000 AXNT20 KNHC 041743 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI MAY 04 2007 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...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 6N10W 2N21W 1N35W 3N51W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF THE AXIS BETWEEN 25W-30W...34W-39W AND W OF 49W. A BROADER AREA OF SCATTERED SHOWERS AND TSTMS IS FARTHER E S OF 6N E OF 18W. THIS ACTIVITY IS ALSO INFLUENCED BY A SECONDARY SFC AXIS ANALYZED MOSTLY S OF THE EQ AND POSSIBLY A WEAK LOW AMPLITUDE TROPICAL WAVE. ...DISCUSSION... GULF OF MEXICO... THE VIGOROUS UPPER LOW THAT HAS BEEN IMPACTING CONDITIONS ACROSS THE NRN GULF OVER THAT LAST COUPLE OF DAYS IS NOW PUSHING OFF TO THE NE OVER SE MISSOURI. THE GREATEST INSTABILITY/DIFFLUENCE ALOFT IS BETWEEN THIS FEATURE AND AN UPPER HIGH OVER SRN GEORGIA. SHOWERS AND TSTMS ARE MOST NUMEROUS OVER ERN LOUISIANA AND SRN MISSISSIPPI. THERE IS SOME ACTIVITY OVER THE NRN GULF WATERS N OF 28N BETWEEN 87W-89W BUT IR IMAGERY SHOWS THE CLOUD TOPS WARMING OVER THE PAST FEW HOURS. FARTHER E...AN UPPER TROUGH EXTENDS FROM THE WRN ATLC ACROSS THE BAHAMAS AND THROUGH THE FLORIDA STRAITS. NOT MUCH ASSOCIATED WEATHER...ONLY SCATTERED CIRRUS...WITH THE GULF BEING ON THE MORE STABLE BACK SIDE OF THE TROUGH. THE SFC PATTERN IS BASICALLY UNCHANGED FROM THE PAST FEW DAYS AS THE WRN PERIPHERY OF A STRONG AZORES HIGH STRETCHES INTO THE CENTRAL GULF. WINDS ARE GENERALLY E/SE 10-20 KT...STRONGEST IN THE WRN GULF WHERE THE PRES GRADIENT TIGHTENS DUE TO LOWER PRES OVER MEXICO AND THE S CENTRAL U.S. THESE SE WINDS IN THE W GULF ARE EXPECTED TO STRENGTHEN THIS WEEKEND AS LOW PRES DEEPENS OVER THE S CENTRAL U.S. CARIBBEAN SEA... THE BIG PICTURE CONSISTS OF AN UPPER TROUGH COVERING THE WRN CARIB EXTENDING SWD FROM THE BAHAMAS TOWARD HONDURAS AND A BROAD UPPER RIDGE ESTABLISHED ACROSS THE E CARIB WITH THE AXIS ALIGNED JUST E OF THE AREA ALONG 60W. UPPER DIFFLUENCE AND EXTENSIVE SWLY FLOW ALOFT IS GENERATING AND DRAWING A LARGE SWATH OF TROPICAL MOISTURE BETWEEN THESE UPPER FEATURES ROUGHLY BETWEEN 65W-80W. WHILE A GOOD PORTION OF THIS MOISTURE SWATH IS ONLY IN THE FORM OF BROKEN TO OVERCAST MID TO HIGH LEVEL CLOUDS AND EMBEDDED ISOLATED SHOWERS...A FEW SMALL CLUSTERS OF TSTMS HAVE FIRED IN THE SW CARIB S OF 13W BETWEEN 75W-80W. AT THE SFC...THE STRONG AZORES HIGH IS PRODUCING 15-20 KT ELY TRADES ACROSS THE CENTRAL AND ERN CARIB. THESE WINDS SLACKEN SLIGHTLY IN THE NW CARIB...10-15 KT...NEAR THE SW PERIPHERY OF THE RIDGE. WESTERN ATLANTIC... A SFC TROUGH REMAINS STATIONARY IN THE WRN ATLC ANALYZED FROM THE NRN TIP OF HISPANIOLA ACROSS THE SE BAHAMAS TO 31N73W. OVER THE PAST COUPLE OF DAYS SEVERAL MODELS HAVE BEEN TRYING TO DEVELOP THIS TROUGH INTO A CLOSED LOW...BUT IT STILL APPEARS RATHER BROAD AND ILL-DEFINED. THE GREATEST CYCLONIC TURNING ON VIS IMAGES IS NEAR THE NRN PORTION OF THE TROUGH WHERE THERE COULD BE A VERY WEAK LOW LEVEL CENTER NEAR 30N74W. NEARLY ALL OF THE ASSOCIATED SHOWER ACTIVITY LIES WITHIN 420 NM E OF THE TROUGH SHEARED BY STRONG SWLY UPPER LEVEL WINDS TO THE E OF AN UPPER TROUGH AXIS WHICH RUNS FROM 32N71W ACROSS THE WRN BAHAMAS AND THE FL STRAITS. A BACK DOOR FRONT IS SLOWING SINKING SWD ALIGNED E-W ALONG 34N. A BAND OF MULTILAYERED CLOUDS AND ISOLATED SHOWERS ARE ALONG AND N OF THE FRONT. CENTRAL AND EASTERN ATLANTIC... THIS PART OF THE ATLC DISCUSSION AREA IS DOMINATED BY A 1030 MB HIGH CENTERED ABOUT 300 NM SE OF THE AZORES NEAR 34N32W. THIS HIGH IS PRODUCING MODERATE TRADES AND PATCHES OF STRATOCUMULUS CLOUDS ACROSS THE BULK OF AREA...STRONGEST E OF 30W WHERE THE PRES GRAD IS TIGHTEST DUE TO THE INTERACTION WITH LOW PRES OVER AFRICA. MODEST SAHARAN DUST IS SPREADING W ACROSS THE ATLC WATERS...E OF 28W DEPICTED BY AN EROSION OF THE STRATOCUMULUS DECK AND A HAZY LOOK ON VISIBLE SATELLITE IMAGES. IN THE UPPER LEVELS...AN UPPER LOW IS CENTERED NEAR 28N37W WITH A SWLY JET BRANCH ON ITS S SIDE TRANSPORTING HIGH LEVEL MOISTURE FROM 20N-30N BETWEEN 25W-40W. THIS LOW IS EMBEDDED IN A STRONG RIDGE NEARLY STACKED ABOVE THE SFC HIGH OVER THE AZORES. THE COMBINATION OF THE SFC AND UPPER RIDGING IS PROVIDING THE WIDESPREAD TRANQUIL CONDITIONS. THE EXCEPTION IS THE UPPER SLY FLOW S OF 15N E OF 35W...ON THE W SIDE OF AN UPPER RIDGE OVER AFRICA...WHICH IS FAVORING CONVECTION IN THE ITCZ. $$ CANGIALOSI