[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 092356
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED AUG 09 2006

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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2315 UTC.

...SPECIAL FEATURE...

A STRONG WELL DEFINED TROPICAL WAVE APPROACHING THE WINDWARD
ISLANDS ALONG 58W IS MOVING RATHER QUICKLY WESTWARD NEAR 20 KT.
EARLIER THIS AFTERNOON...THE AIR FORCE RESERVE HURRICANE HUNTER
AIRCRAFT INVESTIGATED THIS SYSTEM AND COULD NOT FIND A CENTER OF
CIRCULATION. THIS WAVE IS STILL SHOWING SOME SIGNS OF
ORGANIZATION WITH A MID-LEVEL CIRCULATION LOCATED ON OR JUST
AHEAD OF THE WAVE AXIS NEAR 14N. THIS WAVE HAS A BROAD BUT WELL
DEFINED INVERTED V-SHAPE. MUCH OF THE WEATHER ASSOCIATED WITH
THIS FEATURE IS WELL AHEAD OF THE ANALYZED WAVE AXIS AND
MID-LEVEL CIRCULATION FROM 14N-17N BETWEEN 60W-63W AND APPEARS
TO BE RACING FARTHER WEST. REGARDLESS OF TROPICAL CYCLONE
DEVELOPMENT...THE SYSTEM WILL CONTINUE TO SPREAD SHOWERS AND
THUNDERSTORMS WITH GUSTY WINDS TO TROPICAL STORM FORCE IN
SQUALLS OVER PORTIONS OF THE LESSER ANTILLES TONIGHT....AND THE
VIRGIN ISLANDS AND PUERTO RICO ON THURSDAY.


...TROPICAL WAVES...

A TROPICAL WAVE HAS BEEN REPOSITIONED SLIGHTLY ALONG 36W/37W
SOUTH OF 19N MOVING WEST 15 KT. THIS LOCATION IS BASED ON
VISIBLE AND SHORTWAVE IR SATELLITE IMAGERY WHERE CLEAR CYCLONIC
CURVATURE IS EVIDENT. DESPITE THE FAIR AMOUNT OF TURNING
ASSOCIATED WITH THE WAVE...DRY AIR IS SURROUNDING THE FEATURE
LIMITING ANY SHOWER ACTIVITY TO ISOLATED AND WEAK.

A WESTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 86W SOUTH OF 24N
MOVING WEST 15-20 KT. THIS WAVE IS INTERACTING WITH AN UPPER LOW
IN THE GULF TO PRODUCE SCATTERED MODERATE CONVECTION OVER PARTS
OF CENTRAL AMERICA AND S MEXICO. SEE THE GULF OF MEXICO AND
CARIBBEAN SECTIONS FOR MORE DETAILS.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N15W 11N35W 13N54W TO VENEZUELA
NEAR 10N66W. THE AXIS IS RATHER QUIET THIS EVENING WITH ONLY
ISOLATED SHOWERS AND TSTMS E OF 22W WITHIN 180 NM EITHER SIDE
OF THE AXIS LIKELY AHEAD OF THE NEXT TROPICAL WAVE. SCATTERED
SHOWERS AND TSTMS ARE WITHIN 60 NM OF THE AXIS BETWEEN 43W-48W.

...DISCUSSION...
THE GULF OF MEXICO...
A WELL DEFINED MID-UPPER LEVEL LOW HAS TRACKED WWARD ACROSS
FLORIDA INTO THE E GULF CENTERED NEAR 26N86W. UPPER RIDGING
DOMINATES THE SOUTHERN U.S. WITH THE HIGH CENTER OVER N GEORGIA
PRODUCING A LARGE AREA OF 100 F DEGREE TEMPS ACROSS THE S/CNTRL
U.S. UPPER DIFFLUENCE BETWEEN THESE FEATURES IS GENERATING AN
AREA OF NUMEROUS SHOWERS AND TSTMS N OF 27N BETWEEN 89W-92W.
THIS UPPER LOW IS INTERACTING WITH A TROPICAL WAVE IN THE W
CARIBBEAN ALONG 86W TO PRODUCE SCATTERED SHOWERS ACROSS THE
CENTRAL AND E GULF S OF 27N BETWEEN 82W-92W. THE ACTIVITY IS NOT
AS ACTIVE AS IT WAS YESTERDAY WHEN THE INTERACTION WAS OVER THE
W BAHAMAS AND S FLORIDA. A WEAK SFC TROUGH IS IN THE SW GULF
FROM 18N94W TO 23N96W. POCKETS OF MODERATE CONVECTION ARE ALONG
THE COAST OF MEXICO...MAINLY INLAND...W OF 96W S OF 24N.  A WEAK
SFC PRES GRAD LIES ACROSS THE REGION PRODUCING LIGHT E-SE WINDS.
SIMILAR CONDITIONS ARE EXPECTED OVER THE NEXT COUPLE OF
DAYS...WHILE THE UPPER LOW MOVES INTO THE WRN GULF.

THE CARIBBEAN SEA...
THE MAIN FEATURE IN THE REGION IS THE STRONG TROPICAL WAVE ALONG
57W/58W AND 1010 MB LOW ALONG THE WAVE NEAR 13N. SCATTERED
MODERATE CONVECTION HAS SPREAD ACROSS THE LEEWARD
ISLANDS...NAMELY FROM 14N-17N BETWEEN 59W-63W. FOR MORE
DETAILS...SEE THE SPECIAL FEATURE SECTION ABOVE. ELSEWHERE...THE
UPPER LOW IN THE GULF OF MEXICO HAS TROUGHING THAT STRETCHES TO
19N85W. THIS UPPER LOW INTERACTING WITH A TROPICAL WAVE ALONG
86W IS TRIGGERING SCATTERED SHOWERS AND TSTMS ACROSS
GUATEMALA...BELIZE AND THE YUCATAN PENINSULA. UPPER DIFFLUENCE
BETWEEN AN UPPER HIGH N OF PANAMA NEAR 11N81W AND THE UPPER
TROUGHING IN THE NW CARIBBEAN IS GENERATING A LINE OF SHOWERS
AND TSTMS FROM 14N-20N BETWEEN 76W-79W. EARLIER THIS
AFTERNOON...SHOWERS AND TSTMS WERE MUCH MORE WIDESPREAD AND
STRETCHED ACROSS A GOOD PORTION OF THE CENTRAL CARIBBEAN WATERS
BETWEEN 14N-17N IN A DIFFLUENT ZONE. HOWEVER...THIS ACTIVITY HAS
BECOME MUCH MORE ISOLATED BETWEEN 64W-75W OVER THE PAST FEW
HOURS. THE REMAINDER OF THE CARIBBEAN IS UNDER BROAD UPPER LEVEL
NE/E FLOW WITH AN UPPER LOW 100 NM TO THE NE OF THE NRN LEEWARD
ISLANDS. 15 TO 25 KT TRADE FLOW CONTINUES TO DOMINATE MUCH OF
THE CARIBBEAN THIS EVENING...WITH THE STRONGEST WINDS GENERALLY
BETWEEN THE COLOMBIAN COAST AND HISPANIOLA ...WHERE THE SFC PRES
GRAD IS THE TIGHTEST.  MOISTURE ASSOCIATED WITH THE SPECIAL
FEATURE WILL CONTINUE TO SPREAD EWARD TOWARDS THE CENTRAL
CARIBBEAN OVER THE NEXT DAY OR TWO.

THE ATLANTIC OCEAN...
THERE ARE NOT ANY SIGNIFICANT UPPER LEVEL FEATURES IN THE
CENTRAL AND WRN ATLC THIS EVENING. A LONGWAVE TROF IS WELL OFF
THE E COAST OF THE U.S. WITH AN ASSOCIATED SLOWING SFC FRONT
JUST N OF THE DISCUSSION AREA. A STRONG UPPER RIDGE COVERS THE
SE U.S. AND A WEAK DRY UPPER LEVEL LOW IS ABOUT 100 NM TO THE N
OF THE NRN LEEWARD ISLANDS CENTERED NEAR 20N62W. N/NE FLOW
DOMINATES MUCH OF THE SW ATLC BETWEEN THE FLORIDA COAST AND 62W
BETWEEN THESE UPPER LEVEL FEATURES. A BROAD AREA OF UPPER LEVEL
ANTICYCLONIC FLOW IS SEEN ON WV IMAGERY FROM 5N TO 30N BETWEEN
THE AFRICAN COAST AND 50W...WITH THE HIGH CENTER ESTIMATED TO BE
NEAR 17N31W. AN UPPER TROUGH CLIPS THE AREA N OF 30N BETWEEN
27W-37W. PLENTY OF DRY/STABLE MID-UPPER LEVEL AIR COVERS THE
MAJORITY OF THE AREA KEEPING CONDITIONS RATHER QUIET. AT THE
SFC...WEAK HIGH PRES RIDGING EXTENDS ACROSS MUCH OF THE AREA
WITH A 1022 MB HIGH CENTER ANALYZED NEAR 27N70W AND A 1021 MB
CENTER NEAR 26N55W. LITTLE CHANGE IN THE OVERALL SFC PATTERN IS
EXPECTED OVER THE NEXT COUPLE OF DAYS.

$$
CANGIALOSI




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