS ANALYZED OVER THAT PORTION OF THE
ATLC AS WELL. THESE CONDITIONS ARE HELPING TO GRADUALLY ERODE
THE SURFACE COLD FRONT WITH TIME. THIS PROCESS WILL BE FURTHER
ACCELERATED INTO WED AS A HIGH CENTER OF 1024 MB DROPS SWD INTO
THE FAR NRN PORTION NEAR 30N74W.

IN THE FAR EASTERN ATLC...A HIGHLY AMPLIFIED RIDGE E OF THE DEEP
LAYER TROUGH EXTENDS ALONG 41W N OF 22N. IT MAINTAINS A SURFACE
RIDGE...FROM A 1022 MB HIGH JUST N OF THE AREA AT 33N37W...THAT
STRETCHES SW FROM THE HIGH TO 20N54W. THE HIGH IS FORECAST TO
SHIFT EWD THROUGH THE NEXT 24 HRS. TO THE E OF THE RIDGE...AN
UPPER LEVEL TROUGH EXTENDS FROM 32N23W TO 24N26W TO NEAR 13N27W.
THE TROUGH SUPPORTS A WEAKENING COLD FRONT THAT EXTENDS INTO THE
DISCUSSION AREA NEAR 32N24W AND CONTINUES SW TO NEAR 26N34W.
SATELLITE IMAGERY SHOWS FRACTURED PATCHES OF BROKEN LOW AND MID
LEVEL CLOUDS WITH POSSIBLE ISOLATED SHOWERS N OF 25N BETWEEN
24N-34W.

OVER THE TROPICAL ATLC BROAD UPPER LEVEL RIDGING IS PRESENT
S OF 23N BETWEEN 39W AND 65W. STRONG WLY WINDS ALOFT ARE
ALONG THE NORTHERN CREST OF THIS RIDGE AS A JET STREAM BRANCH
RIDES UP FROM WESTERN CARIBBEAN NE TO OVER THE CREST OF THE
RIDGE AND DIVES SEWD TO ROUND THE BASE OF THE E ATLC UPPER
LEVEL TROUGH. UPPER LEVEL MOISTURE IN THE FORM OF SCATTERED
TO BROKEN HIGH CIRRUS CLOUDS ARE BEING CHANNELED NE AND E
UP OVER THE RIDGE IN THE STRONG WLY FLOW.

LAST VISIBLE SATELLITE IMAGERY ALONG WITH GOES-R DUST
ENHANCEMENTS REVEALED THAT AN AREA OF AFRICAN DUST EXTENDED
ACROSS THE TROPICAL ATLC TO THE ERN CARIBBEAN MOSTLY S OF 20N
REACHING...BUT EXTENDING FARTHER N ALONG THE AFRICAN COAST.

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

$$
AGUIRRE






This weather bulletin was brought to you by:
www.nashvilleweather.net