[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 191800
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...TROPICAL WAVES...

TROPICAL WAVE OVER THE CENTRAL ATLC ALONG 45W/46W 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 WELL AHEAD OF THE WAVE AXIS.

TROPICAL WAVE NEARING THE LESSER ANTILLES ALONG 59W S OF 15N
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 FROM PASSAGE THROUGH THE CAYENNE UPPER
AIR SOUNDING NEAR 0600 UTC JUNE 18.  NEARBY SCATTERED MODERATE
CONVECTION APPEARS MORE DIRECTLY RELATED TO THE SURGE FROM
8N-13N BETWEEN 59W AND 65W INCLUDING PORTIONS OF THE WINDWARD
ISLANDS AND TRINIDAD/TOBAGO.

TROPICAL WAVE OVER THE CENTRAL CARIBBEAN ALONG 68W S OF 18N
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 ALONG 89W 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 12N10W 7N30W 7N40W 10N50W 9N60W THE
OVER N PORTIONS OF VENEZUELA AND COLOMBIA.  SCATTERED MODERATE
CONVECTION WITHIN 125 NM N OF ITCZ BETWEEN 25W-36W. SCATTERED
MODERATE CONVECTION WITHIN 125 NM EITHER SIDE OF ITCZ FROM
51W-60W.

...DISCUSSION...

GULF OF MEXICO...
UNSEASONABLY HIGH AMPLITUDE MIDDLE TO UPPER LEVEL TROUGH REMAINS
OVER THE E UNITED STATES AND N GLFMEX WITH ASSOCIATED SUBSIDENCE
COVERING THE GLFMEX AND FLORIDA POLEWARD OF 25N. FURTHER
S...DEEP-LAYERED SW FLOW IS ADVECTING TROPICAL MOISTURE NWD OVER
THE SE GLFMEX AND FLORIDA CREATING A SHARP GRADIENT IN AVAILABLE
MOISTURE. 1200 UTC SOUNDINGS SHOWED PRECIPITABLE WATER VALUES
OF 1.40 AND 2.59 FROM JACKSONVILLE FL AND BELIZE RESPECTIVELY.
SATELLITE IMAGERY INDICATES THIS DEEP TROPICAL MOISTURE IS
GRADUALLY OVERSPREADING S FLORIDA GENERATING DEVELOPING
SHOWERS/TSTMS. THIS TREND IS EXPECTED TO CONTINUE THROUGH THE
NEXT 2 DAYS RESULTING IN A RATHER WET AND STORY PERIOD THROUGH
AT LEAST MONDAY EQUATORWARD OF A LINE FROM THE BAY OF CAMPECHE
TO FLORIDA NEAR LAKE OKEECHOBEE. ELSEWHERE OVER THE
GLFMEX...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 TO NUMEROUS
THUNDERSTORMS CURRENT EXIST WITHIN 200 NM S OF THE LOW LEVEL
TROUGH WITH WIDELY SCATTERED SHOWERS/TSTMS WITHIN 100 NM N OF
THE TROUGH.  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.  THIS FEATURE WILL CONTINUE TO PRODUCE
SUBSIDENCE AND DRYING ALOFT TO ITS WEST AS IT MOVES OVER THE
CENTRAL CARIBBEAN TO ABOUT 70W BY MON AFTERNOON.  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.  THIS ENVIRONMENT SHOULD
SUPPRESS CONVECTION TO POINTS S OF 10N IN ASSOCIATION WITH A
TROPICAL WAVE APPROACHING THE AREA ALONG 59W.

ATLANTIC OCEAN...
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 34N25W TO THE LEEWARD ISLANDS.  OVER THE FAR E
ATLC...THE ADVANCING MID-OCEANIC TROUGH HAS WEAKENED THE
PREVIOUSLY WELL-ESTABLISHED UPPER LEVEL RIDGE.  THE 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.  THE BULK OF THE ACTIVE
SHOWERS/TSTMS CONTINUE TO BE FOCUSED OVER THE W ATLC IN
ASSOCIATION WITH THE STRONG TROUGH ALONG THE E UNITED STATES E
COAST.  CURRENTLY...A DEVELOPING LINE OF SCATTERED SHOWERS AND
THUNDERSTORMS IS NOTED WITHIN 125 NM EITHER SIDE OF A LINE FROM
W CUBA OVER THE N BAHAMAS TO JUST W OF BERMUDA NEAR 32N69W.
THIS OVERALL ACTIVITY WILL LIKELY PERSIST DURING THE NEXT 12-24
HOURS PRODUCING GUSTY WINDS AND LOCALLY HEAVY RAINFALL.   AT THE
SURFACE...THE SUBTROPICAL RIDGE CONTINUES TO STRENGTHEN FROM THE
AZORES TO THE S BAHAMAS.  THIS HAS RESULTED IN INCREASING TRADES
OVER THE CARIBBEAN AND TROPICAL ATLC S OF 20N.  FINALLY...A
LARGE OUTBREAK OF AFRICAN DUST CONTINUES TO PROPAGATE WESTWARD
ACROSS THE TROPICAL ATLC WATERS NOW SPANNING FROM THE E
CARIBBEAN TO AFRICA.  HAZE AND

$$
RHOME


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