[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 080528
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON OCT 08 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
0515 UTC.

...SPECIAL FEATURE...

A BROAD AREA OF LOW PRES IS CENTERED IN THE NW CARIB NEAR
18N83W...ANALYZED 1005 MB AT 03Z. THIS LOW SITS ALONG A SFC
TROUGH WHICH EXTENDS NE ACROSS THE YUCATAN PENINSULA AND INTO
THE S CENTRAL OR SW GULF. SYNOPTIC 24-HOUR TENDENCIES SHOW VERY
LITTLE TO NO DEEPENING SINCE YESTERDAY AT THIS TIME. SATELLITE
IMAGES REVEAL A BROAD SLOPPY CLOUD PATTERN WITH CONVECTION
SCATTERED ABOUT THE TROUGH AXIS...CURRENTLY WIDELY SCATTERED
MODERATE IS FROM 14N-19N BETWEEN 82W-89W. UPPER-LEVEL WINDS ARE
FAVORABLE FOR SLOW DEVELOPMENT OF THIS SYSTEM DURING THE NEXT
COUPLE OF DAYS AS IT MOVES VERY SLOWLY WESTWARD OR
NORTHWESTWARD.  AN AIR FORCE HURRICANE HUNTER AIRCRAFT IS
SCHEDULED TO INVESTIGATE THIS SYSTEM ON MONDAY...IF NECESSARY.

...TROPICAL WAVES...

TROPICAL WAVE IS ADDED TO THE 00Z ANALYSIS ALONG 37W/38W S OF
12N ESTIMATED TO BE MOVING W 15 KT. THIS LOW AMPLITUDE WAVE HAS
BEEN DIFFICULT TO SEE SINCE EMERGING OFF THE AFRICAN
COAST...LIKELY A FEW DAYS AGO...AS IT HAS BEEN EMBEDDED WITHIN
THE LINEAR ITCZ CLOUDINESS. THE WAVE IS MORE VISIBLE ON
TONIGHT'S IMAGERY WITH THE ASSOCIATED DEEP CLOUDINESS REACHING A
POLEWARD CREST ALONG THE ANALYZED AXIS. THE MIMIC TPW ANIMATION
SHOWS A NARROW RATHER QUICK WWD MOVING MOISTURE BUMP PERTURBING
THE ITCZ...RELATED TO THIS WEAK FEATURE. SCATTERED SHOWERS AND
TSTMS ARE WITHIN 210 NM EITHER SIDE OF THE AXIS.

TROPICAL WAVE IS ALONG 55W S OF 20N MOVING W TO NW NEAR 10 KT. A
1010 MB LOW IS LOCATED ALONG THE WAVE AXIS NEAR 17N. THIS LOW
ONLY CONSISTS OF LOW-LEVEL CLOUDS...AND IN FACT MAY BE OPENING
UP. WEAKENING SCATTERED MODERATE CONVECTION IS WELL REMOVED TO
THE E OF THE WAVE FROM 15N-18N BETWEEN 51W-53W...SHEARED OFF BY
STRONG UPPER SWLY FLOW.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N15W 6N24W 8N36W 9N45W 10N53W
9N62W. THE AXIS REMAINS ACTIVE TONIGHT. IN ADDITION TO THE
CONVECTION ASSOCIATED WITH THE TROPICAL WAVES...SCATTERED
MODERATE IS WITHIN 180 NM EITHER SIDE OF THE AXIS BETWEEN
25W-49W.

DISCUSSION...

THE GULF OF MEXICO...
QUITE BREEZY WEATHER CONTINUES IN THE CENTRAL AND EASTERN GULF
WATERS THIS EARLY MORNING. DATA FROM SHIPS...BUOYS AND A RECENT
QSCAT PASS REVEAL ELY WINDS MAINLY IN THE 15-20 KT RANGE E OF
ABOUT 92W. THIS MODERATE TO FRESH FLOW IS ASSOCIATED WITH A
TIGHTENED PRES PATTERN BETWEEN A BROAD LOW PRES TROUGH IN THE NW
CARIB AND A HIGH PRES RIDGE PARKED OVER THE MID-ATLANTIC STATES.
THIS MOIST FLOW IS PICKING UP STREAMS OF SHALLOW QUICK MOVING
SHOWERS FROM THE ATLC AND STEERING THEM ACROSS FLA AND THE GULF
WATERS. SLIGHTLY DEEPER MOISTURE IS IN PLACE ACROSS THE CENTRAL
GULF...ROUGHLY S OF 27N BETWEEN 85W-93W...ASSOCIATED WITH DEEP
LAYER INVERTED TROUGHING RELATED TO THE NW CARIB LOW.
CURRENTLY...IR IMAGES ARE NOT INDICATING MUCH IN THE WAY OF
ORGANIZED TSTM ACTIVITY EXCEPT FOR A QUICKLY WEAKENING PATCH
OVER THE ERN BAY OF CAMPECHE AND THE YUCATAN PENINSULA WHERE
LOW-LEVEL CONVERGENCE IS A LITTLE MORE PRONOUNCED. THE WEATHER
ACROSS THE WRN-MOST GULF REMAINS TRANQUIL...SITUATED TO THE W OF
THE INVERTED TROUGHING...WITH FAIR TO MOSTLY CLEAR SKIES AND
RATHER LIGHT SFC FLOW .

THE CARIBBEAN SEA...
THE SLOW MOVING BROAD AREA OF LOW PRES IN THE NW CARIB BETWEEN
BELIZE... HONDURAS...AND THE CAYMAN ISLANDS IS THE MAIN FEATURE
OF INTEREST TONIGHT. FOR DETAILS REFER TO THE SPECIAL FEATURE
SECTION ABOVE. ELSEWHERE...SCATTERED MODERATE CONVECTION HAS
MOVED LITTLE OVER THE PAST FEW HOURS N OF 16N BETWEEN
74W-77W...WHICH INCLUDES PORTIONS OF JAMAICA...ERN CUBA AND THE
WINDWARD PASSAGE. THIS ACTIVITY IS ASSOCIATED WITH MOIST SLY
LOW-LEVEL FLOW AND SOME CONVERGENCE IN THE LOW-LEVELS TO THE S
OF AN ATLC SFC TROUGH. UPPER-LEVEL FLOW IS ALSO DIFFLUENT OVER
THIS REGION BETWEEN TROUGHING OVER THE BAHAMAS AND RIDGING OVER
THE CENTRAL CARIBBEAN. THIS UPPER PATTERN IS HELPING TO GENERATE
AND SPREAD WIDESPREAD HIGH LEVEL CLOUDINESS ACROSS THE ENTIRE
REGION. THE SFC TRADE WIND FLOW HAS BEEN GREATLY INTERRUPTED
OVER THE PAST COUPLE OF DAYS ESP W OF 70W...DUE TO THE BROAD LOW
PRES TROUGH. THIS IS EXPECTED TO CONTINUE TO BE THE CASE FOR A
COUPLE MORE DAYS AS THE LOW MOVES VERY SLOWLY. E OF 70W...TRADES
ARE FAIRLY LIGHT BUT THEY MIGHT INCREASE SLIGHTLY BY MID-WEEK AS
THE SUBTROPICAL ATLC HIGH RIDGES FURTHER W.

THE ATLANTIC OCEAN...
AN ELONGATED SFC TROUGH PERSISTS ACROSS MUCH OF THE SW AND
CENTRAL ATLC EXTENDING FROM THE SE BAHAMAS NEWARD ALONG 22N75W
24N64W 31N49W. A WEAK LOW...ANALYZED 1011 MB...HAS FORMED ALONG
THE TROUGH AXIS NEAR 26N54W. A MID TO UPPER-LEVEL TROUGH WITH A
SERIES OF EMBEDDED SHORTWAVES ARE SUPPORTING THIS LONG STRETCHED
OUT SURFACE FEATURE. THERE ARE A COUPLE OF AREAS ALONG THE
TROUGHING WHERE LOW TO MID-LEVEL VORTICITY APPEARS TO BE
MAXIMIZED. ONE IS LOCATED SEVERAL HUNDRED MILES NORTH-NORTHWEST
OF PUERTO RICO...WHERE THERE IS A CLUSTER OF SCATTERED MODERATE
CONVECTION FROM 23N-25N BETWEEN 66W-69W. THE SECOND VORT MAX IS
TO THE E OF THE WEAK SFC LOW GENERATING SCATTERED MODERATE
CONVECTION FROM 23N-28N BETWEEN 47W-53W. UPPER-LEVEL WINDS
REMAIN STRONG WHICH ARE INHIBITING ANY TROPICAL DEVELOPMENT OF
THESE SYSTEMS. N AND W OF THE TROUGH AXIS...ELY SFC WINDS REMAIN
MODERATE TO FRESH DUE TO THE TIGHTENED GRADIENT BETWEEN THE
TROUGH AND HIGH PRES OVER THE MID ATLC STATES.

MUCH QUIETER WEATHER EXISTS E OF 40W UNDER THE INFLUENCE OF A
SFC RIDGE EXTENDING SW FROM A 1025 MB HIGH SE OF THE AZORES NEAR
35N22W. THIS IS KEEPING WINDS LIGHT IN THE SUBTROPICS AND
MODERATE IN THE TROPICS...EXCEPT SLIGHTLY STRONGER 20-25 KT NLY
WINDS OFF THE COAST OF NW AFRICA WHERE THE GRADIENT REMAINS
TIGHTER PER USUAL. THE MAIN MID TO UPPER LEVEL FEATURE OVER THE
TROPICS IS AN UPPER HIGH LOCATED NEAR 12N39W. THE UPPER-LEVEL
FLOW IS QUITE STRONG OUT OF THE W TO SW ON THE NORTHERN SIDE OF
THE TROPICAL RIDGE WHICH IS SPREADING SOME HIGH DEBRIS
CLOUDINESS...FROM ITCZ CONVECTION...S OF 20N BETWEEN 32W-47W. A
SHARP UPPER TROUGH IS BEGINNING TO CUT OFF JUST TO THE NE
OF THE MADEIRA ISLANDS. THIS FEATURE IS GENERATING SOME
CLOUDINESS AND SHOWERS OVER THOSE ISLANDS AND NE TOWARD SRN
PORTUGAL WITH A TAIL OF MOISTURE PASSING THROUGH THE CANARY
ISLANDS.

$$
CANGIALOSI






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