[Tropical] Tropical Weather Discussion

[EMWIN Server]

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




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