[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 061757
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST SUN FEB 06 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND 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
1715 UTC.

...ITCZ...

ITCZ AXIS ANALYZED FROM 06N20W TO 02N34W TO 02N43W THEN INTO THE
MOUTH OF THE AMAZON BASIN ACROSS EQUATORIAL BRAZIL. CONVECTION
NEAR THE AXIS HAS DIMINISHED IN THE PAST 24 HOURS...WITH
SCATTERED MODERATE AND ISOLATED STRONG CONVECTION NOTED WITHIN
210 NM N OF AXIS W OF 38W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD LONGWAVE TROUGH CONTINUES ACROSS THE U.S. TODAY...WITH
SEVERAL SHORTWAVES AND SMALL CYCLONES ROTATING THROUGH THIS
FEATURE. BROAD SRN END OF TROUGH CURVED CYCLONICALLY ACROSS
MEXICO N OF 23N...WITH SWLY FLOW IN EXCESS OF 100 KT ALOFT
ACROSS THE N AND NE GULF. UPPER RIDGE TO THE SE WAS CENTERED
OVER THE CARIBBEAN JUST NW OF JAMAICA. AN OLD FRONTAL BOUNDARY
REMAINS DRAPED ACROSS THE SE GULF...FROM THE W ATLC SW ACROSS
SRN FLORIDA TO JUST SOUTH OF NAPLES THEN CONTINUES RELATIVELY
STATIONARY TO NEAR 24N87W...THEN EXTENDS W-SW THEN W AS AN ILL
DEFINED WARM FRONT LIFTING N IN INCREASING SLY LLVL FLOW. NARROW
BANDS OF SHALLOW CONVECTION WERE DEPICTED BY NWS RADAR NETWORK
EXTENDING NE TO SW ACROSS CENTRAL AND N FLORIDA IN THE COOLER
AIR NW OF THE FRONT...WHILE PATCHES OF STRATIFORM PRECIP WITH
EMBEDDED SHALLOW CONVECTION WAS SPREAD ACROSS THE NE GULF E OF
90W. A SHORTWAVE DIVING S THROUGH THE BACKSIDE OF THE UPPER
TROUGH WAS MOVING ACROSS NEW MEXICO AND INTO WRN TEXAS...WITH A
ACCOMPANYING SURFACE LOW AND DEVELOPING COLD FRONT. THESE
FEATURES ARE FORECAST TO MOVE SE INTO SE AND E TEXAS TONIGHT AND
TRANSPORT A NEW COLD FRONT MOVING OFF THE TEXAS AND LOUISIANA
COASTS MON MORNING. THE CURRENT OLD FRONT ACROSS THE GULF WILL
DRIFT N ACROSS FLORIDA AND THE ERN GULF THROUGH MON MORNING
BEFORE THE BOUNDARIES MERGE ACROSS THE FAR SE GULF AND FLORIDAS
ATLC WATERS MON NIGHT.

CARIBBEAN SEA...
WATER VAPOR IMAGERY INDICATES VERY DRY AIR ALOFT ACROSS MOST OF
THE BASIN DUE TO A TUTT AXIS EXTENDING E TO W ALONG 15N. STRONG
CONVERGENCE ALONG THE N SIDE OF THIS AXIS WAS PRODUCING STRONG
SUBSIDENCE ACROSS THE NE CARIB EXTENDING W TO THE WINDWARD
PASSAGE. AS MENTIONED ABOVE...AN UPPER ANTICYCLONE WAS CENTERED
JUST NW OF JAMAICA WITH RIDGE EXTENDING NE TO NEAR 30N62W. AT
LOW LEVELS...MODERATE TO FRESH ELY TRADES CONTINUE ACROSS THE
CARIB E OF 80W...WITH WINDS 25-30 KT IN THE SW CARIB AND HIGHEST
OFF THE COAST OF COLOMBIA. ABOVE THE BOUNDARY LAYER...LOW LEVEL
FLOW HAS BEGUN TO VEER MORE E-SE ACROSS THE NE CARIB AND GREATER
ANTILLES AND WILL AID IN FOCUSING AFTERNOON CONVECTION SHIFTED
MORE NW THAN IN TYPICAL ELY TRADE WIND FLOW. WEAKER TRADES W OF
80W PREVAILED...WHILE A WELL DEFINED LOW LEVEL CYCLONE APPEARED
CENTERED JUST N OF PANAMAS...AND WAS PART OF THE EPAC MONSOONAL
CIRCULATION...AND LIGHT TO MODERATE E TO SE WINDS PREVAILED
ACROSS NW PORTIONS. CLUSTERS OF STRATOCU WITH BANDS OF SHALLOW
CONVECTION WERE NOTED PASSING S OF JAMAICA AND SPREAD ACROSS THE
WATERS W OF 82W. TYPICAL UPSLOPE YET SHALLOW CONVECTION SHOULD
BE EXPECTED ACROSS THE CARIBBEAN COASTS OF CENTRAL AMERICA
THROUGH THIS EVENING.

HIGH PRESSURE ACROSS THE CENTRAL ATLC WILL SINK SLIGHTLY SE
OVERNIGHT AND TIGHTEN THE PRESSURE GRADIENT ACROSS THE TROPICAL
ATLC AND INTO THE ERN CARIBBEAN...AND FRESHEN THE TRADE WIND
FLOW E OF 70W. THIS WILL INCREASE THE FREQUENCY OF PASSING
SHOWERS ACROSS THE ERN CARIB THIS AFTERNOON THROUGH MON MORNING.

ATLANTIC OCEAN...
UPPER LEVEL TROUGHING ACROSS THE CENTRAL AND NE CONUS IS
SUPPORTING A COLD FRONT THAT WAS ANALYZED OFFSHORE OF THE
EASTERN U.S. SEABOARD AT 1200 UTC FROM 32N75.5W SW TO THE
FLORIDA PENINSULA N OF VERO BEACH. MOSAIC DOPPLER RADAR
IMAGERY INDICATES MID-LEVEL MOISTURE OVERRUNNING THE FRONTAL
BOUNDARY PRODUCING NARROW BANDS OF SHALLOW SCATTERED SHOWERS
WITHIN 180 NM NW OF THE FRONT. THE REMAINDER OF THE N ATLC S OF
30N IS UNDER THE INFLUENCE OF THE ATLANTIC HIGH PRES RIDGE
CENTERED ON A PAIR OF 1028 MB HIGHS...WITH A MEAN CENTERPOINT
NEAR 34N43W. A LOW LEVEL TROUGH HAS MOVED OFF THE W COAST OF
AFRICA IN THE PAST FEW DAYS...CROSSED THE CAPE VERDES...AND WAS
ALONG ABOUT 30W THIS MORNING...AND HELPING TO PRODUCE A MODERATE
PRES GRADIENT ACROSS THE TROPICAL ATLC...YIELDING NELY TRADES OF
20-25 KT S OF 21N FROM 30W TO JUST E OF THE LESSER ANTILLES. THE
LOW TO MID LEVEL REMNANTS OF A TUTT INDUCED TROUGH...AND ITS
ASSOCIATED ENHANCED MOISTURE...WERE MOVING W TO W-NW ACROSS THE
NE CARIB AND ADJACENT ATLC WATERS PRODUCING SCATTERED CLUSTERS
OF TRADEWIND SHOWERS THAT WILL BE ENHANCED AS THEY MOVE ACROSS
THE ISLANDS THIS AFTERNOON AND EVENING.

EAST OF 30W...DRY AND STABLE SAHARAN AIR DOMINATED FROM N OF THE
ITCZ TO THE CANARY ISLANDS...YIELDING NEARLY CLOUD FREE SKIES.
TO THE W OF THIS SAHARAN AIR WAS A WEAK LOW TO MID LEVEL
INVERTED TROUGH THAT EXTENDED FROM NEAR 20N31W SW TO NEAR
12N36W...AND WAS ENTRENCHED IN A ZONE OF ENHANCED LOW LEVEL
MOISTURE THAT WAS PRODUCING A BROAD AREA OF SCATTERED TO
NUMEROUS SHALLOW CONVECTION...WITH ISOLATED MODERATE
CONVECTION.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
STRIPLING





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