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Atlantic Tropical Weather Discussion



000
AXNT20 KNHC 231745
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE SEP 23 2014

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

...TROPICAL WAVES...                                     
TROPICAL WAVE EXTENDS FROM 13N29W TO 23N27W MOVING W-NW AT 10 
KT. A 1014 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 18N THAT 
HAS BEGIN TO SLOWLY PULL NORTHWEST OF THE INFLUENCE OF THE 
MONSOON TROUGH ZONE. SHARP 700 MB TROUGHING EVIDENT YESTERDAY 
HAS SINCE BECOME BROAD AND STRETCHED BETWEEN 25W-40W. ISOLATED 
MODERATE CONVECTION IS FROM 18N-20N BETWEEN 24W-29W.

TROPICAL WAVE EXTENDS FROM 10N48W TO 19N46W MOVING W AT 10-15 
KT. THE WAVE REMAINS RELATIVELY WEAK AND COINCIDES WITH LOW TO 
MIDDLE LEVEL TROUGHING BETWEEN 45W-53W. ONE REASON THE WAVE 
REMAINS WEAKER IS THE PRESENCE OF A DRY AND STABLE SAHARAN AIR 
LAYER KEEPING CONVECTION TO A MINIMUM AND LARGELY CONFINED TO 
THE ITCZ REGION ON THE EASTERN PERIPHERY OF THE WAVE AXIS.

TROPICAL WAVE EXTENDS FROM 13N71W TO 23N69W MOVING W AT 15 KT. 
SUBTLE 700 MB TROUGHING IS NOTED OVER THE CENTRAL CARIBBEAN SEA 
AND VICINITY BETWEEN 66W-73W WITH LOW-LEVEL MOISTURE CONVERGENCE 
MAXIMIZED GENERALLY TO THE EAST OF THE WAVE AXIS.  WIDELY 
SCATTERED MODERATE CONVECTION IS FROM 18N-24N BETWEEN 63W-71W. 
ISOLATED MODERATE CONVECTION IS ELSEWHERE FROM 12N-24N BETWEEN 
60W-71W. THE BULK OF THE CONVECTIVE PRECIPITATION REMAINS NORTH 
OF THE MONA PASSAGE AND PUERTO RICO...AND WILL BRING INCREASED 
PRECIPITATION PROBABILITIES TO HISPANIOLA DURING THE NEXT 24 
HOURS.

TROPICAL WAVE EXTENDS FROM 09N86W TO 22N84W MOVING W AT 10-15 
KT. THE WAVE CONTINUES TO MOVE BENEATH AN UPPER LEVEL DIFFLUENT 
ZONE OVER THE NW CARIBBEAN SEA EAST OF AN UPPER LEVEL TROUGH 
AXIS ALONG 88W. LOW-LEVEL MOISTURE CONVERGENCE ASSOCIATED WITH 
THE WAVE AND THE AID OF UPPER LEVEL DYNAMICS ARE GENERATING 
WIDELY SCATTERED MODERATE CONVECTION FROM 17N-22N BETWEEN 78W-
83W...AND FROM 15N-22N BETWEEN 84W-89W.

...ITCZ/MONSOON TROUGH...                                     
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 13N17W TO 
A 1014 MB LOW CENTERED NEAR 07N21W. THE MONSOON TROUGH AXIS 
RESUMES NEAR 14N30W TO 11N35W TO 11N37W. THE INTERTROPICAL 
CONVERGENCE ZONE AXIS EXTENDS FROM 11N37W TO 12N41W TO 08N51W TO 
09N55W. ASIDE FROM CONVECTION OCCURRING WITH THE TROPICAL 
WAVES...SCATTERED MODERATE CONVECTION IS FROM 03N-14N BETWEEN 
18W-26W...AND FROM 10N-15N BETWEEN 40W-46W.

...DISCUSSION... 

GULF OF MEXICO...                                               
A MIDDLE TO UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY OVER 
THE SE CONUS THIS AFTERNOON CENTERED NEAR 33N82W WITH THE 
ASSOCIATED TROUGH AXIS EXTENDING S-SW TO A BASE OVER THE SOUTH-
CENTRAL GULF NEAR 23N88W. THE UPPER LEVEL LOW SUPPORTS A COLD 
FRONT ANALYZED FROM JACKSONVILLE FLORIDA SW TO THE MISSISSIPPI 
RIVER DELTA REGION NEAR 28N90W. TO THE IMMEDIATE SOUTH OF THE 
COLD FRONT A LINGERING STATIONARY FRONT EXTENDS FROM 30N81W SW 
INTO A WEAK 1014 MB LOW CENTERED NEAR 28N84W TO 24N91W THAT 
BECOMES A SURFACE TROUGH TO 22N96W. LOW-LEVEL MOISTURE CONTINUES 
TO POOL ALONG THE STATIONARY FRONT WITH ISOLATED SHOWERS AND 
TSTMS OCCURRING WITHIN 75 NM EITHER SIDE OF THE BOUNDARY E OF 
91W. ISOLATED SHOWERS AND TSTMS ARE ALSO OCCURRING NEAR THE 
WESTERN EXTENT OF THE SURFACE TROUGH FROM 21N-24N W OF 94W. THE 
FRONTS ARE EXPECTED TO MERGE DURING THE NEXT 6 HOURS ACROSS THE 
NE GULF WITH CONTINUED MOISTURE ADVECTION AND CONVECTION 
OCCURRING ACROSS THE SE GULF WATERS AND FLORIDA PENINSULA 
THROUGH THE OVERNIGHT HOURS INTO WEDNESDAY. OTHERWISE...TO THE 
NORTH AND WEST OF THE COLD FRONT ACROSS THE GULF COAST AND NW 
GULF WATERS...HIGH PRESSURE REMAINS IN CONTROL PROVIDING MOSTLY 
CLEAR SKIES AND FAIR CONDITIONS W OF MOBILE BAY TO CORPUS 
CHRISTI TEXAS.

CARIBBEAN SEA...                                              
TWO TROPICAL WAVE ARE IMPACTING THE CARIBBEAN THIS AFTERNOON... 
ONE ALONG 70W AND THE OTHER ALONG 85W. THE EASTERN-MOST TROPICAL 
WAVE IS BRINGING WIDELY SCATTERED SHOWERS AND TSTMS TO MUCH OF 
THE EASTERN CARIBBEAN E OF 70W...WITH THE MOST INTENSE 
CONVECTION OCCURRING ACROSS THE WINDWARD ISLANDS AND AREAS TO 
THE NORTH OF THE MONA PASSAGE AND HISPANIOLA. CONVECTION IS 
EXPECTED TO FOLLOW PRIMARILY ON THE EASTERN PERIPHERY OF 
TROPICAL WAVE AS IT MOVES WEST AND BEGINS IMPACTING HISPANIOLA 
THROUGH THE OVERNIGHT HOURS AND WINDWARD PASSAGE BY EARLY 
WEDNESDAY. THE WESTERN-MOST TROPICAL WAVE IS PROVIDING SCATTERED 
SHOWERS AND TSTMS ACROSS THE OPEN WATERS OF THE CENTRAL AND 
WESTERN CARIBBEAN FROM 10N-22N BETWEEN 73W-84W...AND THIS 
CONVECTION CONTINUES TO BE ENHANCED BY UPPER LEVEL DIFFLUENCE 
MAXIMIZED OVER THE NW CARIBBEAN.

...HISPANIOLA...                                             
CURRENTLY...A TROPICAL WAVE LIES ALONG 70W BRINGING SCATTERED 
SHOWERS AND ISOLATED TSTMS TO THE EASTERN THIRD OF THE ISLAND AT 
THIS TIME. MOST OF THE CONVECTIVE PRECIPITATION ASSOCIATED WITH 
THE WAVE IS NOTED ACROSS THE NORTHEASTERN COASTAL WATERS AND 
MONA PASSAGE THIS AFTERNOON...HOWEVER THIS AREA IS EXPECTED TO 
MOVE WEST PROVIDING THE ENTIRE ISLAND WITH SHOWERS AND TSTMS 
THROUGH THE EVENING AND OVERNIGHT HOURS INTO WEDNESDAY.

ATLANTIC OCEAN...                                               
A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE CAROLINAS NEAR 
34N82W WITH TROUGHING THAT EXTENDS S-SW OVER THE EASTERN GULF OF 
MEXICO THIS AFTERNOON. THE LOW AND TROUGHING SUPPORT A MERGING 
STATIONARY FRONT EXTENDING FROM 32N80W TO NEAR JACKSONVILLE 
FLORIDA AND INTO THE NE GULF WATERS. A PRE-FRONTAL SURFACE 
TROUGH EXTENDS FROM 32N72W SW TO 30N76W TO 28N78W. PLENTY OF LOW-
LEVEL MOISTURE CONVERGENCE SOUTH OF THE STATIONARY FRONT AND 
ALONG THE SURFACE TROUGH AXIS IS GENERATING AREAS OF SCATTERED 
SHOWERS AND TSTMS FROM 23N-27N BETWEEN 76W-82W...INCLUDING THE 
FLORIDA STRAITS...SOUTHERN FLORIDA PENINSULA...AND PORTIONS OF 
THE NW BAHAMAS...AND AN AREA N OF 28N BETWEEN 71W-81W. TO THE 
SOUTHWEST...A TROPICAL WAVE EXTENDS ALONG 70W WITH AN AREA OF 
SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING NORTH OF PUERTO 
RICO...THE MONA PASSAGE...AND HISPANIOLA. ENERGY ASSOCIATED WITH 
THE NORTHERN EXTENT OF THE WAVE IS FORECAST TO MOVE W-NW AND 
IMPACT THE BAHAMAS...CUBA...AND FLORIDA PENINSULA BY LATE 
THURSDAY. FARTHER EAST...A BROAD ELONGATED UPPER LEVEL LOW IS 
CENTERED NEAR 26N55W THAT SUPPORTS A BROAD AREA OF CLOUDINESS 
WITH EMBEDDED ISOLATED SHOWERS AND TSTMS OCCURRING FROM 24N-31N 
BETWEEN 48W-56W. OTHERWISE...SURFACE RIDGING INFLUENCES THE 
REMAINDER OF THE CENTRAL AND EASTERN ATLC N OF 23N WITH THE 
EXCEPTION OF A WEAK 1018 MB LOW CENTERED NEAR 29N31W AND A 
SURFACE TROUGH EXTENDING W-SW FROM THE LOW TO 29N37W TO 26N45W. 
ISOLATED SHOWERS ARE POSSIBLE WITHIN 120 NM EITHER SIDE OF THE 
BOUNDARY. AN EARLIER MORNING ASCAT PASS AROUND 23/1140 UTC ALSO 
INDICATED STRONG NORTHEAST WINDS IN THE RANGE OF 20 TO 30 KT N 
OF 30N BETWEEN 28W-43W.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
WWW.HURRICANES.GOV/MARINE

$$ 
HUFFMAN



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Page last modified: Tuesday, 23-Sep-2014 17:45:20 UTC