[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172325
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE APR 17 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
2215 UTC.

...THE ITCZ...
ITCZ AXIS EXTENDS FROM 7N12W 4N20W CROSSING THE EQUATOR AT 29W
INTO NE BRAZIL NEAR 3N40W. CLUSTERS OF MODERATE/ISOLATED STRONG
CONVECTION ARE WITHIN 60 NM EITHER SIDE OF THE AXIS BETWEEN THE
AFRICAN COAST AND 16W. ISOLATED MODERATE CONVECTION IS WITHIN 60
NM OF THE AXIS BETWEEN 25W-28W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT EXTENDS FROM A 1006 MB LOW CENTERED OVER THE
TEXAS/NEW MEXICO BORDER THROUGH CENTRAL TEXAS AND INTO N MEXICO
NEAR 27N105W. A PRE-FRONTAL TROUGH EXTENDING FROM THE SFC LOW
THROUGH CENTRAL MEXICO NEAR 18N99W IS ADVECTING LOW/MID LEVEL
MOISTURE WITH POSSIBLE SHOWERS OVER THE W GULF FROM THE TEXAS/N
MEXICO COASTLINES. THE FRONT IS EXPECTED TO ENTER THE GULF EARLY
WED AND MOVE RAPIDLY THROUGH THE STRAITS OF FLORIDA AND THE
YUCATAN CHANNEL BY LATE THURS. MODERATE TO STRONG SLY WINDS
AHEAD OF THE TROUGH WILL WEAKEN AND BECOME WLY TO NLY FOLLOWING
THE FRONTAL PASSAGE. ELSEWHERE...A WEAK 1018MB HIGH SOUTH OF
LOUISIANA CONTINUES TO MAINTAIN A DRY AND STABLE AIRMASS OVER
THE E/CENTRAL GULF. THIS HIGH IS PRODUCING NLY FLOW ACROSS THE
FAR E GULF AND FLORIDA PENINSULA INTO CUBA AND THE WESTERN
CARIBBEAN. BROKEN FAIR WEATHER STRATOCUMULUS CLOUDS COVER THE
S-CENTRAL PORTION OF THE GULF. ALOFT...GENERALLY ZONAL FLOW
DOMINATES THE ENTIRE GULF TRANSPORTING A PLUME OF UPPER LEVEL
MOISTURE NEWD ACROSS N-CENTRAL MEXICO...SOUTH TEXAS AND THE
NORTHERN GULF WATERS.

CARIBBEAN SEA...
THE STRONG COLD FRONT THAT HAS AFFECTED THE FORECAST AREA HAS
WEAKENED OVER THE CARIBBEAN SEA BECOMING A TROUGH NEAR 19N74W
AND EXTENDS SW INTO COSTA RICA. A NARROW BAND OF LOW/MID LEVEL
CLOUDS WITH POSSIBLE SHOWERS IS CENTERED AROUND THE TROUGH. COLD
AIR STRATOCUMULUS CLOUDS COVER THE YUCATAN CHANNEL AND THE NW
CARIBBEAN. AN UPPER HIGH NEAR 16N84W EXTENDS A RIDGE EWD TO THE
LESSER ANTILLES...GIVING THE AREA DRY AIR AND MODERATE TO STRONG
SUBSIDENCE. THE TRADES REMAIN LIGHT TO MODERATE ACROSS MUCH OF
THE AREA DUE TO THE WEAK PRES GRADIENT.

ATLANTIC OCEAN...
A STRONG COLD FRONT IS WELL DEFINED OVER THE ATLC ENTERING THE
AREA NEAR 32N55W AND CONTINUING SW TO HISPANIOLA. THE COLD FRONT
CONTINUES TO PRODUCE GALE FORCE WINDS AND HAZARDOUS MARINE
CONDITIONS...PARTICULARLY N OF 25N WITHIN 240 NM AHEAD OF THE
FRONT...AND N OF 27N BEHIND THE FRONT TO 77W. A BROAD BAND OF
MOISTURE WITH EMBEDDED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS EXTENDS 100-200 NM AHEAD OF THE FRONT. A 15Z
QUIKSCAT PASS SHOWS 25-35 KT ON EITHER SIDE OF THE FRONT
HOWEVER...WINDS OVER THE W ATLC WILL DIMINISH TO 15 KT AS THE
FRONT CONTINUES TO MOVE EWD. A TROUGH ENTERS THE REGION NEAR
31N28W EXTENDING FROM A COLD FRONT AND SFC LOW WELL NORTH OF THE
AREA. THE TROUGH CONTINUES SW TO NEAR 24N39W WITH A BAND OF
LOW/MID LEVEL MOISTURE EXTENDING 60-90 NM AHEAD OF THE TROUGH. A
SFC HIGH REMAINS E OF THE TROUGH CENTERED NEAR 25N25W EXTENDING
A RIDGE OVER THE E-CENTRAL ATLC. ALOFT...A DEEP LAYERED TROUGH
IS SUPPORTING THE FRONTAL BOUNDARY OVER THE W ATLC. THE
MID/UPPER LEVEL RIDGE OVER THE CARIBBEAN EXTENDS NE INTO THE
CENTRAL ATLC THROUGH THE LEEWARD ISLANDS. FARTHER E...ANOTHER
UPPER LEVEL TROUGH DOMINATES THE E ATLC WITH THE AXIS EXTENDING
SW TO THE DEEP TROPICS NEAR 8N49W. STRONG SWLY WINDS AHEAD OF
THE TROUGH ARE TRANSPORTING UPPER LEVEL MOISTURE FROM N SOUTH
AMERICA NEWD TO W AFRICA JUST N OF THE CAPE VERDE ISLANDS.

$$
RJW


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