[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 301802
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON APR 30 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 4N20W 2N30W 2N40W CROSSING THE
EQUATOR NEAR 45W. NUMEROUS MODERATE TO STRONG CONVECTION IS
WITHIN 150NM N AND 210NM S OF THE AXIS E OF 21W TO THE AFRICAN
COAST. ISOLATED MODERATE CONVECTION IS WITHIN 180 NM N OF THE
AXIS BETWEEN 25W-46W.

...DISCUSSION...

GULF OF MEXICO...
WEAK SFC RIDGING CONTINUES TO CONTROL THE GULF THIS AFTERNOON
AROUND A 1021MB HIGH PRES CENTER NEAR 28N89W. THIS IS PRODUCING
ABUNDANT CLEAR SKIES...WINDS MOSTLY BELOW 15KT...AND SEAS MOSTLY
BELOW 4' ACROSS THE GULF. MOISTURE CONTENT/CLOUD COVER CONTINUES
TO BE GREATEST IN THE FAR WRN GULF WITH LOW LEVEL SE FLOW. IN
ADDITION...UPPER MOISTURE IS PUSHING E INTO THE WRN GULF AHEAD
OF THE CONVECTION OVER TX ASSOCIATED WITH THE PRONOUNCED UPPER
LOW NEAR THE TX/NM BORDER. VERY DRY AIR IS SEEN IN WV IMAGERY
OVER THE ERN GULF...BEING ADVECTING SE WITH NW FLOW ON THE E
SIDE OF A MID LEVEL RIDGE. SFC HIGH PRES OVER THE N GULF WILL
SLIDE E OVER THE NEXT COUPLE OF DAYS...ALLOWING RETURN FLOW TO
BE STRONGEST/MOISTURE TO BE HIGHEST IN THE WRN PORTION.

CARIBBEAN SEA...
MODERATE TO FRESH TRADE FLOW WITH TYPICAL LOW LEVEL MOISTURE
PATCHES DOMINATE MUCH OF THE BASIN E OF 80W. HOWEVER...THE LOW
LEVEL CLOUD MOTIONS IN THE NE PORTION...MAINLY N OF 16N AND E OF
72W...ARE MORE FROM THE SE AHEAD OF THE REMNANT FRONTAL TROUGH
EXTENDING NE FROM THE BAHAMAS. THIS HAS SUPPLIED GOOD LOW LEVEL
MOISTURE TO THE LEEWARD ISLANDS THROUGH HISPANIOLA...WHICH HAS
COMBINED WITH DIURNAL HEATING TO SUPPORT THE SHOWER ACTIVITY
NOTED FROM THE SAN JUAN RADAR. THE MAIN FEATURE W OF 80W IS THE
SFC TROUGH NEAR THE COAST OF NICARAGUA/HONDURAS ALONG 18N81W
12N83W. THIS IS GENERATING SCATTERED SHOWERS/ISOLATED TSTMS FROM
15N-19N BETWEEN 80W-86W. UPPER FLOW REMAINS HIGHLY ZONAL WITH
JUST GENTLE RIDGING IN PLACE. SIMILAR TRADE WIND REGIME EXPECTED
THE NEXT COUPLE OF DAYS WITH ATLC HIGH PRES REMAINING N OF THE
AREA.

ATLANTIC...
WEAK SFC HIGH PRES IS BUILDING INTO THE THE WRN ATLC BEHIND THE
REMNANT FRONTAL TROUGH THAT ENTERS THE AREA NEAR 31N61W AND
CONTINUES SW TO THE SE BAHAMAS NEAR 23N75W. SATELLITE IMAGERY
SHOWS A SECOND LOW LEVEL CONFLUENT ZONE ABOUT 90NM BEHIND THE
ANALYZED TROUGH. THE LEADING BOUNDARY SEEMS MORE SIGNIFICANT AND
CONTINUOUS SO HAVE OPTED FOR ONLY ANALYZING THIS FEATURE.
SUSPECT WHAT WE ARE SEEING IS AN OLD PREFRONTAL TROUGH BEGINNING
TO MERGE WITH THE MAIN PORTION OF THE OLD COLD FRONT.
REGARDLESS...SCATTERED SHOWERS/ISOLATED TSTMS ARE WITHIN 60NM
EITHER SIDE OF A LINE EXTENDING NE FROM CROOKED ISLAND TO
30N61W. VISIBLE IMAGERY ALSO CONTINUES TO SHOW THE SMOKE
DISPERSING THROUGH FLORIDA AND THE WRN ATLC ASSOCIATED WITH THE
WILDFIRES IN SE GEORGIA. OTHERWISE THE REMAINDER OF THE ATLC
DISCUSSION AREA IS DOMINATED BY THE SRN PERIPHERY OF A 1030 MB
SFC HIGH S OF THE AZORES NEAR 34N29W. THIS IS PRODUCING
WIDESPREAD FAIR WEATHER AND MODERATE TO FRESH TRADES E OF 50W.
WEAK HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE WRN ATLC
WHILE STRONGER/LARGER HIGH PRESSURE REMAINS IN CONTROL OF THE
ERN ATLC. WEAK CONFLUENCE BETWEEN THESE TWO HIGHS WILL SUPPORT
THE SLOWLY DYING FRONTAL TROUGH NE OF THE SE BAHAMAS OVER THE
NEXT DAY OR SO.


$$
WILLIS




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