[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 052344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU JUL 05 2007

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
2315 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS TILTED FROM 16N22W TO 4N30W MOVING W 10-15
KT. A LARGER SCALE INVERTED V-TYPE STRUCTURE IS APPARENT FURTHER
TO THE NE...REACHING THE CAPE VERDE ISLANDS. MINIMAL SHOWER
ACTIVITY IS ASSOCIATED WITH THIS WAVE THAT IS GENERATING SOME
CLOUDINESS OVER THESE ISLANDS.

AS OF 2100 UTC...A 1014 MB LOW PRES SYSTEM LOCATED NEAR 11N50W
OR ABOUT 650 NM EAST OF THE SOUTHERN WINDWARD ISLANDS IS
MOVING W AT 10-15 KT. THIS WEAK LOW CONTINUES TO HAVE MINIMAL
TSTM ACTIVITY AND ENVIRONMENTAL CONDITIONS ARE BECOMING LESS
FAVORABLE FOR DEVELOPMENT. THE LOW IS EMBEDDED IN A TROPICAL
WAVE LOCATED ALONG 49W/50W. MOISTURE FROM THIS LOW/TROPICAL WAVE
SHOULD AFFECT THE WINDWARD ISLANDS SAT.

A TROPICAL WAVE IS MOVING ACROSS THE E CARIBBEAN WITH THE AXIS
ALONG 63W. THE WAVE IS PRODUCING SOME SHOWER ACTIVITY OVER THE
WINDWARD ISLANDS AND NE VENEZUELA. TRINIDAD AND TOBAGO REPORTED
MAINLY LIGHT TO MODERATE SHOWERS AND TSTMS WITH THE PASSAGE OF
THE WAVE. SIMILAR ACTIVITY AND GUSTY WINDS AFFECTED THE NORTHERN
LEEWARD ISLANDS. THIS WAVE WILL MOVE ACROSS THE VIRGIN ISLANDS
AND PUERTO RICO TONIGHT REACHING DOMINICAN REPUBLIC TOMORROW
MORNING WITH SOME INCREASE IN SHOWER ACTIVITY. A WIND SURGE WILL
FOLLOW THE WAVE. THE SAN JUAN DOPPLER RADAR IS SHOWING SCATTERED
SHOWERS MOVING FROM E TO W ACROSS THE VIRGIN ISLANDS.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 8N13W 7N25W 4N36W 6N47W 8N60W.
SCATTERED SHOWERS AND TSTMS ARE WITHIN 120 NM S OF THE AXIS
BETWEEN 17W-22W.

...DISCUSSION...
GULF OF MEXICO...
A LINE OF SHOWERS WITH EMBEDDED TSTMS IS ACROSS THE NW CORNER OF
THE GULF. SIMILAR ACTIVITY IS SEEN OVER THE N GULF WATERS AND
NEAR THE W COAST OF FLORIDA. AN ILL-DEFINED SURFACE LOW PRESSURE
AREA LOCATED OVER FLORIDA NEAR 29N82W IS PRODUCING A LARGE AREA
OF DISORGANIZED SHOWERS AND THUNDERSTORMS ACROSS THE FLORIDA
PENINSULA AND COASTAL WATERS. A WEAK TROUGH EXTENDS FROM THIS
SFC LOW ACROSS THE FLORIDA PENINSULA AND THE SE PORTION OF THE
GULF. UPPER DIFFLUENT ASSOCIATED WITH AN UPPER HIGH OVER THE
NORTH-CENTRAL GULF IS SUPPORTING ALL THIS CONVECTIVE ACTIVITY.
AN UPPER LOW IS SPINNING OVER MEXICO AND GUATEMALA BRINGING
TROPICAL MOISTURE FROM THE SW CARIBBEAN INTO THE YUCATAN
PENINSULA AND THE GULF. TIGHTENED PRES GRADIENT BETWEEN HIGH
PRES OVER THE SE STATES AND LOWER PRES OVER TEXAS/MEXICO IS
PRODUCING MODERATE SELY WINDS ACROSS THE SW GULF. WEAK HIGH PRES
WILL MEANDER OVER THE CENTRAL WATERS THROUGH SUN. ACCORDING TO
THE GFS MODEL...THE LOW OVER FLORIDA WILL WEAKEN TONIGHT BUT A
TROUGH WILL PERSIST OVER THE AREA.

CARIBBEAN SEA...
DRY AIR ALOFT ADVECTED FROM THE TROPICAL ATLC DOMINATES A GOOD
PORTION OF THE BASIN GIVING THE AREA MOSTLY FAIR WEATHER. THE
THE EXCEPTION IS THE E CARIBBEAN WHERE THERE IS A TROPICAL WAVE
MOVING WWD. SEE ABOVE. THE UPPER ATMOSPHERE IS MORE MOIST
FURTHER W SUPPORTED BY AN UPPER LOW SPINNING OVER MEXICO AND
GUATEMALA. CLUSTERS OF MODERATE CONVECTION ARE OVER COSTA RICA
AND PANAMA DUE TO THE CLOSE PROXIMITY OF THE EPAC ITCZ.
SCATTERED SHOWERS AND ISOLATED TSTMS ARE FOUND OVER NORTHERN
CENTRAL AMERICA. AFTERNOON HEAT INDUCED SHOWERS AND TSTMS ARE
OVER CUBA MODERATE TO STRONG ELY TRADE WINDS CONTINUES TO AFFECT
THE AREA PARTICULARLY THE SOUTH-CENTRAL CARIBBEAN NEAR THE COAST
OF COLOMBIA. THE ATLC RIDGE N OF REGION WILL MAINTAIN ELY TRADES
THROUGH THE UPCOMING WEEKEND.

ATLANTIC OCEAN...
AN ILL-DEFINED SURFACE LOW PRESSURE AREA LOCATED OVER THE
FLORIDA PENINSULA NEAR 29N82W IS PRODUCING A LARGE AREA OF
DISORGANIZED SHOWERS AND THUNDERSTORMS. ENVIRONMENTAL CONDITIONS
ACROSS THE AREA DO NOT SUPPORT TROPICAL CYCLONE DEVELOPMENT.
HOWEVER...PERIODS OF LOCALLY HEAVY RAINFALL ARE POSSIBLE OVER
PORTIONS OF FLORIDA AND THE BAHAMA ISLANDS OVER THE NEXT COUPLE
OF DAYS. A WARM FRONT EXTENDS EWD FROM THIS LOW ALONG 30N77W
29N71W. A STATIONARY FRONT CLIPS THE AREA ALONG 30N BETWEEN 55W
AND 65W. MODERATE CONVECTION IS SEEN BETWEEN THE WARM FRONT AND
THE NW BAHAMAS AND ALONG THE E FLORIDA COAST. FARTHER E...THERE
HAS BEEN LITTLE CHANGE OVER THE PAST FEW DAYS WITH RIDGING STILL
DOMINATING BOTH AT THE SFC AND ALOFT. THE AZORES HIGH WITH 1029
MB CENTER IS ANALYZED NEAR 37N27W. THIS HIGH IS PRODUCING A
LARGE AREA OF MODERATE TRADES ACROSS THE ATLC. STRONG NLY WINDS
ARE NEAR THE AFRICAN COAST DUE TO THE TIGHTENING PRES GRADIENT
BETWEEN THE HIGH AND INVERTED TROUGHING OVER THE CONTINENT. A
SERIES OF UPPER HIGHS ARE PROVIDING A VERY STABLE AIRMASS ACROSS
THE CENTRAL AND E ATLC WITH ONLY LOW-LEVEL STABLE STRATOCUMULUS
CLOUDS SEEN ACROSS MUCH OF THE FORECAST REGION.

$$
GR






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