[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 192341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN JUN 19 2005

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
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 OVER THE CENTRAL ATLC IS ALONG 47W S OF 16N MOVING
WEST 15-20 KT. THE WAVE CONTINUES TO DEMONSTRATE A LARGE AND
WELL-DEFINED CYCLONIC ENVELOPE IN SATELLITE IMAGERY.
HOWEVER...THE PRESENCE OF DRY/STABLE AIR ASSOCIATED WITH A
AFRICAN DUST SURGE IS LIMITING DEEP CONVECTIVE ACTIVITY.
CURRENTLY...THE ONLY ACTIVITY IN THE VICINITY OF THE WAVE IS
WITHIN THE ITCZ.

TROPICAL WAVE NEARING THE LESSER ANTILLES IS ALONG 60W S OF 13N
MOVING WEST NEAR 15 KT.  THE EXACT WAVE LOCATION IS DIFFICULT TO
DISCERN IN SATELLITE IMAGERY DUE TO ITS INTERACTION WITH THE
LEADING EDGE OF AN AFRICAN DUST SURGE.  THE CURRENT POSITION IS
BASED UPON EXTRAPOLATION.  SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS FROM EQ-13N BETWEEN 56W-63W.

TROPICAL WAVE OVER THE CENTRAL CARIBBEAN IS ALONG 69W S OF 16N
MOVING WEST 10-15 KT. THIS WAVE IS LOCATED NEAR THE BASE OF AN
UPPER LOW RETROGRADING ACROSS THE E CARIBBEAN.  AS A
RESULT...UPPER LEVEL CONFLUENCE AND DRY/STABLE AIR ALOFT IS
SUPPRESSING DEEP CONVECTIVE ACTIVITY AND ONLY A FEW ISOLATED
SHOWERS/TSTM ACCOMPANY THE WAVE.

TROPICAL WAVE OVER CENTRAL AMERICA IS ALONG 90W S OF 16N MOVING
WEST 10-15 KT. THE N PORTION OF THE WAVE APPEARS TO BE
INTERACTING WITH A CONVECTIVELY ACTIVE LOW LEVEL TROUGH
EXTENDING FROM THE YUCATAN PENINSULA NEWD OVER W CUBA.   AS A
RESULT...THE SATELLITE SIGNATURE N OF CENTRAL AMERICA IS WEAK
AND THE PRESENT POSITION IS BASED UPON LOW LEVEL TURNING OVER
THE E PACIFIC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 10N14W 8N30W 10N47W 7N55W 8N60W.
WIDELY SCATTERED MODERATE CONVECTION IS FROM 6N-9N BETWEEN
13W-29W.  SCATTERED MODERATE CONVECTION IS FROM 9N-11N BETWEEN
31W-37W...AND FROM 12N-14N BETWEEN 45W-49W.

...DISCUSSION...

GULF OF MEXICO...
A SURFACE TROUGH EXTENDS FROM S FLORIDA TO THE YUCATAN
PENINSULA.  WINDS N OF THE TROUGH ARE FROM THE NE AT 10 KT.
SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OVER S
FLORIDA AND THE STRAITS OF FLORIDA FROM 23N-27N BETWEEN
80W-84W.  NUMEROUS STRONG CONVECTION IS MOSTLY INLAND OVER S
MEXICO AND GUATEMALA FROM 14N-18N BETWEEN 88W-96W.  IN THE UPPER
LEVELS...UNSEASONABLY HIGH AMPLITUDE MIDDLE TO UPPER LEVEL
TROUGH REMAINS OVER THE E UNITED STATES AND N GLFMEX WITH
ASSOCIATED SUBSIDENCE COVERING THE GULF OF MEXICO AND FLORIDA
POLEWARD OF 25N. FURTHER S...DEEP-LAYERED SW FLOW IS ADVECTING
TROPICAL MOISTURE NWD OVER THE SE GULF OF MEXICO AND FLORIDA
CREATING A SHARP GRADIENT IN AVAILABLE MOISTURE.  THIS TREND IS
EXPECTED TO CONTINUE THROUGH THE NEXT 2 DAYS RESULTING IN A
RATHER WET PERIOD THROUGH AT LEAST MONDAY EQUATORWARD OF A LINE
FROM THE BAY OF CAMPECHE TO FLORIDA NEAR LAKE OKEECHOBEE.
ELSEWHERE OVER THE GULF OF MEXICO...CONFLUENT FLOW AND
SUBSIDENCE W OF THE UPPER TROUGH AXIS SHOULD MAINTAIN DRY
CONDITIONS WITH BELOW NORMAL CLOUDINESS AND SHOWERS/TSTMS.

CARIBBEAN SEA...
A RATHER ACTIVE PATTERN IS IN PLACE OVER THE NW CARIBBEAN
COURTESY OF A LOW LEVEL TROUGH FROM THE YUCATAN PENINSULA TO THE
FLORIDA STRAITS AND A SHARP MIDDLE TO UPPER LEVEL RIDGE FROM
MEXICO TO THE CENTRAL BAHAMAS.  SCATTERED MODERATE TO ISOLATED
STRONG CONVECTION IS FROM 17N-21N BETWEEN 81W-85W.
EXPECT LOCALLY HEAVY RAINFALL AND POSSIBLE FLOODING WITH THIS
ACTIVITY PRIOR TO IT SPREADING INTO THE SE GLFMEX LATE MON INTO
TUE.  FURTHER E...MID-OCEANIC TROUGH HAS FRACTURED FORMING AN
UPPER LOW NOW RETROGRADING ACROSS THE E CARIBBEAN N OF THE ABC
ISLANDS NEAR 14N67W. THIS FEATURE WILL CONTINUE TO PRODUCE
SUBSIDENCE AND DRYING ALOFT TO ITS WEST AS IT MOVES OVER THE
CENTRAL CARIBBEAN.  THIS SETUP WILL SUPPRESS TYPICAL
SHOWERS/TSTM ACTIVITY OVER THE CENTRAL CARIBBEAN DURING THE NEXT
12-24 HOURS WHILE DIFFLUENCE E OF THE UPPER LOW WILL PRODUCE
SOME INSTABILITY AND ENHANCED SHOWERS/TSTMS OVER THE E CARIBBEAN
PRIOR TO THE ARRIVAL OF AN AFRICAN DUST SURGE CURRENTLY ENTERING
THE AREA FROM PUERTO RICO TO THE WINDWARD ISLANDS.  THIS SURGE
WILL CONTINUE TO SPREAD WESTWARD OVER THE E CARIBBEAN AT 20-25
KT PRODUCING DRY AIR...DUST...AND HAZE IN ITS WAKE.

ATLANTIC OCEAN...
A SURFACE TROUGH IS OVER THE BAHAMAS FROM 29N74W TO 26N80W.
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 25N-29N BETWEEN
73W-80W.  THIS OVERALL ACTIVITY WILL LIKELY PERSIST DURING THE
NEXT 12-24 HOURS PRODUCING GUSTY WINDS AND LOCALLY HEAVY
RAINFALL. THE SUBTROPICAL RIDGE CONTINUES TO STRENGTHEN AND
DOMINATES THE ATLANTIC FROM THE AZORES TO THE S BAHAMAS. THIS
HAS RESULTED IN INCREASING TRADES OVER THE CARIBBEAN AND
TROPICAL ATLC S OF 20N. A LARGE OUTBREAK OF AFRICAN DUST
CONTINUES TO PROPAGATE WESTWARD ACROSS THE TROPICAL ATLC WATERS
NOW SPANNING FROM THE E CARIBBEAN TO AFRICA. IN THE UPPER
LEVELS... A SHARP UPPER LEVEL TROUGH-RIDGE-TROUGH PATTERN
PREVAILS OVER THE W TWO-THIRDS OF THE ATLC WATERS WITH A HIGH
AMPLITUDE TROUGH OVER THE E UNITED STATES AND W ATLC WATERS W OF
BERMUDA...RIDGE OVER THE CENTRAL ATLC EXTENDING FROM HISPANIOLA
NEWD TO BEYOND 32N50W...AND THE MID-OCEANIC TROUGH EXTENDING
FROM JUST E OF THE AZORES ALONG 32N25W TO THE LEEWARD ISLANDS.
OVER THE TROPICAL E ATLANTIC A RIDGE REMAINS WELL DEFINED S OF
20N WITH MEAN AXIS EXTENDING E/W ALONG 12N/13N.  RESULTING
DEEP-LAYERED ELY FLOW DOMINATES MUCH OF THE TROPICAL BELT E OF
THE LESSER ANTILLES.

$$
FORMOSA


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