000
AXNT20 KNHC 152339
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SAT MAR 15 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 
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
2115 UTC.

...THE ITCZ...

ITCZ AXIS IS CENTERED ALONG 6N10W 3N20W 1N29W CROSSING THE 
EQUATOR NEAR 33W TO 3S44W. SCATTERED MODERATE CONVECTION IS FROM 
THE EQUATOR TO 2N BETWEEN 32W-36W. ISOLATED MODERATE CONVECTION 
IS WITHIN 240 NM N OF THE AXIS BETWEEN 17W-27W.

...DISCUSSION...

GULF OF MEXICO...
A STRENGTHENING LOW PRES SYSTEM OVER THE APPALACHIANS IS 
DRAGGING A COLD FRONT ACROSS THE MISSISSIPPI VALLEY TO THE NW 
GULF...ANALYZED FROM S CENTRAL LOUISIANA TO JUST S OF 
BROWNSVILLE TEXAS AT 21Z. ALL OF THE ASSOCIATED ACTIVE/SEVERE 
WEATHER IS WELL N OF THE REGION LEAVING ONLY A FEW CLOUDS NEAR 
THE FRONT. THIS FRONT IS VERY WEAK IN THE GULF...IN FACT TEMPS 
ARE SUMMER-LIKE OVER S TEXAS WITH LAREDO REPORTING 101 F THIS 
AFTERNOON...OBVIOUSLY SHOWING NO COOL AIR ASSOCIATED WITH THE 
BOUNDARY IN THAT REGION. AHEAD OF THE FRONT...THE VERY 
INTERESTING AND UNUSUAL CLOUD FEATURE KNOWN AS AN UNDULAR BORE 
SEEN EARLIER HAS JUST ABOUT DIMINISHED...STILL A WEAK TROUGH WAS 
ANALYZED ALONG ITS QUICKLY WEAKENING SIGNATURE. ELSEWHERE 
...MAINLY FAIR WARM AND HUMID WEATHER EXISTS BENEATH ZONAL FLOW 
AND STRONG SUBSIDENCE ALOFT AND BRISK S TO SW WINDS AT THE 
SFC...ESPECIALLY OVER THE MIDDLE AND EASTERN WATERS  

CARIBBEAN SEA...
A SPRAWLING SUBSIDENT MID-UPPER RIDGE IS CENTERED MIDWAY BETWEEN 
HISPANIOLA AND N VENEZUELA SUPPRESSING THE FORMATION OF DEEP 
CLOUDINESS. EVEN THE TYPICAL SHALLOW CLOUD PATCHES APPEAR 
SUPPRESSED THIS EVENING WITH ONLY ONE AREA HAVING SOME 
SIGNIFICANCE W OF JAMAICA FROM 15N-19N BETWEEN 80W-83W...WHERE 
THE LOW-LEVEL FLOW IS CONFLUENCE BETWEEN THE ELY WINDS OVER THE 
EASTERN CARIB AND BRISK SLY WINDS IN THE SE GULF. THE LACK OF 
SHALLOW MOISTURE OVER THE REMAINDER OF THE REGION IS LIKELY DUE 
TO THE RELAXED TRADE WINDS BROUGHT ABOUT BY THE WEAK PRES 
PATTERN N OF THE REGION.  

ATLANTIC OCEAN...
A MID-UPPER SHORTWAVE OFF THE EASTERN CONUS IS PRODUCING PATCHES 
OF DEEP CLOUDS AND EMBEDDED SCATTERED SHOWERS AND TSTMS FROM 
28N-31N BETWEEN 64W-69W AND N OF 29N BETWEEN 73W-76W. LIGHTNING 
DATA SHOWS A STEADY DECLINE IN STRIKES IN BOTH OF THESE AREAS 
OVER THE LAST FEW HOURS. THIS SHORTWAVE MAY PLAY A ROLE IN 
HELPING THE LOW PRES SYSTEM OVER THE EASTERN U.S. RAPIDLY DEEPEN 
IN THE W ATLC TONIGHT THROUGH MON. 

MODEST MID-UPPER RIDGING LIES E OF THE SHORTWAVE BETWEEN 50W-65W 
ADVECTING ABUNDANT MID-HIGH LEVEL CLOUDS N OF 29N IN THAT 
LONGITUDE RANGE. LARGE-SCALE MID-UPPER TROUGHING IS THE THEME E 
OF THAT RIDGE WITH THE AXIS EXTENDING INTO THE REGION ALONG 38W 
OR SO WELL S INTO THE DEEP TROPICS. AN ASSOCIATED SLOW MOVING 
FRONT ENTERS THE REGION NEAR 32N34W AND CONTINUES SW TO A 1016 
MB LOW NEAR 25N42W THEN WSW AS A NON-THERMAL TROUGH TO 25N55W. 
SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 180 NM E OF THE 
FRONT N OF 25N. A COUPLE OF WEAK LOW-LEVEL FEATURES ARE 
MEANDERING IN THE CENTRAL ATLC...BUT THESE ARE BENIGN AND NOT 
WORTH MENTIONING. A MID-UPPER RIDGE IS CENTERED OVER THE 
TROPICAL E ATLC NEAR 3N21W. DIFFLUENCE ALOFT ON THE SW PERIPHERY 
OF THE RIDGE IS ENHANCING CONVECTION IN THE ITCZ W OF 
32W...ESPECIALLY S OF THE EQUATOR.

$$
CANGIALOSI