[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 032340
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE APR 3 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N10W 2N2OW EQ35W  1S50W. WIDELY
SCATTERED MODERATE CONVECTION IS FROM 1N-7N BETWEEN 15W-23W AND
JUST SOUTH OF THE EQUATOR BETWEEN 26W-38W. AN AREA OF MODERATE
CONVECTION CAME OFF THE AFRICAN COAST YESTERDAY EVENING. IT HAS
BEEN MOVING WESTWARD AND A SFC TROUGH IS ANALYZED ON THE 18Z MAP
FROM 9N15W TO EQ18W.

...DISCUSSION...

GULF OF MEXICO...
A MID/UPPER LEVEL RIDGE DOMINATES THE GULF...WITH THE AXIS
EXTENDING NORTH FROM WRN CUBA THROUGH THE SE US TOWARD THE GREAT
LAKES. A SHORT WAVE TROUGH IS OVER NW MEXICO MOVING SLOWLY EWD.
SWLY UPPER FLOW BETWEEN THE TROUGH AND THE RIDGE IS TRANSPORTING
ABUNDANT UPPER LEVEL MOISTURE FROM THE EPAC ACROSS NORTH-CENTRAL
MEXICO INTO THE GULF AND THE SE US. THESE WINDS ARE ALSO
ENHANCING THE CONVECTIVE ACTIVITY OVER MEXICO AND THE NW CORNER
OF THE GULF. THE MOSAIC DOPPLER RADAR FROM THE SE US SHOWS
SCATTERED SHOWERS AND ISOLATED TSTMS MAINLY OVER PARTS OF
SOUTH-CENTRAL LOUISIANA AND NORTHERN GEORGIA WHERE A SPOTTER
REPORTED HEAVY RAIN AND HAIL. AT THE SFC...A WEAK HIGH PRES
RIDGE EXTENDS ACROSS THE GULF. THIS RIDGE IS PRODUCING LIGHT TO
MODERATE SE TO S RETURN FLOW. AS OF 21Z...A 1020 MB HIGH IS OVER
THE NE CORNER OF THE GULF. ACCORDING TO THE GFS MODEL...A WEAK
COLD FRONT IS FORECAST TO ENTER THE N GULF WATERS ON WEDNESDAY
VEERING THE WINDS TO THE NE BEHIND IT.

CARIBBEAN SEA...
A 1020 MB SFC HIGH SITUATED NORTH OF THE AREA IS STILL PRODUCING
MODERATE TO STRONG TRADE WINDS OF 20 TO 30 KT ACROSS THE
BASIN...ESPECIALLY SOUTH OF 15N WEST OF 68W. TYPICAL FRAGMENTS
OF LOW/MID CLOUDS ARE MOVING WESTWARD ACROSS THE REGION. A
NARROW BAND OF HIGH CLOUDS IS JUST SOUTH OF THE GREATER ANTILLES
ON THE NORTHERN PERIPHERY OF A BROAD UPPER RIDGE THAT DOMINATES
CENTRAL AMERICA AND THE CARIBBEAN SEA. THIS FEATURE IS ALIGNED
E-W ACROSS NRN SOUTH AMERICA AND THEN EXTENDS NW FROM COLOMBIA
TO WRN CUBA SUPPRESSING THE DEVELOPMENT OF DEEP MOISTURE.
HOWEVER...CLUSTERS OF MODERATE CONVECTION HAVE DEVELOPED OVER
PARTS OF COLOMBIA AND PANAMA DUE TO THE PRESENCE OF THE EPAC
ITCZ AND A DIFFLUENT PATTERN ALOFT ASSOCIATED WITH THE WESTERN
PERIPHERY OF THE ABOVE MENTIONED UPPER RIDGE. THE WEAK SFC RIDGE
N OF THE AREA WILL CONTINUE TO SLOWLY WEAKEN ALLOWING THE TRADES
TO SLACKEN WED THROUGH SAT.

ATLANTIC OCEAN...
A RIDGE/TROUGH/RIDGE PATTERN CONTINUES TO DOMINATE THE FORECAST
AREA. DRY AIR ALOFT RESULTING IN MODERATE TO STRONG SUBSIDENCE
IS KEEPING MOST OF THE AREA RATHER TRANQUIL WITH ONLY SHALLOW
PATCHES OF LOW-LEVEL MOISTURE. A WEAK SFC RIDGE COVERS THE W
ATLC AND THE STATE OF FLORIDA WITH A 1020 MB HIGH LOCATED NEAR
28N75W. THE WEAK PRES PATTERN IS KEEPING WINDS GENERALLY LIGHT
TO MODERATE ACROSS THE REGION. A COUPLE OF SFC TROUGHS ARE
MOVING INTO THE AREA. ONE IS THE SOUTHERN EXTENSION OF A COLD
FRONT AND EXTENDS ALONG 31N35W 28N43W 30N50W WITH SCATTERED
SHOWERS. THE SECOND ONE IS ASSOCIATED WITH A DEEPENING SFC LOW
MOVING SE ACROSS THE CENTRAL ATLC BETWEEN 30N AND 35N. THIS
FEATURE WITH GALE FORCE WINDS IS FORECAST TO REMAIN N OF THE
AREA BUT WILL BRING AN INCREASE IN WINDS AND SEAS OVER THE
FORECAST AREA N OF 25N BETWEEN 40W-60W DURING THE NEXT 12-24
HOURS. THE SFC TROUGH IS WELL DEFINED ON SAT IMAGERY WHERE A
BAND OF LOW/MID CLOUDS WITH EMBEDDED SHOWERS IS SEEN ALONG 30N
BETWEEN 57W-65W. A COLD FRONT ENTERS THE REGION NEAR 31N26W THEN
CONTINUES MAINLY S TO 22N35W. THIS FRONT HAS LIMITED MOISTURE
WITH ONLY A LINE OF LOW CLOUDS AND ISOLATED SHOWERS WITHIN 60 NM
AHEAD OF IT. ANOTHER SFC TROUGH...REMNANTS OF THIS FRONTAL
BOUNDARY GOES FROM 22N35W TO 13N52W. WEAK HIGH PRES RIDGING LIES
JUST E OF THE FRONT ANCHORED BY A 1020 MB HIGH BETWEEN THE
CANARY AND MADEIRA ISLANDS NEAR 31N15W.

$$
GR





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