000 AXNT20 KNHC 062343 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN MAY 06 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 4N20W 1N32W EQ44W 1S49W. SCATTERED MODERATE CONVECTION IS FROM 1N-5N BETWEEN 18W-22W. SIMILAR ACTIVITY IS WITHIN 120 NM OF THE AXIS W OF 40W. A POSSIBLE VERY WEAK LOW AMPLITUDE TROPICAL WAVE IS APPROACHING 30W. THIS WEAK FEATURE MAY BE ENHANCING SOME CONVECTION S OF THE EQUATOR. ...DISCUSSION... GULF OF MEXICO... ACTIVE WEATHER IS OCCURRING THIS EVENING OVER SOUTH AND CENTRAL FLORIDA. DOPPLER RADAR SHOWS NUMEROUS TSTMS QUICKLY MOVING S DOWN THE FL PENINSULA...MOSTLY FROM LAKE OKECHOBBEE SWD WHERE TORNADO WARNINGS ARE IN EFFECT. THIS ACTIVITY IS BEING PRODUCED BY UPPER ENERGY ASSOCIATED WITH A STRENGTHENING VERTICALLY STACKED LOW PRES SYSTEM OFF THE CAROLINA COAST...MORE ON THIS IN THE W ATLC SECTION. ANOTHER FACTOR IS AN ASSOCIATED BACK DOOR COLD FRONT THAT EXTENDS FROM THE W ATLC ACROSS NE FLORIDA TO THE FL PANHANDLE. A PRE-FRONTAL TROUGH LIES ABOUT 90 NM S OF THE FRONT...CLEARLY SEEN ON BOTH SATELLITE AND RADAR. THESE BOUNDARIES ARE ANTICIPATED TO PROGRESS THRU FL AND THE ERN GULF ON MON. THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF WEAK UPPER RIDGING...HOWEVER THIS RIDGE IS MUCH MORE AMPLIFIED JUST N OF THE REGION OVER THE CENTRAL U.S. A BROKEN SWATH OF MID-HIGH LEVEL CLOUDS IS PUSHING ACROSS THE W AND CENTRAL GULF BETWEEN 88W-95W. AT THE SFC...THE COMBINATION OF STRONG HIGH PRES RIDGING IN THE NORTHEAST STATES AND LOW PRES OVER MEXICO/S CENTRAL U.S. IS PRODUCING SELY WINDS TO 20 KT IN THE WRN GULF. LIGHTER E TO SE WINDS EXIST ELSEWHERE BUT STRONG NELY WINDS ARE EXPECTED TO DEVELOP IN THE E GULF LATER TONIGHT AS THE LOW PRES SYSTEM STRENGTHENS OFF THE SOUTHEAST U.S. COAST. CARIBBEAN SEA... AN UPPER LEVEL WEAKNESS OR INDUCED TROUGHING LIES ABOVE THE WRN CARIB WHILE EXTENSIVE SWLY FLOW ALOFT COVERS THE CENTRAL AND ERN ...ON THE W PERIPHERY OF A SPRAWLING UPPER HIGH CENTERED E OF THE REGION OVER THE TROPICAL ATLC. THIS UPPER PATTERN IS CONFLUENT IN THE NW CARIB PROVIDING SINKING AIR LEADING TO LITTLE ORGANIZED CLOUD COVER. WHILE THE EXTENSIVE SWLY REGIME IS HELPING TO FLARE CONVECTION ALONG THE ITCZ OVER S COSTA RICA...PANAMA AND COLOMBIA. DEBRIS CIRRUS IS BEING ADVECTED AROUND THE RIDGE ACROSS THE MAJORITY OF THE CENTRAL AND ERN CARIB. AT THE SFC...THE PRESSURE PATTERN IS FAIRLY WEAK DUE TO A TROUGH OF LOW PRES LOCATED NE OF HISPANIOLA. SHIPS AND BUOYS ARE REPORTING E TO NELY TRADES MOSTLY IN THE 10-15 KT RANGE EXCEPT STRONGER WINDS TO 20 KT ACROSS THE SRN PORTION WHERE THE PRES GRADIENT IS TYPICALLY TIGHTER. THESE LIGHT TO MODERATE WINDS SHOULD CONTINUE FOR THE NEXT DAY OR TWO AS THE SUBTROPICAL RIDGE GIVES WAY TO STRENGTHENING LOW PRES OVER THE W ATLC. WESTERN ATLANTIC... THE BIG STORY IS ASSOCIATED WITH A STRENGTHENING LOW PRES SYSTEM OFF THE CAROLINA COASTLINE....ANALYZED 1009 MB NEAR 35N74W. A BACK DOOR COLD FRONT IS PROGRESSING SWD FROM THE LOW TO NE FLORIDA. THIS LOW HAS AN IMPRESSIVE LARGE CIRCULATION WITH MULTIPLE BOUNDARIES ROTATING AROUND IT PRODUCING SCATTERED SHOWERS N OF 28N W OF 70W. THE MAIN IMPACT IS THE STRONG WINDS AS A VERY TIGHT PRES GRADIENT HAS SET UP BETWEEN THE LOW AND STRONG HIGH PRES OVER THE ERN GREAT LAKES. SHIPS/BUOYS ARE REPORTING NLY WINDS TO 40 KT NOT FAR OFF THE SE COAST. GLOBAL MODELS ARE NOW IN PRETTY GOOD AGREEMENT SHOWING THE SYSTEM STRENGTHENING FURTHER AS IT TAKES A LOOPING OR SLOW WWD MOTION TOWARD THE SE COAST. SEVERAL MODELS ARE ALSO SHOWING THE SYSTEM BECOMING LESS FRONTAL IN NATURE OVER THE NEXT COUPLE DAYS. MARINE IMPACTS ARE EXPECTED TO BE SIGNIFICANT IN THE NW PORTION OF THE AREA...REFER TO MIAHSFAT2 FOR DETAILS S OF 31N. FARTHER E...A WEAK 1011 MB LOW LOCATED NEAR 28N61W IS PRODUCING SCATTERED SHOWER ACTIVITY NE OF THE LOW FROM 26N-31N BETWEEN 55W-57W. A SFC TROUGH HANGS S/SW FROM THE LOW TOWARD THE NRN COAST OF HISPANIOLA...DEFINED BY A WIND SHIFT. CENTRAL AND EASTERN ATLANTIC... STRONG AZORES HIGH IS IN CONTROL OF THE PATTERN ACROSS THE ATLC E OF 55W. THIS HIGH IS PRODUCING A LARGE AREA OF MODERATE TO FRESH TRADES...STRONGEST E OF 25W WHERE THE PRES GRADIENT IS TIGHTENED DUE TO LOWER PRES OVER AFRICA. SCATTERED STRATOCUMULUS COVER MUCH OF THE REGION...EXCEPT S OF 18N E OF 28W WHERE THIS LOW-LEVEL CLOUD DECK IS ERODED BY SAHARAN DUST. IN THE UPPER LEVELS...A RIDGE AXIS RUNS FROM AN UPPER HIGH IN THE DEEP TROPICS TO THE AZORES ALONG 10N53W 22N45W 32N38W. THE UPPER PATTERN THEN FOLDS INTO A BROAD TROUGH ANCHORED BY AN UPPER LOW CENTERED ABOUT 300-350 NM W OF THE CANARY ISLANDS NEAR 29N23W. OVERALL...THIS UPPER PATTERN IS NOT PRODUCING MUCH MORE THAN PATCHES OF CIRRUS. $$ CANGIALOSI