[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 190003
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT WED OCT 18 2006


TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
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...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 2345 UTC.

...TROPICAL WAVE...
AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ADDED ALONG 32W S OF
19N ESTIMATED TO BE MOVING W 5 TO 10 KT. THIS IS SLIGHTLY W OF
WHAT SEEMS TO BE MORE OF A MID LEVEL CIRCULATION CENTERED AROUND
14N30W. I WAS RELUCTANT TO PUT THIS FEATURE ON THE MAP LAST
EVENING AS THE METEOSAT 8 HOVMOLLER DIAGRAM SHOWED LITTLE
WESTWARD MOTION. HOWEVER...TODAYS HOVMOLLER ANALYSIS SHOWS IT
HAS BEGUN TO MOVE SLOWLY TO THE W. THE EXACT AXIS LOCATION IS A
LITTLE UNCLEAR BUT ENOUGH TURNING OF THE LOW CLOUD FIELD EXISTS
TO WARRANT A WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS FROM 11N-18N BETWEEN 30W-35W...AND FROM 9N-13N BETWEEN
26N-31W. SW SHEAR ESPECIALLY OVER THE NORTHERN PORTION OF THE
WAVE CONTINUES TO STRETCH THE ASSOCIATED HIGH CLOUDS TO THE NE.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 42W SOUTH OF 21N MOVING
WEST AT 15 KT. CYCLONIC TURNING/INVERTED V REMAINS EVIDENT IN
THE LOW CLOUD FIELD. DEEP CONVECTION REMAINS MINIMAL WITH
ISOLATED SHOWERS/TSTMS NOTED WITHIN 150NM OF THE AXIS FROM
10N-15N.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N13W 10N30W 10N40W 8N50W 7N60W.
OUTSIDE OF THE CONVECTION ASSOCIATED WITH THE TROPICAL
WAVES...NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS OVER WRN
AFRICA AND THE ADJACENT ERN ATLC WATERS FROM 8N-12N BETWEEN
11W-16W. A SMALL CLUSTER OF MODERATE CONVECTION NOTED NEAR
8N23W. SCATTERED MODERATE CONVECTION FROM 4N-9N BETWEEN 37W-40W.
OTHER CLUSTERS OF MODERATE CONVECTION ARE MOVING NE FROM S
AMERICA INTO THE ATLC FROM 4N-7N BETWEEN 51W-58W.

...DISCUSSION...
GULF OF MEXICO...
LINE OF SHOWERS/TSTMS THAT IS HUGGING FLORIDA PANHANDLE...NRN
GULF...AND BIG BEND AREA HAS BEEN LOSING ITS IDENTITY OVER THE
LAST 24 HRS. THE OPPOSITE CAN BE SAID FOR THE CONVECTION OVER
ERN TEXAS AND LOUISIANA ASSOCIATED WITH THE UNSTABLE ENVIRONMENT
S OF A STATIONARY FRONT...THOUGH THIS IS NOT EFFECTING THE GULF.
A PRONOUNCED UPPER HIGH CONTINUES TO DOMINATE THE GULF THIS
EVENING...WITH AN ESTIMATED CENTER NEAR 26N91W. THIS ALONG WITH
FAIRLY DRY MID TO UPPER LEVEL AIR IS HELPING TO PRODUCE ABUNDANT
FAIR WEATHER ACROSS THE GULF ASIDE FROM THE DIMINISHING LINE OF
SHOWERS IN THE NE PORTION. GENTLE 5 TO 10KT ANTICYCLONIC FLOW
FOUND AT THE SURFACE IN THE ERN GULF AROUND THE SW PORTION OF AN
ATLC RIDGE. 10 TO 15 KT SE FLOW IN THE WRN PORTION AS THIS HIGH
INTERACTS WITH LOWER PRESSURE OVER MEXICO. COLD FRONT EXPECTED
TO ENTER THE NW GULF TOMORROW WITH N/NE FLOW INCREASING OFF THE
TEXAS COAST INTO TOMORROW EVENING...SEE MIAOFFNT4 FOR DETAILS.

CARIBBEAN SEA...
NE/ENE FLOW AROUND THE UPPER HIGH OVER THE GULF DOMINATES THE
GULF W OF 70W THIS EVENING...ACCOMPANIED BY DRY MID TO UPPER AIR
AND LOTS OF FAIR WEATHER. THE SURFACE PATTERN IN THIS VICINITY
IS A BIT MORE COMPLEX. THERE ARE NUMEROUS LOW LEVEL VORTICITY
MAXIMUMS SEEN IN THE CENTRAL CARIBBEAN FROM 10N-18N BETWEEN
70W-83W. INSTEAD OF SPLATTERING THE 1800 UTC MAP WITH TONS OF
SURFACE LOWS HAVE OPTED TO WAIT FOR MORE CONFIRMATION FROM THE
AVAILABLE BUOY AND SHIP OBSERVATIONS. NONETHELESS SOME
ADJUSTMENTS WILL LIKELY BE NEEDED FOR THE 0000 UTC MAP. MOST OF
THESE LOW LEVEL CENTERS SEEM TO BE ORIENTED ALONG SOME SORT OF
BOUNDARY ON THE EDGE OF A REBUILDING ATLC RIDGE FROM THE NE. IN
THE ERN CARIBBEAN...A SURFACE TROUGH EXTENDS SSW TO THE ABC
ISLANDS FROM A 1006MB SURFACE LOW ABOUT 100NM N OF RINCON PUERTO
RICO. MOST OF THE ASSOCIATED CONVECTION IS CONFINED TO PUERTO
RICO...THE VIRGIN ISLANDS...AND THE ATLC WATERS TO THE N. UPPER
WESTERLY FLOW IS OVER THIS AREA S OF AN UPPER LOW NE OF THE
LEEWARD ISLANDS.

ATLANTIC OCEAN...
NORTHERLY UPPER FLOW DOMINATES THE WRN ATLC W OF 65W AROUND THE
PRONOUNCED UPPER HIGH FROM THE GULF. THIS REGION ALSO DOMINATED
BY LOW LEVEL ANTICYCLONIC FLOW AROUND THE SW PORTION OF A 1020
MB SURFACE HIGH JUST S OF NEWFOUNDLAND. LOW LEVEL CONFLUENCE
BETWEEN THIS HIGH AND THE 1017MB CENTRAL ATLC SFC HIGH NEAR
27N39W IS HELPING TO SUPPORT THE TROUGH EXTENDING NE FROM THE
SURFACE LOW N OF PUERTO RICO ALONG 21N67W 30N51W. THERE IS ALSO
AN UPPER LOW IN THIS VICINITY NEAR 25N58W. THE MOST SIGNIFICANT
CONVECTION ASSOCIATED WITH THESE FEATURES IS THE NUMEROUS
MODERATE/ISOLATED STRONG ACTIVITY E OF THE SURFACE LOW N OF
PUERTO RICO...FROM 17N-23N BETWEEN 62W-67W. SCATTERED SHOWERS
AND TSTMS ALSO SEEN SPINNING AROUND THE UPPER LOW FROM 16N-29N
BETWEEN 50W-58W. STRONG UPPER WLY FLOW IS OVER THE TROPICAL
NORTH ATLC WATERS E OF THE WINDWARD ISLANDS S OF THE UPPER LOW
AND N OF A UPPER HIGH OVER S AMERICA. THERE IS A SHORT WAVE
UPPER RIDGE ALONG 46W THEN A SHORTWAVE TROUGH JUST TO ITS E IN
THE MIDST OF DRY AIR. ANOTHER UPPER HIGH NOTED NEAR 30N32W. THE
FAR ERN ATLC DOMINATED BY A TROF EXTENDING SW FROM THE DEEP
LAYER LOW N OF NW SPAIN THAT HAS A WEAK SURFACE REFLECTION ALONG
30N18W 28N34W...THAT HAS A DRY 1014 SFC LOW IN THE MIDDLE OF
THOSE POINTS NEAR 29N24W. S OF THIS TROUGHING...UPPER RIDGING
CONTINUES TO EXTEND W FROM AFRICA. OVERALL SIMILAR CONDITIONS
EXPECTED THROUGH 24HRS WITH THE LOW N OF PUERTO RICO DRIFTING TO
THE WNW. GFS SUGGESTS THIS LOW WILL DEEPEN SLIGHTLY BUT TROPICAL
CYCLONE FORMATION IS NOT EXPECTED.

$$
WILLIS


This weather bulletin was brought to you by:
www.nashvilleweather.net