000 AXNT20 KNHC 291756 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON SEP 29 2008 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND 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. ...SPECIAL FEATURES... SUBTROPICAL STORM LAURA IS CENTERED NEAR 37.4N 47.8W AT 29/1500 UTC OR ABOUT 600 NM SOUTH-SOUTHEAST OF CAPE RACE NEWFOUNDLAND MOVING WNW AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO 60 KT. LAURA IS EXPECTED TO GRADUALLY TURN TOWARD THE NORTHWEST AND THEN TOWARD THE NORTH WITH AN INCREASE IN FORWARD SPEED BY TUESDAY. TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 240 NM FROM THE CENTER WITH SCATTERED MODERATE CONVECTION LOCATED WITHIN 200 NM OF THE CENTER IN THE ERN SEMICIRCLE. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT2/ WTNT32 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 26W/27W S OF 15N MOVING W NEAR 10 KT. BROAD CYCLONIC CURVATURE IS OBSERVED ON VISIBLE SATELLITE IMAGERY CENTERED NEAR 10N. CLUSTERS OF SCATTERED MODERATE/ ISOLATED STRONG CONVECTION ARE FROM 10N-15N BETWEEN 26W-29W. SCATTERED MODERATE CONVECTION IS FROM 4N-15N BETWEEN 25W-30W. A TROPICAL WAVE IS ALONG 42W BETWEEN 10N-20N MOVING W NEAR 5-10 KT. A BROAD LOW-LEVEL CYCLONIC CIRCULATION IS VISIBLE ON SATELLITE IMAGERY NORTH OF 13N. NO ASSOCIATED SHOWERS OR DEEP CONVECTION WITH THE WAVE AS IT MOVES BENEATH STRONG SWLY UPPER FLOW. A TROPICAL WAVE IS ALONG 56W S OF 16N MOVING W NEAR 5-10 KT. AN UPPER-LEVEL LOW CENTERED EAST OF THE LEEWARD ISLANDS IS PRODUCING MODERATE TO STRONG UPPER-LEVEL SWLY FLOW OVER THE WAVE. STRONG SUBSIDENCE ALOFT IS PREVENTING ANY SHOWERS OR DEEP CONVECTION FROM DEVELOPING IN THE VICINITY OF THE WAVE. ...THE ITCZ... THE ITCZ AXIS IS ANALYZED ALONG 12N15W 11N25W 10N29W 6N36W 8N45W 7N53W. IN ADDITION TO CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS FROM 4N-8N BETWEEN 17W-20W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N BETWEEN 34W-39W. ...DISCUSSION... GULF OF MEXICO... A 1010 MB LOW PRESSURE SYSTEM IS LOCATED IN THE S/CENTRAL GULF OF MEXICO NEAR 23N89W. A SURFACE TROUGH EXTENDS FROM ACROSS CENTRAL FLORIDA NEAR CAPE CANAVERAL TO THE LOW CENTER SW TO NEAR CAMPECHE MEXICO. NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS ARE OVER THE SE GULF S OF 28N AND W OF 90W. THE LOW IS FORECAST TO MOVE NE...TRACKING ACROSS THE SRN FLORIDA PENINSULA TUESDAY. E TO SE WINDS OF 10-15 KT ARE OBSERVED IN THE SE GULF AHEAD OF THE SURFACE TROUGH. A STRONG PRESSURE GRADIENT BETWEEN THIS LOW PRESSURE AREA AND HIGHER PRESSURE OVER THE WRN GULF AND NE MEXICO IS PRODUCING NLY WINDS 15-20 KT OVER THE SW GULF AND THE BAY OF CAMPECHE. NE WINDS OF 10-15 KT COVER THE REMAINDER OF THE GULF N OF 28N. ALOFT...A MID/UPPER LEVEL TROUGH IS MOVING OVER THE WRN ATLC WITH ITS AXIS ALONG 93W. UPPER-LEVEL SWLY WINDS EAST OF THIS TROUGH ARE TRANSPORTING ABUNDANT UPPER LEVEL MOISTURE ACROSS THE SE GULF TO AID IN SUPPORTING THE PREVIOUSLY MENTIONED SHOWERS AND THUNDERSTORM ACTIVITY. CARIBBEAN SEA... UPPER LEVEL DIVERGENT FLOW BETWEEN THE TROUGH OVER THE WRN GULF OF MEXICO AND UPPER LEVEL RIDGING ACROSS THE NRN CARIBBEAN EXTENDING FROM AN UPPER LEVEL HIGH CENTERED OVER THE W ATLC NE OF THE BAHAMAS IS GENERATING WIDELY SCATTERED SHOWERS AND TSTMS ACROSS THE CENTRAL AND WRN CARIBBEAN W OF 74W. THE ITCZ AXIS EXTENDS FROM THE ERN PACIFIC REGION ACROSS THE SW CARIBBEAN SEA ALONG 10N WHICH IS ALSO AIDING IN DEVELOPMENT OF SCATTERED SHOWERS AND TSTMS S OF 13N AND W OF 80W...INCLUDING COASTAL NICARAGUA AND COSTA RICA. THE ERN CARIBBEAN REMAINS UNDER MOSTLY CLEAR CONDITIONS DUE TO A DRY AND STABLE AIRMASS ALOFT. MODERATE TRADE WINDS PERSIST THROUGHOUT THE CARIBBEAN THIS AFTERNOON. ATLANTIC OCEAN... SUBTROPICAL STORM LAURA IS LOCATED IN THE N/CENTRAL ATLANTIC... SEE SPECIAL FEATURES SECTION ABOVE. ABUNDANT UPPER-LEVEL MOISTURE CONTINUES TO STREAM ACROSS THE FLORIDA PENINSULA AND OVER THE W ATLC WATERS DUE TO STRONG SWLY FLOW AHEAD OF AN UPPER TROUGH OVER THE GULF OF MEXICO. A SURFACE TROUGH EXTENDS FROM NEAR 30N78W TO CAPE CANAVERAL FLORIDA AND ACROSS CENTRAL FLORIDA. SCATTERED SHOWERS WITH EMBEDDED TSTMS ARE ACROSS THE W ATLC WATERS FROM 26N-32N BETWEEN 74W-80W. AN UPPER-LEVEL HIGH IS CENTERED NE OF THE BAHAMAS NEAR 24N72W AND IS PROVIDING MODERATE TO STRONG SUBSIDENCE/DRY AIR S OF 26N AND W OF 58W. THIS TRANSLATES TO THE SURFACE AS A 1017 MB HIGH...CENTERED NEAR 26N67W. THE ERN ATLANTIC IS DOMINATED BY A SURFACE HIGH PRESSURE RIDGE EXTENDING SWD FROM THE AZORES TO NEAR 20N. ALOFT...A TROUGH CONNECTS AN UPPER LOW NEAR 36N42W TO A SECOND UPPER LOW EAST OF THE LEEWARD ISLANDS CENTERED NEAR 17N58W. WIDELY SCATTERED SHOWERS ARE FROM 27N-32N BETWEEN 37W-43W E OF THE UPPER TROUGHING. A UPPER RIDGE COVERS THE REMAINDER OF THE ERN ATLC E OF 50W AND IS CENTERED ON AN UPPER HIGH NEAR 18N23W. UPPER LEVEL FLOW AROUND THIS RIDGE CONTINUES TO ENHANCE CONVECTION ALONG THE ITCZ EAST OF 40W. $$ HUFFMAN