[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 212346
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON OCT 21 2013

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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...
TROPICAL STORM LORENZO IS CENTERED NEAR 28.9N 54.9W AT 21/2100
UTC OR ABOUT 550 NM ESE OF BERMUDA MOVING NNE AT 6 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM SUSTAINED WIND
SPEED IS 35 KT WITH GUSTS TO 45 KT. SCATTERED MODERATE
CONVECTION IS FROM 27N-31N BETWEEN 51W-54W. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 07N40W TO 15N43W MOVING W AT 15 KT.
THE WAVE REMAINS EMBEDDED WITHIN THE ITCZ AND ALSO WITHIN VERY
BROAD AND WEAK SURFACE TO 700 MB TROUGHING BETWEEN 40W-45W. MOST
ENERGY FROM THE WAVE HAS BECOME MORE DIFFUSE OVER THE LAST 24
HOURS DUE TO UPPER LEVEL WESTERLIES TO THE NORTH ON THE SOUTHERN
PERIPHERY OF AN UPPER LEVEL LOW CENTERED NEAR 21N40W. VERY DRY
AIR ALOFT IS NOTED N OF 12N IN THE VICINITY OF THE WAVE THUS ANY
SIGNIFICANT DEEP CONVECTION WITH THE WAVE IS LIMITED AT THIS
TIME. ISOLATED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 38W-
44W.

TROPICAL WAVE EXTENDS FROM 10N73W TO 17N71W MOVING W AT 15 KT.
THE WAVE CONTINUES TO BE SOMEWHAT DIFFICULT TO TRACK HOWEVER
GLOBAL MODEL DATA INDICATES BROAD LOW-LEVEL TROUGHING ACROSS THE
CENTRAL CARIBBEAN SEA THIS EVENING. NO SIGNIFICANT DEEP
CONVECTION IS NOTED IN THE VICINITY OF THE WAVE AXIS AT THIS
TIME.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO
09N23W TO 06N29W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 06N29W TO 05N31W TO 07N40W TO 09N53W. ASIDE FROM
THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE ALONG 42W...
WIDELY SCATTERED MODERATE CONVECTION IS FROM 01N-07N BETWEEN 19W-
31W...AND FROM 09N-12N BETWEEN 48W-55W.

...DISCUSSION...

GULF OF MEXICO...
MIDDLE TO UPPER LEVEL SOUTHWESTERLY FLOW ALOFT IS NOTED ON WATER
VAPOR IMAGERY THIS EVENING OVER THE GULF BETWEEN LONGWAVE
TROUGHING OVER THE CENTRAL CONUS AND AN UPPER LEVEL ANTICYCLONE
CENTERED OVER THE BAHAMAS NEAR 25N75W. WHILE STRONGER UPPER
LEVEL DYNAMICS ASSOCIATED WITH THE TROUGH REMAIN OVER THE TEXAS
AND OKLAHOMA PANHANDLES AS WELL AS NEW MEXICO...A STATIONARY
FRONT IS ANALYZED FROM THE FLORIDA PENINSULA NEAR 29N82W W-SW TO
27N88W WHERE THE FRONT BECOMES WARM TO NEAR BROWNSVILLE TEXAS
NEAR 26N97W. THE STATIONARY FRONT IS FAIRLY PRECIPITATION-FREE
THIS EVENING...HOWEVER AS THE WARM FRONT SLOWLY CONTINUES TO
LIFT NORTHWARD MULTI-LAYERED CLOUDINESS INCREASES ACROSS THE
WESTERN GULF W OF 88W WITH SCATTERED SHOWERS AND ISOLATED TSTMS
OCCURRING N OF 21N WEST OF A LINE FROM 21N92W TO THE FLORIDA
PANHANDLE NEAR 30N85W. THE STRONGEST CONVECTION IS CLOSELY
ASSOCIATED WITH THE WARM FRONTAL BOUNDARY IN THE VICINITY OF
26N94W. THROUGH THE OVERNIGHT HOURS INTO INTO EARLY TUESDAY THE
NEXT COLD FRONT IS FORECAST TO EMERGE OFF THE TEXAS AND
LOUISIANA GULF COAST SHIFTING WINDS NORTHERLY THEN NORTHEASTERLY
INTO WEDNESDAY AS THE COLD FRONT CONTINUES SWEEPING ACROSS THE
BASIN.

CARIBBEAN SEA...
AN UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE
WESTERN CARIBBEAN NEAR 13N78W AN IS PROVIDING FOR AN OVERALL
DIFFLUENT ENVIRONMENT S OF 16N W OF 74W. WITH LOW-LEVEL MOISTURE
CONVERGENCE MAXIMIZING AS WELL OVER THE SW CARIBBEAN...SCATTERED
SHOWERS AND TSTMS ARE OCCURRING S OF 18N W OF A LINE FROM 18N84W
TO THE NORTHERN COLOMBIA COAST NEAR 11N74W...INCLUDING INLAND
PORTIONS OF NICARAGUA AND EASTERN HONDURAS. CLOSE PROXIMITY OF
THE MONSOON TROUGH AXIS ALONG 10N IS ALSO ENHANCING CONVECTION
OCCURRING ACROSS PANAMA AND COSTA RICA. FARTHER EAST...A
TROPICAL WAVE IS ANALYZED ALONG 72W WITH NO SIGNIFICANT
CONVECTION OCCURRING IN THE VICINITY OF THE WAVE AXIS AT THIS
TIME. FINALLY...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NORTH OF
PUERTO RICO NEAR 21N66W AND IS PROVIDING A FAVORABLE UPPER LEVEL
DIFFLUENT ATMOSPHERE ON THE EASTERN AND SOUTHEASTERN PERIPHERY
OF THE UPPER LEVEL LOW. MOIST SOUTHWESTERLY UPPER LEVEL FLOW
ALOFT IS FUELING SCATTERED SHOWERS AND WIDELY SCATTERED TSTMS
ACROSS THE EASTERN CARIBBEAN THIS EVENING E OF 67W. THE
STRONGEST CONVECTION REMAINS ACROSS THE NORTHERN LEEWARD ISLANDS
IN THE VICINITY OF 18N63W.

HISPANIOLA...
CURRENTLY A FEW ISOLATED SHOWERS ARE NOTED ACROSS THE SOUTHERN
COAST OF THE ISLAND BUT THESE ARE EXPECTED TO DIMINISH WITH THE
LOSS OF DAYTIME HEATING. WATER VAPOR IMAGERY INDICATES A
RELATIVELY DRY AND STABLE AIRMASS ALOFT WHICH WILL PROVIDE FOR
MOSTLY CLEAR SKIES AND FAIR CONDITIONS OVERNIGHT INTO EARLY
TUESDAY. HISPANIOLA LIES ON THE SOUTHWESTERN PERIPHERY OF A
MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 21N66W AND THIS LOW IS
EXPECTED TO SLOWLY DRIFT SOUTHWEST THROUGH TUESDAY. MIDDLE TO
UPPER LEVEL MOISTURE AND CLOUDINESS IS EXPECTED TO GRADUALLY
FILTER IN ACROSS THE ISLAND ON TUESDAY WITH A HIGHER POTENTIAL
FOR AFTERNOON AND EVENING ISOLATED SHOWERS AND TSTMS.

ATLANTIC OCEAN...
SOUTHWEST UPPER LEVEL FLOW IS NOTED ON WATER VAPOR IMAGERY OVER
A PORTION OF THE SW NORTH ATLC BETWEEN UPPER LEVEL TROUGHING
OVER THE CENTRAL CONUS AND AN ANTICYCLONIC CIRCULATION CENTERED
OVER THE BAHAMAS NEAR 25N75W. MOISTURE PRIMARILY REMAINS TO THE
NORTH OF A COLD FRONT ANALYZED FROM 32N68W TO 31N75W WHERE IT
BECOMES STATIONARY TO THE FLORIDA PENINSULA NEAR CAPE CANAVERAL.
ISOLATED SHOWERS ARE OCCURRING WITHIN 180 NM NORTH OF THE FRONT.
TO THE SOUTHEAST OVER THE REMAINDER OF THE SW NORTH ATLC...A
MIDDLE TO UPPER LEVEL LOW IS CENTERED NORTH OF PUERTO RICO NEAR
21N66W THAT SUPPORTS A LARGE AREA OF MIDDLE TO UPPER LEVEL
DIFFLUENCE SE AND E OF THE UPPER LEVEL LOW GENERATING SCATTERED
SHOWERS AND WIDELY SCATTERED TSTMS FROM 17N-25N BETWEEN 58W-68W.
TO THE NORTHEAST OF THIS CONVECTION...TROPICAL STORM LORENZO IS
CENTERED IN THE VICINITY OF 29N55W AND CONTINUES TO TRACK NORTH-
NORTHEAST. OTHERWISE...ACROSS THE CENTRAL AND EASTERN ATLC...A
SURFACE RIDGE REMAINS DOMINATE ANCHORED BY A 1019 MB HIGH
CENTERED NEAR 28N46W. FAIR WEATHER CONDITIONS STRETCH FROM THIS
HIGH CENTER EASTWARD TO THE CANARY ISLANDS.

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

$$
HUFFMAN

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