[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 202344
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN OCT 20 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.

...TROPICAL WAVES...
TROPICAL WAVE EXTENDS FROM 07N34W TO 16N34W MOVING W AT 10-15
KT. THE WAVE REMAINS EMBEDDED WITHIN THE MONSOON TROUGH AND ITCZ
AXIS AND ALSO WITHIN VERY BROAD SURFACE TO 700 MB TROUGHING
BETWEEN 30W-40W. ENERGY FROM THE WAVE IS CONTINUING TO FRACTURE
ENERGY DUE TO AN UPPER LEVEL TROUGH AXIS NOTED ON WATER VAPOR
IMAGERY FROM 20N26W TO 12N48W. VERY DRY AIR ALOFT IS NOTED IN
THE VICINITY OF THE TROUGH AXIS AND AREAS TO THE NORTH OF THE
AXIS BETWEEN 30W-50W THUS ANY SIGNIFICANT DEEP CONVECTION WITH
THE WAVE IS LIMITED AT THIS TIME. ISOLATED MODERATE CONVECTION
IS FROM 07N-12N BETWEEN 27W-39W.

TROPICAL WAVE EXTENDS FROM 09N68W TO 17N67W MOVING W AT 10-15
KT. THE WAVE CONTINUES TO BE SOMEWHAT DIFFICULT TO TRACK GIVEN
THAT UPPER LEVEL WESTERLIES DOMINATE OVER THE CARIBBEAN SEA AND
THAT THE WAVE LACKS ANY STRONG 700 MB RELATIVE VORTICITY
SIGNATURE IN GLOBAL MODEL DATA. HOWEVER...VERY WEAK SURFACE TO
700 MB TROUGHING EXISTS BETWEEN 62W-70W WITH MOST OF THE
CONVECTION OCCURRING EAST OF THE AXIS ACROSS THE LEEWARD ISLANDS
THIS EVENING AND ASSOCIATED WITH MIDDLE TO UPPER LEVEL
DIFFLUENCE ON THE SOUTHEAST PERIPHERY OF AN UPPER LEVEL LOW
CENTERED NORTH OF PUERTO RICO NEAR 22N65W. NO SIGNIFICANT
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 15N17W TO
10N20W TO 07N33W. THE INTERTROPICAL CONVERGENCE ZONE AXIS
EXTENDS FROM 07N35W TO 08N49W. ASIDE FROM THE CONVECTION
ASSOCIATED WITH THE TROPICAL WAVE ALONG 34W...SCATTERED MODERATE
CONVECTION IS FROM 05N-08N BETWEEN 21W-26W. ISOLATED MODERATE
CONVECTION IS FROM 08N-11N BETWEEN 41W-51W.

...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 WESTERN CONUS AND AN UPPER LEVEL ANTICYCLONE
CENTERED OVER THE YUCATAN CHANNEL NEAR 22N85W. WHILE STRONGER
UPPER LEVEL DYNAMICS ASSOCIATED WITH THE TROUGH REMAIN OVER
NORTHERN MEXICO AND SECONDARY ENERGY OVER THE INTERMOUNTAIN
WEST...A STATIONARY FRONT IS ANALYZED FROM THE CENTRAL FLORIDA
PENINSULA NEAR 28N82W SW TO 24N91W WHERE THE FRONT BECOMES WARM
TO 21N95W. THE FRONT IS FAIRLY PRECIPITATION-FREE THIS
EVENING...HOWEVER MULTI-LAYERED CLOUDINESS INCREASES ACROSS THE
WESTERN GULF W OF 90W WITH POSSIBLE ISOLATED SHOWERS OCCURRING S
OF 27N W OF 92W AS THE WARM FRONT SLOWLY LIFTS NORTH. BY LATE
MONDAY INTO EARLY TUESDAY THE NEXT COLD FRONT IS FORECAST TO
EMERGE OFF THE TEXAS AND LOUISIANA GULF COAST SHIFTING WINDS
NORTHERLY AS THE COLD FRONT CONTINUES SWEEPING ACROSS THE BASIN
THROUGH LATE WEDNESDAY.

CARIBBEAN SEA...
AN UPPER LEVEL TROUGH AXIS EXTENDS FROM OVER EASTERN CUBA NEAR
19N77W SW TO 14N85W. WATER VAPOR IMAGERY INDICATES DRY AIR ALOFT
NORTH OF THE TROUGH AXIS AND THIS IS RESULTING IN FAIRLY STABLE
CONDITIONS THIS EVENING ACROSS THE NW CARIBBEAN. A FEW ISOLATED
SHOWERS ARE HOWEVER OCCURRING OVER INLAND PORTIONS OF CUBA AND
FROM 18N-21N BETWEEN 81W-87W IN THE AREA BETWEEN THE CAYMAN
ISLANDS AND THE YUCATAN PENINSULA COAST. SOUTH OF THE TROUGH
AXIS...LOW-LEVEL MOISTURE CONVERGENCE AND UPPER LEVEL DIFFLUENCE
ARE PROVIDING AN UNSTABLE ENVIRONMENT ACROSS THE SW CARIBBEAN
AND PORTIONS OF CENTRAL AMERICA THIS EVENING. SCATTERED SHOWERS
AND TSTMS ARE OCCURRING S OF 16N BETWEEN 76W-87W...INCLUDING
INLAND PORTIONS OF NICARAGUA AND 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 68W. WHILE NO SIGNIFICANT
CONVECTION IS OCCURRING AT THIS TIME WITH THE WAVE ITSELF...A
MIDDLE TO UPPER LEVEL LOW IS CENTERED NORTH OF PUERTO RICO NEAR
23N65W 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
NW CARIBBEAN THIS EVENING N OF 14N E OF 65W. THE STRONGEST
CONVECTION REMAINS OVER THE OPEN WATERS OF THE SW NORTH ATLC IN
THE VICINITY OF 19N60W TO THE NE OF THE LEEWARD ISLANDS.

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
MONDAY. HISPANIOLA LIES ON THE SOUTHWESTERN PERIPHERY OF A
MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 23N65W AND THIS LOW IS
EXPECTED TO SLOWLY DRIFT SOUTHWEST THROUGH EARLY TUESDAY.

ATLANTIC OCEAN...
SOUTHWEST UPPER LEVEL FLOW IS NOTED ON WATER VAPOR IMAGERY OVER
MUCH OF THE SW NORTH ATLC N OF 26N W OF 68W THAT SUPPORTS A COLD
FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N74W. THE COLD
FRONT CONTINUES TO 31N77W AND BECOMES STATIONARY TO THE CENTRAL
FLORIDA PENINSULA COAST NEAR CAPE CANAVERAL NEAR 29N81W.
ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EITHER SIDE OF THE
FRONT. TO THE EAST...ANOTHER WEAKER FRONT IS ANALYZED FROM
32N69W TO 31N71W WITH A SURFACE TROUGH EXTENDING TO 29N73W.
ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 120 NM EITHER
SIDE OF THIS BOUNDARY. OVER THE REMAINDER OF THE SW NORTH
ATLC...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NORTH OF PUERTO
RICO NEAR 23N65W 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 14N-24N
BETWEEN 57W-65W. TO THE NORTHEAST OF THIS CONVECTION...A SURFACE
TROUGH IS ANALYZED FROM 23N56W TO 29N54W AND IS PROVIDING FOCUS
FOR SCATTERED SHOWERS AND ISOLATED TSTMS FROM 24N-28N BETWEEN
52W-61W. FINALLY...ACROSS THE CENTRAL AND EASTERN ATLC...A
SURFACE RIDGE REMAINS DOMINATE ANCHORED BY A 1021 MB HIGH
CENTERED NEAR 28N44W. FAIR WEATHER CONDITIONS STRETCH FROM THIS
HIGH CENTER EASTWARD TO THE CANARY ISLANDS THEN NE TO THE
IBERIAN PENINSULA.

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

$$
HUFFMAN


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