[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 220522
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT FRI SEP 22 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 IS CENTERED NEAR 31.8N 56.3W OR ABOUT 434 MILES
EAST OF BERMUDA AT 22/0300 UTC MOVING NORTH-NORTHEAST AT 12 KT.
ESTIMATED MINIMUM CENTRAL PRESSURE IS 970 MB. MAXIMUM SUSTAINED
WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SEE THE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. BROAD UPPER TROUGH IS QUICKLY APPROACHING
HELENE WITH MUCH DRIER AIR AND WILL BEGIN PUSHING THE SYSTEM NNE
AND NE IN 48 HOURS. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVERS THE AREA FROM 30N-34N BETWEEN 55W-58W. DENSE
OVERCAST CLOUDS WITH SHOWERS/THUNDERSTORMS COVERS A MUCH LARGER
AREA FROM 26N-37N BETWEEN 52W-59W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 37W S OF 19N WITH A 1010 MB LOW ALONG THE
WAVE NEAR 12N MOVING W 15 KT. BROAD MID LEVEL CYCLONIC ROTATION
COVERING A LARGE AREA WITH CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION FROM 8N-19N BETWEEN 30W-42W.

TROPICAL WAVE IS ALONG 49W/50W S OF 19N WITH A 1010 MB LOW ALONG
THE WAVE NEAR 12N. THIS EQUATES THAT THE WAVE HAS MOVED VERY
LITTLE OVER THE PAST 24 HOURS. HOWEVER...THE LOW LEVEL CENTER
APPEARS TO BE MOVING W AT 5 TO 10 KT OVER THE PAST 6 HOURS.
BROAD CYCLONIC ROTATION COVERS THE AREA FROM 10N-18N BETWEEN
47W-55W WITH ISOLATED THUNDERSTORMS NEAR THE LOW LEVEL CENTER.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N13W 12N34W 10N41W 12N48W ACROSS N
PORTION OF SOUTH AMERICA NEAR 9N61W THEN S PANAMA INTO THE E
PACIFIC REGION. APART FROM THE CONVECTION ASSOCIATED WITH THE
TROPICAL WAVE ALONG 37W...CLUSTERS OF SCATTERED MODERATE/
ISOLATED STRONG CONVECTION ARE WITHIN 120 NM ALONG THE COAST OF
AFRICA FROM 7N-10N.

...DISCUSSION...
GULF OF MEXICO...
VERY LARGE UPPER LOW IS MOVING THROUGH THE N/CENTRAL PLAIN
STATES WITH AN UPPER TROUGH MOVING ACROSS TEXAS TO ALONG THE NW
GULF COAST. THIS IS BRINGING DRY AIR TO THE TEXAS COAST AND WILL
BE IN THE GULF IN THE NEXT FEW HOURS. THIS IS ALSO FORCING THE
FRONTAL BOUNDARY THAT HAS BEEN IN THE GULF OF MEXICO OVER THE
LAST 24 HOURS TO BY PUSHED NE AS A WARM FRONT EXTENDING FROM
OVER LOUISIANA INTO THE GULF NEAR 29N90W TO THE DISSIPATING
FRONT NEAR 26N85W. AN UPPER LOW IN THE NW CARIBBEAN IS OVER THE
SE GULF S OF 26N E OF 90W. THE BROAD UPPER RIDGE ANCHORED ALONG
THE W COAST OF MEXICO IS BEING NARROWED BY THESE UPPER TROUGHS
EXTENDING A RIDGE AXIS ACROSS THE GULF AND NE FLORIDA INTO THE W
ATLC. THIS IS LEAVING ONLY ISOLATED SHOWERS OVER THE YUCATAN
CHANNEL AND ALONG THE N GULF COAST FROM PANAMA CITY FLORIDA TO
THE MISSISSIPPI DELTA.

CARIBBEAN SEA...
AN UPPER LOW IS IN THE NW CARIBBEAN NEAR 20N84W COVERING THE
AREA N OF HONDURAS W OF THE CAYMAN ISLANDS OVER THE YUCATAN
PENINSULA/CHANNEL AND W CUBA GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS OFF THE COAST OF NICARAGUA FROM 12N-16N W
OF 80W TO OVER CENTRAL AMERICA. UPPER HIGH COVERS THE REMAINDER
OF THE CARIBBEAN ANCHORED BETWEEN JAMAICA AND HAITI NEAR 19N76W
AND A SECOND UPPER HIGH ANCHORED N OF THE LEEWARD/VIRGIN ISLANDS
LEAVING THE CARIBBEAN E OF 80W VERY DRY TONIGHT.

ATLANTIC OCEAN...
THE BROAD UPPER RIDGE THAT CROSSES THE GULF EXTENDS A RIDGE AXIS
ACROSS NE FLORIDA INTO THE W ATLC TO NEAR TO BEYOND 32N77W. THIS
IS DRAWING DRY AIR ACROSS THE AREA AND FLORIDA AS WELL AS
DISSIPATING THE FRONT FROM THE BROAD UPPER TROUGH THAT IS
FURTHER E. THIS UPPER TROUGH IS NOW N 26N FROM 62W-74W WITH THE
ASSOCIATED COLD FRONT ENTERING THE AREA E OF BERMUDA NEAR 32N63W
S TO 29N65W WHERE IT DISSIPATES INTO THE GULF OF MEXICO ACROSS
THE FLORIDA KEYS. SMALL...WEAK UPPER LOW IS CENTERED SE OF THE
UPPER TROUGH NEAR 25N61W. UPPER HIGH ASSOCIATED WITH HURRICANE
HELENE COVERS AN AREA N OF 26N BETWEEN 51W-60W. CUT-OFF UPPER
LOW SE OF HELENE IS CENTERED NEAR 24N40W EXTENDING A TROUGH AXIS
FROM 27N35W-17N48W. UPPER HIGH ANCHORED N THE CAPE VERDE ISLANDS
NEAR 18N25W COVERS THE REMAINDER OF THE E ATLC. AT THE
SURFACE...A 1024 MB HIGH IS LOCATED N OF THE REGION WITH A RIDGE
EXTENDING S TO 20N FROM 20W-50W. THIS AREA REMAINS VERY DRY
AGAIN TONIGHT.

$$
WALLACE




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