[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 041731
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON JUL 04 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.

...SPECIAL FEATURES...

TROPICAL DEPRESSION THREE WAS NEAR 20.7N 89.2W AT 1500 UTC ABOUT
55 MILES SE OF PROGRESO MEXICO MOVING NW 11 KT. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1010 MB AND THE MAXIMUM SUSTAINED
WIND SPEED IS 25 KT GUSTING TO 35 KT. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
AND/OR MIATCPAT3/WTNT33 KNHC FOR MORE DETAILS.  SURFACE
OBSERVATIONS INDICATE THAT THE CENTER MAY BE EMERGING OR
REFORMING OFFSHORE OF THE N COAST OF YUCATAN WITH SLY WINDS
OBSERVED THROUGHOUT THE PENINSULA.  THE UPPER ENVIRONMENT IS
VERY FAVORABLE FOR FURTHER DEVELOPMENT WITH AN ANTICYCLONE
ALMOST SITTING RIGHT ON TOP OF BROAD LOW-LEVEL CIRCULATION.
SCATTERED SHOWERS AND TSTMS ARE OVER THE SOUTHERN GULF AND
YUCATAN FROM 20N-25N BETWEEN 84.5W-89.5W

A STRONG TROPICAL WAVE LIES ACROSS THE LESSER ANTILLES WITH A
WEAK 1012 MB LOW PRESSURE CENTER IN THE SOUTHERN WINDWARD
ISLANDS W 15-20 KT.  PRESSURES CONTINUE TO FALL IN THE AREA WITH
SLY WINDS NOTED IN THE WINDWARDS S OF GRENADA AND ELY WINDS AT
BARBADOS.  THERE ARE BANDING FEATURES ESPECIALLY IN THE E
SEMICIRCLE WITH ANTICYCLONIC FLOW ALOFT PROVIDING AN ENVIRONMENT
CONDUCIVE TO FURTHER DEVELOPMENT.  SCATTERED SHOWERS AND A FEW
TSTMS ARE S OF 15N BETWEEN 56W-65W WITH WIDELY SCATTERED
MODERATE CONVECTION FROM 15N-19N BETWEEN 54W-60W APPROACHING
THE LEEWARD ISLAND.  COMPUTER MODELS SUGGEST THIS WAVE HAS THE
POTENTIAL TO EVENTUALLY DEVELOP INTO A TROPICAL CYCLONE AS WIND
SHEAR IS FORECAST TO REMAIN WEAK DURING ITS TREKS WESTWARD THRU
THE CARIBBEAN.  REGARDLESS OF DEVELOPMENT... HEAVY RAIN IS
LIKELY ACROSS THE LESSER ANTILLES ESPECIALLY IN THE WINDWARD
ISLANDS FOR THE NEXT COUPLE DAYS WITH INCREASED MOISTURE NOTED S
OF 15N W OF 50W.

...TROPICAL WAVES...

E ATLC WAVE ADDED ALONG 21W S OF 18N MOVING W 10-15 KT.  THE
SOUNDING FROM DAKAR INDICATED THE WAVE PASSED LATE YESTERDAY.
SATELLITE PICTURES SHOW A LARGE CIRCULATION IN THE LOW CLOUDS
THOUGH THERE IS NO DEEP CONVECTION.

CENTRAL ATLC TROPICAL WAVE IS ALONG 45W S OF 16N MOVING W 15
KT.  THE WAVE IS NOT PARTICULARLY WELL-DEFINED WITH A LITTLE
BUMP NORTHWARD IN THE ITCZ AT BEST MARKING THE WAVE'S POSITION.
MOISTURE AND SHOWERS ASSOCIATED WITH THE WAVE IS FORECAST TO
REACH THE EASTERN CARIBBEAN ISLANDS BY LATE THU.

...ITCZ...

ITCZ AXIS IS ALONG 13N16W 8N26W 8N38W 12N56W.  ISOLATED MODERATE
WITHIN 60 NM OF 11N53W AND 10N23W.

...DISCUSSION...

GULF OF MEXICO...
ATTENTION IS FOCUSED TO T.D. THREE WHICH APPEARS TO BE MOVING
INTO THE SOUTHERN GULF THIS AFTERNOON.  THE PLAYERS IN THE
STEERING OF THE CYCLONE ARE A MID/UPPER TROUGH ALIGNED FROM SW
LOUISIANA TO NE MEXICO AND A BUILDING MID/UPPER HIGH WITH ONE
CENTER OVER THE NW BAHAMAS AND ANOTHER CENTER NEAR 24N86W CLOSER
TO THE DEPRESSION.  MOST MODEL GUIDANCE SUGGEST THE TRACK WILL
BE BETWEEN THE TROUGH AND THE HIGH WITH THE CYCLONE GENERALLY
STAYING UNDER LIGHT SHEAR FOR A DAY OR TWO UNDER THE SW FLANK OF
AN UPPER RIDGE.  MOISTURE FROM THE SYSTEM IS JUST A COUPLE
HUNDRED MILES SE OF LOUISIANA AND SHOULD BEGIN TO AFFECT THE
CENTRAL GULF COAST OVERNIGHT WITH WIDELY SCATTERED
SHOWERS/TSTMS.  THE NW GULF HAS MODERATE/STRONG SUBSIDENCE ALOFT
WHICH IS SUPPRESSING MOST CONVECTION WHILE TYPICAL SEA-BREEZE
CONVECTION HAS BEGUN IN EARNEST OVER LOUISIANA EASTWARD THRU THE
FLORIDA PANHANDLE.  CONDITIONS LOOK MUCH DRIER THAN AVERAGE IN S
FLORIDA FOR THE NEXT FEW DAYS AS SUBSIDENCE/RIDGING BUILDS IN
THE WAKE OF THE DEPRESSION.

CARIBBEAN SEA...
EFFECTS FROM THE T.D. ARE WANING AS THE SYSTEM PULLS OFF TO THE
NW.  A WET DAY SHOULD OCCUR IN YUCATAN AND IN THE FAR NW
CARIBBEAN WITH LOW-LEVEL CONVERGENCE LIKELY FIRING STORMS FOR
MOST OF THE DAY THRU THE YUCATAN CHANNEL INTO YUCATAN.  STRONG
SUBSIDENCE IS ASSOCIATED WITH AN INVERTED MID/UPPER TROUGH
MOVING QUICKLY WESTWARD NEAR CENTRAL AMERICA TO THE CAYMAN
ISLANDS AND SHOULD RESULT IN A FEW LESS TSTMS OVER CENTRAL
AMERICA TODAY.  THE DRY CONDITIONS W OF 70W ARE BEING QUICKLY
ERODED AWAY BY MOISTURE FROM THE ADVANCING TROPICAL WAVE IN THE
FAR SE CARIBBEAN WITH ELY WINDS COVERING THE REGION.  INCREASING
RAIN CHANCES ARE LIKELY FOR THE LEEWARD ISLANDS OVERNIGHT INTO
TOMORROW WITH THE BRUNT OF THE MOISTURE REACHING HISPANIOLA BY
WED.  THE WEATHER LOOKS QUITE WET IN THE WINDWARD ISLANDS FOR AT
LEAST THE NEXT 3 DAYS AS DEEP-LAYERED MOISTURE IS FORECAST TO
REMAIN HIGH.

ATLANTIC OCEAN...
UPPER RIDGING HAS BUILD ACROSS THE W ATLC AS AN ANTICYCLONE IS
POSITIONED NEAR THE NW BAHAMAS WITH AN AXIS FROM CENTRAL FLORIDA
TO BERMUDA.  A THIN TROUGH IS E OF THE HIGH WITH THE TROUGH
RUNNING FROM 30N467W SW THRU PUERTO RICO.  A LITTLE BIT OF
COOLER AIR ALOFT CONTINUES TO SUPPORT A FEW TSTMS WITHIN 60 NM
OF THE TROUGH AXIS NE OF 22N60W.  OTHERWISE MID/UPPER RIDGING
CONTROLS THE CENTRAL ATLC WHILE A WEAK TROUGH DIPS INTO THE NE
ATLC NW OF THE CANARY ISLANDS.  STRONG SUBSIDENCE IS KEEPING THE
AREA NE ATLC RATHER DRY WITH THE TYPICAL SCATTERED TO BROKEN
STRATOCUMULUS OBSERVED.  FARTHER S...UPPER RIDGING COVERS THE
AREA WITH ONE ANTICYCLONE NEAR 15N53W AND THE OTHER ONE OVER NW
MAURITANIA.  THERE IS A WEAK INVERTED TROUGH BETWEEN THE RIDGES
ALONG 38W WITH MODERATE/STRONG SUBSIDENCE AND DRY AIR ALOFT FROM
THE CAPE VERDES TO 50W.  THE DEEP TROPICS ARE CONTROLLED BY
ANTICYCLONIC FLOW WITH RIDGING FROM W MAURITANIA TO THE SOUTHERN
LEEWARD ISLANDS.  AT THE SURFACE... LARGE 1033 MB HIGH NEAR
39N38W DOMINATES THE AREA EXCEPT FOR TROPICAL WAVES ALONG ITS
SOUTHERN PERIPHERY.  VERTICAL WIND SHEAR IS MUCH BELOW AVERAGE
EVERYWHERE ACROSS THE DEEP TROPICS S OF 20N.. AIDING THE
POSSIBLE DEVELOPMENT OF THE SE CARIBBEAN WAVE.

$$
BLAKE

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