[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 230615
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU JUN 23 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 0000 UTC SURFACE ANALYSIS AND
SATELLITE IMAGERY THROUGH 0545 UTC.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE ALONG 23W/24W SOUTH OF 15N MOVING WEST
10-15 KT.  CLUSTERS OF TSTMS IN THE ITCZ MARK THE LOCATION OF
THE WAVE AS WELL AS LONG-TERM SATELLITE LOOPS.

W ATLC TROPICAL WAVE ALONG 46W/47W SOUTH OF 12N MOVING WEST
15 TO 20 KT. STRONG WLY WINDS ALOFT NEAR THE WAVE AXIS ARE
MAKING THE WAVE'S LOCATION DIFFICULT TO FIND. ITCZ SHOWERS AND
THUNDERSTORMS ARE NEAR THIS WAVE. THE GFS AND UKMET BOTH SUGGEST
THE WAVE MIGHT BE VERY CLOSE TO THE LESSER ANTILLES AND THAT THE
WAVE HAS BEEN MOVING FASTER THAN INITIALLY EXPECTED. SURFACE
PRESSURE FIELDS HAVE BECOME MORE CLEAR SINCE THE 1800 UTC MAP
WITH 24 HOUR PRESSURE FALLS OBSERVED IN THE WINDWARD ISLANDS
ALONG WITH THE LOWEST PRESSURES.  THE WAVE WILL LIKELY BE MOVED
W TO AT LEAST 60W ON THE NEXT MAP WITH ANOTHER WAVE ADDED IN THE
VICINITY OF 45W BASED ON GOOD AGREEMENT BETWEEN VARIOUS GLOBAL
FORECAST MODELS.  WIDELY SCATTERED SHOWERS ARE S OF 14N BETWEEN
THE WINDWARD ISLANDS AND 52W.  PLENTY OF RAIN SHOULD FALL IN THE
WINDWARD ISLANDS TONIGHT WITH MOISTURE FROM THE WAVE MOVING UP
THE LEEWARD ISLANDS TOMORROW MOVING INTO PUERTO RICO BY
OVERNIGHT FRI.

CENTRAL CARIBBEAN SEA TROPICAL WAVE RUNS FROM NORTH CENTRAL
HISPANIOLA TO 15N73W TO NORTHEASTERN COLOMBIA. UNLIKE THE WAVE
APPROACHING THE LESSER ANTILLES...THIS ONE HAS ALL THE SIGNALS
WITH PLENTY OF DEEP LAYER CONVECTIVE ACTIVITY...CURRENTLY
OVERSPREADING HISPANIOLA...A V-SHAPE ON SATELLITE AND CYCLONE
CURVATURE ON EARLIER QUIKSCAT DATA.  WIDELY SCATTERED MODERATE
CONVECTION IS FROM 16N-20N BETWEEN PUERTO RICO AND HAITI.  HEAVY
RAINS ARE LIKELY TO CONTINUE OVERNIGHT OVER HISPANIOLA WITH
POSSIBLE FLASH FLOODING/MUDSLIDES.  TSTMS ARE EXPECTED TO BEGIN
SPREADING OVER E CUBA AND THE SRN BAHAMAS ON THU AS THE WAVE
SENDS DEEP MOISTURE NWD.  STRONG TSTMS CURRENTLY OVER NW
VENEZUELA ARE PROBABLY ASSOCIATED WITH THE WAVE AS WELL.

W CARIBBEAN TROPICAL WAVE ALONG 81W S OF 17N MOVING W 15-20 KT.
THE WAVE SIGNATURE IS RATHER POOR...BUT IT DOES APPEAR TO BE
ENHANCING THE COVERAGE AND INTENSITY OF THE USUAL DAILY
CONVECTION THAT OCCURS OVER THE SW CARIBBEAN. A LARGE COMPLEX OF
WIDELY SCATTERED MODERATE/STRONG CONVECTION IS S OF 15N W OF
77W.  THE HEAVIEST ACTIVITY REMAINS OFFSHORE OF COSTA RICA NEAR
11N81.5W.

...THE ITCZ...

ITCZ ALONG 12N16W 7N30W 7N45W 10N54W 11N60W. ISOLATED MODERATE
CONVECTION IS WITHIN 75 NM OF THE AXIS BETWEEN 18W-32W WITH AN
EMERGING TSTM CLUSTER NEAR W AFRICA AT 11N15.5W.  WIDELY
SCATTERED MODERATE IS WITHIN 90 NM OF AXIS BETWEEN 35W-47W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LOW HAS FORMED IN THE SE GULF AT THE TAIL END OF A
MID/UPPER TROUGH FROM JUST OFFSHORE OF N CAROLINA THRU CENTRAL
FLORIDA. IT IS NOW ABOUT 180 NM WEST-SOUTHWEST OF SOUTH FLORIDA
PENINSULA...AND ABOUT 150 NM NORTH-NORTHEAST OF THE WESTERN TIP
OF CUBA.  AS WRITTEN EARLIER...THIS LOW IS STRONGER THAN ANY OF
THE NUMERICAL MODELS HAVE SUGGESTED. THE WEAK SFC LOW ABOUT
WEST OF TAMPA FROM THE 22/1800 UTC MAP ANALYSIS DISAPPEARED AT
23/0000 UTC. SHOWERS AND THUNDERSTORMS ARE MORE IN THE ATLANTIC
WATERS FROM CUBA TO THE NORTHERN BAHAMAS FROM 22N TO 27N BETWEEN
77W AND 80W...SKIRTING SOUTH FLORIDA AT THE SAME TIME. THIS
PRECIPITATION HAS FORMED WITH THE ASSISTANCE OF STRONG UPPER
DIFFLUENCE NEAR THE SE GULF LOW. THE UPPER LOW SHOULD MOVE
SLOWLY EASTWARD...KEEPING SOUTH FLORIDA IN HIGHER-THAN-AVERAGE
RAIN CHANCES FOR AT LEAST THE NEXT 36 HOURS.

ELSEWHERE...WEAK SFC TROF IS MOVING SLOWLY W ALONG 31N82W
27N88W 23N93W 19N94W. SCATTERED TO NUMEROUS STRONG SHOWERS AND
THUNDERSTORMS NOW COVER MEXICO FROM THE COASTAL PLAINS TO THE
SOUTH OF THE SOUTHWESTERN CORNER OF THE GULF OF MEXICO...TO THE
ISTHMUS OF TEHUANTEPEC TO 97W INCLUDING INTO THE COASTAL WATERS
OF THE EASTERN PACIFIC OCEAN NEAR 15N97W AND THE PACIFIC OCEAN
SIDE SOUTHERN COASTAL WATERS OF GUATEMALA. IT IS EASILY POSSIBLE
THAT THE GROUND IN THESE AREAS ALREADY IS RAIN-SATURATED.
UPPER LEVEL DIVERGENCE HAS BEEN DEVELOPING MIDDLE TO UPPER LEVEL
RIDGING IN THE SW GULF AND THE UPPER LOW IN THE SE GULF.  BEST
MOISTURE SHOULD SHIFT SLOWLY WESTWARD BUT THERE MIGHT BE ONE
MORE DAY OF HEAVY RAIN TOMORROW BEFORE A BIT DRIER AIR MOVES
IN.  OVER THE NORTHERN GULF COAST.. THINGS REMAIN MOSTLY DRY
WITH STRONG MID/UPPER SUBSIDENCE AND RELATIVELY DRY AIR AT ALL
LEVELS. PERHAPS BY THE WEEKEND CONDITIONS WILL RETURN IN THAT
AREA TO A MORE TYPICAL COVERAGE OF DIURNAL TSTMS.

THE CARIBBEAN SEA...
A SLOWLY-MOVING MID/UPPER LEVEL TROUGH IS LOCATED BETWEEN
JAMAICA AND HAITI NEAR 18N76W SOUTHWARD TO THE COAST OF NW
COLOMBIA. SOME MIDDLE TO UPPER LEVEL DRY AIR SURROUNDS THIS
TROUGH. DEVELOPING UPPER HIGH NEAR 17N69W IS ENHANCING THE
PRECIPITATION ASSOCIATED WITH A TROPICAL WAVE WHICH RUNS FROM
NORTH CENTRAL HISPANIOLA TO 15N73W TO NORTHEASTERN COLOMBIA.
A CENTRAL ATLANTIC MIDDLE TO UPPER LEVEL TROUGH RUNS
SOUTHWESTWARD TO ITS BASE IN THE EAST CENTRAL CARIBBEAN SEA.
AN UPPER RIDGE PROTRUDES E OF BELIZE TO JUST SW OF JAMAICA AND
THE NELY FLOW TO THE S OF THE AXIS ALONG WITH A TROPICAL WAVE
IS PROVIDING A DIFFLUENT ENVIRONMENT FOR WIDELY SCATTERED TSTMS
THAT HAVE BLOSSOMED OVER THE SW CARIBBEAN.  UPPER TROUGH IS
POKING INTO THE LEEWARD ISLANDS...KEEPING THE CONVECTION MINIMAL
THOUGH THIS SHOULD CHANGE OVERNIGHT AS DEEPER MOISTURE ENTERS
THE AREA.

THE ATLANTIC OCEAN...
A STRONG MID/UPPER LEVEL TROF IS SWINGING OFF THE SOUTHEAST
U.S.A. COAST WITH A BROAD MOISTURE PLUME PUSHING AHEAD OF IT
TO THE NORTHEAST ACROSS FLORIDA AND THE NORTHERN BAHAMAS.
AMPLIFIED UPPER LEVEL RIDGING IS BUILDING NE FROM THE E TIP OF
HISPANIOLA TO 32N56W IN THE W-CENTRAL ATLC.  MODERATE/STRONG
SUBSIDENCE W OF 50W TO THE RIDGE AXIS IS KEEPING THINGS MOSTLY
DRY. A 1020 MB SFC HIGH CONTINUES TO MOVE SLOWLY EASTWARD NEAR
28N66W. RATHER LARGE UPPER TROUGH FOR LATE JUNE CONTROLS THE
CENTRAL AND E ATLC WITH MAIN AXIS FROM 32N43W TO 22N47W SW TO
THE LEEWARD ISLANDS NEAR GUADELOUPE. ISOLATED TSTMS ARE WITHIN
120 NM OF THE TROUGH AXIS N OF 20N SUPPORTED BY THE COOLER AIR
ALOFT. A WEAKENING STATIONARY FRONT TO LOW CENTER TO SURFACE
TROUGH FROM 28N TO 34N BETWEEN 43W AND 53W IS HELPING THE
ISOLATED MODERATE SHOWERS AND THUNDERSTORMS FROM 27N TO 33N
BETWEEN 40W AND 46W. THE SUBTROPICAL JET IS RACING EWD FROM THE
CNTRL LESSER ANTILLES ALONG 15N50W 16N35W 22N28W AND FEEDS TO
THE SE OF A MID/UPPER LOW NEAR 24N33W WHICH IS LIFTING QUICKLY
TO THE NE. TO THE SOUTH OF THE JET A MID/UPPER RIDGE IS ALONG
10N/11N W OF 30W WITH ELYS SUPPORTING A FEW ITCZ TSTMS.  THE
RIDGE AMPLIFIES IN THE E ATLC ALONG 24W WITH FEWER MIDDLE CLOUDS
THAN AVERAGE AS THE SUBTROPICAL RIDGE REMAINS WEAK IN THE AREA.
SOME SAHARAN DUST IS NOTED ON VISIBLE SATELLITE PICTURES E OF
THE LESSER ANTILLES MOSTLY S OF 20N EXCEPT IN THE FAR E ATLC BUT
ITS CONCENTRATION SEEMS TO BE DIMINISHING FROM RECENT WEEKS.

$$
MT

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