[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 280004
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE FEB 27 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
2345 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 5N10W 3N20W...CROSSING THE
EQUATOR AT 31W...INTO NORTHEASTERN BRAZIL NEAR 4S43W. ISOLATED
CLUSTERS OF MODERATE CONVECTION ARE WITHIN 120 NM EITHER SIDE OF
THE AXIS BETWEEN 12W-23W. SCATTERED MODERATE IS FROM 4S-3N
BETWEEN 34W-47W.

...DISCUSSION...

THE GULF OF MEXICO...
VERY COMPLEX FRONTAL PATTERN DOMINATES THE N AND E GULF THIS
EVENING. THE SYNOPTIC SIGNAL HAS BECOME QUITE BLURRY WITH
NUMEROUS BOUNDARIES EVIDENT FROM SEA BREEZES...OLD FRONTS...AND
THE CONVECTION IN THE SE GULF AND S FLORIDA. THE VERY WEAK SFC
PRES GRADIENT OVER THE E GULF IS NOT HELPING TO SORT THINGS OUT.
HOWEVER...IN THE MIDST OF THE CONFUSION AS OF 27/2100 UTC MY
BEST HYPOTHESIS TO WHAT IS GOING ON ENTAILS THIS...A 1011 MB SFC
LOW HAS FORMED OVER NE FLORIDA THAT HAS A STATIONARY FRONT
RIDING THE GULF COAST THEN CUTTING INLAND THROUGH MISSISSIPPI
AND LOUISIANA. THIS BOUNDARY IS SEPARATING A STRONG DEWPOINT
GRADIENT WELL BUT NOT AS MUCH WITH TEMPS...WITH PLENTY OF CLEAR
SKIES AND SUNSHINE HEATING UP THE SE U.S. SFC OBS AND THE LAST
FEW VISIBLE PICTURES THIS EVENING CLEARLY SHOW A TROUGH
EXTENDING FROM JUST NORTH OF LAKE OKEECHOBEE TO A PSN IN THE SE
GULF NEAR 25N88W. SCATTERED SHOWERS WITH EMBEDDED TSTMS ARE
WITHIN 90 NM OF THIS TROUGH...MAINLY TO THE S AND E OF THE
AXIS...AND ARE AFFECTING SRN FLORIDA AND ADJACENT WATERS.
ELSEWHERE AT THE SFC...A 1014 MB HIGH IS JUST OFFSHORE SE
LOUISIANA. ALOFT...ZONAL FLOW IS DOMINATING WITH VERY DRY AIR
SEEN IN WV IMAGERY N OF 27N AND JUST OFFSHORE MEXICO. THE STRONG
WLY FLOW IS PUSHING THE MOISTURE OVER THE AFOREMENTIONED
CONVECTION QUICKLY TO THE E INTO THE SW N ATLC. SFC HI PRES N OF
THE AREA WILL PUSH E WED IN ADVANCE OF THE NEXT FRONT TO PUSH
OFF THE TX COAST DURING THU. RETURN FLOW WILL GRADUALLY INCREASE
IN ADVANCE OF THE FRONT...SEE OFFSHORE WATERS FORECAST UNDER
HEADER MIAOFFNT4 FOR DETAILS.

THE CARIBBEAN SEA...
ABUNDANT WLY UPPER LEVEL FLOW AND DRY AIR/SUBSIDENCE CONTINUE TO
AFFECT THE CARIBBEAN BASIN. EXCEPTION IS SLIGHTLY INCREASING
UPPER MOISTURE IN THE FAR NW PORTION DOWNSTREAM FROM CONVECTION
IN THE SE GULF. MODERATE TO STRONG TRADES CONTINUE E OF
80W...WITH A GALE WARNING NOW IN EFFECT FOR ELY FLOW NEAR THE
COLOMBIAN COAST. WINDS ARE A BIT LIGHTER W OF 80W...AND BEND NE
S OF 16N AROUND THE COLOMBIAN LOW...AND MORE SE TO THE N OF 16N
ON THE SW PORTION OF AN ATLC RIDGE AND AHEAD OF THE TROF IN THE
GULF. SPEED CONFLUENCE ASSOCIATED WITH THIS IS GENERATING A
REGION OF SCATTERED LOW TO MID CLOUDS WITH POSSIBLE EMBEDDED
LIGHT SHOWERS OFFSHORE NICARAGUA. HIGH PRES N OF THE AREA WILL
MAINTAIN MODERATE TO STRONG TRADES THROUGHOUT MUCH OF THE
CARIBBEAN WITH GALE CONDITIONS OVER THE SW PORTION THROUGH WED
MORNING.

THE ATLANTIC OCEAN...
COMPLEX FRONTAL PATTERN AS DESCRIBED IN GULF SECTION ALSO
AFFECTING THE SW N ATLC. A STATIONARY FRONT THAT SEEMS TO MARK A
DEWPOINT BOUNDARY THE BEST EXTENDS E FROM THE LOW OVER N FLORIDA
TO 32N72W. A TROUGH AHEAD OF THIS IS ALONG 29N69W 26N76W. THE
UNSTABLE ENVIRONMENT IN THE WRN ATLC HAS NUMEROUS MODERATE
CONVECTION N OF 24N BETWEEN 67W-76W. THIS IS ALSO BEING
SUPPORTING BY UPPER DIFFLUENCE BETWEEN A SMALL SHORTWAVE TROUGH
ZIPPING E AWAY FROM FLORIDA...AND THE RIDGING EXTENDING NE
THROUGH THE CENTRAL ATLC FROM THE CARIBBEAN. OVERALL
THOUGH...LARGE SCALE UPPER FLOW IN THE W AND CENTRAL ATLC IS
ZONAL. THIS IS ADVECTING THE MOISTURE OVER THE AFOREMENTIONED
CONVECTION N OF 24N EWARD TO NEAR 40W. A DISSIPATING COLD
FRONT/TROUGH ENTERS THE AREA NEAR 32N30W AND EXTENDS SW TO
24N50W. IT APPEARS AS IF THE 1033 MB HIGH PRES N OF MADEIRA
ISLAND IS BUSTING THROUGH THIS BOUNDARY...SO LOOK FOR THIS OLD
BOUNDARY TO CONTINUE DISSIPATING. THE HIGH IS PRODUCING MODERATE
TO STRONG NE TO E WINDS AND FAIR WEATHER OVER MUCH OF THE E
ATLC...AND THIS IS EXPECTED TO PERSIST OVER THE NEXT COUPLE OF
DAYS. UPPER PATTERN OVER THE E ATLC GENERALLY DOMINATED BY LARGE
SCALE RIDGING...THOUGH A MID LEVEL TROUGH IS JUST OFFSHORE
AFRICA FROM 15N-25N E OF 25W THAT IS SURROUNDED BY VERY DRY AIR.

$$
WILLIS




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