[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 172345
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN 17 OCT 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA... GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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 IN THE E CARIBBEAN IS ALONG 68W/69W S OF 18N
MOVING W 10 KT.  WAVE IS FOLLOWED BY AN INCREASE IN SHOWERS WITH
ISOLATED ACTIVITY N OF 15N E OF 70W IN THE CARIBBEAN SEA.

...ITCZ...
ITCZ AXIS IS ALONG 8N11W 6N25W 10N40W 9N61W.  WIDELY SCATTERED
MODERATE FROM 4N-8.5N BETWEEN 30W-40W.  ISOLATED MODERATE WITHIN
75 NM OF LINE 7N12W 5N24W 6N30W.

...DISCUSSION...
GULF OF MEXICO...
THE GULF IS RATHER QUIET WITH ANY REMAINS OF THE STATIONARY COLD
FRONT OVER CUBA WITH ISOLATED SHOWERS.  RETURN FLOW IS
CONTINUING ALONG TEXAS INTO LOUISIANA WITH A FEW ISOLATED
SHOWERS NEAR GALVESTON.  HIGH PRESSURE CONTROLS THE AREA FROM A
1019 MB CENTER OVER THE EXTREME NW ATLC.  VERY DRY MID/UPPER
LEVEL AIR IS IN PLACE WITH A WEAK MID/UPPER TROUGH FROM THE
FLORIDA KEYS TO YUCATAN... DEMARCATING INCREASING MOISTURE OVER
THE CARIBBEAN FROM DRIER AIR IN THE MID/UPPER LEVELS OVER THE
GULF.  NO SIGNIFICANT FRONTS ARE ON THE HORIZON WITH WARM INDIAN
SUMMER CONDITIONS LIKELY THIS WEEK IN THE GULF COAST STATES.

CARIBBEAN SEA AND SW ATLC W OF 60W...
SPRAWLING MID/UPPER HIGH CENTERED JUST S OF HISPANIOLA IS THE
MAIN SYNOPTIC FEATURE AS ITS ANTICYCLONIC FLOW COVERS THE AREA.
STATIONARY FRONT LIES ON THE NW SIDE OF THE HIGH FROM NEAR
32N60W SW INTO THE CENTRAL BAHAMAS WITH WIDELY SCATTERED WEAK/
MODERATE CONVECTION AND A FEW TSTMS WITHIN 150 NM OF THE FRONT E
OF 76W.  UPPER WINDS ARE PARALLELING THE FRONT WITH A SLOW
DISSIPATION LIKELY AS ITS REMNANTS OVER THE EARLY PART OF THE
WEAK SAG SOUTHWARD.  FAR SW...WEAKENING CONVECTION IS OVER THE
W CARIBBEAN WITH WEAK UPPER TROUGHINESS IN THE AREA SPARKING
SOME DIURNAL ACTIVITY.  VERY DRY AIR IS IN THE MID/UPPER LEVELS
E OF 75W.. KEEPING DEEP CONVECTION TO A MINIMUM WITH ONLY
TRADEWIND SHOWERS PRESENT.   MID/UPPER HIGH IS EXPECTED TO SINK
SOUTHWARD AS A BROAD TROUGH INTRUDES FROM THE N....CAUSING A
WETTER WEATHER PATTERN OVER THE GREATER ANTILLES INTO THE NE
LEEWARD ISLANDS BY MID-WEEK.

SW ATLC E OF 60W AND TROPICAL ATLC...
TROUGH/RIDGE/TROUGH PATTERN REMAINS BUT IS FRACTURING IN THE
TROPICAL ATLC.  MID-LATITUDE TROUGH DIGS FROM 32N39W TO 23N45W
WITH A CUTOFF MID/UPPER LOW FORMING ALONG A TROUGH FROM 20N53W
TO 9N57W.  THIS CUTOFF LOW IS LIKELY TO HAVE LITTLE MOVEMENT
THRU MOST OF THE WEEKEND BUT SHOULD CAUSE HEAVY RAINS NEAR AND E
OF THE AXIS OVER THE OPEN WATER.  ISOLATED MODERATE IS N OF 23N
BETWEEN 29W-39W WITH BROKEN/OVERCAST SKIES AND ISOLATED SHOWERS
IN THE DEEP TROPICS FROM N OF 11N BETWEEN 40W-54W.  THESE RAIN
AREAS ARE DUE TO SYNOPTIC LIFT... ESPECIALLY IN THE MID-LATITUDE
SYSTEM... WITH WEAK TROPICAL WAVE ENERGY IN THE DEEP TROPICS
ENHANCING SHOWERS.  COLD FRONT IS ALONG 31N27W TO 23N40W WITH
UPPER ENERGY FORCING A FEW TSTMS WITHIN 75 NM OF 27.5N32W.
MID/UPPER HIGH IS NEAR 9N35W WITH RIDGING NE TO 31N20W.
INCREASING HIGH CLOUDS/ MOISTURE IN PRESENT THE MID/UPPER LEVELS
ROTATING AROUND THE HIGH FROM NEARBY TSTMS AND LARGE-SCALE
LIFT.   OTHERWISE TROUGHING IS OVER THE E ATLC E OF 20W FROM A
TROUGH OVER E MAURITANIA INTO MALI WITH STRONG SUBSIDENCE AROUND
THE SW BASE OF THE TROUGH NEAR AND E OF THE CAPE VERDES.

$$
BLAKE

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