[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 071746
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON MAY 07 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
1715 UTC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 7N12W 3N20W 2N30W...AND ALONG THE
EQUATOR BETWEEN 40W-52W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 100 NM S OF THE AXIS BETWEEN 18W-21W... AND
WITHIN 80 NM NORTH OF THE AXIS BETWEEN 24W-30W. SCATTERED
MODERATE CONVECTION IS 1S-2N BETWEEN WEST OF 38W.

...DISCUSSION...

GULF OF MEXICO...
A BACKDOOR COLD FRONT ASSOCIATED WITH THE STRONG LOW PRESSURE
CENTER OFF THE SE U.S. CONTINUES TO PUSH THROUGH THE EASTERN
GULF WITH INCREASING WINDS AND SEAS. AS OF 15Z...THE FRONTAL
SYSTEM ENTERS THE AREA THROUGH THE STRAITS OF FLORIDA CONTINUING
NW TO SE LOUISIANA. THE FRONTAL BOUNDARY IS VERY WELL DEFINED ON
SAT IMAGERY WHERE A 125 NM WIDE BAND OF MULTILAYERED CLOUDS WITH
EMBEDDED SHOWERS IS SEEN...BUT ESPECIALLY ACROSS THE ATLC OCEAN.
EARLIER QUIKSCAT PASS SHOWED NE TO E WINDS OF 20-30 KT BEHIND
THE FRONT AND 10-20 KT E TO SE WINDS AHEAD OF THE FRONT OVER THE
REST OF THE GULF. A MOIST ONSHORE FLOW IS PRODUCING BROKEN LOW
CLOUDS ALONG TEXAS/MEXICO COASTS. UPPER RIDGING IS OVER THE WRN
GULF WHICH IS TRANSPORTING UPPER LEVEL MOISTURE EWD. TROUGHING
ASSOCIATED WITH DEEP LAYERED LOW LOCATED SE OF CAPE HATTERAS
EXTENDS INTO FLORIDA AND THE EASTERN GULF GIVING THE AREA A NW
WIND FLOW. BRISK NE-E WINDS EXPECTED IN THE E AND CENTRAL GULF
THROUGH TONIGHT...VEERING MORE SE IN THE WRN PORTION. THE
BACKDOOR FRONT IS FORECAST TO GRADUALLY DISSIPATE TONIGHT.

CARIBBEAN SEA...
THE SFC PRES PATTERN IN THE CARIBBEAN SEA REMAINS WEAK DUE TO
LOW PRES IN THE SW N ATLC. A QUIKSCAT PASS FROM THIS MORNING
SHOWED E TO NE TRADE WINDS IN THE 10-15 KT RANGE. LIGHTER THAN
NORMAL TRADES WILL CONTINUE THROUGH MIDWEEK DUE TO THE PRESENCE
OF THE STORM SYSTEM OFF THE SOUTHEAST U.S.. UPPER DIFFLUENCE AND
THE CLOSE PROXIMITY OF THE EPAC ITCZ ARE ENHANCING CLUSTERS OF
MODERATE TO ISOLATED STRONG CONVECTION OVER PANAMA...COSTA RICA
AND THE SW CARIBBEAN. A 1007 MB SFC LOW IS OVER NORTHERN
COLOMBIA IS ALSO GENERATING SOME SHOWER/TSTM ACTIVITY. UPPER SW
FLOW BETWEEN TROUGHING OVER THE WRN CARIB AND RIDGING OVER THE
ERN CARIB IS SPREADING UPPER LEVEL MOISTURE/HIGH CLOUDS NE
THROUGH THE CENTRAL AND ERN PORTIONS OF THE BASIN INTO THE
TROPICAL NORTH ATLC.

WESTERN ATLANTIC...
ATTENTION REMAINS FOCUSED ON A RAPIDLY STRENGTHENING LOW PRES
CENTER OFF THE SE OF UNITED STATES. A 998 MB LOW IS ANALYZED ON
THE 12Z MAP NEAR 32N73W. THIS STRONG LOW WILL MOVE INTO OUR
FORECAST AREA LATER THIS AFTERNOON. THE BACK DOOR COLD FRONT
ASSOCIATED WITH IT ENTERS THE AREA NEAR 31N38W THEN CONTINUES SW
CROSSING THE CENTRAL BAHAMAS AND THE STRAITS OF FLORIDA INTO THE
GULF OF MEXICO. LATEST VIS SAT IMAGERY SHOWS THE LEADING EDGE OF
THE FRONTAL BOUNDARY OVER W-CENTRAL CUBA. CURRENTLY...THE MAIN
IMPACT WITH THIS STORM SYSTEM IS THE STRONG WINDS AND LARGE SEAS
AS A VERY TIGHT PRES GRADIENT HAS SET UP BETWEEN THE LOW AND
STRONG HIGH PRES OVER THE MID-ATLANTIC STATES. SEVERAL ADVISORIES
AND WATCHES/WARNINGS HAVE BEEN POSTED ALONG THE COAST FROM SOUTH
FLORIDA TO BEYOND THE CAROLINAS WHERE ROUGH SURF AND VERY
DANGEROUS RIP CURRENTS ARE EXPECTED. AS THE LOW APPROACHES THE
SE COAST OF U.S. TUE THROUGH WED...RAINFALL WILL BE ALSO A
CONCERN. FOR MORE DETAILS...SEE STATEMENTS FROM LOCAL FORECAST
OFFICES. FARTHER E...A 1011 MB LOW LOCATED NEAR 30N60W WILL BE
ABSORBED BY THE FRONTAL SYSTEM EXTENDING JUST NORTH OF IT.
SCATTERED SHOWERS/TSTMS ARE MAINLY E OF THE LOW N OF 28N BETWEEN
52-58W. THE REMAINDER OF THE ATLC OCEAN IN UNDER THE INFLUENCE
OF THE BERMUDA-AZORES HIGH. THIS FEATURE IS PRODUCING A LARGE
AREA OF MODERATE TO FRESH TRADES...STRONGEST E OF 25W WHERE THE
PRES GRADIENT IS TIGHTENED DUE TO LOWER PRES OVER AFRICA.
PATCHES OF LOW LEVEL MOISTURE ARE ACROSS THE AREA. AN UPPER LOW
IS NEAR 31N22W WITH A TROUGH EXTENDING SW TO 17N31W...BUT DOES
NOT APPEAR TO BE GENERATING SIGNIFICANT WEATHER.

$$
GR






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