000 AXNT20 KNHC 202355 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU MAY 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC... ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 32W S OF 10N MOVING W AT 10-15 KT. LOW-LEVEL CYCLONIC FLOW IS NOTED AT LOW LATITUDE...S OF 6N...AS THE WAVE REMAINS EMBEDDED WITHIN THE ITCZ. WIDELY SCATTERED MODERATE CONVECTION IS FROM THE EQUATOR TO 6N BETWEEN 29W-34W. TROPICAL WAVE IS ALONG 52W S OF 11N MOVING W AT 10-15 KT. THE WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP LAYER MOISTURE AS NOTED IN TOTAL PRECIPITABLE WATER IMAGERY BETWEEN 48W-57W WITH AN AREA OF SCATTERED MODERATE CONVECTION W OF THE WAVE AXIS FROM 7N-10N BETWEEN 52W-59W. TROPICAL WAVE IS ALONG 77W S OF 12N MOVING W AT 10-15 KT. THE WAVE CONTINUES ENHANCING AFTERNOON CONVECTION OVER INLAND COLOMBIA...EASTERN PANAMA...AND ADJACENT COASTAL WATERS S OF 12N BETWEEN 73W-78W IN THE SW CARIBBEAN SEA. TROPICAL WAVE IS ALONG 84W S OF 12N MOVING W AT 10 KT. WHILE LARGELY LOCATED IN THE E PACIFIC REGION...SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS S OF 13N W OF 80W...INCLUDING INLAND PORTIONS OF WESTERN PANAMA...COSTA RICA...AND SOUTHERN NICARAGUA. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 4N32W 5N41W 5N51W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 60 NM OF THE W AFRICA COAST BETWEEN 10W-14W. ELSEWHERE...SCATTERED MODERATE CONVECTION IS WITHIN 120 NM NORTH AND 300 NM SOUTH OF THE AXIS E OF 30W. A SURFACE TROUGH IS ALONG 41W S OF 9N WITH NO SIGNIFICANT DEEP CONVECTION ASSOCIATED WITH THIS FEATURE. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY THIS EVENING INDICATES VERY DRY AND STABLE CONDITIONS ALOFT OVER MUCH OF THE GULF AND FLORIDA PENINSULA WITH NEARLY ZONAL UPPER LEVEL WESTERLY FLOW FROM ACROSS MEXICO TO 80W. THIS UPPER LEVEL REGIME IS CONTINUING TO SUPPORT A WEAK SURFACE RIDGE GENERALLY E TO SE WINDS UP TO 15 KT. HOWEVER... LOW-LEVEL MOISTURE IS ADVECTING FROM THE NW CARIBBEAN SEA AND CUBA OVER THE SE GULF WATERS AND STRAITS OF FLORIDA PROVIDING FOR ISOLATED SHOWERS S OF 25N E OF 88W. THIS ACTIVITY IS MOST FOCUSED ALONG A SURFACE TROUGH ANALYZED FROM 24N85W THROUGH THE YUCATAN CHANNEL TO A 1007 MB LOW CENTERED OFFSHORE OF THE YUCATAN PENINSULA NEAR 19N87W. GLOBAL MODEL GUIDANCE SUGGESTS THE LOW AND SURFACE TROUGH WILL DRIFT WESTWARD AROUND THE SOUTHERN PERIPHERY OF THE RIDGE AND WEAKEN AS IT MOVES OVER THE SW GULF THROUGH EARLY SUNDAY. CARIBBEAN SEA... A 1007 MB LOW IS CENTERED OFFSHORE OF THE YUCATAN PENINSULA NEAR 19N87W WITH A SURFACE TROUGH EXTENDING NE FROM THE LOW TO WESTERN CUBA AND S-SW FROM THE LOW TO THE GULF OF HONDURAS. SCATTERED SHOWERS AND TSTMS ARE OCCURRING EAST OF THE SURFACE TROUGH OVER THE NW CARIBBEAN FROM 17N-22N BETWEEN 77W-86W. THIS CONVECTIVE ACTIVITY CONTINUES TO BE ENHANCED BY UPPER LEVEL DIFFLUENCE ACROSS PORTIONS OF THE NW CARIBBEAN AND CUBA... EXTENDING NE INTO THE W ATLC E OF 80W...ALL LOCATED EAST OF AN UPPER LEVEL TROUGH AXIS ALONG 32N74W TO 20N82W. ISOLATED SHOWERS AND TSTMS SPREAD FARTHER EAST...REMAINING LARGELY N OF 17N ACROSS THE NORTHERN CARIBBEAN SEA AND GREATER ANTILLES THIS EVENING DUE TO A BROAD AREA OF CONVERGENT TRADE WINDS. WITH THE UPPER LEVEL TROUGH SLOW TO MOVE EASTWARD OVER THE NEXT COUPLE OF DAYS AND ANTICIPATED CYCLOGENESIS TO OCCUR OVER THE W ATLC ALONG 70W OVER THE NEXT 24-36 HOURS...CONTINUED PRECIPITATION IS FORECAST ACROSS PORTIONS OF HISPANIOLA AND CUBA THROUGH THE WEEKEND. ELSEWHERE...A PAIR OF TROPICAL WAVES ARE PROGRESSING WESTWARD ACROSS THE SW CARIBBEAN BRINGING SCATTERED SHOWERS AND ISOLATED TSTMS S OF 13N BETWEEN 75W-87W...INCLUDING INLAND SECTIONS OF CENTRAL AMERICA THIS EVENING. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS ACROSS THE W ATLC WITH AXIS ALONG 32N74W TO WESTERN CUBA NEAR 22N80W. THE LAST FEW VISIBLE SATELLITE IMAGES OF THE DAY INDICATE THE UPPER LEVEL TROUGH IS INDUCING CYCLOGENESIS NE OF THE BAHAMAS WITH A 1014 MB LOW CENTERED NEAR 25N75W. A SURFACE TROUGH EXTENDS ALONG 75W THROUGH THE LOW FROM 22N-28N. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER A LARGE PORTION OF THE W ATLC DUE TO THE SURFACE FEATURE AS WELL AS AN UPPER LEVEL DIFFLUENT PATTERN FROM 19N-32N BETWEEN 60W AND THE UPPER LEVEL TROUGH AXIS. THIS AREA OF LOW PRESSURE IS FORECAST TO FURTHER DEVELOP AS IT MOVES E-NE OVER THE NEXT 24-48 HOURS. A STATIONARY FRONTAL BOUNDARY IS LOCATED TO THE NW...ANALYZED FROM 32N74W TO NEAR JACKSONVILLE FLORIDA WITH ONLY ISOLATED SHOWERS OCCURRING WITHIN 30 NM OF THE FRONT. THIS FRONT IS LARGELY SUPPORTED BY THE UPPER LEVEL TROUGH AND IS FORECAST TO BECOME DIFFUSE BY LATE FRIDAY. A BROAD SURFACE RIDGE ENGULFS THE REMAINDER OF THE ATLC E OF 70W ANCHORED BY A 1031 MB HIGH CENTERED NORTH OF THE DISCUSSION AREA NEAR 37N45W. HOWEVER...TWO SURFACE TROUGHS ARE LOCATED OVER THE TROPICAL NORTH AND SW NORTH ATLC AREA. THE FIRST SURFACE TROUGH IS ANALYZED FROM 18N50W TO 13N53W WITH ISOLATED SHOWERS FROM 14N-19N BETWEEN 48W-55W. THE SECOND SURFACE TROUGH IS NORTH OF THE LEEWARD ISLANDS FROM 17N-23N ALONG 62W. ISOLATED SHOWERS ARE LOCATED WITHIN 200 NM OF THE TROUGH AXIS. A COLD FRONT ALSO SKIRTS THE NORTHERN FRINGE OF THE DISCUSSION AREA ENTERING THE EASTERN ATLC NEAR 32N31W SW TO 30N37W. ISOLATED SHOWERS ARE WITHIN 60 NM OF THE FRONT. 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