000 AXNT20 KNHC 230007 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE OCT 22 2013 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURE... THE CENTER OF TROPICAL STORM LORENZO AT 22/2100 UTC IS NEAR 29.4N 51.2W. LORENZO IS MOVING EAST AT 7 KNOTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 45 KNOTS WITH GUSTS TO 55 KNOTS. PUBLIC ADVISORIES ON LORENZO ARE ISSUED UNDER WMO HEADER WTNT33 KNHC AND UNDER AWIPS HEADER MIATCPAT3. FORECAST/ADVISORIES ON LORENZO ARE ISSUED UNDER WMO HEADER WTNT23 KNHC AND UNDER AWIPS HEADER MIATCMAT3. NUMEROUS STRONG CONVECTION IS FROM 28N-31N BETWEEN 49W-51W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 27N-32N BETWEEN 48W-52W. ...TROPICAL WAVES... A TROPICAL WAVE EMERGED FROM THE WEST AFRICAN COAST EARLIER TODAY. CURRENTLY ITS AXIS EXTENDS FROM 14N22W TO 06N23W AND IS MOVING WEST AT APPROXIMATELY 10 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATE THE WAVE IS MOSTLY EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT WITH VERY DRY AIR ENGULFING THE NORTHERN SECTOR OF THE WAVE. BOTH DRY AIR AND STRONG DEEP LAYER WESTERLY WIND SHEAR ARE HINDERING DEEP CONVECTION AT THE TIME. SCATTERED SHOWERS ASSOCIATED WITH THE MONSOON TROUGH CONVECTION ARE IN THE SOUTHERN SECTOR OF THE WAVE S OF 09N WITHIN 140 NM EITHER SIDE OF THE AXIS. TROPICAL WAVE AXIS EXTENDS FROM 15N48W TO 07N48W AND IS MOVING WEST AT ABOUT 10-15 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATE THE WAVE IS MOSTLY EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT WITH HIGHER VALUES EAST OF THE WAVE AXIS. THIS WAVE LIES WITHIN THE BASE OF A TILTED UPPER-LEVEL TROUGH WHICH IS SUPPORTING SCATTERED MODERATE CONVECTION FROM 08N-15N BETWEEN 42W-49W. TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS EXTENDING FROM EASTERN CUBA NEAR 21N76W...ACROSS CENTRAL JAMAICA TO CENTRAL PANAMA NEAR 10N79W. THE AXIS IS MOVING W-NW NEAR 10-15 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATE THAT N OF 16N THE WAVE IS GENERALLY EMBEDDED WITHIN A DRY ENVIRONMENT WHILE HIGH MOISTURE IS PRESENT IN THE SOUTHERN SECTOR OF IT. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS MOSTLY ASSOCIATED WITH THE MONSOON TROUGH AND BEING SUPPORTED BY UPPER-LEVEL DIVERGENCE ARE S OF 15N WEST OF THE WAVE AXIS. ISOLATED SHOWERS AND TSTMS ARE WITHIN 50 NM EAST OF THE AXIS FROM 17N-20N. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH PASSES THROUGH THE WEST AFRICAN COAST NEAR 11N16W TO 08N23W TO 06N32W. THE ITCZ CONTINUES FROM 06N32W TO 05N40W TO 07N45W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED MODERATE CONVECTION IS FROM 01N-08N BETWEEN 17W-30W. SIMILAR CONVECTION IS FROM 07N-10N BETWEEN 32W- 36W. ...DISCUSSION... THE GULF OF MEXICO... A MIDDLE TO UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM THE UPPER GREAT LAKES TO THE CENTRAL GULF SUPPORTS A PAIR OF FRONTAL BOUNDARIES. THE FIRST FRONTAL BOUNDARY IS A STATIONARY FRONT THAT EXTENDS ACROSS NORTH-CENTRAL FLORIDA TO 29N82W SW TO 26N90W TO 19N96W. A SECOND STATIONARY FRONT ENTERS THE NE BASIN THROUGH PENSACOLA AND EXTENDS TO 28N87W WHERE IT TRANSITIONS TO A COLD FRONT TO 27N93W 25N97W. WATER VAPOR IMAGERY SHOW THAT DIVERGENT FLOW ASSOCIATED WITH HURRICANE RAYMOND IN THE EAST PACIFIC IS ADVECTING MOISTURE TO THE CENTRAL GULF...WHICH IS SUPPORTING A SWATH OF SHOWERS AND ISOLATED TSTMS EAST OF A LINE FROM 30N86W TO 24N97W AND WEST OF A LINE FROM 27N82W TO 21N86W. WITHIN THE NEXT 24 HOURS...THE COLD FRONT WILL OVERTAKE THE STATIONARY FRONT AND WILL DRIFT E-SE TO EXTEND ACROSS CENTRAL FLORIDA SW TO THE BAY OF CAMPECHE. THE COLD FRONT WILL MOVE ACROSS SOUTHERN FLORIDA EARLY ON THURSDAY AND IS EXPECTED TO MOVE OUT OF THE BASIN DURING THE NIGHT HOURS THAT DAY. THE CARIBBEAN SEA... A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AXIS EXTENDING FROM EASTERN CUBA NEAR 21N76W...ACROSS CENTRAL JAMAICA TO CENTRAL PANAMA NEAR 10N79W. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATE THAT N OF 16N THE WAVE IS GENERALLY EMBEDDED WITHIN A DRY ENVIRONMENT WHILE HIGH MOISTURE IS PRESENT IN THE SOUTHERN SECTOR OF IT. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS MOSTLY ASSOCIATED WITH THE MONSOON TROUGH AND BEING SUPPORTED BY UPPER-LEVEL DIVERGENCE ARE S OF 15N WEST OF THE WAVE AXIS. ISOLATED SHOWERS AND TSTMS ARE WITHIN 50 NM EAST OF THE AXIS FROM 17N-20N. IN THE WESTERN BASIN...MIDDLE TO UPPER LEVEL RIDGING AND DRY AIR SUBSIDENCE DOMINATE TO SUPPORT FAIR WEATHER TONIGHT. A MIDDLE TO UPPER LEVEL ELONGATED LOW EXTENDS FROM THE SOUTHERN BAHAMAS TO THE CENTRAL CARIBBEAN SUPPORTING A SURFACE TROUGH THAT MOVES ACROSS HISPANIOLA FROM 23N67W TO 18N72W. THIS INSTABILITY IN THE ATMOSPHERE IS RESPONSIBLE FOR HEAVY SHOWERS AND TSTMS ACROSS THE ISLAND AND ADJACENT WATERS...INCLUDING THE WINDWARD PASSAGE. MIDDLE TO UPPER LEVEL WIND FLOW AROUND THE EASTERN PERIPHERY OF A RIDGE CENTERED IN THE SW N ATLC IS ADVECTING MOISTURE TO THE SE CARIBBEAN TO SUPPORT RAINSHOWERS IN THE WINDWARD ISLANDS. THE TROPICAL WAVE WILL CONTINUE TO DRIFT WESTWARD AND IS EXPECTED TO BE NEAR 80W ON WEDNESDAY AFTERNOON...MOVING ACROSS CENTRAL AMERICA AT NIGHT THE SAME DAY. A COLD FRONT IS EXPECTED TO ENTER THE NW CARIBBEAN BASIN BY THURSDAY AFTERNOON. HISPANIOLA... A MIDDLE TO UPPER LEVEL ELONGATED LOW EXTENDS FROM THE SOUTHERN BAHAMAS TO THE CENTRAL CARIBBEAN SUPPORTING A SURFACE TROUGH THAT MOVES ACROSS HISPANIOLA FROM 23N67W TO 18N72W. THIS INSTABILITY IN THE ATMOSPHERE IS RESPONSIBLE FOR HEAVY SHOWERS AND TSTMS ACROSS THE ISLAND AND ADJACENT WATERS...INCLUDING THE WINDWARD PASSAGE. SHOWERS WILL CONTINUE TO AFFECT THE ISLAND AND ADJACENT WATERS THROUGH WEDNESDAY NIGHT. THESE SHOWERS WILL SLOWLY DISPLACE W-NW THROUGH TIME AS THE UPPER-LEVEL LOW DRIFTS IN THAT DIRECTION. A DRY AIRMASS IS EXPECTED TO ENTER THE DOMINICAN REPUBLIC BY EARLY THURSDAY WHICH WILL LIKELY HELP TO SUPPRESS CONVECTIVE ACTIVITY. THE ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM THE UPPER GREAT LAKES TO THE CENTRAL GULF SUPPORTS A STATIONARY FRONT THAT ENTERS THE SW N ATLC NEAR 30N79W SW TO 29N81W...THROUGH NORTH-CENTRAL FLORIDA AND THE GULF. ISOLATED SHOWERS AND TSTMS ARE WITHIN 100 NM EITHER SIDE OF THE FRONT IN THE SW N ATLC. A MIDDLE TO UPPER LEVEL ELONGATED LOW EXTENDS FROM THE SOUTHERN BAHAMAS TO THE CENTRAL CARIBBEAN SUPPORTING A SURFACE TROUGH THAT MOVES FROM 23N67W...ACROSS HISPANIOLA TO 18N72W. SCATTERED MODERATE CONVECTION AND TSTMS EXTEND WITHIN 60 NM OFF THE NORTHERN COAST OF HAITI WHILE ISOLATED SHOWERS ARE WITHIN 50 NM EITHER SIDE OF THE TROUGH AXIS. TROPICAL STORM LORENZO IS IN THE CENTRAL ATLC. SEE THE SPECIAL FEATURES SECTION ABOVE FOR MORE INFORMATION. FURTHER EAST...SE OF LORENZO...A 1019 MB HIGH PRESSURE CENTER IS NEAR 26N40W...WHICH IS EXPECTED TO REMAIN STATIONARY WITHIN THE NEXT 24 HOURS. OVER THE EASTERN BASIN...A DISSIPATING COLD FRONT EXTENDS FROM 30N18W SW TO 28N29W WITH NO CONVECTION ASSOCIATED WITH IT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR