...TROPICAL WEATHER DISCUSSION COURTESY NATIONAL HURRICANE CENTER... ...SPECIAL FEATURES... A TROPICAL WAVE LOCATED A COUPLE OF HUNDRED MILES SOUTHEAST OF THE CAPE VERDE ISLANDS IS ASSOCIATED WITH A 1008 MB LOW PRESSURE EMBEDDED WITHIN THE MONSOON TROUGH AXIS. ITS AXIS EXTENDS FROM 19N22W TO THE LOW NEAR 13N22W. THE SYSTEM REMAINS WELL ORGANIZED AND A TROPICAL DEPRESSION COULD FORM LATER TODAY OR ON THURSDAY. A CLUSTER OF MODERATE CONVECTION IS FROM 11N-15N BETWEEN 22W- 25W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 07N-15N BETWEEN 16W-33W. CURRENTLY...THIS SYSTEM HAS A HIGH CHANCE...80 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THIS SYSTEM WILL LIKELY BRING SHOWERS AND GUSTY WINDS TO THE SOUTHERN CAPE VERDE ISLANDS LATER TODAY AND THURSDAY AS IT MOVES WESTWARD AT 10 TO 15 MPH. A TROPICAL WAVE IS OVER THE NORTHWESTERN CARIBBEAN SEA ASSOCIATED WITH A 1009 MB LOW PRESSURE. ITS AXIS EXTENDS FROM 22N85W TO THE LOW NEAR 17N84W TO 14N84W. THE SYSTEM IS MOVING TOWARD THE WEST-NORTHWEST NEAR 15 KT. CLOUDINESS AND SHOWERS ASSOCIATED WITH THIS LOW CONTINUE TO SHOW SIGNS OF ORGANIZATION...AND A TROPICAL DEPRESSION COULD FORM BEFORE THE DISTURBANCE REACHES THE YUCATAN PENINSULA ON THURSDAY. SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS ARE FROM 14N-24N BETWEEN 79W-90W WITH THE STRONGEST CONVECTION BEING E OF THE LOW AND S OF WESTERN CUBA. AFTER THURSDAY...THIS WEATHER SYSTEM IS FORECAST TO MOVE OVER THE GULF OF MEXICO...WHERE UPPER-LEVEL WINDS WILL LIKELY BE A LITTLE LESS FAVORABLE FOR DEVELOPMENT. THIS SYSTEM HAS A HIGH CHANCE...70 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. HEAVY RAINS AND GUSTY WINDS ARE FORECAST TO SPREAD OVER THE YUCATAN PENINSULA AND BELIZE DURING THE NEXT DAY OR TWO. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE CENTRAL TROPICAL ATLANTIC EXTENDING AN AXIS FROM 19N42W TO 12N43W AND MOVING W NEAR 15 KT. TOTAL PRECIPITABLE WATER IMAGERY SHOW THE WAVE IS EMBEDDED WITHIN A MODERATE MOIST ENVIRONMENT AT THE LOWER LEVELS. HOWEVER...METEOSAT SATELLITE IMAGERY SHOW SAHARAN DUST AND DRY AIR SPREADING OVER THE WAVE ENVIRONMENT WHICH IS SUPPRESSING CONVECTION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST NEAR 21N17W TO 20N19W. IT RESUMES FROM THE 1008 MB LOW NEAR 13N22W TO 12N32W 13N42W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS ALONG 13N42W TO 08N52W 10N65W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES ALREADY DISCUSSED...SCATTERED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 33W-43W. SIMILAR CONVECTION IS WITHIN 140 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 48W-52W. ...DISCUSSION... GULF OF MEXICO... SURFACE TROUGHINESS STARTS TO BUILD ACROSS THE SOUTHERN GULF AS THE TROPICAL WAVE OVER THE NORTHWESTERN CARIBBEAN SEA CONTINUE A W-NW TRACK TOWARDS THE YUCATAN PENINSULA. ANTICYCLONIC WIND FLOW IN THE RANGE OF 5-10 KT IS OVER THE NW GULF N OF 25N W OF 92W ANCHORED BY A 1015 MB HIGH CENTER NEAR 27N94W. A PREFRONTAL SURFACE TROUGH IS OVER THE NORTHERN CENTRAL AND NE GULF EXTENDING FROM THE FLORIDA PANHANDLE NEAR 30N86W TO 28N90W 29N94W. A COL OR AREA OF LOW PRESSURE CONTINUES IN THE MIDDLE LEVELS BETWEEN THE FLORIDA PANHANDLE AND LOUISIANA. THIS SCENARIO ALONG WITH THE SURFACE PRE-FRONTAL TROUGH IS SUPPORTING SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS INLAND WHICH EXTENDS WITHIN 100 NM OFF THE COASTLINES BETWEEN 87W-94W. ISOLATED SHOWERS ASSOCIATED WITH THE APPROACHING TROPICAL SYSTEM ARE OCCURRING IN THE SE GULF...INCLUDING THE STRAITS OF FLORIDA AND THE YUCATAN CHANNEL. OTHERWISE...FAIR WEATHER IS OVER THE REMAINDER BASIN SUPPORTED BY A TONGUE OF DRY AIR IN THE LOWER AND MIDDLE LEVELS. THE TROPICAL SYSTEM IN THE NW CARIBBEAN COULD BECOME A TROPICAL DEPRESSION BEFORE IT REACHES THE YUCATAN PENINSULA ON THURSDAY. AFTER THURSDAY...THIS WEATHER SYSTEM IS FORECAST TO MOVE OVER THE GULF OF MEXICO...WHERE UPPER-LEVEL WINDS WILL LIKELY BE A LITTLE LESS FAVORABLE FOR DEVELOPMENT. HEAVY RAINS AND GUSTY WINDS ARE FORECAST TO SPREAD OVER THE YUCATAN PENINSULA DURING THE NEXT DAY OR TWO. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 19N81W PROVIDING A BROAD AREA OF MIDDLE TO UPPER DIFFLUENCE OVER THE NW BASIN. A TROPICAL WAVE AND ASSOCIATED LOW PRESSURE AREA ARE COUPLED TO THIS UPPER LEVEL FEATURE AS WELL AS MAXIMUM MOISTURE DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY. THESE UPPER LEVEL AND SURFACE CONDITIONS ARE SUPPORTING SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS FROM 14N-24N BETWEEN 79W-90W WITH THE STRONGEST CONVECTION BEING E OF THE LOW AND S OF WESTERN CUBA. NORTHEASTERLY FLOW FROM AN UPPER LEVEL LOW CENTERED IN THE ATLC NEAR 28N62W IS ADVECTING MOISTURE TO HISPANIOLA THAT ALONG WITH MIDDLE LEVEL DIFFLUENCE SUPPORT SCATTERED RAINSHOWERS AND TSTMS OVER HAITI AND WESTERN DOMINICAN REPUBLIC. OTHERWISE...A DRY AIRMASS SPREADS OVER THE EASTERN CARIBBEAN WHICH IS SUPPORTING FAIR WEATHER CONDITIONS. THE TROPICAL DISTURBANCE OVER THE NW BASIN COULD BECOME A TROPICAL DEPRESSION BEFORE IT REACHES THE YUCATAN PENINSULA ON THURSDAY. HISPANIOLA... NORTHEASTERLY FLOW FROM AN UPPER LEVEL LOW CENTERED IN THE ATLC NEAR 28N62W IS ADVECTING MOISTURE TO HISPANIOLA THAT ALONG WITH MIDDLE LEVEL DIFFLUENCE SUPPORT SCATTERED RAINSHOWERS AND TSTMS OVER HAITI AND WESTERN DOMINICAN REPUBLIC. AN AIRMASS CURRENTLY SPREADING OVER THE EASTERN CARIBBEAN WILL CONTINUE A WESTWARD TRACK WHICH WILL LIMIT CONVECTIVE ACTIVITY THROUGH THE WEEKEND. ATLANTIC OCEAN... SCATTERED SHOWERS OVER THE NORTHERN FLORIDA PENINSULA EXTEND WITHIN 70 NM OF THE COASTLINE FROM 28N-30N. SIMILAR CONVECTION THIS TIME ASSOCIATED WITH THE TROPICAL DISTURBANCE OVER THE NW CARIBBEAN SEA IS IN THE BAHAMAS S OF 26N W OF 76W. FARTHER EAST IN THE SW N ATLC...AN UPPER LEVEL LOW IS CENTERED NEAR 28N62W AND SUPPORTS A BROAD AREA OF WIDELY SCATTERED SHOWERS AND TSTMS FROM 20N-29N BETWEEN 61W-70W. OTHERWISE...ASIDE FROM THE TROPICAL WAVES ALREADY DISCUSSED ABOVE...A SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED NEAR 34N44W DOMINATES THE OVERALL PATTERN. FURTHERMORE...DRY AIR IN THE LOWER AND MIDDLE LEVELS SUPPORTS FAIR WEATHER IN THE REMAINDER BASIN.
Posted on: Thu, 15 Aug 2013 02:18:58 +0000
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