000 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