000 AXNT20 KNHC 221043 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...SPECIAL FEATURES... HURRICANE HELENE IS CENTERED NEAR 32.9N 55.2W OR ABOUT 490 MILES EAST OF BERMUDA AT 22/0900 UTC MOVING NORTHEAST AT 13 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. SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE AREA FROM 32N-37N BETWEEN 53W-57W. DENSE OVERCAST CLOUDS WITH SHOWERS/THUNDERSTORMS COVERS A LARGER AREA FROM 31N-40N BETWEEN 51W-58W. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 38W/39W 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 WITHIN 150/200 NM OF LINE 19N30W-10N41W. TROPICAL WAVE IS ALONG 51W/52W S OF 19N WITH A 1010 MB LOW ALONG THE WAVE NEAR 13N MOVING W NEAR 10 KT. BROAD CYCLONIC ROTATION COVERS THE AREA FROM 10N-18N BETWEEN 48W-56W WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION WITHIN 75 NM OF 12N FROM 50W-54W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N13W 10N22W 12N34W 10N45W 12N53W 8N61W 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-10N E OF 30W TO JUST INLAND OVER AFRICA. ...DISCUSSION... GULF OF MEXICO... VERY LARGE UPPER LOW IS MOVING THROUGH THE N/CENTRAL PLAIN STATES WITH AN UPPER TROUGH MOVING ACROSS TEXAS INTO THE NW GULF COAST. THIS CONTINUES TO BRING DRY AIR TO THE TEXAS COAST AND INTO THE SE US. AN UPPER LOW IN THE NW CARIBBEAN EXTENDS OVER THE SE GULF S OF 27N E OF 90W. UPPER RIDGE ANCHORED ALONG THE W COAST OF MEXICO IS BEING NARROWED BY THESE UPPER TROUGHS EXTENDING A RIDGE AXIS NE ACROSS THE GULF ALONG 27N88W THEN OVER NE FLORIDA INTO THE W ATLC. THE RETURN SURFACE FLOW IS GENERATING ISOLATED SHOWERS N OF 28N TO INLAND OVER SE US BETWEEN PANAMA CITY FLORIDA AND CENTRAL LOUISIANA. CARIBBEAN SEA... AN UPPER LOW IS IN THE NW CARIBBEAN CENTERED OFF THE W TIP OF CUBA NEAR 21N85W COVERING THE AREA N OF HONDURAS W OF THE CAYMAN ISLANDS OVER THE YUCATAN PENINSULA/CHANNEL AND W CUBA GENERATING SCATTERED SHOWERS/THUNDERSTORMS OFF THE COAST OF NICARAGUA/ HONDURAS FROM 12N-18N BETWEEN 81W-85W WITH A LINE OF SIMILAR ACTIVITY EXTENDING FROM E PANAMA/COLOMBIA NEAR 8N77W NE TO 12N82W. UPPER HIGH COVERS THE REMAINDER OF THE CARIBBEAN ANCHORED OVER E CUBA NEAR 20N76W AND A SECOND UPPER HIGH ANCHORED OVER THE LEEWARD/VIRGIN ISLANDS LEAVING THE REMAINDER OF THE CARIBBEAN VERY DRY THIS MORNING. ATLANTIC OCEAN... THE UPPER RIDGE THAT CROSSES THE GULF BROADENS AS IT EXTENDS A RIDGE AXIS ACROSS NE FLORIDA INTO THE W ATLC TO TO BEYOND 32N75W. THIS IS DRAWING DRY AIR FURTHER S AND E AS WELL AS DISSIPATING THE FRONT FROM THE BROAD UPPER TROUGH THAT IS FURTHER E. THIS UPPER TROUGH IS NOW N OF 24N FROM 61W-70W WITH THE ASSOCIATED DISSIPATING FRONT/SURFACE TROUGH ENTERING THE AREA E OF BERMUDA NEAR 32N63W S TO 24N75W ACROSS THE FLORIDA KEYS INTO THE E GULF. SMALL...WEAK UPPER LOW IS CENTERED SE OF THE UPPER TROUGH NEAR 24N60W. UPPER HIGH ASSOCIATED WITH HURRICANE HELENE COVERS AN AREA N OF 24W BETWEEN 48W-57W. ILL-DEFINED UPPER LOW SE OF HELENE EXTENDS A TROUGH AXIS FROM 27N35W-19N48W. UPPER HIGH ANCHORED JUST NW OF THE CAPE VERDE ISLANDS NEAR 18N27W COVERS THE REMAINDER OF THE E ATLC. AT THE SURFACE...A 1023 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 WITH THE EXCEPTION OF HIGH CLOUDS EXTENDING N FORM THE TROPICAL WAVE ALONG 38W/39W. $$ WALLACE