[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071044
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN OCT 07 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1030 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 52W/53W S OF 18N MOVING W 10 KT. A 1008
MB LOW IS LOCATED ALONG THE WAVE AXIS NEAR 16N. BUOY 41040 HAS
BEEN VERY HELPFUL IN ANALYZING THIS LOW. IR IMAGERY SHOWS A BALL
OF CONVECTION THAT HAS BEEN MAINTAINED THROUGHOUT THE OVERNIGHT
HOURS. HOWEVER...ALL OF THIS CONVECTION IS SITUATED TO THE E/SE
OF AN EXPOSED LOW-LEVEL CIRCULATION CENTER. THIS LOW PRES SYSTEM
IS OBVIOUSLY FEELING THE EFFECTS OF WLY SHEAR WHICH IS HAMPERING
FURTHER ORGANIZATION.

...THE ITCZ...
AXIS IS CENTERED ALONG 12N16W 8N24W 9N40W 10N51W 9N62W. THE ITCZ
HAS BECOME MUCH MORE ACTIVE THIS MORNING WITH SCATTERED MODERATE
CONVECTION WITHIN 90 NM N AND 120 NM S OF THE AXIS BETWEEN
23W-45W. A CLUSTER OF SCATTERED MODERATE IS NEAR THE COAST OF
AFRICA FROM 7N-9N E OF 15W.

DISCUSSION...

THE GULF OF MEXICO...
THE SFC FLOW IS ON THE BRISK SIDE IN THE E GULF IN RESPONSE TO A
TIGHTENED PRES PATTERN BETWEEN LOW PRES TO THE S IN THE NW
CARIBBEAN AND HIGH PRES OVER AND OFF THE MID-ATLANTIC COASTLINE.
THIS STIFF FLOW IS BLOWING ISOLATED STREAMS OF SHOWERS FROM THE
ATLC ACROSS FLORIDA AND INTO THE E GULF WATERS. THE SFC FLOW
SIGNIFICANTLY SLACKENS W OF 92W AS THE GRADIENT RELAXES.
SCATTERED SHOWERS AND TSTMS ARE EXPANDING SOME IN THE CENTRAL
GULF FROM 24N-29N BETWEEN 88W-92W. THIS ACTIVITY IS ASSOCIATED
WITH DEEP LAYER INVERTED TROUGHING WHICH EXTENDS NWD FROM THE
AFOREMENTIONED LOW IN THE NW CARIB. SKY CONDITIONS ACROSS MOST
OF THE W GULF ARE FAIR TO MOSTLY CLEAR UNDER A MODERATE
SUBSIDENT ENVIRONMENT SUPPORTED BY A SOMEWHAT CONFLUENT UPPER
PATTERN. LOOKING AHEAD A DAY OR SO...WINDS ARE EXPECTED TO
REMAIN MODERATE TO FRESH IN THE E GULF AND THE MOISTURE PLUME IS
ANTICIPATED TO CONTINUE PIVOTING WWD.

THE CARIBBEAN SEA...
THE MAIN AREA OF FOCUS CONTINUES TO BE THE BROAD LOW PRES TROUGH
OBSERVED ACROSS THE WRN HALF OF THE CARIB SEA. YESTERDAY AND
EARLIER THIS MORNING...INCLUDING ON THE 06Z ANALYSIS...WE HAVE
BEEN TRACKING A BROAD AREA OF LOW PRES IN THE NW CARIB. BASED ON
THE LATEST SATELLITE IMAGERY AND SFC DATA THERE APPEARS TO BE
TWO LOWS EMBEDDED IN THE TROUGH. AS OF 09Z...THE NRN LOW IS
ANALYZED ABOUT 75 NM SE OF COZUMEL MEXICO NEAR 20N86W. THE SRN
LOW IS LOCATED ABOUT 150 NM NE OF ERN HONDURAS NEAR
17N82W...BOTH OF THESE ARE ESTIMATED TO BE 1004 MB. SYNOPTIC SFC
PRESSURES ARE RUNNING 2-4 MB LOWER ACROSS THIS GENERAL VICINITY
COMPARED TO THIS TIME YESTERDAY. THE LOW OF INTEREST THIS
MORNING IS THE SRN ONE AS CONVECTION HAS FORMED AND EXPANDED
SINCE COMING OUT OF THE GOES-E SAT ECLIPSE A FEW HOURS AGO.
CURRENTLY...SCATTERED MODERATE IS WITHIN 150 NM S SEMICIRCLE.
THIS AREA IS BEING MONITORED AS ENVIRONMENTAL CONDITIONS APPEAR
TO SUPPORT FURTHER DEVELOPMENT.

ELSEWHERE...WIDELY SCATTERED MODERATE CONVECTION IS BETWEEN
69W-77W. A GLANCE AT WATER VAPOR IMAGERY SUGGESTS THAT MUCH OF
THIS IS SUPPORTED BY MID-UPPER LEVEL FEATURES. THE PATTERN
CONSISTS OF BROAD INVERTED TROUGHING W OF 75W AND WLY FLOW E OF
75W ON THE S SIDE OF AN UPPER LOW CENTERED JUST N OF HISPANIOLA.
WIDESPREAD MID TO HIGH LEVEL CLOUDINESS COVERS THE BULK OF THE
AREA. THE TYPICAL TRADE WIND FLOW IS INTERRUPTED IN THE WRN
CARIB DUE TO THE PRESENCE OF THE LOW PRES TROUGH. ELY TRADES ARE
STILL FAIRLY LIGHT...10-15 KT IN THE E CARIB...DUE TO ANOTHER
SFC TROUGH LOCATED TO THE N OF THE REGION.

THE ATLANTIC OCEAN...
ACTIVE WEATHER CONTINUES N OF PUERTO RICO ASSOCIATED WITH A
STRETCHED OUT SFC TROUGH...ANALYZED ALONG 27N50W 23N60W TO THE
ERN BAHAMAS NEAR 22N73W...AND AN UPPER LOW CENTERED ABOVE THE N
SHORE OF HISPANIOLA. IR IMAGERY CONTINUES TO SHOW SOME ROTATION
TO THE MID-LEVEL CLOUDINESS...ALTHOUGH CONVECTION HAS DECREASED
SINCE EARLIER THIS MORNING. CURRENTLY...SCATTERED MODERATE IS
FROM 19N-23N BETWEEN 64W-68W. THIS AREA IS BEING MONITORED FOR
FURTHER DEVELOPMENT. ANOTHER BLOB OF SIMILAR CONVECTION IS
LOCATED FROM 21N-27N BETWEEN 48W-53W. THIS LARGE PATCH OF
ACTIVITY IS BEING ENHANCED BY THE SAME SFC TROUGH COUPLED WITH
DIFFLUENCE ALOFT ON THE E SIDE OF A SHORTWAVE MID TO UPPER
TROUGH. THE TIGHTENED PRES GRADIENT BETWEEN THIS FAIRLY
HORIZONTAL SFC TROUGH AND A HIGH PRES RIDGE N OF BERMUDA IS
GENERATING A RATHER LARGE AREA OF 20-25 KT ELY WINDS ROUGHLY N
OF 24N W OF 55W. SCATTERED QUICK MOVING SHOWERS ARE POSSIBLE
JUST ABOUT ANYWHERE UNDER THIS STRONG LOW-LEVEL FLOW REGIME.

MUCH QUIETER WEATHER EXISTS E OF 45W. THE MAIN MID TO UPPER
LEVEL FEATURE IS A HIGH PRES AREA CENTERED NEAR 12N38W. THIS
SYSTEM IS HELPING TO SINK THE AIR ACROSS MOST OF THE TROPICS
KEEPING CONVECTION CONFINED TO THE ITCZ. IN THE SUBTROPICS...THE
UPPER FLOW IS QUITE STRONG OUT OF THE W TO SW ON THE N SIDE OF
THE TROPICAL RIDGE AND ENHANCED E OF A TROUGH WHICH EXTENDS TO
27N28W. THIS SWIFT FLOW IS SPREADING DEBRIS MOISTURE ACROSS MUCH
OF THE AREA N OF 23N W OF THE CANARY ISLANDS. THE SFC PATTERN IS
RATHER TRANQUIL GOVERNED BY A 1020 MB HIGH CENTERED NEAR 28N33W.
THIS IS KEEPING WINDS LIGHT IN THE SUBTROPICS AND MODERATE IN
THE TROPICS...EXCEPT SLIGHTLY STRONGER 20-25 KT NLY WINDS
BETWEEN THE CAPE VERDE ISLANDS AND THE AFRICAN COAST FROM
17N-23N WHERE THE GRADIENT IS TYPICALLY TIGHT BETWEEN THE
SUBTROPICAL RIDGE AND INVERTED TROUGHING OVER THE CONTINENT.

$$
CANGIALOSI




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