[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 240605
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON SEP 24 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0530 UTC.

...SPECIAL FEATURE...
TROPICAL STORM JERRY AT 24/0300 UTC WAS CENTERED NEAR 37.4N
46.1W OR ABOUT 910 NM W OF THE AZORES...MOVING N AT 7 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB.  MAXIMUM
SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.  SEE LATEST
NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/WTNT21
FOR MORE DETAILS. JERRY IS A SHEARED TROPICAL CYCLONE WITH
LIMITED DEEP CONVECTION. THE STORM IS EXPECTED TO ACCELERATE TO
THE NE SOON...AND EVENTUALLY GET ABSORBED INTO THE LARGE
EXTRATROPICAL CYCLONE MOVING OFF THE CANADIAN MARITIMES IN ABOUT
24-36 HOURS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE
NEXT 24 HOURS.

A WELL DEFINED TROPICAL WAVE IS LOCATED ALONG 57W OR ABOUT 175
NM E OF THE SOUTHERN WINDWARD ISLANDS. THE WAVE IS REPRESENTED
WELL BY THE SURROUNDING SURFACE OBSERVATIONS...AND A QUIKSCAT
PASS FROM 23/2200 UTC. THIS WAVE IS GENERATING SCATTERED SHOWER
AND TSTM ACTIVITY FROM 9N-15N BETWEEN 53W-62W. THIS ACTIVITY
WILL SPREAD THROUGH THE WINDWARD ISLANDS THROUGH MONDAY BRINGING
SQUALLY WEATHER TO THE AREA...AND POSSIBLY TO THE LEEWARD
ISLANDS BY TUESDAY. THIS SYSTEM HAS CHANGED LITTLE IN
ORGANIZATION OVER THE PAST DAY...BUT HAS THE POTENTIAL TO
DEVELOP INTO A TROPICAL DEPRESSION DURING THE NEXT DAY OR SO.
INTERESTS IN THE LESSER ANTILLES SHOULD MONITOR THE PROGRESS OF
THIS SYSTEM.

A 1007 MB LOW PRESSURE SYSTEM IS LOCATED ABOUT 565 NM SSW OF THE
CAPE VERDE ISLANDS NEAR 8N31W. THIS LARGE SYSTEM CONTINUES TO
SHOW SIGNS OF ORGANIZATION...AND COULD BECOME A TROPICAL
DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES
WEST-NORTHWESTWARD AT ABOUT 10-15 KT. THE MOST CONCENTRATED AREA
OF SCATTERED MODERATE CONVECTION IS S OF THE CENTER FROM 5N-8N
BETWEEN 28W-35W. ISOLATED CLUSTERS OF MODERATE CONVECTION ARE
ELSEWHERE FROM 4N-15N BETWEEN 26W-36W. THIS IS ONE OF THE MORE
CLASSIC LOOKING CAPE VERDE SYSTEMS WE HAVE SEEN OVER THE PAST
COUPLE OF WEEKS.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 37W S OF 18N MOVING W 10-15 KT. THIS WAVE
HAS MAINTAINED GOOD WWD CONTINUITY IN BOTH SATELLITE HOVMOLLER
DIAGRAMS AND THE MIMIC TPW ANIMATION SINCE EMERGING OFF THE
COAST OF AFRICA A FEW DAYS AGO.  HOWEVER...THE LARGE LOW
PRESSURE SYSTEM E OF THE WAVE...ERN MOST SPECIAL FEATURE
DISCUSSED ABOVE...CONTINUES TO OVERTAKE THIS WAVE AND IS BY FAR
THE DOMINANT FEATURE IN THE AREA. MOST OF THE REMAINING
SHOWER/TSTM ACTIVITY ASSOCIATED WITH THE WAVE IS SCATTERED FROM
11N-13N BETWEEN 36W-40W.

TROPICAL WAVE IS IN THE W CARIBBEAN ALONG 83W/84W S OF 19N
MOVING W 10-15 KT.  THE WAVE IS NOT EASILY SEEN IN ANY OF THE
AVAILABLE DATA AND CONTINUES TO FOLLOW CONTINUITY FROM PREVIOUS
ANALYSES. SHOWER ACTIVITY IN THE VICINITY IS CURRENTLY MINIMAL.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N15W 8N28W 6N40W 11N56W 10N62W.
BESIDES THE ACTIVITY ASSOCIATED WITH THE SPECIAL FEATURES AND
TROPICAL WAVE... SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS ALONG AND JUST OFFSHORE THE COAST OF AFRICA FROM
12N-15N BETWEEN 15W-18W. SIMILAR ACTIVITY IS FURTHER S FROM
4N-10N BETWEEN 11W-16W...AND NEAR 6N19W. THIS ACTIVITY MAY BE
ASSOCIATED WITH THE NEXT TROPICAL WAVE.

DISCUSSION...

GULF OF MEXICO...
ABUNDANT DEEP LAYER MOISTURE AND DISORGANIZED SHOWER ACTIVITY
ARE OVER THE GULF WATERS E OF 92W. THE MOST CONCENTRATED
SHOWER/TSTM ACTIVITY IS JUST OFF THE YUCATAN PENINSULA FROM
21N-23N BETWEEN 89W-92W...AND ALSO A COUPLE HUNDRED MILES
OFFSHORE FLORIDA FROM 25N-28N BETWEEN 84W-87W. THE CLUSTER
OFFSHORE THE YUCATAN IS MOSTLY CLOSELY ASSOCIATED TO THE BROAD
SURFACE TROUGH IN THE VICINITY...AND RECENT SHORTWAVE IR IMAGERY
SUGGESTS A WEAK LOW MAY BE NEAR 21N91W. AS OF 24/0300 UTC THE
SFC TROUGH WAS ANALYZED OVER THE WEST/CENTRAL GULF GENERALLY
ALONG 91W S OF 27N. THE UPPER SUPPORT FOR THE MOISTURE E OF 92W
CONSISTS OF DIFFLUENT FLOW BETWEEN AN UPPER TROUGH EXTENDING S
THROUGH TEXAS AND NE MEXICO...AND UPPER RIDGING OVER THE ERN
GULF. DEEP MOISTURE WITH SCATTERED SHOWER/TSTM ACTIVITY TO
PERSIST ESPECIALLY BETWEEN 84W-96W...BETWEEN THE YUCATAN AND
LOUISIANA...OVER THE NEXT DAY OR SO.

CARIBBEAN SEA...
NO ORGANIZED DEEP CONVECTION IS AFFECTING THE BASIN TONIGHT.
MUCH OF THE MOISTURE/SHOWER ACTIVITY THAT WAS IN THE NW
CARIBBEAN RECENTLY HAS PUSHED NW OF THE AREA WITH THE ASSOCIATED
TROUGH/WEAK SFC LOW NOW OVER THE GULF. HOWEVER...THERE DOES
APPEAR TO BE SOME LINGERING SHOWER ACTIVITY W OF 86W. THE TAIL
END OF THE LONG SFC TROUGH IN THE ATLC APPEARS TO BE GENERATING
ISOLATED SHOWERS/TSTMS IN THE NE CARIBBEAN N OF 14N E OF 67W.
SHOWER ACTIVITY WILL INCREASE IN THE ERN PORTION OVER THE NEXT
COUPLE OF DAYS WITH THE WELL DEFINED TROPICAL WAVE
APPROACHING...SEE SPECIAL FEATURE SECTION ABOVE FOR DETAILS.
TRADES ARE MOSTLY LIGHT EXCEPT MODERATE VELOCITIES STILL NOTED
PER USUAL OVER THE CENTRAL PORTION FROM 11N-16N BETWEEN 67W-78W.
THE UPPER PATTERN CONSISTS OF A FAIRLY WELL DEFINED
RIDGE/TROUGH/RIDGE PATTERN.

ATLANTIC OCEAN...
MOST OF THE ACTIVE SFC FEATURES ARE DISCUSSED IN THE SPECIAL
FEATURES SECTION ABOVE. ELSEWHERE AT THE SFC...WEAK HIGH PRES
RIDGING CONTROLS THE W ATLC. TROUGHING DOMINATES MUCH OF THE
CENTRAL ATLC ZONE TO THE S OF TROPICAL STORM JERRY. THE
ELONGATED TROUGH AXIS ENTERS THE AREA NEAR 31N45W AND CONTINUES
SW THROUGH 24N55W 21N61W 17N63W. THE MOST PRONOUNCED LOW LEVEL
CYCLONIC TURNING IS NOTED NEAR 22N60W...AND IS ACCOMPANIED BY A
CLUSTER OF MODERATE CONVECTION FROM 21N-25N BETWEEN 57W-61W.
WILL WAIT FOR VISIBLE IMAGERY TO PUT A LOW IN THIS VICINITY.
ISOLATED SHOWER/TSTM ARE ELSEWHERE WITHIN 250 NM OF THE TROUGH.
MODERATE RIDGING TAKES OVER IN THE E ATLC ANCHORED BY A 1025 MB
CENTERED TO THE E OF THE AZORES NEAR 39N23W. THIS OVERALL
PATTERN IS PRODUCING MODERATE TRADES IN THE E ATLC...EXCEPT
STRONGER NEAR THE TYPICAL TIGHTENED GRADIENT NEAR THE COAST OF
NW AFRICA. LIGHT TO MODERATE WINDS EXIST ELSEWHERE IN THE FAIRLY
RELAXED GRADIENT. THE OTHER SFC FEATURE IS IN THE TROPICAL
ATLC...WITH A 1012MB LOW NEAR 14N46W. THIS IS GENERATING
SCATTERED MODERATE CONVECTION FROM 13N-16N BETWEEN 45W-48W.

IN THE MID AND UPPER LEVELS...N/NW FLOW AROUND THE SE GULF HIGH
IS ADVECTING MID-HIGH CLOUDINESS AND ISOLATED SHOWERS S/SE W OF
70W. THE FLOW FROM THE E GULF RIDGING FOLDS INTO A VERY
BROAD TROUGH COVERING THE AREA BETWEEN 43W-75W....WITH A FEW
EMBEDDED SHORTWAVES NOTED. THE OVERALL BROAD TROUGH IS
PROVIDING SOME SUPPORT FOR THE WEAK LOW-LEVEL BOUNDARY IN THE
CENTRAL ATLC DISCUSSED ABOVE. AN AMPLIFIED UPPER RIDGE TAKES
OVER E OF THE TROUGH WITH THE AXIS EXTENDING ROUGHLY N-S ALONG
37W. A LARGE UPPER LOW IS SITUATED E OF THE RIDGE W OF THE
MADEIRA ISLANDS NEAR 33N20W. THIS LOW IS PROVIDING PRONOUNCED
TROUGHING ACROSS THE NEARLY THE ENTIRE ATLC E OF 30W. SWLY FLOW
ON THE E SIDE OF THE LOW IS GENERATING SCATTERED CLOUDINESS OVER
AND TO THE W OF THE CANARY ISLANDS.

$$
MW




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