000 AXNT20 KNHC 121155 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT MON JUL 12 2010 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC... ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 18N23W TO 8N22W MOVING W 15-20 KT. WAVE IS POSITIONED FARTHER WWD THAN EXPECTED DUE TO SURFACE WIND OBSERVATIONS FROM SAL CAPE VERDE ISLANDS INDICATING THAT THE WAVE HAD JUST PASSED. THE WAVE LIES AHEAD OF A MAXIMUM IN DEEP LAYER MOISTURE. BROAD CYCLONIC FLOW IS ALSO SEEN IN THE FIRST VISIBLE SATELLITE IMAGES OF THE DAY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-11N BETWEEN 16W-21W...FROM 12N-14N BETWEEN 19W-22W...AND FROM 9N-11N BETWEEN 21W-25W. TROPICAL WAVE EXTENDS FROM 18N42W TO 4N44W MOVING W NEAR 20 KT. WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. DUE TO A DRY SAHARAN AIR LAYER AND ASSOCIATED DUST...CONVECTION IS LIMITED NEAR THE WAVE. ISOLATED MODERATE/STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE AXIS S OF 10N. TROPICAL WAVE EXTENDS FROM 20N79W TO 7N81W MOVING W NEAR 20 KT. WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE THAT COVERS MUCH OF THE WRN CARIBBEAN INDICATED BY TOTAL PRECIPITABLE WATER IMAGERY. THE WAVE ALSO LIES AHEAD OF A DRY SAHARAN AIR LAYER AND A LARGE AREA OF DUST ACROSS THE TROPICAL ATLC AND INTO THE ERN CARIBBEAN. HOWEVER...DUE TO A DIFFLUENT ZONE ALOFT NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS ACROSS THE SW CARIBBEAN FROM 9N-14N BETWEEN 74W-83W. TROPICAL WAVE EXTENDS FROM 18N87W ACROSS HONDURAS INTO THE E PACIFIC TO NEAR 7N88W MOVING W 15-20 KT. WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE THAT COVERS MUCH OF THE WESTERN CARIBBEAN EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 15N-18N BETWEEN 83W-88W. MORE CONVECTION IS IN THE EPAC. SEE TWDEP FOR MORE DETAILS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 12N13W 8N30W 10N45W 8N54W 9N61W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 3N-6N BETWEEN 26W-38W...FROM 9N-11N BETWEEN 35W-39W...FROM 2N-6N BETWEEN 49W-52W...FROM 8N-10N BETWEEN 51W-54W...AND INLAND OVER NE SOUTH AMERICA FROM 2N-9N BETWEEN 55W-62W. ...DISCUSSION... GULF OF MEXICO... A DRY AND STABLE AIRMASS LIES ACROSS MUCH OF THE GULF OF MEXICO AROUND AN UPPER LEVEL RIDGE CENTERED OVER TEXAS NEAR 30N98W MAINTAINING FAIR CONDITIONS ACROSS MUCH OF THE BASIN. A FEW SHOWERS/THUNDERSTORMS ARE IN THE FAR SW GULF AROUND AN UPPER LEVEL TROUGH EXTENDING FROM CUBA TO THE NRN YUCATAN PENINSULA. AN UPPER LEVEL RIDGE IS TO THE S OF THE UPPER TROUGH COVERING THE NW CARIBBEAN...SRN YUCATAN PENINSULA AND CENTRAL MEXICO. AT THE SURFACE...RIDGING DOMINATES ANCHORED BY A 1016 MB CENTER W OF S FLORIDA NEAR 26N84W. LIGHT ANTI-CYCLONIC FLOW IS AROUND THE SURFACE RIDGE WITH STRONGER SLY WINDS REACHING UP TO 20 KT ALONG THE TEXAS COASTLINE. EXPECT SURFACE RIDGING TO REMAIN ACROSS THE BASIN ALONG WITH DRY AND AND MOSTLY FAIR WEATHER. CARIBBEAN SEA... A PAIR OF TROPICAL WAVES ARE ACROSS THE WRN CARIBBEAN BRINGING ENHANCED MOISTURE TO THIS HALF OF THE AREA AND SUPPORTING SHOWERS/THUNDERSTORMS ACROSS MUCH OF THE SW CARIBBEAN AND N OF HONDURAS. SEE TROPICAL WAVE SECTION ABOVE FOR MORE DETAILS. SOME OF THIS ACTIVITY IS ENHANCED BY DIFFLUENCE ALOFT BETWEEN AN UPPER LEVEL RIDGE COVERING THE NW CARIBBEAN AND YUCATAN PENINSULA AND AN UPPER LEVEL TROUGH COVERING THE ERN CARIBBEAN EXTENDING FROM THE LEEWARD ISLANDS TO NEAR 13N79W. THIS UPPER LEVEL TROUGH IS ACCOMPANIED BY DRY AIR EXTENDING FROM THE TROPICAL ATLC. SEVERAL STATIONS ARE ALSO INDICATING THE PRESENCE OF DUST. DUE TO THIS STABLE AIR MASS...MUCH OF THE ERN CARIBBEAN IS EXPERIENCING GENERALLY FAIR WEATHER. HOWEVER...A FEW ISOLATED SHOWERS ARE NOTED FROM 12N-16N BETWEEN 62W-69W EMBEDDED IN THE ELY TRADE WIND FLOW. EXPECT SHOWERS/THUNDERSTORMS TO CONTINUE ACROSS THE WRN CARIBBEAN DUE TO THE TROPICAL WAVES WHILE DRY AIR MAINTAINS FAIR WEATHER ACROSS THE ERN CARIBBEAN. ATLANTIC OCEAN... A SHORTWAVE UPPER LEVEL TROUGH JUST OFF THE ERN UNITED STATES SEABOARD HAS DIPPED INTO THE NRN PORTION OF THE DISCUSSION AREA SUPPORTING ISOLATED SHOWERS/THUNDERSTORMS FROM 27N-31N BETWEEN 74W-77W. A SECOND SHORTWAVE UPPER LEVEL TROUGH EXTENDS OVER THE SE BAHAMAS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS FROM 21N-25N BETWEEN 71W-75W...AND ISOLATED SHOWERS/THUNDERSTORMS FROM 22N-26N BETWEEN 66W-70W. A NARROW UPPER LEVEL RIDGE IS WEDGED BETWEEN THESE TWO UPPER SHORTWAVES. AT THE SURFACE...SURFACE RIDGING DOMINATES THE ENTIRE BASIN ANCHORED BY A 1030 MB HIGH CENTERED NEAR 39N47W. A DRY SAHARAN AIR LAYER ACCOMPANIED BY DUST COVERS MUCH OF THE ERN AND CENTRAL ATLC KEEPING CONDITIONS FAIR. ALOFT...AN UPPER LEVEL TROUGH IS BETWEEN 52W-65W...WITH UPPER RIDGING BETWEEN 45W-52W...FOLLOWED BY ANOTHER UPPER LEVEL TROUGH BETWEEN 32W-45W. AN UPPER LEVEL RIDGE COVERS THE FAR ERN ATLC CENTERED JUST W OF THE CANARY ISLANDS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON