[Tropical] Tropical Weather Discussion

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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
HTTP://WWW.HURRICANES.GOV/MARINE

$$
HUFFMAN


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