[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 221749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON SEP 22 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 12N26W TO 22N23W MOVING W AT 10-15
KT. A 1012 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 17N THAT
REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AND PART OF A SHARP
700 MB TROUGH AXIS ALOFT ALONG 26W. GIVEN THE AMPLE LOW-LEVEL
DYNAMICS IN PLACE...SCATTERED MODERATE CONVECTION IS OCCURRING
WITHIN 210 NM OF CENTER WITHIN THE NE QUADRANT.

TROPICAL WAVE EXTENDS FROM 09N44W TO 19N40W MOVING W AT 10-15
KT. THIS WAVE IS WEAKER THAN ITS EASTERN AND WESTERN
COUNTERPARTS...YET COINCIDES WITH LOW TO MIDDLE LEVEL TROUGHING
BETWEEN 38W-48W. 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 MONSOON
TROUGH REGION S OF 12N.

TROPICAL WAVE EXTENDS FROM 11N65W TO 21N62W MOVING W AT 10-15
KT. BROAD 700 MB TROUGHING IS OVER THE EASTERN CARIBBEAN SEA AND
VICINITY BETWEEN 58W-68W. LOW-LEVEL MOISTURE CONVERGENCE REMAINS
MAXIMIZED TO THE EAST OF THE WAVE AXIS SUPPORTING WIDELY
SCATTERED MODERATE CONVECTION FROM 10N-21N BETWEEN 56W-63W.
PRECIPITATION PROBABILITIES ARE EXPECTED TO INCREASE ACROSS THE
LESSER ANTILLES THROUGH EARLY TUESDAY AS THIS AREA OF WEATHER
PASSES WEST BY WEDNESDAY.

TROPICAL WAVE EXTENDS FROM 11N78W TO 20N81W MOVING W AT 10-15
KT. THE HAS BEEN RE-POSITIONED SLIGHTLY EAST THIS MORNING BASED
ON LONG-TERM SATELLITE IMAGERY TRENDS AND THE PRESENCE OF BROAD
MID-LEVEL TROUGHING ACROSS THE WESTERN CARIBBEAN SEA. WIDELY
SCATTERED MODERATE CONVECTION IS OCCURRING FROM 13N-17N BETWEEN
73W-82W.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 07N12W TO
05N19W. THE MONSOON TROUGH RESUMES NEAR 15N19W TO A 1012 MB LOW
NEAR 17N25W TO 12N30W TO 08N47W. THE INTERTROPICAL CONVERGENCE
ZONE AXIS EXTENDS FROM 08N47W TO 06N55W. ASIDE FROM CONVECTION
OCCURRING WITH THE TROPICAL WAVES...SCATTERED MODERATE
CONVECTION IS FROM 03N-07N BETWEEN 15W-21W...FROM 11N-16N
BETWEEN 14W-20W. ISOLATED MODERATE CONVECTION IS FROM 11N-15N
BETWEEN 25W-30W...AND FROM 09N-14N BETWEEN 33W-42W.

...DISCUSSION...

GULF OF MEXICO...
MIDDLE TO UPPER LEVEL TROUGHING IS NOTED ON WATER VAPOR IMAGERY
OVER THE EASTERN CONUS THIS AFTERNOON WITH THE BASE OF THE
TROUGH DIPPING OVER THE EASTERN GULF NEAR 27N86W. AMPLE DYNAMICS
ALOFT ARE RESULTING IN A 1013 MB LOW CENTERED NEAR 27N88W THAT
IS ANALYZED ALONG A STATIONARY FRONT EXTENDING FROM THE SW NORTH
ATLC ACROSS THE NORTHERN FLORIDA PENINSULA AND INTO THE GULF
WATERS NEAR 29N83W. THE FRONT EXTENDS INTO THE LOW THEN W-SW TO
THE TEXAS GULF COAST NEAR BROWNSVILLE. MOST CONVECTION IN THE
FORM OF SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS THE
EASTERN GULF FROM 24N-29N BETWEEN 82W-90W. SOME OF THIS ACTIVITY
STRETCHES ACROSS THE SOUTHERN FLORIDA PENINSULA AND FLORIDA
STRAITS BETWEEN 79W-82W. A PRE-FRONTAL SURFACE TROUGH ALSO
EXTENDS FROM THE LOW SW TO 24N92W TO 20N95W PROVIDING FOCUS FOR
ISOLATED SHOWERS AND TSTMS WITHIN 90 NM EITHER SIDE OF THE
BOUNDARY. OTHERWISE...TO THE NORTH OF THE FRONT...HIGH PRESSURE
IS HELD AT BAY ACROSS THE NW GULF COAST AND SOUTHERN PLAINS AS A
WEAK COLD FRONT SLIDES ACROSS THE SE CONUS EAST OF THE
MISSISSIPPI RIVER AND WILL MERGE WITH THE STATIONARY FRONT ON
TUESDAY.

CARIBBEAN SEA...
TWO TROPICAL WAVE ARE IMPACTING THE CARIBBEAN THIS AFTERNOON...
ONE ALONG 64W AND THE OTHER ALONG 80W. THE EASTERN-MOST TROPICAL
WAVE IS BRINGING INCREASED COVERAGE OF SHOWERS AND TSTMS THIS
AFTERNOON TO THE LESSER ANTILLES. THE AREA OF CONVECTION IS
EXPECTED TO FOLLOW ON THE EASTERN PERIPHERY OF TROPICAL WAVE AS
IT MOVES WEST AND BEGIN IMPACTING PUERTO RICO AND HISPANIOLA ON
TUESDAY INTO WEDNESDAY. THE WESTERN-MOST TROPICAL WAVE IS
LARGELY PROVIDING SCATTERED SHOWERS AND TSTMS TO THE OPEN WATERS
OF THE WESTERN CARIBBEAN FROM 13N-20N BETWEEN 69W-82W...AND THIS
CONVECTION CONTINUES TO BE ENHANCED BY AN UPPER LEVEL LOW
CENTERED OVER THE NW CARIBBEAN NEAR 17N82W. OTHERWISE...THE
MONSOON TROUGH AXIS EXTENDS ALONG 10N/11N BETWEEN NORTHERN
COLOMBIA AND COSTA RICA WITH ISOLATED SHOWERS AND TSTMS
OCCURRING S OF 12N.

...HISPANIOLA...
CURRENTLY...FAIR SKIES AND CONDITIONS PREVAIL ACROSS THE ISLAND
THIS AFTERNOON. FAIR SKIES ALSO PREVAIL TO THE EAST ACROSS
PUERTO RICO WITH AN APPROACHING TROPICAL WAVE EAST OF THE US/UK
VIRGIN ISLANDS. THE FAVORABLE WEATHER IS EXPECTED TO LAST UNTIL
TUESDAY WHEN THE TROPICAL WAVE WILL PASS BY AND BRING INCREASED
PROBABILITY OF SCATTERED SHOWERS AND TSTMS ON THE EASTERN
PERIPHERY OF THE WAVE AXIS.

ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH IS OVER THE EASTERN CONUS THAT
SUPPORTS A STATIONARY FRONT ANALYZED FROM 32N70W SW TO 30N75W TO
THE FLORIDA PENINSULA NEAR 29N81W. WIDELY SCATTERED SHOWERS AND
TSTMS ARE OCCURRING N OF 23N W OF 74W ACROSS A PORTION OF THE SW
NORTH ATLC...INCLUDING THE FLORIDA PENINSULA AND WEST INTO THE
EASTERN GULF OF MEXICO. THE FRONT IS EXPECTED TO MERGE WITH A
COLD FRONT CURRENTLY TO THE NORTH DRAPED ACROSS THE CAROLINAS
AND COASTAL GULF PLAIN ON TUESDAY. FARTHER EAST...AN UPPER LEVEL
LOW IS CENTERED NEAR 24N54W THAT SUPPORTS A BROAD AREA OF
CLOUDINESS WITH EMBEDDED AREAS OF ISOLATED SHOWERS AND TSTMS
OCCURRING FROM 21N-32N BETWEEN 44W-57W. THE TAIL END OF A
FRONTAL BOUNDARY ANALYZED AS A STATIONARY FRONT FROM 29N44W TO
30N53W EXTENDS INTO THIS AREA OF CONVECTION PROVIDING ENHANCED
FOCUS ON CONVECTION OCCURRING NEAR THE FRONT. TO THE EAST...A
COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N31W NEAR A 1017 MB
LOW CENTERED ALONG THE FRONT AT 31N. THE FRONT EXTENDS SW TO
28N36W THEN W-NW TO THE STATIONARY FRONT NEAR 29N44W. ISOLATED
SHOWERS ARE POSSIBLE WITHIN 60 NM EITHER SIDE OF THE COLD FRONT.

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

$$
HUFFMAN


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