[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 031044
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT SEP 03 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURE...

TROPICAL STORM MARIA IS CENTERED NEAR 23.4N 52.4W...OR ABOUT 660
NM NE OF THE NORTHERN LEEWARD ISLANDS...AT 03/0900 UTC MOVING NW
11 KT. MAXIMUM SUSTAINED WINDS ARE 45 KT WITH GUSTS TO 55 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE 1000 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC
FOR MORE DETAILS.  A VERY DEEP BURST OF CONVECTION CONTINUES
NEAR THE CENTER OF MARIA WHICH APPEARS TO BE ON AN INTENSIFYING
TREND.   AN UPPER HIGH IS LOCATED NEAR THE CYCLONE WITH
RELATIVELY LIGHT SHEAR.  MARIA COULD BECOME THE SEASON'S 5TH
HURRICANE IN A COUPLE OF DAYS WITH FORECAST LOW SHEAR AND WARM
WATERS IN ITS PATH.

...TROPICAL WAVES...

E ATLC WAVE ALONG 25W S OF 18N MOVING W 10-15 KT.  THIS IS NOT A
WELL-DEFINED WAVE WITH ONLY WEAK TURNING NOTED ON NIGHT VIS
IMAGES WHICH SUGGEST THE WAVE HASN'T PASSED THE CAPE VERDE
ISLANDS.  A RECENT QUIKSCAT SUGGESTS THE WAVE IS RIGHT OVER THE
WESTERN CAPE VERDES.  ISOLATED TSTMS FROM 11N-15N BETWEEN
22W-25W.

CENTRAL ATLC TROPICAL WAVE ADDED ALONG 39W/40W S OF 16N MOVING W
10-15 KT WITH A 1010 MB LOW ALONG THE WAVE NEAR 11N.  THIS
SYSTEM WAS CONSIDERED A SUSPECT AREA FOR DEVELOPMENT YESTERDAY
BUT HAS FALLEN APART RECENTLY.  THERE ARE STILL ISOLATED TSTMS
FROM 11N-14N BETWEEN 39W-41W ASSOCIATED WITH THE WAVE.  MOST
MODELS NOW SUGGEST LITTLE CHANCE FOR TROPICAL CYCLONE
DEVELOPMENT IN THE SHORT-TERM THOUGH THE SYSTEM WILL HAVE TO BE
WATCHED AS IT APPROACHED THE LESSER ANTILLES NEXT WEEK.  A SURGE
IN WINDS PLUS DRIER AIR IS AHEAD OF THE WAVE ALONG 10N45W 20N46W
WITH A LITTLE CONVERGENCE ON THIS BOUNDARY CAUSING ISOLATED
MODERATE CONVECTION WITHIN 60 NM OF 10N45W.

E CARIBBEAN WAVE ALONG 69W S OF 14N MOVING W 10-15 KT.  THERE IS
GREAT UNCERTAINTY IN THE WAVE POSITION WITH EXTRAPOLATION LEANED
ON HEAVILY.  THE ENVIRONMENT NEAR THE WAVE IS DRY AND
CONVECTION-FREE BUT A FEW TSTMS OVER LAND COULD BE ASSOCIATED
WITH THIS SYSTEM.

TROPICAL WAVE OVER SOUTHERN MEXICO ALONG 95W S OF 18N MOVING W
15-20 KT. THE NRN PORTION OF THE WAVE IS HELPING WIDELY
SCATTERED MODERATE TSTMS WITHIN 75 NM OF 17N96W OVER THE ISTHMUS
OF TEHAUNTEPEC.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 12N15W 13N25W 14N34W 7N45W.  THE
ITCZ IS NOT WELL-DEFINED ANYWHERE ESPECIALLY W OF 45W.
SCATTERED MODERATE WITHIN 45 NM OF LINE 6.5N11W 6N20W.  A FEW
TSTMS ARE WITHIN 60 NM OF 7N44W.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER LEVEL RIDGING LIES FROM NE FLORIDA TO SE TEXAS ACROSS
THE NRN GULF COAST WITH AN UPPER HIGH CENTERED JUST S OF LAKE
CHARLES LOUISIANA NEAR 28N93W. DEEP TROPICAL MOISTURE IS LOCATED
S OF THE RIDGE AXIS AND DURING DAYTIME HEATING SHOULD BUBBLE UP
INTO ABOVE AVERAGE TSTMS.  EARLIER SURFACE TROUGH IS VERY WEAK
AS IT MOVES FARTHER AWAY FROM ITS SOURCE OF DRY AIR OVER THE SE
UNITED STATES.  AN ISOLATED CLUSTER OF TSTMS IS NEAR 25.5N83W
WITH OTHER TSTMS S OF 23N W OF 94W... OTHERWISE THE GULF IS
QUIET.  DEWPOINTS IN THE UPPER 60S HAVE MADE THEIR WAY TO THE
GULF WATERS...A RELIEF FROM OPPRESSIVE DEWPOINTS RECENTLY IN THE
UPPER 70S.  THIS DRIER AIR IS TRYING TO MAKE ITS WAY DOWN THE
FLORIDA PENINSULA THOUGH IT REMAINS MOSTLY IN NE FLORIDA.
ENOUGH MOISTURE WILL LINGER FROM S FLORIDA TO THE BAY OF
CAMPECHE FOR TSTMS TO DEVELOP THROUGHOUT THE SRN GULF.  HOWEVER
ALL IN ALL THE NRN PART AREA WILL BE DRIER THAN AVERAGE WITH A
1023 MB HIGH OVER MISSOURI KEEPING CONTINENTAL AIR MOVING
SOUTHWARD OVER THE GULF... WITH THE EXCEPTIONS BEING S FLORIDA
AND S TEXAS.

CARIBBEAN...
ELONGATED UPPER LOW/TROUGH IS LOCATED OVER THE NW CARIBBEAN
EXTENDING FROM JUST N OF CUBA TO THE GULF OF HONDURAS.  A FEW
TSTMS ARE JUST OFFSHORE OF COZUMEL... OTHERWISE A SLIGHTLY
ENHANCED DAY OF DIURNAL TSTMS ARE EXPECTED IN YUCATAN AND W
CUBA.  AN UPPER LEVEL HIGH IS CENTERED NEAR NE NICARAGUA WITH A
LARGE AREA OF DIFFLUENCE ALOFT CENTERED OVER THE SW CARIBBEAN
WHERE THE FLOW DIVERGES BETWEEN THE HIGH AND LOW.  SCATTERED
STRONG CONVECTION IS WITHIN 60 NM OF LINE 12N74W 12N78W.
ELSEWHERE...DRY AIR AND CLEAR CONDITIONS EXTEND E OF 76W WITH
ANOTHER UPPER HIGH CENTERED S OF HISPANIOLA NEAR 16N70W. THE DRY
AIR MASS WILL SLOWLY EXPAND OVER THE ENTIRE CARIBBEAN THROUGHOUT
THE WEEKEND WITH THE POSSIBILITY OF INCREASED MOISTURE AND SOME
SHOWERS MOVING ACROSS THE WINDWARD ISLANDS LATE MON.  THE SW AND
NW CARIBBEAN SHOULD SEE THE BULK OF THE PRECIPITATION THIS
WEEKEND AS THE DRY AIR LIMITS TSTMS IN THE CENTRAL/E CARIBBEAN.

W ATLANTIC...
COMPLEX SCENARIO CONTINUES OVER THE W ATLC. AT LEAST TWO
DISTINCT SURFACE LOWS ARE OBSERVED IN SATELLITE IMAGERY AND THE
ISOBARIC ANALYSIS...A PAIR OF 1010 MB LOWS NEAR 28N70W AND A S
OF BERMUDA NEAR 30N65W.  A WEAK STATIONARY FRONT LIES FROM
31N69W TO 30N76W WITH AN EARLIER SURFACE LOW LIKELY DISSIPATED.
A TROUGH EXTENDS SW OF THE LOW NEAR BERMUDA TO S FLORIDA.  A
THIRD POSSIBLE LOW...AT LEAST AT THE MID-LEVELS... COULD BE NEAR
25N68W BUT NIGHT VIS IMAGES ARE INCONCLUSIVE.  THIS POSSIBLE LOW
IS ALONG A TROUGH EXTENDING FROM THE LOW NEAR BERMUDA TO 22N69W.
AN UPPER LOW IS LOCATED WITHIN THE SAME GENERAL REGION NEAR
31N61W WITH A TROUGH SW TO 21N69W. UPPER DIFFLUENCE IN
COMBINATION WITH THE SURFACE FEATURES IS PRODUCING SCATTERED
MODERATE CONVECTION WITHIN 75 NM OF 25N68W AND 25.5N74.5W.
LITTLE MOVEMENT IS FORECAST WITH SOME CHANCE OF TROPICAL CYCLONE
GENESIS POSSIBLE IF UPPER RIDGING DEVELOPS OVER THE AREA LIKE
SOME COMPUTER MODELS ARE SUGGESTING BUT IT WILL LIKELY BE A SLOW
PROCESS.

E & CENTRAL ATLANTIC...
TROPICAL STORM MARIA IS MOVING NWWD OVER THE CENTRAL ATLC WATERS
UNDER THE SRN FLANK OF AN UPPER HIGH NEAR 28N52W.  IT SEEMS TO
HAVE LEFT THE INFLUENCE OF AN UPPER LOW NEAR 19N57W AND COULD
EVENTUALLY BECOME A HURRICANE AS IT ENTERS HIGHER LATITUDES.
ISOLATED TSTMS ARE WITHIN 90 NM OF THE UPPER LOW WITH PLENTY OF
UPPER INSTABILITY OVER WARM WATERS.   A RATHER DEEP UPPER TROUGH
IS DIGGING INTO THE AREA FROM A LOW NEAR 35N27W WITH A TROUGH SW
TO 22N37W.  AN EARLY-SEASON COLD FRONT IS INTO THE AREA ALONG
31N28W TO 27N36W.   WIDELY SCATTERED SHOWERS/TSTMS LIE AHEAD OF
THE FRONT WITHIN 60 NM.  AHEAD OF THIS TROUGH THERE IS ANOTHER
TROUGH... RUNNING FROM 24N23W TO 17N30W.. MUCH FARTHER S THAN
AVERAGE FOR EARLY SEPT.  THIS IS PROBABLY WHY ALL THE TROPICAL
SYSTEMS IN THE DEEP TROPICS HAVE BEEN STRUGGLING E OF THE LESSER
ANTILLES.  TYPICAL UPPER RIDGING IS SPLIT INTO TWO PARTS OVER
THE DEEP TROPICS... ONE HIGH NEAR 18N47W WITH ANOTHER OVER W
AFRICA.  THE PRESSURE GRADIENT IS VERY WEAK OVER THE DEEP
TROPICS EXCEPT NEAR MARIA... LEAVING LIGHT WINDS AND RELATIVELY
CALM SEAS.

$$
BLAKE

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