[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 230451
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT SEP 23 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0315 UTC.

...SPECIAL FEATURES...
HURRICANE HELENE WAS DOWNGRADED TO TROPICAL STORM AT 23/0300
UTC. TROPICAL STORM HELENE IS CENTERED NEAR 36.0N 50.6W OR ABOUT
1135 NM WEST OF THE AZORES AT 23/0300 UTC MOVING EAST-NORTHEAST
AT 20 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB. MAXIMUM
SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. SEE THE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/
WTNT23 KNHC FOR MORE DETAILS. SATELLITE REPRESENTATION APPEARS
THAT HELENE IS BECOMING LESS TROPICAL IN NATURE AND IS EXPECTED
TO BECOME EXTRATROPICAL IN THE NEXT 12 TO 24 HOURS. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS REMOVED FROM THE CENTER
TOWARD THE NW WITHIN 75 NM OF LINE 37N54W-41N49W. DENSE OVERCAST
CLOUDS WITH SHOWERS/THUNDERSTORMS COVERS A LARGER AREA FROM
33N-44N BETWEEN 45W-56W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 40W S OF 20N WITH A 1010 MB LOW ALONG THE
WAVE NEAR 13N MOVING W 5-10 KT. BROAD LOW/MID LEVEL CYCLONIC
ROTATION COVERING A LARGE AREA WITH SCATTERED MODERATE/STRONG
CONVECTION WITHIN 90/120 NM OF LINE 13N42W-17N37W-21N41W.

TROPICAL WAVE IS ALONG 55W S OF 19N WITH A 1012 MB LOW ALONG THE
WAVE NEAR 13N MOVING W 10-15 KT. BROAD CYCLONIC ROTATION COVERS
THE AREA FROM 12N-18N BETWEEN 52W-58W WITH ISOLATED SHOWERS
WITHIN 45 NM OF LINE 11N52W-14N56W.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N13W 8N22W 13N38W 11N46W 12N53W
10N62W ACROSS N PORTION OF SOUTH AMERICA THEN S OF PANAMA INTO
THE E PACIFIC REGION. APART FROM THE CONVECTION ASSOCIATED WITH
THE TROPICAL WAVES...CLUSTERS OF SCATTERED MODERATE CONVECTION
ARE FROM 4N-12BETWEEN 20W-36W AND FROM 8N-14N BETWEEN 40W-50W.

...DISCUSSION...
GULF OF MEXICO...
VERY LARGE UPPER LOW IS SITUATED OVER THE N/CENTRAL PLAIN STATES
WITH AN UPPER TROUGH EXTENDING S ACROSS TEXAS AND THE NW GULF
COAST. THIS CONTINUES TO BRING DRY AIR TO THE AREA INCLUDING THE
SE US S OF THE MAJOR THUNDERSTORMS MOVING ACROSS THE UPPER
MISSISSIPPI VALLEY. AN UPPER LOW MOVING N INTO THE SE GULF JUST
N OF THE YUCATAN PENINSULA/CHANNEL NEAR 23N86W COVERS THE E GULF
S OF 28N E OF 90W GENERATING SCATTERED SHOWERS S OF 24N FROM
84W-88W. THE RETURN SURFACE FLOW COVERS MUCH OF THE GULF TONIGHT
GENERATING ISOLATED SHOWERS N OF 28N TO INLAND OVER SE US
BETWEEN THE W COAST OF FLORIDA THROUGH THE PANHANDLE TO
LOUISIANA.

CARIBBEAN SEA...
THE UPPER LOW CENTERED IN THE SE GULF COVERS THE AREA FROM THE
GULF OF HONDURAS W OF THE CAYMAN ISLANDS OVER THE YUCATAN
PENINSULA/CHANNEL AND W CUBA GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS WITHIN 75 NM OF LINE FROM THE COAST OF
HONDURAS NEAR 16N85W TO OVER W CUBA NEAR 22N84W. BROAD UPPER
RIDGE OVER THE W ATLC IS GIVING THE REMAINDER OF THE CARIBBEAN
NE UPPER FLOW WITH MOSTLY DRY AIR. LATE AFTERNOON THUNDERSTORMS
THAT DEVELOPED OVER HISPANIOLA AND CUBA HAVE DRIFTED INTO THE N
CARIBBEAN AND ARE BEGINNING TO DISSIPATE. THE REMAINDER OF THE
CARIBBEAN REMAINS VERY DRY TONIGHT.

ATLANTIC OCEAN...
BROAD UPPER RIDGE COVERS THE W ATLC ANCHORED BY AN UPPER HIGH
OFF THE FLORIDA COAST NEAR 29N77W AND COVERING THE AREA W OF 60W
INCLUDING PORTIONS OF THE CARIBBEAN. UPPER HIGH ASSOCIATED WITH
HURRICANE HELENE IS WELL N OF THE REGION. NARROW UPPER TROUGH
EXTENDS FROM AN UPPER LOW N OF THE REGION NEAR 33N39W SSW INTO
THE W TROPICAL ATLC NEAR 16N53W. BROAD UPPER HIGH ANCHORED JUST
NW OF THE CAPE VERDE ISLANDS NEAR 18N27W COVERS THE REMAINDER OF
THE E ATLC. AT THE SURFACE...A WEAK SURFACE TROUGH IS IN THE
CENTRAL ATLC FROM 31N54W SSW TO 24N60W IN THE WAKE OF TROPICAL
STORM HELENE SPLITTING THE SUBTROPICAL RIDGE THAT DOMINATES THE
MUCH OF THE ATLC. W ATLC SURFACE RIDGE COVERS THE REGION N OF
20N FROM 60W-85W ANCHORED BY A 1024 MB HIGH WELL N OF THE REGION
AND THE E ATLC RIDGE COVERS THE REGION N OF 22N FROM 20W-50W
ANCHORED BY A 1023 MB HIGH EQUALLY AS FAR N. THIS IS GIVING MOST
OF THE ATLC FAIR WEATHER TONIGHT EXCEPT WITHIN 200 NM OF THE
SURFACE TROUGH WHERE ISOLATED SHOWERS ARE POSSIBLE.

$$
WALLACE




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