TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT THU SEP 13 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...SPECIAL FEATURES... HUMBERTO MADE LANDFALL AS A CATEGORY ONE HURRICANE CROSSING THE TEXAS COAST JUST EAST OF HIGHLAND AROUND 07 UTC. AT 13/1200 UTC...THE CENTER OF HURRICANE HUMBERTO WAS LOCATED INLAND NEAR 30.3N 93.6W OR ALONG THE TEXAS/LOUISIANA BORDER MOVING TOWARD THE NE AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB. MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH HIGHER GUSTS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. HUMBERTO HAS BEEN A VERY IMPRESSIVE SYSTEM STRENGTHENING FROM A TROPICAL DEPRESSION TO A HURRICANE IN LESS THAN 24 HOURS. DOPPLER RADAR DATA DISPLAYED AN IMPROVED STRUCTURE UP UNTIL LANDFALL WITH AN EYE-LIKE FEATURE AND WELL DEFINED BANDING N OF THE CENTER. SINCE MOVING INLAND...THE RADAR PRESENTATION HAS DETERIORATED SOME...BUT THE NRN EYEWALL AND RAINBANDS REMAIN WELL DEFINED. THE STORM CROSSED VERY NEAR BEAUMONT TEXAS WHICH REPORTED A GUST TO 73 KT WHEN IN THE NRN EYEWALL. RAINFALL IS ALSO A CONCERN WITH TOTAL ACCUMULATIONS OF 5 TO 10 INCHES EXPECTED FROM SOUTHWESTERN TO NORTHEASTERN LOUISIANA...ACROSS FAR SOUTHEASTERN ARKANSAS AND INTO CENTRAL AND NORTHERN MISSISSIPPI...WITH ISOLATED MAXIMUM ACCUMULATIONS OF 15 INCHES POSSIBLE. CURRENTLY NUMEROUS MODERATE/SCATTERED STRONG CONVECTION IS WITHIN 150 NM NE AND 60 NM SW SEMICIRCLES. TROPICAL DEPRESSION EIGHT IS CENTERED NEAR 13.9N 47.5W AT 13/0900 UTC OR ABOUT 800 NM EAST OF THE LESSER ANTILLES MOVING WEST-NORTHWEST AT 9 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM SUSTAINED WIND SPEED REMAINS 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. THIS DEPRESSION HAS GENERALLY CHANGED LITTLE THROUGHOUT THE OVERNIGHT HOURS WITH THE LOW-LEVEL CENTER LOCATED TO THE N OF A PERSISTENT AREA OF MODERATE CONVECTION WHICH EXTENDS OUT ROUGHLY 120-150 NM. A BROAD BAND HAS BECOME A LITTLE BETTER ORGANIZED TO THE N AND NE OF THE SYSTEM BUT STILL REMAINS SEPARATED FROM THE CONVECTIVE MASS. SOME STRENGTHENING IS EXPECTED IN THE SHORT TERM AS THE SHEAR RELAXES SOME. HOWEVER...WEAKENING IS FORECAST TOWARD THE END OF THE PERIOD AS THE TROPICAL CYCLONE MOVES INTO A HIGHER SHEAR ENVIRONMENT. ...TROPICAL WAVES... TROPICAL WAVE HAS BEEN INTRODUCED ON THE 06Z ANALYSIS ALONG 19W/20W S OF 18N ESTIMATED TO BE MOVING W 10-15 KT. BASED ON SOUNDING DATA...THIS WAVE PASSED DAKAR SOMETIME BETWEEN 12Z AND 23Z YESTERDAY. SYNOPTIC 24-HOUR PRES TRENDS CLEARLY SHOW THE PRESCIENCE OF THIS WAVE WITH 1-3 MB PRES RISES E OF THE WAVE OVER W AFRICA AND 1 MB FALLS W OVER THE CAPE VERDE ISLANDS SINCE 06Z YESTERDAY. VISIBLE IMAGERY...LOW-LEVEL SATELLITE DRIFT WINDS AND A 07Z QSCAT PASS SHOW A FAIR AMOUNT OF CYCLONIC TURNING WITH A WEAK AREA OF LOW PRESSURE ALONG THE WAVE AXIS NEAR 10N...ANALYZED 1010 MB. SHOWERS AND TSTMS ARE WIDELY SCATTERED WITHIN 240 NM OF THE WAVE AXIS. HIGH AMPLITUDE TROPICAL WAVE IS IN THE E ATLC ALONG 38W S OF 21N MOVING W 10-15 KT. THE NRN PART OF THE WAVE IS BEGINNING TO FRACTURE BASED ON THE POLEWARD MOVEMENT OF MOISTURE SEEN ON SATELLITE AND THE UW CIMSS TPW ANIMATION. A TROUGH WAS ANALYZED TO REFLECT THIS ALONG 37W/38W FROM 22N-26N. OTHERWISE...THE OVERALL STRUCTURE HAS CHANGED LITTLE OVER THE PAST COUPLE OF DAYS WITH A LARGE SHIELD OF CYCLONIC TURNING NOTED IN THE LOW TO MID LEVEL CLOUD FIELD. DESPITE THE CONTINUED FAIR STRUCTURE...DEEP MOISTURE IS SPARSE WITH WIDELY SCATTERED MODERATE CONVECTION WITHIN 180 NM OF THE AXIS. SLIGHTLY MORE ORGANIZED ACTIVITY IS SITUATED AT THE BASE OF THE WAVE WITHIN THE ITCZ. TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 78W S OF 23N MOVING W 15 KT. A SURGE OF MOISTURE ASSOCIATED WITH THIS FEATURE IS STILL EVIDENT ON THE TPW ANIMATION FROM CIMSS...WHICH WAS THE PRIMARY TOOL USED TO TRACK THIS WAVE AS LITTLE SIGNATURE IS APPARENT IN CONVENTIONAL SATELLITE IMAGERY. THE INTERACTION WITH AN UPPER LOW CENTERED JUST S OF CENTRAL CUBA IS SUPPORTING ISOLATED SHOWERS AND TSTMS OVER CUBA AND A PORTION OF THE NW CARIB N OF 18N BETWEEN 79W-83W. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N21W 11N33W 13N39W 15N45W 10N52W 9N62W. SCATTERED MODERATE CONVECTION IS NEAR THE BASE OF AN E ATLC WAVE FROM 6N-10N BETWEEN 35W-38W AND SE OF THE DEPRESSION FROM 10N-13N BETWEEN 40W-45W. SIMILAR ACTIVITY IS WITHIN 120 NM N OF THE AXIS W OF 56W. DISCUSSION... THE GULF OF MEXICO... THE HIGHLIGHT TODAY IS HURRICANE HUMBERTO WHICH HAS NOW MOVED INLAND ACROSS SE TEXAS AND SW LOUISIANA. REFER TO THE SPECIAL FEATURE SECTION FOR DETAILS. THE REMAINDER OF THE REGION REMAINS EMBEDDED IN A MOIST ENVIRONMENT AS INDICATED BY WATER VAPOR IMAGERY AND THE CIMSS TPW ANIMATION. THE UPPER FEATURES MAINTAINING THIS WIDESPREAD HIGH LEVEL MOISTURE PLUME CONSIST OF AN ELONGATED UPPER HIGH STRETCHED ACROSS THE N GULF AND AN UPPER LOW JUST S OF CUBA. IR IMAGERY SHOWS ONLY ISOLATED SPOTS OF PRECIP. ONE SOMEWHAT PERSISTENT AREA...ALSO EVIDENT ON MOSAIC RADAR IMAGERY...IS A STREAM OF SHOWERS AND TSTMS ADVECTED FROM THE ATLC INTO THE SE GULF ROUGHLY S OF 26N E OF 85W. WEAKENING POCKETS OF SCATTERED MODERATE CONVECTION ARE OVER THE S BAY OF CAMPECHE AND OVER SRN MEXICO WHERE DIFFLUENCE ALOFT IS MORE PRONOUNCED. ISOLATED SHOWERS AND TSTMS ARE POSSIBLE JUST ABOUT ANYWHERE ELSE IN THE REGION GIVEN THE MOIST ENVIRONMENT. THE CARIBBEAN SEA... A BROAD UPPER LOW HAS BEEN DRIFTING WWD CENTERED S OF CENTRAL CUBA NEAR 21N80W. DIFFLUENCE ALOFT TO THE S OF THE UPPER LOW COUPLED WITH THE LOW-LEVEL CONVERGENCE ALONG THE ITCZ IS ENHANCING CLUSTERS OF SCATTERED MODERATE CONVECTION OVER THE W CARIBBEAN AND PORTIONS OF CENTRAL AMERICA ROUGHLY S OF 17N W OF 78W. THE INTERACTION BETWEEN A WEAK TROPICAL WAVE AND THE UPPER LOW IS PRODUCING SOME ISOLATED SHOWER ACTIVITY ACROSS THE NW CARIB AND OVER CUBA...FOR DETAILS SEE ABOVE. THE ERN CARIB IS EXPERIENCING MOSTLY FAIR WEATHER AS DRIER AIR FROM THE TROPICAL ATLC HAS BEEN ADVECTED INTO THE AREA AROUND AN UPPER HIGH. HOWEVER...THERE ARE WWD MOVING SCATTERED SHOWERS AND TSTMS WITHIN THE ITCZ THAT MAY MOVE ACROSS THE EXTREME SRN WINDWARD ISLANDS LATER TODAY. MODERATE TO STRONG TRADE WINDS ARE BLOWING ACROSS THE REGION...STRONGEST BETWEEN COLOMBIA AND HISPANIOLA WHERE QSCAT DEPICTED A SOLID AREA OF 20-25 KT WINDS. THE ATLANTIC OCEAN... TROPICAL DEPRESSION EIGHT IS THE MAIN FEATURE OF INTEREST ACROSS THE TROPICAL AND SUBTROPICAL ATLC DISCUSSION ZONE. FOR DETAILS AND REFERENCES REFER TO THE SPECIAL FEATURE SECTION ABOVE. OTHERWISE...THE ATLC BASIN IS FAIRLY QUIET THIS MORNING. THE SFC PATTERN HAS GENERALLY CHANGED LITTLE OVER THE PAST COUPLE OF DAYS. A PAIR OF 1022 MB HIGHS ARE ANALYZED ALONG AND JUST N OF OUR BORDER IN THE CENTRAL AND W ATLC NEAR 32N60W AND 36N49W. A 1028 MB HIGH IS CENTERED IN THE E ATLC NEAR 44N23W WITH RIDGING EXTENDS SW TO 28N35W. A SLIGHT WEAKNESS IN THE SUBTROPICAL RIDGING LIES BETWEEN 35W-45W ASSOCIATED WITH A TROUGH OF LOW PRES IN THE N CENTRAL ATLC. THIS WEAKNESS HAS ALLOWED WINDS TO BE FAIRLY LIGHTER IN THAT VICINITY...WITH MODERATE TRADES OBSERVED ELSEWHERE. ALOFT...A COMPLEX PATTERN IS IN PLACE ACROSS THE SW ATLC. THE CONTRIBUTING LARGE SCALE FEATURES CONSIST OF A WESTWARD MOVING UPPER LOW CENTERED JUST S OF CENTRAL CUBA...THE ERN PERIPHERY OF THE GULF RIDGE AND ANOTHER UPPER LOW CENTERED NEAR 28N64W. THE LATTER UPPER LOW ACTUALLY BECAME CUT OFF FROM THE TAIL END OF THE EXTENSIVE TROUGHING COVERING THE CENTRAL ATLC N OF OF 20N BETWEEN 32W-53W...ASSOCIATED WITH AFOREMENTIONED TROUGH OF LOW PRES IN THE N CENTRAL ATLC. THIS PATTERN IS ONLY GENERATING A SHIELD OF MID TO HIGH LEVEL CLOUDINESS AND ISOLATED SHOWERS AND TSTMS W OF 70W AND N OF 29N BETWEEN 35W-42W. MUCH OF THE REMAINDER OF THE AREA IS DOMINATED BY AN E-W RIDGE COVERING THE AREA FROM THE LESSER ANTILLES EWD WITH A MEAN AXIS ALONG 17N WITH SEVERAL EMBEDDED ANTICYCLONES. THIS RIDGE AND A CONFLUENT PATTERN...TO THE S OF A LARGE UPPER LOW NEAR SRN PORTUGAL...IS KEEPING WEATHER CONDITIONS FAIRLY TRANQUIL. CANGIALOSI