[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 070533
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 52W S OF 21N MOVING W 10 KT. A 1009 MB
LOW IS LOCATED ALONG THE WAVE AXIS NEAR 15N. BUOY 41040 HAS BEEN
VERY HELPFUL IN ANALYZING THIS LOW...CURRENTLY REPORTING VERY
LIGHT WSW WINDS AND A PRESSURE NEAR 1010 MB. THIS LOW PRES
SYSTEM REMAINS IN AN UNFAVORABLE ATMOSPHERIC ENVIRONMENT WITH
WATER VAPOR IMAGERY AND DERIVED WINDS SHOWING STRONG SWLY FLOW
BLOWING ACROSS THE LOW. THIS SHEAR HAS STAGGERED ALL OF THE DEEP
CONVECTION...SCATTERED MODERATE IN NATURE...WITHIN 180 NM TO THE
E OF THE EXPOSED LOW-LEVEL CIRCULATION.

...THE ITCZ...
AXIS IS CENTERED ALONG 10N13W 7N28W 10N44W 11N49W 8N61W.
SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N AND 90 NM S OF
THE AXIS BETWEEN 29W-44W. SIMILAR CONVECTION IS WITHIN 90 NM
EITHER SIDE OF THE AXIS BETWEEN 20W-24W.

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 90W AS THE GRADIENT RELAXES.
SCATTERED SHOWERS AND TSTMS ARE EXPANDING SOME IN THE CENTRAL
GULF FROM 25N-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 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 PIVOT WWD SLIGHTLY.

THE CARIBBEAN SEA...
THE MAIN SYNOPTIC FEATURE IN THE REGION IS A 1005 MB LOW
CENTERED NEAR 18N84W. SFC OBSERVATIONS IN THIS VICINITY REVEAL A
BROAD LOW PRES TROUGH COVERING THE WRN HALF OF THE CARIB SEA.
THIS LOW IS NOT VERY WELL DEFINED ON NIGHT CHANNEL IMAGERY...AS
ITS TOUGH TO SEE ANY WELL DEFINED CYCLONIC TURNING IN THE CLOUD
FIELD. CONVECTION REMAINS VERY SPREAD OUT AND RATHER SPARSE WITH
SCATTERED MODERATE FROM 18N-20N W OF 86W...N OF 18N
BETWEEN 77W-80W AND FROM 15N-18N BETWEEN 70W-76W. HOWEVER...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 BROAD LOW. ELY TRADES ARE STILL FAIRLY
LIGHT...10-15 KT IN THE E CARIB DUE TO ANOTHER SFC LOW PRES
TROUGH LOCATED TO THE N OF THE REGION. LOOKING AHEAD A COUPLE OF
DAYS...THE MAIN FEATURE TO WATCH IS THE LOW PRES SYSTEM IN THE
NW CARIB AS ENVIRONMENTAL CONDITIONS APPEAR TO SUPPORT FURTHER
DEVELOPMENT.

THE ATLANTIC OCEAN...
ACTIVE WEATHER CONTINUES N OF PUERTO RICO ASSOCIATED WITH A
STRETCHED OUT SFC TROUGH...ANALYZED ALONG 26N48W 24N61W
21N73W... AND AN UPPER LOW CENTERED ABOVE THE N SHORE OF
HISPANIOLA. IR IMAGERY SHOWS GOOD ROTATION TO THE SCATTERED
MODERATE TO STRONG CONVECTION FROM 19N-23N BETWEEN 64W-67W. THIS
AREA IS BEING MONITORED FOR FURTHER DEVELOPMENT. ANOTHER BLOB OF
SIMILAR CONVECTION IS LOCATED FROM 21N-25N BETWEEN 49W-54W. THIS
CLUSTER 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 AN AREA OF 20-25 KT ELY WINDS ROUGHLY N OF 25N W OF
48W. 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 14N37W. 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 SW TO W 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 25N W OF THE CANARY ISLANDS. THE SFC PATTERN IS
RATHER TRANQUIL GOVERNED BY A 1021 MB HIGH CENTERED NEAR 27N27W.
THIS IS KEEPING WINDS LIGHT IN THE SUBTROPICS AND MODERATE IN
THE TROPICS...EXCEPT SLIGHTLY STRONGER NEAR THE AFRICAN COAST
FROM 18N-26N WHERE THE GRADIENT IS TYPICALLY TIGHT BETWEEN THE
SUBTROPICAL RIDGE AND INVERTED TROUGHING OVER THE CONTINENT.

$$
CANGIALOSI




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