[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180515
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SUN MAR 18 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...ITCZ...

ITCZ AXIS IS ALONG 9N12W 5N20W 3N26W TO NEAR EQ48W. CONVECTION
HAS DECREASED CONSIDERABLY DURING THE PAST 24 HRS. ONLY ISOLATED
MODERATE CONVECTION NOTED WITHIN 90 NM EITHER SIDE OF THE AXIS.

...DISCUSSION...

GULF OF MEXICO...
A WELL DEFINED UPPER LEVEL TROUGH WITH IT'S AXIS ALONG 75W HAS
BEGUN TO SHIFT EWD. UPPER WINDS OVER THE GULF AREA ARE NWLY AT
40 TO 60 KT. A 1025 MB HIGH LOCATED ALONG THE COAST OF LOUISIANA
IS MOVING SLOWLY EWD. NLY WINDS TO 20 KT CONTINUE E OF 90W
TONIGHT WHILE N OF 25N W OF 90W WINDS HAVE SHIFTED TO E AND SE
10 TO 15 KT. S OF 25N W OF 90W WINDS ARE MOSTLY N TO NE 10 TO 15
KT. LATEST WATER VAPOR IMAGERY SHOWS VERY DRY AIR OVER THE SRN
HALF OF THE GULF RESULTING IN CLEAR SKIES. THE CENTER OF THE
SURFACE HIGH IS EXPECTED TO SHIFT EASTWARD OVER THE NEXT COUPLE
OF DAYS...BUT HIGH PRESSURE RIDGE WILL REMAIN IN CONTROL OF THE
GULF THROUGH TUE.

CARIBBEAN...
A COLD FRONT LIES OVER SE CUBA AND CONTINUES TO MOVE ESE. A
MODERATE NLY FLOW IS EVIDENT BEHIND THE FRONT OVER THE NW
CARIBBEAN WITH SCATTERED TO BROKEN CLOUDS AND ISOLATED SHOWERS.
CONSIDERABLE CLOUDINESS IS NOTED OVER HAITI AND WRN PORTIONS OF
THE DOMINICAN REPUBLIC. EARLIER CONVECTION HAS DIMINISHED AND
MOVED NE OVER ATLC WATERS. ELY TRADES DOMINATE THE ERN CARIBBEAN
WITH SCATTERED CLOUDS AND ISOLATED WEAK SHOWERS. IN THE UPPER
ATMOSPHERE A BROAD ANTICYCLONE COVERS THE ERN HALF OF THE
CARIBBEAN WHILE OVER THE WRN HALF THE FLOW ALOFT IS MOSTLY SWLY.
HIGH LEVEL CLOUDINESS FROM EARLIER CONVECTION OVER COLOMBIA AND
WRN VENEZUELA WAS BEING ADVECTED N AND NE OVER THE ERN PORTION.

SW ATLANTIC...

STRONG UPPER TROUGH WITH AXIS ALONG 75W ROTATING RAPIDLY EWD.
BROAD SWATH OF VERY DRY UPPER LEVELS OVER BAHAMAS SHIFTING E.
STRONG DIFFLUENT PATTERN ALOFT E OF TROUGH AXIS AIDING ISOLATED
CONVECTION S OF 25N BETWEEN 60W AND 70W.  A COLD FRONT LIES OVER
THE SE BAHAMAS TONIGHT AND SE CUBA. THE FRONT IS MOVING SE 15
KT. MULTILAYERED CLOUDINESS 200 NM WIDE IS ASSOCIATED WITH THE
FRONT WITH EMBEDDED SHOWERS AND TSTMS. MOST OF THE ENERGY WITH
THIS FEATURE IS SHIFTING N OF 30N AHEAD OF THE FRONT AND MOST
FRONTAL CONVECTION HAS BEEN ON THE DECLINE THE PAST FEW HRS.
OVER THE ATLC S OF 20N W OF 40W LATEST SATELLITE PICTURES SHOW
SCATTERED TO BROKEN LOW AND MID CLOUDS MOVING W 20 KT WITH
ISOLATED LIGHT SHOWERS.

ERN ATLANTIC...

A CLOSED UPPER LOW THAT WAS JUST N OF THE CANARY ISLANDS HAS
FLATTENED OUT AND BECOME STATIONARY. SCATTERED CONVECTION NEAR
THE CENTER HAS DECREASED INDICATING THE SYSTEM HAS WEAKENED THE
PAST 24 HR. WATER VAPOR IMAGERY SHOWS A NARROW BAND OF CIRRUS
ASSOCIATED WITH A JET STREAM ALONG 16N40W EWD OVER THE CAPE
VERDE ISLANDS. QUIKSCAT DATA SHOWS WIND VELOCITIES 60 TO 80 KT
WITH THIS JET. ON THE SURFACE STRONG HIGH PRESSURE CENTERED WELL
N OF THE REGION ALONG 30W EXTENDS S TO 10N E OF 50W. THE RIDGE
IS RESPONSIBLE FOR A MODERATE TO FRESH NE FLOW OF COOL AIR. THE
AIR PICKS UP MOISTURE FROM THE ATLC AND PRODUCES SCATTERED TO
BROKEN LOW AND MID CLOUDINESS THROUGHOUT THIS REGION.

$$
RRG





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